[takezo]

Quote:

Originally Posted by atbglenn /img/forum/go_quote.gif I don't think it matters if they're matched or not. As long as they are the same brand, from the same vintage. I bought 4 RCA 6DE7's from tubedepot.com awhile back and I highly doubt if they are matched. I cant detect any imbalance whatsoever.

the pair doesn't have to be matched very closely, but i have found some
volume discrepancy between pairs with more than 20% difference in
transconductance using the tv7 d/u. for example 75/48 and 56/36 for a 6de7.
(using a bias probe and multimeter is much more exact since you'd be getting
reading at the amp's operating voltage...) the volume difference wasn't very
great but it is noticeable and can be somewhat annoying.

 

[atbglenn]

Quote:

Originally Posted by takezo /img/forum/go_quote.gif the pair doesn't have to be matched very closely, but i have found some volume discrepancy between pairs with more than 20% difference in transconductance using the tv7 d/u. for example 75/48 and 56/36 for a 6de7. (using a bias probe and multimeter is much more exact since you'd be getting reading at the amp's operating voltage...) the volume difference wasn't very great but it is noticeable and can be somewhat annoying.

I haven't noticed any imbalance the pairs that I own. I guess I got lucky, or my hearing is not as sensitive as yours in that respect.

 

[tin man]

This has been a very informative thread. Thanks to everyone for educating me about the two Woo6 amps and all of the possibilities.

A couple of questions if I may. How long is the umbilical cable from the PS rectifier unit to the 6EW7 unit? And does it help to physically separate the two sections, or can they sit side by side without any difference in noise/hum from the large power supply unit?

Thanks again for such an inspiring thread. Maybe if I get a tax refund this year . . . . . .

 

[sclamb]

The umbilical is about 8 or 9 inches long so the units have to sit side by side.

 

[tin man]

Thank you sclamb!

 

[AntiGeek]

Some quick, dusty snaps. Not used my camera for a while so I decided to test to see if still working.

Rear shot shows second inputs and switch removed from mine for cleaner signal path (by Jack Wu on my request).

The serial number is : S1108025. I assume this is numbered after its order or completion date 25/11/08??

 

[tin man]

Very nice AntiGeek.

This thread is killing me . . . . must . . . . . refrain . . . . . . from spending . . . . . .

 

[Torero]

My initial impressions with the RCA fat bottle 6FD7 are:

- Better soundstage.
- Much better instrument separation and air.

I like!!

 

[AntiGeek]

Quote:

Originally Posted by tin man /img/forum/go_quote.gif Very nice AntiGeek. This thread is killing me . . . . must . . . . . refrain . . . . . . from spending . . . . . .

Resistance is futile!!

Sounds even better than it looks..

 

[AntiGeek]

Quote:

Originally Posted by Torero /img/forum/go_quote.gif My initial impressions with the RCA fat bottle 6FD7 are: - Better soundstage. - Much better instrument separation and air. I like!!

What tubes were you using before the RCA 6FD7s?

I Also have some of these RCA fat bottle 6FD7 tubes.

Not yet tried them, though the thin RCA version does sound very good. Too much gain with the k701s through the 6se though. Perhaps the power output is slightly higher through the SE.

 

[Torero]

Quote:

Originally Posted by AntiGeek /img/forum/go_quote.gif What tubes were you using before the RCA 6FD7s?

Before the 6fd7 i had used these tubes:

RCA 6DE7
RCA fat bottle 6EW7
SYLVANIA fat bottle 6EW7
GE clear-top 6EW7
RCA thin bottle 6EW7

IMHO, the best are GE and RCA thin bottle 6EW7's.

Now, the RCA 6fd7 are still burning. But my first impresions are very positive.

Coming soon: the GE clear-top 6FD7

 

[AntiGeek]

Yeah, the GE 6EW7's are excellent tubes and seem to match the K701s perfectly. What I like most is the excellent treble / mids. On the start of almost any track of any CD recording, I can hear the background recording hiss (any anything else going on!!) prior to music starting. Really noticeble in recordings such as Nirvana "Unplugged in New York", one of my favourate "reference" recordings.

Another positive of these tubes is the deep 3d headstage. Makes excellently produced / engineered albums like Roger Waters "Amused to death" sound almost scary..

 

[Raylinds]

A very well written and thoughtful review and an interesting thread. Thanks everyone for the great info.

 

[Orcin]

Thank you, Raylinds! A lot of people have contributed information to this thread, and it has become a great resource about these amps.

I am still very happy with my amp. I am thinking a lot lately about how nicely it could drive a pair of high-end phones. Say maybe... HD800's for example.

 

[atbglenn]

I have mine since last May, and I'm still in love with it. Great Amp!