# What Kind Of Pots Do You Prefer In Your Amp Build?



## SirArcsAlot

I was wondering what you guys who build your own amps perfer for pots. linear or logarithmic. I used all linear pots on my plexi build to seemingly great effect. I get extremely precise control over all of the EQ knobs and volume knobs too, and my volume is a volume control instead of an on/off switch.


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## ampmadscientist

Precision Electronics Canada use audio taper for amps like a Marshall.
https://www.tubesandmore.com/products/potentiometers_0?filters=Brand=Precision Electronics


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## Metroman

PEC are what are in my Metropoulos Limited Edition GMP45. Metro uses those on their builds.


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## Oatie

I believe his question is,
Do you use Audio or Linear pots in your amps.

How does a linear taper pot differ from an audio taper pot? With a linear taper the resistance changes evenly with the degree of rotation; at one quarter rotation the pot should read around 250K ohms, at half rotation the pot should read around 500K ohms etc. An audio taper pot changes very gradually; the ohms read pretty low until you start getting into the last 15% or so of rotation and then it increases very rapidly. 


The larger Fender amps used the Linear Vol Pots on the Tweed Twin, Bassman, Pro, Super and Bandmaster. These amps start to sound good just before the 1/2 volume levels because the LIN pots deliver the goods more gradual than the Audio log pots.


Here is a pic of my Tweed Twin, you can see they have the 1 Meg LInear Vol Pots.

All the schematics Fender has shows they used the Audio taper Vol pots, but it';s not true. All the amps I mentioned above use the LIN Vol Pots.

Keith Richards knows this, and this is why he loves the Tweed Twins, the taper on the LIN pots works better at lower volumes. he Audio Taper pots don't work well until you almost dime the amp, this is why most Marshall users need a MV or an Attenuator.


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## Biddlin

Malibu Mutana, Sativa weighted hybrid. Oh, sorry. Wrong thread...
;>)/


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## SirArcsAlot

Great explanation, Oatie. I noticed a greater effect on my EQ controls with the Lin pots. It is noticeable on the volume pots, though not as obvious as on the EQ part.


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## ampmadscientist

PEC audio is not the same as other audio tapers.
It's spread out more so the adjustment range is wider from 0-10.
It's a specially developed taper. That's what I really like about those controls, more adjustment range.
It's a lot different than consumer grade.
It's really more like reverse logarithmic...

I never had a control that worked this well in a tube amp before.

I am 100% sold, I will use PEC in all builds.



It's military grade, stainless steel, built to last.


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## Vinsanitizer

if I want mids I want mids. That means AAAAAAWWWWWWWWW. I don't want mids that add KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK like thy do on the JCM2000. You can turn the mids, treble and presence OFF on those JCM 2000's and still hear, KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK.


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## coldengray

Germino has a strong opinion on this topic, though I can't recall which he uses - linear or log.

As for PEC, they are a high quality pot but eventually will get scratchy and you cannot clean them because they are sealed. For this reason I now use CTS, though I have used PEC plenty of times too. Also you can't solder a ground bus to the back of PECs, if you are aiming for a vintage correct Marshall build.


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## mickeydg5

Taper is only a measurement.
If you close your eyes and dial in what you want it does not matter if it is linear or taper.
People are so fickle.

A quality potentiometer usually trumps a cheaper potentiometer.


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## ampmadscientist

coldengray said:


> Germino has a strong opinion on this topic, though I can't recall which he uses - linear or log.
> 
> As for PEC, they are a high quality pot but eventually will get scratchy and you cannot clean them because they are sealed. For this reason I now use CTS, though I have used PEC plenty of times too. Also you can't solder a ground bus to the back of PECs, if you are aiming for a vintage correct Marshall build.


You can take it apart and clean it just like any other.
Or, make a hole in the case to spray it.
Soldering: you need the right equipment to solder to it, just like any other. I'm sure a radio shack iron will not work on it, but a professional one will.


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## ampmadscientist

mickeydg5 said:


> Taper is only a measurement.
> If you close your eyes and dial in what you want it does not matter if it is linear or taper.
> People are so fickle.
> 
> A quality potentiometer usually trumps a cheaper potentiometer.



The range of adjustment is wider on a good one.


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## v846

ampmadscientist said:


> You can take it apart and clean it just like any other.
> Or, make a hole in the case to spray it.
> Soldering: you need the right equipment to solder to it, just like any other. I'm sure a radio shack iron will not work on it, but a professional one will.




I built two amps using PEC's & both sets became scratchy so I drilled a hole to clean them , its works OK but no more PEC for me. Can also work the pot & sometimes they'll shut up.
http://i270.photobucket.com/albums/jj105/v846/JTM45 Clone/DSC04625.jpg

CTS or Alpha are fine, can clean them & easier to solder the backs if one wants.

FWIW here are lugs available for PEC's if one wants the buss without soldering to the pot.

http://i270.photobucket.com/albums/jj105/v846/Express/buss_zpsb3hmehto.jpg


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## stickyfinger

ampmadscientist said:


> PEC audio is not the same as other audio tapers.
> It's spread out more so the adjustment range is wider from 0-10.
> It's a specially developed taper. That's what I really like about those controls, more adjustment range.
> It's a lot different than consumer grade.
> It's really more like reverse logarithmic...
> 
> I never had a control that worked this well in a tube amp before.
> 
> I am 100% sold, I will use PEC in all builds.
> 
> 
> 
> It's military grade, stainless steel, built to last.


They are nice pots for sure. But worth the money? Not really IMO for classic builds anyways. Wrong wattage, wrong composition. The taper is typically 10% half way.. not so sure I understand this special taper you mention?

CTS Vintage are probably the closest to the vintage pots.


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## ampmadscientist

Real vintage amps used mil grade, similar to PEC.
These were always sealed...
(as in really vintage, not pretend vintage...or "reissue" vintage)
CTS came way after that.
CTS is consumer grade.

Somebody's been using the word "vintage," a little too loosely.
"Vintage" is being used as a sales tactic.

Mil pots were designed to survive on a battle field. You will see that the case is stainless steel etc...
Knobs: the set screw needs to be steel. Brass set screw will be eaten by the steel shaft, and does not survive.

Yes it's worth the money because it's real solid hardware.

In a specially developed audio taper, it's nothing like a CTS pot. The more you look into it, you will see that you get what you pay for.


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## stickyfinger

To each their own but Marshall used CTS pots in their amps. Handwired amps, as in vintage amps.


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## sloan_amps

Marshall and Fender both used CTS pots in their amps...I have all original '60s models of both with CTS from the factory. Therefore, they are good enough for me. Many newer Marshalls used Alphas as well.

As far as the OP, I use linear taper for treble, mid, & presence controls, but logarithmic for all others.


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## fusionbear

I use PEC pots, but I open them up and clean them and reassemble. It is not hard to do and this was a tip given to me by George Metro. I can't stand soldering to the back of pots. I much prefer a ground buss.


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## v846

fusionbear,


Cool idea,I've done this with scratchy PEC's but not new before going into an amp, what do you use to clean them with?


Thanks,

David


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## ampmadscientist

v846 said:


> fusionbear,
> 
> 
> Cool idea,I've done this with scratchy PEC's but not new before going into an amp, what do you use to clean them with?
> 
> 
> Thanks,
> 
> David


It's better to use Deoxit G-100, which lasts the longest.


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## ampmadscientist

sloan_amps said:


> Marshall and Fender both used CTS pots in their amps...I have all original '60s models of both with CTS from the factory. Therefore, they are good enough for me. Many newer Marshalls used Alphas as well.
> 
> As far as the OP, I use linear taper for treble, mid, & presence controls, but logarithmic for all others.


Some builders want something better than CTS.
Having used both, I would go for PEC.
CTS is basically consumer grade. PEC is professional grade...
What manufacturers use...is generally the cheapest thing that will do the job. Good pots are too expensive to use in consumer production.
But you will however see good ones used in military / medical equipment.


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## v846

ampmadscientist said:


> It's better to use Deoxit G-100, which lasts the longest.


Thanks for the tip


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## sloan_amps

ampmadscientist said:


> Some builders want something better than CTS.
> Having used both, I would go for PEC.
> CTS is basically consumer grade. PEC is professional grade...
> What manufacturers use...is generally the cheapest thing that will do the job. Good pots are too expensive to use in consumer production.
> But you will however see good ones used in military / medical equipment.



If that's what you prefer, then that's great...everyone has their preferences. I personally prefer CTS and know they are a quality product at a good price point. CTS are easier for me to obtain and be able to specify the tolerance I need. By the way, not all CTS are created equal. Like most companies, they have different grades and tolerances, such as the fact they offer them with plastic, brass, or steel shafts and commercial customers can specify anywhere from 1%-20% tolerance, so I know they are not all merely "consumer grade."

In 20+ years of using them in my amps without failure, plus the fact that I have amps that are 50+ years old with the original CTS pots still in them, I feel they're more than adequate for that application and therefore I don't feel the need to drive up my cost of production if I don't need to. Additionally, they are 100x better than what most off the shelf major amp companies use today, which like you said, are often cheap alternatives.

I'm not building military or medical equipment so using PEC isn't a necessity for me, although I still will guarantee my amps are built to last a lifetime.


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## coldengray

Sloan - agreed. Taking apart pots to clean them (before a build or after) is not something that interests me. Especially when a ground bus is involved.


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## stickyfinger

Agreed these are just guitar amps. Not precision military or medical equipment where that application I could understand a military spec pot. 11$ for a variable resistor? Probably wont ever again. And I don't like the way they turn!


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