EHX 12AX7EH tubes in SVT-3 Pro

Andrew266 · #1 07-20-2010, 01:46 PM

Has anyone tried using EHX 12AX7EH tubes in a SVT-3 Pro. Thinking my amp is due for some new tubes bought it used and had ti for about a year now.

Any other suggestions?

The ampeg site says It has the following:
Preamp: Tubes (3 x 12AX7)
Driver Tubes: 1 x 12AX7, 1 x 12AU7

Luis Fabara · #2 07-20-2010, 02:20 PM

Electro Harmonix is mostly Sovtek Tubes. Most people are going to say go with JJ/Tesla.

I have some experience with the SVP PRO, and I just got the SVT-3 PRO that uses the same 3 tubes for the gain and pre.. and the same driver tube but for different purposes.

You can pretty much use any good 12AX7/ECC83(Sovtek, Tung Sol,Mullard) in V2 and V3. V1 is a little more important, so use the least microphonic/lowest noise tube you can get with good to high gain. I opted for a Tung Sol in V1.

The driver tube is trickier. In the SVP PRO only the Harmonix would work apropiately, so you could stick with those, or try a very high quality NOS 12AU7/7316/ECC82/5963
Amperex, RCA, Sylvania , Phillips/Jan.

I tried a full set of JJs ECC83 and ECC82 in my SVP PRO, i ended up only using 1 ECC83 in the V3 most of them had a higher noise floor and tended to overdrive easily.
The ECC82 was noisy so, I personally would go with Tung Sols if going for new stock tubes.

Andrew266 · #3 07-20-2010, 02:23 PM

That is some great information. I'm kind of a newbie to tubes so this def sheds some light on this. So they don't all have to be the same brand/ratings as long as they are 12AX7?

Luis Fabara · #4 07-20-2010, 03:49 PM

No they dont , you can mix and match in the neverending quest for tone.

You can buy a tube for $7 or $200 depending if its a chinnese crap or a Vintage Amperex or Telefunken.

JimmyM · #5 07-20-2010, 11:35 PM

not only that, but don't fall into the trap of regular retubing once a year. it's just a gimmick to try to get people to buy tubes. your tubes will let you know when they're toasted, and generally only one toasts at a time. so just buy a couple spares, maybe try swapping them out to see if you like the tones better, but it's not necessary to replace tubes regularly.

vin*tone · #6 07-21-2010, 03:07 AM

Do you know what's in there? A lot of SVT 3s have EHX tubes in already.

jelenko · #7 07-21-2010, 03:17 AM

preamp tubes dont go bad ever. well, not in less than a decade. i doubt your tubes need changeing, but if you want to experiment with tone - go ahead.

Groover · #8 07-21-2010, 07:13 AM

Quote:

Originally Posted by vin*tone

Do you know what's in there? A lot of SVT 3s have EHX tubes in already.

Yup, that's what mine had. I also agree with try different ones and see what works best.

JimmyM · #9 07-21-2010, 02:19 PM

Quote:

Originally Posted by jelenko

preamp tubes dont go bad ever. well, not in less than a decade. i doubt your tubes need changeing, but if you want to experiment with tone - go ahead.

well i've occasionally had tubes go bad in 3 months, but generally i think you're right that they don't go bad as quickly as people think they do.

Andrew266 · #10 07-21-2010, 02:24 PM

Not sure I picked it up used probably the stock tubes. I got to open it up and take a look. I was feeling that they may need to be replaced the amp seems to take a while to turn on. You'll here a click after a 30 to 45 seconds then get sound. Didn't think a non all tube amp took that long. Maybe its just the tubes heating up?

JimmyM · #11 07-21-2010, 02:33 PM

that's exactly what it is. even preamp tubes need to warm up and can be damaged if you play through it before they warm up. so they have a 30 second relay to keep that from happening.

BassmanAd · #12 07-21-2010, 02:39 PM

Quote:

Originally Posted by JimmyM

that's exactly what it is. even preamp tubes need to warm up and can be damaged if you play through it before they warm up. so they have a 30 second relay to keep that from happening.

What JimmyM said.

I thought my 3-Pro was faulty when I first used it because the relay took so long to come on. That said, I think my tubes are now on the way out. I get a sound not unlike the rumble of very distant thunder constantly coming from the amp. Someone will correct me if I'm wrong but I think this is what the pre amp tubes do when they've had enough.

Does anyone know if this is a user-servicable fix or is it worth taking to a tech? I'm not so good with amps...

JimmyM · #13 07-21-2010, 02:44 PM

pre tubes require no special service, so pop the lid and change them.

BassmanAd · #14 07-21-2010, 02:46 PM

Thanks Jimmy. If I forget to unplug the mains before I do it, it was nice knowing y'all.

Andrew266 · #15 07-21-2010, 02:58 PM

The EHX Tubes say "High gain preamplifier tube with ultra low noise" are these intended for guitar amps? Will it sound weird in a bass amp?

JimmyM · #16 07-21-2010, 03:13 PM

tubes is tubes and aren't application specific.