Using MV amp like NMV?

billando

Whats the thoughts on keeping the master volume on 10 and using the preamp for volume just like a non master amp? Does this work or are they just not designed for that and sound terrible?

Got thinking of this yesterday watching a video of paul weller playing changing man. I believe he used a marshall 2100 lead and bass 50w combo which is a non master volume amp. I have a marshall 2104 50w master volume from same era....would this work?

mark_jwedge

I am having a play with using my amp like this at the moment. I have a Top Hat Emplexador 50 which is a 68 Marshall plexi with a master volume and a few switches to toggle various bright cap options. 

I haven’t got the master fully up but it’s wound round to 3 o’clock. There is a little more background noise but nothing that is intrusive at home and makes no difference live. 

The clean sound is glorious but the seemingly infinite headroom and dynamic range do mean that your playing technique needs to be pretty tight but live it’s great to be able to sit back or make certain licks/phrases pop out just by how hard you pick. 

Along those lines it took me a long time to balance the volumes of all my pedals when running the amp this way but I think I have it now.

Overall the clarity, punch and dynamics when playing live is fantastic. It’s much less forgiving to play but I think the trade off is worth it.

I’m enjoying it and will keep going with it for now at least.

ICBM

The 2104 with the MV on 10 and using the Low input is not *that* far away from a NMV Marshall, but it's still not exactly the same - it has slightly less gain and a bit thinner a tone in my opinion. The High input is significantly different as it has one extra gain stage.

Personally I wouldn't worry about trying to get it the same - in my opinion the 2104 is one of the very best-sounding of all Marshalls however you set it... although my personal 'magic' settings are just to whack the preamp volume up full along with the bass, put the master volume, treble, middle and presence all on 6 and control it from the guitar. I prefer the extra bite that the High input has over the Low no matter how it's set - I can get good sounds with the MV well below 6 too, you just need more mid and less presence usually.

billando

You say the high input has an extra gain stage but couldnt this just be compensated for by keeping the preamp lower if the master is at full? 

Im not sure about my 2104 tbh. Seems like its always thin in my band context unless i use an attenuator to get the master up to at least 5. I have a 4010 with the same speaker (g1265) that seems to have more balls. 

ICBM

billando said:

You say the high input has an extra gain stage but couldnt this just be compensated for by keeping the preamp lower if the master is at full?

Not really, it adds 'more' - a bit more harmonic distortion and changes the EQ a bit. The two circuits aren't the same.

billando said:

Im not sure about my 2104 tbh. Seems like its always thin in my band context unless i use an attenuator to get the master up to at least 5. I have a 4010 with the same speaker (g1265) that seems to have more balls. 

Have you tried turning the bass and mids up full and keeping the presence and treble low? I've always found them chunkier-sounding than the 800s and 900s, even with the MV as low as 2 or 3.

It could also be biased too cold or otherwise need attention - a lot of them came with no screen resistors originally so they draw more screen current, which then results in them biasing too cold if you take the measurement via a bias probe in the cathode connection. It's not good for the valves either...

billando

I have been doing that (bass, mids full and treble, presence low) with my 900 lately with great effect. I havent tried it with the jmp but i will when i get a chance. My jmp feels like it has far too much gain to me....someone said on the amp there was a footswitchable "boost" option....i thought this was rubbish but when i looked there is something there...i connected a footswitch but when i pressed it it sounded really weak and horrible. Im confused now....maybe that was a mod someone did. When this chaos is over ill send it for a thorough check over.....oh and it also squeals with the master high...even after i changed all valves...aaaargh

ICBM

A JMP 2104 does not have any boost function or anything that can be footswitched, so it sounds like it's been modded - in which case all bets are off as to whether it sounds the way it should or not.

Unless you connected the footswitch to the second speaker jack - which I assume you would be aware enough not to! - but if you did it would indeed make the amp sound strangled and weak, even if you got much sound out at all...

I came to the conclusion a very long time ago that the only worthwhile mod for these (apart from reliability ones like the screen resistors) is a simple FX loop - in every other case they try to make the amp into something it isn't and ruin the natural tone of them.

billando

ICBM whats your opinion on keeping preamp low and master high on amps such as 2104 and jcm 800 4010? Do you think cos theres not so much signal going to the power valves it can sound a bit weak or thin? Even for classic rock?

ICBM

billando said:

ICBM whats your opinion on keeping preamp low and master high on amps such as 2104 and jcm 800 4010? Do you think cos theres not so much signal going to the power valves it can sound a bit weak or thin? Even for classic rock?

I don't really like the sound of them with the preamp volume low, and I'm not a big fan of the Low input either, unless you need a strictly clean sound - both these sound a bit thin to me. I prefer to use the High input, with the preamp volume above halfway, and control it from the guitar. In fact, my favourite setting is just to turn it up full . This is not an amp I would pick if I needed a truly clean sound.

I don't have much of a problem getting a decent tone with the master volume low - although there is a definite change when it goes above about 6 and the power stage starts to overdrive as well. Try not to get hung up on things like 'signal going to the power valves' - that's not really what affects the tone of an amp when they're not overdriven, it's much more to do with things like bright caps on gain controls and the components surrounding preamp valves.

For what it's worth the Low input is not the same as a non-MV Marshall, which is fuller and richer-sounding because the preamp valve is configured differently - for clean I think these sound far better.

If I remember rightly your 2x12" combo isn't a 2104 anyway though...

billando

I never mentioned using the low input somebody else did i think. Not enough grunt there for me. Yes my JMP is actually a 2144 which has a footswitch to turn on the boost. With the boost off it is a little lame i think. I have the jcm 800 4010 though which is a great little amp. Problem i seem to have is both amps (but especially the jmp 2144) sound amazing at practice alone with master lowish and gain high but sound thin in a band setting. I find getting the master above 5 thickens it up and this makes it sound better in the band mix (unmiced). Problem is is have to attenuate a few clicks to achieve this which softens the attack a bit if you know what i mean. I have been guilty of not straying too much from bass mids and treble at around or just above noon though and i suspect i could get a thicker sound by lowering treble and presence and raising mids and bass. I want a thicker more powerful tone with low to medium gain but i dont want it to be muffled with too little treble and too much bass. I have spoken about attenuators in a band setting before......if i am the only guy using an attenuator i find the sound can lose attack when compared to the others live.

ICBM

I always run these older Marshalls with the bass full up and the mids over halfway, the treble usually just over half and the presence often below half.

Try attenuating just one click, or two, and turn the MV up less far. The trick is usually to get a balance between the two.

shaunm

Hi @billando ;

I use a 78 2104 (covered in a lovely velvet) and I understand what both you and @ICBM are saying. 

I do think that it’s an easy amp to sound thin on the high input however an easy fix for this is to put the bass and mids up full and then the treble almost off. 

The thinner sound on the high input I find helps cut through a two guitar band mix. 

Lately I have been using just the low input and running that all the way up volume wise and the preamp on 3/4. I find that I personally prefer this sound as it is verging on NMV Marshall sounds which I like. I also find the low input is a fatter sound too.

mattdavis

I’ve always got very nice full clean tones on Low input out of my early ‘80s 4104 with master and preamp at about 3-4.  Maybe the broken in 2x12 speakers help. 
I tried maxing the master and then rolling in the preamp but it was quite hissy without much advantage. 
Rediscovering this amp has been a great upside of lockdown. thanks 

bananaman

billando said:

You say the high input has an extra gain stage but couldnt this just be compensated for by keeping the preamp lower if the master is at full? 

Im not sure about my 2104 tbh. Seems like its always thin in my band context unless i use an attenuator to get the master up to at least 5. I have a 4010 with the same speaker (g1265) that seems to have more balls. 

No. A lot of higher gain amps sound quite thin if you keep the gain low. If they were voiced thicker at low gain settings they would be mushy when distorted.  Don't forget the Master Volume was designed with the main goal of being able to replicate the sound of the 4 holers flat out at more sensible volume levels, and the preamp design reflects that. By sensible they still mean bloody loud! And of course it can go as loud as the 4 hole amps. Once power amp distortion kicks in they get really juicy. Your 2104 is the same amp as your 4010, so with 2 speakers instead of one, if anything the 2104 should sound bigger. Try running them both through each others' speakers and see if the problem remains or changes places.

billando

Its a 2144 actually. It has a boost function and reverb. It has more gain than my 4010 no question.

bananaman

Yeah that's a different circuit altogether. A rare amp actually.

hywelg

billando said:

Its a 2144 actually. It has a boost function and reverb. It has more gain than my 4010 no question.

Completely different amp from a JCM800 (2104,2204 etc) I The preamp is entirely different but the power stage is JCM800.

billando

I dusted off an old jcm 800 4212 split channel 50w combo today. Sounds nothing like my 4010 which is pure classic rock acdc all day. Still sounds good though...just different. Whats the thoughts about this amp and also on the boost channel theres a channel volume as well as the master volume....is there a preference for keeping master high and channel volume low or channel high and master lower (for same overall volume) or does it not make a difference?

ICBM

billando said:

I dusted off an old jcm 800 4212 split channel 50w combo today. Sounds nothing like my 4010 which is pure classic rock acdc all day. Still sounds good though...just different. Whats the thoughts about this amp and also on the boost channel theres a channel volume as well as the master volume....is there a preference for keeping master high and channel volume low or channel high and master lower (for same overall volume) or does it not make a difference?

Depends which version of the 4212 it is - there are three, although only the first one is really different. If it's that one there's a big difference in the channel volume and master volume since the MV is post-phase-inverter - the other two both have it before the PI. Whichever it is, just experiment and see which you prefer the sound of - there's no right answer. None of them really sound like a standard MV model though, the circuit is completely different.

There's a quick way to tell if it's the first version - plug the guitar into the FX return. If the master volume controls the level, it's the first. If it doesn't, it's the second or third.

shaunm

@ICBM i used my 2104 tonight. Is there a reason that the high input is considerably louder than the low input or is that just my perception?

JMP220478

shaunm said:

@ICBM i used my 2104 tonight. Is there a reason that the high input is considerably louder than the low input or is that just my perception?

there is an  extra gain stage with  high input ... and in my experience with the head version,  significant vol difference between both inputs

https://robrobinette.com/How_the_Marshall_JCM800_Works.htm#2203_Master_Volume..