# What is Gain?



## superleadfixer

You know, too often I see lots of guys that have the misconception that gain=volume, when this is simply not the case. You will spot these guys as they tend to set the volume of each channel with the gain pots instead of the channel faders. 

Gain in a live PA is signal strength. A microphone converts sound pressure into electrical signals that correspond with the frequencies/sounds picked up by the microphone element. These signals are sent through a mic cable into the mixer board. However, these signals are so weak in amplitude(again signal strength) that they need some sort of gain to increase the amplitude of the signal so that it can drive the gear down the signal chain. If the signal flow down the signal chain is not strong enough, the gear it runs through will be less effective and it will not be able to process the signal to its full capacity. This is because the weaker the gain in the signal, the less musical content it will contain for the gear to process. 

With gain also comes higher signal to noise ratio. Signal to noise ratio(commonly referred to as S/N Ratio) is the ratio between signal content and noise content. All gear produces a small amount of "noise", which is the common "hiss" noise you hear in systems with no signal going through. The better the gear, the lower the amount of produced noise in the system. A signal to noise ratio of 1:1(1 part signal to 1 part noise) would mean that the level of signal and the level of noise are at an equal, which is definitely not desirable as it will "cloud up" the signal. However, the more you turn up the gain, the stronger the signal becomes and the higher the S/N ratio. A 90dB-100dB or higher S/N ratio(90dB-100dB of signal to 1dB of noise) is a much more desirable S/N ratio for optimum performance and superb clarity. 

Also, with more gain comes more voltage "swing", or dynamic range. This is where the gain structure comes into play. On a mixer board, you'll see that all the faders are labeled in negative dBs, until you get about 3/4 of the way up on the fader travel, which will be a 0dB or a "U" mark. Mackie's tend to use the "U" mark, which stands for Unity Gain. In the law of Unity Gain, this law states that the only place in the signal path that the signal should receive ANY kind of gain is from the "Gain" or "Trim" control on the channel. If you push the fader past the 0 or U mark, the signal will then be receiving gain from the fader itself, which can overdrive/clip the main mix buss inside the board. On all mixers, with the channel faders set at the 0 or U mark, and with the Main Mix fader at the 0 or U mark, and with no boost from the channel EQ, whatever signal level is coming from the Gain or Trim control is what will be seen at the mixer's output and at all various points in the mixer signal flow path. With maximum possible gain coming from the trim control itself, this will feed each channel EQ with maximum signal, making the channel EQs MUCH more effective to where you won't need to boost at all from the channel EQ. 

As a matter of fact, when I run sound, I take whichever bands I want to stand out more and leave them completely flat, then cut everything else around it. With max gain coming from the Gain or Trim control, your EQ cuts become MUCH more effective. For instance, on drum channels I typically leave the lows and highs flat. I then put in about 3-6dB of mid cut(depending on the drum), and as I'm listening to the drum I'm EQing, I sweep the frequency control until that drum sounds nice and punchy with plenty of attack definition and clarity(usually around 200-400Hz...each drum is different). With only EQ cut put into the EQ, I can now punch some more gain from the Gain or Trim control through the channel, allowing for an even more powerful signal. 

Most gear down the line from the mixer will feature input and output controls. Most of these controls have a 0 or U setting. Set these at 0 or U and that same signal coming from the mixer will flow through each piece of gear from input to output while maintaining the same signal level it had coming from the Gain or Trim stage in the mixer. 

The crossover, however, is a little different. The low band, since it typically only passes through frequencies from 40Hz to 100Hz, will have less signal energy than the high band as the high band is passing through a lot more frequencies than the low band, so you may need to punch up the low gain on the crossover so that the low band will clip at exactly the same time as the high band. On my crossover, the input and high bands are at 0dB and they both clip at the same time, but the low band required about 5dB of gain in order to clip at the same time with the high band and the input. 

Next comes the setting of the amp's input attenuators. Another common misconception of these controls is that they somehow control the OUTPUT of the amp and if you don't max them out then you won't get the full power output from the amps. This is not the case at all. These controls simply control the input sensitivity of the amp. The input sensitivity rating specifies how much voltage is required at the input of the amp to get the output to swing to full clean power before clip. Most amps are rated anywhere from 1VRMS to 2VRMS with the attenuators maxed out. Well, most +4dBu mixers with the gains maxed out and all faders at unity usually put out around 9-10VRMS of signal. With the amp's input attenuators maxed out, you're gonna hit clip long before the mixer puts out its full rated output. Once the amp hits clip, you can't go anymore...PERIOD! So in effect you actually end up sacrificing a good 8 7-8 volts of signal strength from your mixer, which results in about an 18dB-20dB loss in dynamic range/headroom, which amounts to much less voltage swing from the amps. This is where the amp's input attenuators come in. By turning them down to the point where the amp will clip at exactly the same time as the mixer/house graphic/crossover, you can now get the full 9.8 volts of signal from your mixer down the signal chain and into the amps, resulting in max dynamic range/headroom and a much larger voltage swing from the amps, which results in a much more powerful, cleaner sounding system with lots of punch and clarity. By dialing down the input attenuators, the amps will STILL put out full power...it will just take a much larger signal to get it to put out full rated power, which is what you want. A big high gain signal results in a signal with much more musical content for the gear to work with, making each piece of gear MUCH more effective, allowing you to get the most performance out of your gear. 

Another one I see a lot of is guys that max their trims out, but then set the main mix fader at unity and control the overall mix volume with the channel faders. Again, you're limiting your system this way plus making it harder on yourself to control an overall mix volume. Typically what I do is I subgroup vocals to groupd 1/2 (1-Left 2-Right) while subgrouping drums to groups 3/4(3-Left 4-Right). I then set all vocal faders plus the vocal subgroup to the 0 or U mark while maxing out the gain on all vocal channels, which will give me max level from the vocals. This way if the vocals are getting drowned out, I know to pull the instrument channel faders down to better balance with the vocals. All drum channels I set to the 0 or U mark with max Gain/Trim, except the snare and overhead, which will almost always be too loud with the fader up that high, so I start with the snare and overhead faders halfway between full down and the 0 or U mark. I then set the overall volume of the drum mix with groups 3/4, which almost always end up about -5 to -6dB below the vocal subgroups. I then set the guitar and bass faders about halfway up. With max level coming from all channels, I can now control the overall mix volume with just one fader, the Main Mix fader, while maintaining the same balance as the volume changes throughout the night. This fader setup technique always starts me out pretty close to a good mix. Then as the band kicks off the night I fine tune the balance/overall volume, slight EQing of the vocals(almost always Low/Low Mid cut is needed for the vocals to cut through, then dial in the effects last. Usually I have the band dialed in by the end of the first song one shot go. 

To Summarize: 

Gain does not equal volume 

The amp's input attenuators DO NOT control the amp's output level 

Always max out all gain controls for the most clean and clear signal from the source 

Set the loudest instruments in the mix's faders to 0 or U on the channel faders, then use the remaining faders to balance the rest of the instruments to those instruments 

Control your overall mix volume with the Main Mix fader, not the channel faders


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## Guv'nor

Great as usual!!!

8)


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## superleadfixer

In a different view/more "tube amp" oriented simplified version, here are some basic info on gain, etc... As you will see gain and distortion ain't the same thing but works togheter.....

*Overdrive*: Used to be called Distortion but that isn't descriptive enough. It is the idea of using one small amplifier (preamp) to push another one very hard, causing it to overdrive and distort. When done properly, it is controllable to the limit... 

*Saturation*: A condition in which maximum current is reached and no more current can possibly flow. 

*Distortion*: The difference between what goes into an electronic device and what comes out. 

*Clipping*: A tube can be made to draw more current or less current. If it draws too so current, that no matter how positive the grid goes, the tube cannot pass any more current, then the tube is saturating and the top of the wave is "clipped" off. Instead of being round, it is flat. This is called clipping. It can also happen if the tube draws too little current because if you keep drawing less and less, you will eventually get to the point of no current. This condition is called cutoff. If you reach cutoff during a portion of a signal, then the bottom of the wave is "clipped" off and clipping is said to have occurred. 

*Linear/non linear range*: The tube's response is the most linear when it is operating exactly half way between saturation and cutoff. When it operates close to the limits of cutoff or saturation, it is operating in the most non-linear portion of the tubes operating curve. 

*Gain*: The amount of voltage amplification in the preamp section of an amp. This voltage amplification ultimately drives the power tubes which do not add any more gain. The power tubes add current (power).


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## superleadfixer

.....to concluse on what is GAIN.........

*SETTING PROPER GAIN STRUCTURE:* 


One of the most overlooked yet most important things in a typical band's PA system is gain structure. Gain structure is the practice of matching the levels throughout your system so that: 

1) Each device in the chain clips at exactly the same time 

2) The only place the signal receives ANY kind of gain is at the trim(channel input gain) control 

3) The signal level stays exactly the same as it is coming out of the trim control all the way to the power amps 

In other words, if you have a +22dBu signal coming out of the trim control, a +22dBu signal will be seen at the amp's inputs. The ONLY place the signal should receive ANY kind of gain is from the trim control. 

Again, another example...a +22dBu signal comes off the trim control. It should maintain this value through the channel EQ, the channel fader, subgroup fader, main mix fader, house EQ, crossover, and right to the amps. When the gain stays the same throughout the whole system, this is known as a "unity gain" system. 

On each fader on most mixers, there will be a "0" or a "U" mark(most Mackie boards use the "U"). Setting the channel, subgroup and master faders to this mark will ensure unity gain through the mixer. In other words, with the fader set to the unity gain mark, whatever is coming from the trim control will appear at the outputs of the mixer. 

On all PA gear, you have gear that is either +4dBu or -10dBv compatible. Some pieces of gear have a switch where you can switch it to either +4 or -10. This matches the inputs and outputs to the type of mixer you have. Most "consumer" gear is -10dBv while "pro" gear is +4dBu. In this tutorial we will be working with +4dBu gear. 

Most +4dBu gear has an input and output rating of +22dBu. 0dBu=0.775 Volts, so +22dBu is roughly about 9.756 Volts. Mackie mixers actually have a +28dBu output rating, however that's just to give you another +6dBu of headroom to keep from clipping the mixer's output stages. The max output from each channel's trim control is actually +22dBu. 

Power amplifiers, however, have an input sensitivity rating that is much lower than that. The input sensitivity rating on power amps is the minimum voltage required on the input to cause the amp's output to put out full clean power. Most power amps have an input sensitivity rating of about +3dBu-+8dBu. This is why power amplifiers typically have input attenuator controls on them, which are the volume knobs on the front panel. A VERY common misconception is that if you don't set the input attenuators all the way up that you won't get full output from your amps. However, power amps are fixed gain devices...they will put out full power no matter where the input attenuators are set, however, depending on where they're set, it will just take a much larger signal to push the amp to full power. Judging by this statement, we now know that all the input attenuators do is raise and lower the amp's input sensitivity. The input sens rating that is advertised in the power amp's user manual is the sensitivity of the amp's input with the attenuators fully clockwise(all the way up). This is why they're there. I mean, for example, let's say that your mixer is capable of putting out +22dBu of signal, yet your most sensitive amp clips at +4dBu at it's input with the attenuators fully up. Well, now you're sacrificing +18dBu of gain/headroom you could be getting out of your mixer because once your amp is at it's clip point...that's all you get. This is why the input attenuators are there...so that you can match your amp's input sensitivity to your mixer/crossover. 

The reason proper gain structure is important is so that we get max gain from the mixer, giving us more dynamic range(headroom) and a lower noise floor. Max gain from the mixer will increase your signal to noise ratio, giving you better seperation between instruments. It also makes your channel EQs MUCH more effective. I see a LOT of people use WAY too much boost from the EQ itself than from the gain control. If you flatten the EQ, then maximize the gain from the trim control, your EQ will be MUCH more effective to where on some instruments you may have to use cut more than boost, which enables you to get even more gain from the channel's trim control. Too much boost from the EQ rather than from the trim will cause phase distortion, which will cloud up, or muddy up your signal to where it almost sounds buried in the mix. 

Following is a step-by-step procedure for setting proper gain structure. You will need a test CD with a pink noise track to do this. Pink noise is every frequency within the human hearing range played simultaneously(at the same time). You can download a full blown test CD featuring all kinds of test signals, including pink noise, frequency sweeps, left/right test(to make sure you wired the system so that left is left and right is right). 

Test CD Download 

Test CD Info/Track List Download 

For this procedure, set all channel EQs flat, all channel Low Cut filters off and all faders all the way down: 

1) Play the pink noise track through two channels. Pan one channel hard left and the other hard right. 

2) Rotate the left channel's trim control clockwise until you see the channel's "Clip" or "Overload" indicator start to come on, then back off until the indicator JUST turns off. You are now at the max gain setting on the trim. 

3) Repeat step 2 for the right channel. 

4) Set both the left and the right channel's faders to the "0" or "U" mark. This puts the channel at unity gain and sends the full signal from the trim control to the main mix buss. 

5) Make sure both the left and right channel's are assigned straight to the main mix buss. 

6) Set the main mix fader at the "0" or "U" mark. Now the trim control's full signal will appear at the mixer's outputs. Run this signal through your crossover. Set your crossover's input and output controls to the point where the input/output clip indicators JUST start to come on, then back off until they JUST go out. If your crossover's max input rating is +22dBu(it should be), then it like the mixer should be JUST going into clip. 

7) With the speakers disconnected and the amp's input attenuators fully counterclockwise, turn your mains/subs amps on. 

Rotate each input attenuator clockwise until the amp's clip lights are JUST starting to come on. 

*Note: Most amps that are bridged will only use Channel 1's input attenuator and Channel 2's will not be active. 

9) Turn on your crossover's built in limiter and set the threshold to it's highest point. Then slowly lower the threshold to the point at which the amp's clip indicators JUST go out. 

Your gain structure is now properly set, and your limiter will protect your amps from going into clip. 

10) Turn off your amps and reconnect the speakers, then turn them back on. 

11) Now play a music CD of your choice through the system, and listen. Almost always I find that when the mains amp is set to clip at exactly the same time as the subs amp, the mains are almost always too loud, so you'll have to turn the mains amp input attenuators down more to balance the mains to the subs. This will give you even more headroom on the mains amp. 



Now when you sound check your signal sources (i.e. instruments)...have each performer play the loudest that they'll play during the performance. Making sure each channel's EQ is flat at this point, rotate the trim on each instrument channel until the clip light JUST starts to come on, then back off a hair. GET AS MUCH GAIN AS YOU POSSIBLY CAN FROM THE TRIM CONTROL!!! THIS IS VERY IMPORTANT!!! Bring the channel's fader up to 0 or U, then slowly bring the master fader up to performance volume. Listen to the instrument and apply EQ if necessary, then reset your trim as stated above. Do this for all instruments. 

Set all channel/subgroup faders to the 0 or U mark, then slowly bring the main mix up to performance levels. Listen to the overall mix, if you need more of a certain instrument, bring the other instruments down around it. It's always helpful to subgroup drums and vocals since they take up more channels than guitars usually(especially drums). ALWAYS keep the lead vocal channel and the vocal subgroup faders at 0 or U to get the max signal from your vocal mix. Balance your backup vocalists to the lead vocalist. The drum subgroup faders will typically be about 5-10dB lower than vocals, depending on personal taste. Then bring the guitar and the bass channel faders up to balance with the drums and vocals. 

Basically the key is to start with all channel/subgroup faders at 0 or U, then listen to the live mix, and bring down the faders on channels with instruments that stand out too much. Drums and lead vocal channels, with the exception of snare, hi hat and overhead channels will almost always stay at 0 or U, then balance snare, hi hat and overheads to the kit. Then slowly bring the guitars and bass into the mix until they blend with the drums and vocals well. You may have to EQ them slightly to make this happen. 

I hope you guys find the above information useful.


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## HOT TUBES 70

wow !! smart bunch of guys i'd say !!!!!!
thanks guys for the great info !!!!


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## cistec

WELL DONE! NOW all we need is is a full picture step by step youtube video to really finish it off..come guys! you have come this far..lets set the standard and watch the others weep..just let me know when you do one!

cistec


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## thelorddread

what an awesome thread.


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## rockinr0ll

Very interesting. I will use this as a guide with my next attempt at tonal nirvana. Thanks.


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## Russelll

Very good, I think I'm going to like this place. . The simple answer to "What is gain?" could be, simply put, "the ratio between input and output. A gain of 1, also known as unity gain, is when input voltage is equal to output voltage. A gain of 2 is a 1:2 ratio, and so on.


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## airborne strat

Superleadfixer,
You have in a few posts made what all my college professors(yes in Audio Engineering) took semesters to teach. BRAVO!!


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## rockinr0ll

What is EQ?

[ame=http://www.youtube.com/watch?v=TQanVdQPAMg]YouTube - Guitar Lesson - EQ Settings On Your Amp[/ame]

That guy is are right on the money. I wish I would have watched it a long time ago.


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## richieG

rockinr0ll said:


> What is EQ?
> 
> YouTube - Guitar Lesson - EQ Settings On Your Amp
> 
> That guy is are right on the money. I wish I would have watched it a long time ago.



I watched this and the point he makes at the end is so true... go an play live in a band and it all changes.

I kinda laugh at non gigging guys who want to sound like slash or SRV or whoever. What is often overlooked is that the band defines your tone to a great degree. Imagine if you could pull your favorite guitarists, guitar track out of the mix...chances are it is going to sound ordinary on its own, but in the band context it sounds awesome.


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## Wilder Amplification

airborne strat said:


> Superleadfixer,
> You have in a few posts made what all my college professors(yes in Audio Engineering) took semesters to teach. BRAVO!!



Wow...superb job! Too bad they're not his posts (copy/paste works wonders). These are copy/paste jobs from MetroAmp where I was the original author of these threads 4 years ago.

http://forum.metroamp.com/viewtopic.php?f=17&t=3800&start=0&st=0&sk=t&sd=a

http://forum.metroamp.com/viewtopic.php?f=17&t=3635&start=0&st=0&sk=t&sd=a


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## MajorNut1967

Wilder Amplification said:


> Wow...superb job! Too bad they're not his posts (copy/paste works wonders). These are copy/paste jobs from MetroAmp where I was the original author of these threads 4 years ago.
> 
> Someone got caught!


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## thrawn86

Nothing's safe!!! Wow, that's lame Jon. Amazing that he wouldn't even caption them as yours. :eek2:


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## thrawn86

If anyone is wondering why I keep puting a 'period' in all these old posts, it's because of spammers. When the mod's delete them, for some reason they stay on my 'new posts' tab and clutter up everything. Sorry gents!


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## Reginald

Transistor Preamplifier Calculator


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## robertlatham1

hey just a quick add guys

try turning your gain down and your master up in a in-band mix this helps get into power tube overdrive which gives a much more musical type overdrive/distortion. to my ears preamp overdrive/distortion is not as rich or full and contains less harmonics and has less head room.

I use a JMP 2203 with Master volume. (2 power tubes pulled out most of the time)
high input with the gain set to just barley overdriving/distorting then use the master volume to take me into judas priest/iron maiden rythem overdrive territory. then for lead boost i use a ts808 with a JRC 4558 opamp (old a-- ibenez overdrive pedal) set for more of a clean boost which pushes the preamp of the 2203 a tad bit harder causeing the power stage to go into full on overdrive/distortion. if i want cleans, there is a volume knob and tone knob on my guitar for a reason. works real well!


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## Reginald

Reginald said:


> Transistor Preamplifier Calculator



IT'S IMPOSSIBLE!!
I've not wrote this reply above(labelled as of mine),which is wrote 'transistor Preamplifier Calculator' in,with my avatar and my profile....
Who's used avatar and profile of mine,passing he off as myself? an able hacker man?


However,very great topic,very great explaination about 'gain' ,thanx a lot buddies to u all.


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## MM54

As is the tendency with this forum software, someone's post got deleted and now it shows that there is a new post, which I cannot view to clear the notification. This is, therefore, a post to override that which was deleted, enabling me to clear out the 'unread topic' status and return the little power switch on the forum main page back to it's off (no new posts) state.

Thank you for your time.


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## Reginald

ok,thanx ,I understood...
hey,look....about sustain....someone could explain also the difference about sustain and gain....
there are many people who think about if u increase the gain,u will obtain even more sustain...or better ...the notes doesn't die under your fingers( I don't know how in English,sorry).actually those guys ,I tthink, need and search only more sustain not more gain...but they think is matter of gain....actually,is matter about sustain,I think
...considering JCM800 for example...it owns much gain,but little sustain...it too 'dry' sustain,'dry' sound.


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## rockback

Most gear down the line from the mixer will feature input and output controls. Most of these controls have a 0 or U setting. Set these at 0 or U and that same signal coming from the mixer will flow through each piece of gear from input to output while maintaining the same signal level it had coming from the Gain or Trim stage in the mixer.


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## diesect20022000

airborne strat said:


> Superleadfixer,
> You have in a few posts made what all my college professors(yes in Audio Engineering) took semesters to teach. BRAVO!!



thats because they're paid for one and because they're approach is for a generalized/average learning curve. I agree though.


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## diesect20022000

robertlatham1 said:


> hey just a quick add guys
> 
> try turning your gain down and your master up in a in-band mix this helps get into power tube overdrive which gives a much more musical type overdrive/distortion. to my ears preamp overdrive/distortion is not as rich or full and contains less harmonics and has less head room.
> 
> I use a JMP 2203 with Master volume. (2 power tubes pulled out most of the time)
> high input with the gain set to just barley overdriving/distorting then use the master volume to take me into judas priest/iron maiden rythem overdrive territory. then for lead boost i use a ts808 with a JRC 4558 opamp (old a-- ibenez overdrive pedal) set for more of a clean boost which pushes the preamp of the 2203 a tad bit harder causeing the power stage to go into full on overdrive/distortion. if i want cleans, there is a volume knob and tone knob on my guitar for a reason. works real well!



when you drive the power tubes you're eliminating headroom so that confused me. I may be missinterpreting that. Also, it's not a good idea to pull (presumably the outside pair) of power tubes to drop your output. You can seriously damage your amp. Specificaly the trannies. It works but, at a penalizing cost. I'd hate for you to blow up an amp like that and ALOT of people do. You'd be better off getting a quality attenuator though you would want to get speakers that drive at lower volumes but, with the same characteristics as your current ones to get closer to the same sound.


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## diesect20022000

peavey 5150/6505,Windsor and more .......preamp gain and post amp gain. interestingly enough the pre and post are preamp volume and power amp volume effectively "distortion and volume".Someone needs to let Hartley know that he's mislabeling his amplifiers.


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## Adrian R

diesect20022000 said:


> peavey 5150/6505,Windsor and more .......preamp gain and post amp gain. interestingly enough the pre and post are preamp volume and power amp volume effectively "distortion and volume".Someone needs to let Hartley know that he's mislabeling his amplifiers.




Dude..that Avatar???????


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## frethand101

Wow, damn good thread, I even broke out a notebook & was scratchin' down sum notes here & there..

Now this is what I'm talkin' about!!..


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## fastdave

Very interesting Jon, I was noticing quite a lot of typo's and wondering if he hadn't proof read it, thinking that 95% of amp enthusiasts wouldn't understand anyway - I come on to the rest of the posts and discover to my delight that there are people who got it, and to my dismay, this chap hadn't even given you an acknowledgement.
How dissappointing people are sometimes.
Not you sir, I fully appreciated your advice on biasing the other day - I even had some close tolerance 1 ohm resistors at hand.
Many thanks - death to all plagiarists.
Dave.


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## Lane Sparber

What is Plagiarism? Some asked me so here we go.!!

-Lane


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## jazzy cian

Wilder Amplification said:


> Wow...superb job! Too bad they're not his posts (copy/paste works wonders). These are copy/paste jobs from MetroAmp where I was the original author of these threads 4 years ago.
> 
> MetroAmp.com Forum &bull; View topic - Gain Explained
> 
> MetroAmp.com Forum &bull; View topic - Setting Proper Gain Structure



Ha ha ha, Love it!!!! Bad form for not crediting the original source!!!


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## Sir Crunch A Lot

Wilder Amplification said:


> Wow...superb job! Too bad they're not his posts (copy/paste works wonders). These are copy/paste jobs from MetroAmp where I was the original author of these threads 4 years ago.
> 
> MetroAmp.com Forum &bull; View topic - Gain Explained
> 
> MetroAmp.com Forum &bull; View topic - Setting Proper Gain Structure



Ha ha. This is great.


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## Maçon

How do you create a new group? not a relevant but also quick and can't usually get customer service... So can you tell me how possibly to create a group anyone? I appreciate it -I can't seem to find this link/button!


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## dirtyhippie08

*!!*

Great thread! Answered a ton of questions i've had. Thanx!


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## Heritage Softail

Cool thread. Seems the cut and paste guy cut and ran. No prob with posting some wisdom from another source, the lack of acknowledgement is unethical. 

But on gain. 

Whatever sounds best to the song. Some like more and some less. I like power tube distortion in new country and bluesy stuff. In modern metal or rock it is the curse of of tight riffs. 

Dialing up enough gain to sound right, and proper tubes in the power section to have dynamic punch in the riffs works for my ears. Over compressed over the top gain just isn't it for me. 

Enough gain, less bass, punchy power section = The Shit!


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## ---

Reginald said:


> ok,thanx ,I understood...
> hey,look....about sustain....someone could explain also the difference about sustain and gain....
> there are many people who think about if u increase the gain,u will obtain even more sustain...or better ...the notes doesn't die under your fingers( I don't know how in English,sorry).actually those guys ,I tthink, need and search only more sustain not more gain...but they think is matter of gain....actually,is matter about sustain,I think
> ...considering JCM800 for example...it owns much gain,but little sustain...it too 'dry' sustain,'dry' sound.




You need to look into compression for sustain. Find yourself a nice compressor pedal. it'll do the job. Cheers - Trev


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## sepulchre

Trev-K6ESE said:


> You need to look into compression for sustain. Find yourself a nice compressor pedal. it'll do the job. Cheers - Trev



Good point, Trev. Nailed it. 

I personally don't see any problem with the sustain of the JCM800 2203 design. Maybe it's the guitar being used? Anyway, if sustain is the problem, the right compressor is the answer.


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## Wycked Lester




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## Marshall_Watts87

I love Gain and is why the JMP-1 is such a beautiful sounding versatile device. First off you get 2 OD's voiced differently. and the with the power amp you can select a voice switch to make it less or more aggressive. I got hard rock sounds on OD 1 with the gain at 8, that's how badass it is. then put it on 10, still sounds cool and the sweet spot is 12-16 on both OD's in my opinion. But definitely sounds amazing from 16-20, especially if you don't scoop the mids, that doesn't mean put a lot of mids, just a touch! this unit is amazing, I've got like 20 different patches of gain structures, from Eddie Van Halen, Randy Rhoads, JAKE E LEE, to James Hetfield, and Stephen Carpenter. unbelievable.


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## Ed Hunter

I always understood "GAIN" as the volume of something and "distortion" and 'break up" as what you hear when the pre amp is pushed or the signal itself overdriving ?


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## jbale

I received an Ashdown 100 watt as a present years ago before they stopped building guitar amps, I was not really interested in playing with distortion at all, yea I'm an older rocker I still call crunch distortion at times, I played a lot of clean tunes; I've been a drummer for ever but also played guitar some, I kept getting too much crunch and not enough clean tones, so I played with the tone controls and found I had to turn the master to a 1/4 then the volume to 4, 5, or 6 for real clean and crunch was master on half or more and volume about the same, the crunch was about the best I'd heard besides a Marshalls. Sorry I don't remember what the amp was other than Ashdown, it was stolen, the head was at an out side gig, another guitarist was using it and I was packing my drums up, never got it back and I stopped trusting many but that was 30 years ago. Great info on this thread but often way too wordy for me, specifics would be nicer.


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## USAPatriot

Here's an interesting question. At least to me.
I have an MXR-108 EQ that I run in the loop of my DSL40C. On one side of the pedal is a slider that says volume. On the other side there's one that says gain. I don't see how the two can be different. What's up with that? -Rod-


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## mickeydg5

A volume control can be used to describe various types of signal level adjustment.
A gain control is a type of volume control in that it controls the signal level more or less at the input prior to gain blocks. Lower levels will produce less gain which equates to a lower level signal at the output.

The M-108 from what I can tell has gain modules for input, each EQ band and output. So raising the dB of the input will increase overall gain of the unit, which may result in more distortion, whereas the volume slider will only affect what is being output post input and EQ gain blocks.


----------



## USAPatriot

That makes at least some sense to me. Could I assume that with the MXR's gain on max, the amount of gain would equal the amount of gain on the amp alone? Volume is basically dry signal pass-thru? -Rod-


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## mtm105




----------



## Leigh

GAIN-noun- the amount of voltage amplification in the preamp section of an amplifier. This voltage amplification ultimately drives the power tubes which do not add any more gain. The power tubes add current ( power)


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## BanditPanda

Leigh...that has just confused me ! ( not hard to do ) I thought gain was a term used to describe the over driven or distorted sound which happens when pre amp or power tubes are over driven.
Most prefer the sound of power amp over drive to pre amp tube over drive.
When you say ..."power tubes which do not add any more gain "....when power tubes are over driven do they not produce gain i.e. O/D tones ?
BP


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## Matt_Krush

Gain (voltage) = Voltage out/Voltage in

Distortion/overdrive isn't always an effect of high gain. You can design circuits to go into saturation/cutoff without much 'gain'


----------



## pleximaster




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## Im247frogs

pleximaster said:


> View attachment 49863


Probably the only truly effing funny version of this meme on the entire internets.


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## fifteenohms

Reginald said:


> hey,look....about sustain....someone could explain also the difference about sustain and gain....



Gain is like this: you bump into your chick’s hotter girlfriend, and she remembers you.

Gain with sustain works like this: she informs your gal to give you her number, and she does.

Sustain then is: getting a table for 3 from now on.


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## mickeydg5

fifteenohms said:


> Gain is like this: you bump into your chick’s hotter girlfriend, and she remembers you.
> 
> Gain with sustain works like this: she informs your gal to give you her number, and she does.
> 
> Sustain then is: getting a table for 3 from now on.


----------



## john hammond

gain is signal strength.
increasing gain is increasing sparkle,dirt distortion, mud.
increasing volume makes the amp louder.
you can have high gain and low volume, if your amp has some sort of master volume capability
turn up the channel volume on an old marshall jmp, and you turn the volume and gain up at the same time.
put a ppimv on it, and the channel volume becomes a gain knob, and the master volume becomes the volume.
if you have a pedal with ' gain' and ' volume, or level'...2 sliders or knobs, then that's the same thing, one is gain, and the other a master volume.


----------



## spacerocker

GAIN = in the "normal" world = Amplification

You have circuit with a 10mV peak-to-peak signal on the input, and 100mV on the output, you can say that the circuit has a gain of 10 (or 3dB).

Now, the GAIN control on the Pre-amp of a Guitar amplifier DOES NOT alter the GAIN of the circuit. Equally, the Master Volume on the amp DOES NOT increase the gain of the Power amp!


What both these controls do is alter the level of the signal going into those parts of the amp (Pre-amp "GAIN" control alters the signal level going into the pre-amp, MV control alters the signal level going into the Power Amp) The gain of both those parts of the amp is fixed by the circuit design.

The confusion occurs because Guitarists almost always use the term "GAIN" to mean "signal clipping", "overdrive", "Dirt" or "Distortion"

With the "Gain" set low, the signal going into the pre-amp is small, and if the GAIN is low enough, the resulting sound may be clean and un-distorted. But because guitar amps are designed (on the whole) to distort, or clip, as the input signal is increased (by turning up the GAIN control) - the resulting output signal amplitude would be higher than the pre-amp power supply can contain. The result is that the top of the signal is clipped off - clipping occurs! This gives us the overdrive we want, the higher the input signal (from the GAIN pot) the higher the output tries to be, and the more "clipped" or over-driven the sound is!

The same happens with the power amp if the amp is a Master Volume model, then the input to the power amp from the pre-amp goes though the Master Volume pot. This sort of "scales-down" the (possibly over-driven) output from the pre-amp, and sends it into the power section. It is still over-driven, but the MV allows it to be louder or quieter. If the amp is quite powerful, no further overdrive or clipping may occur, but if the MV Pre-amp Gain is high enough, and the MV setting is also high, the signal into the power amp may be large enough to cause clipping in the power section. This adds more overdrive to the sound and us usually considered desirable. However with high power amps, this may not happen until the amp is VERY loud! at lower volumes, most of the clipping and overdrive comes from the pre-amp!

So the GAIN control does NOT alter the gain of the amp. But it does affect the level of clipping or overdrive in the pre-amp! If we think of GAIN = Overdrive it all makes sense! It's another case of technical terms being mis-used in the guitar world - e.g. "Vibrato arm" on a Fender is (mis) called a "Tremelo"!

Here's another one for you - the accelerator on a car is NOT a speed control - it is a "Torque demand control" !


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## mickeydg5

Just to throw this in, the very definition of gain here is the actual "gain" in signal level from one point to another.
The potentiometer or other signal/volume control device whether called GAIN, PREAMP VOLUME, VOLUME, MASTER VOLUME, PPIMV, VVR, EPA, POWER SCALING or something else still controls the "gain" of the amplifier.

Anything that controls the signal level is a gain control.


----------



## spacerocker

mickeydg5 said:


> Just to throw this in, the very definition of gain here is the actual "gain" in signal level from one point to another.
> The potentiometer or other signal/volume control device whether called GAIN, PREAMP VOLUME, VOLUME, MASTER VOLUME, PPIMV, VVR, EPA, POWER SCALING or something else still controls the "gain" of the amplifier.
> 
> Anything that controls the signal level is a gain control.



I see what you are saying - but in electronic terms, GAIN does not equal "an increase from one point to another". it means the multiplication factor of a circuit.

Suppose we have a circuit where for an input signal of 1V Peak-to-Peak, the output is 2V Peak to Peak. That circuit would have a gain of 2.

Now suppose we increase the input to 2V. The output will have gone up to 4V. Does that mean we have increased the gain? NO - because the gain which equals output voltage divided by input is still 2.

If we have a so-called "GAIN" pot on the input of the circuit I described above which can be turned up or down to control the signal level going in, then that pot is NOT strictly a GAIN control, as the GAIN of the circuit stays the same, irrespective of the level of the input!

A true GAIN control would increase the output of the circuit even if the input stayed the same

So I disagree with this statement "The potentiometer or other signal/volume control device whether called GAIN, PREAMP VOLUME, VOLUME, MASTER VOLUME, PPIMV, VVR, EPA, POWER SCALING or something else still controls the "gain" of the amplifier." - even though this is a common mis-conception!


----------



## mickeydg5

USAPatriot said:


> That makes at least some sense to me. Could I assume that with the MXR's gain on max, the amount of gain would equal the amount of gain on the amp alone? Volume is basically dry signal pass-thru? -Rod-


No. Every device has its own design, input levels and output levels. You can control the gain of the device with the controls. When it is maxed out that is all it can give.


----------



## mickeydg5

spacerocker said:


> I see what you are saying - but in electronic terms, GAIN does not equal "an increase from one point to another". it means the multiplication factor of a circuit.
> 
> Suppose we have a circuit where for an input signal of 1V Peak-to-Peak, the output is 2V Peak to Peak. That circuit would have a gain of 2.
> 
> Now suppose we increase the input to 2V. The output will have gone up to 4V. Does that mean we have increased the gain? NO - because the gain which equals output voltage divided by input is still 2.
> 
> If we have a so-called "GAIN" pot on the input of the circuit I described above which can be turned up or down to control the signal level going in, then that pot is NOT strictly a GAIN control, as the GAIN of the circuit stays the same, irrespective of the level of the input!
> 
> A true GAIN control would increase the output of the circuit even if the input stayed the same
> 
> So I disagree with this statement "The potentiometer or other signal/volume control device whether called GAIN, PREAMP VOLUME, VOLUME, MASTER VOLUME, PPIMV, VVR, EPA, POWER SCALING or something else still controls the "gain" of the amplifier." - even though this is a common mis-conception!


Multiplication factor is built into the equation of a component's gain.

I see what you are getting at with the above. If you have a fixed gain/amplification factor then the output would be that times the input for that component.

The problem with that thinking is that you are not including the input and output loads being varied by the controls, the potentiometers. A load change on the device changes the gain of that component, that stage.

Controls like a potentiometer cannot increase anything. They can only attenuate, decrease, diminish.

So like you mentioned above when you "scale down an output" or signal then you are effectively decreasing the gain of the device/unit.
The gain of a unit/device:
input 300mVAC, output 300VAC, gain = 1000
input 300mVAC, output 30VAC, gain = 100
The differences in output are caused by variation of controls and the circuits themselves.


----------



## spacerocker

I think we will have to agree to disagree on this one. You _almost _agree with me, but......



mickeydg5 said:


> Multiplication factor is built into the equation of a component's gain.
> 
> I see what you are getting at with the above. If you have a fixed gain/amplification factor then the output would be that times the input for that component.



Agreed. The "multiplication factor" (i.e. the Gain) is set by the components in the circuit (e.g. the type of valve) and the components around it (e.g. Cathode resistor, etc..), NOT by the input signal strength (amplitude)



mickeydg5 said:


> The problem with that thinking is that you are not including the input and output loads being varied by the controls, the potentiometers. A load change on the device changes the gain of that component, that stage.



Whilst I agree that the load on the amplifier stage may have some small effect on the gain (and in linear gain stages, negative feedback reduces this effect), but he load from the subsequent stage stays the same - the so-called gain controls we are talking about are potentiometer at the *INPUT *of the pre-amp stage, power amp stage etc. Whilst they can vary the voltage into that stage the input current does not change much due to the high input impedance of a valve, so the gain stays almost completely the same. The GAIN control only increases the output because it increases the input!



mickeydg5 said:


> Controls like a potentiometer cannot increase anything. They can only attenuate, decrease, diminish.



Agreed. They are passive components. I don't think I said anywhere that a potentiometer can increase a voltage?



mickeydg5 said:


> So like you mentioned above when you "scale down an output" or signal then you are effectively decreasing the gain of the device/unit.



No. I was talking about the master volume pot. This scales down (i.e reduces) the signal from the pre-amp prior to going into the power amp. We are not decreasing the gain of the pre-amp, just reducing the amplitude of its output. The Pre-amp gain stays the same (as does the power amp gain).




mickeydg5 said:


> The gain of a unit/device:
> input 300mVAC, output 300VAC, gain = 1000
> input 300mVAC, output 30VAC, gain = 100



Here, you agree with me. Gain is output divided by input. But here you would have to be either talking about two different devices, or altering the circuit by changing the value of external components (e.g cathode resistors, etc) Marshall Amps do not have controls to allow you to do that.





mickeydg5 said:


> The differences in output are caused by variation of controls and the circuits themselves.



Agreed. The output is varied by the level of the input x the gain of the stage. The fundamental gain of the circuits cannot be changed by the controls on the amp. i.e. the "Gain" and Master volume controls can control the level of overdrive , and the overall volume of the amp. But the GAIN of the pre-amp and Power amp stages are unchanged. To look at in another way, with pre-amp GAIN, Channel Volume, and Master Volume up FULL (i.e. the amp flat out) you have the natural gain of the whole amp. Turning any of those controls down, just attenuates the signal at various points to make the amp quieter/less over driven etc....The GAIN control sets the level if signal INTO the pre-amp, the channel VOLUME (for multi-channel amps) pot sets the level of output from the pre-amp into the power amp, and the MASTER VOLUME pot sets the signal level into the power amp. None of those controls change the fundamental gain of those stages!

Final thought - to change the GAIN of a circuit, you have to change the characteristics of an active circuit (i.e. valve, transistor, etc...) This can only be done by changing external components (cathode current, feedback resistor, etc) changing the input level (e.g. using a potential divider) does not affect circuit characteristics like gain, etc


----------



## mickeydg5

@spacerocker
I agree with lot of what you posted.

I was just pointing out that the gain of a unit/device versus that of a component are different things, looked at a bit differently.

All I am trying to say is that the Mu/Amplification factor and the Gain/Voltage Amplification are not linear. Those change as the circumstances vary around the amplifying component.
AC signal strength/level input as well as AC load on the amplifying component affects its operation. A small input signal and greater load will decrease its efficiency, its amplification factor and its gain. It is a reactive component and has a gain curve.


----------



## spacerocker

mickeydg5 said:


> @spacerocker
> I agree with lot of what you posted.
> 
> I was just pointing out that the gain of a unit/device versus that of a component are different things, looked at a bit differently.
> 
> All I am trying to say is that the Mu/Amplification factor and the Gain/Voltage Amplification are not linear. Those change as the circumstances vary around the amplifying component.
> AC signal strength/level input as well as AC load on the amplifying component affects its operation. A small input signal and greater load will decrease its efficiency, its amplification factor and its gain. It is a reactive component and has a gain curve.



Yes - I get what you are saying, and I think we kind of agree?

I know gain can vary a bit depending on the signal strength, but I like to keep things simple, especially on forums and it is almost splitting hairs to say that the "GAIN" knob increases gain because the gain characteristics change slightly with a larger signal..90% of the reason the output from the gain stage gets louder/more distorted (depending on whether it is power amp or pre-amp we are talking about) - is simply because the input gets bigger, and the ouput is GAIN x Input....

I would hazard a guess that most people (and I used to be one of them until about 10 years ago!) think that the GAIN control actively changes the gain by modifying the *gain setting part of the circuit *- not just by varying the input level to a (mostly) fixed gain circuit. That's the point I was trying to make, really!


----------



## mickeydg5

I agree about the gain and distortion scenario. People confuse gain with distortion. They call it gain. The voltage gain is driven high enough to cause overdrive/distortion.
Then they call an amplifier with higher distortion/harmonics a high gain amplifier. There is no more gain in that amplifier as in another of the same power level but rather more overdriven stages which produce the distortion/harmonics.
They should call it an overdriven multi-stage amplifier or maybe optional stage amplifier since most have a cleaner channel along with varying other overdrive channels.

Yes we do agree. It is splitting hairs.

What is funny or interesting though is that gains curves are very much almost opposite of the audio taper curves found in our GAIN and VOLUME controls.


----------



## spacerocker

mickeydg5 said:


> I agree about the gain and distortion scenario. People confuse gain with distortion. They call it gain. The voltage gain is driven high enough to cause overdrive/distortion.
> Then they call an amplifier with higher distortion/harmonics a high gain amplifier. There is no more gain in that amplifier as in another of the same power level but rather more overdriven stages which produce the distortion/harmonics.
> They should call it an overdriven multi-stage amplifier or maybe optional stage amplifier since most have a cleaner channel along with varying other overdrive channels.
> 
> Yes we do agree. It is splitting hairs.
> 
> What is funny or interesting though is that gains curves are very much almost opposite of the audio taper curves found in our GAIN and VOLUME controls.



That's interesting....

Also some amps (like the JVM) Increase overdrive by lowering the plate voltage by using a higher value plate resistor, thus effectively lowering the threshold for clipping - and this is seen by some as "increasing gain"!


----------



## mickeydg5

spacerocker said:


> That's interesting....
> 
> Also some amps (like the JVM) Increase overdrive by lowering the plate voltage by using a higher value plate resistor, thus effectively lowering the threshold for clipping - and this is seen by some as "increasing gain"!


Wait, whaaaaat?
That does increase the overall gain of the tube circuit. In that instance the load of the tube circuit would be lessened therefore increasing amplification factor and gain.
It is also shown in the tube data and verified in tube manuals.

Are you screwing with me?


----------



## South Park

The jcm 800 has three stages . the first stage is the gain stage . The first Half is for gain ramped up signal.the second halve normal head room.so it clipped the signal. The second stage inverts the signal both sides are clipped no gain for second stage. The third is the phase splitter normal head room. Feeds the drivers grids.distortion is clipping.it is a balance of tone and crunch


----------



## mickeydg5

South Park said:


> The jcm 800 has three stages . the first stage is the gain stage . The first Half is for gain ramped up signal.the second halve normal head room.so it clipped the signal. The second stage inverts the signal both sides are clipped no gain for second stage. The third is the phase splitter normal head room. Feeds the drivers grids.distortion is clipping.it is a balance of tone and crunch


You should really specify which JC800 model if you want to make a case.


----------



## South Park

The original jcm 800 . It’s just not all about gain. It how the rest of the amp works the signal.


----------



## mickeydg5

South Park said:


> The original jcm 800 . It’s just not all about gain. It how the rest of the amp works the signal.


That is not a model designation and they all do not work the same.

Again, which model?


----------



## South Park

The 2204. The newer ones are different


----------



## mickeydg5

South Park said:


> The 2204. The newer ones are different


Please tell us how since a reissue is a recreation.


----------



## spacerocker

spacerocker said:


> That's interesting....
> 
> Also some amps (like the JVM) Increase overdrive by lowering the plate voltage by using a higher value plate resistor, thus effectively lowering the threshold for clipping - and this is seen by some as "increasing gain"!





mickeydg5 said:


> Wait, whaaaaat?
> That does increase the overall gain of the tube circuit. In that instance the load of the tube circuit would be lessened therefore increasing amplification factor and gain.
> It is also shown in the tube data and verified in tube manuals.
> 
> Are you screwing with me?



Yes - I've been back to check the equations - and you are, of course correct! - Increasing the value of the plate resistor does increase the gain!

But it also reduces the plate voltage (causing more clipping) - which was the explanation I had previously read.

So I think the summary is that increasing the plate resistor from the "traditional" value of 100K to 220K increases the gain AND clipping in that stage....


----------



## mickeydg5

spacerocker said:


> Yes - I've been back to check the equations - and you are, of course correct! - Increasing the value of the plate resistor does increase the gain!
> 
> But it also reduces the plate voltage (causing more clipping) - which was the explanation I had previously read.
> 
> So I think the summary is that increasing the plate resistor from the "traditional" value of 100K to 220K increases the gain AND clipping in that stage....


When explaining or giving details to these things I look at the big picture, usually everything included.
I have mentioned both AC and DC.
In the above statement mostly regards to DC operation is involved. However, the plate resistor affects not only DC but AC as well. The other resistors beyond the coupling capacitor also affect AC loading. All of these things work together in regards to exponentially raising and lowering the amplification factor and gain.

We are back to splitting hairs.  At higher signal levels there is much less difference in amplification factor and gain. At low signal levels the differences are greater and have a more drastic/exponential curve.

This is why I like an amplifier that provides a wider control range from clean levels to overdrive levels to higher distortion levels. I do not like an amplifier that is clean on 1 or 2, by 3 overdriven and four maxed out.


----------



## Valvelust

mickeydg5 said:


> Please tell us how since a reissue is a recreation.


It appears he isn't comparing to a 2204/2203 reissue rather the 2205, 2210, 4010, 4210 models etc...


----------



## Vinsanitizer

Gain is like where you had $2, you invested it, and now you have $20.
But that's low gain. I'm not sure I can accurately define high gain.


----------



## mickeydg5

Vinsanitizer said:


> Gain is like where you had $2, you invested it, and now you have $20.
> But that's low gain. I'm not sure I can accurately define high gain.


Only rich, greedy people achieve high gain.


----------



## Vinsanitizer

mickeydg5 said:


> Only rich, greedy people achieve high gain.


Ok, so yeah - that explains why I can't define high gain.


----------



## kinleyd

Vinsanitizer said:


> Gain is like where you had $2, you invested it, and now you have $20.
> But that's low gain. I'm not sure I can accurately define high gain.


Hee hee, Vin, you up to no good again?


----------



## Vinsanitizer

kinleyd said:


> Hee hee, Vin, you up to no good again?



No!

... ok, yes.  How've you been bro?


----------



## kinleyd

Vinsanitizer said:


> No!
> 
> ... ok, yes.  How've you been bro?


Been good Vin, thank you. Been focusing on the family (kids school/college, etc.) and practicing guitar more than providing my unqualified comments on MF and TGP. In a couple of weeks I hit my sixth anniversary since picking up the guitar! In short, it's been wonderful : )

Do hope all is well with you too.


----------



## Vinsanitizer

kinleyd said:


> Been good Vin, thank you. Been focusing on the family (kids school/college, etc.) and practicing guitar more than providing my unqualified comments on MF and TGP. In a couple of weeks I hit my sixth anniversary since picking up the guitar! In short, it's been wonderful : )
> 
> Do hope all is well with you too.


Yup. Been hanging out on the forum a bit more lately and setting aside some time to play guitar. Sometimes I just get tired of working all the time.


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## mickeydg5

I hate working.
There are much better things to do.


----------



## GT08

Output/input.

Rock n' roll


----------



## myersbw

mickeydg5 said:


> I hate working.
> There are much better things to do.



And, THAT...is why I'm retiring at the end of next year after 34 years at the same place. Lol...well, only to do half-time amp work (which is like 1/5 time now). Lol, something needs to offset the insurance costs??? :O


----------



## cruisemates

I first learned about gain as a recording engineer, which I think makes more sense. A typical dynamic mic is a passive device and so its current is extremely low - so it needs a preamplifier just to get it up to usable (nominal) levels. A mic is typically about -45 dBu - and the goal is to get it up to near unity, or 0 dBu - hence GAIN is in the mic preamp.

As the gain is brought up the engineer adds EQ, and other units that can add or subtract from the unity level. Hence channel faders are used accordingly. EQ can add or subtract from the unity level, A compressor has an input stage (gain) that hits the compression circuit, and it has an output volume stage that sets its level (+ or - unity) to go on to the next stage.

As all channels get mixed together they are summed at the master faders. Once again your total dBu current may be + or- unity, and so the master faders may be adjusted accordingly. Keep in mind the master faders feed the tape decks, or DAW interface, or PA system. They need to be not too low or too high for that next level of "gain."
Too low and you get noise (signal to noise ratio), too high and you risk hitting the top level of output that component can deliver and you get undesirable distortion and a loss of "clean headroom."

SO - a better engineer will set his master faders at unity, and NOT touch his mic preamp gains, but will adjust the overall volume of the mix with the channel faders to make his master faders (set at unity) feed the next interface with the correct amount of gain for whatever they are controlling. This is why all old mixers have "master" output VU Meters - that should always be set to top out near 0 dB, or unity level.

SO - easiest definition: gain is the "input" signal going into a device and "volume" is the level of output signal from a device set to feed the next stage.

Guitar Amp Gain - this is a different concept. The idea of input as gain and output as volume remains the same. BUT in a guitar amp, the gain is intentionally boosted beyond simple unity - it is pushed far past that level for one simple result - saturation. Tubes and certain other transistor-based components (or diodes) can only pass through a limited amount of current. The harder you push them the more they saturate (clip) which flattens the waveform and gives us what we call "distortion" in amps. Except that it is intentional so we call it "overdrive." In this situation, the overall volume does not increase proportionally to the amount of increase in gain, but the saturation will increase.

The common notion is tubes saturate by adding even harmonics (sound nicer) and silicon saturates with more odd harmonics (not quite as pleasing) but the end result is often the same. Some overdrive pedals are built to boost the "gain" going into a guitar amp's preamp tubes to make them saturate (IE: the "tube screamer" does not contain any tubes). Some tube amps "love pedals" meaning your preamp tubes are susceptible to clipping just by hitting them harder than the amp alone can hit them. Not all amps love pedals.

Other overdrives use internal components to recreate the sound of overdriven tubes but also have volume output controls so you can get that overdriven tube sound from any amp without making it distort. They usually use either diodes (which will clip a sine wave when overdriven), or they overdrive certain transistors (FETs are very good for this, since FETs were designed to replace tubes), or they overdrive the inputs on IC chips. Many pedals use all of the above.

TL/DR "Gain" in mixing is about keeping your levels near unity for the best results in both signal to noise ratio and headroom = usable dynamic range. Gain in guitar amps (or pedals) is how far you can drive any component that is prone to saturation (clipping the sine waveform) to create an "overdriven" sound. Volume is generally just the output level of any given device regardless of how much gain it receives.


----------



## mickeydg5

Gain is basically defined in basic electronics. Do not over think it nor try to make it something it is not.

increase the amount or rate of

Gain is just the ratio of two quantities. When talking about circuits, it's almost always the ratio of some measurement of the output of a circuit or component to its input.

a measure of the increase in signal amplitude produced by an amplifier, expressed as the ratio of output to input.

Keep it simple.


----------



## myersbw

mickeydg5 said:


> Gain is apply defined in basic electronics. Do not over think it nor try to make it something it is not.
> 
> increase the amount or rate of



That's exactly right. Gain is an increase (can be interpreted as any quantity) vs. loss which is...duh...a decrease.


----------



## cruisemates

Another way to define it is with technology - when a tube or transistor takes an input and works to increase the current for the output, that is gain. The other question is "what is unity gain vs. overdrive gain?" 

1. is for Hi-Fi functions or recording techniques
2. is for guitar pedals or amp 12ax7 preamp stages


----------



## JP2036

{>}


----------



## JBA

Russelll said:


> Very good, I think I'm going to like this place. . The simple answer to "What is gain?" could be, simply put, "the ratio between input and output. A gain of 1, also known as unity gain, is when input voltage is equal to output voltage. A gain of 2 is a 1:2 ratio, and so on.


Nailed it! I’ll add “between any two selected points” for Voltage, Current, and/or Wattage. Can you call a variable pot on a guitar amp “gain” then distort the signal later.. apparently that’s how it went down. ;-)


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## datavomit

momma says gain is like magical rays of sunshine


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## mickeydg5

Its a detergent.


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## JBA

mickeydg5 said:


> Its a detergent.


This must be Fender’s soap of choice, cause thing come out pretty clean when you use Gain.


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## Spyderg0d

Gain is signal strength within electronic parameters, volume is end result physicial loudness of the electronic signal. 
Physical Speaker distortion beyond a speakers capabilities of clearity is not Gain like some think. 

Gain can result in volume differences IF the Gain IS controlled WITH the volume control in the circuit. They can be the same in a circuit or sperated in control and seperate controls in an end result.


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## Clayton Custom Cabs

Imitation is the sincerest form of flattery, right. But, if you don't quote your source I think it's called plagiarism?


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## JBA

Clayton's Custom Cabs said:


> Imitation is the sincerest form of flattery, right. But, if you don't quote your source I think it's called plagiarism?


“Imitation is the sincerest form of flattery” ...I know I’ve heard this quote before.


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## Clayton Custom Cabs

One of my father's favorite quotes, he used many but never told me where they came from...if he knew.


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