SWR Interstellar Overdrive: What replacement tubes r best?

drjake · #1 08-18-2010, 04:54 AM

I've burned this baby bad for a few years of gigs and her tubes seem to be shot. I get distortion at around 10 am on the drive dial, where that would formerly just be the beginning if the meaty-crunchy sweet spot (now disappeared!). This is my first time replacing tubes and am curious to hear from anyone with some experience with this unit. It takes 2 EL84s and one 12AX7. I dont have a ton of money unless it were to make a ton of difference in the sound (looking for vintage crunch). Tx!

drjake
ur groove cure

drjake · #2 08-18-2010, 08:06 AM

http://www.swrsound.com/support/manu...rstellarod.pdf

JGR · #3 08-18-2010, 09:33 PM

I had TAD EL84's which seemed to be very robust and worked well. Play with the internal bias as well to fine tune it. Just set it where it sounds best to you.

drjake · #4 08-19-2010, 01:59 AM

Quote:

Originally Posted by JGR

I had TAD EL84's which seemed to be very robust and worked well. Play with the internal bias as well to fine tune it. Just set it where it sounds best to you.

Tx for replying JGR. I'm hoping you can enlighten me on how one goes about "playing with the internal tube bias". Is this something that one does at home? Equipment needed? Tx much!

JGR · #5 08-20-2010, 05:43 AM

There is a trimmer pot on the inside that you turn with a small screwdriver. With a normal tube amp, you wouldn't want to just turn it arbitrairaly, but it won't hurt the mini ouput section in this amp. It will help you dial in the right amount of hair and fatness. At one extreme, it will be biased cold so the power tubes will be running hotter and you will get a lot of distortion and perhaps mush. At the other extreme, they will be biased too hot, and the sound will be thinner. Just find the right spot in between.

One other note on this amp, if you plug in a speaker cab to the speaker jack on this preamp while still using it with your regular setup, the sound changes a lot. It is a lot more dynamic with more lows and highs, but I found that it was more prone to feedback. You wouldn't want to carry around a whole additional speaker, but if you like the sound, it may be cool to get something like a Weber mini mass to leave plugged into it to get some of the effect.

JR

drjake · #6 08-22-2010, 03:45 AM

Quote:

Originally Posted by JGR

There is a trimmer pot on the inside that you turn with a small screwdriver. With a normal tube amp, you wouldn't want to just turn it arbitrairaly, but it won't hurt the mini ouput section in this amp. It will help you dial in the right amount of hair and fatness.

At one extreme, it will be biased cold so the power tubes will be running hotter and you will get a lot of distortion and perhaps mush. At the other extreme, they will be biased too hot, and the sound will be thinner. Just find the right spot in between.

One other note on this amp, if you plug in a speaker cab to the speaker jack on this preamp while still using it with your regular setup, the sound changes a lot. It is a lot more dynamic with more lows and highs, but I found that it was more prone to feedback. You wouldn't want to carry around a whole additional speaker, but if you like the sound, it may be cool to get something like a Weber mini mass to leave plugged into it to get some of the effect.
JR

OK re: adjusting the tube: I do this to the pwr tubes or preamp tube or both? This is cool! But what's "hair"?

I never tried the speaker trick. I loved the sound of this things when I bought it, I suddenly had this thick sound from all those 70's rock albums. I'd love to take it further if i can. Thanks much!
yaacov

JGR · #7 08-30-2010, 09:32 PM

The trimmer just sets the bias of the two EL84's inside. Hair is just another word for overdrive/distortion.