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Promise not to tell? [message #9037]

Thu, 23 June 2005 14:49

BillEpstein
Messages: 886
Registered: May 2009

Illuminati (2nd Degree)

Really promise?
OK. GE 5 Star 5751's in the Norh SE-9 are the BOMB!
Shhh! We don't want E-Bayers running up the prices.

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Not nice to start rumors... [message #9038 is a reply to message #9037]

Thu, 23 June 2005 21:14

Triode_Kingdom
Messages: 13
Registered: May 2009

Chancellor

After giving the curves and specs a quick look, I believe this is another 12AX7 variant. They are already overvalued on eBay.

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Rumours, [message #9039 is a reply to message #9038]

Thu, 23 June 2005 22:29

Poindexter
Messages: 108
Registered: May 2009

Viscount

What do you know about 12BZ7's, my man? I got a bunch of these on a deal, because they have the same gain with twice the g and twice the gm of a 12AX; they looked like they could drive the RIAA from Hell.

I have heard that:
They are wildly variable in their characteristics, example-to-example (including in the same envelope),
They have a very short service lifetime, and then go hideously microphonic,
They tend to noise,
Other horrors.

Ever fool (I mean experiment) with any of these?

Y O S

Poinz

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Re: Rumours, [message #9040 is a reply to message #9039]

Fri, 24 June 2005 00:31

Triode_Kingdom
Messages: 13
Registered: May 2009

Chancellor

Sorry, never tried 'em. The plate curves don't seem to be as linear as the 'AX7, but that's minor compared to the possible flaws you listed.

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Re: Rumours, [message #9041 is a reply to message #9040]

Sat, 25 June 2005 19:35

Poindexter
Messages: 108
Registered: May 2009

Viscount

Pretty things, big ol plates. At a millivolt on the grid, we don' need no steenkin' linear. I was going to use them in the first stage of a phono amp, so I could put any nasty LCR RIAA in one lump, then maybe a 6922 SRPP output, minimize stages.

I don't have a turntable anyway, so they sit on the shelf.

Thanks,

Poinz

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Re: Promise not to tell? [message #9042 is a reply to message #9037]

Sat, 25 June 2005 22:40

metasonix
Messages: 103
Registered: May 2009

Viscount

If you gents had read my 12AX7 tests in VTV issues 1 and 14, you'd know that 5751s usually had lower distortion on average than 12AX7s or 7025s, in typical RC-coupled circuits. (Just a friendly reminder.)

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Re: OT: Care To Comment... [message #9043 is a reply to message #9042]

Sun, 26 June 2005 14:42

Brucie
Messages: 8
Registered: May 2009

Esquire

on your 811-10 amp discussion over on the Group Build Forum?

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Re: Promise not to tell? [message #9044 is a reply to message #9037]

Sun, 26 June 2005 19:47

GarMan
Messages: 960
Registered: May 2009

Illuminati (2nd Degree)

I've always had JAN 5751 in my headphone amp and sounds nicer than any 12AX7 I've tried. Listening to them right now.

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Re: OT: Care To Comment... [message #9045 is a reply to message #9043]

Mon, 27 June 2005 07:47

colinhester
Messages: 1349
Registered: May 2009
Location: NE Arkansas

Illuminati (3rd Degree)

Thanks, I was going to write Eric shortly and ask. The wife has been in Boston for the last week, and I've been Mr. Mom to 4 kids (all 5 and under.) BTW, I've got most of the parts on order, just need to nail down the resistors. I think I'm going going with 2W Kiwames across the board......Colin

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