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Marshall JMP-1 Preamp Tubes


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I pulled out the stock Marshall tubes last night and put in some

Electro Harmonix 12AX7's.

 

OH my....

 

Not sure if those stock tubes were just old or if they really sounded inherently bad, either way it sounds amazing now.

 

Anyone who says the tubes aren't doing anything in the JMP-1 is full of crap. If the tubes really weren't doing anything I suspect changing them wouldn't make much of a difference.

 

Looking at the JMP-1 schematic: there IS a diode clipper in there, but it doesn't even start clipping until the signal at that point hits about 2.1V (about 3 diode drops). The tube is doing the magic up until then.

 

Anyway, I digress....

 

These new tubes made a huge difference in the tone of the preamp. What was once somewhat harsh sounding distortion is now super-smooth, and more focused.

 

I had to tweek the EQ a bit since the new tubes affected the high-

end, but I'm much happier with the overall sound of it now.

 

I'm buying some JJ's tubes tonight after work. I'll try them out

this weekend as well. I've heard good things about JJ's in the JMP-1.

 

Jason

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Originally posted by stilwel


Anyone who says the tubes aren't doing anything in the JMP-1 is full of crap. If the tubes really weren't doing anything I suspect changing them wouldn't make much of a difference.


Looking at the JMP-1 schematic: there IS a diode clipper in there, but it doesn't even start clipping until the signal at that point hits about 2.1V (about 3 diode drops). The tube is doing the magic up until then.


 

Gee why do you need a SS clipper at all?? I mean I could understand having a boost switch that engages clippng diodes more dirt for tones that require more than the 4 gain stages provided by 2 dual triodes(which btw is quite a bit of gain)But theses diodes are voltage dependant and always in the circuit!Plus the tubes I'm pretty sure are used in parallel not series.The JMP-1 is pretty much a Valvestate preamp.

 

 

It SUX:)

 

 

 

 

 

 

Yo Billy wassup?:)

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The tube stages are in series. One tube is used for the OD channels, the other tube is for the clean channels.

 

 

This has been discussed to death, so I won't comment on it anymore.

 

 

I have the JJ tubes in hand. I'll try them out sometime this weekend and give full report of EH vs JJ 12AX7's.

 

jason

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Hey stilwel,

 

Thanks for the info! Definitely let us know how you like the JJ's versus the EH's. Some time ago I read where one guy had tried a JJ ECC83 in V1 socket and a JAN GE12AX7 in V2 socket, and that sounded really good. I've been meaning to give that combo a try some time.

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Originally posted by stilwel

The tube stages are in series. One tube is used for the OD channels, the other tube is for the clean channels.



This has been discussed to death, so I won't comment on it anymore.



I have the JJ tubes in hand. I'll try them out sometime this weekend and give full report of EH vs JJ 12AX7's.


jason

 

By your description thats PARALLEL operation and is exactly also how I was informed of thier function so it was correct.

 

LOL! If you are going to contribute to a forum in a credible fashion it helps to know the difference.:rolleyes:

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Originally posted by Soldano67



By your description thats PARALLEL operation and is exactly also how I was informed of thier function so it was correct.


LOL! If you are going to contribute to a forum in a credible fashion it helps to know the difference.
:rolleyes:

 

Laugh all you want....but where is YOUR Electrical Engineering degree from??

 

Mine is from Purdue University.

 

By MY description I said that one tube was dedicated to each channel. Each tube has 2 stages. These 2 stages are run in series. If you can read a schematic it's very clear they are not run in parallel.

 

Anyway this thread was about how much a tube change influenced the tone of the preamp, dramatically in this case.

 

out

jason

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Originally posted by stilwel



Laugh all you want....but where is YOUR Electrical Engineering degree from??


Mine is from Purdue University.


By MY description I said that one tube was dedicated to each channel. Each tube has 2 stages. These 2 stages are run in series. If you can read a schematic it's very clear they are not run in parallel.


Anyway this thread was about how much a tube change influenced the tone of the preamp, dramatically in this case.


out

jason

 

Your description was basic and describes the use of the tubes as being parallel -ie, each tube works independantly for clean and dirty.Thats all that is required.

 

Tubes is the subject NOT the individual triodes.

 

Jason, life is too short to be a wanker especialy a pretentious one so quit while your ahead.

 

Stupid troll :rolleyes:

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Originally posted by Soldano67



Your description was basic and describes the use of the tubes as being parallel -ie, each tube works independantly for clean and dirty.Thats all that is required.


Tubes is the subject NOT the individual triodes.


Jason, life is too short to be a wanker especialy a pretentious one so quit while your ahead.


Stupid troll
:rolleyes:

 

...I'm the troll???

 

If you look at the top of the page, I started this friggin' thread.

 

You've successfully hijacked it off-topic.....well done.

 

 

.... enough of this nonsense. I have tubes to try out in my JMP-1.

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Originally posted by stilwel



...I'm the troll???


If you look at the top of the page, I started this friggin' thread.


You've successfully hijacked it off-topic.....well done.



.... enough of this nonsense. I have tubes to try out in my JMP-1.

 

 

Ya the sad part is you became a troll in your own post lol

 

Off topic? mm not very far off since you and I have established once and for all that the JMP-1 uses its 2 tubes in a parallel configuration.It means that all the distrortion the preamp generates after a mild overdrive(1 tube) is all diode clipping, this is very significant.It means that the tube has very little effect on tone regardless of the quality of the tube.

 

This also means the JMP-1 is a Valvestate design and my accusation that Jimmy at Marshall has been misleading consumers for over decade that its a tube preamp has been validated-again.You cannot get decent overdriven Marshall sounds from one tube its impossible.It should've been a "budget"

piece of gear not the $1000 compete with a Tri Axis "pro" gear preamp.

 

Jim Marshall you are a huckster asshole.I mean the way you duped my good friend Billy Corgan is unforgivable:mad: :)

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Originally posted by stilwel

The tube stages are in series. One tube is used for the OD channels, the other tube is for the clean channels.

 

 

aha. I've been meaning to ask about this for some time as I will definately be changing my tubes eventually. So which one is for which channel?

 

and i can't wait to hear about the tubes :

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Hey Soldano why are you so anti JMP-1?

 

If you don't like it then that's fair enough, but you should try to make sure it doesn't take over your life.( don't take it so personal, calling people names isn't big or clever. )

 

We'd all like nice expensive boutique preamps but can't all afford it. At the end of the day if you own one of these( like thousands of others) and you like it then that's all that matters.

 

I'm not that technically minded but if the valves do nothing what are they in there for, and why does changing them make a difference to the sound.

 

I'd like a Triaxis but over here in the UK they are nearly four times the cost of the JMP. Are they four times better ? Perhaps they are.

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Originally posted by sp_spaceboy

 

aha. I've been meaning to ask about this for some time as I will definately be changing my tubes eventually. So which one is for which channel?

 

and i can't wait to hear about the tubes :

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Originally posted by Driftone

Hey Soldano why are you so anti JMP-1?


If you don't like it then that's fair enough, but you should try to make sure it doesn't take over your life.( don't take it so personal, calling people names isn't big or clever. )


We'd all like nice expensive boutique preamps but can't all afford it. At the end of the day if you own one of these( like thousands of others) and you like it then that's all that matters.


I'm not that technically minded but if the valves do nothing what are they in there for, and why does changing them make a difference to the sound.


I'd like a Triaxis but over here in the UK they are nearly four times the cost of the JMP. Are they four times better ? Perhaps they are.

 

 

Hey Drift I understand your point but just keep in mind stilwel says he is an electrical engineer as a way to add credibiltiy to his point even though he knew he was wrong about a pretty basic concept-then tries to say "well what I really meant was.....". He opened himself up for a lil abuse;)

 

You have to remember that in America the Mesa Boogie Tri-Axis is about 1500 full retail(people paid less too)The JMP-1 was $1000 new.The Mesa is a 100% tube preamp that uses multiple(5) tubes in a series configuration to get overdrive,just like a regular amp preamp would.Its signal path is 100% tube and uses no SS to assist in clipping or buffering.

 

The JMP-1 Well I've already covered it,Its a hybrid which owes most of its tone to the chips and diodes it has.Marshall calls it a "tube preamp" which while accurate doesnt tell the true story its a half truth-used cars salesman truth.

 

The JMP-1 sounds and responds like a refined distortion pedal.The Mesa responds like a tube amp, very organic.

 

The JMP-1 is worth to me $500 new which I think it is in the UK 500 pounds.

 

Not only is it a poor concept it failed in execution Jim makes it worse by "making a pitch" and charging way more than its worth.He burned alot of suckers.

 

All other "tube" midi preamps use the tubes in series to generate distortion (with the exception of the rocktron Pirhana, its like the JMP-1 and sounds like trash too) and generate a "genuine" sound.

 

Jim has never made a worthy tube preamp ever.His first-the 9000- had 3 tubes and was all tube but it was a bit wierd and the lead channel while having alot of gain was voiced oddly.subsequently thta preamp gets mentioned by no one and people have to give them away on eBay.Then he makes a Hybrid midi preamp(JMP-1) and while it has great feaures and lay out the sound and feel really bites.

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Mine responds like a tube amp when my power amp is cranked on stage. It sounds so much better than my friend's modded JCM 800 and it's 10000000 times more versatile. I don't care if it's "all tube" or not. I like it and people compliment my tone. Marshall must've done something right to have so many famous people using the unit.

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Originally posted by stilwel



V1 is for the clean channels


V2 is for the OD channels


I put the EH tubes in both channels. The EH tubes darkened everything up a bit. So I may search for a brighter tube to put in the clean channel, but so far I like the EH in the OD channels. It would be cool to have 2 different tubes in there that accentuate the qualities of both channels. Who knows, I may end up putting the stock marshall ECC83 back in for the clean channel???


jason

 

 

hmmm. well, I definately expected it to darken it a little, cos the stock tubes often seem a little harsh in the midrange. The highs always sound kinda fuzzy aswell - bit without my 20/20 I'm still running it through an ancient FAL Kestrel solid state amp that a friend of a friend found on a skip... so any tonal traits can't really be trusted at this stage...

 

but would you say that the new tubes have improved what I mentioned above? It'll be interesting with the JJs too, cos a lot of people complain that their preamp tubes are too dark...

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Originally posted by sp_spaceboy



hmmm. well, I definately expected it to darken it a little, cos the stock tubes often seem a little harsh in the midrange. The highs always sound kinda fuzzy aswell - bit without my 20/20 I'm still running it through an ancient FAL Kestrel solid state amp that a friend of a friend found on a skip... so any tonal traits can't really be trusted at this stage...


but would you say that the new tubes have improved what I mentioned above? It'll be interesting with the JJs too, cos a lot of people complain that their preamp tubes are too dark...

 

 

I would say that the new EH tubes were definitely an improvement. The high-mid fuzz is gone. Very smooth sounding now.

 

I'm actually running my JMP-1 through a Marshall VS8008 solid-state power amp. I just don't trust a tube power amp in a live setting. I've seen too many bands lose a guitar player mid-song. That and I like to be able to carry my rack with one hand, not 2 people. I'm sure the Mesa 20/20 and the Marshall EL34 amps sound fantastic, but i can't justify that expense, or the weight when my rig sounds great as it is.

 

jason

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Hey Drift I understand your point but just keep in mind stilwel says he is an electrical engineer as a way to add credibiltiy to his point even though he knew he was wrong about a pretty basic concept-then tries to say "well what I really meant was.....". He opened himself up for a lil abuse;)

 

 

I'm not saying I was wrong. Running tubes in parallel would imply they are both at least in the same circuit and being driven at the same time. But as I said before one tube is in the OD channel, the other is in the clean channel. That's hardly in parallel. Putting your speakers in parallel doesn't mean you're only using one at a time does it?

 

Each tube has 2 stages to it. The way the tubes are used in the JMP-1 circuit places these 2 stages in series with one another. There is nothing parallel about it at all.

 

jason

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Originally posted by BillyCorgan

Mine responds like a tube amp when my power amp is cranked on stage. It sounds so much better than my friend's modded JCM 800 and it's 10000000 times more versatile. I don't care if it's "all tube" or not. I like it and people compliment my tone. Marshall must've done something right to have so many famous people using the unit.

 

What famous people? No artist that demands an aggressive rock/metal tone uses one. Even your god BC uses a Diezel now.

 

The only rock figure using them was Stephen C from the Dedtones and it was fine for the simple chunk crap that comprises thier music.But he uses KranK amps now

 

:)

 

BTW people use to compliment me on my Peavey Bravo's tone lol

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Originally posted by Soldano67



What famous people? No artist that demands an aggressive rock/metal tone uses one. Even your god BC uses a Diezel now.


The only rock figure using them was Stephen C from the Dedtones and it was fine for the simple chunk crap that comprises thier music.But he uses KranK amps now


:)

BTW people use to compliment me on my Peavey Bravo's tone lol

 

Deftones

Billy and James from the Pumpkins

All 3 guys in Iron Maiden

Billy Gibbons

Kirk Hammet

Jerry Horton from Papa Roach

 

John 5 of Marilyn Manson has this to say about the JMP-1 in the latest issue of Marshall Law:

"If there's a professional musician out there that has the money, go out and get the EL34 100/100 and the JMP-1 because it WILL change everything. It will change the way a player plays because they sound so good. I wish I could go back in time and use those on all my sessions!"

 

...and this is a guy who has done 100's of sessions for pop, rock, metal and country artists.

 

If it's good enough for them.....

 

And you can't use the argument that they don't use them anymore. You and I both know that guitar players tastes change. Especially Krank, those guys are just looking for a way into the market so they are giving them away to anyone who will play them.

 

Jason

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Originally posted by stilwel



Each tube has 2 stages to it. The way the tubes are used in the JMP-1 circuit places these 2 stages in series with one another. There is nothing parallel about it at all.


jason

 

 

AGAIN THIS WAS NEVER THE POINT OR THE ARGUMENT AIRHEAD

 

The 12 ax7 has already been identified as a dual triode at least 3 times in this thread why the fuck do you bother saying it over and over and over and over and over?? nobody missed the point you said later that the single tubes run their triodes in series which wasnt relevant to the point in the first place jeezuz stfu!:rolleyes:

 

Are you on fucking drugz? I wasnt talking about the single tubes function dipshit I've made that quite clear.

 

THE TUBES DO NOT CASCADE IN SERIES IN RELATION TO EACH OTHER YOU DUMB STOOPID MUTHERFUCKER

 

THEY RUN INDEPENDANTLY PARALLEL TO EACH OTHER IN THE CIRCUIT.

 

 

Honestly you might be a ee but your reading comprehension leaves alot to be desired.

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Originally posted by stilwel



I'm not saying I was wrong. Running tubes in parallel would imply they are both at least in the same circuit and being driven at the same time. But as I said before one tube is in the OD channel, the other is in the clean channel. That's hardly in parallel. Putting your speakers in parallel doesn't mean you're only using one at a time does it?

jason

 

 

You dont have to say your wrong I did and you are.

 

we already well understand what tubes are alloted to what channel its not a point of contention and it certainly isnt helping your argument or helping you see the point.

 

What you keep missing is the fact amps dont have thier tubes configured the way the JMP-1 does in order for a dedicated preamp to act like a preamp in an amp the tubes must cascade into each other in a series fashion or you cant attain smooth all tube clipping.This is the most important point of distinction for a product claiming to be a tube preamp.

 

Sure the word parallel could be used in 2 ways here but I've already explained which meaning that is relative to the discussion.

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Originally posted by stilwel



Deftones

Billy and James from the Pumpkins

All 3 guys in Iron Maiden

Billy Gibbons

Kirk Hammet

Jerry Horton from Papa Roach


 

 

Deftones sound sux

 

Splashing Dumpkins sound sux

 

Live Iron maiden tones sux

 

Billy Gibbons best tones dont use the JMP-1 its only used for the modern processed sounds which suck

 

99.99% of Kirks Tones are Mesa,Marshall,ADA MP-1w/tube screamer

 

PaPA Roach sux I mean who? where are they now??

 

Only 3 bands on your list qualify as true(stage and studio) users of the JMP-1 and thier sound sux: Deftones,Papa Roach,Splashing Dumpkins.

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Originally posted by BillyCorgan

The guy from Fear Factory uses one now. Tell me that's not aggressive.
:p

 

Billy you know only Dino's stolen/destroyed modified JCM 800 was the only amp that had the most crushing tone.

 

comedy relief I suppose eh?;)

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