John Curl's Blowtorch preamplifier part II

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Nuts, no Status Quo.

Hmmm, I've got some Buddy Rich, he's a drummer.
Do you have any? Buddy, I've got a few let me find
what I have.

My baby girl is really asking for it.
She's lounging on the bed with the
TV controller.

I hope I don't have to take this as a hint,
but she's go the TV tuned to:

Heavenly soft sleepwear and loungewear from notorious lingerie
designer, Carole Hochman, is on QVC.
 
diyAudio Member RIP
Joined 2005
Okay, in the sense that Bart Locanthi "listened" for artifacts, if I put on a Status Quo track, and "Carolyn" is as good as any in this respect, what I'm listening for is the shimmer of the cymbals. These are struck constantly throughout the track, keeping time - you've got a good 3 minutes or so to let the sound register to your hearing ... if you say, what cymbals? then it's an immediate fail!! Seriously, on some system, all one hears is a vague white noise in the background, almost no connection to the real sound of what it actually is.

If you do have a decent cymbal sound then drop the volume right down - does the quality of the strike on the metal improve? If so, then there will be a volume, going up, where the purity of that sound element will deteriorate, the shimmer will start to disappear, go dull - this is power supply problems. Ideally, one can go right to clipping with no loss of quality.

If the system is working well, then the sound image of the drummer working his set will be as clear, and distinct, as on a high quality jazz recording - that's the subjective impression that comes across.

Not to dispute the perceptions---although the notion of a cymbal sound being an issue of the power supply is somewhat far-fetched---but realize the huge effect that level has on timbre, and (probably) perception of attack and decay transients. This occurs of course in live music, but to begin with we have a much greater tolerance of aberrations there than we might do with reproduction.
 
Not to dispute the perceptions---although the notion of a cymbal sound being an issue of the power supply is somewhat far-fetched---but realize the huge effect that level has on timbre, and (probably) perception of attack and decay transients. This occurs of course in live music, but to begin with we have a much greater tolerance of aberrations there than we might do with reproduction.
This is one of first really obvious sound issues I became aware of 30 years ago, which is why I place such emphasis on it. I had a power amp, a Perreaux, which had the defect in the power supply very clearly - I could bring the volume slowly up to a very precise point, every time: clean, clean, clean, then first sign of flatness, which just got worse trying to push past that point. The subjective change of volume during this transition was absolutely minimal, but the change of timbre, in that specific area, was very marked.

As a result of this I started a major process of improving the supplies of that Perreaux, which then allowed me to go well past that earlier point. A Bryston I heard recently was the most competent I have ever heard in this respect, it could go way past any reasonable volume while still maintaining complete control of the treble area.

The simple explanation is that the type of circuit topology used in those amps requires negative feedback to work well for treble clarity, and that feedback starts to struggle when the power supply is modulating badly - stiffen the supply, feedback then works much better, and cleaner treble emerges.
 
Nuts, no Status Quo.

Hmmm, I've got some Buddy Rich, he's a drummer.
Do you have any? Buddy, I've got a few let me find
what I have.
Actually, most R&R is pretty good, provided the drummer uses the cymbals a fair bit. You need something with compressed guitar sound going at a good level, which puts the "load" on the system overall, and then have the cymbals cutting through that sound. When a system gets that right it's remarkable to hear ... and then you realise that's what you hear if you happen to be in a room with a band practising ...

I have an excellent live Jimi Hendrix track, where the drum kit is brilliantly clear, fully resolved - while at the same time Jimi hammers the Marshall.
 
That's a pretty good explanation of the sound.
I'll have to find that Status Quo at the 1/2
price CD store and look for that song on it.

May take me a bit....and worth a listen.

If the drummer has it dialed in and the
production is good it will be worth it,
and now I am aware of your listening
and observations.
 
Wondering what else would work FAS42.

ZZTop - Fool For Your Stockings?

Van Morrison - Moondance?

Chris Rea - Texas?

forgot - Hippies on the Street Corner?

Days of the New - yellow disc? funny a buddy of mine told me
my system sounding like do do and all full of distortion...I tried
to explain to him that is was the "music".
 
whattdayamean?

Maybe....it USED to be Magic,

BUT

You let the SMOKE out!!!!

Now what do we do?

I did notice you had very good left and right balance!
Looks like the two lower and two upper (left and right channel)
resistors fried at the same time.

OR

Was it still running and you wiped them off to get
better measurements from them?

My point was there is two "halls" of engineering around here.

In the blowtorch , they "echo" a lot !
... in other halls ,new things are observed.
Why a MOSFET VAS takes out the drivers on a BJT EF3 ? Same input stage
works on a MOSFET output stage.
Even as it was not my creation , a curious child needs to know.
The last few "blowtorch pages" were triggers to find out some new
material - keep it up (constructive disscussion).

OS
 
AX tech editor
Joined 2002
Paid Member
EXACTLY, John!

If linear parts can accurately model DA, how can there be a non-linear component to DA? Can you tell me how you can model non-linear behavior using only linear parts?

se

I'm with John on this, I hate to admit ;)
You can get no nonlinearity from linear models, but the model is only used to look at linear effects, like charging/discharging.

If you want to know whether DA can lead to non-linearities, you need a model that includes more accurately any nonlinear soakage-release effects - if these are there; I don't know that.

But saying that DA cannot lead to nonlinearities because the model has only linear elements is a prime example of circular reasonoing.

Jan
 
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Wondering what else would work FAS42.

ZZTop - Fool For Your Stockings?
There's plenty out there to use, each can pinpoint a different aberrant behaviour. ZZ Top is good (!), Afterburner is the one for testing driving, heavily processed sound - very dense mix, very studio, excellent for checking how the layers separate, and whether the vocals come through naturally. Also, should have a very high impact, deeeep, bass foundation to the sound. Some may say this is a distorted recording, but it's not! Very full, tight, but smooth sound - can tell one a lot ...
 
RNMarsh said:
The DA comes closest to listener's description of the non-linearities they where compared to no cap (polar electro only)
Sorry, I don't quite get what you are saying here.

Volt Coeff of caps...


VoltageCoefficientofCapacitors-032012-R1.pdf

Well, that rules out Vcoeff for polar and film.
You must have read a different version of the paper. The version I just read says that film caps are stable when compared to high-k ceramics - but surely we all knew that?

jan.didden said:
If you want to know whether DA can lead to non-linearities, you need a model that includes more accurately any nonlinear soakage-release effects - if these are there; I don't know that.

But saying that DA cannot lead to nonlinearities because the model has only linear elements is a prime example of circular reasonoing.
I think you have it back to front. DA is not defined to be linear because it arises from a linear model. DA has been found to be linear and hence can be modelled by linear elements. No circularity involved at all.

I am still puzzled by your attempt to distinguish between "charge/discharge" and audio use of capacitors. I can't think of anything in audio which uses the cap in some other way than charge and discharge. Is there something else you can do with a cap apart from changing the voltage across it by passing a current through it?
 
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