20th xtc bias question

GOHOINC

GOHOINC

Well-known member
On friday i found that my 20th xtc el34 have 2 of its winged c s red plate. Amazon had jj e34ls in stock with delivery available today (sunday) so i figured what the heck. Swapped them in and checked bias with my bias rite and found that with bias pot bottomed out im still pulling 37ma. I figured id still give it a whirl so i played for a little bit, sounded great. Question is, should i leave it or take it to a tech and have it checked and fixed properly? My understanding is these tubes should probably be running around 35 ma...
 
Depends on the tube and the pV and the interaction of the two.

I run KT77s at 31-32mA in this amp for perfection in tone. Anything under 30mA feels to "knocky", and anything over 34-35mA is too compressed right out the gates.

YMMV - but ask me anything you want about this amp.... I've owned one since they first came out, and still have it to this day as my all time fave amp.
 
Well, the quad I bought lasted about 3 weeks and two of them redplated as well. I took it to a local tech, he thinks the quad I bought may have had a bad pair and when they went, they took out a cathode resistor as well. In any case, he put in a fresh quad of E34Ls and its back up breathing fire and running cooler...
 
GOHOINC":yy8gqldz said:
Well, the quad I bought lasted about 3 weeks and two of them redplated as well. I took it to a local tech, he thinks the quad I bought may have had a bad pair and when they went, they took out a cathode resistor as well. In any case, he put in a fresh quad of E34Ls and its back up breathing fire and running cooler...
Click to expand...
Did you do the initial install and bias of the ones that got shot?? Redplated?? Weber Bias-Rite or shunt??

Just asking...
 
I did the initial and used a weber bias rite. Ive retubed and biased a bunch of amps in the years ive had my bias rite but this is the first ecstasy i had ever done. Iused the bias rite on my vh4s, a soldano, orange, b52, marshalls, dr. Zs etc. First issue ive had after doing a job so i dont think it was me or my tools but i guess you never know..
 
GOHOINC":1nadjt7m said:
I did the initial and used a weber bias rite. Ive retubed and biased a bunch of amps in the years ive had my bias rite but this is the first ecstasy i had ever done. Iused the bias rite on my vh4s, a soldano, orange, b52, marshalls, dr. Zs etc. First issue ive had after doing a job so i dont think it was me or my tools but i guess you never know..
Click to expand...
Likely bad bottles then. Should be able to run quality bottles up to 35mA no sweat. even higher if need be. But I tend to dig mine around 31-32mA as it's less compressed sounding. But whatever, get 'em in there and give 'er. It's not the tubes - it's the playing that matters :rock:
 
Even with the high plate voltage in the XTC 35mA should not be a problem. I run my Classic in Class A mode. The bias in class A mode is up near 90mA. I was running Ruby EL34's for years and getting 9months to a year out of them. Now I use Gold Lion KT77's and they've been going strong for over a year...
 
You must log in or register to reply here.
Back
Top