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In Reply to: RE: Halcro can sound OK.... posted by Ivan303 on October 08, 2015 at 19:10:50
And Halcro isn't a switcher!
It does, however, rely upon "immodest" amounts of corrective feedback.
Follow Ups:
as it claims to draw only 350 watts from the wall while producing 250 watts to the speakers.
Certainly not class A!
OK, the Halcro dm58 may not be, but the MC20 pictured above is.
I've heard an amp from the DM series (in an exceptional system and was not impressed), but was not aware they offered an entry level amplifier.
So we have ultrasonic noise inherent in Class D amps and ultrasonic noise in the DSD noise shaping process for DSD file playback.
Makes me say hmm, as I sit back and think to myself why go through all of that when we have tried and true Class A/AB amplification and hi-res PCM files that sound absolutely wonderful.
I must still assert that there is no good reason for Class D amplification unless: 1) Efficiency is a requirement and 2) Stellar performance can be achieved at a lower cost than traditional designs.
Really need to get out More... Mate,
OR perhaps stop shopping/reading the shill 'magazines'.
I have a Bespoke/diy lm3886 Amp. Yup a simple stoopid chip amp.
http://www.neurochrome.com/modulus-86-rev-2-0/
(albeit using a Cap /tx ps supply) that Has shamed (and permanently replaced) My meshplate 2a3 amp at driving MY Tannoy GRFs.
Bass impact/dynamics that my neighbors can enjoy :-) and highs that are magical.
Cheapish too.
Don't get your "chip amp" confused with Class D switching amps, which is what we are discussing here.The LM3886 is not a Class D switching amp. It's a power Op-Amp and based on the spec sheet graphs for power output vs device heat dissipation, its probably running Class AB.
What you have there mate is an Op-Amp.... with tons of negative feedback. But negative feedback for outstanding "specs" is another topic entirely.
Edits: 10/11/15 10/11/15
Beat a low watt tooby ? That i can believe ......
I've heard many a DSD based recording that sounded naturally "live" and did not possess that artificial leanless you find with switchers. And likely Class D amps are just fine for the majority of folks since they teem with definition and work great at the low end of the market.
They need a bit more time in the oven with folks using their ears for evaluation rather than their eyes. :)
"So we have ultrasonic noise inherent in Class D amps and ultrasonic noise in the DSD noise shaping process for DSD file playback."
All digital audio playback has ultrasonic noise. Or what I'd call radio-frequency interference (RFI).... The problem is the higher the resolution/sample rate, the higher the noise/RFI emissions. I think this could be why I can't listen to high-rez playback for extended periods of time.
I once auditioned some NuForce amplifiers, whose switching cause so much interference, it drowned out the entire FM band with white noise. (The amps otherwise sounded decent.) I'm using an inexpensive Class T amp which doesn't emit such noise, but it's doesn't come close to good tube amplification.
"Makes me say hmm, as I sit back and think to myself why go through all of that when we have tried and true Class A/AB amplification and hi-res PCM files that sound absolutely wonderful."
It's always something to try..... I tried it, didn't like it.....
"I must still assert that there is no good reason for Class D amplification unless: 1) Efficiency is a requirement and 2) Stellar performance can be achieved at a lower cost than traditional designs."
I have a Samson Servo 260 solid state amp..... A cheap amp (but discontinued, and the new stuff isn't nearly as good) that was 90 percent of a Symfonia Opus 10.... I've yet to hear any switching amp I prefer over it.
I admit some of my dislike for RF noise emitting electronics might be psychological..... But why use electronics that emit RF noise where there stellar performance can be achieved by electronics that don't do this? (Not to mention the potential for neighbors wondering why their radio reception has suddenly gone awry..... )
If there is RF noise that does not correspond to the audio signal that was originally recorded, it is because the DAC is poorly designed. It should generate no RF noise of its own. To the extent that this is physically unavoidable by the digital process, then there should be analog filtering between the converter circuits and the analog outputs of the DAC.
However, you are correct. Most DACs do put out a lot of RF crap. Miksa on Computer Audiophile has some RF spectrum plots that demonstrate this. This is the result of poor (or ignorant) engineering.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
"If there is RF noise that does not correspond to the audio signal that was originally recorded, it is because the DAC is poorly designed. It should generate no RF noise of its own."
If that's the case, then just about every DAC ever made is "poorly designed"...... I've yet to encounter a DAC that emitted RFI at low enough levels to where I couldn't notice any interference whatsoever from a radio placed next to it.
Heck, if a piece of gear like that did exist, I'd own it. Provided it isn't hideously expensive.
(Seymour Ice Block Amplifiers - I use one of these, the model 10001. for my subwoofer.)
I've also got an older PS Audio GCC 250 which I still use to this day for my FR and FL speakers.
I can't speak for others, but I'd be shocked if I didn't notice an adverse effect on listenability over extended periods of time. (I'd also be shocked if I were to place an AM or FM radio near the amps, and didn't notice any compromise to reception.)
I had an early pair of NuForce monoblocks placed in a rack near my Hi-Def CableTV box. If I turned the NuForce amps ON, a handful of TV channels wouldn't come through. No snow, the channels were completely blocked. This was a cable box that got a solid direct signal feed over RG6U coax from the cable company, yet the NuForce amps managed to kill a few TV stations.
It was explained to me that the RFI wasn't radiating out of the amplifier enclosure but back through the AC power cord acting as an antenna. NuForce eventually reduced the problem. This was over a decade ago but I'm sure RFI is still a concern that all Class D amp makers have to deal with in one way or another. These amps are power oscillators after all. You'd never have oscillations in a Class A/AB amp unless it was defective.
All my "radio" listening has been over the internet for years. (Well, except in my car!)
Absolutely. IMHO, if Class D can out perform other amps in that sub $2000 +/- range, I'm all for it and it makes good sense. What I don't get are Class D amps selling in the $10,000 +/- range. Class D is not inherently expensive to implement so they should also be 'cost efficient' and priced accordingly. But that's just how my mind works, and some will take issue with that. ;-)
Well PS Audio tried and went back to a ClassA/AB hybrid design ...
A lot of the expense is probably in order to try and recoupe R&D money. I'd expect some of the better designs take a bit of fiddling. A buddy at work hooked me up with the UCD simulations for LTspice. Those things are a technological marvel in many ways whether people like the way they sound or not.
| Absolutely. IMHO, if Class D can out perform other amps in that sub $2000 +/- range, I'm all for it and it makes good sense.That's why I use it.
I wouldn't want to spend $10,000 on an amplifier---I'd rather upgrade speakers or take a vacation.
The increase in efficiency drives cost tremendously --- far smaller case & heat sink & power supply needed. And I do care about power consumption and heat and having less of a huge mass in cabinet.
Additionally, the power cost to keep it running continuously is low, and so it's always warmed up and sounding its best, and I may only have time for quick listens. And I can plug it into the passive power conditioner/cleaner.
So for me, the higher efficiency is a multi-faceted major win, and now the class D sonics are in general, as good as typical solid state amplifiers of similar cost & power.
Edits: 10/09/15 10/09/15
and being a 'Utah Triodes and Horns Guy' we used to enjoy going to CES and noticing how BAD Wilson's biggest and baddest speakers always sounded.
Must admit that driving the Avalon's in a smaller room they disappeared and let the music flow.
And that while listening to vinyl.
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