John Curl's Blowtorch preamplifier part II

[mikelm]

Originally Posted by qusp

what makes you think the terminations on something like a susumu or Vishay SMD is lower quality than caddock?

I do not think that.

I was comparing specified caddocks with cheap industry standard leaded metal film resistors ( not SMD ones ) and I am personally satisfied that they sound ( much ) better.

I don't have much experience with SMD resistors which is why I was asking a question about them - I'm curious to know if cheap industry standard SM resistors tend to sound better that the leaded equivalents due to different industrial processes - from what you say this may be correct.

Massive companies first legal obligation is to provide maximum dividends to their shareholders - I'm not sure this is necessarily compatible with developing resistors for the hi end audio market. This why it's hard these days to buy good quality semiconductors - the mass market, where maximum profits are, is moving in a different direction.

[Esperado]

I would like to add that, with some all digital records, the overall sound is sometime TOO pure, a little empty, or synthetic.
I remember this feeling the first time i listened to the first all digital album "Bop till you drop" from Ry Cooder.
This kind of little 'carbon' distortion, like the one's of the magnetic tapes, helps to bring some life back in a more natural way. It help too to gives an impression of volume or loudness.
I'm not so sure that all distortions are always evil for a home system. We may-be not prefer the same sources if we listen on a Quad or a horn system, too.
I'm not sure, too , that there is not a lot of "cultural" effects in our feelings: i do not feel anything strange any more, years after, with the same Ry Cooder's album. I'm just used to the 'digital sound' ? Or my CD player is better ?

[fas42]

Originally Posted by Esperado

I would like to add that, with some all digital records, the overall sound is sometime TOO pure, a little empty, or synthetic.
I remember this feeling the first time i listened to the first all digital album "Bop till you drop" from Ry Cooder.

We're getting into the subtle areas of what people are listening to, or for now!

Having mentioned Rye Cooder, my benchmark here is the Get Rhythm album. This is from a period when many people complained about the mastering style getting a little too clever, in the sense that everything could be highlighted to the max. And this album can be hard work on an out of balance system ...

So what I listen for in this sort of album is the quality of the voices. If there is a synthetic quality to that, then there is something definitely wrong with the playback, a person's singing voice should always have the quality of "realness" to it; unless the voices have been deliberately manipulated, which then should be an obvious "effect". In other words, natural sounds in the mix should sound exactly so, and artificial, synthesised or manipulated elements will clearly show themselves as such, there will be a nice contrast between the two "qualities".

Frank

[Esperado]

Originally Posted by fas42

If there is a synthetic quality to that, then there is something definitely wrong with the playback, a person's singing voice should always have the quality of "realness" to it;

I remember to have recorded the voices of a well known dancer from "west side story". Somebody had the bad idea to produce him as a singer. This poor guy had a soo poor voice, that we were obliged to add a lot of perifericals to enhance-it and get some presence. Including those stupid 'Aphex". He was singing so much out of tune that we where obliged, believe-me or not, to record *14 tracks* of the same voice, and edit-it word by word !
If you listen to Rihanna in live concert, you will be panic by the way she is so much out of tune: Sometimes, sound engineers are magicians. Don't blame them or your system if, sometimes, there is i little vocoder sound :-)

[gpapag]

Originally Posted by scott wurcer

and I don't particularly like Ouzo or any pastis from any other culture.

This is good for you Scott. Ed’s invitation calls for liver troubles.
But if you have the chance, try smoked (fume) Grappa from Italy.

Originally Posted by fas42

Yes, I know the "dilemma" - every recording has already gone through a series of pots back in the studio; therefore why should one extra on the preamp make such a difference?

Part of the answer is that the pot's in the studio generally have to be reasonably decent, robust units; they wouldn't last long in the industry if they were too obviously flaky; another is that these attenuators are constantly being adjusted during the recording session, the contact points are refreshed frequently during this time

Behind the slider, with older console modules, attenuators were not simple potentiometers.

George

[Esperado]

Originally Posted by gpapag

Behind the slider, with older console modules, attenuators were not simple potentiometers.

They where the worse: you can hear little clics or step changes if you moved the sliders, during mix-down, witch is a requisite.

A lot of more recent analog mixing desks used Penny & Gilles sliders, motorized or not, just to control a DC: the sound level was processed then by awful VCAs, full of distortion.
We regret evil potentiometers, at this time :-)

[jneutron]

Originally Posted by DF96

The crowding depends only on frequency, not magnitude. Skin effect, and hence proximity effect, gives a geometric current pattern governed by frequency alone. Look at the maths in any decent EM textbook. That is why, as jcx(?) said, it can be modelled by adding some inductances to parallel paths.

Looking in the time domain, as you seem to be doing, will create complications when the phenomenon is best considered in the frequency domain. Of course the two must give the same results when done properly, but one will often be easier to deal with.

It is that "easier to deal with" that throws everybody off, the path you are using.

Proximity crowding must be considered in the time domain to determine the 2F distortion I speak of. Approximations as you speak of ignore the actual effect, but is certainly useful for integrated effects such as average power dissipation.

Await actual tests before throwing the baby out with the bath water..

btw, this is a very important issue with ramping superconducting magnetsn and high field quality correction magnets..how else would I already understand it?? Wha, independent thinking? Me??
jn

[DF96]

Take a solution to Maxwell's equations. With exactly the same geometry, double the value of all fields and sources. The result is still a solution. That is all I am claiming, and you are denying.

[john curl]

What we have found from experience with audio, both pro and consumer, is that some pots have MEASURABLE distortion, especially when loaded down at the wiper. Other potentiometers have no easily measured distortion but an identifiable 'signature'. It is VERY difficult to get a 'perfect' pot at any price.
Fixed resistors are easier to find that are pretty good and reasonably low priced, but they also suffer from distortion and 'signature'. It is best to get the 'audiophile and engineer approved' resistors. Audiophile for the sound, engineer for the measured distortion as they cost little more than typical resistors and just will work better, and are safer to use, IF you want the best fidelity possible.

[simon7000]

JN

I have had a chance to think about the last set of measurements and the difficulties I had getting nice clean plots. So here are my ideas of the proper way to do this test.

I have on hand 100 of the Dale CMF55s at 10K and 1000 of the Yaego 10K both rated at 1/4W. I will get out my GR Digibridge and match 4 of each. I will punch an aluminum box to hold plastic shell XLRs at at each end. The diamond of resistors will be held in place at the output end by the connecting leads which will be a twisted pair or 18 gauge or so magnet wire. The input side will be 26 gauge or so magnet wire also twisted. I will do measurements at 100, 316, 1000, 3160, 10,000 Hz. One set will be with the input wires perpendicular to the resistor diamond for minimum coupling. The second set will have the input wires dressed close to the top pair and the third test will be with the wires dressed to diagonal resistors.

Scott,

Don't pull the rope! It is not a snake or a tree or even a wall. Don't pull the rope. As usual I think we both have quite different perspectives on the National IC test results. When I presented what I thought was a simple circuit to write the equation virtually no one could do it. So below is attached the schematic of how I perceive their test setup. You are welcome to try the circuit equations or to model it. I suspect my back of envelope calculations are certainly within an order of magnitude or much closer than the factor of 100 you feel is right. (I can do the equations for a "Noise Amplifier" circuit as shown. The basic issues are not what is the noise gain (I think we agree it is 100) but what is the signal gain and input impedance. I have set the input source to model the AP System 2. I think this will help clear the air about the differences we get, (I think we are starting with different assumptions.)