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Where have all the ADC's gone - Phono biased especially


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Have been working through an issue that has come up in a number of threads recently - analogue to digital converters for integrating vinyl into digitally based, mid level systems.   And I am thinking integration for day-to-day playing of vinyl, not just for connection to computer for digitising.  Mid level for me is solid Phono preamp around Rega Fono MM/MC level. 

From what I can tell the landscape looks something like:

  • The $50 to $80 48kHz/96kHz consumer electronics store style - I bought one for testing and not impressed
  • The Rega Phono mini A2D, and its NAD (and Pro-Ject I think) counterparts - competent in entry level systems
  • Schiit Jil (discontinued) - competent at mid level but limited to USB out.  It is expecting a PC on the other end for recording and won't drive a USB to TOSLINK/SPDIF converter for easy integration into a digital pre-amp.
  • Alpha Design Labs GT40 alpha Phono stage and ADC (around $850) - phono stage got some poor reviews but ADC seems solid
  • PA Audio NuWave Phono (discontinued) - highly regarded but scarce in second hand market.  Replaced by Stellar Phono that does not have ADC
  • Mytek Brooklyn ADC (I think still available) - but now we are up into the $3k plus arena of top end IMHO
  • The Uwe Beis kit ADC that @andyr uses - also a competent solution if you have the skills and appetite to build. 

So a narrow field.  I also have no real idea, other than 'quality reflected in price', of how to judge the quality of ADC once you get into the 24bit 192kHz etal resolution outputs.

Thoughts?

 

Gibbo

 

Edited by gibbo9000
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Start looking at pro audio brands like RME or Motu if you want decent but inexpensive ADCs.

 

the RME ADI 2 Pro would be my go to if I didn’t already have multiple FireWire interfaces (Presonus StudioLive digital mixer, Motu Ultralite) laying around

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Last time I needed one, I was very happy with the Apogee Rosetta AD. A very classic AD solution that's probably in the mastering chain for at least one album you own. Antelope used to make some nice-looking units for that cosmetic factor. I tend to assume that anything integrating the phono stage and the A/D stage is probably a compromise solution and you'll get a better result keeping them apart.

 

I used to keep the turntable quite a way away from the rest of the system because of sketchy floors in an apartment. Rather than running ten metres of noise-gathering RCA leads, I went with the turntable and phono stage connected to the Rosetta AD and ran ten metres of AES/EBU to the DAC. No mess, no fuss, no noise. 

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I have to admit that I will never understand an urge to digitise turntable analogue output. I can understand the convenience of a digital setup - but vinyl was never about convenience. What is the point introducing jitter into an already imperfect analogue signal and on top of that limiting its frequency bandwidth to ~20KHz. What is next - recording FM radio on a cassette tape and than digitising that into 24bit PCM stream?

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Because there's music that you have that was only released on vinyl and you'd like to keep a copy that won't degrade? Chances are they were mastered to a digital medium anyway. The number of records that were cut from a DAT ...

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44 minutes ago, Decky said:

I can understand the convenience of a digital setup - but vinyl was never about convenience

Sentiment understood 🙂.  A trade-off for some like me though.  Minor compromise to analogue signal vs major benefit of Dirac room correction and Cardiod sound distribution from DSP based speakers.  May not be true to pure analogue, but vinyl played through solid digital chain still maintains many of its innate characteristics and is a significant step up from streamed versions on quality albums.

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Don't forget the Parks Audio Puffin, phono stage completely in digital with a myriad of equalisation curves and the option of pure digital out if you want to use a separate DAC/DAC integrated amp.  http://parksaudiollc.com/ The quality of this is decidedly above mid-fi.

If you want to capture the digital permanently, you can attach it to an SPDIF to USB converter and record it on your PC. The most affordable option is from miniDSP. https://www.minidsp.com/products/usb-audio-interface/usbstreamer-box

So $639USD + $105USD. For a bit over a grand AUD you get an extremely high quality phono stage, multiple equalisation curves, surface noise silencer, digital out, and capture to PC.

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12 minutes ago, Ittaku said:

If you want to capture the digital permanently, you can attach it to an SPDIF to USB converter and record it on your PC.

... or some computers just have their own SPDIF connector (or header on the motherboard).... getting less common tho.

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1 hour ago, Decky said:

I have to admit that I will never understand an urge to digitise turntable analogue output. I can understand the convenience of a digital setup - but vinyl was never about convenience. What is the point introducing jitter into an already imperfect analogue signal and on top of that limiting its frequency bandwidth to ~20KHz. What is next - recording FM radio on a cassette tape and than digitising that into 24bit PCM stream?

 

It seems you are urgently in need of some LSD, Decky ... to expand your horizons !  xD

 

Firstly, the 'imperfect analogue signal ' doesn't stop at 20kHz - the way a CD does.  Have a look at some cart specs - a top end range specced to 50kHz is not uncommon.

 

Secondly, if you run active speakers then you are probably into a digital XO/room EQ environment.

 

Andy

 

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55 minutes ago, andyr said:

 

It seems you are urgently in need of some LSD, Decky ... to expand your horizons !  xD

 

Firstly, the 'imperfect analogue signal ' doesn't stop at 20kHz - the way a CD does.  Have a look at some cart specs - a top end range specced to 50kHz is not uncommon.

 

Secondly, if you run active speakers then you are probably into a digital XO/room EQ environment.

 

Andy

 

 

I am all for for expanding my horizons Andy - with or without chemistry but I think you misread my post. I did say that you are limiting the bandwidth by digitising the analogue signal, since that the original signal indeed has a bandwidth of 50Khz or more . Even 192Khz sampling at the ADC level is not really a great substitute. 

 

I do run active speaker but I am definitely not into digital XOs or room EQs. But whoever wants to run those, then OK - I can see the point, but in that case you are already triple processing your signal anyway. Adding a turntable to the mix makes very little difference. 

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1 hour ago, Decky said:

 

I am all for for expanding my horizons Andy - with or without chemistry but I think you misread my post. I did say that you are limiting the bandwidth by digitising the analogue signal, since that the original signal indeed has a bandwidth of 50Khz or more . Even 192Khz sampling at the ADC level is not really a great substitute. 

 

 

Mmmm, your understanding of 'things' seems to be vastly different to mine, D.  :huh:

 

AIUI, 192kHz sampling has a Nyquist frequency of 96kHz - vastly higher than my Maggie ribbons, which are specced to 40kHz ... which is already higher than most tweeters.  So 192kHz is not really that useful - your tweeters won't be able to take advantage of it.

 

96kHz, however, has a Nyquist frequency of 48kHz - so comparable with my ribbons and does not limit them in any way.  And it also delivers all that the vinyl source can provide.

 

1 hour ago, Decky said:

 

OK - I can see the point, but in that case you are already triple processing your signal anyway. Adding a turntable to the mix makes very little difference. 

 

 

Don't see where 'triple processing my signal ' comes from?

 

Given I need to input a digital signal into my miniDSP - which provides me with HP/LP filters for my active spkrs (and provides the delay required to  integrate subs) plus very helpful room EQ:

  • the A2D converter on my phono stage is a single transfer to digital (at a higher quality than that provided by the chips that miniDSP use).
  • my CDP and DAB+ tuner are already in digital format - so no transfer is required.
  • then I have a D2A transfer to feed my amplifier channels.

Given implementing subs properly requires delay to be applied to the Maggies (the subs are about 1.5m further away from my ears than the Maggie bass panels) ... I cannot do this in the analogue domain.  I could use analogue active XOs - and no subs (which is what I used to have) - but the move to subs & digital has delivered a significant improvement in my listening.

 

Andy

 

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Thanks for the inputs - good additions to the list:

  • REM looks excellent - likely overkill for mid-level vinyl set up but put it into consideration as it wouldn't be the weakest link.
  • I had reviewed the Puffin but somehow missed the digital out options!! Looks like it would fit well.  Do you know if the optical out is 48kHz as per the DIY SPDIF out comments.

Set up wise I am similar chain to Andy.  So would be phono A2D and then digital into miniDSP along with CDP and Roon / FLAC Library / Streaming.  Then on to Kii's as AES/EBU and their built in DSP and final DAC.  Kii DSPs in high quality mode add around 100ms processing so have to delay sub.
Sounds like the other question is why have all the convenience of digital and still retain the ceremonies of manual vinyl.  It still sounds great!  🙃🙃

Gibbo

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4 hours ago, andyr said:

 

Mmmm, your understanding of 'things' seems to be vastly different to mine, D.  :huh:

 

AIUI, 192kHz sampling has a Nyquist frequency of 96kHz - vastly higher than my Maggie ribbons, which are specced to 40kHz ... which is already higher than most tweeters.  So 192kHz is not really that useful - your tweeters won't be able to take advantage of it.

 

96kHz, however, has a Nyquist frequency of 48kHz - so comparable with my ribbons and does not limit them in any way.  And it also delivers all that the vinyl source can provide.

 

 

Don't see where 'triple processing my signal ' comes from?

 

Given I need to input a digital signal into my miniDSP - which provides me with HP/LP filters for my active spkrs (and provides the delay required to  integrate subs) plus very helpful room EQ:

  • the A2D converter on my phono stage is a single transfer to digital (at a higher quality than that provided by the chips that miniDSP use).
  • my CDP and DAB+ tuner are already in digital format - so no transfer is required.
  • then I have a D2A transfer to feed my amplifier channels.

Given implementing subs properly requires delay to be applied to the Maggies (the subs are about 1.5m further away from my ears than the Maggie bass panels) ... I cannot do this in the analogue domain.  I could use analogue active XOs - and no subs (which is what I used to have) - but the move to subs & digital has delivered a significant improvement in my listening.

 

Andy

 

 

There is way more to ADC or DAC signal sampling than the Nyquist theorem; dithering, noise shaping, jitter control etc. 

 

Triple processing - your source is an analogue signal and it is sampled and converted by an ADC, then the digital signal gets into a DSP unit to get filtered and altered as required or desired and then passed through a DAC to get out again as an analogue signal to be amplified. To be fair, modern FPGAs will have ADCs inbuilt in them but sometimes their quality and speed is not really up to scratch so the signal acquisition is done elsewhere.  It all of that chain of analogue to digital and back to analogue processing, there are a number of different power supplies and clocks which can have larger or smaller contribution to jitter. On top of that, the key aspect of the whole signal processing chain is your software implementations that can make or break the whole system. Everything is just way to messy for my taste, that is all. I do not have any doubts that it can be done correctly. 

 

Back to the topic - dealing with black discs for me is a thing of a ritual and simplicity. I try to put as little electronics between the groove and the speaker driver as possible. I am maybe irrational and overly purist - but that is my experience of this illness we call audiophilia.  

 

 

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10 hours ago, Decky said:

What is next - recording FM radio on a cassette tape and than digitising that into 24bit PCM stream

Your example begs the question why one would bother to employ a cutting head in order to be able to press a vinyl disc and extract sound from the vinyl groove using a stylus and cartridge, when the sound could simply be left in the digital domain (given that that is the form music will be mastered in today in the recording studio, with very rare exceptions).   Anyway I'll leave that hot topic alone.

 

As regards cassette tape, the imperfections of that technology (including high noise, high THD and IMD, wow and flutter) would I suggest predominate over any limitations of 24 bit 48kHz or 96kHz stereo stream, as produced by even a very most modest 24-bit audio ADC sold today.  It would indeed make little sense to interpose cassette tape technology. Far better to capture the FM sound using a device that produces the audio digitally to begin with (chips exist that process an incoming FM radio frequency signal entirely in the digital domain, and create a digital LPCM stream). Or if using an "old school"  FM tuner with analogue output only, far better to capture that analogue audio directly with a 24-bit ADC, even a very cheap one, than to fiddle with interposing an audio cassette deck. Audio cassette decks though they were sometimes considered more convenient than vinyl discs (especially in portable devices) were superseded both in sound quality and convenience by CDs. 

 

This thread though presupposes that the music has already been transferred to vinyl and seeks an effective way of getting that [back] to a digital version of the music.  ADC technology is pretty mature and I rather think the OP could get good results without spending a lot of money.  The unavoidable harmonic distortion in the signal from the cartridge, and the groove noise, should predominate over the very small distortion and noise introduced by even a cheap ADC.  (Imperfections introduced by a preamp used to amplify and equalize the signal from the cartridge, would hopefully be minor, or negligible. ) 

Edited by MLXXX
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16 minutes ago, sir sanders zingmore said:

The OP has kiis. 
Kiis require a digital input. 
End of story 

 

Excellent point, Trevor!  :thumb:

 

53 minutes ago, Decky said:

 

Back to the topic - dealing with black discs for me is a thing of a ritual and simplicity. I try to put as little electronics between the groove and the speaker driver as possible. I am maybe irrational and overly purist - but that is my experience of this illness we call audiophilia.  

 

 

I notice you said speaker driver (no 's'), D.

 

I presume your spkrs must be what is commonly known as 'full range' - ie. a single driver ... no XOs?

 

If so - yes, that is certainly "purist".  But not satisfactory, in terms of delivering music, IMO.

 

Andy

 

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11 hours ago, gibbo9000 said:

The $50 to $80 48kHz/96kHz consumer electronics store style - I bought one for testing and not impressed

It will be interesting to see whether what you eventually end up with is very noticeably better for your ears.   You may find that the vinyl  disc and its cartridge are by far the prime determiners of the sound quality of the signal fed to your active speakers. In other words, various different ADCs may be near transparent and make little difference.

Edited by MLXXX
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39 minutes ago, sir sanders zingmore said:

The OP has kiis. 
Kiis require a digital input. 
End of story 

I feed my Kii's a digital signal(s) (through the kii control) which then transfers the signal to the kii's via ethernet. I then have my analogue signal connected directly to the kii's which internally do the conversion from analogue->digital.

 

So if you choose, you can feed a phono (or other analogue signal)  directly into the kii's.

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8 hours ago, andyr said:

 

Excellent point, Trevor!  :thumb:

 

 

I notice you said speaker driver (no 's'), D.

 

I presume your spkrs must be what is commonly known as 'full range' - ie. a single driver ... no XOs?

 

If so - yes, that is certainly "purist".  But not satisfactory, in terms of delivering music, IMO.

 

Andy

 

I did not take you as a typo-nazi-purist type. I guess we are all different. Unfortunately, I still do not employ a proof-reader for my online posts.  Maybe one day if I start getting payed as an SNA influencer - times are strange - after Trump's and ScoMo's reigns anything is possible. 

 

...and nope, wrong again. Just analogue active X-overs. SGR CX3Bs and Dynaudio BM5 Mk3s. I also agree with you regarding "full range" speakers - rarely full enough range-wise and even less so satisfaction-wise.  

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8 hours ago, MLXXX said:

It will be interesting to see whether what you eventually end up with is very noticeably better for your ears.   You may find that the vinyl  disc and its cartridge are by far the prime determiners of the sound quality of the signal fed to your active speakers. In other words, various different ADCs may be near transparent and make little difference.

 

And all DACs sound the same, too?  :)

 

Andy

 

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9 hours ago, MLXXX said:

Your example begs the question why one would bother to employ a cutting head in order to be able to press a vinyl disc and extract sound from the vinyl groove using a stylus and cartridge, when the sound could simply be left in the digital domain (given that that is the form music will be mastered in today in the recording studio, with very rare exceptions). 

 

 

Exactly my point - most of the music that I listen to these days can be purchased as high res digital or on vinyl (or both). If one is using a purely digital system (at least from the user's signal processing perspective) the simplest (and best IMHO) way would be to stay in the original digital master space and don't bother with black discs.  

 

My FM recording comment did carry a "SARCASM" label. 🙃

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Like food, I prefer my audio with less processing.....I don't like to strip out the goodness :D

 

But for your needs/wants the Behringer SRC2496 is a cheap option in AD/DA, not sure if it has all you need but for the cost it is versatile.

https://www.storedj.com.au/behringer-ultramatch-src2496-24-bit-96khz-a-d-d-a-converter

 

Cheaper here https://djcity.com.au/product/behringer-src2496-sample-rate-converter/

Edited by muon*
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11 hours ago, MLXXX said:

It will be interesting to see whether what you eventually end up with is very noticeably better for your ears.   You may find that the vinyl  disc and its cartridge are by far the prime determiners of the sound quality of the signal fed to your active speakers. In other words, various different ADCs may be near transparent and make little difference

11 hours ago, MLXXX said:

ADC technology is pretty mature and I rather think the OP could get good results without spending a lot of money.

That is exactly what I am trying to work out.  My current 'benchmark' is the Schiit Jil, but it's output constraints mean I need to run it through a Raspberry Pi into USB on my miniDSP pre-amp.  That is OK in short term but not something ideal longer term.  Against that the $70 version sounds a little 'harsh' - a bit hard to describe but not as smooth as the Jil, or as clean on transients.  I would almost say it sounds digital.  So in my Goldilocks dilemma of ADC's it is bit too low end to my ears.  It is currently attached to my Cassette Deck output - but marginal in that role as well.

 

10 hours ago, wikeeboy said:

So if you choose, you can feed a phono (or other analogue signal)  directly into the kii's

I have tried that and it is pretty good.  The shortfall for me is I have gone the poor mans BXT route and added a sub via miniDSP, along with miniDSP presets to manage XO at 30, 50 or 80Hz along with slight bass boosts / tidy up with Dirac.  In my large listening room that helps the Kiis, and direct analogue input to them bypasses that.  And for me they are 4 metre RCA runs to each speaker by the time they go for top of cabinet, down to floor, through rats nest of wring and up to Kii's. 

 

Will take a look at the Behringer options as well - looks like there are more options available in the professional audio world.

Edited by gibbo9000
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6 minutes ago, gibbo9000 said:

Against that the $70 version sounds a little 'harsh' - a bit hard to describe but not as smooth as the Jil, or as clean on transients.  I would almost say it sounds digital.  So in my Goldilocks dilemma of ADC's it is bit too low end to my ears.  It is currently attached to my Cassette Deck output - but marginal in that role as well.

That is indeed unfortunate. 

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