Michael Dunn <mdunn@...>
Just a note to those who may have some 12AX7s in their equipment (e.g., 549 has 2) or junk box:
Check your stuff for Telefunken tubes. There are some strange people out there who pay big bucks for them (on eBay for example). Also, take a look at the tube's plates. If they're smooth (without any corrugations), they're even MORE valuable. I've recently seen (used) smooth ones go for U$25-30 each, and ridged ones for U$15-20 ea! NOS (unused) would presumably fetch even more.
Altogether, I've found six smooth ones in my junk and 549! Replaced the 2 in the 549 with some *non*-valuable ax7s I had, and, big surprise, it works just as well ;-)
p.s., I just sold mine for U$51, $68, and $123 a pair!!!!! I can only guess that the $123 pair went for so much because of the good condition of the labelling on it! Yet, the other two pairs went in inverse proportion to legend quality. Crazy audio nuts...
Michael Dunn | Surround Sound Decoder & Stereo Enhancer
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Phil (VA3UX) <phil@...>
The vacuum tube audio guys have gone absolutely "stupid" over this sort of thing. This is the same group that will pay $100 per foot for special oxygen-free speaker cable, $50 for special medical grade 120V wall receptacles, $75 for a bloody "rock" that sits on top of their amplifier to stop electromagnetic radiation from "interfering with the music flow in their cables" (that one is called a Shakti Stone - it should be Shaft-ye Stone). You or I will pay 50 cents or a buck for good quality cap for use in an RF circuit - these guys have been duped into paying 5 and 10 bucks for the same thing because the cap has special musical qualities.toggle quoted messageShow quoted text
I agree that you can make some pretty good money from these guys by selling Tek quality tubes (Telefunkens especially, but also Philips and Mullards too). Bear in mind that you'll be competing with this same crowd when you discover that you need a good quality 12AX7 to make something work well, and that you previously sold all yours to them. I'd hang-on to a few.
Having said all that - I admit that I sold a pair of used VT-52's (military type 45's) for $300 US - $450 Canadian - to the audio guys on eBay. The VT-52's were in a large box containing 500 used tubes and I paid $15 for the whole box. I'm ashamed - but happy.
At 08:35 PM 6/14/2001 -0400, you wrote:
Just a note to those who may have some 12AX7s in their equipment
Ahhh, a topic that I'm well versed in. I'm an "audio nut", but am totally not into $100 cable, stones, magic dots, etc. I'm into the DIY tubes and speakers end of it. While there IS a lot of hype, bullsh*t, and stupidity in high end audio, there is also a lot of truth.
Capacitors, wire, resistors, tubes, transformers, ALL of it makes a difference beyond what one can measure with a scope or distortion meter. I am a skeptic, but personally witnessed the differences between half a dozen .1uF/630V coupling caps in an amp. It is subtle, but there. Ditto for tubes and wire. Speaker cables have a lot more going on than just resistance per foot. There are interactions between the wire strands, the insulation, the braid geometry (if any). Inductance and capacitance come into play and how that interacts with the output impedance of the amp.
However, I STILL won't pay these ridiculous sums for stuff making seemingly amazing claims. My speaker cable is made from CAT 5 network cable, costing me a total of $40 for the pair. They smoke some $250 cables I had (I didn't pay that for them).
Anyway, regarding Telefunken. Telefunken tubes command a high price simply because they were the finest quality tubes produced by anyone, ever. Truly the Mercedes of the tube world. Tele 12AX7's were the quietest, lowest distortion, and longest lasting tube out there (100,000 hours is a typical lifetime). I've got several pairs of smoothplates (borrowed out of my Tek 535A) and some from an old Dynaco amp, and they do indeed sound very nice. I've compared them with current production JJ/Tesla 12AX7's and find them better, but not enough to spend $100 each. I'll use the JJ's at $7 each and be happy.
I get the biggest kick out of homebrew audio by building something that uses a forgotten $5 tube (the 1625) that will smoke most commercial gear costing 10x as much.
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In a message dated 06/15/2001 8:43:03 AM Eastern Daylight Time,
1uF/630V coupling caps in an amp. It is subtle, but there. Ditto fortubes
and wire. Speaker cables have a lot more going on than just resistance perI have never read about this in the electronics literature, but look up the
phenomenon of "superwaves" in the field of oceanography. In perfectly normal
weather, the random energy of the ocean wave trains can suddenly all add up
in phase generating a superwave that can engulf ships and islands without
In audio, with tens of thousands of waves per second, the same phenomenon can
occur. The input transducer (microphone or magnetic pickup) will filter this
out initially, but random phase shifts within the electronics can re-phase
the waves to produce instantaneous voltage or current amplitudes far above
the average at the input. How this sounds depends entirely on how the
electronics handles instantaneous overloads. Tube circuits and analog
magnetic recorders are much kinder to these transients than are solid state
or digital systems.
My theory is that a lot of the subjective advantage of tube and analog sound
is based on this. Extremely linear phase response throughout the system will
prevent audio superwaves from developing within a system, and this would
explain the perceived advantages of precision capacitors, coils and
Excuse my ignorance, but what is so special about the 12AX7s compared totoggle quoted messageShow quoted text
any of the other twin triodes?. I have been swaping them around for years
in various pieces of equipment without much problems. I have several in
their original boxes too, how much more valuable that makes them?.
Things seem to be getting out of control these days.
Joe Orgnero VE7LBI CCA 96-418
From: Michael Dunn <firstname.lastname@example.org>
To: TekScopes@yahoogroups.com <TekScopes@yahoogroups.com>
Date: June 14, 2001 5:39 PM
Subject: [TekScopes] Valuable 12AX7!
Just a note to those who may have some 12AX7s in their equipment