Aguilar DB750 advice
 

Hey there. My DB750 is, after about 10-15 minutes of playing, starting to distort at low settings (everything flat, Gain at 9, Volume at 12.) Nothing seems to be clipping. Does this sound like a preamp tube situation?

Thanks in advance for any help you can provide.

Yes it does.

Thank you. The kind of situation where replacing said tubes should fix it?

Maybe not even all of them. Might just be one. Why waste money? Pull them one at a time until you find a culprit, then just replace the one. Tube life is completely unpredictable, and one tube can blow tomorrow while the one next to it on the assembly line can last years.

Thanks again so much.

As a side note ... a lot of people have been using a old Telefunken 12AX7 in the V1 postion .... seems to tighten up the low end a bit, but first test the preamp tubes with a known good tube, and like said previously, pull one - insert new/test tube and repeat till problem goes away, that would be the first step

Much appreciated.

Ya, you appreciate the Telefunken advice till you price them...YOW!! :D Great tubes, but man, spending $100 or more on a single tube is not my thang.

Yikes. No kidding. Anything in particular you would recommend? Something that is not $100?

I'm totally about garden variety NOS RCA's, Sylvanias and GE's. And even though they're not popular on here for some reason, I see nothing wrong with new Sovtek and EHX tubes.

The two likely possible tube culprits would be V1, which is the tonestack/EQ tube, and V4, which is the driver tube. V1 is a 12ax7 and V4 is a 12au7. If you like the stock sound of the DB750 then just get another Sovtek- if you are interested in tightening up the low end a bit and don't want to invest in a Telefunken in V1, I really like a gold pin Tung Sol 12ax7 in mine. To tighten up the low end a bunch (too much apparently for most DB750 owners that have used them), a JJ 12ax7 works really well- this is what mine has right now. I would try switching V1 first...

For V4, I personally had an old Amperex 12au7 on hand and like it in there, though I went back and forth with the stock EHX tube and like both of them for different reasons- the EHX has a slightly more gritty and old school feel to my ears vs the smoother and flatter Amperex. Definitely more subtle than the differences between tubes in V1 though.

Good luck!

Well, this has been my first time posting, and I'm simply knocked out by all the help. With sunbeast's (as well as Aguilar's) advice I decided to get a couple 12AU7's (Amperex 12AU7 and EH 12AU7A) and a couple 12AX7s (EH 12AX7 and Preferred Series 7025/12AX7.) Anyone experienced that last one? Can't find much on them, but this purchase gives me the proven back up for each type, as well as a cautious venturing into this brave new world with the other pair. Finger's crossed. If anything mind-blowing occurs, I'll let y'all know.

And thanks again.

I'm sure the Preferred Series tube will be lovely, but they're really just relabeled Chinese tubes that have probably been burned in and tested more rigorously by The Tube Store. I was reading some pages about them, and apparently they're available under a couple different names for cheaper:

http://www.thegearpage.net/board/arc.../t-815137.html

No big whoop, though, only a few dollars difference.

Holy Cow!
 

Does Jimmy know his stuff or what? Just bought a DB 750, and I am sure glad this guy is around. Great thread for those completely in the "tube", dark!

I have a DB750 and had the same issue..it was the V1 tube. Unfortunately I had a Telefunken in V1 when it went. Had to replace it with the original tube. Very minimal difference to me, but noticeable.

I know a small fraction compared to some folks on here, but thanks, bro! ;)