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Old 19th July 2010, 04:05 AM   #4921
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Most people do not realize how linear class A analog circuitry is at perhaps 10-20dB below operating level. Digital just cannot compete.
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Old 19th July 2010, 06:55 AM   #4922
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Quote:
Originally Posted by john curl View Post
Most people do not realize how linear class A analog circuitry is at perhaps 10-20dB below operating level. Digital just cannot compete.
It appears my initial statement has been misunderstood and was not entirely
clear, I am comparing recording formats.

IOW high SR / 24 bit digital versus wide format analog tape ie; 1" or 1/2" 2
track.

T
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Old 19th July 2010, 07:11 AM   #4923
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I do not think that 24 track tape is competitive with anything. My references are 1/2 inch two channel at 30 ips, 1/4 inch two channel at 15 ips in some instances, and 35 mm film, 3 track, at 18 ips.
I agree that Dolbyized 24 track, multitrack recorders full of IC's, etc are not too good.
However, I stand with any class A system at low levels being almost distortionless, by mathematical definition. We might not have thought this very important, even years ago, but it seems to separate digital from analog, in my opinion and experience.
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Old 19th July 2010, 07:53 AM   #4924
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Quote:
Originally Posted by bear View Post
the idea that the digitalized reproduction via a DAC and some sort of filter arrangement is "closer to perfect" may not be quite correct. we've been spending a lot of time discussing exactly how ultra low distortion amps (and preamps, eh?) specifications do not correlate directly with the perceived subjective presentation?

I certainly wish for nearly perfect recording by whatever technological means - but the reality remains that the way that we hear things simply doesn't correlate well to measurement techniques just yet - so if and when it comes, I'll be quite pleased.

I think there is a very simple test that everyone who is motivated can try, any day, any time.

I did this years ago. It is fairly remarkable... take any two mics, string them OUTSIDE and listen inside with your speakers... it works best when the mics can be on opposite or adjacent sides of the building, but outside is the first criterion. Listen for a while...

Try to record it.

Get back to me on it... feel free to send copies of your outside if you wish...

Even using seemingly not-so-great mics and preamps, there is something that appears to me to be NOT captured in the recording process... YMMV, as always...

_-_-bear
Some very interesting posts here.

Thanks for sharing!


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Old 19th July 2010, 03:10 PM   #4925
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Quote:
Originally Posted by bear View Post

Even using seemingly not-so-great mics and preamps, there is something that appears to me to be NOT captured in the recording process... YMMV, as always...

_-_-bear
For one thing two microphones can not capture a full freefield ambient soundscape. Once you decide on stereo the "spaciousness" is mostly faked. The famous Weaver's record is a mix of all mono sources (or so I was told).
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Old 19th July 2010, 03:12 PM   #4926
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I promissed more information about the measurement method at Test Factory.
In the latest Steroplay they tested the new T&A M10 monoblocks that got the reference title. Voltage amplification is done with tubes and current amplification is done with transistors. There is no global feedback. Here is my humble efford of a translation " From the Measurement Lab " :
Resistance desirable !
Ideally an amplifier should act towards the loudspeaker like an ohmic resistor. Only then the backlash of the speaker – caused by the kinetic energy that is contained in accelerated membranes ( back EMF ) or the ineluctable electric charges in the crossovers inductors and capacitors ( that cause phase shift between current and voltage) – will be without any consequences to the amplifier's sound. In order to avoid oscilation, in conventional amplifiers with negative feedback the open loop bandwidth has to be restricted. Unfortunately this is already affecting the quality of sound in the audible range. Not only does the output resistance often raise rapidly beyond 1000 Hertz but also does the distortion raise disproportionately in the high frequency range. The most effective means against that is not to use global feedback – as seen in the T+A M 10. However the effort of supressing distortion will then imensly increase to
hold distortion in check.
They then show the damping factor over frequency from 10Hz to 50kHz, expressed in dbr A ( whatever that is ) that is in the case of the M10 a nearly straight line at -42.5 dbr and they show distortion spectra over a bandwidth of 20Hz to 20kHz that look very similiar when frequency goes up. They also show harmonic distortion over power where second harmonic is dominating until 8W and the rise in distortion is smooth.
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Old 19th July 2010, 03:23 PM   #4927
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Quote:
Originally Posted by Joachim Gerhard View Post
I promissed more information about the measurement method at Test Factory.
In the latest Steroplay they tested the new T&A M10 monoblocks that got the reference title. Voltage amplification is done with tubes and current amplification is done with transistors. There is no global feedback. Here is my humble efford of a translation " From the Measurement Lab " :
Resistance desirable !
Ideally an amplifier should act towards the loudspeaker like an ohmic resistor. Only then the backlash of the speaker – caused by the kinetic energy that is contained in accelerated membranes ( back EMF ) or the ineluctable electric charges in the crossovers inductors and capacitors ( that cause phase shift between current and voltage) – will be without any consequences to the amplifier's sound. In order to avoid oscilation, in conventional amplifiers with negative feedback the open loop bandwidth has to be restricted. Unfortunately this is already affecting the quality of sound in the audible range. Not only does the output resistance often raise rapidly beyond 1000 Hertz but also does the distortion raise disproportionately in the high frequency range. The most effective means against that is not to use global feedback – as seen in the T+A M 10. However the effort of supressing distortion will then imensly increase to
hold distortion in check.
They then show the damping factor over frequency from 10Hz to 50kHz, expressed in dbr A ( whatever that is ) that is in the case of the M10 a nearly straight line at -42.5 dbr and they show distortion spectra over a bandwidth of 20Hz to 20kHz that look very similiar when frequency goes up. They also show harmonic distortion over power where second harmonic is dominating until 8W and the rise in distortion is smooth.
I think a lot of people here wouldn't agree with this whole seemingly cause-and-effect anectote. Why must Zout be resistive for best sound?
Even if restricting the OL BW raises distortion with freq, and negatively effects sound Q, the distortion of the T+A is most probably (much) higher in the "crtitical midband"; does that NOT negatively effect the sound Q?
Why is -42.5dBr over the band better than, say, my amp that starts at -70dBr at 100Hz and then rises to -42.5dBr at 18kHz? Yes it rises with freq but is still lower than the T+A....

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Last edited by jan.didden; 19th July 2010 at 03:30 PM.
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Old 19th July 2010, 03:50 PM   #4928
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Originally Posted by janneman View Post
...the distortion of the T+A is most probably (much) higher in the "crtitical midband"; does that NOT negatively effect the sound Q?
Almoat certainly not. I've never heard one, but I would say the distortion would be completely inaudible, and vastly outweighed by the increased "life" from the lack of NFB.

Ask Joachum about my big zero NFB dpa150 poweramps, and how they sound. The distortion is horrifying but it sounds magnificant!

Measured distortion means absolutely ZERO in my experience from the sound quality point of view.

You really have to try a zero NFB poweramp to understand what I'm talking aboiut.

Regards, Allen
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Old 19th July 2010, 04:40 PM   #4929
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Originally Posted by scott wurcer View Post
For one thing two microphones can not capture a full freefield ambient soundscape. Once you decide on stereo the "spaciousness" is mostly faked. The famous Weaver's record is a mix of all mono sources (or so I was told).
Scott - of course two mics can not capture anything more than two mics can capture - tautology?

My point is not that... and imo "spaciouness" is not faked in a true "stereo" recording - for example M/S or Blumlein, etc... etc... it is imperfect of course, but so is everything else in audio.

Try it before you criticize it?

My point is/was that there is something present in the direct "feed" that is lost in the recording and very much so in the chain of transfers that we are usually on the tail end of...

_-_-bear
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Old 19th July 2010, 04:46 PM   #4930
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Quote:
Originally Posted by Joachim Gerhard View Post
T&A M10 monoblocks
Rather pretty looking, though a bit Burmester.

http://www.taelektroakustik.de/uploa...LOG_M10_DE.pdf
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