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Build Your Own Professional-Grade Audio Amp on the Sort-Of Cheap

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Re: Build Your Own Professional-Grade Audio Amp on the Sort-Of Cheap

#141

Post by foobarian »

scblock wrote: post #135
milesvp wrote: post #50

Earlier quoted context omitted.

I'm not convinced audio engineers are having that argument anymore (which is more the audience of IEEE). I get the impression from an engineer I know who's specialized in digital signal processing, and who's done a significant amount of analog work, that anyone who's still having some of these arguments doesn't understand some of the basic maths of the problem space. That basically, you can always digitally encode an…

Amplifier designers most certainly are. Class D has significant energy efficiency advantages, and significant sonic challenges. It’s taking an analog waveform, whether decoded by a DAC or starting as pure analog, and chopping it into a series of pulses (pulse width modulation). The amp is switching transistors on and off very quickly, rather than using them as a variable linear gain stage. It’s not the same as PCM en…

The energy efficiency advantages in class D are incredible. When my old Technics receiver stopped working because it started overheating, i replaced it with a class D amp on a half-credit card sized circuit board from dx.com and taped it to the back of the TV. 20W per channel, which is plenty for my casual TV watching. The Technics was the size of several stacked pizza boxes, with fans and heat sinks etc.

Re: Build Your Own Professional-Grade Audio Amp on the Sort-Of Cheap

#142

Post by mnemotronic »

{quote} ... I connected it to a pair of 30-year-old, three-way Panasonic speakers, which I frequently use for testing.{/quote} Ummmm. I'm tempted to dismiss the author's entire project based on that. Why not use a pair of decent speakers or some high-end headphones like the Stax electrostatics or Audeze planars? Weakest link in the chain and all that.

Re: Build Your Own Professional-Grade Audio Amp on the Sort-Of Cheap

#143

Post by sjwright »

S_A_P wrote: post #123

Audiophilia is a study in contradiction. The ask is a flat "uncolored" accurate sound. The gear that sells for ridiculous prices is usually tube gear with limited bandwidth and makes ~15 watts at 5-10% (admittedly usually even order harmonic) thd. Hardly uncolored. That said, and Ive mentioned this before on HN. My (now late) uncle had a bunch of audiophile friends in Dallas. He hung around folks who had spent upward…

The three critical paths for high end sound reproduction are: loudspeakers, speaker placement, room acoustics. Of course all parts of sound reproduction matter, but those three are the ones that affect real systems in practice.

Most other factors are rarely an issue and/or inferior parts have a much lower magnitude of impact on sound quality. Sufficiently good source material (256kbps AAC or better) is widely available. Most amplifiers are fine. Almost all wire/cable is perfectly good. High quality DACs are more abundant than you might think (e.g. the digital inputs of any half-decent AV receiver made in the past decade).

Good speakers.

Good placement.

Good acoustics.

Those are the ones to focus on. They're the ones to spend money on. If you wanted to add a fourth to that list, I'd add an honourable mention to in-room calibration systems like Audyssey and DIRAC. Depending on the sorts of imperfections in a given system the opportunity for improvements with DSP might be substantial and dramatic, or marginal to the point of being irrelevant. (For most systems it's somewhere in the middle.)

Re: Build Your Own Professional-Grade Audio Amp on the Sort-Of Cheap

#144

Post by MrTonyD »

mrob wrote: post #75
MrTonyD wrote: post #56

I'm probably the only one with this opinion...but I sure miss the old days of tube amps that weren't able to be highly accurate. They would roll-off the on the high end, distort a bit all over, and gave a very warm and relaxing feel to the albums I played obsessively. Now I've owned high-end tube and solid-state gear, and the music hasn't sounded good for decades. Combine that with the very limited bits provided by C…

>Combine that with the very limited bits provided by CDs, preventing any possibility of good playback 16 bits gives you 96dB SNR (and subjectively more with dithering), which is plenty at non-deafening listening volumes. It's more than even the highest quality vinyl ever had. High bit depth is mostly useful so you've got some headroom during editing.

That is absurd. Anybody who has read about the history of CD bit depth would know just how absurd that is. And I even personally investigated CD accuracy in burning using an electron microscope to understand how the laser burning process worked on the plastic media. It was absurdly inaccurate. All these claims about how great digital is are just crazy - claims made by people who are relying on old data about hearing accuracy and a religious faith in technology. Anybody who has actually designed instruments using the known laws of physics understands the incredible limitations - and those limitations apply to both characterizing hearing as well as reproducing sound digitally.

Re: Build Your Own Professional-Grade Audio Amp on the Sort-Of Cheap

#145

Post by sjwright »

syntaxing wrote: post #76
korethr wrote: post #6

Earlier quoted context omitted.

I thought of the same thing. Both are inexpensive, straightforward, no-BS projects that leverage the advances made in electronics over the years to deliver quality audio. If I made one of these, I 'd be tempted to put an ODAC and O2 board in the same chassis to have a complete amplifier.

Hearing the ODAC name is quite a throw back! I remember reading NwAvGuy's blog when I first started getting into headphones. I always wondered what happened to him.

Given the way he suddenly went to radio silence, I just assumed he was hired by Apple...

Re: Build Your Own Professional-Grade Audio Amp on the Sort-Of Cheap

#146

Post by ddingus »

albertgoeswoof wrote: post #27
fermienrico wrote: post #16

It is refreshing to see these types of articles. Of all disciplines of human interests and hobbies, Audiophiles are one of the most stubborn, misinformed, anecdotal and delusional bunch. Of course I am generalizing, but every time I engage in a discussion about audio quality, it is a losing battle. Not because of lack of data or supporting evidence, but because of the fundamental dissent for data driven arguments. Yo…

Nothing wrong with vinyl, that’s more about physically handling the media, reading the sleeves, listening to an album the whole way through etc. Than the audio quality. No vinyl enthusiast would say the quality is objectively better, but the experience arguably is

Bingo.

And what I often crave is the less accurate vinyl sound, that coupled with different production values.

Not better, just resonant with me. Easiest way to explain it.

Re: Build Your Own Professional-Grade Audio Amp on the Sort-Of Cheap

#147

Post by ddingus »

mbell wrote: post #89
fermienrico wrote: post #29

Earlier quoted context omitted.

Yea, I removed the Vinyl argument. That's for another time. Nothing wrong with Records but I've had the same issue talking to people about Records wrt to audio quality. I own Records and like you, I enjoy the experience. There is something amazing about listening to the entire album without distractions and in the sequence that the artist intended. You could do this with mp3/CD, but Records get me in the right mood :…

There are objective reasons to favor vinyl even today. The 'audio quality' if measured in terms of SNR is objectively much worse than any modern medium, however the mixes used for vinyl tend to not be compressed to death so the dynamic range can offset this shortcoming.

Yes

Re: Build Your Own Professional-Grade Audio Amp on the Sort-Of Cheap

#148

Post by sjwright »

scblock wrote: post #135
milesvp wrote: post #50

Earlier quoted context omitted.

I'm not convinced audio engineers are having that argument anymore (which is more the audience of IEEE). I get the impression from an engineer I know who's specialized in digital signal processing, and who's done a significant amount of analog work, that anyone who's still having some of these arguments doesn't understand some of the basic maths of the problem space. That basically, you can always digitally encode an…

Amplifier designers most certainly are. Class D has significant energy efficiency advantages, and significant sonic challenges. It’s taking an analog waveform, whether decoded by a DAC or starting as pure analog, and chopping it into a series of pulses (pulse width modulation). The amp is switching transistors on and off very quickly, rather than using them as a variable linear gain stage. It’s not the same as PCM en…

> Amplifier designers most certainly are.

Amplifier designers have to sell to a market that is rife with misinformation and a very poor signal-to-noise ratio between technical quality, profit margins and overall market success. I wouldn't expect many of them—especially the ones who have any name recognition—to be concerning themselves with objective technical performance.

Whereas the guy who designed the amplifier circuits for a product where the customer isn't being placeboed by the spec sheet—like powered studio monitors, or consumer devices like the Apple HomePod—is far more likely to be focusing on objective measurement rather than faulty market perceptions.

Re: Build Your Own Professional-Grade Audio Amp on the Sort-Of Cheap

#149

Post by mrob »

MrTonyD wrote: post #144
mrob wrote: post #75

Earlier quoted context omitted.

>Combine that with the very limited bits provided by CDs, preventing any possibility of good playback 16 bits gives you 96dB SNR (and subjectively more with dithering), which is plenty at non-deafening listening volumes. It's more than even the highest quality vinyl ever had. High bit depth is mostly useful so you've got some headroom during editing.

That is absurd. Anybody who has read about the history of CD bit depth would know just how absurd that is. And I even personally investigated CD accuracy in burning using an electron microscope to understand how the laser burning process worked on the plastic media. It was absurdly inaccurate. All these claims about how great digital is are just crazy - claims made by people who are relying on old data about hearing…

>I even personally investigated CD accuracy in burning using an electron microscope to understand how the laser burning process worked on the plastic media. It was absurdly inaccurate.

I can believe that, but the standard was designed to tolerate high bit error rates. 25% of the bits are redundant, as part of a error correction code:

https://en.wikipedia.org/wiki/Cross-interleaved_Reed%E2%80%9...

This scheme works very well, as proved by people consistently ripping bit-for-bit identical copies of CDs pressed or burned with the same audio.

Re: Build Your Own Professional-Grade Audio Amp on the Sort-Of Cheap

#150

Post by mrob »

TylerE wrote: post #133
lelandbatey wrote: post #103

Earlier quoted context omitted.

Your statement that CDs have a very limited number of bits is false by every known objective measure (compared to any prior consumer analog medium). CDs afford a bit depth of 16, while tape provides at most 6, and vinyl at most 12. See this great video by signal engineers for more info: https://xiph.org/video/vid2.shtml I suspect this is a classic case of "you think you want X, but what you actually want is your yout…

Your statements about tape and vinyl are ludicrous and unsourced. What do you think most of your CDs were recorded on in the first place? (Hint: tape)

The 6 bits worth of SNR (36dB) for tape does sound implausibly low, even for consumer grade compact cassettes. And professional 1/2" reel-to-reel could do substantially better, although still worse than CD quality.
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