HELP JCM 800 2203x Preamp tubes

[Cameronc20]

Hi guys new to this so here goes got a jcm 800 and its never been revalued the amps sounding **** harsh trebly and no sweet sounds harmonic-less what's the best preamps current production as I ain't loaded ATM lol thanks any help will be much appreciated.

 

[Johtosotku]

Re: HELP JCM 800 2203x Preamp tubes

I like Tung-Sols. If the anp has never been revalved before I'd change the power tubes first. They typically get worn out much faster than preamp tubes.

 

[dystrust]

Re: HELP JCM 800 2203x Preamp tubes

You may not need to replace the power tubes, but you should have the amp checked out by a tech. A few years ago my Jubilee started sounding like that, and it turns out the bias had drifted colder than January in Minnesota.

 

[Cameronc20]

Re: HELP JCM 800 2203x Preamp tubes

Thanks thought tung sols would be mentioned lol right I will put in some tung sols in preamp any recommendations for power tubes

 

[Cameronc20]

Re: HELP JCM 800 2203x Preamp tubes

Yea my jcm is 2007 never been revalved bedroom volume but on and off a lot

 

[Gone_Shootin]

Re: HELP JCM 800 2203x Preamp tubes

+1 on the Tung-Sols, they'rey favorite preamp tubes, and their EL34s are the next on my list to try when my JVM needs new power tubes.

Currently, my JVM has the Marshall labeled SED Winged Cs it came with, which are great tubes, but they're no longer produced so the price has gone up considerably and it's been said quite a bit that the quality suffered towards the end.

My Mesa Recto has the Svetlana EL34s in it I bought for it last year. They're a tube that has a really tight bottom end, which that amp needed to tighten up the low end flub it has with 6L6s. I love 'em in the Recto, but I'm not too sure they'd sound as good in a JCM800.

ETA: And yes, check your bias. A cold bias will make any amp sound thin and brittle.

 

[Johtosotku]

Re: HELP JCM 800 2203x Preamp tubes

Yea my jcm is 2007 never been revalved bedroom volume but on and off a lot

Are you planning on playing it only at bedroom volume after you change the valves? I'm afraid jcm800s need to be opened up to serious volume to give their best. Your problem may not be the tubes but a wrong tool for the job, that being a big amp in a bedroom.

 

[King IzzO)))]

Re: HELP JCM 800 2203x Preamp tubes

I actually like chinese tubes in them, but RFT's in 800 type amps are the best. For bedroom use that would be a total waste. JJ are about the darkest you'll find, throw in for a high gain and you should be good.

That said, as was stated, those amps actually sound pretty ****ty until you run them loud, then the magic happens.

Get a different amp for the bedroom.

 

[King IzzO)))]

Re: HELP JCM 800 2203x Preamp tubes

...also, isn't there a problem with running New Sensor tubes in that circuit? Cathode follower problem or something?

 

[zzmoore]

Re: HELP JCM 800 2203x Preamp tubes

...also, isn't there a problem with running New Sensor tubes in that circuit? Cathode follower problem or something?

Yeah.....their pre tubes will not stand up the the CF position...they cannot take the big filament to cathode voltage.
And yeah again...the OP is a bit hard to understand...is this a "bedroom" amp.?
Even that term is Vague/Meaningless. People just need to say what kind of volume constraints they have.
good luck

 

[Gearjoneser]

Re: HELP JCM 800 2203x Preamp tubes

Tungsol if you can spend a little more. JJ's are the best bang for buck and they sound good too.
I'd use regular EL-34's rather than E-34L's (10% higher output) because that amp doesn't need any more volume or headroom.

Get a mA bias tool and a volt/ohm/amp meter, and turn the chassis upside down with books supporting the transformers. Plug it into the guitar and cabinet, and let the amp warm up and settle. Get the tubes running at 36mA. It's possible yours have drifted down to 25mA making it sound cold and weak.

One cheap pedal that will make that amp have optimum gain at bedroom volume is the Marshall Gov'nor II. It's voiced with the JCM 800 sound, so it melts into the preamp section just right. The Barber Ltd. and Way Huge Green Rhino also make a JCM 800 sound great.

 

[B2D]

Re: HELP JCM 800 2203x Preamp tubes

I has that same problem with an old 2203 and some Sovtek 12AX7 tubes in the preamp section took care of it.

Start with inexpensive solutions first before moving on to $pendy $olutions.

 

[Gone_Shootin]

Re: HELP JCM 800 2203x Preamp tubes

Oh yeah, I forgot, I like a JJ 12AX7 in the Phase Inverter hole because they give my amps a little more growl than other tubes I've tried in that position.