Quote:

silent one said:

 
I'm now 11 hours in with the Syl 3DG4 and shutting it down for the morning. The tube sounds like it could use some more play-in. Maybe some 40 to 50 hours. Currently, lacking a certain smoothness, refinement and finish to notes. If the GE 3DG4 is any indication, perhaps the tube will come around shortly. Still, if it's going to compete with the USAF-596, it has some ground to cover.
 
Not sure about a European equivalent. Time to breakout your Goog-fu!

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 There is no European equivalent the only one I would try is the GZ37 it is Indirect heated and 5 volt so it won't sound the same but
it can handle the current. 350ma into a choke input load

So, there you have it rosgr63. No going to the local Market for food, and tossing in a European equivalent while you're out and about.

Quote:

2359glenn said:

 There is no European equivalent the only one I would try is the GZ37 it is Indirect heated and 5 volt so it won't sound the same but
it can handle the current. 350ma into a choke input load

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The GZ33 is also an option, it supposedly has slightly less voltage sag than the GZ37.  I didn't think it was anything special when I tried mine in the amp, sounds soft like the 5U8C.  Maybe I'll try it again to confirm that opinion.

I bet Glenn, xcalibur and SO will come up with a European alternative!

Really the 3DG4 was a brilliant find by Glenn.  Everybody (including me for a while) has spent so much time trying to find something different to use in the amp for some reason, maybe for the sake of seeking out familiarity, but I really think that all things considered the 3DG4 is the best tube in the amp.  When I try something else there is always an active desire to go back to the 3DG4, that really boils it down for me.
 
I popped the Mullard GZ33 in tonight to skim some thoughts.  I don't care for how it sounds.  The soundstage collapses in and becomes very flat, no depth.  I thought the midrange had some coloration that came off as nasal, with a spotlighting effect in the upper mids that sounded unnatural and tended to mask some lower midrange detail.  It sounds a little grainy in the highs too.  Good PRaT and bass though, except the very bottom octave feels like it missed the boat.  It doesn't sound bad, closer to the 5V3 than anything except without that tube's sweet sounding tone and less bass drive.  Oh, and a flatter and narrower sounstage.  It was pretty unengaging I have to say.  This tube has a stellar reputation too, I really liked it in my Woo.  It just goes to show that general impressions about a tube only go so far, the circuit it is in matters a lot. 
 
I'll listen to it again tomorrow before taking it out just to make sure it wasn't my ears tonight.  I have this feeling that might be part of the problem.  I felt "tuned in" last night but not tonight at all.

Thanks for the update.
Have you ever tried the GZ33 with 6AS7G's?

On the rectifier front, personally I didn't put any effort forth in looking to replace the GE 3DG4 rec. I just knew I wanted to, despite there being few choices available. And I just happen to have four USAF-596 recs lying about and...voila! The Mid-February 1957 release keeps bringing it.
 
Because I am writing about my own enjoyment, it matters little that I am the lone wolf preferring this glass for the OTL. In my view, the USAF-596 continues to be a fine find. In fairness, my NOS Sylvania 3DG4 is glowing 16 hours strong, now. Will reserve judgement until I approach 50 or hear some sort of a shift. But at this writing, both 3DG4's are slotted behind the '596' for my tastes...
 
It's almost a given, that if I make any system changes, all prefs and bets are off!  I've no shame in re-evaluating. My current 1st team remains:
 
United Electronics USAF-596
Tung-Sol 5998
Tung-Sol BGRP VT-231

I am jealous because I don't have any  USAF-596, that's all.
 
One that never changes his/her mind and is intransient despite new experiences/results is not objective and honest.

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rosgr63 said:

I am jealous because I don't have any  USAF-596, that's all.

 
One that never changes his/her mind and is intransient despite new experiences/results is not objective and honest.

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The glass is available, just numbered (rare). There's a lot more available than is on the market - Military surplus. But, they're primarily used for RF Transmitters and stuff. Earlier this year, I found a dealer who only ever had a handful in 35 to 40 years - sold all but one back then for transmitters. Never heard anyone using 'em for audio. When I inquired, he fell out of his chair in disbelief! I told him it was for a vacuum tube amplifier.  Someone actually asking about a tube he long forgot about.
 
Our fellow member Ultrainferno (Belgium) has a strong Euro connection for the USAF-596. If you'd be interested in hearing one, it can happen! While this tube isn't for everyone, I think it's worthy of being in one's inventory for current/future selection. 

@ 2359glenn
 
So far, so good! I've been running the USAF-596 in "5998 mode"  without incident.

Thanks SO.

Quote:

rosgr63 said:

Thanks for the update.
Have you ever tried the GZ33 with 6AS7G's?

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Hmm.  I  don't remember clearly.  I think I tried all the rectifiers in the beginning when I was running Chatham 6AS7s.  All I can recall is thinking it sounded soft compared to the 5AU4 and 3DG4.  I was trying to run the 5V3 at that time too.
 
The Mullard GZ33 might have been my favorite rectifier when I had my Woo, even over the EML 274B.  It just doesn't work out in this amp IMO.  I would take the 5U8C first actually, no question. 
 
They sure look pretty though, I love that slender glass.  I'm hoping it sounds very good in my next amp so I can use it.

As promised, pictures! and dust!
 
 
http://www.head-fi.org/g/a/697715/glenn-otl/
 
 
Teaser!
 

Night cats like myself  are right at home with shots like that! Congrats on entering the club!

 I have a basket full of audio goodness coming tomorrow - forgot USPS was closed today; kept looking out the door and windows for the truck!