As per what I said on the Snake Oil thread, nah, no time lately but I do now have the ingredients I want for the experiment.
When it is time I will let it be known.
Dan.
Bill, there are reasons and there are excuses.
Mine are reasons, what are your excuses for your characteristic negative and whinging pom behaviors as evidenced in your posts.
Bill, I am experimenting with effects of some deep aspects of physics as pertaining to audio and and further pertaining to other fields.
As current status stands I am able to walk up to any audio system and advantageously alter the system behaviour and consequent acoustic output be the system analog or digital, same with video systems and lighting systems.
Permanent magnet loudspeaker drivers, permanent magnet headphone drivers, permanent magnet microphones and electrostatic headphone driver behaviors are also easily directly alterable.
Multiple audio professionals verify system acoustic changes and indicate preference, multiple non professional listeners verify acoustic changes and indicate preference, one professional wine judge wrote a report describing changes to red wine.
The kinds of changes/control I am exploring are to my mind significant and the implications are deep and far reaching.
So Bill, what is it that you do in your day job and what significant research are you undertaking ?.
What is your interest, what is your passion, what drives you, who are you really ?.
Dan.
Now back to what it takes to make a successful audio amplifier design.
While Mark Johnson gave a number of factors, what I am most concerned with here is some almost ignored factors included in the Otala, Lohstroh AES paper 1973 that made one of the first successful sounding power amps in audio history. This included high open loop bandwidth, as well as slew-rate, open loop linearity, and very high effective bandwidth (for the time). If Jan Lohstroh alone would have made it, without the changes suggested by Matti Otala, it would have been just another good design, ignored by serious audio listeners. Why this is so, still confounds the critics, but it still appears to be more important than just a 'better' thd measurement, etc. and this has been proven out by a number of successful designs that have that extra 'quality' not shared by the bulk of audio products.
While Mark Johnson gave a number of factors, what I am most concerned with here is some almost ignored factors included in the Otala, Lohstroh AES paper 1973 that made one of the first successful sounding power amps in audio history. This included high open loop bandwidth, as well as slew-rate, open loop linearity, and very high effective bandwidth (for the time). If Jan Lohstroh alone would have made it, without the changes suggested by Matti Otala, it would have been just another good design, ignored by serious audio listeners. Why this is so, still confounds the critics, but it still appears to be more important than just a 'better' thd measurement, etc. and this has been proven out by a number of successful designs that have that extra 'quality' not shared by the bulk of audio products.
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Hi Richard,
Gee, now there is something I'd like to use. I didn't know about the Tek P6042. That looks like exactly what would be useful.
Question, can you separate the DC and AC response, or do you get the complete current waveform all the time? I guess it doesn't matter since you're using the 'scope as a display instead of a meter.
Thanks for bringing that model up. Most of the time I only need a DC reading, but then I avoid AC current measurements since I don't have any assets that will make those measurements.
Best, Chris
Gee, now there is something I'd like to use. I didn't know about the Tek P6042. That looks like exactly what would be useful.
Question, can you separate the DC and AC response, or do you get the complete current waveform all the time? I guess it doesn't matter since you're using the 'scope as a display instead of a meter.
Thanks for bringing that model up. Most of the time I only need a DC reading, but then I avoid AC current measurements since I don't have any assets that will make those measurements.
Best, Chris
Hi John,
I'm going to stick to my own belief that good amplifier design comes about from careful measurements and careful listening together. Any design that ignores either tool will not be as good as it can be.
Right now I'm listening to a Nakamichi TA-2 receiver that sounds pretty good compared to a stock unit. The distortion performance isn't as good as it could be because the output stage is not encompassed by the feedback loop. If the output stage were improved, it would certainly measure better - and sound better. This I know from listening (and measuring) to the larger Stasis amplifiers.
-Chris
I'm going to stick to my own belief that good amplifier design comes about from careful measurements and careful listening together. Any design that ignores either tool will not be as good as it can be.
Right now I'm listening to a Nakamichi TA-2 receiver that sounds pretty good compared to a stock unit. The distortion performance isn't as good as it could be because the output stage is not encompassed by the feedback loop. If the output stage were improved, it would certainly measure better - and sound better. This I know from listening (and measuring) to the larger Stasis amplifiers.
-Chris
You mean reducing the distortions in some way?
I see we have circled the wagons again around the same campfire telling the same old stories. Reminds me of Blazing Saddles.
Determine Cout
Can I come back to how to measure output capacitance of the HV amplifier. Not trusting the cheap cap meter I have I tried an indirect way.
In the attached, the smallest BW graph is with an external 56pF cap attached to the output.
Since neither curve goes to -3dB in a smooth way I compared roll-off frequencies at -1dB and got about 80kHz and 135kHz. Can I infer the intrinsic output cap of the stage from this?
Rout is around 2.5kohm.
Edit: accounting for the used test adapters and receiver attenuators, actual mid-freq circuit gain is about 54dB
Jan
Can I come back to how to measure output capacitance of the HV amplifier. Not trusting the cheap cap meter I have I tried an indirect way.
In the attached, the smallest BW graph is with an external 56pF cap attached to the output.
Since neither curve goes to -3dB in a smooth way I compared roll-off frequencies at -1dB and got about 80kHz and 135kHz. Can I infer the intrinsic output cap of the stage from this?
Rout is around 2.5kohm.
Edit: accounting for the used test adapters and receiver attenuators, actual mid-freq circuit gain is about 54dB
Jan
Attachments
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My 12 cents regarding power amplifiers, based on experience:
- stability even with very difficult complex loads, no problems if the load is suddenly disconnected
- high output current capability
- excellent immunity to both air-coupled EMI interferences and supply line interferences
- sophisticated wiring topology immune to grounding scheme of remaining audio chain components
- frequency compensation network that assures high loopgain (feedback factor) even at the upper end of audio band
- very low and as linear as possible output impedance
Reasonably high slew rate and full power bandwidth at least 100kHz as a rule of thumb, no need to emphasize.
Thanks John, there ain't nuthin gonna stop me on this.
I'm off soon to work a Staff Christmas show with a curtain hidden second stage super secret surprise performance by one of Aus's top/most famous/enduring performers.
The venue is an exclusive restaurant huge room overlooking Perth City and waterways from high above......quite a Christmas party !.
I will see how 'The Voice'* will improve with a bit of system tweaking, lol.
Anyway, my observations are unequivocal, and if there are texts that describe the mechanism I haven't found them.
My mention 'the implications are deep and far reaching' goes deeper, much deeper than I am willing to let on about here on this forum, and the reason is not fear of ridicule.
The most of us are prone to a host of environmental influences good and bad.
Most of these influences are obvious and some are not, and some of the bad influences have been 'hidden' from our view by means of censorship and miseducation.
Some of these bad influences can be ameliorated and turned to neutral or beneficial.
Audio is a subfamily, the applications of what I am exploring is essentially universal and for the benefit of all, this is my driver.
In the meantime I get more enjoyable audio, wines and car and that's just for starters.
Dan.
* - Aussies will work out who it is.
Botanic Gardens and Parks Authority - Kings Park
https://www.google.com.au/search
http://www.frasersrestaurant.com.au/wp-content/gallery/frasers-kings-park/fr_050.jpg
http://www.frasersrestaurant.com.au/wp-content/gallery/frasers-kings-park/fr-cityscape.jpg
Plenty cold here, do you let the humidity drop? Did you see Microsoft's anechoic chamber, they really moved the goal post on that one?
Yes. And it is enough to hit a finger on the membrane of a bass speaker with its connectors open VS shorted to understand what Back EMF is about.
I wonder why nobody here had reacted to the words:
"Back EMF does not occur in a properly designed and aligned speaker system. "
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Because for 6 months now you have stated that you have two bit identical files that 'clearly' sound different. But when asked to provide them for others to listen to you suddenly need to make more. Sounds like an excuse.
Except you are not. You are mixing gloop.
What drives me is providing for my loving wife and 6 kids. What I do has no bearing on the fact that you are either about to win a nobel prize or completely deluded.
You really do not understand 'research'. But you have been told that many times.
Ed: All chill here. Making fruit cake with a two year old is a wonderfully cathartic experience.
Hi Tryphon,
Because it is so basically wrong that it doesn't dignify a response. Everyone here is probably aware of the truth.
Hi Scott,
-Chris
Because it is so basically wrong that it doesn't dignify a response. Everyone here is probably aware of the truth.
Hi Scott,
Generally, yes. Pick your most problimatic ones and try to solve them working your way down the list. That includes the basic concept.
Well, exactly. The same old question was posed by the same old person. The only response will be the well-worn one that does not split the audience.
-Chris
In some circles back EMF has negative connotations, why I don't know, it is inherent in the physics of the speaker and not something that can be eliminated. In the case of current drive I guess it is no longer a force.
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