[Torero]

With this adapter (6SN7 --> 6FQ7/6CG7):

Adapter ECC32 6SN7 TO 6CG7 tubes SUB - eBay (item 250353492204 end time Feb-05-09 18:08:58 PST)

and takezo adapter (6FQ7/6CG7 --> 6DE7)


Is it possible to use the 6SN7GT ? Is it compatible?

Excuse my ignorance.

 

[paara]

Quote:

Originally Posted by Torero /img/forum/go_quote.gif Is it possible to use the 6SN7GT ? Is it compatible?

Quote:

Originally Posted by Mail from Jack at Woo audio ....The 6SN7 is a driver tube which cannot be used on the WA6's design....

So there you have it

 

[takezo]

yes, one can use the 6sn7 tube on the wa6 and wa6SE... with
heavy pin layout modifications. you can use the adapter in the pic
but you'd need to take it apart and rearrange the pin connections.

left layout is the 6de7 and the right is the 6sn7

 

[paara]

Quote:

Originally Posted by takezo /img/forum/go_quote.gif yes, one can use the 6sn7 tube on the wa6 and wa6SE... with heavy pin layout modifications. you can use the adapter in the pic but you'd need to take it apart and rearrange the pin connections. left layout is the 6de7 and the right is the 6sn7

When I mailed Woo audio about modifying the WA6 to use the 6sn7 tubes, he said that it could not be done. It could be done on the WA3/3+ and WA2, but not WA6

But I guess everything is possible, it just depend on how much you are willing to change.

 

[WalkGood]

Orcin, Nice review and a pleasant read, I couldn’t agree more with you on the Sophia Princess Rectifier ^_^

 

[jamato8]

It wouldn't be my first choice for a few reasons but if the 6FQ7 is being used, then electrically, if wired correctly but not with the adapter above, it will work.

 

[takezo]

Quote:

Originally Posted by paara /img/forum/go_quote.gif When I mailed Woo audio about modifying the WA6 to use the 6sn7 tubes, he said that it could not be done. It could be done on the WA3/3+ and WA2, but not WA6 But I guess everything is possible, it just depend on how much you are willing to change.

electrically there doesn't seem to be any problems. both operate at 6.3v and
the 6de7 draws .9A, whereas the 6sn7 draws .6A. maximum plate voltage tolerable
is 275v and 300v respectively; both are within specs of the wa6/wa6SE.
as you can see, every pin of the eight on the 6sn7 differs from the arrangement
of the 6de7... which means one will have to re-arrange each of the eight from
the octal type of the 6sn7 to a 9-pin socket layout. it's time consuming and
may not be worth doing since the 6FQ7 and 6CG7 are small bottle versions of
the 6sn7. (the adapter for the 6FQ7/6CG7 is much easier, as only one pin is
arranged differently) but if you already have a great collection of 6sn7 and want
to see how they sound thru the wa6/wa6SE it may be a fun project. finding
a housing which will accomodate the larger octal socket and the smaller 9-pin
socket may be time-consuming too. using plumbing pvc or copper reducing
couplings may do the job... or get the adapter in the pic at top and take it
apart to rearrange the pin connections to go from 6sn7 to 6de7.

 

[jamato8]

I used to make adapters to go from different 9 pin tube to octals etc. It takes a little while and once you get it down you can make some very nice looking adapters but I think there would be some better choices for the power requirements than the 6SN7.

 

[takezo]

hi john, is there any other that you'd recommend over the 6sn7?
if it sounds anything like the 6fq7, i'd be pleased. very smooth and
open sound... though not dynamic like the 6de7 or the 6cy7.

 

[paara]

Quote:

Originally Posted by takezo /img/forum/go_quote.gif electrically there doesn't seem to be any problems. both operate at 6.3v and the 6de7 draws .9A, whereas the 6sn7 draws .6A. maximum plate voltage tolerable is 275v and 300v respectively; both are within specs of the wa6/wa6SE. as you can see, every pin of the eight on the 6sn7 differs from the arrangement of the 6de7... which means one will have to re-arrange each of the eight from the octal type of the 6sn7 to a 9-pin socket layout. it's time consuming and may not be worth doing since the 6FQ7 and 6CG7 are small bottle versions of the 6sn7. (the adapter for the 6FQ7/6CG7 is much easier, as only one pin is arranged differently) but if you already have a great collection of 6sn7 and want to see how they sound thru the wa6/wa6SE it may be a fun project. finding a housing which will accomodate the larger octal socket and the smaller 9-pin socket may be time-consuming too. using plumbing pvc or copper reducing couplings may do the job... or get the adapter in the pic at top and take it apart to rearrange the pin connections to go from 6sn7 to 6de7.

Thank you for that reply

very helpful

 

[jamato8]

Quote:

Originally Posted by takezo /img/forum/go_quote.gif hi john, is there any other that you'd recommend over the 6sn7? if it sounds anything like the 6fq7, i'd be pleased. very smooth and open sound... though not dynamic like the 6de7 or the 6cy7.

It won't be dynamic because you are getting a mismatch on the impedance of the tube. The 6DE7 has the output section with a different output impedance and the output transformers are designed for that. The 6DE7 is also going to put out more power, which is what you are hearing.

I haven't investigated at all. Since there were so many thousands of different types of tubes made I wouldn't be surprised if there aren't more but as time goes by, more and more of the less than desirable tubes, due to little use, are being used for landfill, so they are hard to find.

Frankly I would do more in playing with the voltages than more tubes. I would run the 6DE7 harder, though it wouldn't last as long, I bet it might sound even better. It is run at some pretty low voltages but the transformer in the 6's only put out 200 to 230 or so in the SE. Now it might be interesting to go ahead and raise the voltage on the first section but then you have to be concerned with the plate resistance and having two low a a resistance in the dropping resistor so that is where having more voltage to begin with really helps, you can still use a 68K and maybe have 130 volts on that first section rather than 65 or so. It would increase the dynamics, both macro and micro. There are some other things I would do and I thought about just dropping another transformer into the 6 but no real time.

 

[takezo]

Quote:

Originally Posted by jamato8 /img/forum/go_quote.gif It won't be dynamic because you are getting a mismatch on the impedance of the tube. The 6DE7 has the output section with a different output impedance and the output transformers are designed for that. The 6DE7 is also going to put out more power, which is what you are hearing. I haven't investigated at all. Since there were so many thousands of different types of tubes made I wouldn't be surprised if there aren't more but as time goes by, more and more of the less than desirable tubes, due to little use, are being used for landfill, so they are hard to find. Frankly I would do more in playing with the voltages than more tubes. I would run the 6DE7 harder, though it wouldn't last as long, I bet it might sound even better. It is run at some pretty low voltages but the transformer in the 6's only put out 200 to 230 or so in the SE. Now it might be interesting to go ahead and raise the voltage on the first section but then you have to be concerned with the plate resistance and having two low a a resistance in the dropping resistor so that is where having more voltage to begin with really helps, you can still use a 68K and maybe have 130 volts on that first section rather than 65 or so. It would increase the dynamics, both macro and micro. There are some other things I would do and I thought about just dropping another transformer into the 6 but no real time.

the impedance mismatch doesn't seem to affect the openness and soundstage
of the 6fq7... the left to right soundstage seems larger than the 6de7...
there's better clarity of the sound too, leading to a very open sound. while
the 6de7 seems to have a u-shaped freq. characteristics, the 6fq7 has a
more linear characteristics...less dynamic but everything just sounds right.
i can see how this may sound boring and flat, but with classical and acoustic
jazz it really brings out the nuance of timbre and texture, as well as a larger
soundstage.

it would be interesting to pop in a toroidal power transformer rated at 300va
but it'd be leading to a bigger job than experimenting with simple adapters
and tubes... for now...

 

[jamato8]

Quote:

Originally Posted by takezo /img/forum/go_quote.gif the impedance mismatch doesn't seem to affect the openness and soundstage of the 6fq7... the left to right soundstage seems larger than the 6de7... there's better clarity of the sound too, leading to a very open sound. while the 6de7 seems to have a u-shaped freq. characteristics, the 6fq7 has a more linear characteristics...less dynamic but everything just sounds right. i can see how this may sound boring and flat, but with classical and acoustic jazz it really brings out the nuance of timbre and texture, as well as a larger soundstage. it would be interesting to pop in a toroidal power transformer rated at 300va but it'd be leading to a bigger job than experimenting with simple adapters and tubes... for now...

Great, I am glad to read that the tube sounds fine. That is what it is all about. If it sounds that good then it would be fun to try some nice 6SN7's like the '52 Sylvania or a nice 1940's black glass Tung-sol. Well there are many. And then there are the loctals.

 

[Gradofan2]

Quote:

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

Finally, got to try the RCA Fat Bottle 6FD7 tubes in my SE Maxed with my Philco 5U4GB, at the moment.

My first impressions are consistent with what some of you have reported... they seem to be a bit of a cross between the 6DE7s and 6EW7s - with exceptional bass and treble extension, and pretty good PRAT and impact, though not to the extent of the 6DE7s (especially the Tung Sols). They seem to have a bit greater detail and texture, expecially in the bass. The mids are a bit less prominent and rich, and the upper mids and highs seem a bit more emphasized relative to the lower mids.

The soundstage is far more airy with greater ambience than the 6DE7s, more like the 6EW7s, but even greater - almost to the extent of being too emphasized, and almost artificial like the reverb, and ambience produced by a sound processor. This may be fine for classical music in halls, and larger venues... but... it may be a bit excessive for more intimate venues like jazz clubs, etc. I think I prefer the richer, bolder sounds of the Tung Sol 6DE7s and similar tubes, for jazz clubs, R&B, and intimate vocals.

But... if you like a big, open, airy, more diffuse sound, you'll like the RCA 6FD7s.

Of course, as previously noted, they have about 10-15% more "practical gain" (9 O'clock vs 10-11 O'clock for the same volume), though their MU is much greater... but... don't seem to have a any noticeable noise at reasonable volume levels.

I still think I prefer the 6DE7s for the music I listen to most - to the 6FD7s, or 6EW7s, which both seem to be much more airy and diffuse.

But... we'll see...

 

[Gradofan2]

Also... I've got a question...

The RCA 6FD7 Fat Bottle tubes have rather short pins, the combo of which allows the tubes to contact the socket mounting screw tips, preventing the from seating very securely in the sockets. I have not had this issue with the fat bottle 6EW7s - possibly their pins are longer, allowing the to seat better.

What's the best way to resolve this issue?

Should I grind off the screw tips a bit, or should I have Jack send me some replacement screws, which do not extend as far (or, possibly try to find some at a hardware store? Has anyone any experience with resolving this issue?

I'm a bit concerned about grinding off the screw tips that I might get metal particles caught in the sockets, or circuits in some manner causing a short. Though, I guess I could protect the sockets with tape, and brush / vacuum the amp well.

Any thoughts?