Re: Hi Z Buffer Distortion

On Tue, 14 Apr 2009 05:26:21 GMT, "Paul Stamler" <pstamler@xxxxxxxxx>
wrote:

type 6AV6. Its triode is a half of
a 12AX7, probably the most linear device (into a suitably high
impedance, but also into a somewhat reactive load) that *can* be
made, and "NOS" devices shouldn't cost much of anything.

Naah; the 12AX7 isn't anything like the most linear tube out there. A 6SL7
can beat it, and so can a 5751, but if you want real clean behavior, a good
6SN7 or its relatives beats the crap out of any higher-mu tube.

I'll not argue too much - the last vacuum valve amplifier that
I built (in 1994) used 1/2 of a type 6SL7 driving paralleled sections
of a type 6SN7 driving a type 845, famous for its drive neediness
(over 300 volts peak-to-peak; yikes).

Good bottles of both these types are really, really good. My
favorites are the old Sylvania's with cylindrical cathodes, but
these days the hot tip is to use the 12 volt heater versions
(for availability!) or other un-hip voltages. And plain vanilla
Russians are surprisingly good - not much to go wrong with
these types really.

A good 12AX7/ECC83 is in this same ballpark, and IME more reliably
linear (into very high Z optimised loading, yada yada). "Good" here
means Telefunken's and large geometry Amperex's. Also the old
large geometry TungSol's and RCA's if sorted for noise are great.

There are lots of crappy, inexcusable 12AX7 type devices these
days - they are *not* 12AX7's - anything that looks Chinese is
probably a 12AT7 geometry (and worthless for linear audio).

Never seen a really linear 5751, but then I've sure not seen
everything! And they have an excellent rep.


Much thanks, as always,
Chris Hornbeck
.

Relevant Pages

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