Pre-amp tube recommendations for 18 Watter?

[Pedro58]

I have a TMB 18 Watter built from a GDS Kit. I run it in a combo with a Celestion Blue 12" and a Weber Silver Pup 10". It is a killer amp. The Marshall-voiced side has one tone knob and a volume. It runs from a 12AX7. I tried a GT/Mullard copy and it was too smooth. No high end. I have a JJ ECC83-S in it and it sounds good, but the high end isn't there until you turn the volume WAY up and get crunch. I would like a 12AX7 that has some sparkle before it gets really driven. A good clean tone... Any suggestions? I would like to have it on the edge of breakup and have some sparkle.

 

[TAVD]

Interesting. Both of my 18 watters lose high end when the volume is turned up. I'm using a Westinghouse branded tube in one and a RCA in the other.

One of mine really opened up after I changed the tone pot from 250k to 1m.

 

[Swarty]

Short plate Mullards and Amperex are typically quite bright. I've got a bunch collecting dust, send me email if you're interested.

 

[goneracin]

A telefunken 12ax7 will add sparkle and high end. They are hard to find without getting a microphonic one, but a non microphonic one sounds like what you are looking for.

 

[Pedro58]

e-mail sent...

Anything that isn't NOS?

 

[goneracin]

an EH 12ax7 is usually brighter than the jj's. Also, the new jj ecc803 is a decent tube IF you can get a non microphonic one.

 

[TAVD]

Sovtek are bright although I find them harsh in most amps. Funny, I don't usually think of EH as being bright. They do seem to have more gain though.

 

[Pedro58]

Denyle-Guitars-- I think I'll look into the tone pot. I'm not sure what mine is...

 

[Blue Strat]

Microphonic Telefunkens? Nothing is immune from problems, but you've had abnormally bad luck (or you don't have real Telefunkens).

In new tubes, the EHs and Ruby STR 7025s are candidates.

 

[Pedro58]

Okay, I tried the Ruby 7025... still not enough top end. I think I'll try hte larger value pot. When I go to a 1 Meg, do I need to stick with audio taper or do I go with linear? It seems that most suppliers have a 1 Meg linear only... Is there a reason for that?

 

[phsyconoodler]

I find that the speaker is a BIG change in high end response.What speaker are you using?I have tried everything from a celestion vintage 30 to a randall jaguar(my fav) to a Cannabis rex(very nice too)in my 18 watter. All except the randall has high end sparkle.Maybe you have a bypass cap thet is too high a rating,letting only lows by in the frequency range.What are you using for a cathode bypass cap?

Note: Heyboer transformers are notoriously dark.

 

[Pedro58]

I'm using a Celestion Blue and a Weber Silver Pup... It's a GDS kit, so the trannies are Heyboer, I think. But the TMB side has plenty of top end... I still think a simple pot change might do the trick. The amp isn't dark. I just need the treble frequencies to open up a little. I'll probably purchase both kinds, linear & audio taper, and see what gets what I want.

 

[jrigg]

Another vote here for NOS tubes. I have tried multiple Mullards, Amperex, Valvo, Telefunken, RCA, Sylvania, Tung-Sol, Raytheon etc in all positions and the great thing about the 18 watt format is you can really hear the difference good tubes make. Right now I am using an Amperex in V1 and a Telefunken as the PI with a RCA blackplate for the trem channel. Power tubes are late 50's Sylvania blackplates.