john curl said:Hi folks, this is your old geezer talking!Yes, back when I was thirty, I was dating both a 20 year old San Francisco stripper, who lived in North Beach, and a 20 year old Las Vegas showgirl, down on her luck at the moment.
How is it going for you?
Let's just make sure they know that we may be old dogs, but we can always learn new tricks 🙂.
Bob
john curl said:
Yes, we think a like in many ways. I was intending to take a look at the measurements on the Halcro, Boulder and Ayre amps to see if there is something fishy in common.
Bob
john curl said:
Thanks, John. We really appreciate your presence here, even if we don't always agree. You stir the pot and make us THINK. You have successfully managed to put the coil thing really under the microscope here, and everybody wins as a result of that. I personally have learned from you by being challenged by you.
Best,
Bob
john curl said:
John, I think the jury is still out on whether I am "wrong" or not about what I have said about the Stereophile measurements on the JC-1. Keep in mind that I have just reported on what those measurements appear to suggest. I have not stated that your JC-1 has 2 uH of effective output inductance. In my last post on that I plainly pointed out that there remains a mystery in the measurements.
Let us know the results of your spectrum analyzer-based impedance measurement of the JC-1 that I suggested.
Bob
After rebuilding one channel, I just drove a signal into my amps output through a 1.47K resistor. Ten volts pp from the gen, and four millivolts pp at the amp output, at 20kHz, while loaded with 8 ohms. Sweeping the frequency, the amplitude decreases linearly down into the noise floor. That would seem to be an output impedance of about half an ohm, with the 3uH/10ohm output network contributing less than half. Did I do that right and does it seem reasonable? (I should have measured on the inside of the output network as well, but I didn't yet)
Oops, didn't include the 8 ohms to ground in parallel with the amp in the calculation. That would make things a bit worse, but not a huge amount. What would normal numbers be for this test?
Hi Bob, Has your son married yet? Are you also a grandfather? I have 3 grandchildren, and my son is almost 37. I made him while married to my first wife (now called grandma) back before I was 30.
The same accounts for me as well. I do usually not regard people being stupid or unfriendly or both, who disagree with me. Discussing and disagreeing with intelligent people is much more interesting than doing the same with stupid ones. This kind of discussions are always a source of creativity if the tone isn't getting hostile.
Regards
Charles
While we are on the subject of the Halcro design, I seem to recall that they do not "recommend" the amp for use with loads under 4 ohms!? Which makes me scratch my head. 
What does this say about the design of the ootpoot stage/topology?
Speaking of which... a mildly interesting side story... a short time after the Halcro first emerged - somewhat before Stereophile discovered it, I had a phone convo with a friend of mine from Iowa about something that happened long before Halcro existed. Years before, at the time he was a recently graduated EE, he came here for a visit (i'm in upstate NY) towing a "200watt" or maybe it was a 100watt amplifier. At the time I was just getting started with my line of Symphony No.1 amplfiers (they do use an output inductor). And we compared them listening on my Acoustat IV Esl speakers.
My impression was that it was quite good, nothing bad, but a bit "too clean" sounding perhaps... he was suitably vague about the inner workings when I questioned him about it. I thought nothing more of it actually. Oh, it was Mosfet, IRFs iirc...
To continue on, so I was on the phone talking to him about the Halcro patent, having just found it and read it through... he says something like this - "oh that...? yeah, well my amp, the one I brought out to you? It basically did all that (the low distortion, feedforward, multiple loops, bootstrapping, etc...)." He's a real low key guy. So, I said, hey why didn't you say anything to me, market it, patent it, or anything? His response, true to form, was something like "I didn't think it was anything very special... it was just a school project..."
_-_-bear
What does this say about the design of the ootpoot stage/topology?Speaking of which... a mildly interesting side story... a short time after the Halcro first emerged - somewhat before Stereophile discovered it, I had a phone convo with a friend of mine from Iowa about something that happened long before Halcro existed. Years before, at the time he was a recently graduated EE, he came here for a visit (i'm in upstate NY) towing a "200watt" or maybe it was a 100watt amplifier. At the time I was just getting started with my line of Symphony No.1 amplfiers (they do use an output inductor). And we compared them listening on my Acoustat IV Esl speakers.
My impression was that it was quite good, nothing bad, but a bit "too clean" sounding perhaps... he was suitably vague about the inner workings when I questioned him about it. I thought nothing more of it actually. Oh, it was Mosfet, IRFs iirc...
To continue on, so I was on the phone talking to him about the Halcro patent, having just found it and read it through... he says something like this - "oh that...? yeah, well my amp, the one I brought out to you? It basically did all that (the low distortion, feedforward, multiple loops, bootstrapping, etc...)." He's a real low key guy. So, I said, hey why didn't you say anything to me, market it, patent it, or anything? His response, true to form, was something like "I didn't think it was anything very special... it was just a school project..."
_-_-bear
Some people say they cannot hear o/p coils, others say that can.
Assuming for now there is a difference to be heard and some people apparently cannot hear this, my question is:
Is it down to hearing or is it down to audio systems ?
Could be either or bit of both, but for some reason I tend to give people's ears the benefit of the doubt.
I have found over the years ( no children or grandchildren but just about old enough for both ) that there are many little electronic circuit elements within an audio system that, if not designed with understanding and care, can give rise to non signal related noise.
By this I mean, even though sometimes it is the combination of circuit design & signal that gives rise to this noise, the noise itself has no harmonic relationship to the music.
Even really clean mains in combination with common power supply designs will generate heaps of this stuff and of course normally mains electricity is very noisy in it's own right.
Other culprits include speakers combined with low o/p impedance amps and small bypass caps across large electrolytics. I'm sure there are many others I did not mention.
For me it is the combination of all these noise sources that mess up the sound of a system. It does not matter if this noise is in audio band, ultra sonic or RF it still seems to find a way of messing things up and making the music sound awful.
Perhaps in a system where all or nearly all of these problems have been attended to the signature "sound" of an output coil will be perceptible and stand out as being unnatural, whereas in a system with other noise sources it may be masked.
I also notice that different kinds of music highlight these issues to a greater or lesser extent - for me classical full orchestra is by far and away the biggest challenge.
Most of us have not heard each other systems therefore we have no idea how they compare regarding absolute sound quality. I think this substantially hinders coherent debate and although we have no way of getting around this I guess we have to bear it in mind as an unknown variable.
n.b. As I did not try this listening test yet I do not know where I stand in this matter
cheers
mike
Assuming for now there is a difference to be heard and some people apparently cannot hear this, my question is:
Is it down to hearing or is it down to audio systems ?
Could be either or bit of both, but for some reason I tend to give people's ears the benefit of the doubt.
I have found over the years ( no children or grandchildren but just about old enough for both ) that there are many little electronic circuit elements within an audio system that, if not designed with understanding and care, can give rise to non signal related noise.
By this I mean, even though sometimes it is the combination of circuit design & signal that gives rise to this noise, the noise itself has no harmonic relationship to the music.
Even really clean mains in combination with common power supply designs will generate heaps of this stuff and of course normally mains electricity is very noisy in it's own right.
Other culprits include speakers combined with low o/p impedance amps and small bypass caps across large electrolytics. I'm sure there are many others I did not mention.
For me it is the combination of all these noise sources that mess up the sound of a system. It does not matter if this noise is in audio band, ultra sonic or RF it still seems to find a way of messing things up and making the music sound awful.
Perhaps in a system where all or nearly all of these problems have been attended to the signature "sound" of an output coil will be perceptible and stand out as being unnatural, whereas in a system with other noise sources it may be masked.
I also notice that different kinds of music highlight these issues to a greater or lesser extent - for me classical full orchestra is by far and away the biggest challenge.
Most of us have not heard each other systems therefore we have no idea how they compare regarding absolute sound quality. I think this substantially hinders coherent debate and although we have no way of getting around this I guess we have to bear it in mind as an unknown variable.
n.b. As I did not try this listening test yet I do not know where I stand in this matter
cheers
mike
john curl said:
Hi John,
Are you saying that if I add a 2 uH/2-ohm inductance-resistance network, made in a virtually perfect way (no nonlinearity, etc) outside of, say your JC-1, that I will hear an audible degradation?
This is a key question, because it helps separate the linear issues from the nonlinear issues.
Although I must admit to having some difficulty tracking what Graham has been saying, I think he is largely alluding to such linear effects, and that he would answer yes to this question.
Thanks,
Bob
john curl said:
Hi John,
No. Have you seen the movie "Failure to Launch?".
I am a step-grandfather via my second wife.
By today's standards, we are not old, we are just entering our prime.
Bob
bear said:While we are on the subject of the Halcro design, I seem to recall that they do not "recommend" the amp for use with loads under 4 ohms!? Which makes me scratch my head.
Speaking of which... a mildly interesting side story... a short time after the Halcro first emerged - somewhat before Stereophile discovered it, I had a phone convo with a friend of mine from Iowa about something that happened long before Halcro existed. Years before, at the time he was a recently graduated EE, he came here for a visit (i'm in upstate NY) towing a "200watt" or maybe it was a 100watt amplifier. At the time I was just getting started with my line of Symphony No.1 amplfiers (they do use an output inductor). And we compared them listening on my Acoustat IV Esl speakers.
My impression was that it was quite good, nothing bad, but a bit "too clean" sounding perhaps... he was suitably vague about the inner workings when I questioned him about it. I thought nothing more of it actually. Oh, it was Mosfet, IRFs iirc...
To continue on, so I was on the phone talking to him about the Halcro patent, having just found it and read it through... he says something like this - "oh that...? yeah, well my amp, the one I brought out to you? It basically did all that (the low distortion, feedforward, multiple loops, bootstrapping, etc...)." He's a real low key guy. So, I said, hey why didn't you say anything to me, market it, patent it, or anything? His response, true to form, was something like "I didn't think it was anything very special... it was just a school project..."
_-_-bear
I believe that the Halcro patent would never stand up in court. For one thing, it totally fails to disclose applicable prior art. Secondly, Candy's addition to the prior art, bootstrapping based on the output, is of dubious value and novelty.
I also scratch my head on Halcro's inability to perform well into a 2-ohm load.
Bob
Maybe we should ask our sons if they can hear a coil.
They do have better ears than we old dogs have. 🙂
Cheers,
They do have better ears than we old dogs have. 🙂
Cheers,
Bob Cordell said:
Bob Cordell said:
Hi Bob,
I have also bootstrapped my I/P stage based on the output signal, which (the latter) is flat to about 250kHz. It out performs a cascode topology. So, under which conditions it is of dubious value?
Cheers, Edmond.
PS: In case you need more info to answer my question, I'll send you the schematic of the I/P stage.
Hi Hartono,
there is just a small problem. My recent amps
http://www.diyaudio.com/forums/showthread.php?postid=1215298#post1215298
I am listening to have neither Zobel, nor output coil. So it is very very difficult to disconnect them 😀
there is just a small problem. My recent amps
http://www.diyaudio.com/forums/showthread.php?postid=1215298#post1215298
I am listening to have neither Zobel, nor output coil. So it is very very difficult to disconnect them 😀
Hi PMA,
hehehhee you're funny
so just tap on the speaker (no crossover) what did you see on the scope ?
hehehhee you're funny
so just tap on the speaker (no crossover) what did you see on the scope ?
Yes, I am very funny. I have no crossover, as my speakers are active. My filters are on line-side. And I am taking a scope at speaker terminals anytime I develop a new amp. Not only the scope, but FFT as well. And I can load the amps with 3uF without going into stability problems. Yes, I am very funny.
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