[mikeymad]

I know that someone is using them on the WA5, but I don't know if I have heard someone using it with WA6 yet.

It is suppose to be a great rectifier, but more of a direct match with the 300B's

Cheers,

 

[jamato8]

Quote:

Originally Posted by jantze /img/forum/go_quote.gif Has anyone tried Sophia Princess Mesh Plate 274B? Woo Audio now recommends that tube as a replacement.

You can't use that in the 6 unless it is modified to have a cap of around 8uf as the first capacitor after the rectifier or you will stress the directly heated rectifier. The standard Woo 6 has too large a first cap for the Sophia and most any directly heated rectifier. I decreased mine but need to change things a little to be able to use the Mesh Plate but it would be a worth while adventure.

 

[jantze]

Quote:

Originally Posted by jamato8 /img/forum/go_quote.gif You can't use that in the 6 unless it is modified to have a cap of around 8uf as the first capacitor after the rectifier or you will stress the directly heated rectifier. The standard Woo 6 has too large a first cap for the Sophia and most any directly heated rectifier. I decreased mine but need to change things a little to be able to use the Mesh Plate but it would be a worth while adventure.

I did all the upgrades myself, so is Sophia Princess Mesh Plate 274B a no go now?

 

[takezo]

jamato has a valid point, but jack told me the wa-6 draws approx. 100 mA max.
from the rectifiers and i believe the mesh sophia can handle that type of
peak current... of course, i could be dead wrong and your mesh plate will die
within a week... you can ask jack directly, as he is very good at answering
these types of questions.

the solid plate sophias can handle up to 160 mA...

 

[atbglenn]

I asked Jack if I could use the Valve Art 274B in my WA6 and his response was:
"Glenn,

No problem. It is a direct drop-in for your WA6.

Jack"

Since he now offers the Sophia Mesh Plate 274B as an option for the WA6, I would think he knows best. At least I hope he does

P.S. I'm assuming the Valve Art and Sophia have similar specifications.

 

[jamato8]

Sophia recommends a max of 90mA's of current draw and a 4uf cap for the first capacitor after the rectifier. I spoke with them today. The rectifier life will be significantly shortened when you tax it. I thought the 6 was a little less than 90mA draw. I was going to modify using a 4uf cap to the first resistor but will measure the actual current draw of the amp first.

 

[jamato8]

Ok here is Jack's feelings on it. Because the voltage draw is much less than normal, as in a speaker amp, that even with a larger capacitor there is no problem and that the Sophia mesh plate 274B should work fine and they are using it and in the 6 as well.

 

[jantze]

Damn, now I must buy that tube

 

[atbglenn]

Quote:

Originally Posted by jantze /img/forum/go_quote.gif Damn, now I must buy that tube

I think I'm going buy one as well. I was originally going to get the Valve Art 274B for $14.99, but the only supplier that I know of (tubeman.com) told me he wouldn't have any till the end of the summer. Besides, the Sophia Mesh Plate looks so much cooler.

 

[musicmind]

Thanks for posting the follow up John, much appreciated.

 

[jamato8]

I am still researching. The manufacture and specs for the WE 274B says 8 or 10uf as max after the rectifier. I don't want to buy a 150 dollar rectifier just to have it blow after a few months.

 

[takezo]

okay, now you've perked my interest. where on this planet can you
find a WE274B for $150? let me know...please...
or were you referring to the sophia's princess 274B?

as a side note: i've been using the 5r4gy since early last year and
it has a recommended rating of 4 uF cap after the rectifier...
none of them has died yet... maybe the lower current draw of
the 6ew7 has spared them...

 

[jamato8]

Quote:

Originally Posted by takezo /img/forum/go_quote.gif okay, now you've perked my interest. where on this planet can you find a WE274B for $150? let me know...please... or were you referring to the sophia's princess 274B? as a side note: i've been using the 5r4gy since early last year and it has a recommended rating of 4 uF cap after the rectifier... none of them has died yet... maybe the lower current draw of the 6ew7 has spared them...

I meant the Sophia.

I don't know. I know that from experience that too high a cap can fry a rectifier and I have experienced this. If it is working than that is what counts. I don't get it though. It is just understood in power supply design and using a tube rectifier that you can unduly stress the tube. A directly heated rectifier comes up much fast, unlike a indirectly heated tube that comes up slowly. Now what Jack stated was that the circuit is a soft start. I have built power supplies with tube rectifiers but now I am just confused. I would prefer to not change my power supply and just use the Sophia mesh plate but I know what the specifications tell me and experience. 4uf is a long ways from 150uf or 200uf. If you have used the directly heated tube a lot since last year then what can I say? Try the Sophia mesh plate in the 6.

 

[takezo]

i was under the impression that the 5r4gy is an indirect heating
rectifier...

 

[jamato8]

Quote:

Originally Posted by takezo /img/forum/go_quote.gif i was under the impression that the 5r4gy is an indirect heating rectifier...

Ok. Too hard to mix my ICU work right now and this. Hard to shift back and forth sometimes.