JCM 900 1st go round...

[uraceulose]

Hey guys thanks for everyone's help so far! i really appreciate it.My question is this:

So i just bought a JCM 900. It's my first tube amp...but I am have been been jamming on a dsl 2000 that needed new tubes before i bought this. THe dsl2000 is a 100 watt.... the900 is 50 watt...

Okay so i played at practice tonight and was trying to dial my tones in. i run the 900 througha mesa 4x12 oversized. the 900 has great mids and highs but i was a little bummed on the low end....i guess i was kinda searching for the mesa sound. I didn't want to bring back an old thread by asking about settings... but anything right now will help. i want to keep this amp and I want to learn to utilize it the best i can. any suggestions to thickin things up overall?? pedals?? eq settings?? By the way i have a prs SE tremonti.... stock pups and it was way midy and trebly... i plugged in an 81 les paul and i got a nice tone (for sure) but still missing what i was looking for....

really just want to thicken my over all sound up...a little more chunky... a mix between newer metal and classic rock....

sorry for writing so much probably the jagermeister and blood still pumping from practice!! lol... thanks in advance!!!

 

[thrawn86]

How are your mid's set? The best advice I can give is to crank those mids up. That's a start.

 

[V-man]

1. Marshalls aren't Mesas, and Mesas aren't Marshalls. You want the Brootalz, either works with it's own distinct flavor.

2. Yours will benefit from an EQ pedal, either in the FX loop or before the amp. I have used one and two 10 band MXRs to shape the sound.

3. The amp with the Master past 5 sounds different (and better) than the amp with the master at 3 or below. Yes, the master volume is a great asset when you put the gain up and are playing at bedroom volume, but the amp is made to get loud.

4. Some have benefitted with a BBE sonic maximizer and some despise them. the 382 is $99 new and you can find the enhance models for as much or less used.



My advice: test drive then commit to/buy a good Overdrive to boost your signal (OCD Tube Screamer, Bad Monkey, etc). It adds a third channel (crunch channel when you stomp it on the clean channel). Buy a 10 Band EQ and shape the curve to boost your bass signal (experiment with the FX loop and its sensitivity, as well as placing it before the amp). These two features will give you some sonic options to enhance what you have and shape new tones as well. If this isn't enough, or you have hit a plateau I suggest you grab an attenuator and see what the it sounds like naturally overdriven.

 

[BluesRocker]

1. Marshalls aren't Mesas, and Mesas aren't Marshalls. You want the Brootalz, either works with it's own distinct flavor.

2. Yours will benefit from an EQ pedal, either in the FX loop or before the amp. I have used one and two 10 band MXRs to shape the sound.

3. The amp with the Master past 5 sounds different (and better) than the amp with the master at 3 or below. Yes, the master volume is a great asset when you put the gain up and are playing at bedroom volume, but the amp is made to get loud.

4. Some have benefitted with a BBE sonic maximizer and some despise them. the 382 is $99 new and you can find the enhance models for as much or less used.



My advice: test drive then commit to/buy a good Overdrive to boost your signal (OCD Tube Screamer, Bad Monkey, etc). It adds a third channel (crunch channel when you stomp it on the clean channel). Buy a 10 Band EQ and shape the curve to boost your bass signal (experiment with the FX loop and its sensitivity, as well as placing it before the amp). These two features will give you some sonic options to enhance what you have and shape new tones as well. If this isn't enough, or you have hit a plateau I suggest you grab an attenuator and see what the it sounds like naturally overdriven.

+10000000000000000000000.. Awesome response. My 4500 was lacking bottom end as you say that yours is. Its not JUST your amp. Its the 900's in general. They are tinny sounding compared to others. No you wont get a Mesa sound out of it and never will. But as V-Man said, grab an OD pedal, a Sonic Stomp, and an EQ (I use the GE-7) and CRANK THAT S.O.B!!! Cause it needs to be. Marshalls are built to be pushed, and you can get decent sounds at bedroom levels but great sounds come with a price.. loud.. I like to play loud so I dont use an attenuator.. If you like to play softly then I would recommend an attenuator.

 

[RobS]

+1 more than Bluesrocker.

Check the Bias on it as well, if it's low it will lose bottom end. Not sure what OP valves you have but the original Sovteks can be a bit brittle. I use the JJ6l6gc's and they give lots of bottom end great mids and controlled highs.
And as VMan said, you must turn up the Volume. Sure it will be very loud but then your bass/mid response will greatly improve.
Lots of people dont like the attenuators but I use one at home and it allows you to hear what the amp can really sound like without having your windows blow out. Bias up at about 40ma and you will hear a difference.

Rob

 

[Adrian R]

Most of the previous posts are right on the money..

Before I begin..you mentioned a Boogie cab is being used. ENSURE you have set the impedence correctly on the head! Boogie cabs I have seen are all 8ohm cabinets..make sure you have the head set correctly or you'll fry it in no time..(ABSOLUTE MUST)

900s are really misunderstood amps..and to a degree, from revelations that have more recently been discovered, by Marshall themselves!! They can produce some of the best guitar tones ever created if you learn how to make them sing.

The 900 series are amps that were designed to be driven hard, and to be used effectively with outboard gear i.e. EQs, OD pedals, etc..and this is why they are all appear to be overbiased right from Marshall themselves..

To start with; I'm nearly positive that the amp your 900 is probably running way overbiased...meaning cold and thin sounding. If you don't have the ability to check this I suggest you learn (which is easy and with minimal expense) or take it to a good tech whom you trust and explain to him what the problem is, mention the word OVERBIASED.... That amps needs to be biased warm/hot..like 35-40mA..

If the amp has EL34s in it I am (almost) POSITIVE it is running overbiased. A tech will be able to make the adjustments in the bias circuit (modification) to allow them cold ass 34s to run hotter giving the amp much better warmth and bottom end, not to mention more volume and punch. And easier fix is just to get yourself a good set of either JJ6L6GCs or SED 6L6GCs (winged=C=) and install them. You may even be able to get away without checking the bias and making adjustments, but you should check it and set it if nessecery to ensure achieving the amp's maximum tone potential.

If the amp has 5881 tubes in it replace them with 6L6GCs as well. They sound better PERIOD. (bigger, punchier, more open, less compressed)

6L6s sound better imo anyway..cleaner, tighter, WAY better bottom end..and much better suited to hard rock/metal tones.

The tube/bias point can simply NOT BE OVERSTATED...you really need to start with this first.

After this you can begin experimenting with OD pedals up front to drive the preamp harder. Again this amp was designed to be used in this manner. Ibanez tube screamers work well, Maxon OD pedals work even better, and clean boosts work wonders too. i.e. BBE Boost, Seymour Duncan p/u boost, MXR Micro amp, Modtone clean boost..etc..

After that the real shit stopper is running either a MXR-108 in the FX loop, or even better (imo) is a BBE 362 Sonic Maximizer NOT THE SONIC STOMP BOX!!!!!!..I've tried the sonic box both up front and in the loop and the rack mounted 362 BLOWS IT AWAY... I cannot stress enough how much the utilization of either one of these above mentioned units will enhance the overal sonic quality of that head. The difference with it and without is totally night and day.


Finally, if you are really looking for that coveted 'Marshall voice' (something we all here understand) try plugging in either a good quality Gibson or Fender Strat/Tele..I am quite certain at this point you will achieve that sound you are wanting th hear...that sound in your head that drives us all fucking insane..

Don't give up on that 900 man...if you follow this simple guide you will be rewarded with incredible Marshall bliss..something that the frickin' Boogie can only 'try' to recreate.

 

[jcmjmp]

Bias the amp properly as Adrian R has stated. Good tubes make a difference. Ting Sol 5881s or SED =C= El34s are both excellent choices.
Put some tung sol 12AX7s in the preamp section.

Then.... you have to mod the amp for a variable resonance control. It is a very simple mod that will bring out the amp's bass response and a competent tech should be able to do it.

 

[jcmjmp]

To start with; I'm nearly positive that the amp your 900 is probably running way overbiased...meaning cold and thin sounding. If you don't have the ability to check this I suggest you learn (which is easy and with minimal expense) or take it to a good tech whom you trust and explain to him what the problem is, mention the word OVERBIASED.... That amps needs to be biased warm/hot..like 35-40mA..

Cold and thin sounding is usually associated with underbiasing an amp, i.e. not enough current. Is that what you meant?

 

[Adrian R]

Cold and thin sounding is usually associated with underbiasing an amp, i.e. not enough current. Is that what you meant?

**Dude..

Nope, I was correct, that is running too much negative voltage to the tube's grid attenuating the amount of actual current running though the valve section of the amp..(overbiasing..too much correction).

A good analogy would be that of NASCAR'S Sprint Cup series(f'-ed/up) policy of mandating the usage of restrictor plates on top of the engine's intake manifold...therefore minimizing the amount of air/fuel mixture...thus less HP.

Oh and btw DO NOT USE TUNG-SOL 5881 TUBES!! The 900s high plate voltage will fry em' in no time. The only 5881 that will work is Sovtek's 5881WXT..which basically is a 6L6 ANYWAY..and can operate as high as 30w..I know and I have tried them...Tube-Depot.com was very nice in allowing me to return them!

Ahh..approaching noon..NFL and almost time for a Bitburger beer.....

 

[Hollowbody]

Cold and thin sounding is usually associated with underbiasing an amp, i.e. not enough current. Is that what you meant?

That's Ohms law, right? Voltage vs. current.

I GOT IT!!



Just kidding.

...sorta

...eh, sorry

 

[jcmjmp]

**Dude..

Nope, I was correct, that is running too much negative voltage to the tube's grid attenuating the amount of actual current running though the valve section of the amp..(overbiasing..too much correction).

Hmmm... ok, but you seem to be using contradicting terms. If you mean too much negative voltage at the grid, then I agree.

Oh and btw DO NOT USE TUNG-SOL 5881 TUBES!! The 900s high plate voltage will fry em' in no time. The only 5881 that will work is Sovtek's 5881WXT..which basically is a 6L6 ANYWAY..and can operate as high as 30w..I know and I have tried them...Tube-Depot.com was very nice in allowing me to return them!

Ahh..approaching noon..NFL and almost time for a Bitburger beer.....

Where did this info come from, that the TS 5881 can't handle high voltages? The plate voltage is approx 470vdc in a JCM900?

 

[Hollowbody]

My bad timing.

...and just observing

 

[Cardiac Tom]

The 900 can be fickle, but you will get there...

It took me years to get what I want from it, and I am still working on it...But I am very happy with mine currently...Just keep plugging away...And take the advice of what the others have said...I know I'm going to...I learned so much hanging out here the last few days...

The other guitarist in one of my bands uses a Triple Rec with a Vader cab and our sounds blend nicely...Personally, I don't like the Mesa Triple Rec...Tons of people in death metal have them so everyone sounds too similar...I like being the oddball...lol

 

[Adrian R]

Hmmm... ok, but you seem to be using contradicting terms. If you mean too much negative voltage at the grid, then I agree.

No, and I respectfully disagree. I am not contradicting myself. Overbias=OVER-CORRECTION..as stated earlier applying too much NEGATIVE voltage to the grid minimizing the amount of current PASSING through the grid..(and amp) thus sounding cold and thin..JUST LIKE a carburator in where the fuel/air mixture is too lean..Underbiasing would be exactly the opposite in where tubes run too hot, or rich if you will..minimizing headroom, increasing overall circuit noise..and minimal tube life.



Where did this info come from, that the TS 5881 can't handle high voltages? The plate voltage is approx 470vdc in a JCM900?

Again, I will reiterate (respectfully of course)I tried them out in one of my 4500s and it torched em' in where I needed them biased. (35-40mA) They are rated specifically at 25w max..in where the 6l6GC can achieve 30w max..in where you will approach that threshold in warmer bias settings. Bob at Eurotubes warned me of this first as well..and I didn't heed his advice (dumb ass me)fortunately the vendor allowed me to return the tubes. Additonally, I have seen 900s PVs exceed 480vdc.

 

[jcmjmp]

No, and I respectfully disagree. I am not contradicting myself. Overbias=OVER-CORRECTION..as stated earlier applying too much NEGATIVE voltage to the grid minimizing the amount of current PASSING through the grid..(and amp) thus sounding cold and thin..JUST LIKE a carburator in where the fuel/air mixture is too lean..Underbiasing would be exactly the opposite in where tubes run too hot, or rich if you will..minimizing headroom, increasing overall circuit noise..and minimal tube life.

Again, I will reiterate (respectfully of course)I tried them out in one of my 4500s and it torched em' in where I needed them biased. (35-40mA) They are rated specifically at 25w max..in where the 6l6GC can achieve 30w max..in where you will approach that threshold in warmer bias settings. Bob at Eurotubes warned me of this first as well..and I didn't heed his advice (dumb ass me)fortunately the vendor allowed me to return the tubes. Additonally, I have seen 900s PVs exceed 480vdc.

Cool - All I said was contradicting terms and I never said you contradicted yourself. To me, overbiasing means too little negative voltage and as usual, I'm probably the only one that thinks this way. Your logic is sound and I'm not saying you're wrong, I just got confused when I read your post, that's all Overbiasing, to me, in the context of a Class AB amp means too much current flowing, not too little. Overbiasing, again, from my experience is when your make the class AB crossover notch dissappear and continue to reduce grid voltage.

I didn't know that the TS 5881 was no good in the JCM900s. Thanks for the tip.

 

[uraceulose]

HELL YEUAHH!!! This forum rocks!!! u guys are the shit. Thanks so much for ur guys' help. I will start with the tubes. I know before I bought this amp the amp was serviced and pots were changed and "the front end" was re done(?)... I am not sure if they put in new tubes. It doesn't sound like old tubes...but biasing may be the factor. I will start there... anyone know how much (roughly) a bias adjustment might run me?? I don't want to go to the music store and just get whacked on service costs.

Oh and by the way... don't worry when I am talking about tones and my amp generally the only way i jam is with the volume cranked. No bedroom volumes here!!! Thanks guys!!!

 

[Adrian R]

HELL YEUAHH!!! This forum rocks!!! u guys are the shit. Thanks so much for ur guys' help. I will start with the tubes. I know before I bought this amp the amp was serviced and pots were changed and "the front end" was re done(?)... I am not sure if they put in new tubes. It doesn't sound like old tubes...but biasing may be the factor. I will start there... anyone know how much (roughly) a bias adjustment might run me?? I don't want to go to the music store and just get whacked on service costs.

Oh and by the way... don't worry when I am talking about tones and my amp generally the only way i jam is with the volume cranked. No bedroom volumes here!!! Thanks guys!!!

Dude..

You are welcome! Strongly suggest you go to or call Bob at Eurotubes.com. He will get you setup correctly. Forget taking it to a music store..they'll most likely not only overcharge you, but will not steer you in the right direction as most don't understand 900 series Marshalls. You can install the new tubes and bias it yourself (JJ 6L6GCs are the ones to get for that specific amp; TRUST ME I have tried them all..SEDs are good too). He has online videos showing you how to do it..or you can email him or call him and he will personally assist you with the process. Its WELL WORTH the investment of time and money (which is not much)and in the process, learn something about tube amps which in turn will help you dial in your own personal tone.

BTW..the 'front end' of the amp is pre-preamp if you will. That is boosting the guitar's signal before the guitar's signal enters the amp through the amp's guitar input jack. This is where you are going to want to use some kind of overdrive or clean boost pedal. This alone will have a HUGE impact on your tone.

I hear ya about VOLUME bro..900s, like 800s, sound best when cranked. Keep frickin' rockin' man!

 

[Adwex]

I had a 4500. It was useless without an EQ in the loop, with the lows boosted.

 

[Adrian R]

I had a 4500. It was useless without an EQ in the loop, with the lows boosted.

**Yes, the amp does sound better with an eq or similar device in the loop, but I wouldn't say usless, thats pretty strong eh? Your a moderator, and I have to assume you have followed this thread and others of similar pedigree so I find this remark a suprise. Of course if you haven't followed this thread, and again; others of its nature, I suggest you do. There is a plethora of information leading to tons of misinformation about this very head you are commenting on.

Adding an eq to the loop is one of many things, but not nessecerily the most important thing to getting killer tones from this amp. Chances are very strong that the 4500 you did experience was most likely ill in one of the many catagories clearly illustrated by this thread and others like them.

900s can kick serious budda if intelligently approached.

 

[Adwex]

**Yes, the amp does sound better with an eq or similar device in the loop, but I wouldn't say usless, thats pretty strong eh? Your a moderator, and I have to assume you have followed this thread and others of similar pedigree so I find this remark a suprise. Of course if you haven't followed this thread, and again; others of its nature, I suggest you do. There is a plethora of information leading to tons of misinformation about this very head you are commenting on.

Adding an eq to the loop is one of many things, but not nessecerily the most important thing to getting killer tones from this amp. Chances are very strong that the 4500 you did experience was most likely ill in one of the many catagories clearly illustrated by this thread and others like them.

900s can kick serious budda if intelligently approached.

Let me rephrase then....my...I repeat..."MY" 4500 was seriously lacking in low end. I found that boosting the lows with an EQ in the loop was the only way I would be satisfied with it, so, without the EQ, I didn't want to use it.

I played a 4100 once that also needed some help with the bass.

Yes, I followed this thread, and other similar ones. I'm not the only one who remarked that the 4500 lacks low end, it's a widely held opinion. I don't believe it's a coincidence that the OP is having the same issue.

Btw, I fail to see how using an EQ to boost certain frequencies to enhance an amplifier's tone can be contrued as unintelligent.