Can we agree headphone amplifiers are solved?

[March Audio]

What are you basing this on? Amir doesn't really measure professional ADC devices. In ASR all I've seen are cheap interfaces. In the professional market you have digital recorders with far better quality.

Just curious, specifically what digital recorders are you referring to?

 

[sergeauckland]

Name one that's cheaper than adi2pro but better performance?

I do (did, before lockdown) a fair few recordings, and I want to use the same interface for measurements, so the issue of ADC quality is close to my heart.

One can buy a very good DAC for very little money, but a similarly good ADC, like the adi2pro, runs to well over £1000. I suppose the price difference is in part due to volumes, there are far more DACs sold than ADCs, but nevertheless, many of the inexpensive interfaces when used on loopback are just not that good when levels get anywhere near 0dBFS.

I wonder why inexpensive interfaces like the Behringers or Lexicons have such relatively poor ADC sections. If they can make a good DAC, why not ADC?

S.

 

[JohnYang1997]

I do (did, before lockdown) a fair few recordings, and I want to use the same interface for measurements, so the issue of ADC quality is close to my heart.

One can buy a very good DAC for very little money, but a similarly good ADC, like the adi2pro, runs to well over £1000. I suppose the price difference is in part due to volumes, there are far more DACs sold than ADCs, but nevertheless, many of the inexpensive interfaces when used on loopback are just not that good when levels get anywhere near 0dBFS.

I wonder why inexpensive interfaces like the Behringers or Lexicons have such relatively poor ADC sections. If they can make a good DAC, why not ADC?

S.

I'm not sure why either. But recording industry is not less fond of snake-oils than audiophiles do. I know in many times it's for creating some sound. But majority of the time people just listen with their eyes than their ears. In some ways, the recording environment needs much higher quality products than in the playback while the reality is that the preferred equipments are old with much less care about sound quality. In the early days the designers were definitely not to design with such colored sound in mind. Many techniques are invented after the equipments are sold. On the other hand, the performance of ADDA don't contribute much to the results. The techniques and the ears are way more important. The two aspects are probably what caused the current state of pro scene. Do we need such high performance? Or is it because we like it to be. Yeah, I like it to be but probably it's already good enough.

 

[MSTARK]

The way forward to this is to build a better miniDSP ears and calibrate the headphone(s) one owns through this device which then applies EQ.
This basically is what the miniDSP was designed to do. The idea is good, the implementation can be improved. I reckon it needs be affordable.
Using a large database won't cover all headphones and would need to be updated with new models coming out.
So measuring is the only logical way.

Caveats: Positioning headphones on the test rig can give substantially incorrect compensation. You could average multiple test runs. Then again it is no guarantee you will get 'perfect sound' but most likely it will be closer than doing nothing.

Totally forgot about miniDSP as an option, however. I would love to see something of that caliber and computing power implemented into a DAC. Maybe something like this already exist but I’m not aware of it?
It should not be that hard to add several preset EQ settings with ability to change values, is it?

 

[Fluffy]

Just curious, specifically what digital recorders are you referring to?

Name one that's cheaper than adi2pro but better performance?

You need to understand that the audiophile market and the professional recording market are totally separate from each other. ADCs are obviously much more important to recording than they are to audio enthusiasts, and there are completely separate brands that deal exclusively with recording devices for the professional market. From my experience as a location recordist I can name the top brands in that field which are Sound Devices, Zaxcom, and Zoom – none of their products were measured by Amir. Some products aimed at studios were measured here (RME, Focusrite, Behringer), but the prime focus here are on affordable devices for hobbyists and not the top range of audio recording capability. Generally, you can't assume anything about the state of audio recording technology by the miniscule amount of measurements that were done on ASR.

Mind you, for professional products cheapness is not really a factor. Performance and features are much more important. So the market forces would naturally tend towards high quality ADCs at higher prices, rather than lower ones. This is not dissimilar from the pricing of studio monitors – you won't fine top tier performance at consumer friendly prices.

 

[solderdude]

It should not be that hard to add several preset EQ settings with ability to change values, is it?

RME ADI2 already has this (parametric EQ with some presets) the issue is what measurements to use and how to 'automatically upload' profiles.
One would still have to manually tell the device which headphone is used.

 

[MSTARK]

RME ADI2 already has this (parametric EQ with some presets) the issue is what measurements to use and how to 'automatically upload' profiles.
One would still have to manually tell the device which headphone is used.

Heard of it but I’m not familiar with its functionality other then it could be a bit overwhelming. And, it’s still a bit pricey for most hobbies. But yeah, something like that with easier interface and profiles that could be added or removed would be nice. Of cause at more affordable price.
And naturally, those profiles could/should be tailored to taste if desired.
I know that it might be a wishful thinking but product like that with possible streaming abilities would be my go to option if it existed.
Also on that list would be an amp that can match any headphone impedance from 10-600+ ohms.
Even more ridiculous request would be an amp with selectable SS/Tube input/buffer stage. .

 

[JohnYang1997]

You need to understand that the audiophile market and the professional recording market are totally separate from each other. ADCs are obviously much more important to recording than they are to audio enthusiasts, and there are completely separate brands that deal exclusively with recording devices for the professional market. From my experience as a location recordist I can name the top brands in that field which are Sound Devices, Zaxcom, and Zoom – none of their products were measured by Amir. Some products aimed at studios were measured here (RME, Focusrite, Behringer), but the prime focus here are on affordable devices for hobbyists and not the top range of audio recording capability. Generally, you can't assume anything about the state of audio recording technology by the miniscule amount of measurements that were done on ASR.

Mind you, for professional products cheapness is not really a factor. Performance and features are much more important. So the market forces would naturally tend towards high quality ADCs at higher prices, rather than lower ones. This is not dissimilar from the pricing of studio monitors – you won't fine top tier performance at consumer friendly prices.

Apollo, prism, Apogee, and a few others were really good. But the prices are just getting more and more expensive. The revolution of good performance products were to start but didn't really start. Also we should know that home recording is just getting more and more popular. Or why do we have focusrite Scarlett. But for years the performance of scarlett didn't really change. There must be way to breakthrough.

 

[March Audio]

You need to understand that the audiophile market and the professional recording market are totally separate from each other. ADCs are obviously much more important to recording than they are to audio enthusiasts, and there are completely separate brands that deal exclusively with recording devices for the professional market. From my experience as a location recordist I can name the top brands in that field which are Sound Devices, Zaxcom, and Zoom – none of their products were measured by Amir. Some products aimed at studios were measured here (RME, Focusrite, Behringer), but the prime focus here are on affordable devices for hobbyists and not the top range of audio recording capability. Generally, you can't assume anything about the state of audio recording technology by the miniscule amount of measurements that were done on ASR.

Mind you, for professional products cheapness is not really a factor. Performance and features are much more important. So the market forces would naturally tend towards high quality ADCs at higher prices, rather than lower ones. This is not dissimilar from the pricing of studio monitors – you won't fine top tier performance at consumer friendly prices.

I think you can probably guess the point I'm alluding to.

Can we see some info on the performance of these "top professional" brands?

There are a finite number of ADC chips out there, this of course doesn't exclude the possibility of novel implementations or some kind of discrete design that offers a different level of performance, but it would be interesting to see what they are and how well they do perform.

Sound devices 888.
THD + Noise

• 0.005% Max (86dB)

Zaxcom deva 24
Thd + n 0.0015% (97dB)

Zoom uac8
DYNAMIC RANGE:AD: 120 dB typical (IHF-A) DA: 120 dB typical (IHF-A)

Decidedly mediocre.

 

[Fluffy]

I think you can probably guess the point I'm alluding to.

Can we see some info on the performance of these "top professional" brands?

There are a finite number of ADC chips out there, this of course doesn't exclude the possibility of novel implementations or some kind of discrete design that offers a different level of performance, but it would be interesting to see what they are and how well they do perform.

Sound devices 888.
THD + Noise

• 0.005% max

It would indeed be interesting to measure these – unfortunately, I didn't see such measurements. If you are hinting at the possibility that those brands sell pricy products with bad objective performance in the same way that luxury audiophile brands do – well, could be, who knows? Until someone takes a crack at measuring all of those the same way audiophile produces are measured, I guess we won't know for sure. At any rate, assuming bad or good performance without concrete evidence is moot – and that is exactly my point in response to @JohnYang1997 claim that "ADC is not yet started".

 

[March Audio]

It would indeed be interesting to measure these – unfortunately, I didn't see such measurements. If you are hinting at the possibility that those brands sell pricy products with bad objective performance in the same way that luxury audiophile brands do – well, could be, who knows? Until someone takes a crack at measuring all of those the same way audiophile produces are measured, I guess we won't know for sure. At any rate, assuming bad or good performance without concrete evidence is moot – and that is exactly my point in response to @JohnYang1997 claim that "ADC is not yet started".

Price isn't really the question. Professional kit may well have different design criteria, build quality, reliability etc. However in terms of technical performance the vast majority will be using the same ADC chips as the semi professional gear.

I just looked at some of the names you mentioned above and none of them are doing anything exceptional. For comparison:

Motu 8A.
Thd+n 0.0003% (110dB)

Rme Adi2 pro fs
Thd +n 0.00025% (112dB)

I tend to agree with @JohnYang1997 on this one.

 

[Fluffy]

Price isn't really the question. Professional kit may well have different design criteria build quality etc. However in terms of technical performance the vast majority will be using the same ADC chips as the semi professional gear.

I just looked at some of the names you mentioned and none of them are doing anything exceptional.

I tend to agree with @JohnYang1997 on this one.

I don't really get why you insist on assuming things about this companies without seeing a single reliable measurement of their gear.

As for chips, it's long established that the chip performance is much less important than implementation.

 

[March Audio]

I don't really get why you insist on assuming things about this companies without seeing a single reliable measurement of their gear.

As for chips, it's long established that the chip performance is much less important than implementation.

The numbers are from the manufacturers own data sheets. Are you suggesting that they perform far better than their own marketing indicates?

That seems unlikely doesn't it.

The good "semi pro" is already maxing out the performance of the available ADC chips.

 

[Fluffy]

The numbers are from the manufacturers data, sheets. Are you suggesting that they perform far better than their own marketing?

Is there a point to independent measuring if we 100% believe everything that marketing tells us?

 

[March Audio]

Is there a point to independent measuring if we 100% believe everything that marketing tells us?

If they were over stating their performance you would have a point, but in the examples above what they are stating is already behind the good semi pro

 

[solderdude]

Even more ridiculous request would be an amp with selectable SS/Tube input/buffer stage.

I actually helped in developping a headphone amp with selectable input stages. One could even choose between 2 different tubes, FET and 'normal' input.
This part is why they contacted me.
It also had 2 different output resistances and a few gains, digital volume control, tone control (bass treble only) and even had a class D amp.
Upgradable with DAC or other inputs (BT, phono or extra line-in).
Unfortunately the company I was helping couldn't get the firmware working and had issues with groundplane garbage and the PCB designer they used thst eventually gave up. too bad they could not make it work.

What you want basically already exists in software (the correction part) and one can choose any DAC and any amp they so desire.
It would be VERY expensive to combine this in hardware and there probably would not be much takers.
Firmware would have to be updateable and headphone profiles (made by who and in what way) as well.

 

[Fluffy]

If they were over stating their performance you would have a point, but in the examples above what they are stating is already behind the good semi pro

Not understanding the spec you are referencing to is not a good basis for assumptions. Here is one for the Sound Devices 888 analog input:

THD + Noise: 0.005% max (mic in, 1 kHz, 22 Hz–22 kHz BW, trim at 20, fader at 0, -10 dBu in)

I quoted the full thing, not just the percentage number. This is referencing the mic input receiving signal at -10 dbu, that equals to 0.2V RMS, with the analog gain (trim) set to 20 db out of a possible 76 db range.

And you're comparing that with, for example, this spec of the ADI-2 Pro FS analog input:

THD+N @ -1 dBFS: -112 dB, 0.00025 %

Again, full quote. That doesn't give almost any of the information that the first spec provided, and can't be compared directly. How do you translate the -1 DBFS here to the -10 DBU above?

Another comparison can also be made between the claimed noise performance of these devices:

ADI-2 Pro FS - Signal to Noise ratio (SNR) @ +4 dBu: 119 dB RMS unweighted, 123 dBA

Sound Devices 888 - Equivalent Input Noise -131 dBV (-129 dBu) max (mic in, A-weighting, 76 dB gain, 150 ohm source impedance)

If we just take the raw number, 129 db sounds more than 123. But does it make for a fair comparison?

Anyway, the point is that looking at spec sheets tells us close to nothing. That's why independent and consistent measuring is important for deep understanding of these products performance. Any large scale assumptions about the state of the industry ("ADCs are far from solved") should rely on solid verified data and not biased speculations. My assessment that headphones amplifiers are a solved issue comes from the many affordable SOTA amplifiers measured on ASR in the last few months – not from reading any of their spec sheets.

ASR does not come close to contain enough information on the state of ADCs at large to deduce any kind of insight.

 

[Blumlein 88]

Not understanding the spec you are referencing to is not a good basis for assumptions. Here is one for the Sound Devices 888 analog input:

THD + Noise: 0.005% max (mic in, 1 kHz, 22 Hz–22 kHz BW, trim at 20, fader at 0, -10 dBu in)

I quoted the full thing, not just the percentage number. This is referencing the mic input receiving signal at -10 dbu, that equals to 0.2V RMS, with the analog gain (trim) set to 20 db out of a possible 76 db range.

And you're comparing that with, for example, this spec of the ADI-2 Pro FS analog input:

THD+N @ -1 dBFS: -112 dB, 0.00025 %

Again, full quote. That doesn't give almost any of the information that the first spec provided, and can't be compared directly. How do you translate the -1 DBFS here to the -10 DBU above?

Another comparison can also be made between the claimed noise performance of these devices:

ADI-2 Pro FS - Signal to Noise ratio (SNR) @ +4 dBu: 119 dB RMS unweighted, 123 dBA

Sound Devices 888 - Equivalent Input Noise -131 dBV (-129 dBu) max (mic in, A-weighting, 76 dB gain, 150 ohm source impedance)

If we just take the raw number, 129 db sounds more than 123. But does it make for a fair comparison?

Anyway, the point is that looking at spec sheets tells us close to nothing. That's why independent and consistent measuring is important for deep understanding of these products performance. Any large scale assumptions about the state of the industry ("ADCs are far from solved") should rely on solid verified data and not biased speculations. My assessment that headphones amplifiers are a solved issue comes from the many affordable SOTA amplifiers measured on ASR in the last few months – not from reading any of their spec sheets.

ASR does not come close to contain enough information on the state of ADCs at large to deduce any kind of insight.

ADC makers seem to play the biggest games with dynamic range. Also we know the -10 dbu with gain set to 20 db will get worse as signal level rises and if you use additional gain the noise floor will go up. They cherry picked a sweet spot for those specs.

Generally you aren't going to find ADC's with claims of better than -100 to -110 SINAD, or SNR of better than 110 db or dynamic range if properly tested of more than 115 to 120 db. Many of your most revered and expensive models won't even list actual specs. That in itself tells you something. They don't want to explain why the basic specs of the really expensive stuff is about the same as a good semi-pro device.

Oddly in the pro recording community a near consensus has been that ADCs are a solved problem for awhile now. Seems once you get most of your THD and noise specs to around -100 db they don't perceive any benefit. Other devices raise or lower signals as needed for them and if they have a 100 db wide window to work in they seem to think nothing more is needed. Now there are plenty who go for esoteric gear and don't agree with what I wrote, but a solid portion of those making their living in that field would agree with these statements. It seems to be the difference between an audiophile wanting everything below -120 db so there can never be the theoretical possibility of something being audible, and people who make their living deciding ,"if you need more than spurious signals lower than -100 db I've never heard it or run into it." Many audiophiles are chasing these numbers assuming they'll be better even though they've heard nothing wrong with what they've got. Of course pro recording people are just trying to make some cool music. They managed that when it was within the restricted confines of reel to reel tape going onto LP.

I've put up 8th generation DAC/ADC loopback copies of music. There isn't much audible degradation there, and I was using interfaces maybe a couple steps up from the lowest of them. Neither the ADC nor DAC had SOTA specs. I would have nothing against better ADCs, but I don't know if they'll gain us a whole lot audibly if anything. I think what Zoom and Sound Devices are doing with 32 bit float recording so you can never clip and never have a noise floor problem are actually more useful.

 

[MSTARK]

I actually helped in developping a headphone amp with selectable input stages. One could even choose between 2 different tubes, FET and 'normal' input.
This part is why they contacted me.
It also had 2 different output resistances and a few gains, digital volume control, tone control (bass treble only) and even had a class D amp.
Upgradable with DAC or other inputs (BT, phono or extra line-in).
Unfortunately the company I was helping couldn't get the firmware working and had issues with groundplane garbage and the PCB designer they used thst eventually gave up. too bad they could not make it work.

What you want basically already exists in software (the correction part) and one can choose any DAC and any amp they so desire.
It would be VERY expensive to combine this in hardware and there probably would not be much takers.
Firmware would have to be updateable and headphone profiles (made by who and in what way) as well.

Too bad that amp never materialized.
A little “Swiss Army” knife that surely would make some headphone aficionados extremely happy. Even at higher price point.

As to software/PC as an answer to DSP/streaming option/correction solution ..... It sure is where those applications are thriving, especially among younger customer base. But it would be nice to have a one box solution designed with audiophiles in mind and with easy, straightforward interface. Yes, I do realize that cost of such a product might make manufacturers of “budget” components question possible return on their investment.
I know of at least one or two manufacturers that integrate streamers with their headphone amplifiers (no EQ/DSP correction tho) but those are quite pricey in respect to what it offers. Maybe Raspberry Pi based product could be an answer to keep cost down IDK????

 

[March Audio]

Not understanding the spec you are referencing to is not a good basis for assumptions. Here is one for the Sound Devices 888 analog input:

THD + Noise: 0.005% max (mic in, 1 kHz, 22 Hz–22 kHz BW, trim at 20, fader at 0, -10 dBu in)

I quoted the full thing, not just the percentage number. This is referencing the mic input receiving signal at -10 dbu, that equals to 0.2V RMS, with the analog gain (trim) set to 20 db out of a possible 76 db range.

And you're comparing that with, for example, this spec of the ADI-2 Pro FS analog input:

THD+N @ -1 dBFS: -112 dB, 0.00025 %

Again, full quote. That doesn't give almost any of the information that the first spec provided, and can't be compared directly. How do you translate the -1 DBFS here to the -10 DBU above?

Another comparison can also be made between the claimed noise performance of these devices:

ADI-2 Pro FS - Signal to Noise ratio (SNR) @ +4 dBu: 119 dB RMS unweighted, 123 dBA

Sound Devices 888 - Equivalent Input Noise -131 dBV (-129 dBu) max (mic in, A-weighting, 76 dB gain, 150 ohm source impedance)

If we just take the raw number, 129 db sounds more than 123. But does it make for a fair comparison?

Anyway, the point is that looking at spec sheets tells us close to nothing. That's why independent and consistent measuring is important for deep understanding of these products performance. Any large scale assumptions about the state of the industry ("ADCs are far from solved") should rely on solid verified data and not biased speculations. My assessment that headphones amplifiers are a solved issue comes from the many affordable SOTA amplifiers measured on ASR in the last few months – not from reading any of their spec sheets.

ASR does not come close to contain enough information on the state of ADCs at large to deduce any kind of insight.

I fully understand the spec thank you. That is all the info they published, but to take your point I can assure you they are publishing info that shows the product in its best light

You are ignoring the simple fact that the "professional" manufacturers you mention do not have access to any different or superior ADC chips over the semi professional manufacturers. The good semi professional products have maxed out the performance of these devices. There is nowhere for the "professionals" to go.

Knowledge goes beyond what's published in ASR. Just take a walk through the Texas Instruments, Analog Devices, AKM, ESS, Maxim etc ADC parts catalogues. They are full of very detailed spec sheets.