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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

#221

Post by ballooney »

AnthonBerg wrote: post #210
ballooney wrote: post #172

Earlier quoted context omitted.

That’s precisely and exactly the opposite of what ‘linear’ means when talking about the operating point of transistors. I think you should rephrase your argument.

I'm going with an understanding similar to what is presented e.g. here: https://www.mwrf.com/components/learn-meaning-amplifier-line... "The term linearity derives from an amplifier's linear relationship of input power to output power which, in an ideal amplifier, would be precisely related by the gain of the amplifier." I see it as matching my argument. Could I ask you to give a definition which clashes? Thanks!

Yes, the definition of linearity is that f(A) + f(B) = f(A+B), which you have contradicted in your GP post. If a transistor is fully on, then doubling the input voltage to it will not double the output, because it's already at maximum. That is very precisely not a linear device. That's why linear amplifiers, like Class A, operate the transistor in a partially switched state, where increasing the input signal (about some bias point, and with feedback to turn a real transistor into a more ideally-behaving one) gives a corresponding increase in output signal.

Class D (switching) amplifiers are _not_ linear, they trade linearity for efficiency. The article you linked to actually says this:

"Over the years, a number of different biasing schemes have been developed for amplifiers, from extremely linear Class A operation, in which the active devices essentially remain powered on through the full sinewave cycle of an input signal, to more power-efficient schemes, such as Class D, in which multiple transistors are switched on and off to conduct different portions of an input waveform."

I think what you are doing is confusing the linearity of the transistor with the linearity of the whole audio amplifier treated as a black box, which is why I suggested you rephrase your argument rather than say you are categorically wrong, however what you said was:

"The thing is that transistors’ behavior is more linear and controlled when fully on or off rather than when used as continuously variable."

... which I'm afraid is really just wrong.

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

#222

Post by Balgair »

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…

> 2750 watt tube amps

WOW! That's ~5% of a Ducati. That's ... insane for a sound system.

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

#223

Post by jollyrogerbass »

neya wrote: post #176

After I started building my own audio gear, I am no longer impressed by what you can buy in the consumer market, no longer how much "audiophile" these systems claim to be. Usually, it's just a simple 2-way boombox sold for $xxx - $xxxx. I started my project after being disappointed with the sound quality of the Apple Homepod. So, I built my own version with inbuilt basic voice command integration. And I couldn't be h…

That looks awesome, post the guide please!

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

#224

Post by linsomniac »

I kind of want to build one of these amps and connect it to a set of speaker built with these cheap exciters... One of the Youtube channels I follow messed around with them https://youtu.be/zMCyF400l1c but he got that from this other video https://youtu.be/zdkyGDqU7xA where he goes into all sorts of experiments he ran on the exciters to find the right design.

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

#226

Post by cardinalfang »

Balgair wrote: post #222
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…

> 2750 watt tube amps WOW! That's ~5% of a Ducati. That's ... insane for a sound system.

A Ducati is a sound system.

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

#227

Post by ken »

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…

It's already here, for displays. I've seen lots of internet comments claiming I need the >450ppi screen on the new high-end iPhone, not the miserable old cheapo 326ppi one.

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

#228

Post by Tsiklon »

beat wrote: post #215
Tsiklon wrote: post #194

Earlier quoted context omitted.

I like to look on high end headphones as I would any other luxury item - I'm willing to pay for nice materials of a higher quality or a better experience, if the item is right. That could perhaps explain some of the price - plus I think we're at the point where many of the headphone companies have discovered that there is an ultra-high end market for some of these products. You can see this in the prices of many top…

Some people understand the law of diminishing returns, but have the resources to not care. If a $2000 pair of headphones is no more real financial pain for you than a $200 pair, and they're better despite diminishing returns, then why not get them?

Very correct, that's a perfectly reasonable explanation, especially in terms of the usual consumers of high end luxury goods.

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

#229

Post by compiler-guy »

blattimwind wrote: post #55
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 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.

"If you wish to make an apple pie from scratch, you must first create the universe." --Carl Sagan

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

#230

Post by rectang »

beat wrote: post #217
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…

I feel your pain. I produce and mix records - at an amateur level, but enough to get quite good at it. It makes me want to toss all this "objective", "measurable" bullshit from the skeptics right out the window - the subjective experience is all that matters. But it also makes me want to toss the audiophile voodoo out the same window. "Accurate" reproduction? I just want to show them how records are mixed. My pet exa…

I agree that your high-pass filters are an application of masking principles. It would be challenging, especially for an untrained person but even for someone who is trained, to perceive enabling/disabling of those filters in the context of the full mix. Instead we solo to isolate the track being adjusted so the change is easily audible -- i.e. no longer masked by the other tracks -- and adjust the filtering anticipating the counter-intuitive but artistically desirable effect when the filtered track is blended back into the mix.

Despite that, your hostility to the skeptics illustrates that you and I still aren't really on the same page (though I don't doubt you produce compelling art, don't question your techniques, and agree 100% about ensuring that aesthetic gestures survive the transition to imperfect end-user environments).

To me, "objective accuracy" is a worthy and desirable intermediate goal for sound artists, a tool which can be leveraged for creative ends the same as a baker understanding food chemistry or an animator understanding Newtonian physics or a modern origami folder understanding programming. However, chasing "objective accuracy" means understanding the wildly non-linear, even bizarre human perceptual mechanism -- which is more of a pattern recognition machine and definitely not a measurement device -- in addition to all the strangeness of acoustics.

The problem with audiophiles is that their approach to "accuracy" is unscientific and doomed from the start. The skeptics on the other hand, have the right idea -- but those who have not done deep study often fail to appreciate just how difficult the problem is and how far off their intuitions are.

I've had some wonderful conversations with individuals whose perspectives are similar to mine, but it still seems impossible to find a hospitable public forum.

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