Topics

Valuable 12AX7 and all this audio foo foo.


dhuster@...
 

Methinks the tops of my boots are needing a few more inches to clear
the effluent which is building.

Ain't no way the human sense of hearing has the bandwidth or the
dynamic range that even modest test equipment has. There is not a
doubt in my mind that I could write up a page of pure fiction
(including some references to Atlantis and perturbences in the orbit
of Io) and be able to sell my own homemade capacitors (I think that
Saran wrap and aluminum foil will do nicely) and homemade speaker
wire (I think that braiding some Solder Wick with spark plug wire may
do the trick) and sell these items for fantastic amounts of money to
Golden-Eared audio enthusiasts. Easily. It wouldn't be honest, but
sometimes when I read all the ads, it appears that this crowd doesn't
want honesty.

Audio is so darned subjective that no one person can say what's
right. More of my opinion (and that's exactly what it is) should be
showing up in the October 2001 installment of "Q & A"
in "Poptronics". I'll gladly put my 12AX7's on the block. Lessee,
here's the ad copy:

"Specially burned in for smooth audio quality without the sharp edges
one experiences with all new tubes. The lettering on the glass has
been removed to improve the transparency of the sound. Tubes with
specially-rounded exhaust nipples available upon special order."

Dean


Stan or Patricia Griffiths <w7ni@...>
 

I am with Dean on this one. There is a special process called "double-blind
testing" where these sorts of claims can be debunked. If I understand it
right, double-blind testing amounts to the listener not knowing what
configuration he is listening to and being required to choose between "A" and
"B" a LOT of times, enough to get a pretty good statistical picture of
whether things like tube brands, oxygen free speaker wire, and precision
capacitors REALLY make a difference you can hear. Most audio nuts that I
know REFUSE to submit to double-blind tests . . . and I think we ALL know why
. . .

Stan
w7ni@easystreet.com

dhuster@pb.k12.mo.us wrote:

Methinks the tops of my boots are needing a few more inches to clear
the effluent which is building.

Ain't no way the human sense of hearing has the bandwidth or the
dynamic range that even modest test equipment has. There is not a
doubt in my mind that I could write up a page of pure fiction
(including some references to Atlantis and perturbences in the orbit
of Io) and be able to sell my own homemade capacitors (I think that
Saran wrap and aluminum foil will do nicely) and homemade speaker
wire (I think that braiding some Solder Wick with spark plug wire may
do the trick) and sell these items for fantastic amounts of money to
Golden-Eared audio enthusiasts. Easily. It wouldn't be honest, but
sometimes when I read all the ads, it appears that this crowd doesn't
want honesty.

Audio is so darned subjective that no one person can say what's
right. More of my opinion (and that's exactly what it is) should be
showing up in the October 2001 installment of "Q & A"
in "Poptronics". I'll gladly put my 12AX7's on the block. Lessee,
here's the ad copy:

"Specially burned in for smooth audio quality without the sharp edges
one experiences with all new tubes. The lettering on the glass has
been removed to improve the transparency of the sound. Tubes with
specially-rounded exhaust nipples available upon special order."

Dean

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europachris@...
 

Dean, not to get into a big debate here, but there are lots of things going on that test gear cannot measure. I agree with you, as I am an engineer, and I say "speak with data". But, I've listened to solid state amps that measured .001% distortion that drove me from the room and then listened to a single ended tube amp, no feedback, that had 1.5% distortion that had me dancing like a fool.

The ear is a funny thing, and engineering cannot explain it. Measurements of steady state tones tell us one thing, but how an amp reacts in a dynamic time domain is totally different. Amps clip a large percent of the time, and how the amp clips has a lot to do with sound. A graceful clip from a tube amp with no feedback sounds better than the hard clip of a transistor amp with huge amounts of feedback.

This is a debate that has been going on in audio for decades. Let's just say that everyone has an opinion, and whatever makes YOU happy is what counts. I agree that audio is ripe with rip offs, but having spent the last 5 years building my own gear, trying wire, resistors, capacitors, tubes, topologies, and measuring it all, I still don't understand it. I can try 3 different .22uF capacitors in a circuit, and they will ALL sound different. It may be subtle, but with good gear with a lot of resolving power, the differences are there. Each one will measure exactly the same on a scope or distortion meter, but sound entirely different. Each cap has differing inductance, geometry of the wind, dielectric materials, and Equivalent Series Resistance, or ESR. Dielectric effects are particulary audible, causing smearing of the signal due to charge/discharge characteristics. You'll never see this on a scope.

Now, getting on to magic rocks and other stuff. I do agree that this stuff is of dubious value. Many times a person will insist his $2000 cables sound better as he has to convice himself that he didn't just get ripped off.

It's really fun stuff it you look at it at face value. By home brewing and understanding the theory, I can see how much b.s. there is out there. There's also a lot of truth. Tubes DO sound different, as each manufacturer has a slighly different cathode oxide formulation, plate structure, processing procedure, etc. Again, your tube tester may say they are the same, but the signal gets treated slightly different, and it can be heard. For a scope or radio, it probably won't make a diff.

Best,

Chris



TekScopes@yahoogroups.com wrote:

Methinks the tops of my boots are needing a few more inches to clear
the effluent which is building.
<Big snip>
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europachris@...
 

OOOhhhh, this has been the cause of some VERY hot debates on the audio newsgroups.

I certainly won't get into it here. I would LOVE to be the participant of a double blind, being the engineer at heart.

In my experience, the *biggest* impact on sound is the actual design of the circuit. Second on the list is the quality of the transformers (power, choke, and output - tube amps). Frequency response, phase shift, impulse response, core saturation, etc. all are very important in an audio transformer. After that, WAY down on the list are capacitors, then wire, tube sockets, resistors, etc. I've never been able to really tell a big difference between them.

Speaker quality is a huge impact, also. Good speaker drivers have lower distortion in the motor than cheap ones. Most commercial speakers measure really bad w.r.t. distortion.

But again, there is stuff going on that instruments can't measure. I can't explain that while my one cheap Sony CD player sounds pretty awful, but measures just fine, a second unit that has been upgraded with better capacitors in the power supply, better op-amps in the output section, and some other minor mods, sounds completely different. Measures the same, but sounds smoother, better pace and timing, just more toe-tappin' musical.

Has anyone ever wondered why Tek used Telefunken, Amperex, and Mullard tubes in their scopes and not RCA, GE, Westinghouse, or Sylvania, at least in the small signal positions? I would guess that they knew these were higher quality, more reliable, quieter, more linear, and more consistent. Those same parameters make a difference at 10kHz as they do at 5MHz.

Chris
TekScopes@yahoogroups.com wrote:

I am with Dean on this one. �There is a special process called "double-blind
testing" where these sorts of claims can be debunked. �If I understand it
right, double-blind testing amounts to the listener not knowing what
configuration he is listening to and being required to choose between "A" and
"B" a LOT of times, enough to get a pretty good statistical picture of
whether things like tube brands, oxygen free speaker wire, and precision
capacitors REALLY make a difference you can hear. �Most audio nuts that I
know REFUSE to submit to double-blind tests . . . and I think we ALL know why
. . .

Stan
w7ni@easystreet.com
__________________________________________________________________
Get your own FREE, personal Netscape Webmail account today at http://webmail.netscape.com/


James & Kandy Nunn <jnunn@...>
 

"The ear is a funny thing" very true but we do not hear with our ears we hear with our brains and are therefore subject to all the follies of the mind IE we tell ourselves what we want believe and we end up believing it, and I am not talking about Audio.

To me the question has always been that it may sound different but is it necessarily better? Audio is very subjective and having worked in the audio industry in the 60's and 70's (SAE, JBL, Altec) and I can tell you that most of it is hype and the rest is peer pressure. I for one am not a fan of asymmetrical distortion and I find tubes to be "fuzzy" sounding you may call it warm if you wish.

That said and done a couple of years ago I off loaded a Mac 275 for $7500 that I had paid $395 for in 1969. . . anit tubes great!

Jim


Steve B.
 

--- In TekScopes@y..., dhuster@p... wrote:
Ain't no way the human sense of hearing has the bandwidth or the
dynamic range that even modest test equipment has. >
Audio is so darned subjective that no one person can say what's
right. More of my opinion (and that's exactly what it is) should
be
showing up in the October 2001 installment of "Q & A"
in "Poptronics".
I would respectfully suggest we return to our respective fields of
expertise and experience and the central topic of this forum,
Tek 'scopes and related items. Enough misinformation has already
flowed in other technical forums to to run off members over the
whipping of this VERY dead horse therein. I came here to learn what I
don't know, and not to be vicariously ridiculed for what I have
already learned through my own experience elsewhere.

Odd, this is only my second posting and I have yet to get a response
to my first on-topic request for information at mssg #278. This is
the Tek group, right?

Somewhat exasperated; Steve Bringhurst


ilimzn
 

Ah yes, audio mumbo-jumbo. Before everyone jumps on my case, I do a fair amount of audio design and I DO know what i am talking about.

Most people forget there is a way to get very close to 'what it's supposed to sound', even without double-blind tests.
First of all, one can expect that the artist producing the music has given their blessing to the final product, say a CD, and that is a tacit admission that what is on that CD, assuming it was pressed correctly and has no uncorrectable errors, is IT, the reference material.
Next, get a pair of good headphones (it will probably be the last pair you get, anyway) and build a reasonably good amplifier. If you headphones are relatively high impedance dynamic, say 300-600 ohms, you should have no problem getting distortion to extremely low levels, and since it is a well behaved impedance, you will be eliminating 99% of all things that make a particular combo of amplifier and 'speaker' sound different. Then, providing you can separate tonality and spatiality, listen to the material, and you will be pretty darn close to what it's supposed to sound like. Phones have at least an order of magnitude less distortion than any speaker, perhaps excluding directly driven (no transformers!) electrostatics, even at unhealthily high volume.

If a recording is 'bad', then that's exactly how it's supposed to sound from a good system - there should be no 'warmth' where it wasn't in the source, and vice versa. I often find that tube afficionados tend to expect warmth from anything. Such people only declare the liking to a particular sort of distorsion, not to high fidelity. Saying that tubes sound better when clipping than transistors is really the same thing - no clipping is supposed to occur in the first place...

Speakers are the first point of suspicion. And if you go back into the amplifier, having seen many, even so called 'audiophile' ones, a lot needs to be done on education about proper high current wiring, power supply bypassing and filtering, magnetic shielding, and I won't even start on grounding. Some people need to be told the difference between inductors with a core, and ones wound on 'air', as well as between electrolytic caps and all others. Others need more subtle education, such as learning that relay contacts are not linear resistances (and for a VERY good reason) and that they are prone to microphoic effects. Etc, etc.

Saying that cables, tubes, caps, whatever, sound different means nothing without at least theorising why. It was mentioned that the human ear is a curios thing and that it can resolve what measuring equipment cannot. This is nonsense. What measuring equipment? A scope? It operates in the time and amplitude domains and is linear, very different from the ear. There is no ONE parameter that can describe how something will sound, therefore forget about distorsion meters and RLC bridges. There are methods and instruments that can show VERY clearly what the differences between parts are regarding sound, it's just that they are not common, and they are not cheap. A real-time frequency analyzer with spectrogram or waterfall plot capability can tell you a lot of things, but not everyone has one.

Someone mentioned that one listens with the brain. This is very important. I have participated in a study that tested 124 individuals for perception of reverbration. It revealed some interesting facts. One is that although the human ear may have a range which falls off severely over 16kHz, the human brain is capable of operating with phase shifts, that translated into a frequency, extend far above this, perhaps as much as an octave or more. It also suggested that the perception of amplitude is more precise than was originally thought of, and in fact, that it can be trained - a number of people in the test group were 'golden ears', (about 30%) their capability of better percieving minute changes in reverbration time tracked to 94%. Bottom line: things are measurable, what needs to be questioned are traditional methods of measurement.

Z


Phil (VA3UX) <phil@...>
 

At 04:18 AM 6/16/2001 +0000, you wrote:
--

I would respectfully suggest we return to our respective fields of
expertise and experience and the central topic of this forum,
Tek 'scopes and related items. Enough misinformation has already
flowed in other technical forums to to run off members over the
whipping of this VERY dead horse therein. I came here to learn what I
don't know, and not to be vicariously ridiculed for what I have
already learned through my own experience elsewhere.

Odd, this is only my second posting and I have yet to get a response
to my first on-topic request for information at mssg #278. This is
the Tek group, right?
Relax Steve. A bit of humor, venting and off-topic chat is something fairly foreign to a group of mostly serious stodgy engineer/techies (sorry guys) that are interested in oscilloscopes. This sort of thing is a true abberation.

What was your first post about ? Perhaps nobody had an answer and that's why you didn't receive any replies. Run it by us again and we'll get things back on the rails.

Phil


Somewhat exasperated; Steve Bringhurst


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Phil (VA3UX) <phil@...>
 

Well hang on guys. I'm with you to a point. My original response was mainly ridiculing the hype and component pricing that is the consequence of that hype, within the audio community. I am not an audiophile but I am a guitar player (sort of) and I can tell you that despite my technical nature and inherent skeptisicm of statements not accompanied by data, guitar amps sound different with different sets of tubes from different manufacturers. Damned if I know why, but they do. Sometimes radically different. I almost feel that I have a split personality by making that statement, but it's true. It seems that audio/guitar amplifiers are just "tone controls", the tone being the result of the sum of the parts. Whatever the attributes are in high grade 12AX7's that make them sound better than lesser brands in audio applications, they apparently are of no consequence to the operation of the vintage scope circuits we are all interested in and we therefore aren't even aware of them.

Phil

At 04:15 PM 6/15/2001 -0700, you wrote:
I am with Dean on this one. There is a special process called "double-blind
testing" where these sorts of claims can be debunked. If I understand it
right, double-blind testing amounts to the listener not knowing what
configuration he is listening to and being required to choose between "A" and
"B" a LOT of times, enough to get a pretty good statistical picture of
whether things like tube brands, oxygen free speaker wire, and precision
capacitors REALLY make a difference you can hear. Most audio nuts that I
know REFUSE to submit to double-blind tests . . . and I think we ALL know why
. . .

Stan
w7ni@easystreet.com

dhuster@pb.k12.mo.us wrote:

Methinks the tops of my boots are needing a few more inches to clear
the effluent which is building.

Ain't no way the human sense of hearing has the bandwidth or the
dynamic range that even modest test equipment has. There is not a
doubt in my mind that I could write up a page of pure fiction
(including some references to Atlantis and perturbences in the orbit
of Io) and be able to sell my own homemade capacitors (I think that
Saran wrap and aluminum foil will do nicely) and homemade speaker
wire (I think that braiding some Solder Wick with spark plug wire may
do the trick) and sell these items for fantastic amounts of money to
Golden-Eared audio enthusiasts. Easily. It wouldn't be honest, but
sometimes when I read all the ads, it appears that this crowd doesn't
want honesty.

Audio is so darned subjective that no one person can say what's
right. More of my opinion (and that's exactly what it is) should be
showing up in the October 2001 installment of "Q & A"
in "Poptronics". I'll gladly put my 12AX7's on the block. Lessee,
here's the ad copy:

"Specially burned in for smooth audio quality without the sharp edges
one experiences with all new tubes. The lettering on the glass has
been removed to improve the transparency of the sound. Tubes with
specially-rounded exhaust nipples available upon special order."

Dean

To unsubscribe from this group, send an email to:
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Phil (VA3UX) <phil@...>
 

At 10:52 PM 6/15/2001 +0000, you wrote:
Methinks the tops of my boots are needing a few more inches to clear
the effluent which is building.

Ain't no way the human sense of hearing has the bandwidth or the
dynamic range that even modest test equipment has.
It isn't human dynamic range or bandwidth that creates this demand for
certain devices/brands Dean; it's a tone; a certain character of sound
quality. There is no technical definition for this "tone/sound thing" and
I doubt that we can measure it without first knowing what it is.

Phil

There is not a
doubt in my mind that I could write up a page of pure fiction
(including some references to Atlantis and perturbences in the orbit
of Io) and be able to sell my own homemade capacitors (I think that
Saran wrap and aluminum foil will do nicely) and homemade speaker
wire (I think that braiding some Solder Wick with spark plug wire may
do the trick) and sell these items for fantastic amounts of money to
Golden-Eared audio enthusiasts. Easily. It wouldn't be honest, but
sometimes when I read all the ads, it appears that this crowd doesn't
want honesty.

Audio is so darned subjective that no one person can say what's
right. More of my opinion (and that's exactly what it is) should be
showing up in the October 2001 installment of "Q & A"
in "Poptronics". I'll gladly put my 12AX7's on the block. Lessee,
here's the ad copy:

"Specially burned in for smooth audio quality without the sharp edges
one experiences with all new tubes. The lettering on the glass has
been removed to improve the transparency of the sound. Tubes with
specially-rounded exhaust nipples available upon special order."

Dean



To unsubscribe from this group, send an email to:
TekScopes-unsubscribe@egroups.com



Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/


Stan or Patricia Griffiths <w7ni@...>
 

europachris@netscape.net wrote:

Has anyone ever wondered why Tek used Telefunken, Amperex, and Mullard tubes in their scopes and not RCA, GE, Westinghouse, or Sylvania, at least in the small signal positions? I would guess that they knew these were higher quality, more reliable, quieter, more linear, and more consistent. Those same parameters make a difference at 10kHz as they do at 5MHz.

Chris
TekScopes@yahoogroups.com wrote:
I'm not really sure what you mean by "small signal positions" . . . do you mean the first stage of a sensitive amplifier? For letter series tube amplifiers, the first stage was often a cathode follower, probably a 6AK5 (5654), Tung-Sol or RCA, or maybe a stage with gain containing a 6AU6 or 12AU6, Sylvania, RCA, GE, or Westinghouse. In some cases, it was a 7586 nuvistor, RCA or Hitachi. Virtually none of these tubes were Amperex, Telefunken, or Mullard.

After a couple of years working in the test department at Tek in 1960-62, I can say from personal experience that Tek had the very best luck with Amperex 6DJ8's over any other brand used in 530/540 scopes. They tried GE, Sylvania, and some CBS if I remember right. The differences were not subtle. Tek bought untested tubes because they were cheaper and every brand they tried had ten times as many bad new tubes right out of the carton than Amperex. It simply
took too much technician time to weed out the bad tubes that were new right out of the box, so Tek tended to stick with Amperex. I am talking about failures like open filaments, cracked glass, dead shorts between elements, and stuff like that. I don't recall much performance difference between brands of 6DJ8's once you got past the gross infant failures. No new stuff I worked on used many 12AX7's . . . I think there was one in each scope power supply and I
don't recall what brands were used or any significant failure rate of those, any brand. Same for 12AT7's and 12AU7's.

Stan
w7ni@easystreet.com


europachris@...
 

Right on. Same for the Japanese paying mega bucks for the old Western Electric theatre amps. Audio is rife with "the emperor's new clothes" syndrome, and the brain plays a lot of tricks on us.

Chris

TekScopes@yahoogroups.com wrote:

"The ear is a funny thing" very true but we do not hear with our ears we hear with our brains and are therefore subject to all the follies of the mind IE we tell ourselves what we want believe and we end up believing it, and I am not talking about Audio.

To me the question has always been that it may sound different but is it necessarily better? �Audio is very subjective and having worked in the audio industry in the 60's and 70's (SAE, JBL, Altec) and I can tell you that most of it is hype and the rest is peer pressure. I for one am not a fan of asymmetrical distortion and I find tubes to be "fuzzy" sounding you may call it warm if you wish.

That said and done a couple of years ago I off loaded a Mac 275 for $7500 that I had paid $395 for in 1969. . . �anit tubes great! �

Jim




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europachris@...
 

After looking at my 535A this a.m., you are correct. There are tube lineups just as you say in my scope AND CA plugin. However, I don't recall seeing many 6AK5, 6AU6, or 12AU7 tubes from the European manufacturers.

I believe, as you say, that Tek picked the best manufacturer of each particular tube type, covering both performance, longevity, noise, and infant mortality. They did not just blindly sign contracts with one manufacturer like many in the radio business or TV's did (well, like RCA *wouldn't* use RCA tubes in their sets?)

What is truly amazing is the longevity of the scopes, including the tubes within. Tens of thousands of hours and they still work like new.

Chris
TekScopes@yahoogroups.com wrote:

I'm not really sure what you mean by "small signal positions" . . . do you mean the first stage of a sensitive amplifier? �For letter series tube amplifiers, the first stage was often a cathode follower, probably a 6AK5 (5654), Tung-Sol or RCA, or maybe a stage with gain containing a 6AU6 or 12AU6, Sylvania, RCA, GE, or Westinghouse. �In some cases, it was a 7586 nuvistor, RCA or Hitachi. �Virtually none of these tubes were Amperex, Telefunken, or Mullard.

After a couple of years working in the test department at Tek in 1960-62, I can say from personal experience that Tek had the very best luck with Amperex 6DJ8's over any other brand used in 530/540 scopes. �They tried GE, Sylvania, and some CBS if I remember right. �The differences were not subtle. �Tek bought untested tubes because they were cheaper and every brand they tried had ten times as many bad new tubes right out of the carton than Amperex. �It simply
took too much technician time to weed out the bad tubes that were new right out of the box, so Tek tended to stick with Amperex. �I am talking about failures like open filaments, cracked glass, dead shorts between elements, and stuff like that. �I don't recall much performance difference between brands of 6DJ8's once you got past the gross infant failures. �No new stuff I worked on used many 12AX7's . . . I think there was one in each scope power supply and I
don't recall what brands were used or any significant failure rate of those, any brand. �Same for 12AT7's and 12AU7's.

Stan
w7ni@easystreet.com


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James & Kandy Nunn <jnunn@...>
 

"guitar amps sound different with different sets of tubes from different manufacturers. Damned if I know why, but they do. Sometimes radically different. I almost feel that I have a split personality by making that statement, but it's true. It seems that audio/guitar amplifiers are just "tone controls", the tone being the result of the sum of the parts."

As a hobby I have a small (very small) recording studio and I would agree with you even after my earlier post on the hype in Audio. My reason is based on the idea that the guitar/amp constitutes a total instrument and what comes out of the "buzz box" is how the artist wants it to sound. You will note that guitars are always miked rather than patched directly into the mixer you want to capture all that crud the open backed, poorly coupled speaker is producing. Also take a look at the circuits in any guitar amp they tend to be nonlinear, poorly coupled with starved power supplies and I contend that if you used a "audiophile" preamp and amp you would not get the tone you would want, it most likely would sound like a acoustic guitar. basically what we are talking about is the difference between a Strad and a Yamaha violin both sound correct but they sound different and one is not necessarily better than the other just different.

Jim