A/D/A converters - help me cut through the BS

[scott2000]

  Next up digital stair steps…

Lollipop "POP" bud um bum bum

 

[ruairioflaherty]

Ok, I'll try to contribute something useful.  An anecdote from maybe 10 or 11 years ago. 

I had 3 x DA converters to compare - a Benchmark DAC1, a Prism Sound DA-2  and the internal converter on a Cranesong Avocet.  I matched the output of all converters exactly and connected the Benchmark and Prism to 2 available analog inputs on the Cranesong.  The rest of the path was Hypex UCD400HXR amps and PMC MB2S speakers in a decent room.

Lots of listening later I couldn't really hear significant differences between the converters.  Next test was to bypass the Avocet analog inputs and feed each DAC through a good 5k passive attenuator, suddenly there were significant differences to be heard.  Following that I attenuated digitally and fed the converters directly to the power amps and again significant differences.

The upshot?  The distortion in Avocet analog stage was washing out the differences between the converters.  Subsequent measurements helped to confirm.  Needless to say I sold that unit.

I recently got the opportunity to listen to and measure the performance of the very latest generation Avocet, it was interesting for sure to contrast the comments on Gearslutz vs the actual performance.

 

[john12ax7]

These certain circumstances are when the internal clock is incredibly poorly designed; it's not likely to happen in real life, except if the internal clock is defective. This is clearly a case of degraded performance, which should not be the basis for generalization.
Grimm have to find an argument for selling their master clocks.

Perhaps,  but it also means the most ubiquitous converter that was in just about every major studio was / is poorly designed

I find the Grimm articles to be more science than salesmanship, especially compared to some of the other guys.  With the right internal clock / PLL an external clock won't help, they acknowledge that.

 

[scott2000]

What is interesting to me is that , at the end of the day, good music will find it's way through regardless of conversion.

I'm not sure I'm completely understanding the fact that a 10 year old Benchmark DAC, or any of the other higher end converters mentioned don't perform better than the 10 year old Motu but, if it (MOTU) does what it can and is reliable enough to keep the creativity moving forward, I'm all for it.  There are no Motu comparisons technically or subjectively mentioned so it's on to the music as it probably should be.

 

[ruairioflaherty]

On the long list of things that screw up records these days converters are down near the very bottom, no doubt.

 

[Matt C]

Why do converter and clocking threads always go off the rails so quickly?  Next up digital stair steps…

To be fair it didn't go THAT far off the rails, but yeah I don't quite get why many people have such strong feelings about converters...

I appreciate both the information/reading recommendations and the reality check

 

[living sounds]

Converters... it's complicated. On paper, modern converters should be plenty good enough. But my ears tell me otherwise. Listen to an analog source, like a hardware synth, and you'll find the converters take away the snappyness, bass impact, add a certain grain and blur etc. Clocking has something to do with it from my experimentation, and the filters implimented in the converter play a very important role, too.

Paradoxically, even DC coupled converters with a flat frequency and phase response in the low end measured with sine waves can audibly take away bass.

I'm currently using 15-20 years old converters that allow for a maximum sampling frequency of 48khz. To my ears these sound more natural and musical than more expensive, much more recent ones I've tried. Probably due to the linear phase filters implimented in more recent filters, those can really ruin a signal.

Audiodiffmaker is an interesting tool for measuring converter performance (mostly phase response). The ones that do well here tend to agree with my hearing.

It's also enlightening  to measure the phase response of converters. This can be done with the free HolmImpulse software. For instance, it reveals weird behaviour in the Lynx Aurora at 44,1 khz.

There are those who see the root of the problem in S-D-algorithms. If you want to DIY, you can get the Soekris ladder DAC, built discretely with ultra high precision resistors. You can also choose and even design your own reconstruction filters.

http://www.diyaudio.com/forums/vendor-s-bazaar/259488-reference-dac-module-discrete-2r-sign-magnitude-24-bit-384-khz.html

http://soekris.dk/dam1021.html

My ultimate goal is to build a 32-channel Soekris DAC.

He may also design an AD-converter based on the latest precision SAR chips build for medical and measuring applications...  8)

 

[abbey road d enfer]

To my ears these sound more natural and musical than more expensive, much more recent ones I've tried. Probably due to the linear phase filters implimented in more recent filters, those can really ruin a signal.

You may be onto something there; indeed, some recent research has shown audibility of pre-ringing of LP filters.

There are those who see the root of the problem in S-D-algorithms.

There is less evidence to support that.

 

[Recording Engineer]

But see, that's not a way to judge a converter. There are so many variables impedance wise The input impedance of the powered speaker and the A/D will be different. Could be a little, could be a lot. A DI Box will be sensitive to that.  AND the output of the DI is WAY different than the output of the D/A. If your doing A/B tests make sure your comparing apples to apples a half DB difference in level and that throws the whole test off.

Ok, let’s take a look.
192 Input - 12k
192 Output - 50
ADAM S3A Input - 10k
Avalon U5 Output - 600
I don’t know. Seems pretty straight-forward. I certainly wouldn’t expect some drastic change in the low end due to great impedance mismatching myself. You?

 

[living sounds]

There is less evidence to support that.

Well, there are good reasons why most quality converter chips today  provide a mix of multibit and S-D technology. S-D also puts higher demands on the surrounding circuitry, especially the clocking. To my ears DACs based on the highest quality R2R chips or ADCs based on discrete SAR implimentations sound more natural and musical than any S-D converters I have listened to so far.

Interestingly, the old converters I am currently using produce spurious tones at a low level (low enough not to be bothered by them). Maybe it's the algorithms in modern converters suppressing these S-D artifacts that actually audibly affect sound quality...

 

[Recording Engineer]

Interesting about the Avid converters,  as I've almost universally heard that the new ones were better.

While I’ve certainly not done any comparisons whatsoever or even a simple test, I do like the new Avid I/O much better than the old Digidesigns.

bluebird mentions they have significantly less hardware inside and he’s absolutely right. Except, I think it’s for the better! While never analyzed it at all, I do remember looking at my 192s thinking damn that seems like a lot of unnecessary stuff in the analog signal path! And again no analyzation at all, but a quick glance at the Avid makes me think I may have been right! Come-away with what you will as I very well may be completely off there.

 

[abbey road d enfer]

Well, there are good reasons why most quality converter chips today  provide a mix of multibit and S-D technology. S-D also puts higher demands on the surrounding circuitry, especially the clocking.

If you were referring to 1-bit Sigma-Delta, yes they put a lot of demand on everything. That's why multibit Sigma-Delta have completely replaced them, as far as I know.

To my ears DACs based on the highest quality R2R chips or ADCs based on discrete SAR implimentations sound more natural and musical than any S-D converters I have listened to so far.

It is possible, I have no experience with them. SAR puts even more demand on every part of the circuit and R2R puts more demand on your wallet; as mentioned on one of the articles, they may offer better performance because they are better built, just because they are inherently expensive.

Interestingly, the old converters I am currently using produce spurious tones at a low level (low enough not to be bothered by them). Maybe it's the algorithms in modern converters suppressing these S-D artifacts that actually audibly affect sound quality...

I don't think there's anything in the algos dedicated to the elimination of spurious. Most spurious are due to defects in the analog path of both the signal and the clock. Improvements in chip design and manufacturing are probably responsible for it.

 

[seva]

nice share living sounds

This sounds very interesting with your old converters. Which ones do you use?

I have a simple test to judge the clocking. I switch back and forth between M and LR. The side signal sounds like being washed away by a curtain with a bad clock. No need for blind testing of recorded files or measurements because you can hear it instantly.

It is logical that the best available DA converter should be attached to the monitor controller.

There is a new converter from Dangerous that I will test soon. It is the AD +. Really interesting features for mastering.
This is a nice idea for a dynamic reduction!

I think that many people know that gainstaging is a big topic in mastering. AD converters sound very different even at different levels. It is very common to feed the converter at hot levels to produce density and sound - some call it destroying it. No matter, often that sounds good. Or in other words, better than without. Expensive converters can usually do that much better than cheap ones, Its not only about loudness when I doing that.

 

[Andy Peters]

Ok, let’s take a look.
192 Input - 12k
192 Output - 50
ADAM S3A Input - 10k
Avalon U5 Output - 600
I don’t know. Seems pretty straight-forward. I certainly wouldn’t expect some drastic change in the low end due to great impedance mismatching myself. You?

I wonder if the Avalon output impedance spec isn't the device's output impedance but rather the minimum load impedance it can stand before affecting performance?

 

[mobdirt]

The convertors in the PARIS system sounded pretty good, like a hundred years ago, wonder who made those..

 

[Andy Peters]

The convertors in the PARIS system sounded pretty good, like a hundred years ago, wonder who made those..

Might've been PCM63.

 

[bluebird]

No need for blind testing of recorded files or measurements because you can hear it instantly.

And that's exactly what the career professional recording engineers and mastering engineers said, right before they got about half of they're guesses wrong when trying to pick out which converter was which. This studio had three different rooms all equipped with hundreds of thousands of dollars of recording and listening equipment. Some of the best in the world.

So I'm just really having a hard time with the descriptions of the differences you people are hearing in converter technology.
I would also like to add I am a professional mastering engineer and listen to music all day long, every day in a treated room with $40,000 worth of speakers and amps. I use Lavry Blue converters which are pretty old and make a good living doing so. The last thing I would update in my room if I had all the money in the world would be those converters and if I did, it would be purely for show.

I suggest you do proper AB/X tests with proper equipment for yourselves before you throw around such strong opinions. And if you have, please describe the test procedure and equipment you used so your findings can be taken for more than just a poetic or sudo-technical opinion.  Hell, if the your tests are technically sound, I have an open mind and would consider trying them myself. After all my tests were 5 years ago and things could have changed...

I'm really not trying to be a jerk about this but these opinions can cause people like the original poster to spend a lot of hard earned money on something that wouldn't make a mouse farts worth of difference compared to buying a nice microphone or piece of outboard gear of the same monetary value.

 

[seva]

I'm sorry that I can not provide you with measurement data. I'm not familiar with the built-in chips etc and I'm a beginner in electronics.

I like to pass on my knowledge from practice. I know only the Lavry Gold converter which sounds a bit midrange emphasized but of which there are indeed various models. I will test the blues after your statement.

It's hard not to be poetic when data is missing to describe this behavior. I hope you can close some gaps from the technical side.

Ok, if your tests are a bit dated, I recommend doing it again. I have ordered some demo converters and the clock. Just call the manufacturers or the trade.

Tests can be done easily. Sit back on the couch and switch between internal clocking and external. Do the mid side comparison on your monitor controller with both clocks.

I bet you'll notice a difference.

Better technology is not necessarily always better. Sound is very subjective and I use the behavior of converters to handle different jobs.

I'm still unsure if I feel the Solaris musically because it has extremely different transient behavior. It is definitely a good tool to make decisions. like a 4k display

Various source material at different levels changes the behavior of the AD converter. Especially if you work with high levels and analog distortion.
Maybe it was common yesterday to clip an AD but in practice it is still done today.

I do not want to unsettle anyone here. But from my point of view, you can only do it right if you invest your money in good speakers and converters. Lavry Blue also costs a bit.

 

[scott2000]

And that's exactly what the career professional recording engineers and mastering engineers said, right before they got about half of they're guesses wrong when trying to pick out which converter was which.

There wasn't a MOTU 24io?

[/quote]

This studio had three different rooms all equipped with hundreds of thousands of dollars of recording and listening equipment. Some of the best in the world.

Any MOTU 24ios?

So I'm just really having a hard time with the descriptions of the differences you people are hearing in converter technology.

Have you compared a MOTU 24io to converters you have heard?

I use Lavry Blue converters which are pretty old and make a good living doing so.

The OP mentioned a MOTU. Have you compared the Lavry to this technically or subjectively?

The last thing I would update in my room if I had all the money in the world would be those converters and if I did, it would be purely for show.

I agree. "Those" converters are incredible imo

I suggest you do proper AB/X tests with proper equipment for yourselves before you throw around such strong opinions.

Agree

I'm really not trying to be a jerk about this but these opinions can cause people like the original poster to spend a lot of hard earned money on something that wouldn't make a mouse farts worth of difference compared to buying a nice microphone or piece of outboard gear of the same monetary value.

Yes. Throwing money away on converters is a bad thing imo if we're talking mouse farts differences. I would just hate for the MOTU compared to a Lavry or the others being compared here to be more of the elephant fart in his room . He may find that a mixer would be more appealing along with a higher end 2 , 8 or 16 channel converter if he A/Bs say the MOTU with even the older Mytek 8x96 or Rosetta 16Xs?

Maybe there won't be a difference....I've never compared a MOTU 24io and there was a positive mention about one earlier so, although a subjective opinion, I'd feel ok that someone else is using one and making music. Then again, you are using a Lavry and I'd feel ok that someone was using one of those and making music as well....... Heck, if you were using a MOTU, I may go out and try one myself because I respect your information tremendously....

 

[scott2000]

There are a lot of opinions floating around out there but in my many years working in studios either recording or being a technician has anyone ever proven to me one converter "beat" another converter...
Just ask yourself how many great sounding albums were made on the old digidesign 888's. Or ADAT's remember those? Alanis Morissette Jagged Little Pill was recorded on ADAT...

Dude just get the MOTU...Concentrate on your gain staging with that console, the distortion and image problems you have are going to be a result of your ability as an engineer, not your converters.

This is great advice!!!

In my opinion it doesn't imply that  Lavry Blue conversion is going to sound like a Motu 24io but instead points out the ultimate truth at the end of the day.......