It was only to show that your numbers are not lunatic, as you see people are now doubting other aspects as these numbers not easily acceptable.
Hayk
Hayk
Yes I understand and thank you for this support.
It is always good to review things and not taking everything for granted.
So for me it was confirmation that the given THD figures were calculated the right way.
Hans
It is always good to review things and not taking everything for granted.
So for me it was confirmation that the given THD figures were calculated the right way.
Hans
Hans, what people are confused, as me, the THD scale on your graphics doesn't have units precised. As you told me you feed Excel with the result file , I thought it is in %. I am sure many others also think so. Edit the first post and in bolt letters precise the THD values are ratios not %.
For the measurements, I don't understand why you need the same shoes to dance and to ski. As you already have two options of .trans you can have one, single cycle 10k samples for FA, and another 100 cycles with1k/cycle samples for FFT. You activate the appropriate one, not only you get precise also faster results.
Hayk
For the measurements, I don't understand why you need the same shoes to dance and to ski. As you already have two options of .trans you can have one, single cycle 10k samples for FA, and another 100 cycles with1k/cycle samples for FFT. You activate the appropriate one, not only you get precise also faster results.
Hayk
Hans,
The big and real question here is:
Why no company in audio industry still using this technical approach right now?
Regards
The big and real question here is:
Why no company in audio industry still using this technical approach right now?
Regards
What gives you the impression they don’t .
And when they do, they are probably not going to tell us.
Companies like Halcro an probably CH Precision to name a few are most likely using these kind of technical approaches.
And somewhat to my surprise, Denon was and may be is still using similar solutions.
Hans
And when they do, they are probably not going to tell us.
Companies like Halcro an probably CH Precision to name a few are most likely using these kind of technical approaches.
And somewhat to my surprise, Denon was and may be is still using similar solutions.
Hans
Sorry,
You are wrong.
Halcro was going out of market.
Denon sell Home Theater products without any related aproach.
Also D Self FAIL in Cambridge and TagMclaren.
What sell today is simple and cheap products. And all companies make the best with low money. It is the real think.
Sorry to desapoint all of you.
You are wrong.
Halcro was going out of market.
Denon sell Home Theater products without any related aproach.
Also D Self FAIL in Cambridge and TagMclaren.
What sell today is simple and cheap products. And all companies make the best with low money. It is the real think.
Sorry to desapoint all of you.
Today the best amp is switched.
Marantz and Jeff Roland uses it and I suppose others are going this way.
I could listen to the magic cube of Jeff Rouland with 805D. Fantastic Amp.
Sorry but it is last century tech.
Marantz and Jeff Roland uses it and I suppose others are going this way.
I could listen to the magic cube of Jeff Rouland with 805D. Fantastic Amp.
Sorry but it is last century tech.
Hans
In fact, you have that right.
I worked with Revox products when I finished Colege. I was also an Philips employee and I know Bruno Putzey's work very well.
Marantz is following that path (Putzey Module). Jeff Rouland has his own way.
These are current techniques - switched amplifiers.
Today's audio lovers often hear noise and distortion and like it. Denon and Halcro are taking this route. It means simple and cheap products for home theater.
Halcro almost left the Hi-End audio market before going bankrupt like TagMaclarem. This kind of products do not pay investment or even pay all company bills.
It is enough to follow what all big companies that work in audio market are doing.
That simple.
Sorry again to dissapoint all of you.
In fact, you have that right.
I worked with Revox products when I finished Colege. I was also an Philips employee and I know Bruno Putzey's work very well.
Marantz is following that path (Putzey Module). Jeff Rouland has his own way.
These are current techniques - switched amplifiers.
Today's audio lovers often hear noise and distortion and like it. Denon and Halcro are taking this route. It means simple and cheap products for home theater.
Halcro almost left the Hi-End audio market before going bankrupt like TagMaclarem. This kind of products do not pay investment or even pay all company bills.
It is enough to follow what all big companies that work in audio market are doing.
That simple.
Sorry again to dissapoint all of you.
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I just had a look in some pictures of 'CH Precision' web site.
I also suppose they are going in switched way too.
I also suppose they are going in switched way too.
We are talking about a buffer here.
A main amp with 25 to 30dB gain will produce much more noise than this buffer, whose input noise is only amplified by 0dB.
Hans
r_merola: There is a note in Douglas Self's amplifier book that for all his work, his crossover displacement concept was one of the few performance improvements that a company actually paid to implement at a cost of 14 components. It seems Jan Didden had some success with a commercial implementation of locally linearized feedback error correcting outputs, and Benchmark is a very successful example in a similar vein, and a whole bunch of composite line drivers and headphone amplifiers have a similar theme. And some, like Cordell’s implementation of error correction are not for consumer applications. And this post is similar, but different in a way that deserves its own analysis and discussion. I feel one of the biggest dangers to the broader electrical engineering community is that many companies can only afford one specialized engineer at most, so there aren't necessarily opportunities to talk and learn from one another. Good thing this is a DIY forum and we are not beholden to commercial inertia, and we get excellent peer review for sharing and there have been great publications from this crowd.
Hans: I reviewed your figure that showed that high frequency distortion was minimized by adding a low feedback buffer around each half of the output. I first started by simulating just the low feedback buffer. I found that the high frequency distortion was much smaller, but then I also found that the standing current was much higher. The local feedback had the effect of changing the relative standing current per bias voltage relationship by making it more sensitive due to the decreased impedance between the two halves. The additional standing current was a large contributor to the high frequency distortion benefits in my simulations, with and without additional loops. It seems this will share some of the strengths and weaknesses of the CFP output stage that the thermal characteristics of the output transistors are partially linearized out, but the standing current now has a greater sensitivity to bias voltage because of the reduced apparent impedance between the halves.
Did you say this has been working for you for five years? It is rare and satisfying to have a project come out well enough that it overcomes my desire to keep tinkering.
Hans: I reviewed your figure that showed that high frequency distortion was minimized by adding a low feedback buffer around each half of the output. I first started by simulating just the low feedback buffer. I found that the high frequency distortion was much smaller, but then I also found that the standing current was much higher. The local feedback had the effect of changing the relative standing current per bias voltage relationship by making it more sensitive due to the decreased impedance between the two halves. The additional standing current was a large contributor to the high frequency distortion benefits in my simulations, with and without additional loops. It seems this will share some of the strengths and weaknesses of the CFP output stage that the thermal characteristics of the output transistors are partially linearized out, but the standing current now has a greater sensitivity to bias voltage because of the reduced apparent impedance between the halves.
Did you say this has been working for you for five years? It is rare and satisfying to have a project come out well enough that it overcomes my desire to keep tinkering.
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@ Mazurek
Thank you for paying detailed attention to the output stages with op-amp.
Forgive when I'm wrong, but my understanding is that you see a problem with the stability of the idle current, possibly leading to a thermal runaway, true ?
Well, too my opinion without any thermal bias voltage compensation, both Version1 and Version3&4 have exactly the same thermal sensitivity.
However, since the op-amps amplify the bias voltage a factor 2, the thermal effects are automatically compensated with a thermally coupled bias circuit, since 0.676Volt has half the thermal sensitivity in mV/degr. as the 1.35Volt on the output transistors, exactly as needed.
Same is true for version 1 where the bias voltage compensates in a 1:1 way.
Hans
Thank you for paying detailed attention to the output stages with op-amp.
Forgive when I'm wrong, but my understanding is that you see a problem with the stability of the idle current, possibly leading to a thermal runaway, true ?
Well, too my opinion without any thermal bias voltage compensation, both Version1 and Version3&4 have exactly the same thermal sensitivity.
However, since the op-amps amplify the bias voltage a factor 2, the thermal effects are automatically compensated with a thermally coupled bias circuit, since 0.676Volt has half the thermal sensitivity in mV/degr. as the 1.35Volt on the output transistors, exactly as needed.
Same is true for version 1 where the bias voltage compensates in a 1:1 way.
Hans
Hans
The Forum purpose is to change ideas and positions.
I give you example of a comercial product apling your idea. It was real world and can care of parts variations and other production issues. More than 30 years old concept.
I also give you ideas of the evolution.
I really hope to help your evolution in your idea or change your mind.
Good Luck
Ronaldo
The Forum purpose is to change ideas and positions.
I give you example of a comercial product apling your idea. It was real world and can care of parts variations and other production issues. More than 30 years old concept.
I also give you ideas of the evolution.
I really hope to help your evolution in your idea or change your mind.
Good Luck
Ronaldo
Thank you for your answer about thermal compensation, it is more subtle than I originally thought. I now see that your overall thermal compensation sensitivity and physics are preserved after adjusting the gain on the VBE multiplier to match the gain of the opamps.
That is a clever point to use a small gain with opamps so it is easy to adjust for their effect on bias. In contrast, the CFP or Renardson output stage use a different gain and can linearize the output transistor about the driver which changes the thermal compensation philosophy.
That is a clever point to use a small gain with opamps so it is easy to adjust for their effect on bias. In contrast, the CFP or Renardson output stage use a different gain and can linearize the output transistor about the driver which changes the thermal compensation philosophy.