[BobMajor]

I should have clarified that the 6SU7GT is an equivalent to the 6SL7GT. It was supposed to be a rugged version of the 6SL7. Also the tubes marked JAN (Joint Army Navy) were also supposed to be more rugged than consumer tubes however pretty much all tubes from that era are these left over military tubes since so many were made and stock piled.

 

[Pepsi]

ahhh, i see. Thanks for clearing that up.

You haven't told me which one did you prefer tho?

btw i see you're iowa, you should the "Head-Fi Iowa" group!

 

[BobMajor]

This depends on your musical preferences.
I listen almost exclusively to classical music so I want a completely neutral, analytical sound to bring out the nuance of the recordings which are made in concert halls not studios.
For this I prefer the Brimar although the Valvo is also good for this.
Various popular music genres have different recorded sounds and people have different tastes in what they want the music to sound like. Analytical reproduction of popular music is sometimes found by listeners to be cold and uninvolving. I'm afraid that this is due to the recording engineers not the playback equipment.
The Zana Deux SE, being an OTL (Output transformer-less) design is very good at being analytical although using a tube such as a vintage Tung-Sol black glass tube will add warmth and a seductive but artificial ambience to the sound.
Different transformer output designs (OPT) add artificial lushness to the sound played back. From reading about Craig Uthus' Zana Deux ZDT (transformer coupled output amp) it has more somewhat more body to the sound than the ZD SE, but not distorted as some cheaper tube transformer amps, but it's all a matter of individual taste. Not having heard the ZDT I can't say whether I would find this to be as natural for classical recordings as the ZD SE.

 

[nghows]

Pepsi,
 
please note that the photo you posted are of 6v6gt NOT the 6sl7gt.... I was wondering why the black glass looked different/strange.
Quote:

Quote:

Originally Posted by BobMajor /img/forum/go_quote.gif The only tube which is switched is the small 6SL7 in the front between the two large 6C33C tubes. The 6SL7 comes in many different flavors and qualities. I don't know what tube Craig is putting in the amp now for the 6SL7 but the best tubes are somewhat pricey so if you look at this tread and the ZD tube rolling thread: http://www.head-fi.org/forums/f113/e...-share-297795/ you will see people recommending many tubes. The most neutral and transparent are the Brimar, Valvo and Swedish Standard. The Mullard ECC35 (a 6SL7 equivalent) is slightly warm and slightly euphonic and completely expensive! The original 1940s 1950s TungSol black glass is quite rare but has a wonderful warm and euphonic presentation. Less interesting warm and euphonic tubes include old RCA, National Union and Sylvania tubes. In general newer tubes by TungSol etc. don't have as refined a sound as the ones made from 1940 to 1965.

I find the black glass tung sol's quite interesting and have sparked my curiosity. Which of those in particular would you go for? And also, are these the black glass tubes you stated earlier?

 

[BobMajor]

The tube shown above is not like the Tung-Sol black glass. This looks a lot like a National Union black glass that I tried. I didn't like it at all. It sounded like the music was being projected from under water!.
Here is the Tung-Sol black glass I was referring to:
http://cgi.ebay.com/NOS-Military-Brown-Base-Tung-Sol-6SU7GT-Audio-Amp-Tube-/190404439863?cmd=ViewItem&pt=Vintage_Electronics_R2&hash=item2c54fd2f37

 

[dallan]

I have the Tung-Sol and used it a bit.  Gotta say though for the last 6 or 8 months i have just defaulted to the Valvo's.  I bought a matched set when I ordered the Zana Duex and then rolled for a while.  Now I am back to them, one I have used, the other sits brand new NOS, i guess as a back up if i ever need one.

 

[nghows]

Hi,
 
Need some help, my ZD #45 has blown 2 sets of rectifiers within a month. Other 3 tubes still ok, lit up but no sound. Both "L&R" rectifiers blow at the same time
 
I've emailed Craig.
Whilst I wait for his reply, thought I'd post here and see if anyone could help with why this is happening and what to do....
 

 

[Clayton SF]

Quote:

Hi,
 
Need some help, my ZD #45 has blown 2 sets of rectifiers within a month. Other 3 tubes still ok, lit up but no sound. Both "L&R" rectifiers blow at the same time
 
I've emailed Craig.
Whilst I wait for his reply, thought I'd post here and see if anyone could help with why this is happening and what to do....
 

Which ZD run was #45 part of?
 

 

[ironbut]

Check to be sure that you have you umbilical cord connected correctly on both ends. The connector will allow you to hook it up the wrong way.
It could aways be that the diode dampers you've tried were bad or just about done. Did you buy them from the same place or was one the stock one and the other one from somewhere else?
Aside from that, you'll probably have to send it to Craig. It could be a defective transformer.
Unless it's the umbilical, I wouldn't turn it on.

 

[Uncle Erik]

Quote:

Which ZD run was #45 part of?
 

I think it was in the same run that mine (#47) was in.  If I recall, I ordered it at the end of 2007 and got it in early 2008.  I've managed to burn out a 6SL7 so far, but the 6C33Cs and rectifiers are still going strong.

 

[nghows]

Umbilical cord hasn't been touched in many many months and the ZD was working fine for all this time. but for the sake of completeness will check again.
Rectifiers were from 2 different sources.
 
Unfortunately, you may be right as a 3rd set of rectifiers doesn't work at all.... But I want to cover all bases 1st as it's darn expensive to ship it back to Craig from Singapore....
 
Quote:

Check to be sure that you have you umbilical cord connected correctly on both ends. The connector will allow you to hook it up the wrong way.
It could aways be that the diode dampers you've tried were bad or just about done. Did you buy them from the same place or was one the stock one and the other one from somewhere else?
Aside from that, you'll probably have to send it to Craig. It could be a defective transformer.
Unless it's the umbilical, I wouldn't turn it on.

 

[ironbut]

Go ahead and switch out the other tubes. You could have a short in one of them somewhere in which case you're probably lucky if it's only the rectifier diodes.
If it is a short in one of the tubes, you might still be seeing the filaments glowing but the high voltage circuit which is rectified by those diode tubes wouldn't work.
Like I said before, try not to run the amp anymore than you have to. You don't want to destroy the transformer (that's what's in the power supply chassis).
BTW Any funny smells/sounds coming from either chassis?
 
If you have a reliable audio repair guy, most power supply issues aren't exactly rocket science. Once you get hold of Craig, let him know the situation and give the repair guy a way to contact Craig. There just aren't that many components in the power supply (a couple of resistors, 4 chokes, a transformer and six big ass film caps.

 

[nghows]

Well Craig asked about the tubes as well and so i recall rolling the 6sl7 not long ago. Swopped that and voila all is working again!
 
Now to find out if the other rectifiers are truly dead.... and also another Nat Union vt-229.
 
Thanks for all the suggestions.

 

[Karo]

Honey Red /  Mahogany 2

 
 
Oatmeal ...... getchu some wood man.
 
 

  
 
 

 
 
 

 

[Clayton SF]

Hey y'all. My Zana Deux SE just got delivered (so says my neighbor because it is sitting in front of my apartment). I can't wait to rev it up when I get home tonight. I find the following instructions for the ZDse unusual.

 
The first time you power up, insert the 6C33C-B’s, and the 6SL7. Leave the rectifier tubes out. The front panel light should come on, and the heaters in all tubes should be visible after a few minutes. Let the amp run for five minutes, and then power down. Insert the rectifier tubes, power the amp on, and listen to music.
 
I wonder what that does and why you have to leave the rectifier tubes out. Anyway, I'll be enjoying the music tonight.