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12av7 tubes

98.233.13.100
Posted on February 24, 2017 at 14:24:34
mpcrnc@aol.com
Audiophile

Posts: 92
Joined: July 3, 2002
 any recomendations for 12av7 tubes or some other substitute. This is for a berning zh 270. Thanks.

 

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RE: 12av7 tubes, posted on February 24, 2017 at 15:26:46
Jim McShane
Dealer

Posts: 5910
Location: Chicago
Joined: January 13, 2003
 Just be sure they are checked for microphonics! I'm trying to dig up some right now for a customer - and I've had 60+ out of 100 NOS GEs turn up microphonic. I wouldn't have believed it if it didn't happen to me!

BE SURE you get tubes tested for microphonics regardless of which brand.

 

RE: 12av7 tubes, posted on February 24, 2017 at 22:14:21
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 would some type of dampening make those usable?

 

RE: 12av7 tubes, posted on February 25, 2017 at 08:12:27
baileyler
Audiophile

Posts: 359
Location: Chadds Ford, PA
Joined: January 17, 2007
 There are variants with more substantial plate structure or even internal supports, like 6829, 6414 and some 5965.

They tend to be quite inexpensive, so it should be a good tube to do some trial and error with.

I can't comment on sound (incl. microphonics) because I don't use them (but have a box or two full of them laying around).

I wish I had a ZH270 to try them out with. :)

 

RE: 12av7 tubes, posted on February 25, 2017 at 08:19:05
Jim McShane
Dealer

Posts: 5910
Location: Chicago
Joined: January 13, 2003
 Good thought - but no, these are BAD! And the reason I say 60 or so are bad is I haven't tested the rest yet. I fully expect that all will be microphonic. None are even close to usable.

I got taken on this batch!

 

RE: 12av7 tubes, posted on February 25, 2017 at 08:45:45
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
 There are a lot of 12av7 types that were not designed for audio use. Many were used in analog computers. They can be good sounding and cheap to buy, but unfortunately you might need to test a few to get the ones that are good. I have tried some RCA and GE 5965 in my SE RH84 and 6L6 and as a driver/input tube they were ok. But perhaps in my use, not as critical as a preamp tube

 

RE: 12av7 tubes, posted on February 25, 2017 at 16:31:12
jyourison
Audiophile

Posts: 279
Location: Wisconsin
Joined: June 20, 2006
 At Jim McShane's suggestion I have subbed a 7062/E180CC for a 12AV7, and found it to work better in the application.

 

RE: 12av7 tubes, posted on February 27, 2017 at 11:56:42
Mechans
Audiophile

Posts: 1804
Location: East Coast
Joined: May 23, 2004
 I wonder if some tube circuits aren't just microphonic by design. Not intentionally of course just the nature of the beast!

 

Hmm...maybe thery're disguised 6C4s? (NT), posted on February 27, 2017 at 14:11:11
jeffreybehr
Audiophile

Posts: 5707
Location: Phoenix, Arizona
Joined: December 10, 2004
Contributor
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