[grmnasasin0227]

Hey gents,
 
On Woo's site on the WA6-SE page, 6EM7 tubes can be bundled as an addon with the unit described as "the ultimate driver/power tube for the WA6-SE." I know that Jack knows his stuff and isn't interested in making broad claims, but can anyone comment that this style of tube is pretty great for the amp? With so many to choose from (the tube compatibility chart lists 7 drive/power tubes as being ok), it seems hard to nail down the "perfect tube." What does it sound like, comparatively? And even then, what manufacturer should be chosen?
 
As a general side question, where do you guys shop for your tubes (aside from directly from other members )?

 

[Gradofan2]

The Raytheon and Sylvania 6EW7 tubes are great - high resolution, clear, detailed, great mids and highs.  The bass is good, but not as good as the 6DE7's, 6CY7's... and... the "grand-daddy of them all" - the 6FD7's.  The Sylvania and RCA (and probably Raytheon) 6FD7's have it all!
 
But... Jack has to up the values of one set of caps (don't recall which one's - cathode caps, I think), to 200v caps to safely use the 6FD7's. 
 
But... it's worth it. 
 
UPDATE:  Ooops... I miss-read your post... thought you were asking about the 6EW7, not the 6EM7.  I'm assuming it sounds as good as the 6FD7's, or Jack would not promote it so highly, he'd promote the 6FD7's.  I suspect the mod / upgrade he mentions is the cathode cap mod / upgrade to up the value to drive the 6FD7's and 6EM7's safely...

 

[grmnasasin0227]

From looking more closely at the product page, he only mentions a mod (and adapter) for the 6EM7, not the 6FD7. On his tube compatibility chart, Jack states that the 6FD7 doesn't need an adapter, so wouldn't the 6FD7 be able to run stock?
 
But as for the mod needed for the 6EM7, there's no listed cost for this...do you know how much the mod would cost offhand?
 
And as for tube rolling, where do you prefer to buy them? Google searches aren't yielding any sites that sell matched tubes of the variety and pinout for headphone amps from what I can find.
 
Thanks!

 

[bobeau]

FWIW, there is one impression of this tube in the big Woo thread.  I recall the poster mentioned it's worth trying out but doesn't really qualify why.

 

[Gradofan2]

 
Quote:

From looking more closely at the product page, he only mentions a mod (and adapter) for the 6EM7, not the 6FD7. On his tube compatibility chart, Jack states that the 6FD7 doesn't need an adapter, so wouldn't the 6FD7 be able to run stock?
 
But as for the mod needed for the 6EM7, there's no listed cost for this...do you know how much the mod would cost offhand?
 
And as for tube rolling, where do you prefer to buy them? Google searches aren't yielding any sites that sell matched tubes of the variety and pinout for headphone amps from what I can find.
 
Thanks!

The mod I'm referring to is likely an upgrade, which Jack made some time ago (he refers to the SN beginning the upgrade) - upsizing the cathode caps to handle the current or voltage draw of the 6FD7's.  It's not an additional mod for current amps. 
 
The price of the 6EM7's + the adapters is $110... and... no other mods are required (already stock in the current amps).
 
Yes... the 6FD7 should be able to run stock in the current amps - but - not the older amps (which require the cathode cap upgrade to be safe). 
 
But... right now... I'm listening to the Sophia Electric 274B + Raytheon 6EW7's (big bottle, clear glass) and the combination sounds superb - as good as the Sylvania 6FD7's I think... maybe better. 
 
Try The Tube Store or Tube Depot, or Brent Jesse, or others - they may not list them in their ads.  Just email them all.
 

 

[Gradofan2]

Quote:

FWIW, there is one impression of this tube in the big Woo thread.  I recall the poster mentioned it's worth trying out but doesn't really qualify, why.

 
I assume, the poster had the older version of the amp, which did not have the upgraded cathode caps to safely handle the 6FD7's and 6EM7's. 

 

[grmnasasin0227]

Thanks for the replies guys. It seems to me by looking at the websites suggested that the brands you recommended are difficult to come by--hell it seems to even get a matched pair of 6EM7s or 6FD7s is very rare, the sites appear to sell them individually instead of matched...

 

[bobeau]

 
Quote:

I assume, the poster had the older version of the amp, which did not have the upgraded cathode caps to safely handle the 6FD7's and 6EM7's. 

Why?  Here's the post in question which was just last month, and he does actually give some feedback on the sound
 
http://www.head-fi.org/t/428570/woo-audio-amp-owner-unite/11475#post_7590756
 

 

[grmnasasin0227]

Can anybody else comment on where to buy tubes? I'm not having much luck in terms of finding places that sell matched pairs (or hell, even the manufacturers) of the tubes I want...even Ebay seems to be only selling individually.
 
I'm trying to find Sylvania/RCA/Raytheon 6EM7 or 6FD7 tubes, thanks much

 

[takezo]

Quote:

Can anybody else comment on where to buy tubes? I'm not having much luck in terms of finding places that sell matched pairs (or hell, even the manufacturers) of the tubes I want...even Ebay seems to be only selling individually.
 
I'm trying to find Sylvania/RCA/Raytheon 6EM7 or 6FD7 tubes, thanks much

if you're using the wa6, wa6se, wa22 or wa5 and wa5le, you don't need to have balanced or matched pair of tubes.
these amps auto-bias itself so matched pairs are not necessary. just don't put in a dead one or a shorting one.
 
i'm not certain but my older friends who know their tubes have told me that almost all of these dissimilar triode tubes
were made for t.v. sets during the 60's til the early 80's, and they were nearly all rebranded sylvanias or ge. brand
name doesn't matter so much with these tubes.

 

[grmnasasin0227]

Quote:

if you're using the wa6, wa6se, wa22 or wa5 and wa5le, you don't need to have balanced or matched pair of tubes.
these amps auto-bias itself so matched pairs are not necessary. just don't put in a dead one or a shorting one.
 
i'm not certain but my older friends who know their tubes have told me that almost all of these dissimilar triode tubes
were made for t.v. sets during the 60's til the early 80's, and they were nearly all rebranded sylvanias or ge. brand
name doesn't matter so much with these tubes.

Ah! Now we're on to something, thank you for shedding light on this, I greatly appreciate it! You've made my hunt much easier now.

 

[bobeau]

Quote:

The mod I'm referring to is likely an upgrade, which Jack made some time ago (he refers to the SN beginning the upgrade) - upsizing the cathode caps to handle the current or voltage draw of the 6FD7's.  It's not an additional mod for current amps. 
 

 
Reference?  On the Woo site for the 6SE he mentions
 
EM7: "NOTE: Serial number begins with 0410 is not compatible unless a modification is done. ".
 
6FD7: "6FD7 is a direct replacement for a 6DE7."
 
Edit:  never mind, it does appear in the big Woo thread that a change was indeed done around April 2010.  The Woo site should really clarify that.

 

[jhljhl]

Bump