John Curl's Blowtorch preamplifier part II

[Max Headroom]

Originally Posted by SY

Depends on what you're doing to screw up their operation.

Normal typical, for example Yamaha or Pioneer or Denon etc etc cdp, amplifier, speaker setup.
No swps items operating in the house.

So where's the screw up ?.

Dan.

[john curl]

Once again, I have to search for a document to explain myself. I have an AES preprint around here somewhere. Still looking, but the jest of it is: Asymmetrical waveforms appear both in nature and in the electronics often due to certain human voices, etc. Of course, it is NOT steady DC offset, but it has to accounted for and corrected in FM transmission, for example. This is also the cause for the main contribution to dielectric absorption from many capacitors.
Where is the conspiracy? Why didn't they tell me about it?

[Max Headroom]

Hi John, by definition recorded music is AC coupled, so provided the playback system is DC coupled or has low enough low frequency response, how is waveform asymmetry a problem in playback systems ?.
In broadcast, announcer voice waveform asymmetry is a problem, more particularly with AM transmission, and several signal polarity processor types have been devised over time to ensure maximum average modulation without allowing AM transmitter 'cut-off'.

Eric.

[PMA]

This "quasi DC" appears or not depending on integration averaging time. Effect depends on low-frequency response of the system.

[marce]

Again, having asked numerous times and been ignored (possibly because there is no answer that suits the believers),
John Max etc, WHY is this wonderful device only available to Audio tweekers and in esoteric audio shops, why? Why is it not available to otheres in the electronics industry?
And finaly why do people like Henry Ott not bow at the door of Mr Baybee for creating a component (resistor wrapped in stillpoint ERS, with a bit of shrink wrap) that would be one of the biggest advances in noise reduction?
One final thought, everyone seems to agree on the over the top pseudo science used to describe the BQP, yet it never changes, is this because it sounds so good to the punters who are likely to buy such a thing!
Of course some people can hear the low level distortion added to digital files when they are mover around servers and systems, even thought the file content is exactly the same.
And how aqccurate does the clock have to be! more well we could measure somthing if we had the kit, jeeze, Audio repreduction is engineering, I know some like to think it isn't but sorry it is, the art is creating the music, playbakc is just engineering...

[Lukas87]

It's real breakthrough for high-order QAM and space probe communication. Why it's not used there?

[PMA]

Probably Mr. Bybee does not intend to sell it at 1 buck (per pair).

[kgrlee]

Originally Posted by john curl

Latest TAS, Mar 2012 Editors Choice:

Err.rrh! JC, could you please explain the relevance of TAS's fine pontificating on the subjects under discussion.
___________________

Real music has a dynamic DC component just like Richard says. It has been measured, and written about. It is the FUNDAMENTAL factor in detecting dielectric absorption in Walt's, Scott's and my testing of caps, back in the middle '80's.

As I'm really a speaker & mike man, I've a pretty good idea of which mikes have response to DC.

I'm not sure what is 'dynamic DC' but I'll pretend to accept this FUNDAMENTAL factor

Could you tell us which recordings of 'real music' have this FUNDAMENTAL factor and were used in Messr's Walt, Scott & your testing in the 80's?

Were these vinyl, mastertapes from your supa dupa Ampex machines, mastertapes originally made with FM machines with response to DC (albeit dynamic DC)?

Gasp! You mean they were evil Digital recordings?

I can probably find out what mikes were used ...

[Max Headroom]

Originally Posted by marce

Again, having asked numerous times and been ignored (possibly because there is no answer that suits the believers),
John Max etc, WHY is this wonderful device only available to Audio tweakers and in esoteric audio shops, why? Why is it not available to others in the electronics industry?

I believe that these devices are available to all.

And finally why do people like Henry Ott not bow at the door of Mr Bybee for creating a component (resistor wrapped in stillpoint ERS, with a bit of shrink wrap) that would be one of the biggest advances in noise reduction?

I have been told in the past that "the degree of NR is only a dB or so.....still that can be the difference when you are passively listening for an enemy submarine"
Personally I think there is more to it than that.....increase in intelligibility of sounds would be what the submariners are seeking.
As I understand it, the submarine guys listening in on headphones are usually musos with well trained hearing, and their job is to pick out enemy submarine sounds in amongst the clutter of ocean sounds, not an easy job apparently.
Any improvement of SN, distortion or clarity of sounds emerging from their headphone/amplifier/hydrophone systems would be most advantageous.

One final thought, everyone seems to agree on the over the top pseudo science used to describe the BQP, yet it never changes, is this because it sounds so good to the punters who are likely to buy such a thing!

The audio world (ditto automotive, cooking, whatever worlds etc) are full of BS statements that don't actually claim anything.
I have a pair of Dr Dre headphones on loan....they sound ok but not wonderful or particularly accurate....certainly not mixdown monitor headphones.
I have not A/B'd them yet to my Stax electrostatics...I expect them to compare miserably.
So these Dr Dre headphones sell something like 20 million pairs per year and the entry price is $299.00, then $399.00, then $499.00.
In the user manual there are absolutely no specs given....the only semi-technical text is warnings about high SPL damaging hearing.
So it all comes down to, if Dr Dre says they are good, then they must be good....IOW in this case it is all about marketing and fashion.

And how accurate does the clock have to be! more well we could measure something if we had the kit, jeeze, Audio reproduction is engineering, I know some like to think it isn't but sorry it is, the art is creating the music, playback is just engineering...

In the case that I cited, stable and master clocked system is required to obtain recordings that are as near as dammit as identical, except for any circuit changes made.

Dan.

[kgrlee]

Originally Posted by JC

The Bybee devices appear to reduce a certain kind of 1/f related modulation noise. This means that you have to have signal, to measure the noise, .... Only with a signal, that then, has to be removed almost completely, does the noise difference show up on test instruments.

BTW, the test JC describes and you quote is called THD testing.

Originally Posted by Max Headroom

I well know what THD testing is and how it works, thank you.
IME Sinewave THD testing does not show any reliable quantifiable result when measuring system effects due to ferrite filters at audio frequencies, however real world loopback music testing does reveal effects.

JC's description sounds suspiciously like the Classic description of THD measurement which includes noise. Classic THD measurement is very well suited to measure modulation noise.

But I do agree with you that "real world loopback music testing" may be more appropriate though IME, none of these really tell you more than simple Classic THD and frequency response.

Of these "real world" tests, there is the Baxandall/Walker original used by QUAD which compensates for the 'linear' distortions (eg frequency response) leaving the non-linear distortions to be listened to. There's Hafler's version which doesn't bother so will reveal 'linear' distortions too.

In this evil digital millenium, AudioDiffmaker is of the Hafler type.