Can we agree headphone amplifiers are solved?

[Blumlein 88]

Though not small we also have things like the DBX Driverack series. Meant for PA use though useful for some home installations.
https://www.sweetwater.com/store/de...ck-pa2-complete-loudspeaker-management-system
8 band parametric EQ for 6 outputs (they have larger models). How cool is it these are even available for improving live music systems over PA's? You can control them over a phone app remotely too. Behringer has a similar couple devices for less money.

 

[KeithPhantom]

Also, I don't feel filters are SOTA yet either, aside from FPGA implementations like the sort from Chord using million taps supposedly, where you get a really nice brickwall. ESS is good enough though, but AKM I'm a bit disappointed didn't have a nice 22kHz brickwall from their latest 4499 offering (but it seems they're doing this on purpose or is a technical limit of their design as someone spoke to me about a while ago).

Why do you think filters aren't completely solved? We're talking about issues where the most differences are located during the transition band, and any possible aliasing/imaging due to malfunction is going to be minimal with the included default filters.

 

[Tks]

Why do you think filters aren't completely solved? We're talking about issues where the most differences are located during the transition band, and any possible aliasing/imaging due to malfunction is going to be minimal with the included default filters.

It's not that they're not solved, it's the available ones don't have those nice picture perfect brickwalls. You'll get some that attenuate at the proper 22.05, but then start rising right back up or such. Just another engineering circlejerk notion, not that the actual case being that filters aren't solved, I'd like to see cleaner ones, that attenuate to more than -100dB, and fast. Solved in my usage here simply means cleaner brickwalls basically, that attenuate at the proper 22.05, no sooner, no later, and go deep. In the same way desktop amps were solved a while ago, but only now we're getting something like the Schiit or Topping or Geshelli products that makes you squint wondering where the distortion or noise even is.

 

[KeithPhantom]

It's not that they're not solved, it's the available ones don't have those nice picture perfect brickwalls. You'll get some that attenuate at the proper 22.05, but then start rising right back up or such. Just another engineering circlejerk notion, not that the actual case being that filters aren't solved, I'd like to see cleaner ones, that attenuate to more than -100dB, and fast. Solved in my usage here simply means cleaner brickwalls basically, that attenuate at the proper 22.05, no sooner, no later, and go deep. In the same way desktop amps were solved a while ago, but only now we're getting something like the Schiit or Topping or Geshelli products that makes you squint wondering where the distortion or noise even is.

The same way I would like to see perfect sine waves at -120 dBFS, but sometimes we get the Bifrost that makes that sine wave into something special (you know what I mean ).

 

[Tks]

The same way I would like to see perfect sine waves at -120 dBFS, but sometimes we get the Bifrost that makes that sine wave into something special (you know what I mean ).

Cease words my man, I got what you're looking for

 

[KeithPhantom]

Cease words my man, I got what you're looking for

I guess I can make a R2R DAC using carbon-film resistors with a tolerance up to 20% on my breadboard and sell it to audiophiles, it seems like a good business idea. But seriously, those measurements are laughable.

 

[cistercian]

Yeah I was actually reading something to this effect recently, that higher dynamic range is possible by splicing different parts of the signal range to be handled by separate DACs. Just seems expensive (or just unconventional?). Not sure which, but I think this is really cool that ADC's seem to implement this regularly more than DACs themselves?

As far as ADC's being solved, I was not clear. I mean't solved in the sense of performance at costs seen from DACs for example. Also even if their performance was at such (I know RME's PRO is pretty SOTA), and even if the price was there. There just doesn't seem to be many ADC+DAC bundled devices nor mini-devices like the USB DAC sizes or inline mics as options for headphone cables and such. So solved in my machination would include availability, and various number of various offerings.

Speaking of 24-bit ADC's, it seems LG's V series (at least the V50 and later for sure that I know of) have recording capability of 44.1, 48, 88.2, 96, 192 all at either 16, or 24-bit ranges, and can be saved instantly as M4A, WAV, or FLAC. Really cool to see that.

Also, I don't feel filters are SOTA yet either, aside from FPGA implementations like the sort from Chord using million taps supposedly, where you get a really nice brickwall. ESS is good enough though, but AKM I'm a bit disappointed didn't have a nice 22kHz brickwall from their latest 4499 offering (but it seems they're doing this on purpose or is a technical limit of their design as someone spoke to me about a while ago).

Oh and DSP is definitely not solved. Even my RME DAC doesn't do low pass or high pass filtering as well as I'd expect (it's pretty lazy in terms of the slope dB/octave). Compared to JRiver for example that can muster 48dB/octave, the RME seems to be somewhere around 12db/octave or so(maybe better, but I'm not sure). Not bad, but I want more agressive sloping (though of course this could be included in your notion of creature comforts). Not sure how scaling of processing power that is required here, but surly I would imagine we'd be more far ahead at getting more DSP in more of these audiophile devices.


Also, do you think AVR's and Power Amps should be in a better place by now, or do you think their performance is gated by our best minds on the matter itself? And one final question since I highly value your opinion and have learned a lot from reading your technical exchanges with others. The transducer issue, what is the actual problem? Is it simply a material science ordeal? Inability to find a material to suit the higher performance aspiration. Or is it something else like dumb enclosure designs that eventually ruin nearly all transducer implementations? I'm really curious to know what exactly is the problem. And how far are we from what you would consider transducers to be as "solved"?

Oh and would microphones themselves be considered in your transducer defintion? I've seen some crazy vid Amir posted a little while back about some scientific microphone picking up on the chewing noises of some leaf eating worm and such. Any thoughts?

I have an old Electro-Voice horn speaker, a compound diffraction projector. it is a "full range" pa horn and I scored it for 25 dollars
in a antique shop. It works perfectly and they still make a similar horn...over 700 dollars! Yikes! I used it as a directional microphone
on a homemade portable audio amp that drove my closed back headphones. Pointing it out a window one morning the number of
different bird species I could hear was amazing. I also heard something loudly munching...but I could not see the source at first.
A caterpillar chewing a leaf about 3 feet in front of the speaker! I was amazed at how clearly I could hear it!
EV 847A CDP, it also is very efficient and when connected to a portable scanner with an anemic audio out sounds like
the police car is parked in the house! Great for discovering how much reflection and reverb affects some rooms. Directional
mics are cool.

 

[cistercian]

On topic...how about optical encoders for volume control on headphone amps? Pots are noisy and wear too.
Small step size would be nice too. My RME DAC has this and it will never get scratchy. It would be epic to
see this on lower priced gear too.

 

[Blumlein 88]

snip...

Also, do you think AVR's and Power Amps should be in a better place by now, or do you think their performance is gated by our best minds on the matter itself? And one final question since I highly value your opinion and have learned a lot from reading your technical exchanges with others. The transducer issue, what is the actual problem? Is it simply a material science ordeal? Inability to find a material to suit the higher performance aspiration. Or is it something else like dumb enclosure designs that eventually ruin nearly all transducer implementations? I'm really curious to know what exactly is the problem. And how far are we from what you would consider transducers to be as "solved"?

Oh and would microphones themselves be considered in your transducer defintion? I've seen some crazy vid Amir posted a little while back about some scientific microphone picking up on the chewing noises of some leaf eating worm and such. Any thoughts?

First off, I'm no expert on these things. Just another enthusiast and don't want someone thinking I am or that I think I'm an expert. Way more knowledgeable people are here on ASR than me.

I'll give my two cents opinion.

Power amps I think at least several are good enough it can be considered solved. One can ask for a little more or maybe at lower pricing. One still finds abysmal offerings, but that is more a marketing and profit thing. Amir is exposing those all along so hopefully they'll begin to go away as there is no reason they shouldn't be better in general.

AVR's I don't know enough to know where the problem holding them back is. Mostly lack of competition and they are so complex people quit testing them and companies just took advantage of that for raking in profit with just nearly good enough products. Obviously using a pre/pro and separate amps you can have as good an amp as you wish, but the pre/pro's just aren't that good either. Is the combination of various format standards and processing you need for RoomEQ and such preventing better basic performance? I figure it is a cost issue again.

For instance I see no reason one couldn't design a device whose sole purpose is to decode and process a Dolby Atmos signal and do nothing else at all. No other formats, nothing. I see nothing about such a device that would prevent it from reaching SOTA results to feed onto the power amp stage. I see no reason you couldn't do this individually for each of the major video formats. It might be expensive, but I'm at a loss when I see $6000 pre/pro that has the same performance as a $600 AVR to understand what the extra money has purchased in terms of performance. There are some esoteric AV devices that allegedly get you SOTA results, but the costs are $10k and up. I find it hard to believe you can't do it for less.

Speakers suffered from the circle of confusion problem. What did you want a speaker to do? We have the target now from the Harman work. While it needs some polishing it seems to me the right idea and the right direction. Speakers like the Kii Three and Dutch&Dutch look like ways you can actively control directivity to get a perfect result or close to it in regards to Harman's goals. I think you'll always have some issues as long as we need to use separate drivers for separate frequency ranges. Coaxial speakers seem to cause more trouble than they solve. And of course power handling and distortion could be improved. Mainly in the near future I think active speakers using DSP and approaches to control directivty actively will provide improvements on the speaker side. Oh, and stereo is never going to provide a real life recreation. So don't know what to do about that.

Yes, I had microphones in mind as transducers too. So you want my opinion on something I know even less about. There isn't really a circle of confusion here except by choice. I have and like to use some Shure KSM32 mics. They are impressively flat except for just a little uneveness in the low treble, but less of it than most. They have a rep for being sterile, almost always capable of good acceptable results, but not great results, lacking in mojo, and not cutting thru the mix, an okay workhorse microphone. You see people aren't looking for an accurate microphone. And that is before you do all the processing to whatever the microphone feeds into your gear. The KSM32's however can do a really nice recording of what something sounded like where you put the microphone.

And what you might want the mike to do is also effected by using it in stereo, or surround or whatever. The deficiencies of that put you inside certain envelopes of performance. You've had for some time now things like the Calrec Soundfield mics which allow you to record and choose directional patterns and aiming after the fact. But if you aren't doing purist recordings anyway that isn't of much benefit to you. And truly purist recordings aren't even at a 1 in 1000 level of anything that matters. Now the big money is working on object oriented recordings. You use processing and multiple channels to just create/record the basic raw elements and place sound objects in a synthetic world you created. So there is some that can be done to improve microphones. I'd suggest they are much better behaved in general than speakers however. Speakers are the worst transducer and THE bottleneck in audio as it stands by at least an order of magnitude.

 

[Tks]

@Blumlein 88

Really enjoyed reading that. Really good news to hear mics aren't too bad. I wanted to try dabbling in recording stuff, but I've got lots more reading to do with respect to mics (not interested in anything surround-sound beyond perhaps binaural which isn't really surround so eh).

As for power amps, the reason I'm a bit hesitant to call them solved, is due to two reasons. The first being, they're used to run the biggest bottleneck in audio (speakers), so if the source isn't good, I imagine that bleeds on over to the final sound produced. It would be okay if power amp performance was running headphones/IEMs. But already problematic speaker transducers? I feel there's lots more for power amps to improve to compensate for speakers a for a while. The second, and I think more powerful indicator, is the fact that Benchmark has ruled for over half a decade with their power amp for all we know. So simply by definition power amps have more moving to do (unless someone wants to say Benchmark literally ended the power amp competition to perpituity, and time to close up shop for anyone attempting performance competition), which I find to be silly (the notion of electronics and tech being "finished" in actuality, and especially in terms of competition).

Speaking of the AVR devil though, miracles are occurring..

 

[Inner Space]

AVR's I don't know enough to know where the problem holding them back is.

How far is our solar system from its third-closest neighboring galaxy? However many trillions of light years that is, it's a small distance compared to the gulf between normal consumers and ASR members. In other words, the problem with AVRs is my family.

Start with my daughter. She loves, loves, loves movies and TV, both in a serious analytical way, and as a helpless fan. Visual storytelling is of huge cultural importance to her. Her life would be empty without it. Yet she listens to her TV through the built-in speakers. She absolutely doesn't want anything better. Or my brother and his wife. They bought a new house, so felt they "ought" to buy a new TV, and got a Bose soundbar to go with it. Again, sophisticated, literate folks, who take movies seriously. Or my other sister-in-law, who bought an HT-in-a-box thing, and kinda got some of it hooked up, and has been happy with the result for the last eleven years. A librarian, who reads books you never heard of.

Standards will always be as low as they can go, until demand forces them up. And it isn't doing that. 99.9% of people are perfectly happy with what's on offer. Often delighted and impressed. The video side seems to dominate completely. Whereas headphones - lamely trying to stay on topic - have become a huge market, big enough to make the tiny SOTA sliver worth catering to. Somehow the HT market didn't pan out the same way. There's the anything-will-do folks (i.e. my family), and the big-explosion folks (like Beats headphone people), but the demand at the top seems weaker and narrower. Because it's much more expensive than headphones? Probably, but without the demand, AVRs will always be as bad as they can get away with.

 

[bigjacko]

I think headphone amp is still not completely solved yet. The channel crosstalk for l30 is -91dB, far from good SINAD. I would also hope that we can get IMD to be lower than -120dB. I would guess after 5 years we can finally say headphone amp is completely solved.

For speaker amp John said topping is making better SINAD amp than purifi, I am very looking forward to that and hope the price would goes down like headphone amp is now. I would guess after 7 years the speaker amp would be complete solved.

For transducers we need mechanical engineering to keep up, but seems like no company really want to do that except for purifi. Electronic is already solved for many decades, but only got better recently due to ASR. I am not very familiar with the technology in transducers, but I guess it is not solved yet, not like electronics.

 

[jae]

It's not solved until there's a product that satisfies all my criteria.

 

[Hrodulf]

I don't think that either amps nor DACs are solved. Of course, it begs the question - what are the criteria for the problem to be solved. The current suite of electronic tests can be reliably passed by relatively affordable amps and DACs. However, the problem lies in the fact that the current suite of standard electronic tests are poor predictors for listener preference. In other words - there is no spinorama for electronics. Again - can there be a spinorama for electronics? Do people have a common and constant preference across cultures, degrees of expertise and types of music for electronics? If yes, then the current set of standard electronic measurements lacks sophistication. It's like measuring only on-axis AFR for a loudspeaker and calling it a day.

 

[Pluto]

That's where I'd like to see research and development going, a way of reproducing a complete soundfield

I thought Ambisonics had largely cracked that, in principal. Still, as long as we proceed along open source lines.

Not something based on the world envisioned by the Dolby corporation…

 

[Blumlein 88]

I don't think that either amps nor DACs are solved. Of course, it begs the question - what are the criteria for the problem to be solved. The current suite of electronic tests can be reliably passed by relatively affordable amps and DACs. However, the problem lies in the fact that the current suite of standard electronic tests are poor predictors for listener preference. In other words - there is no spinorama for electronics. Again - can there be a spinorama for electronics? Do people have a common and constant preference across cultures, degrees of expertise and types of music for electronics? If yes, then the current set of standard electronic measurements lacks sophistication. It's like measuring only on-axis AFR for a loudspeaker and calling it a day.

Fidelity to the Signal is the criteria.

Such devices are capable of transparency. Meaning no preference is possible. They exceed the limits of human perception.

 

[Fluffy]

I don't think that either amps nor DACs are solved. Of course, it begs the question - what are the criteria for the problem to be solved. The current suite of electronic tests can be reliably passed by relatively affordable amps and DACs. However, the problem lies in the fact that the current suite of standard electronic tests are poor predictors for listener preference. In other words - there is no spinorama for electronics. Again - can there be a spinorama for electronics? Do people have a common and constant preference across cultures, degrees of expertise and types of music for electronics? If yes, then the current set of standard electronic measurements lacks sophistication. It's like measuring only on-axis AFR for a loudspeaker and calling it a day.

This argument is based on the archaic ideal that electronics should play a part in how things "sound". it's a remnant from times where it wasn't yet possible engineering an amplifier or converter without substantial signal degradation. So the marketing spin was that this degradation is "euphonic" or "warm" or "desirable", and compromising on one form of degradation over another was called "voicing".

But if we put aside that confused part of history, the simple fact is that the job of an amplifier is simply to amplify voltage, nothing more. If it does its job correctly and without signal degradation, it doesn't and shouldn't have any contribution to the sound. Ideally, the only part of the system that should affect the resulting sound (acoustic waves in the air) is the part that actually produces sound waves, and that is the transducer.

Dacs and headphone amps are basically at a point that they contribute so little degradation to the signal that they can be considered perfectly transparent conduits of signal, just like cables (relative to the perceptual limits of the human brain).

 

[Blumlein 88]

I thought Ambisonics had largely cracked that, in principal. Still, as long as we proceed along open source lines.

Not something based on the world envisioned by the Dolby corporation…

No ambisonics doesn't quite do it.

Maybe JJ's soundfield reconstruction.

 

[bobbooo]

Fidelity to the Signal is the criteria.

Such devices are capable of transparency. Meaning no preference is possible. They exceed the limits of human perception.

The question is, what signal? They may be transparent and exceed the limits of perception when playing sine tones, but what about the thing we actually use them to play and listen to, music? Is there any evidence of a monotonic correlation between DAC/amps' fidelity/degradation of a sine signal and their fidelity/degradation of a music signal? There is in fact some suggestive evidence any such correlation is actually poor, which could mean a device that is audibly transparent when playing sine tones may not be transparent when playing music.

(By the way, I'd argue the exact same criteria applies to transducers - fidelity to the source. Except in this case the 'source' is the sound the engineer heard from their studio monitors when mastering the music you're listening to.)

 

[sergeauckland]

I thought Ambisonics had largely cracked that, in principal. Still, as long as we proceed along open source lines.

Not something based on the world envisioned by the Dolby corporation…

Exactly. However, as you said, Ambisonics cracked the principles, but under NRDC was never allowed to develop it into something marketable.

Some years ago (something like 16, before I retired) the Fraunhofer Institute and Lawo in Germany did some interesting work on soundfield synthesis, but using some 400 channels of DSP, and hundreds of small loudspeakers all round a room. The idea was that at VLF, multiple loudspeakers could work together to shift enough air, whilst higher up the spectrum, individual loudspeakers would be driven individually from their own DSP channel.

I heard a demonstration at one of the European AES shows, in which they had a darkened room with a scaled-down version (only 100 or so loudspeakers) playing city traffic and other ambient noises. It was a pretty realistic demo, although walking round the room didn't give the same sonic picture as being out on the street, but for a reasonably static listener, it worked quite well.

However, even the cut-down version demoed involved 100 small two-way loudspeakers and a couple of hundred channels of DSP so hardly consumer-friendly quite apart from the cost which was something well in excess of €250,000, more like €500,000 as I recall.

Getting back to Ambisonics, as proposed, it too relied on the creation of phantom images, just in 3-D with height as well as surround. For it to work in a tetrahedral arrangement, the room would have to be huge, or limited to one listener, even more restricted than stereo. In those days there was no DSP, and I don't know what could have been the distribution medium, as it needed at least the four channels transmitting.

I'd love to see research going into this more, but I suspect that telling the public at large to install even more loudspeakers when singing brick bluetooth 'speakers seem to be the way the market is going if it's not headphones, might just be too late.

S.