Marshall jmp 2104

billando

Does anybody use an attenuator with a jmp 2104 for gigging? And if so what volume do you have it at? We're talking drummer levels non miced. I can get the level to around 4 out of 10 without an attenuator.....will the tone suck of using an attenuator make a nice sounding amp sound not so good?...making it pointless to use an attenuator? 

ICBM

Attenuator ‘tone suck’ is largely a myth, at least if you’re only taking off a few dB - which you will be if you can get it up to 4 without one.

The best one for that amp is probably the Marshall Powerbrake - not available new (why, Marshall?) but not rare second hand.

HHwarner

I use one regularly with my 2204. Master volume up to get the sweet spot (usually just past 1 o clock on mine), Pre amp on about 1 to 2 o clock and attenuator down -3 to - 6 dB depending on venue. Works a treat. I use Marshall Powerbrake btw Instant DC tone lol

billando

Interesting. I find my amp opens up on 5. I actually have a power brake. Would u say that would be a better option than reamping with a power station for taking down the dbs a touch? Not taking cost of attenuators into account.  

ICBM

billando said:

Interesting. I find my amp opens up on 5. I actually have a power brake. Would u say that would be a better option than reamping with a power station for taking down the dbs a touch? Not taking cost of attenuators into account.  

In my opinion, yes. The Powerbrake is simple and works - you don't need anything more complicated.

5-6 is about where they usually go into power stage overdrive assuming the preamp is already overdriving.

billando

Does anyone use these for gigging? I have quite a few amps but always come back to this one. What settings do you use. Without using the attenuator (volume around 4 still not opened up) i find i have to set the preamp to 8 so it adds bass...otherwise the bright cap makes it sound thin in my band mix. With the attenuator i wouldn't go more than a couple of clicks so maybe master up to 6 to get the power valves working and preamp back to 6 or 7.

Do you think the thin open back cab contributes to the thin sound at lower volume?  

HHwarner

As I said, my main gigging rig is a JMP 2204 through a 4x12 ax cab but I have an original 2104 2x12 Combo Case I put it in for band practice. Yes without the attenuator and Master on 4, I have to raise the Pre amp upto around 8 to fatten it up a bit. With the Powerbrake @ -3 to -6 db and master up to 6, pre down to 6 or 7, it really opens up. The open back cab disperses the sound well in the room we play in. I actually prefer it to a closed back in those circumstances.
What speakers are you using btw? If they are G12H 30's they are very efficient @ 100db. Iv got G12-65's in mine. not so efficient @ 97db so the master volume can go up a bit higher (or -3 instead of -6 on PB). They also dont sound as in your face as the G12H. (Iv got a 2045 2x12 cab with G12H in and it takes yer head off)

billando

i have the G12-65s. What you described is exactly same as with me....and also i prefer the power brake to the power station with this amp. The power station makes it too soft in my opinion. How does the 2204 with 1960ax compare to the combo?

HHwarner

The 2204 and 4x12 is superb. I think the G12M is the perfect combination with the 2204 and less efficient again. For gigging Im usually -3 to 0 on the PB and it sounds really fat. Obviously would be pushing your luck in a 2x12 mind. 

ICBM

I don’t own one, but I’ve used a fair few. High input, preamp 8 (Gibson) or 10 (Fender), treble 6, middle 6, bass 10, presence 6 usually. Master 2-6 depending on what you can get away with!

Marshall did fit them with G12M-25s until about 1979, but they are prone to being blown. G12-65s after that, which are totally reliable and also sound better in the combo in my opinion.

For a 4x12”, G12M-25s are fine and sound a bit better than 65s to me - the 4x12” doesn’t need the slight extra bass and smoother treble. (And needs less bass on the amp too.)

p90fool

Definitely run the preamp on 10 and control it with the guitar, it sounds pretty fat then. I was running my 2104 here through the speaker of a 1x12 combo just to test it (plus it's just a crappy phone mic), but at rehearsal volume through its own cab I dial the bass back a fair bit - there's plenty in reserve. 

TTBZ

Love these amps, if I had somewhere I could open it up properly I'd definitely have one!

HHwarner

Another suggestion, try an RFT in V1. They are great Pre amp valves in these amps and really fatten em up

ICBM

HHwarner said:

Another suggestion, try an RFT in V1. They are great Pre amp valves in these amps and really fatten em up

Put RFTs in all the positions if you can - V2 is also very important in any Marshall master volume amp as it's where the preamp overdrive occurs. They're the best for MV Marshalls by a wide margin in my opinion - better than Mullards - and are not that expensive by NOS standards. They also tend to be quite reliable.

billando

I have been experimenting a lot with this amp. I think even if you have the master way up to get power valves cooking it still sounds weak unless you have the preamp at at least 5. I find master at 6 and preamp at 6 is best combination for me.

ICBM

billando said:

I have been experimenting a lot with this amp. I think even if you have the master way up to get power valves cooking it still sounds weak unless you have the preamp at at least 5. I find master at 6 and preamp at 6 is best combination for me.

That's because it's a myth that you need the power valves "cooking". The signature sound of these amps is the cathode-follower tone stack driver overdriving. When the power stage also overdrives - at around 6 on the master with the preamp already distorting - it adds compression rather than much more distortion.

Having the preamp volume too low makes the bright cap on the pot too effective as well. I think that's why I prefer it with the preamp at 10 (no bright cap, effectively) with Fenders and at 8 (a little treble boost) with Gibsons, as much as the difference in gain.

billando

it definitely gets muddier around 6 on the volume mind you i have to attenuate at volumes over 5 so this might explain some of that compression. So do you actually prefer the amp at lower volumes before the power valves clip at roughly 5 on the master?

ICBM

I like it when it just starts to compress, but no higher than that - 5-6 on the master, max. I think they sound great right down to about 2 though, which I know a lot of people don’t.

clarkefan

What's special about these amps having a cathode follower, don't lots of amps use that arrangement?  

I thought those treble peaking 470pf/470k (I think) paths on V1, and both sides of V1 being in series were the 800 sound.

ICBM

clarkefan said:

What's special about these amps having a cathode follower, don't lots of amps use that arrangement?  

A lot do, in the Tweed Bassman/Marshall/Soldano/Dual Rectifier family - but some that you might not expect, eg the AC30 Top Boost. Some Marshalls *don't* have it either, eg the Jubilees.

Personally I think it's critical to the classic rich/ringing Marshall crunch sound, which is one reason I've never thought the Jubilees sound quite 'right', although I know not everyone agrees with that.

It can also cause trouble with some valves, Russian-made 12AX7s don't have adequate cathode-to-filament insulation and often fail at the higher cathode voltage, and I've also come across quite a few JJs.

JMP220478

ICBM said:

Attenuator ‘tone suck’ is largely a myth, at least if you’re only taking off a few dB - which you will be if you can get it up to 4 without one.

The best one for that amp is probably the Marshall Powerbrake - not available new (why, Marshall?) but not rare second hand.

Essential imho - these amps are very conservatively rated at 50w ... :-)