SVT 3-Pro tube problem?

Doesn't the AU7 have significantly less gain than the AX7? Might make a difference to ya!


dcr

 

As far as the cracking goes - your first step is to clean the pots (the front panel volume and EQ controls). Use the little plastic tube to spray the contact cleaner into the rotary or slide pot, rotate or slide the pot back and forth several times, repeat. As long as you're at it, go ahead and clean the switches, too.

 

Hi.

IMLE the crackling is more likely caused by a dying electrolytic capacitor than a bad tube.
OR if the head is ROHS compliant, I'd blame the solder joints .

As for the tubes, I still life too close to be comfortable to the place they make Sovteks to use them. Paskaa, sanois Suomalainen . We were flooded with them back in the day, so my opinion may be a bit biased.

Anyway, buy one of each and roll them to find Your sound. Tone isn't something that can be described with too much accuracy IMHO.

Regards
Sam

 

New old stock:

http://www.audiotubes.com/12ax7.htm

 

Another vote for American made NOS
While my 3Pro went 10 years without problems, it has recently developed a problem that continues to be bad solder traces and apparently this is common with this amp

 

Tung-sol all the way! I haven't found a tube that can 'grit' like this one, especially for the low amount of noise it produces.

 

Are you talking about the originals or the new stuff.
The old ones go for $30+ each for used tubes (about twice what I pay for new Sylvania's and RCA's).

There was one NOS Tungsol on the 'bay last week that went for something like $75

 

+1 for tung sols

Clean the jacks while you got the q-tips and contact cleaner out - then run a clean plug in out of each one vigorously a few times - get the ones on the back side too.

 

Telefunken didn't make the list? It worked better for me than the JJ and EHX's..

 

The real deal Telefunkens go for over $100 ea., used
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=320394353323
These former high quality, European made tubes are now made in mysterious factories by our former arch enemies with dubious quality

I'm sure a tube expert can chime in and further explain that the quality of the new tubes with famous names (made by ultra low paid slaves) means nothing when compared to the same brand that were made by craftsman and engineers with pride.

 

No need to swear Sam!

I agree with your feelings that it could be a cap problem. It could also be dirty tube pins or a bad resistor.

As for the tube choice, I really don't think that any of them would stand out from the others by much if anything. My current maker of choice is JJ. I have no reason for this. In the past I have happily used Sovteks. The only time I had trouble with them was in one case where they didn't like a SRPP design I used. The JJs worked fine as did my NOS ECC83s.

Paul

 

Pre-amp tubes go for $10-15 each. That's not a lot of money by any means.

Paul

 

I have had nothing but excellent experiences with JJs and many people on here will corroborate similar experiences for others as well. I wouldn't shy away from JJ's, they are great tubes...especially the 12AX7's

 

Hi.

They really were that bad back in the day Paul, and as the GT for 5*the price was our only other option, I saw a lot of amps die because of those POS tubes. That was about 20 years ago though, so the things might have changed for the better .
But the memory remains...

Even more reason to buy a few mofre than You actually "need".
You might be surprized how little if any a same type of tube will affect the sound.

Regards
Sam