31–40 of 49 posts
I'm both an IT and audio geek, does HN likes audio geekery? I'm not affiliated with the company behind this website BTW..
> does HN likes audio geekery Only if scientifically backed.
There are quite a few very, very good class D amplifier designs out there. “Very good” means highly efficient and with good enough fidelity (noise, distortion, etc) that no one will ever be able to distinguish them from perfect. But, IMO quite annoyingly, these things generally have analog inputs. This means you need a good DAC (which exists and isn’t terribly expensive) and a good connection from the DAC to the amp.…
Given that it's just phase-correct PWM, you'd think feeding the bits you'd stuff into a DAC directly into the PWM counter would do the job nicely. You could probably do that with a fast microcontroller these days. Some golden-eared audiophool pillock would complain they could hear jitter caused by the pins not being gold-plated or something, but who cares?
The good class D amplifiers are closed-loop control systems. They don’t just create a output a fixed sequence of highs and lows for a given piece of music — they determine when to switch based on some combination of the input signal, the observed output voltage and current, and various state variables (for example, for protection). And they operate at frequencies of several megahertz, possibly with rather high precision pulse widths needed.
So one could do this with an ADC, a microcontroller, and a single output bit, but it would need to run the ADC at quite high frequency and possibly have multiple input channels (for current and voltage). This sounds expensive.
A TPA3255 costs $12.50 (qty 1 from Digikey). Add a dollar or two a nice DAC. I don’t think a 20-bit ADC, a DSP running at a couple hundred MHz, and most of the same driver and power circuitry that’s already in the TPA3255 would come out at the same price.
There are quite a few very, very good class D amplifier designs out there. “Very good” means highly efficient and with good enough fidelity (noise, distortion, etc) that no one will ever be able to distinguish them from perfect. But, IMO quite annoyingly, these things generally have analog inputs. This means you need a good DAC (which exists and isn’t terribly expensive) and a good connection from the DAC to the amp.…
Searching for "plate amplifier module" you can find integrated digital/amp/crossover units suitable for DIY builds.
Earlier quoted context omitted.
Given that it's just phase-correct PWM, you'd think feeding the bits you'd stuff into a DAC directly into the PWM counter would do the job nicely. You could probably do that with a fast microcontroller these days. Some golden-eared audiophool pillock would complain they could hear jitter caused by the pins not being gold-plated or something, but who cares?
It takes a lot of computing power to reconstruct an audio sample well. Once reconstructed it takes massive massive amounts of storage. It's all about the Shannon Nyquist sampling theorum. "Strictly speaking, the theorem only applies to a class of mathematical functions having a Fourier transform that is zero outside of a finite region of frequencies. Intuitively we expect that when one reduces a continuous function t…
It does not take a lot of computing power, but it does take a couple of opamps.
Too bad it's not actually DIY. Does anyone remember the 80s-era catalog of DIY HiFi kits? I can't remember the name, it was electronics geek+audiophile porn. Maybe it was Craven? something like that?
Crutchfield? https://en.wikipedia.org/wiki/Crutchfield_Corporation
The catalog I'm recalling was cover to cover populated amplifier circuit boards accompanied by specs and prices. Lots of huge toroidal transformers... maybe it was a local thing back in IL.
The cover was mostly black with glowy green text IIRC, nothing like the vintage Crutchfield catalogs I can find via GIS/ebay. Oh well.
Don't see the point of this when I can just build a Kevin Gilmore Dynalo or Dynahi. Very low part count, almost BOM golf like; multiple variations by him and others to cover any case. Closest you will ever get to a wire with gain. Not to slight Hypex (the company behind the Ncore family of Class D chip amps), mind you, they're probably the only chip amp to ever succeed in making low distortion high output high effici…
Earlier quoted context omitted.
Crutchfield? https://en.wikipedia.org/wiki/Crutchfield_Corporation
They seem too focused on automotive/car stereos to be it. The catalog I'm recalling was cover to cover populated amplifier circuit boards accompanied by specs and prices. Lots of huge toroidal transformers... maybe it was a local thing back in IL. The cover was mostly black with glowy green text IIRC, nothing like the vintage Crutchfield catalogs I can find via GIS/ebay. Oh well.
Earlier quoted context omitted.
They seem too focused on automotive/car stereos to be it. The catalog I'm recalling was cover to cover populated amplifier circuit boards accompanied by specs and prices. Lots of huge toroidal transformers... maybe it was a local thing back in IL. The cover was mostly black with glowy green text IIRC, nothing like the vintage Crutchfield catalogs I can find via GIS/ebay. Oh well.
Possibly Madisound. Their site says they've been around since '72. I have vague recollections of them having a print catalog in the 90s before everything went online.
https://www.ebay.com/itm/255457806571
That cover seems very familiar to me, and I do remember there being a bunch of green on a black background.
There are quite a few very, very good class D amplifier designs out there. “Very good” means highly efficient and with good enough fidelity (noise, distortion, etc) that no one will ever be able to distinguish them from perfect. But, IMO quite annoyingly, these things generally have analog inputs. This means you need a good DAC (which exists and isn’t terribly expensive) and a good connection from the DAC to the amp.…
edit: My mistake. When I first read your post I thought you said there were quite few as opposed to quite a few good designs, hence the recommendation.