According to many magazine reviews. Of course, you would have to ask each of the magazine reviewers around the planet your question.
but, I am sure the consensus was always done under the most rigorous of scientific test methodology. So, no fear - the HF LP filter is a contributor.
THx-RNMarsh
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Probabaly the DAC and its shifting effects of noise and distortion/artifacts above 20KHz. This is simply measured at the analog output of CD players.
It does not hurt anything to have HF filtering on both types. but usually isnt done on either type. Or not low enough freq to matter.
The CFA amp is linear and fast enough (SR) to have little distortion at HF freqs. Not so with VFA with increased distortion as fb is reduced at HF.
This is the topology of my choise today and variations of it.
View attachment 799631
BTW -- All M. Levenson amps/preamps have been band limited since forever. A key contributor to why they sound better in most systems.
Originally, put there to prevent triggering TIM, but now useful to remove digital artifacts, also.
You're welcome.
Sorry, I'm not buying.
The CD player output noise could have lots of root causes, a bad SMPS, bad wiring, mains noise, AM station ingress, loop ground between the DAC and the instrument, etc... This is by no means a typical DAC, but rather a pathological one (or it's setup, thereof).
CFAs don't provide any extra linearity at HF compared with any other topology. You are probably thinking of a high ULGF (allowing more loop gain at HF), which is by no means not specific to the CFA topology. You already found out what is the possible result of pushing the (power audio) ULGF to warp speed values.
I'm not aware of any competently designed amplifier that doesn't have some sort of HF bandwidth limitation at the input. Those that don't once again qualify as pathological implementation an canot, by any means, be considered as typical or representative.
Slew rate has a) nothing to do with distortions, provided it is high enough to avoid large signal slewing distortions (and the rule of thumb for slew rate in audio already has a 10x coefficient) and b) it is not attainable by CFAs only, VFAs with 100's of V/uS slew rate are pretty common.
I'm not expecting to get you out of your CFA trench, but just to set the record straight.
Bob Cordell got the same number in his VFA, published in JAES in 1984. He attributes it to using a different compensation scheme, not Miller-effect pole splitting in the second stage.
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Oh you mean that CFA with buffer on - input = VFA? Yeah that works good also.
An easy 8 Ohms and only 50W? Really? That isnt good enough for my system requirements.
Whats the distortion above 20KHz? Unless, you missed the message, the issues are from above 20Khz and not < 20KHz.
-RNM
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Nope just various regular players everyone has. stock units. yep typical of many.
The rest of your pronouncements ...... Nice try.
THx-RNMarsh
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So, in your logic, a bad DAC (regular, stock, typical, to quote you) is a good reason the get a CFA power amplifier. And not a decent DAC, of course. Very interesting logic.
I'm looking at the stereophile reviews and can't see anything amiss up to 100kHz from anything currently available.Above that really should be filtered out. Or am I missing something
BTW -- All M. Levenson amps/preamps have been band limited since forever. A key contributor to why they sound better in most systems.
Do people consider the recording part of the system?
Nothing. Everybody knows that hifi systems are not designed to play music in a believable and harmonious way, but to reach impressive numbers. The pity is, here too, you will have a problem. With your eyes turned off, by dint of refusing to use them, you will need help to read those numbers.
I'm not talking about understanding their means, of course, with the harm you seem to have in understanding the post you're responding to.
In this regard, what is your problem with odd harmonics? Guitars and brass produce a lot, and the most beautiful jazz chords are based on their use. Even harmonics are monotonic.
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You didn't say "According to many magazine reviews" on that post.
BTW, which magazine published that Levenson amps/preamps, "A key contributor to why they sound better in most systems" is due to "All M. Levenson amps/preamps have been band limited"?
Here is an example of Levinson amp (expensive) compared with Yamaha integrated amp (relatively cheap). No audible difference. How about that.
Do you kindly understand where RNMarsh is coming from?
Then what way are they designed to play?
What are some examples of those numbers? Lets see some.
What about listening to sound replaying system? Would you have something to say about "eyes turned off" to those who say to "trust your ears"?
When did I get removed from your ignore list? Would you mind announcing it when you do? Thanks.
Doesn't explain everything. I posted measurements and indeed even maths, that proved a very powerful point. It got ignored? Worse than that, it was pilloried. Then later I was accused of not posting measurements, then I strongly objected that I had and I re-posted them. This time I got some response and I noted that Scott had taken notice and starting to ask the correct questions, namely what I call the "0.1dB" challenge (I believe Scott knows what I am referring to) and acoustic measurement to further corroborate. I have been keeping that in mind and I will get back to him on that.
I believe what we are seeing is people putting ego before the "feelings" of others. At that point much gets lost in translation.
Just my Penny's worth.
PS: The "0.1dB" challenge is that a current change in dBSPL of a driver, its acoustic output measurable in dB level, between the driver being driven by a voltage sources versus a current source, the change is both measurable and calculable and they correspond. I had rounded the results, backed up by maths based on a variable Vre, to 1dB. Scott has asked if it is accurate to 0.1dB and I believe it is. If it is, then it proved that any impedance above the the DC, or Re, the resistance of the voice coil, is an actual impedance. It is a "back-EMF impedance" - a term that has become controversial to use here and I did not realise that it was, until Chris Anantech kindly explained it to me in a PM that it was putting people here off-side. That surprised me. Yet in the circles I move, the term did get accepted because the measurement shows it is and so does that maths.
On Blowtorch I was even confronted by someone saying that "even if may look like an impedance, it does not mean it is an impedance." For the sake of ego, an irrational argument like that was framed? Apparently so.
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I would appreciate it if you can quote my post which showed such claim or implied. It should be easy to show since you stated that it's a fact. I'll hold my breath for this one.
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