[Xcalibur255]

I've always been a little weary of tubes with grid caps in general for precisely this reason.

 

[Oskari]

That title does not belong to that auction item. The 6N5S is a 6AS7G but that is not a 6N5S we see.

 

[Csericks]

Please excuse my lack of experience. I've owned various tube amps during the past dozen or so years but the past month or so with my WA 2 is my introduction to an amp using variants of the 6as7.  I have just acquired a pair of NOS JAN RCA 6as7g Black Plates from a reputable dealer.  There is a rather prominent hum with these tubes.  Is this a common problem with these tubes? 

 

[hodgjy]

Yes, the tubes can be quite noisy for up to 30 hours.  Then, they usually settle down.  However, I've noticed that most of the RCA 6AS7G tubes I put into my WA3 (similar design as the WA2) always seem to hum.  I can't figure out if I'm just unlucky with every RCA I've tried, my WA3 is defective, or if it's a design issue inherent with Woo OTL amps.
 
Quote:

Please excuse my lack of experience. I've owned various tube amps during the past dozen or so years but the past month or so with my WA 2 is my introduction to an amp using variants of the 6as7.  I have just acquired a pair of NOS JAN RCA 6as7g Black Plates from a reputable dealer.  There is a rather prominent hum with these tubes.  Is this a common problem with these tubes? 

 

 

[Csericks]

So after a few extended sessions they should calm down?  Is this a problem that is limited to RCAs?

 

[hodgjy]

Many tubes need to "burn in" before they become stable.  It's common for tubes to hum, buzz, howl, pop, etc. for up to 30 hours or so while they burn in.  This is universal to many makes and brands of tubes.
 
Quote:

So after a few extended sessions they should calm down?  Is this a problem that is limited to RCAs?

 

 

[Csericks]

I have experienced no such issues with my WA 6 or my ARC gear.

 

[hodgjy]

Is your WA2 your first OTL amp?  OTL amps are more colored by tubes, and therefore, are more prone to their flaws.

 

[Csericks]

This is my first OTL.

 

[hodgjy]

In general, the 6AS7G family of tubes are some of the noisiest tubes out there.  Then, throw them into an OTL amp as the power tube, you are prone to a lot of noise.  The WA6 uses an output transformer, so it's a less noisy design to start.  OTL amps tend to sound the most "tubey" and euphonic, but they are also more prone to tube noise than their transformer-coupled cousins, in my opinion.

 

[2359glenn]

 
Quote:

In general, the 6AS7G family of tubes are some of the noisiest tubes out there.  Then, throw them into an OTL amp as the power tube, you are prone to a lot of noise.  The WA6 uses an output transformer, so it's a less noisy design to start.  OTL amps tend to sound the most "tubey" and euphonic, but they are also more prone to tube noise than their transformer-coupled cousins, in my opinion.

A  OTL amp takes the output right off the tube but a amp with a output transformer the tube puts out a higher audio voltage and that voltage is dropped by the ratio
of the transformer. So the noise is dropped by that ratio of the transformer. Plus the WA6 uses a tube that is not as noisy as a 6AS7.
    If you want 6AS7s that aren't noisy try Russian 6AS7/ 6H13 they are very cheep direct from Russia and don't sound that bad..

 
 

 

[Xcalibur255]

Quote:

So after a few extended sessions they should calm down?  Is this a problem that is limited to RCAs?

You can find quiet RCAs, but it can take some patience.  I think the TungSol/Chatham version of this tube is quite a bit better all around, but they are very hard to find these days.

 

[john57]

Quote:

You can find quiet RCAs, but it can take some patience.  I think the TungSol/Chatham version of this tube is quite a bit better all around, but they are very hard to find these days.

 
It is a bit of a issue to find good 6AS7's RCA out there. I just put in a pair of Chatham 6AS7 tubes in my amp. I just worn out my first pair ofTungSol 6080 tubes. I agree that the TungSol/Chatham tubes are quite good.

 

[hodgjy]

I've used the Russian tube before.  It's nice, and I think it's quite underrated around here.
 
Quote:

 
    If you want 6AS7s that aren't noisy try Russian 6AS7/ 6H13 they are very cheep direct from Russia and don't sound that bad..

 
 

 

 

[Xcalibur255]

Quote:

 
It is a bit of a issue to find good 6AS7's RCA out there. I just put in a pair of Chatham 6AS7 tubes in my amp. I just worn out my first pair ofTungSol 6080 tubes. I agree that the TungSol/Chatham tubes are quite good.

You wore a pair of 6080 out already john?  You must leave your amp on most of the time.