right so basically what i need to know is

[DannyDowd]

what tubes i should replace my 6L6's with in my jcm 900, the combination of the jcm 900 and my gibson sg doesnt have enough warmth for my liking, ive heard a lot about el34's, any specific model or brand of them that people feel would add a bit more meat/lows and a nicer tone than the harsh bite i currently have. ( i dont want to have to buy a new head, there must be a cheaper but effective alternative :\ ... )

Thanks a lot.

[BigB]

what tubes i should replace my 6L6's with in my jcm 900

Your amp is supposedly running on 5881, not 6L6 (=> which really means 6L6CG nowadays), but anyway:

the combination of the jcm 900 and my gibson sg doesnt have enough warmth for my liking, ive heard a lot about el34's,

You'll need quite a few mods to run a 5881 JCM900 on EL34's. If you're willing _and able_ to do these mods by yourself well why not, but even then it's not going to make such a difference, and possibly not in the direction you'd expect. I did own an early EL34 JCM900, had a few occasions to compare it with some later 5881 models, the difference was very subtle at best, and mostly the 5881 versions sounded warmer to me.

any specific model or brand of them that people feel would add a bit more meat/lows and a nicer tone than the harsh bite i currently have. ( i dont want to have to buy a new head, there must be a cheaper but effective alternative :\ ... )

Not that I want to bash the JCM900, but well, been here, done that, and unless you're a tube amp wizard with some spares, the "cheaper but effective alternative" is still to sell your JCM900 (bad news: you're not going to get much out of it) and buy something else (good news: you can now find decent tube amps for dirt cheap - Fender HRDx, Jet City etc....).

My 2 cents...

[edit]
Actually I've read somewhere that you might be able to replace 5881 with KT66 without modification to the schema (you just have to get KT66 that physically fit in your amp, which is another problem). KT66 are supposed to be generally more rounded than 5881/6L6 so that might - or not - help. But I still think you'd be better with another amp.
[/edit]

[richard]

You may do a lot of work and not get the results you want. You could try an EQ pedal like the Boss GE7 to cut the highs but run it through the front of the amp not the loop which was designed for rack effects. I've also read that 900s sound better when the loop is engaged even with nothing in it - run a patch cable between the send and return.

What pickups are you using in the SG ? If they're stock Gibsons you could probably do better. Try your guitar through some different amps.

[BigB]

What pickups are you using in the SG ? If they're stock Gibsons you could probably do better. Try your guitar through some different amps.

IIRC it all started with the OP asking for advices for new pups and ending up with everyone and it's sister telling him to fix the amp's problem first :mrgreen:

[Telerocker]

What cab are you playing? Speakers can make a lot of difference.
A good drive/distortion-pedal could be a solution too. The Emma Reezafratzitz or the Brunetti Mercury-box (and of course many other good pedals) do the Marshall-thing in a nice creamy way.

[Dmoney]

If its a 900 dual reverb it's not a very warm amp. You're SG might have a 498T bridge pickup, which to be fair I don't think is such a bad pup.

You might be able to get more warmth out of the guitar with a simple pole piece adjustment on the adjustable side of the pickup. That might see you through till you can figure out what you want to do.

[gwEm]

What speakers/cab are you using?

[Alex]

The JCM900 series will always have a bit of a nasty aggressive edge to it. The EL34 version was my main amp for 10 years or so (school/student days) and I used it with exactly the same guitar mostly - SG with 498T. It is too much geared towards an aggressive metal sound with tight end to do anything else convincingly. That said, I manged to get some really good metal sounds out of it.

The 6L6 version - i thought it exists, as my bandmate had that one - sounds actually a bit warmer and fatter and has nicer cleans. We ran them side to side. I used a 1960 AV (V30s) and it made things even nastier/cutting. He used the 1960 A, which was warmer and fatter, but also less effective in the mix IMO.

[ericsabbath]

power tubes won't make its solid state distortion sound warm

and anyway, 6l6's are usually warmer sounding than el34'

as we told you on your old pickup thread, you need a proper all tube marshall

[jpfamps]

How old are the 5881s in your amp?

I could simply be that the amp is not functioning optimally; always get your amp running properly before you consider any modifications.

I'm actually not a huge fan of extensive amp modding (even though I charge people for this service!), as it often doesn't make economic sense.

Sure, if you have plenty of spare time and enjoy working on amps it can be good fun, but once you start paying someone else to do the work, then it's often cheaper simply to change your amp.

[JJretroTONEGOD]

you could try modding it, sounds like the right way to go to me, you may as well maximise the sound or just sell it and get a less harsh sounding amp. It's weird actually because I've heard a JCM900 sounding really good and one that sounded bad so they can sound good, I've heard that you are supposed to replace caps e.t.c. every 10-15 or so years but obviously most people do not do this.