Build Your Own Professional-Grade Audio Amp on the Sort-Of Cheap • Hacker News Board

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

#181

Post by Steve44 » Thu, Nov 01, 2018, 10:32 AM UTC

rubatuga wrote: post #33

If you just want the amp without building it, you can get a TPA3116 Class D amplifier. It is only $21 USD from aliexpress (with free shipping of course!). It accepts a supply voltage of up to 24V meaning that you can just dig around for your old laptop power supply (19V). It comes with a nice and sleek aluminum case, and has low enough noise floor that I can't detect it at all unless my ear is right up against the sp…

I know this isn't what the original article is about but for quite some time I used a Topping TP31 amp, it's the same technology you are talking about.

It's not the best amp I've had, it's not loud enough for parties, or even very loud music, and it doesn't drive my planar headphones well.

What it does do is easily fill my home/office room well above comfortable working & listening level, it drives my Sennheiser headphones pretty well, it's cheap & small and it just works.

For what it is, it's brilliant.

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

#182

Post by Steve44 » Thu, Nov 01, 2018, 10:44 AM UTC

smcameron wrote: post #126

irrational wrote: post #26

Earlier quoted context omitted.

I have some questions. My son has been taking guitar lessons using a classic guitar. Using the advice of his instructor we are getting him a begginer's electric guitar for christmas. We also need to get him an amp. Is the amp in this article the same kind of amp that you could plug an electric guitar into? I know nothing about music or instruments, but I do know about electronics so I was thinking it might be fun to…

Short answer: No. Guitar amps are weird, not like hi-fi amps at all. In a hi-fi amp, distortion is the enemy. In a guitar amp, distortion is sought after. Driving the pre-amp section of a guitar amp into clipping is extremely common and desirable . Doing the same with a hi-fi amp is not . A hi-fi amp will be typically connected to speakers with a woofer and a tweeter and maybe a mid-range, trying to accurately reprod…

> A guitar amp is literally half the instrument.

I'm not a musician and this confused me for some time. I'd see electric guitars with their own amp & speakers then a microphone for the the PA system in front of said speaker. I couldn't understand why the electric guitar wasn't just plugged in, something I read a few years ago was a light-bulb moment.

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

#183

Post by archi42 » Thu, Nov 01, 2018, 10:45 AM UTC

rubatuga wrote: post #33

If you just want the amp without building it, you can get a TPA3116 Class D amplifier. It is only $21 USD from aliexpress (with free shipping of course!). It accepts a supply voltage of up to 24V meaning that you can just dig around for your old laptop power supply (19V). It comes with a nice and sleek aluminum case, and has low enough noise floor that I can't detect it at all unless my ear is right up against the sp…

Oh, that one looks neat. I've got another Ali module with integrated Bluetooth for use in my study room. Theoretically the parts have decent specs, but the module has a high noise level and the speaker makes a loud popping sound with a lot of movement on power on :(

Maybe I'll replace it with the amp you linked :)

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

#184

Post by S_A_P » Thu, Nov 01, 2018, 10:46 AM UTC

scns wrote: post #170

sjwright wrote: post #143

Earlier quoted context omitted.

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 availab…

The weakest "link" in the "audio-chain" (if you exclude the room) are passive speakers with distortion above 1% The best speakers i heard to date are from a german company called Backes & Müller. Active crossovers, each speaker has its own poweramp and a sensor attached to the membrane. The signal of the sensor is fed back into a comparator which calculates the difference to the music signal, this is then used to for…

Those look intriguing. I would like to hear them. One of the things I’ve lamented as time and technology march on is how high fi seems to have lost it’s mainstream appeal. It seems like when I was growing up there was a wide continuum of commodity grade to mid grade to prosumer to high end gear available. There was always ridiculous high end stuff but even companies like Sony pioneer and technics had a higher end line. Then there were the smaller companies like adcom, carver, McIntosh, etc that had a reasonably large product line. Now it seems that it’s just commodity or niche boutique gear. Most of those companies still exist, but with a far smaller product assortment or they were absorbed into an audio conglomerate like harmann and badge engineer from some other product line.

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

#185

Post by mnw21cam » Thu, Nov 01, 2018, 10:47 AM UTC

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)

Yeah, my brother worked in a fairly antiquated recording studio about 10 years ago, and they had 24-bit 96kHz ADCs right next to the microphones, with digital lines carrying the sound data to be recorded onto a computer. All sound processing was performed in this format, with the final mix then being down-sampled to CD format.

This is like when people complain that FM always sounds so much better than the newfangled digital radio, without realising that the station signal was transferred to the transmission stations in digital form, often at lower bit-rate than the newfangled digital radio.

People like the nice familiar sound of low quality audio. Lots of audio equipment deliberately adulterates the sound to "make it sound better".

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

#186

Post by baq » Thu, Nov 01, 2018, 10:50 AM UTC

WalterBright wrote: post #151

mrob wrote: post #42

It's bizarre how none of these chips seem to have a digital input. All my music is digital, and despite the modern rise of vinyl, I don't think that's unusual. If I want an amplifier like this then I'm forced to have a completely useless DAC/ADC pair degrading the signal quality. Does anybody know of an easily available class-D amplifier with digital input? You'd think that would be an obvious feature for a digital a…

All stereo components, except the amp connection to the speaker, should be ethernet. Turntable, CD player, cassette, pre-amp, everything. Then make it wifi. Just think, you could eliminate that awful rat's nest of cables. The sound quality would be better. You could locate components where-ever convenient. Each component could have a web browser interface. It'd be awesome.

Sonos, d&m heos and Yamaha's multiroom iirc do half of that and yes, latency must be tightly controlled. I imagine with sources also being 802.11 it'd be much harder to keep it in reins.

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

#187

Post by rectang » Thu, Nov 01, 2018, 10:54 AM UTC

ericdykstra wrote: post #165

rectang wrote: post #134

Earlier quoted context omitted.

I made my living as a mastering engineer for two years... To do good work in mixing and mastering, it's important to study the human perceptual mechanism and its propensity for illusion, and it's also important to understand masking effects and how to amplify certain components long enough to tweak them before dialing them back to recede into the gestalt. It's also important to understand that in sound reproduction t…

This is pretty fascinating. I can't add to a discussion, but I would certainly read more about this if you have produced it somewhere. I'm also curious, what made you leave your job as a mastering engineer?

The profession of audio production is extremely competitive because there is a perpetual oversupply of labor. The total amount of money in the music industry is also deceptively small compared to its high public profile.

I left the field (back in about 2003) because although I felt that I was good enough to compete and survive, I didn't love it enough to grind out a life as a workaholic and just get by.

Most of my writings from that time were forum posts with the perspective of the well-meaning but undereducated skeptic and wouldn't be that interesting to read today. Also, what was probably my best writing happened in forums which don't have public archives which have survived 15-20 years later. (Which amuses me as a former mastering engineer because one of our primary objectives is long-term archival.)

PS: not "enharmonic", "non-harmonic" dammit. The point is that while analog distortion is mostly harmonically related, digital distortion is not and therefore is much more poisonous in small quantities. Mixing especially (though mastering is similar) is all about making changes near or below the threshold of perception which sum to a cumulative perceptible effect.

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

#188

Post by paulie_a » Thu, Nov 01, 2018, 11:00 AM UTC

AceJohnny2 wrote: post #3

scblock wrote: post #2

Oh geez they could have left this statement out: "When I wrote my previous article, class-D audio was fairly new, and audiophiles were still arguing about whether class-D amps could sound as good as class-AB or class-A units. Nobody is having those arguments anymore." Those arguments are still front and center when it comes to amplifier design, both on the manufacturer and consumer sides.

Tangentially, the placebo effect is everywhere. If it can affect tasting (wine) and hearing (audiophile gear), I'm surprised not to have noticed its affect in discussing photography. Will "computational photography" (as touted in the latest iPhones) that alters photos based on criterion of perceived quality end up bringing these kind of inane discussions there too? Edit: Never mind, I didn't factor in all the argumen…

Whenever I see the term audiophile I mentally replace it with "over priced bullshit"

It's just someone being sold snake oil.

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

#189

Post by archi42 » Thu, Nov 01, 2018, 11:02 AM UTC

mrob wrote: post #42

It's bizarre how none of these chips seem to have a digital input. All my music is digital, and despite the modern rise of vinyl, I don't think that's unusual. If I want an amplifier like this then I'm forced to have a completely useless DAC/ADC pair degrading the signal quality. Does anybody know of an easily available class-D amplifier with digital input? You'd think that would be an obvious feature for a digital a…

Don't they make these ICs with I2S? Then all you need is something that digitally interfaces with your source (eg toslink, usb) and "unpacks" the PCM data and sends it out via i2s.

Edit: look for example at TI TAS5756M, TAS3251 or TAS5825M.

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

#190

Post by imtringued » Thu, Nov 01, 2018, 11:15 AM UTC

trentlott wrote: post #136

blattimwind wrote: post #55

Earlier quoted context omitted.

I guess in technical terms this article is about "making" an amplifier as opposed to "building" an amplifier. "Making" as in "Maker", since the electronics come as pre-made assemblies connected together and put in a case.

Basically a model kit that inhibits your ability to generalize.

The first step of generalization is copying.