[TruBrew]

thanks for the article. 

 

[jamato8]

Quote:

Quote:

I think it was said a couple pages back (can't keep the threads straight now) that since the Lyr was self-biasing, as long as the tubes were of the same type, everything should be good; I would imagine them being from the same manufacturer would also make a difference, but I'd think keeping both tubes of the same make (6922/6922, etc) would be the biggest thing.
 

Heres a good article explaining the misconception's of matched tubes

http://reviews.ebay.com/Buying-Matched-Tubes-6L6GC-EL34-5881_W0QQugidZ10000000007134035

The article is okay but is misleading also. The Hickok 439C is nice, and I have two of them, but a number of the Hickok testers are the same circuitry and do the same basic test, and a number of them for less money. Also the Hickoks don't test power tubes, the EL34's, 6550, Kt88 and so on, at working voltage. For the small tubes like the 6DJ8, 12AX7 and so on, they basically do. Also the life test can be done with most any tester by reducing the filament voltage to the next lower level. Of note is that many cheap testers apply voltage in such a way that they can do damage to a tube. This would be many of the cheap testers discussed in the article. 
 
Comparing the Siemens 6922 (silver shield, the later version compared to the earlier grey shield)  to the 6BZ7 now. 
 

 

[Jason Stoddard]

Transconductance matching is important on the Lyr, since it has a single voltage gain stage and no overall feedback. This means that if the tubes aren't closely matched, there may be gain differences between channels. We use a modern curve tracer that shows transconductance at our actual operating point.
 
This is the instrument we use: Longhin CT-01. It's a great machine, and even better if you happen to speak Italian (they're made in Italy.) http://www.audiopassword.com/tube_instruments.htm

 

[jamato8]

I am using the JH13's with the Lyr now. They just felt underpowered before. Just needed that extra bass Kick. So is there any hum, no not really. With no music there is a trace of sound but that means nothing since these are IEM's and the slight sound I hear isn't even apparent with the music playing and this amp obviously is meant for monitors requiring just a wee bit more power. It does work great to test for microphonic tubes though. :^) 
 
Oh and the sound? Pretty good. Plenty of detail and a sound quality that falls in line with the rest of the phones but I don't have quite the fast transient attacks as with the larger phones, could be the Seimens tubes so maybe I will try the 6BZ7's. 

 

[olor1n]

Quote:

Transconductance matching is important on the Lyr, since it has a single voltage gain stage and no overall feedback. This means that if the tubes aren't closely matched, there may be gain differences between channels. We use a modern curve tracer that shows transconductance at our actual operating point.
 
This is the instrument we use: Longhin CT-01. It's a great machine, and even better if you happen to speak Italian (they're made in Italy.) http://www.audiopassword.com/tube_instruments.htm

 
Thanks for the reply Jason. Any thoughts on Schiit sourcing the well regarded tubes and selling them through your site?
 
 

 

[MrScary]

The article is okay but is misleading also. The Hickok 439C is nice, and I have two of them, but a number of the Hickok testers are the same circuitry and do the same basic test, and a number of them for less money. Also the Hickoks don't test power tubes, the EL34's, 6550, Kt88 and so on, at working voltage. For the small tubes like the 6DJ8, 12AX7 and so on, they basically do. Also the life test can be done with most any tester by reducing the filament voltage to the next lower level. Of note is that many cheap testers apply voltage in such a way that they can do damage to a tube. This would be many of the cheap testers discussed in the article. 
 
Comparing the Siemens 6922 (silver shield, the later version compared to the earlier grey shield)  to the 6BZ7 now. 
 

Well I tried

 

[jamato8]

Quote:

Well I tried

Yes you did and a fine job you did! :^)
 

 

[MrScary]

I found some RCA Canada 6BZ7's on the ebay iltaly site hahaha I just hope they are really the canadian ones. Still waiting on my Valvo's and Seimens CCA's. I got my backup set of GE greyglass from ALO today and one of the tubes is bad
it has a screeching sound that remains when I change channels. Sucks, but they did give me the aluminum blocks for my LCD-2's which was cool of them. More steam punk look.. hahahaha

 

[dpump]

Jason,
 
My 1972 Sams Tube Substitution Handbook lists the 6ES8, 6FW8, and 6KN8 as replacements for the 6DJ8. Any thoughts as to whether it is ok to try any of these?

 

[Jason Stoddard]

Quote:

Jason,
 
My 1972 Sams Tube Substitution Handbook lists the 6ES8, 6FW8, and 6KN8 as replacements for the 6DJ8. Any thoughts as to whether it is ok to try any of these?

No experience with them--but if they're the same pinout they will plug in and bias up. 

 

[ZorgDK]

I'm looking at  6BZ7 tubes at ebay. Can anyone please help with a link to some that looks good. Maybe from a seller you think is reliable?

 

[MrScary]

I'm looking at  6BZ7 tubes at ebay. Can anyone please help with a link to some that looks good. Maybe from a seller you think is reliable?

The only one I saw for the RCA's is this one none of them have been tested but you get like 7 tubes so you should get a few good ones out of the lot. None of the RCA's have been tested that are on ebay at the moment for what the testing is worth

http://cgi.ebay.com/RCA-NOS-6BQ7A-6BZ7-6BS8-Tube-Lot-Vacuum-Radio-Vintage-7-/170643238244?pt=Vintage_Electronics_R2&hash=item27bb212d64

 

[maverickronin]

I've been following this thread but I don't really think I've seen anyone address this question.
 
Are there any tubes that turn the Lyr into a "wire with gain"?
 
I may be in the market for a wire with lots of gain soon and the Lyr seems to be offer the best bang for the buck.  I'm a little concerned about the tubes though.  I've already got some tube gear and the "flavor" it adds seems to be hit or miss for my tastes, great with some things and a disappointment with others.

 

[DemonicLemming]

I was actually pondering picking those up, but I went with these guys instead: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&rt=nc&nma=true&item=290565679624&si=i8X1HoAprjzmpUPv%252B0J6WOMoLuk%253D&viewitem=&sspagename=STRK%3AMEWNX%3AIT, http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&rt=nc&nma=true&item=290565678140&si=i8X1HoAprjzmpUPv%252B0J6WOMoLuk%253D&viewitem=&sspagename=STRK%3AMEWNX%3AIT, and http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=230618211125&ssPageName=STRK:MEWNX:IT.
 
Quote:

Quote:

I'm looking at  6BZ7 tubes at ebay. Can anyone please help with a link to some that looks good. Maybe from a seller you think is reliable?

The only one I saw for the RCA's is this one none of them have been tested but you get like 7 tubes so you should get a few good ones out of the lot. None of the RCA's have been tested that are on ebay at the moment for what the testing is worth

http://cgi.ebay.com/RCA-NOS-6BQ7A-6BZ7-6BS8-Tube-Lot-Vacuum-Radio-Vintage-7-/170643238244?pt=Vintage_Electronics_R2&hash=item27bb212d64

 

 

[MrScary]

I was actually pondering picking those up, but I went with these guys instead: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&rt=nc&nma=true&item=290565679624&si=i8X1HoAprjzmpUPv%252B0J6WOMoLuk%253D&viewitem=&sspagename=STRK%3AMEWNX%3AIT, http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&rt=nc&nma=true&item=290565678140&si=i8X1HoAprjzmpUPv%252B0J6WOMoLuk%253D&viewitem=&sspagename=STRK%3AMEWNX%3AIT, and http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=230618211125&ssPageName=STRK:MEWNX:IT.
 


 

Yeah I got the NOS tubes when I ordered I don't remember through whom now that ebay doesn't let you see the won list which is ridiculous.