# Super Bass/Super Lead: What Are The Differences?



## 5er driver

For guitar use……assuming they are both using the same pre amp and power tubes, is there a circuit/component and tonal difference between the two amps? I’m asking specifically about the ’67 –’81 MKII 1992 JMP Super Bass and the same era MKII 1959 JMP Super Lead. I’ve read that the Super bass has more headroom, not something I’m really looking for though. And the differences between the two would also apply to the ’67 –’81 50 watt models MKII 1986 JMP Bass and MKII 1987 JMP Lead? 

Thanks.


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## jcmjmp

Have a quick look at the schematics. The differences are minor.


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## rykus

the super lead changed more while the super bass stayed the same from its inception(if thats a word) till they went circut board, also i noticed my SL has two bright /two normal imputs so the sound can be changed more with the volumes of I and II if jumpered while the SB just gets dirtier! my SL is a '70 but i've never played another so i don't now if thats true for all 67-81, i like the SB and my plexi bass 50 alot and had trouble getting adjusted to the SL till i learned to turn vol I lower than II but maaybe some nice tubes and a bias will help. i do know my tech put lead value parts in the plexi when he got it working and it sounded too bright, but once again CP tubes.


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## bfglp

5er driver said:


> For guitar use……assuming they are both using the same pre amp and power tubes, is there a circuit/component and tonal difference between the two amps?




the only difference between them are four capacitor values and one resistor value.


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## 5er driver

Thanks guys. I'm looking for a JMP 1959 or 1987 and saw some 1992 bass heads on the fleabay and was wondering about the headroom/tonal differences as well. Do the SBs sound real different compared to SLs? If there's just a parts difference of 5 components it shouldn't be difficult to convert an SB to an SL.


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## rykus

really easy to switch between the 2, my tech let me try both and took him only minute's too swap... you might be supriesed though super bass is rad definatly not what i would call " clean" headroom, i'd say just as much crunch with out the ice pick highs.... great for metaly drop tuned cause you can dime the presnce and treble with less squeal and feedback to get more gain. my 73 super bass 100 was way cheaper than lead, still 67 design ptp and is crazy loud, it wants to destoy speaker's and should be used with caution...


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## MartyStrat54

I think a Super Bass sounds fantastic for metal guitar. With the right speakers and cab, it is an ass ripper.


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## LesPaul Signature 74

How close in sound/tone would a Super Trem/Super Lead come to a Super Bass if I the bright cap was clipped on the high channel? I find my Super Trem to be very bright at lower volume settings.


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## rykus

i not a tech but i think clipping the bright cap is a mod for reissues... once again not a tech so take it with a grain of salt but i think you have to swap some caps or resisters??? to a different value. a good tech would be able to tell you exactly though, don't wanna chance destroying your amp. mine let me try both. ive never played a tremelo one, don't they have a 4th tube aswell probly a bit different. i like the bass sound, but as i mentioned i like my pre amp running hot for extra gainy sound, the lead you have too remember settings instead of 10 10 10 10 7 7 , gets nice overtones/feedback though!


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## Reginald

U could try to modified it in a shared cathode in v1 plugging pin 3 with pin 8....this should create a 'bigger' 'fatter' sound


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## Gtarzan81

*Re: But in each*



gjhffgkj said:


> But in each wow gold variable of Socialism that appeared from near 1900 onwards the aim of establishing independency and equivalence was solon and more openly so stressed unfreedom and inequality as it was struggling for defamation and pay lip-service to their commonwealth, had wow gold ever prefab use of such position as freedom forsaken.



But I dont like spam!


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## Adwex

No need to quote the spam, just report it.


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## Gtarzan81

Adwex said:


> No need to quote the spam, just report it.



Understood. Feel free to delete those then, if desired.


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## gepetto33

MartyStrat54 said:


> I think a Super Bass sounds fantastic for metal guitar. With the right speakers and cab, it is an ass ripper.



With what pedal might you suggest? Or perhaps a gain mod?


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## V-man

LesPaul Signature 74 said:


> How close in sound/tone would a Super Trem/Super Lead come to a Super Bass if I the bright cap was clipped on the high channel? I find my Super Trem to be very bright at lower volume settings.



I just read this late in the game, and I am refering to my JCM 800 1992, so take those differences FWIW:

1. Mine does not have a master volume, and tube breakup doesn't seem to register until you push it past 8. It is an extremely clean sounding amp that needs to be dimed or pedal boosted. I don't know about earlier 1992s but I find it hard to believe that the JCM 800 didn't come with a master volume, but earlier ones did (though stranger things have happened)

2. What makes the 1992 unique to me, is that it probably has the most impressive EQ made on an "old-school" Marshall. In addition to B-M-T, there is "slope" and "mid sweep" which together make the face a sophistocated 5-band EQ. Bass response borders on criminal negligence for Marshall. It goes to 5 and 3 is extreme. It also has a pretty sick amount of treble on it too.

So take my post with a grain of salt for having no experience with older super bases and super leads, but If the older one is built or equipped anything like the JCM 800 series, it's a totally different animal.



gepetto33 said:


> With what pedal might you suggest[FOR METAL]? Or perhaps a gain mod?



I have just been playing with mine for metal recently. Bear in mind I swapped the 6550s with KT88 and run it through a quad of V30s. If you can open the amp up all the way or attenuate it, you can actually get by with a MXR 10-band and just engineer your own metal sound with a little gain boost on the slider - that and a noise gate was all Kerry King used with his KT88-driven 2203. If you are trying to play bedroom volume on the monster then the nice thing (again at least regarding the JCM 800 Superbass) is that it will take any pedal amazingly. 

A lot of people use Boss DS or OD, some use a RAT, etc. I got a reissue MXR Distortion + for $20 (something that's more OD than DS), which newbs hate for the sound and MXR fans hate for the derrogation from the original Distortion tone, and I can get some great tones with the 10 band. My advice is to find a used MXR 10 band first. Then get any dirt pedal you think appeals to your ears or wallet. Hook the two together and between the amp EQ the MXR 108, I'd wager it's impossible that you can't get some usable tones for metal with any dirt pedal.


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## Reginald

While,what differences are there between Super lead and Super Tremolo?
Can a ST to be transform to SuperLead? How many caps should u replace? While about transformers and voltage.....are them equal/the same ? or super Tremolo owns different Trannyes and Voltage? thank u
p.S. ST seems lower volume than SL/SB...why?


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## Richman1

rykus said:


> the super lead changed more while the super bass stayed the same from its inception(if thats a word) till they went circut board, also i noticed my SL has two bright /two normal imputs so the sound can be changed more with the volumes of I and II if jumpered while the SB just gets dirtier! my SL is a '70 but i've never played another so i don't now if thats true for all 67-81, i like the SB and my plexi bass 50 alot and had trouble getting adjusted to the SL till i learned to turn vol I lower than II but maaybe some nice tubes and a bias will help. i do know my tech put lead value parts in the plexi when he got it working and it sounded too bright, but once again CP tubes.


From what I've been told, The bass circuit stayed the same as the plexi's , and the lead models changed a bit into the 70's....A bass circuit in 70,71 and 72 stayed true to the plexi circuit....I hope that is true, I just bought a 1972 50 watt bass head that was modded to be a 68 plexi lead amp in every detail. It sounds real good. Please correct me if I'm wrong....I'm not a tech....


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## Bunnest

that amp is not a 1992 super bass, its the marshall Bass Amp JCM, totally different beast. The 1992 is like the 1959, your amp, the JCM Bass amp, is NOT, HENCE THE CLEAN TONE UP TO THE TOP...its made for bass. think Trace Elliot tone, not Hendrix at Monterey


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## MartyStrat54

gepetto33 said:


> With what pedal might you suggest? Or perhaps a gain mod?



There's many good pedals that would work. I have a friend in Phoenix that has a 1975 Super Bass and he runs Boss pedals with it. I sent him a tube set with a high gain NOS for V1 and V2 and a special, unbalanced tube for V3.


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## chuckharmonjr

Marty, I am very curious because you are the tubemiester...why an unbalanced tube?


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## MM54

When it splits the signal for the push/pull poweramp, the difference creates more harmonics in the final signal :cool2:


(See? I do pay attention! )


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## Anthony King

MartyStrat54 said:


> There's many good pedals that would work. I have a friend in Phoenix that has a 1975 Super Bass and he runs Boss pedals with it. I sent him a tube set with a high gain NOS for V1 and V2 and a special, unbalanced tube for V3.


Marty, I've got a tube question. I've got a '74 Super Bass 100W and currently running Tung-Sol 12AX7As in all 3 preamp slots. I have a Genelex B759 gold pin 12AX7A on its way. What is your recommendation for best tone - which tubes should I place in V1, 2, 3? FYI..I was going to place the Genelex in V1 and leave the other 2 untouched.


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## Kris Ford

Anthony King said:


> Marty, I've got a tube question. I've got a '74 Super Bass 100W and currently running Tung-Sol 12AX7As in all 3 preamp slots. I have a Genelex B759 gold pin 12AX7A on its way. What is your recommendation for best tone - which tubes should I place in V1, 2, 3? FYI..I was going to place the Genelex in V1 and leave the other 2 untouched.



In my '74, I run a Tungsram, a I63 yellow label Mullard, and a long plate Mullard in the PI, all NOS..makes a *huge* difference to me, no hype.


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## Anthony King

Kris Ford said:


> In my '74, I run a Tungsram, a I63 yellow label Mullard, and a long plate Mullard in the PI, all NOS..makes a *huge* difference to me, no hype.


Thanks Kris! My problem is finding these NOS tubes. Where is your source?


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## Kris Ford

I was gifted a couple, and scored a long plate Mullard from Tube Depot.


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## Joshabr1

With shared cathode amps the channels are much closer in sound than with the split cathode lead amps. If your looking for your kossoff Clapton early Hendrix that's what you want. Not as Grindy and top end sounding as the lead amps. Also to be noted the negative feedback resistor and what tap it is hooked to plays a big role in the break up character. 100k on the 4 ohm tap is quite a bit more chewy sounding that say 27k or 47k on the 16ohm tap or speaker jack. I'm fortunate to live in a place to where I can play my amps dimed up. Maybe that's why I prefer the cleanest amp possible. Right now I have a pa spec head with 27k neg hooked to 16 ohm tap. My favorite old Marshall ever.


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## Anthony King

Kris Ford said:


> In my '74, I run a Tungsram, a I63 yellow label Mullard, and a long plate Mullard in the PI, all NOS..makes a *huge* difference to me, no hype.


I've got 2 Mullard I61s en route. I'm going to put those in V1, V2..and put a Genelex in V3. I'm curious to see how these affect the tone vs the Tung-sol RI tubes I've been running for the last year.


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## Joshabr1

Anthony King said:


> I've got 2 Mullard I61s en route. I'm going to put those in V1, V2..and put a Genelex in V3. I'm curious to see how these affect the tone vs the Tung-sol RI tubes I've been running for the last year.[/QUOTE
> 
> 
> If you have been running cp tubes and switch to i61 Mullards it won't take but a second to hear a sweeping and vast change to the good. I also recommend a good long plate tube like a Raytheon or telefunken in v3


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## Joshabr1

U may also try a long plate tube in v2. I prefer that over 2 i61s. I61 in v1 Mullard long plate in v2 and telefunkin in v3 is about as good of a pre amp set up I've ever heard. And I've tried them all!!!!


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## tone seaker

Joshabr1 said:


> With shared cathode amps the channels are much closer in sound than with the split cathode lead amps. If your looking for your kossoff Clapton early Hendrix that's what you want. Not as Grindy and top end sounding as the lead amps. Also to be noted the negative feedback resistor and what tap it is hooked to plays a big role in the break up character. 100k on the 4 ohm tap is quite a bit more chewy sounding that say 27k or 47k on the 16ohm tap or speaker jack. I'm fortunate to live in a place to where I can play my amps dimed up. Maybe that's why I prefer the cleanest amp possible. Right now I have a pa spec head with 27k neg hooked to 16 ohm tap. My favorite old Marshall ever.


could you explaine chewy i have often wondered about the sound differences on NFB where the wire is hooked and resitor value. Thks


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## Joshabr1

By chewy another world would be grindy. Marshall used 3 resistor values for the negative feedback. 27k 47k and 100k. They will be hooked to one of the three taps or the speaker jacks. The cleanest most open sounding would be 27k on 16ohm tap. So 100k on the 4 ohm tap would be the grindiest sounding. I personally like 27 or 47k on the 16 and 8 ohms respectively. It's a taste thing really.


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## tone seaker

Joshabr1 said:


> By chewy another world would be grindy. Marshall used 3 resistor values for the negative feedback. 27k 47k and 100k. They will be hooked to one of the three taps or the speaker jacks. The cleanest most open sounding would be 27k on 16ohm tap. So 100k on the 4 ohm tap would be the grindiest sounding. I personally like 27 or 47k on the 16 and 8 ohms respectively. It's a taste thing really.


so whats the difference in sound between tap and out put jack


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## Trapland

tone seaker said:


> so whats the difference in sound between tap and out put jack



I'll take a whack. When connected to a tap, your NFB remains consistent regardless of what your impedance setting is. You can run any cab config and maintain the same NFB.

When connected to the speaker jacks, the NFB changes when you change impedance settings. I.E., cleaner with a single 16 ohm cab and much crunchier with a 4 ohm cab (if you had one).


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## tone seaker

Trapland said:


> I'll take a whack. When connected to a tap, your NFB remains consistent regardless of what your impedance setting is. You can run any cab config and maintain the same NFB.
> 
> When connected to the speaker jacks, the NFB changes when you change impedance settings. I.E., cleaner with a single 16 ohm cab and much crunchier with a 4 ohm cab (if you had one).



so why would some one want it on the speaker jack. Seems like the imp selector would be the way to go so it would not vary when adding more cabs for more volume?


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## Trapland

tone seaker said:


> so why would some one want it on the speaker jack. Seems like the imp selector would be the way to go so it would not vary when adding more cabs for more volume?


I agree, the selector seems better. I thought I heard Marshall put them on the jack occasionally. The only reason I can think of using the speaker jack is if you had a 4x12 that was switchable from 4 to 16, then you could use the amp impedance selector to choose your favorite amount of NFB without opening the amp. Or just set it and get down to playing guitar.


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