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tube rolling for Woo WA6-SE

post #1 of 16
6/26/12 at 7:37pm
Thread Starter 

I've checked out a bunch of tubes for the Woo WA6-SE.

 

Mine is extensively modified so my results might not be typical, but I'm pretty sure they will apply to the stock amp (more or less).

 

The winner is an RCA 6DR7 I got from Jim McShane. It has good presence, dynamics, excitement, PRaT, and is not unflattering to less-than-perfect recordings.

 

I learned that with these old tubes, you must remove the oxidation from the pins to get anything like good performance.

 

Here are the tubes I tried:

  • 6FD7 I got from Woo. Not sure of the brand.
  • Two types of 6DR7: "Pinnacle" brand (Pinnacle is almost certainly relabeled from something else) from Woo, and RCA from Jim McShane.
  • Two types of 6EW7. Raytheon" purchased from Woo, and "Tung-Sol" purchased from Jim McShane.
  • Two types of 6DE7: an RCA brand from Jim McShane, and GE brand (I forget where I got that from)

 

Descriptions in order from bad to good:

  • Both 6EW7 were bad: not sure how to do describe it, but an unpleasant tonal balance. Resembles the sound of scraping glass. I know that doesn't make sense, but not sure how to describe it.
  • The GE 6DE7 had no dynamic impact. Crescendos couldn't bloom.
  • The RC 6DE7 was just very bland. No PRaT or excitement.
  • The 6FD7 might be to some peoples' taste. It's a lush tube and very flattering to all recordings. I ended up not liking it because there's no rhythmic excitement.
  • The Pinnacle 6DR7 is very good, extraordinary dynamics and PRaT, extraordinary microdynamic resolution, but not flattering to bad recordings. It has a very prominent upper midrange which can become "edgy" in a bad recording.
  • And the winner is the 6DR7. It has the good qualities of the Pinnacle 6DR7 but tones things down just enough to avoid that unflattering upper midrange.

 

I can imagine that some people would say the Pinnacle 6DR7 is the winner because it does have more rhythmic excitement and microdynamic resolution than the RCA 6DR7. For myself, I need to tone things down a bit, so I'll go with the RCA.

 

What is clear is that both 6DR7 are heads and shoulders above the others. I ordered two more brands of 6DR7 from Woo: Sylvania and Westinghouse. I'll report on those after they arrive and burn-in.

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post #2 of 16
6/26/12 at 7:50pm

In what way is your amp modified?  Would help us understand your impressions a lot better

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post #3 of 16
6/26/12 at 7:55pm
Thread Starter 
Quote:
Originally Posted by El_Doug View Post

In what way is your amp modified?  Would help us understand your impressions a lot better

I didn't do the modification myself, so I'm not sure what all was done. A guy named Igor Kuznetsoff (sole proprietor of the company K Works) did the mod -- his specialty is custom mods of all sorts of equipment.

 

I can say that he upgraded all internal wiring to Cardas Litz wire. He changed out capacitors in the power supply, added bypass caps, and added local power caps as close to the tubes as possible. He probably did a number of things to reduce problems caused by RF including the use of ERS paper.

 

Oh, I'm using the Sophia whats-it-called rectifier, the upgrade rectifier tube.

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post #4 of 16
6/27/12 at 5:26am
Interesting! I'm enjoying the Pinnacle 6DR7 now with the Sophia in my WA6 SE....it is my favorite combination of all of the tubes I purchased from Jack. I have started looking for other pairs of 6DR7's to try. I also have an EML 5U4G coming in and I have two of the USAF 596 rectifiers...just waiting on the adapter.
Edited by kev pfeifle - 6/27/12 at 5:28am
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post #5 of 16
7/6/12 at 6:36pm
Quote:
Originally Posted by mike1127 View Post

I've checked out a bunch of tubes for the Woo WA6-SE.

 

Mine is extensively modified so my results might not be typical, but I'm pretty sure they will apply to the stock amp (more or less).

 

The winner is an RCA 6DR7 I got from Jim McShane. It has good presence, dynamics, excitement, PRaT, and is not unflattering to less-than-perfect recordings.

 

I learned that with these old tubes, you must remove the oxidation from the pins to get anything like good performance.

 

Here are the tubes I tried:

  • 6FD7 I got from Woo. Not sure of the brand.
  • Two types of 6DR7: "Pinnacle" brand (Pinnacle is almost certainly relabeled from something else) from Woo, and RCA from Jim McShane.
  • Two types of 6EW7. Raytheon" purchased from Woo, and "Tung-Sol" purchased from Jim McShane.
  • Two types of 6DE7: an RCA brand from Jim McShane, and GE brand (I forget where I got that from)

 

Descriptions in order from bad to good:

  • Both 6EW7 were bad: not sure how to do describe it, but an unpleasant tonal balance. Resembles the sound of scraping glass. I know that doesn't make sense, but not sure how to describe it.
  • The GE 6DE7 had no dynamic impact. Crescendos couldn't bloom.
  • The RC 6DE7 was just very bland. No PRaT or excitement.
  • The 6FD7 might be to some peoples' taste. It's a lush tube and very flattering to all recordings. I ended up not liking it because there's no rhythmic excitement.
  • The Pinnacle 6DR7 is very good, extraordinary dynamics and PRaT, extraordinary microdynamic resolution, but not flattering to bad recordings. It has a very prominent upper midrange which can become "edgy" in a bad recording.
  • And the winner is the 6DR7. It has the good qualities of the Pinnacle 6DR7 but tones things down just enough to avoid that unflattering upper midrange.

 

I can imagine that some people would say the Pinnacle 6DR7 is the winner because it does have more rhythmic excitement and microdynamic resolution than the RCA 6DR7. For myself, I need to tone things down a bit, so I'll go with the RCA.

 

What is clear is that both 6DR7 are heads and shoulders above the others. I ordered two more brands of 6DR7 from Woo: Sylvania and Westinghouse. I'll report on those after they arrive and burn-in.

 

Curious where you got the Pinnacle 6DR7 haven't been able to find any online.. I don't have any DE7s, but have a couple 6EW7s which are ok, I wasn't crazy about the 6FD7s purchased from Woo because they introduced quite a bit of background noise (compared to the other tubes). Also currently using the Sophia Pricness and waiting on some adaptors to use my 596s - like Kev.


Edited by Ahzari - 7/6/12 at 6:38pm
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post #6 of 16
7/6/12 at 6:40pm
Thread Starter 

I got RCA 6DR7 from Jim McSchane. All the major NOS tube suppliers have them, you just have to ask. (Tube World, Tube Depot, etc.) The 6DR7 might not be listed on their website inventory list, because it's a less common tube.

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post #7 of 16
7/6/12 at 6:45pm
Quote:
Originally Posted by mike1127 View Post

I got RCA 6DR7 from Jim McSchane. All the major NOS tube suppliers have them, you just have to ask. (Tube World, Tube Depot, etc.) The 6DR7 might not be listed on their website inventory list, because it's a less common tube.

Thanks for the info.

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post #8 of 16
7/7/12 at 8:30pm
Quote:
Curious where you got the Pinnacle 6DR7 haven't been able to find any online

Ahzari:

 

Bought them directly from Jack and Woo Audio!

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post #9 of 16
7/9/12 at 7:06pm

Anybody try out any 6EM7 or 6DN7/6GL7 tubes? I just ordered a set of Drive/Power tube option 1: 1 matched pair of 6GL7/6EM7 plus one pair of 6GL7->6DE7 Teflon tube adapters, from Woo so i am interested to here peoples opinions on the tubes.

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post #10 of 16
7/9/12 at 10:30pm
Thread Starter 

I haven't 6EM7 or equivalent 8-pin tubes. Actually I mean I haven't tried them in the modded amp. When I first got my WA6-SE I ordered some of those 8-pin tubes, but they had a very different tonal balance than the 9 pins. They were very hot in the upper midrange. Absurd, really. (I returned them.) The 6DR7 was the most reasonable tube in the stock amp, and in the modded amp I still think it is the best of the 9-pin tubes.

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post #11 of 16
9/15/12 at 10:21pm

Hello...

I got some problems using RCA 6DR7.
Lots of noise and interference like a microphonic vibration or some else.
When I touch the tube a big noise goes to the headphones.

Can any help me about this issue?

 

Thanks

=)

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post #12 of 16
9/15/12 at 10:26pm
Thread Starter 

Some tubes are microphonic. You can get silicone high-temperature rings that work fine as tube dampeners from ebay for a few bucks each. Just search for "tube dampeners" or "tube dampers silicone"

 

You are protecting your tubes from all sources of vibration, including natural ground-borne vibration that is all around us even in tectonically inactive areas. Also protecting them from self-resonance.

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post #13 of 16
9/16/12 at 3:48am

yea I have a few tubes that are pretty microphonic as well - check out herbie's they have some great dampers; I've tried the Ultrasonic Rx and the Hal-O III, the Hal-O is a better damper but costs quite a bit more.. They have a awesome return policy so if you try them and don't find any benefit you can return them without a problem.

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post #14 of 16
9/16/12 at 2:46pm
Thread Starter 
Quote:
Originally Posted by Ahzari View Post

yea I have a few tubes that are pretty microphonic as well - check out herbie's they have some great dampers; I've tried the Ultrasonic Rx and the Hal-O III, the Hal-O is a better damper but costs quite a bit more.. They have a awesome return policy so if you try them and don't find any benefit you can return them without a problem.

And after you return them, buy some silicone rings for 50 cents each off Ebay. They worked better for me than Herbie's.

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post #15 of 16
9/16/12 at 5:04pm
Quote:
Originally Posted by mike1127 View Post

And after you return them, buy some silicone rings for 50 cents each off Ebay. They worked better for me than Herbie's.

did you try the Hal-O III's? they are in a different league than the Rx's.

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