That is the low end C338. I am talking about C388.
One review: Review: NAD C388 | Son-Video.com: blog
The C388 was paired with B&W 804D3 and did an excellent job.
But as I said, reference amplifiers is a difficult topic because 1. We are dealing with subjective and biased ideas. 2. Class A, Class AB or Class D. Solid State or Vacuum Tubes .. will all create their own situation and way of measuring. 3. Perhaps the more correct approach is not talking about amps, but pure 1 watt sinewave sweep to measure the loudspeakers frequency response and signature - aka how the whole graph between 10 hz and 25 kHz look - THAT is what matters.
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And while we are talking reference, how about that perfectly flat response curve in a loudspeaker. Almost no one listen or enjoy that and perhaps because in real life, nothing is truly flat.
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Oh sorry. Got my digits crossed.
The NAD388 is a class D switcher...One review: Review: NAD C388 | Son-Video.com: blog
The C388 was paired with B&W 804D3 and did an excellent job.
But as I said, reference amplifiers is a difficult topic because 1. We are dealing with subjective and biased ideas. 2. Class A, Class AB or Class D. Solid State or Vacuum Tubes .. will all create their own situation and way of measuring. 3. Perhaps the more correct approach is not talking about amps, but pure 1 watt sinewave sweep to measure the loudspeakers frequency response and signature - aka how the whole graph between 10 hz and 25 kHz look - THAT is what matters.
- EDIT -
And while we are talking reference, how about that perfectly flat response curve in a loudspeaker. Almost no one listen or enjoy that and perhaps because in real life, nothing is truly flat.
You are eventually going to need a really good amplifier if you want to design really good speakers. There are problems that are way beyond frequency sweep response and simple THD. One step at a time.
Hello fellow dyi audio members, I just recently purchased a near new A-9010 that was dead and not working for $29.00. I repaired it in about 20 minutes by replacing a shorted TO-220 3 terminal +12v regulator and replacing a fuse. After the repair I listened to it for about a week prior to selling it on ebay making a very nice profit. I must say it did sound very nice indeed. Had I know this topic would have come up, I would have measured the distortion so that I could have shared. Just thought I would share the recent experience.
Mickeystan
Mickeystan
Nice of you to jump in on the debate. Yeah that is too bad and I am sure someone are able to measure before I do since I need equipment in my tech-lab.
What made you sell it, out of curiosity ?
I presume it was the need of some odd coloured small paper rectangles with pictures and numbers on it. And probably because there were already some nice other amplifiers in his possession.
Aka valve amplifiers. I have the Morgan Jones book in the bookshelf, when I get some time left over, I will spend time with it.
re post#19
Cherry divided transient intermodulation distortion into hard and soft versions (ref. transient intermodulation distortion part 1 (ieee transactions on acoustics 1981) and part 2 (JAES) 1986. What he referred to as hard is internal clipping of a transistor due to a fast input signal where the feedback is slow due to a dominant pole.
If the input stage is sufficiently degenerated so that it does not clip on a fast signal at maximum amplitude it will not exhibit this hard TIM, or slew induced distortion.
Phase lead compensation also helps in that it provides a relatively fast feedback path rather than slow, reducing the differential voltage between input and feedback at high frequencies, whereas Miller compensation increases the differential.
Stochino published a very fast amplifier using Miller compensation and relatively low degen resistors - but increased the input stage bias current to accommodate a full input signal without clipping.
There is some data suggesting that real music signals do not cause such transient distortions (they are not fast enough due to recording filtering etc). But some early Miller compensated amplifiers of the 1970's really could generate slew induced distortions on moderately fast input signals. Many amplifiers now include an input RC filter to limit the bandwidth which helps.
I take the view that if an amplifier bandwidth is 200kHz - ten times the standard audio range limit - then it is unlikely to suffer from TIM or SID (but needs to be checked).
Cherry divided transient intermodulation distortion into hard and soft versions (ref. transient intermodulation distortion part 1 (ieee transactions on acoustics 1981) and part 2 (JAES) 1986. What he referred to as hard is internal clipping of a transistor due to a fast input signal where the feedback is slow due to a dominant pole.
If the input stage is sufficiently degenerated so that it does not clip on a fast signal at maximum amplitude it will not exhibit this hard TIM, or slew induced distortion.
Phase lead compensation also helps in that it provides a relatively fast feedback path rather than slow, reducing the differential voltage between input and feedback at high frequencies, whereas Miller compensation increases the differential.
Stochino published a very fast amplifier using Miller compensation and relatively low degen resistors - but increased the input stage bias current to accommodate a full input signal without clipping.
There is some data suggesting that real music signals do not cause such transient distortions (they are not fast enough due to recording filtering etc). But some early Miller compensated amplifiers of the 1970's really could generate slew induced distortions on moderately fast input signals. Many amplifiers now include an input RC filter to limit the bandwidth which helps.
I take the view that if an amplifier bandwidth is 200kHz - ten times the standard audio range limit - then it is unlikely to suffer from TIM or SID (but needs to be checked).
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john_ellis: Thanks, sound like something I want to read up on. Regarding clipping which is an issue in general, the only thing I have stumbled upon so far with my limited research is creating a class A+AB amplifier and I like the theory behind it. Class A is always on so low signals will pass but it is very inefficient. Class AB switches and is more efficient but can produce clipping at low voltage signal input. By allowing the transistor to sit just at the on state voltage it is barely on which is enough to prevent clipping.
February | 2013 | The Signal Path
February | 2013 | The Signal Path
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