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Eddie Current Zana Deux owners
Feb 9, 2009 at 10:11 PM Post #977 of 2,605
The 6BL7/6BX7 tubes I refer to are used as output tubes in Purk's SDS (and now my old SDS after the upgrade) with a modification to run them at a higher voltage. They make a substantial improvement in those amps' sound, but especially in their ability to drive low impedance headphones like the Sony R10. The 6BL7/6BX7 is a badass powerful tube in comparison to the 6sn7/5687 output tubes we'd previously been using in those amps.

Now, the 6c33c's used in the Zana are completely badass output tubes, heck they're used as output tubes in speaker amps, too. The Zana's output impedance is 16 ohms which is very low for an OTL tube headamp, and as much as I love the sound of the modified SDS amps - I doubt they get that low. So I'd guess the Zana should be able to drive 20-25 ohms no problem - it's when you start getting headphones much lower than the amp's output impedance when you have to worry about the issues. The lowest impedance headphones I've used the Zana with are the HP2 (40 ohms), L3000 (48) and Qualia (I think 32?) - it sounded very clean & powerful with all.

Speaking of the 6c33c, I'm not very educated on the variants. However, I got my amp with well-used 6c33c-b tubes, and used them quite a bit myself. They must have had 3000+ hours on them when I replaced them with a fresh set of winged-C 6c18c last week. I can't give a worthwhile comparison because the 6c33c's were at the end of their useful life and the Zana had recently seemed to lose its "edge" with them. Now it sounds fantastic, again
smily_headphones1.gif
 
Feb 10, 2009 at 2:31 AM Post #979 of 2,605
sorry for the confusion, i meant using different brands/vintages of 6c33b's not totally diff tubes. would never dream of doing that unless "authorised" by Craig.
smily_headphones1.gif


another poster, i think on the tube rolling thread, suggested using adiff tube instead of the 6sl7, i checked with Craig and got a "don't do it" response. I reckon he would say the same about this...
 
Feb 10, 2009 at 3:42 AM Post #981 of 2,605
Quote:

Originally Posted by mulveling /img/forum/go_quote.gif
The 6BL7/6BX7 tubes I refer to are used as output tubes in Purk's SDS (and now my old SDS after the upgrade) with a modification to run them at a higher voltage. They make a substantial improvement in those amps' sound, but especially in their ability to drive low impedance headphones like the Sony R10. The 6BL7/6BX7 is a badass powerful tube in comparison to the 6sn7/5687 output tubes we'd previously been using in those amps.


 Quote:

Originally Posted by mulveling /img/forum/go_quote.gif

So, are you saying the 6BL7/6BX7 tubes are not for use in the Zana, and I needn't concern myself with them? I wanna hear an R10
frown.gif
.

Now, the 6c33c's used in the Zana are completely badass output tubes, heck they're used as output tubes in speaker amps, too. The Zana's output impedance is 16 ohms which is very low for an OTL tube headamp, and as much as I love the sound of the modified SDS amps - I doubt they get that low. So I'd guess the Zana should be able to drive 20-25 ohms no problem - it's when you start getting headphones much lower than the amp's output impedance when you have to worry about the issues. The lowest impedance headphones I've used the Zana with are the HP2 (40 ohms), L3000 (48) and Qualia (I think 32?) - it sounded very clean & powerful with all.

But didn't you (or was it someone else) say the HP-1s distort before getting real loud on a Zana? I'm guessing those are 32-40 ohm. (Or maybe that was an earlier Zana with different tubes, I think they said differnt tubes remedied this. If relevent to the current Zana I'd be interested which tubes)

Speaking of the 6c33c, I'm not very educated on the variants. However, I got my amp with well-used 6c33c-b tubes, and used them quite a bit myself. They must have had 3000+ hours on them when I replaced them with a fresh set of winged-C 6c18c last week. I can't give a worthwhile comparison because the 6c33c's were at the end of their useful life and the Zana had recently seemed to lose its "edge" with them. Now it sounds fantastic, again
smily_headphones1.gif




How do you know when tubes are near the end of their useful life? Is it as gradual and subtle as you say, with the amp seeming to loose its edge?
And thanks back there, for pointing out the "search thread" option, my eyes are already shot now anyway
cool.gif
(that's a blind-guy smiley).
 
Feb 10, 2009 at 4:21 AM Post #982 of 2,605
Quote:

Originally Posted by billyearle /img/forum/go_quote.gif
How do you know when tubes are near the end of their useful life? Is it as gradual and subtle as you say, with the amp seeming to loose its edge?
And thanks back there, for pointing out the "search thread" option, my eyes are already shot now anyway
cool.gif
(that's a blind-guy smiley).


In this case I had no obvious indicator, other than the feeling/observation that the amp wasn't performing at the level it had been and should be at. That and the previous owner indicated he'd put 1500+ hours on those tubes, plus quite a bit I'd put on myself. I'd replaced the 6sl7 and power rectifier tubes recent-ish, so that stuff should be solid.

A few weeks ago, (while listening to Kiss's "Great Expectations" on vinyl & speakers, haha) I noticed a high level of overt distortion during the chorus that I didn't remember being in that recording. Sounded kinda like when you try to drive a low-impedance headphone with a much too high output impedance. That shouldn't happen with the Zana, especially as a preamp. Since I didn't have spare 6c33c's at that time I swapped the 6sl7 tube and it seemed to get a bit better. But still, upon further listening the amp sounded like it to came down a notch from where it should be.

Another thing is that many of the new 6c33c's have purple diamond markings - on these old tubes they'd faded to a very dull rust color which you can see in my photos (though they were like that when I got the amp, so I'm not sure how many hours this takes).

With smaller tubes on my toaster SDS I've had the heater die out during listening, which caused one channel of music to rapidly fade to silence (happened to me TWICE with the expensive 6sn7 Tung-Sol roundplates). Actually, I got those Tung-Sols to work again, but they never got that "magic" sound back, and a local tech later tested them to confirm that they were in fact at/near death. Another time I had a Sylvania gold-pin 12AY7/12AT7-like (forgot the specific variant) input tube start out with a soft noise that sounded like "rustling leaves", which grew up to full blown, LOUD scratching sounds....that tube came out QUICK!

Definitely a good idea to have a set of spares on hand!
 
Feb 10, 2009 at 3:26 PM Post #983 of 2,605
The first thing to do in all situations is to clean all of your contact. This includes interconnects as well as tube pins. One way to be sure the contacts are always in their best shape is to clean them and then apply Xtreme Quicksilver. This compound forms a permanent connection and doesn't then need to be cleaned again. It's practically like soldering the contacts together. It does take a couple hundred hours to really reach its greatest SQ level, but even right away it will be better than not having applied it.
 
Feb 12, 2009 at 4:43 AM Post #984 of 2,605
Quote:

Originally Posted by BobMajor /img/forum/go_quote.gif
The first thing to do in all situations is to clean all of your contact. This includes interconnects as well as tube pins. One way to be sure the contacts are always in their best shape is to clean them and then apply Xtreme Quicksilver. This compound forms a permanent connection and doesn't then need to be cleaned again. It's practically like soldering the contacts together. It does take a couple hundred hours to really reach its greatest SQ level, but even right away it will be better than not having applied it.


But what if I wan't to switch around my system and remove the interconnect and re-attach it?
 
Feb 12, 2009 at 7:47 AM Post #986 of 2,605
Quote:

Originally Posted by dallan /img/forum/go_quote.gif
Couldn't wait, put in the new tube last night, could barely force myself to go to bed for work in the morning.
L3000.gif



Hehe. Let me guess... Valvo?
 
Feb 12, 2009 at 8:05 PM Post #989 of 2,605
Quote:

Originally Posted by dallan /img/forum/go_quote.gif
Yes the Valvos came, holy moley (as my dad used to say in his corny moments).


IMO, there is no better tube for taking away that harshness and edge. Very musical sounding tubes, and really good regarding sss and ssh sounds.
 
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