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Dirty-South Blues Harp forum: wail on! > 12AV7 Tube? I'm holding it, so...
12AV7 Tube? I'm holding it, so...
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Mensh
49 posts
Oct 01, 2016
6:41 PM
... I know it's real.

I came into possession of a Sylvania NOS 12AV7. Yes, it's V. I've been doing the harp-thing since I was twelve and I have never heard of these. Why?
After some sleuthing, I see it's comparable in strength to an AY7, and somewhat near a 5751.

What can I expect if I put this into my '65 Kalamazoo Model II?
Thanks, all.
Heath
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www.thebluesprofessors.com

Last Edited by Mensh on Oct 01, 2016 6:41 PM
Bass410man
96 posts
Oct 01, 2016
7:41 PM
Well you can expect the tremolo to stop working, it needs a X7 to work. I had one, and I experimented with different tubes, but found the X7's to sound the best.
Greg Heumann
3278 posts
Oct 03, 2016
8:46 AM
Bass410Man beat me to it, but he is correct. The Kalamazoo only has 1 tube in its preamp so it really isn't overly gainy but I have tried other tubes in that position. Anything other than a 12AX7 will kill the tremelo, but more importantly just really isn't necessary. For the record, here are the 12A?7 series tubes and their gain factors:

GAIN FACTOR 100: 12AX7 - aka ECC83, 7025, ECC803, E83CC, 6681
GAIN FACTOR 70: 5751
GAIN FACTOR 60: 12AT7 - aka ECC81, 6201, 6679, 6829
GAIN FACTOR 45: 12AY7 - aka 6072, 6211
GAIN FACTOR 41: 12AV7 - aka 5965
GAIN FACTOR 19: 12AU7 - aka ECC82, 5963, 5814, 6189


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/Greg

BlowsMeAway Productions
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Mensh
51 posts
Oct 03, 2016
12:14 PM
Thanks Gentlemen -

Greg, I know that the AY gets a bad rap. Is the AV similar?

Heath
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www.thebluesprofessors.com
Greg Heumann
3280 posts
Oct 05, 2016
10:01 AM
The AY doesn't get a bad rep from me. Sometimes it is the right tube for the job. If you own a Harp Train 10, for example, I think it is a great choice.

As to "Y" vs "V" - you'll need someone with more tube knowledge than me to explain why there would be two models so close in gain. I suspect there is something ELSE different between them but 12AV's are pretty rare so I don't have any personal experience to lean on.
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/Greg

BlowsMeAway Productions
See my Customer Mics album on Facebook
Bluestate on iTunes
barbequebob
3295 posts
Oct 05, 2016
10:34 AM
The 12AY7 is one of the differences on why a real 59 Bassman sounds far different than the reissues do and that's the very first preamp tube in a real one and the Fender reissues uses a 12AX7, which makes the amp more gainy and trebly. My guess about the 12V7 may lie in the design of the filament and I don't recall ever seeing one of these are used in instrument amplifiers at all and may be better suited to things like old tube stereo system preamps or for communication purposes only.
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Barbeque Bob Maglinte
Boston, MA
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SuperBee
4168 posts
Oct 05, 2016
6:29 PM
Maybe the ay gets a bad rap specific to its use in a zoo? I dunno, certainly they are well-thought of in plenty of other amps and were original equipment in a bunch of the fender tweeds.
These AV tubes are different in more ways than just the gain factor.
They were used in radios and TVs. Not so much in audio amplifiers. Have more in common with 12AT7, but heaters have higher current draw.
Whether they're any good in a particular circuit kind of depends on a bunch of other considerations but generally not highly thought of as a preamp tube. Everything I can find suggests the most likely application is as a phase inverter but that's n/a for a 'zoo.
1847
3735 posts
Oct 05, 2016
8:00 PM
pretty sure that was a typo,,, the at gets the bad rap ..not the ay
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Mensh
52 posts
Oct 06, 2016
3:40 AM
Yes! I was a typo!
(actually, a mental typo - I forgot that it's the AT that gets the rap)
I will throw the 12AV7 into my VHT and report back*.

*remind me: when swapping tubes, do I need to worry about electrocution? I may not be ready to die.
Heath
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www.thebluesprofessors.com


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