Which ADC for Phono Signal into S/P-DIF or Toslink?

[wgh52]

Hi folks!

I want to integrate my Phono Signal into a digital Stereo chain without PC by adding an ADC before or as part of the DSP-DAC stage.

So, in order to not distract the "Integrating a turntable into a digital system" thread, I'm starting this thread to dedicate it to my own project

A short recap of the situation and project:
- 3-Way or 4-Way active Speakersystem with DSP x-over.
- DSP has only digital Inputs: coax S/P-DIF, Toslink, bluetooth, USB
- I do like to listen to LP records occationally
- Looking for an ADC appropriate for Phono Preamp Output AD conversion
- Budget is up to 200€ for ADC box (or board).
- PC is optional signal source, it is not and will not become integral part of the signal chain

I have learned that input signal range is a potentially critical thing, but in light of <60dB dynamic range I wonder how much to invest and which technology to use in order to not "damage" the phono signal.

As a first step I have bought a PCM1804 based ADC board from Audiophonics but have no idea if this thing "fits the bill" of requirements for a decent phono ADC:
- Inputs are cinch unbalanced
- Input OPAs are 5532s, the ADC is the old TI PCM1804
- 24.576MHz clock generator is on board for up to 24/192 (I will use 24/96)
- ADC Outputs are coax S/P-DIF and Toslink, no USB
- The board's back side shows (marked) I²S solder bumps (not mentioned in the data sheet)
- The board can run as clock master or clock slave

So please give any feedback
- How do you approach the Phono ADC case?
- Which approach should I take?
- Where are pit falls?
- Does my integration idea (picture above) make sense?
- Which factors do I need to observe/optimise for best phono-ADCing quality?
- Is there a viable chance to take advantage of the DSP internal 24.576MHz clock or even its I²S?
- Which ADC or ADC board do you consider more/most appropriate for phono ADCing and why?

Thanks and Regards,
Winfried

 

[DVDdoug]

Probably any DAC is better than the record itself. Same for your phono preamp unless it has excessive hum or hiss.

- How do you approach the Phono ADC case?

Companies that sell electronic components usually sell "project boxes". Here are some from Jameco Electronics. (Their search feature isn't very good and it turned-up some unrelated items.)

That board looks like it has a "front and "back" so you might not find a perfect fit... You might have to "extend" the connectors or something...

Some people 3D print their enclosures.

 

[Balle Clorin]

Parks Audio Puffin digital RIAA with Toslink out to your digital system . Only one ADC in the chain . Worth every penny even if it is

 

[wgh52]

Probably any DAC is better than the record itself. Same for your phono preamp unless it has excessive hum or hiss.

Conceeded (you probably mean ADC, though...), but which ADC can you recommend from your listening experience? Just "any"? That sounds too simple to me as vinyl lover...

Companies that sell electronic components usually sell "project boxes". Here are some from Jameco Electronics.... That board looks like it has a "front and "back" so you might not find a perfect fit... You might have to "extend" the connectors or something... Some people 3D print their enclosures.

This is well understood, we have good sources here in Europe as well, but a case for the ADC is of lesser concern at this time as I'm looking for a good ADC.

Thanks and regards,
Winfried

 

[wgh52]

Parks Audio Puffin digital RIAA with Toslink out to your digital system . Only one ADC in the chain . Worth every penny even if it is

Parks Audio is unavailable in Europe and even if it was: I love the Lehmann BC SE II (which I modified/improved), that already puts out a good RIAA equalized line level signal, so I will keep this amp and look for a decent ADC. But which one?

Thanks,
Winfried

 

[JP]

That sounds too simple to me as vinyl lover...

It's that simple - any engineered ADC is going to do just fine.

 

[Balle Clorin]

Parks Audio is unavailable in Europe and even if it was: I love the Lehmann BC SE II (which I modified/improved), that already puts out a good RIAA equalized line level signal, so I will keep this amp and look for a decent ADC. But which one?

Thanks,
Winfried

No it is not unavailable, I bought it directly from Parks Audio to Norway, no problem , it was also sold by eBay to Europe. But demand is now larger than supply next 6 months. Any USB ADC will outperform vinyl if that is what you want

 

[morillon]

USB Phono Plus – Project Series – ART Pro Audio

artproaudio.com

 

[Mr. Widget]

Parks Audio is unavailable in Europe and even if it was: I love the Lehmann BC SE II (which I modified/improved), that already puts out a good RIAA equalized line level signal, so I will keep this amp and look for a decent ADC. But which one?

If you can swing $500, the standard w/digital outs miniDSP Flex is an excellent ADC. I needed a fully transparent ADC and that is the route I went. Outside of fairly costly studio gear or messing around with computer sound cards, most ADCs that I found were very inexpensive plastic boxes with poor or no specifications.

There is the argument that between cartridge output, RIAA filters and preamps you are far from flat, but why compound their errors?

 

[dlaloum]

A perfectionist perspective:

The key cautions you need to watch for are peak output levels and peak input levels - you want to ensure that the ADC never under any circumstance clips...

The worst case that you need to cater for is the pops/clicks that are unavoidable, and can peak at 20db above the peak level of the recording on the LP...

So you need to have some form of preamp/level adjustment in the chain to be able to adjust the analog signal up/down before the ADC, so that you can properly digitise it without clipping while also keeping it as far above the noise floor as possible.

This makes the available dynamic range, a key data point... - you sacrifice 20db to provide for the click/pop overhead, then given yourself circa 80db for the recording... you need to have a clean 100db of dynamic range - if you have an ADC with 120db of dynamic range, it gives you "room to move" and makes it easier to match up input/output levels.

So although I usually am wary of excess focus on SINAD for amps/receivers - for ADC's SINAD, Signal/Noise and Dynamic Range are totally key.

Although Pricey, things like the Mytek Brooklyn ADC, with a claimed 130db dynamic range, can be a lifesaver in this sort of role.

Years ago, I purchased a Mytek Stereo96 ADC for exactly this purpose... at the time it was the best I could find at an almost reasonable price, and it gives me 117db of dynamic range.... it still required careful adjustment of inputs/output levels for best results. (THD+N was is only 105db = SINAD)

I'm pretty sure you can match my old Mytek for 1/4 of what I paid for it 10+ years ago...

Amirm has tested a bunch of ADC's over time - so there is a resource here you can lean on - but you will quickly find that achieving more than 100db SINAD is a challenge, and one that many ADC's fail on - and many of those that succeed, are not cheap.

 

[Jas0_0]

Since your cartridge is MC, have you considered using an audio interface with two mic inputs for AD conversion, then doing the RIAA equalisation digitally in the Flex?

It would reduce your box count as you wouldn’t need a separate phono pre and ADC and they can be picked up second hand for far less than €500.

For example I use an RME Fireface for my turntable. It has a high quality ADC and mic amps. You’d need to change your tone arm cable to balanced XLR (which has the added benefit of allowing a longer cable).

Your cartridge recommends a loading of simply greater than 200 ohms, so this wouldn’t be an issue with a good interface as their input impedances are typically in the tens of kohms.

If this seems like a viable option, check the Flex review thread here for details of how to do digital RIAA.

 

[morillon]

- Budget is up to 200€ for ADC box (or board).

as a reminder...
etc etc
good records.. because the essential anyway..
;-)
(and a cool approach to cleaning these..)

 

[Jas0_0]

I bought my RME Fireface for £190 used.

The unneeded Black Cube could be sold. A used one recently fetched £450 on eBay.

XLR tone arm cable £50.

Could save €200.

 

[wgh52]

Hi Balle,

.... I bought it directly from Parks Audio to Norway, no problem , it was also sold by eBay to Europe....

Well, I want a European source with warranty.

USB Phono Plus – Project Series – ART Pro Audio

artproaudio.com

I was actually not into buying a new Phono pre, but will keep note of the offer which has a dealer in Germany.

@ Mr. Widget

... the standard w/digital outs miniDSP Flex is an excellent ADC...

This is waht I thought about first as well, but I need the 4 Stereo Outputs of the Flex Eight and adding both is unfortunately way off the map budget wise. BTW: In Europe the Flex series is in the 700€ league (incl. VAT).

....There is the argument that between cartridge output, RIAA filters and preamps you are far from flat, but why compound their errors?

Please consider that I do like the sound quality of my current phono set up and want to feed this through to the Speakers (as I actually did with the DEQX PDC so far).

@ dialoum:
Thanks a lot for the comprehensive and educative...

... perfectionist perspective: ....

which I much appreciate! So far I used a DEQX PDC which has an AD converter successfully which sounded better after I modified the internal AD clock (clocking the PDC's AD converters) and with a Tent based oscillator solution. Interestingly enough I did not experience overload so far, but understand the mechanisms and am looking for level adjusts in my future solution.

@ Jas0_0

Since your cartridge is MC, have you considered using an audio interface with two mic inputs for AD conversion, then doing the RIAA equalisation digitally in the Flex?... It would reduce your box count ....

If this seems like a viable option, check the Flex review thread here for details of how to do digital RIAA. ... The unneeded Black Cube could be sold. A used one recently fetched £450 on eBay...

My MC cartridge is a Benz ACE H, i.e. high output and othe cartridges are MM. But that aside, Flex based RIAA EQ is a thought I had as well, but that also needs an external ADC. I did not have a Stereo mic pre with ADC on the map yet. So, while the RME is outside of budget, because it is an overkill channel wise (had one years ago and the mixing software was a "drag" for me back then), I'll have a look at this option, though.

...XLR tone arm cable £50. ...

Changing the tone arm cable to XLR does not sound realistic with my Technics EPA-500 tone arm system on the SL-1000 II turntable.

@ morillion

it seems to me in the first place that it is for occasional use and not necessarily ultra
ambitious... not necessarily a "gas plant" etc. but if you already have a phono stage .. any correct sound card, line input, will do ...
;-)
(which cartdrige arm turntable ? what phono stage?)

Yes! I believe to have a decent phono set up with Technics SL-1000 II, EPA-500 and Lehmann BC SE II & PWX, listening to LP records occationally, mainly with friends or spouse. If or when I listen to records, I want really good quality, not necessarily looking for the absolute high end - that's true. Most of my LP records are not new, but occationally played and dry cleaned every time played, a washing machine has been outside of budget so far, despite desired...

Thanks a lot to all!
Winfried

 

[morillon]

for waiting

Swissonic HAD-1

Amplificateur de casque et convertisseur audio Avec connexion USB 2.0, Résolution: 24 bits 96 kHz, Sortie casque: jack 6,3 mm, Entrée stéréo analogique: RCA, Entrée numérique: S / PDIF, Sortie stéréo analogique: RCA, Sortie stéréo numérique: sortie...

www.thomann.de

or

Swissonic Converter AD 24/192

Convertisseur Convertisseur analogique vers numérique (S/PDIF), Résolution: 24 bits / 192 kHz, Sorties: 1x S/PDIF coaxial , 1x S/PDIF optique, Commutable en cours de fonctionnement (seulement 1 sortie active), Entrée: 1 stéréo cinch, Dimensions: 95...

www.thomann.de

;-)
easy to found in germany
pcm1804 like your idee.. but finish?


(even if there is plenty on the net, this little one is 40 euros, it will be fun to measure it)
but most of the delicate work is done at the level of your prephono...

 

[Hayabusa]

I have the 'old' SHD with A/D in and used it to connect my MM phono signal, worked perfect! Some bi-quads and a lot of gain

 

[LTig]

for waiting

Swissonic HAD-1

Amplificateur de casque et convertisseur audio Avec connexion USB 2.0, Résolution: 24 bits 96 kHz, Sortie casque: jack 6,3 mm, Entrée stéréo analogique: RCA, Entrée numérique: S / PDIF, Sortie stéréo analogique: RCA, Sortie stéréo numérique: sortie...

www.thomann.de

or

Swissonic Converter AD 24/192

Convertisseur Convertisseur analogique vers numérique (S/PDIF), Résolution: 24 bits / 192 kHz, Sorties: 1x S/PDIF coaxial , 1x S/PDIF optique, Commutable en cours de fonctionnement (seulement 1 sortie active), Entrée: 1 stéréo cinch, Dimensions: 95...

www.thomann.de

;-)
easy to found in germany

(even if there is plenty on the net, this little one is 40 euros, it will be fun to measure it)
but most of the delicate work is done at the level of your prephono...

I measured the corresponding DAC, FWIW.

 

[morillon]

the inverse
your... d-a..
here
a-d
;-)

 

[morillon]

Swissonic Converter AD 24/192 (ADC) Measurements

After the recent measurement I did for the unbranded ADC I got off eBay, to compare a friend borrowed me a relatively similar device by a thomann.de house brand - Swissonic Converter AD 24/192 that sells for about 40€: Basic features are mostly the same, except this one comes with a power...

audiosciencereview.com

found!

 

[LTig]

Swissonic Converter AD 24/192 (ADC) Measurements

After the recent measurement I did for the unbranded ADC I got off eBay, to compare a friend borrowed me a relatively similar device by a thomann.de house brand - Swissonic Converter AD 24/192 that sells for about 40€: Basic features are mostly the same, except this one comes with a power...

audiosciencereview.com

found!

ASR is a great place, really. And it seems both ADC and DAC perform in the same class - far from SOTA but transparent under most circumstances.