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Sovtek 6550 - Can they really be THIS bad???

Hello.

Just picked up a new Jadis today, and I'm none too pleased with the sound. As I have had blissful sonic experiences with two of the models lower on the Totem Pole from this manufacturer, the only thing I can trace it to is the Sovtek 6550. Can they really be THIS bad???

I already switched out the JAN Philips 12AX7 and Golden Dragon 12AU7 for Mullard Blackburn and Ei respectively. The improvement has been subtle, but it still ain't working for me...

I have used ElectroHarmonix 6550 in the past, and while they didn't float my boat, I'm told that EH represents a signficant step up from the regular old Sovteks. JJ E34L and KT88 just have sounded really splendid to me. So, now I'm looking at picking up 8 new output tubes if I don't wish to live with such uninspired sound.
trelja
ubglub
76 posts
 
Joe, I might forget about this. Send me an email message in a week or two. If the amp isn't back I should at least have an ETA. Bob
trelja OP
3,223 posts
 
Bob, will you be coming over next Saturday??? Hopefully, the answer is yes.

I did try the Sovtek 6550s in the DA30 last night, and I must say that while the amp runs out of steam before its big brother, though still within the limits of being acceptable to all but the really power thirsty, it's simply a better component sonically. Even with these tubes, while not as glorious as the JJ KT88, the sound was commendable. Despite its homely looks, whatever purity was designed into it originally, later iterations seem to have lost to some degree. Not that the DA60 is not a very good amp, it is, just that the older amp is INCREDIBLY special. The sweetness, naturalness, and even excitement is wonderful. I guess, sometimes, the old stuff really is that good.
bezimienny
53 posts
 
Hi Trelja. Thanks for mentioning the possibility of the JOR being "loose" - I took this to mean that the little bolts on the casing could be loose, and sure enough tightening them virtually eradicated the hum - presumably the service guy who biased the new tubes left them a bit undone and so the casing amplified whatever resonance the transformer was creating.
*
Hope your new amp works out. Regards, Rob.
trelja OP
3,223 posts
 
Rob, I'm so happy about the JOR not having a "real" transformer issue. That would be quite painful.

You read me 100% correct in my saying "loose" meaing what you thought it meant. My idiotic ramblings are so all over the place, it's a wonder anyone can understand me sometimes. It's easy to see how a loose transformer could really buzz. The biasing of the amp should not involve loosening the transformers whatsoever, only reading a few resistors, and adjusting the respective potentiometers until the voltages on those resistors falls into spec. Still, I'm sure it could have loosened any number of ways.

Good luck with that JOR, it's one of the finest sounding amps I have ever encountered, if not the finest.
ubglub
76 posts
 
Joe,
I need to make a correction. I think the stock tubes for my CAT JL-2 are 6922--and I haven't changed them.
You're still welcome to come over and have a listen of course.
Bob
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