Aguilar DB750 advice

liebesfuss · #1 03-18-2013, 10:32 PM

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.

JimmyM · #2 03-18-2013, 10:45 PM

Yes it does.

liebesfuss · #3 03-18-2013, 11:47 PM

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

JimmyM · #4 03-19-2013, 12:20 AM

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.

liebesfuss · #5 03-19-2013, 07:16 AM

Thanks again so much.

jastacey · #6 03-19-2013, 08:35 AM

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

liebesfuss · #7 03-19-2013, 09:32 AM

Much appreciated.

JimmyM · #8 03-19-2013, 09:43 AM

Quote:

Originally Posted by liebesfuss

Much appreciated.

Ya, you appreciate the Telefunken advice till you price them...YOW!!

Great tubes, but man, spending $100 or more on a single tube is not my thang.

liebesfuss · #9 03-19-2013, 02:56 PM

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

JimmyM · #10 03-19-2013, 06:01 PM

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.

sunbeast · #11 03-20-2013, 12:17 AM

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!

liebesfuss · #12 03-20-2013, 02:39 AM

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.

JimmyM · #13 03-20-2013, 02:52 AM

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.

pedulla-2007 · #14 03-20-2013, 03:35 AM

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!

Chazinroch · #15 03-20-2013, 07:11 AM

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.

JimmyM · #16 03-20-2013, 01:06 PM

Quote:

Originally Posted by pedulla-2007

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