"<-118 dB relative to full output at any output level below clip, stereo, 1 kHz"
"relative" so does it really mean anything? What is full output? How far into clipping are they driving?
"relative" so does it really mean anything? What is full output? How far into clipping are they driving?
It means relative to the fundamental. THD is measured in percent and that is relative in the same way.
Clipping rediscovered -
besides the THd number --- BenchMark... if you have followed their digital designs (ADC/DAC).... I have both DAC -- first gen and newest gen.... they have also focused on clipping in their digital designs.... the second generation DAC has more headroom to prevent clipping. Power amp has clipping indicators and gain adjust... again they see a clipping issue. Also offer more power to help avoid clipping (assuming high enough Z min). A lot of fuss about clipping - they must be seeing it often and have reintroduced the clipping indicator lights as part of their marketing story. A 21 century (re) discovery.
Just an observation.
[I have a couple more weeks to get ready until I leave the country; but thought it was interesting because I brought up clipping also recently]
What can you do along those patent lines with OPS .... SIM first?
THx-RNMarsh
besides the THd number --- BenchMark... if you have followed their digital designs (ADC/DAC).... I have both DAC -- first gen and newest gen.... they have also focused on clipping in their digital designs.... the second generation DAC has more headroom to prevent clipping. Power amp has clipping indicators and gain adjust... again they see a clipping issue. Also offer more power to help avoid clipping (assuming high enough Z min). A lot of fuss about clipping - they must be seeing it often and have reintroduced the clipping indicator lights as part of their marketing story. A 21 century (re) discovery.
Just an observation.
[I have a couple more weeks to get ready until I leave the country; but thought it was interesting because I brought up clipping also recently]
What can you do along those patent lines with OPS .... SIM first?
THx-RNMarsh
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I haven't seen anything to suggest the amp uses feedforward correction like you said. All I see is a complex feedback design to make high-feedback class B workable.
It was <-118db, not -118db. Really they only said THD would be BELOW that level, they didn't give absolute figures. I don't think there's much point in giving absolute figures anyway because it's going to vary.
Hello Keaton,
When you measure THD and go from 8 ohm to 4 ohm there should be significant change in the measurement (THD should increase) which is not being shown. Going from non bridged to bridged THD mesurements should show an increase in THD.
Regards
Arthur
When you measure THD and go from 8 ohm to 4 ohm there should be significant change in the measurement (THD should increase) which is not being shown. Going from non bridged to bridged THD mesurements should show an increase in THD.
Regards
Arthur
Who cares about what others write for their THD could be right could be wrong, we all know it says exactly nothing about the performance of the amplifier anyway.
We have had well to really good specced amplifiers for decades, all sounding different some good some bad. I am astounded that in this forum with such brilliant minds, we keep on looking at amplifiers in such a narrow perspective.
We have had well to really good specced amplifiers for decades, all sounding different some good some bad. I am astounded that in this forum with such brilliant minds, we keep on looking at amplifiers in such a narrow perspective.
Hello MiiB,
What new discovery do you think needs to be made to make amplifiers sound better that already hasn't been discovered. Does it have a metric or is it a philosophy with no metric.
What new discovery do you think needs to be made to make amplifiers sound better that already hasn't been discovered. Does it have a metric or is it a philosophy with no metric.
I wonder why we keep on making global feedback amplifiers, this course (the CFA thread) has made it clear that the injection of feedback has to be done over less and fewer components,
Is it really necessary to use an input stage to correct errors that are primarily occurring in the OPS..?
I strongly feel that it must be be possible to explore the OPS the a better degree. make shorter FB-loops and correct the errors where they happen. the Genesis-stealth OPS, Different errorsorrection schemes, or some new creative way of correcting errors where they happen, must at least as an intellectual exercise be a primary area to explore.
Damian made a brave attempt on making a non-global feedback poweramp, but came in short when it came to the OPS, running that outside the loop, was not really an option. Also the Danish LC-audio, did some attempts with their THE-END type products, again running the OPS open loop made distortion quite high (ish) and the output-impedance (damping) suffered somewhat.
Were working quite hard, but not really moving...
Is it really necessary to use an input stage to correct errors that are primarily occurring in the OPS..?
I strongly feel that it must be be possible to explore the OPS the a better degree. make shorter FB-loops and correct the errors where they happen. the Genesis-stealth OPS, Different errorsorrection schemes, or some new creative way of correcting errors where they happen, must at least as an intellectual exercise be a primary area to explore.
Damian made a brave attempt on making a non-global feedback poweramp, but came in short when it came to the OPS, running that outside the loop, was not really an option. Also the Danish LC-audio, did some attempts with their THE-END type products, again running the OPS open loop made distortion quite high (ish) and the output-impedance (damping) suffered somewhat.
Were working quite hard, but not really moving...
If the error is caused by the output stage why not correct this error with feedback loop around it making it closed gain equal to +1, this then could be incorporated into a input stage feedback loop.
There is no magic to it it just needs greater complexity and more effort to get right but it is one solution to the problem.
Aha, 'the psychology of numerical appraisal' att. Lawrence Pomeroy, MD of Daimler 1928-1931. IOW, where subjectives fail, be guided by the measurements - even they are lacking.
Hugh
Hugh
Hugh..😉
Pheonix, why don't you give it a go, then there could be a starting point..
THIS is Not in anyway to hi-jack the thread, but maybe to get even better results with CFA style frontends
Pheonix, why don't you give it a go, then there could be a starting point..
THIS is Not in anyway to hi-jack the thread, but maybe to get even better results with CFA style frontends
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I wish it were so simple... Embedding feedback loops is no escape from the maximum feedback theorem.
I have no problems building a poem around an amplifier model, replacing numbers by adjectives. If one is gullible enough to purchase the amp, based on the poem adjectives only, then so be it.
My problem starts when the manufacturers are inserting misleading, or outright fake, numbers in the poem, and then add a dash of pseudo-science to justify them. That is beyond marketing, and qualifies as fraud.
Elektor "Hexfet Amplifier" has this configuration but the output stage has little more than 1.
Years ago I build this one and it had no oscilation. I made a few modifications due use others mosfets. Marvelous sound ! My loudspeakers disapeared!
eD
