JCM900 modifications?

[Axl H]

Hey.

For a 1990's JCM900 4501 Dual reverb, what mods are good for ataining more gain?

And perhaps getting a more JCM800/SLP like sound.

And just plain simple, which mods are good to give it a more metal sound like metallica?

Thanks.

-AH.

 

[V!N]

Re: JCM900 modifications?

Congratulations, rarely (if ever) have I seen so many contradictions in one single post.

 

[Vasshu the humanoid typhoon]

Re: JCM900 modifications?

Yeah had me stumped as well
Get a better amp maybe??

 

[greendy123]

Re: JCM900 modifications?

Well, the easiest mod would be tryout different high gain pre-amp tubes to fine one that will give the distortion your looking for. There are many combinations of tubes you can and also position effects the tone too. If that does not work you send your amp out to be modified.

 

[Liquid]

Re: JCM900 modifications?

:smack:

 

[Axl H]

Re: JCM900 modifications?

HAHA lol sorry it was like night in DK at that time.

What I mean is having it modified to get more gain out of it, and getting that kinda like more 80's metal (Twisted Sister, Metallica, etc) sound instead of the under-gain **** it has now.

What valves and such are good for that?

And no, I cant afford a new amp

 

[Kamanda~SD]

Re: JCM900 modifications?

Um...well in 80's metal the jcm800 was popular and usually modded...and a jcm900 is basically a modded jcm800.

I suggest trying new tubes, lookup mods on the net and also fool around with your settings like crazy and don't forget to crank it.

 

[Axl H]

Re: JCM900 modifications?

Hmm, if I sold my JCM900 and collected a bit dough, i would probs have like 650usdm what amps and such used as new would be good for getting Mostly Metallica (Kill em all to black album), a bit of Twisted sister and a little bit AC/DC?

Tops aswell as combos.

Thanks.

 

[Kamanda~SD]

Re: JCM900 modifications?

Hmm, if I sold my JCM900 and collected a bit dough, i would probs have like 650usdm what amps and such used as new would be good for getting Mostly Metallica (Kill em all to black album), a bit of Twisted sister and a little bit AC/DC?

Tops aswell as combos.

Thanks.

If someone asked for that I would actually reccomend a 900! Or a 800 with an OD pedal for the more high gain stuff (excluding the price BTW).

 

[Axl H]

Re: JCM900 modifications?

Hmm okay, but what mods can be done to give it a bit more kick or so to say in its sound?

perhaps a new speaker?

Theresa G12T AFAIK in it now.

What tubes are good for more gain and such?

 

[greendy123]

Re: JCM900 modifications?

Checkout the vault it has a high gain pre-amp tube shootout there. If you plan to look at selling the amp and getting another one I would suggest the JCM900 master volume series. In the earlier production they sold them with el-34s, definitely need them for AC/DC tones, then there are 2 types. The slx and non versions, slx is basically the non-version with one more preamp, and the non-version is has less gain as a result of 3 preamps compared to the 4 preamps of the slx version. Those amps can sell for around the price you are looking for, but el-34 version come up every few days to weeks, so they may be hard to find.

 

[Axl H]

Re: JCM900 modifications?

Hmm just checked, those Sovtek 12AX7LPS are very cheap here, should i just get 3 of them?

Should the Power-Tubes be changed? Theyre 5881's.

And will the 12AX7 go in smoothly without any mods so ever?

And are the tubes difficult to change?

Thanks for the help.

 

[Sune]

Re: JCM900 modifications?

Checkout the vault it has a high gain pre-amp tube shootout there. If you plan to look at selling the amp and getting another one I would suggest the JCM900 master volume series. In the earlier production they sold them with el-34s, definitely need them for AC/DC tones, then there are 2 types. The slx and non versions, slx is basically the non-version with one more preamp, and the non-version is has less gain as a result of 3 preamps compared to the 4 preamps of the slx version. Those amps can sell for around the price you are looking for, but el-34 version come up every few days to weeks, so they may be hard to find.

Indeed, you can get them around here if you're lucky (I have a 50 watt version as you see in my signature)

I found and bought mine on the german ebay site, and got it shipped to me relatively cheap and fast. So AH^DK, if you need sites to look at used amps on, try the german ebay site, of course not all the sellers ship to other countries, but many do, you can talk to them...Check the site regularly and I'm sure you'll find something you'd like.

 

[greendy123]

Re: JCM900 modifications?

Hmm just checked, those Sovtek 12AX7LPS are very cheap here, should i just get 3 of them?

Should the Power-Tubes be changed? Theyre 5881's.

And will the 12AX7 go in smoothly without any mods so ever?

And are the tubes difficult to change?

Thanks for the help.

The tubes are 5881's, so thats holding you back on the AC/DC tone, the tone is from using el-34 power tubes. The power tubes can be changed but your amp need to be modded to el-34's. I don't how it would sound if you changed them, but it would definitely sound closer to main Marshall tone.

 

[Kamanda~SD]

Re: JCM900 modifications?

To use El34;s you would have to rebias it and it would DEFINATLY get you that "marshall" sound! Also if your going to sell it a used jcm2000 might be in order.

 

[Axl H]

Re: JCM900 modifications?

How much does it usually cost to get it rebiased and which EL34's are good?

And is that also alot of the way to get the sound of TS and Metallica?

And what else needs to be modified?

 

[thucydides]

Re: JCM900 modifications?

How much does it usually cost to get it rebiased and which EL34's are good?

And is that also alot of the way to get the sound of TS and Metallica?

And what else needs to be modified?

I think my labor charge was around 25-30 dollars (US). Four EL 34s were around $60, and preamp tubes were about $60.

A previous post suggests the Marshall 2000 series. A DSL would be a great idea if you sold the 900.

 

[Axl H]

Re: JCM900 modifications?

Theyre too expensive here.

The poweramp tubes, would the EL34 be best for the Rectifier like sound?

And what mods is it that needs to be performed?

 

[Axl H]

Re: JCM900 modifications?

Theyre too expensive here.

The poweramp tubes, would the EL34 be best for the Rectifier like sound?

And what mods is it that needs to be performed?

Bumpage.

And are EHX or Groove Tubes the best EL34's?

The Mullards are quite expensive..

 

[Axl H]

Re: JCM900 modifications?

Just looked, withoutover the tubes, i need a drive pedal for giving the extra. gain.

Must be good quality and have a good sound to give me that extra kick for MoP, RTL and all.

I have been looking at:
Ibanez TS-9/808.
Fulltone Fulldrive 2.
CM Plexitone.
CM Heavy Drive.
Boss SD-1/OD3.
Vox Britboost.
Reezafratzitz.
Marshall Jackhammer (Which i already have, dont have it home though, but how good is it for boosting up to tallica levels?)
I know its a lot different but i was kinda thinking like.


My setup would be
Crybaby (Have it)..
MT-2 just for some fun (have it).
DOD FX86B (have it).
Any of the pedals.
Behringer Chorus UC100.
Behringer EQ.

Or going for a setup with
Three pedals, a chorus and a eq and a boost/drive pedal.

I have about 425USD for those three, or get a Korg AX3000G or Boss GT-8.