Patrick,
Both should be transparent so get a check for audio competence. It then boils down to which design is most efficient in terms of weight, cost and energy use.
Conceptually, a non-constant distortion amp could colour sounds differently at different frequencies, but the level of overtones produced by these two amps are way below the level that can be detected by ear.
I wish I could hear any level of distortion @ 10kHz and would be most impressed by someone who could.
Both should be transparent so get a check for audio competence. It then boils down to which design is most efficient in terms of weight, cost and energy use.
Conceptually, a non-constant distortion amp could colour sounds differently at different frequencies, but the level of overtones produced by these two amps are way below the level that can be detected by ear.
I wish I could hear any level of distortion @ 10kHz and would be most impressed by someone who could.
> a non-constant distortion amp could colour sounds differently at different frequencies
That is only true if the signal amplitude is constant throughout.
But usually the signal content at say 10kHz is lower than at 1kHz, not true ?
Patrick
That is only true if the signal amplitude is constant throughout.
But usually the signal content at say 10kHz is lower than at 1kHz, not true ?
Patrick
I don't think you can dispute that an amp with constant THD across frequency is less transparent than an amp with the same THD at high frequencies but lower at lower frequencies.
That said, a few considerations: is it audible? If it is all below 80dB, I don't think it is (assuming controlled testing).
If for some reason it is desired, what price is there to pay? There may be repercussions in the transient and/or overload recovery behaviour.
So, although the answer is relatively straight forward, whether you want one or the other already moves into the area of personal opinion and view.
I know, this is not helpful. Sorry.😱
Jan
That said, a few considerations: is it audible? If it is all below 80dB, I don't think it is (assuming controlled testing).
If for some reason it is desired, what price is there to pay? There may be repercussions in the transient and/or overload recovery behaviour.
So, although the answer is relatively straight forward, whether you want one or the other already moves into the area of personal opinion and view.
I know, this is not helpful. Sorry.😱
Jan
In this context competent could be a matter of opinion. IME I have not seen a test that isolates completely just the harmonic structure.
BTW speaking of constant THD I've stuffed the RIAA boards and other than my followers needing snubbers everything looks better than good 1 -2% matching on everything high 90's on THD at mid-level .01% at full line level. Tomorrow I will try to get some nice cast enclosures for everything.
I'll be sending an update soon and will post an update probably in Bill's phono thread.
> will post an update probably in Bill's phono thread.
Why not update here since you post the original circuit here already ? 🙂
Patrick
Why not update here since you post the original circuit here already ? 🙂
Patrick
> I don't think you can dispute that an amp with constant THD across frequency is less transparent than an amp with the same THD at high frequencies but lower at lower frequencies.
You meant the latter is more transparent ?
Patrick
You meant the latter is more transparent ?
Patrick
Do you mean harmonic distortion? If IM distortion, with tones at 10kHz and 11kHz, what about a difference product at 1kHz?
I prefer constant distortion over frequency like the original Otala amp. I don't always achieve it as well as I would like. I rely too much on negative feedback most of the time.
That's how I read it. And the latter will assuredly have lower IMD throughout the audio band. But, arguably, if both are outside of audibility, the design criteria should move aggressively towards addressing large signal nonlinearities. (To paraphrase/restate recent opinions)
I don't know what is wrong with you guys, but Jack did not 'invent' BQP products in his garage. He gets them from outside, somebody big, and only adds connectors and stuff to make them useful for audio.
John, that just reads more and more like conspiracy theory stuff. Someone "big" is patently non-falsifiable. The entire topic of BPQ's is described in a way that is carefully non-falsifiable. That's a huge huge HUGE red flag.
Constant distortion with frequency implies constant feedback with frequency which is usually caused by deliberately high open loop bandwidth. High open loop bandwidth, all else being equal, usually gives lower PIM distortion. So there! '-)
Probably so, except for a recent trend to mix music with a very bright sound. Rather than volume falling off with rising frequencies, volume is made constant across the audio band. Therefore, a lot more high frequency energy is present to intermodulate.
Also, whether or not there is more or less IMD throughout the audio band is a separate question from how objectionable the IMD may sound with different types of source material.
for my money I prefer a Low and flat thd vs frequency versus a very Low but rising.
Bruno putzeys makes the same observations in his feedback article and in this one: https://www.diyclassd.com/img/upload/doc/an_wp/WP_AES123BP_the_engineers_survival_guide.pdf
Bruno putzeys makes the same observations in his feedback article and in this one: https://www.diyclassd.com/img/upload/doc/an_wp/WP_AES123BP_the_engineers_survival_guide.pdf
Attachments
Oh, I don't know, RNM recently claimed to have obtained special gas-filled rings to increase the maximum compression ratio of a car engine. And he apparently got the things from what might be described as "somebody big."
In addition, sometimes companies have trade secrets and intentionally don't provide detailed information for that reason. Having said that, I don't know if the things being talked about ever do anything at all as I haven't tried them.
Here is an interesting device that doesn't provide a lot of detailed verifiable information about how it works, yet is does work quite well. One can only listen to find out exactly how well: Recoil Stabilizers | Primacoustic I paid more for those things that I did for the NS-10 speakers I use with them. And they are worth every penny.
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