Turntable > Mic Pre > ADC > Mac > DAC > speakers - clock problem?

[Jas0_0]

Hi all,

If I were to play music from my turntable using the signal path in the thread title, would it cause a problem with clocking?

(In case you’re wondering, I send the signal to my Mac to do RIAA and room correction)

I currently use a separate mic pre into a one-box DAC/ADC, but would see significant cost benefits from changing.

I have to admit I don’t really know what clocking is, but the Pure Vinyl website has led me to believe that it becomes a problem if using a separate DAC and ADC.

Is that Pure BS?

Thanks!

James

 

[AnalogSteph]

Unless you find a way to synchronize the clocks of separate ADCs and DACs (e.g. wordclock I/O), they will drift apart eventually. At some point, that invariably results in a buffer underrun / overrun, likely made audible as a crack / pop.

Let's say we have a difference of 50 ppm, which is not unrealistic for two random crystal oscillators of average quality. That's 1 sample in 20000, or a good 7 minutes before a 1024 sample buffer runs out at 48 kHz.

You may want to outline your current equipment and what you mean by "significant cost benefits", maybe someone here will have a better idea.

BTW, is that an MC cartridge, or why are you using a mic preamp? Good ones tend to be in the ballpark of decent MC inputs, but they're not going to match the best ones (with "transistor grave" input stages) for noise. They are obviously not suited for MM cartridges due to low input impedance.

 

[Jas0_0]

Thanks Steph - just the answer I was looking for. Really appreciated.

You’re right, I’m using an MC cartridge. Currently into an AEA TRP mic pre - I figured ribbon mics and MC carts share similar needs. Gain is currently set to 68dB.

That feeds an RME ADI-2 Pro FS R - which also handles digital music from my Mac.

I bought both used and together they set me back about £1700.

I’m just wondering if it’s all a bit overkill.

 

[AnalogSteph]

Ah, just found your other thread.

Low cost USB audio interface with remote control?

Hi everyone, I'm hoping to take some money out of my system. I have an RME ADI-2 Pro FS R, which is excellent and does everything I want, but I can't help feeling it's a bit overkill for what I need - both in spec and function. Is there a cheaper alternative out there with a remote control...

audiosciencereview.com

I bought both used and together they set me back about £1700.

Which I imagine wasn't a bad deal considering that I bet the RME by itself was about that much new, no more than 2 years ago.

I’m just wondering if it’s all a bit overkill.

Well... are you using any of the RME's more advanced features (PEQ, loudness, digital I/O, whatever) or the headphone out? If not, that could be replaced by a substantially cheaper audio interface, even a lowly Focusrite Scarlett 4i4 3rd gen (or one of its bigger brothers). It just needs line-ins and -outs. You may need some new cabling (XLR to TRS and vice versa) but that won't break the bank. I would keep the TRP for the time being.

I can't imagine you'd have much trouble getting rid of the RME, given that it seems to be out of stock with its successor still several months out.

If you really need a remote on an audio interface you may be kind of screwed though. Maybe look at remote desktop solutions so you can control the Mac from a tablet or something?

 

[Jas0_0]

Yes the remote is a sticking point for home audio/TV use. Remote desktop is a good idea and would work for me, but I think the rest of my family would complain.

I think my only other option is the MiniDSP Flex.

If I sold the RME and bought a Flex, I'd probably recover about £600. I'd miss the RME's loudness function, but that's not a dealbreaker as I could just create a few EQ presets for different volume levels.

I could also lose all the fiddly software EQ on the Mac.

I think the Flex is the answer.

Thanks again for all your help.

 

[MCH]

Have you thought about streaming the turntable signal?

How to integrate your turntable/analog source in your streaming system - Step by step instructions for dummies

Hello all, I thought it would be good to put together some simple instructions to integrate a turntable, or any other analog source, into a 2022 wifi streaming environment. My own experinece tells me there are at least two reasons one would want or need to do this: 1. There is a tendency...

audiosciencereview.com

 

[OldHvyMec]

OP, What is a Mac? Mcintosh? I'm not understanding what you are doing at all.

I understand the MC transducer, and the fact you are using a turntable and the speakers. Why all the ADC & DAC, Mic pre?

More coffee might help me. What are you trying to do? Play records? It sure sounds like a lot of cables for a TT to get to a pair of speakers.
Just sayin'

 

[Jas0_0]

Have you thought about streaming the turntable signal?

How to integrate your turntable/analog source in your streaming system - Step by step instructions for dummies

Hello all, I thought it would be good to put together some simple instructions to integrate a turntable, or any other analog source, into a 2022 wifi streaming environment. My own experinece tells me there are at least two reasons one would want or need to do this: 1. There is a tendency...

audiosciencereview.com

Interesting suggestion. Not sure it solves my current dilemma but good to know it’s possible for the future.

 

[Jas0_0]

OP, What is a Mac? Mcintosh? I'm not understanding what you are doing at all.

I understand the MC transducer, and the fact you are using a turntable and the speakers. Why all the ADC & DAC, Mic pre?

More coffee might help me. What are you trying to do? Play records? It sure sounds like a lot of cables for a TT to get to a pair of speakers.
Just sayin'

Yes Mac = Macintosh computer. As stated in my original post I digitise the signal from records so I can perform digital room correction

 

[DVDdoug]

At some point, that invariably results in a buffer underrun / overrun, likely made audible as a crack / pop.

Are you sure about that? I might be more like "jitter" which tends to introduce little inaudible errors. If t was that bad he probably would have noticed by now...

And right... A moving coil cartridge should be OK but a standard moving magnet cartridge expects a 47K Ohm load. A typical mic preamp is around 1K and that will probably change the frequency response so the RIAA curve should be tweaked.

...Of course you could digitize your records. And there is software for cleaning-up any "snap", "crackle", and "pop". I've been able to make significant improvements but the results have never been "CD quality". I only digitize vinyl when the recording isn't available digitally... I'll take an MP3 from a digital source over digitized vinyl.

 

[AnalogSteph]

Are you sure about that? I might be more like "jitter" which tends to introduce little inaudible errors.

I mean, jitter in A/D and D/A would no longer tend to cancel, that's true, but that would hopefully be inaudible to begin with.

If t was that bad he probably would have noticed by now...

How so, if he hasn't changed anything about his setup yet?

 

[MaxwellsEq]

In complicated, multi-room and multi-building broadcast centres, accurate common clocks are essential, since there are hundreds of ADCs and DACs physically and logically separated.

If systems become unsynchronized, there are random audible clicks, splats and bangs.

 

[mdsimon2]

Macs have the ability to create an aggregate audio device, you should be able to combine the ADC and DAC in to an aggregate device and select one of them as a clock master. As I understand core audio will use resampling to account for clock differences between the ADC and DAC but I have not personally used this feature.

CamillaDSP also offers similar functionality, you can use a separate ADC and DAC and enabling rate adjust and async resampling will prevent buffer over/under runs.

Michael

 

[Jas0_0]

Macs have the ability to create an aggregate audio device, you should be able to combine the ADC and DAC in to an aggregate device and select one of them as a clock master. As I understand core audio will use resampling to account for clock differences between the ADC and DAC but I have not personally used this feature.

CamillaDSP also offers similar functionality, you can use a separate ADC and DAC and enabling rate adjust and async resampling will prevent buffer over/under runs.

Michael

This sounds promising - just found the link of how to do it. Seems fairly straightforward.

Create an Aggregate Device to combine multiple audio devices

With an Aggregate Device, you can use audio inputs and outputs from different devices at the same time with Logic Pro, GarageBand, MainStage and most other Core Audio-compliant applications.

support.apple.com

Thanks,

James

 

[OldHvyMec]

As stated in my original post I digitise the signal from records so I can perform digital room correction

Oh. I think I would have mechanically corrected the room and enjoyed the record. Just play a CD if your going to do that.

Macintosh = computer

Mcintosh = stereo gear.

When you stated Mac and used the terms turntable, RIAA and the rest, silly me thought Mcintosh with dual MM and MC phono inputs.
Sorry when I think music I think Valves and analog. Thoren TD124 - Decware ZP3 - Cary SLP-05 - Cary CASV12Rs - RMx Elixirs.
My subs right now are tuned with a gain control, position and soft putty. Again no digital. It is ALL point to point even the passive XOs
in the monitors.

I think it's called CavemanSoundProcessor CSP not DSP. Curtains, Helmholtz adjustable traps, first reflection points with SOME diffusion,
Speaker and sub location, location rugs, and a cannabis plant for diffusion. The plant is music dependent, it seems to work better with
Island music, Reggae, some Hip Hop and definitely, Rap. It seems to work when I'm watching the belly dancing competition too.

I do have a neat gadget I use for recording to a Reel To Reel. I also use it on the old broadcast TT like Russco. The Puffin by Parks Audio.
It is a nice compact unit for around 4-600.00 depends on the options you like. It's not a Decware, Herron, Mcintosh TOL photo pre
BUT it sure is cool with lots of options. The Mighty Puffin. The guy that made the thing is a nice guy too.
NO I don't know how it measures. Maybe ASR has the scoop. I like it for what it does. It's fun too.

Enjoy digitizing, brought to you by Mr. Analog from a time not quite gone by.

Regards

 

[MaxwellsEq]

I do have a neat gadget I use for recording to a Reel To Reel. I also use it on the old broadcast TT like Russco. The Puffin by Parks Audio.
It is a nice compact unit for around 4-600.00 depends on the options you like. It's not a Decware, Herron, Mcintosh TOL photo pre
BUT it sure is cool with lots of options. The Mighty Puffin. The guy that made the thing is a nice guy too.
NO I don't know how it measures. Maybe ASR has the scoop. I like it for what it does. It's fun too.

Parks Audio Puffin Review (Phono Stage)

This is a review and detailed measurements of the Parks Audio Puffin Phono Pre-amplifier. This is a special device in that it digitizes the cartridge output and then is able to perform a wealth of signal processing on the signal from pop and tick removal to RIAA equalization. The standard one...

www.audiosciencereview.com

"I have a soft spot for the Puffin as it is made locally and looks kind of cute. Its RIAA equalization is the most perfect I have seen in any phono stage which is the most audible thing. All the other filters and processing far outweigh anything that is out there and would make for a bunch of fun tweaking. Alas, not a fan of the high price with digital output. As far as I am concerned, that should be standard in the base price let alone incur a $200 penalty. Headroom is low as well and distortion is higher than pure analog phono stages. Then again, the LP medium has so much distortion that the latter point doesn't make any difference in reality.

Overall, I am going to put the Parks Audio Puffin on my recommended list but you may not."

The strongest concern is whether the headroom is sufficient

 

[OldHvyMec]

Thanks MaxwellsEQ I appreciate the information. I'm not what they call an Ahole-ic Autophile. BUT I am a nosey sort none the less.

I like facts first and almost everyone's opinion. The truth of it is, opinions and 5 dollars will get you a cup of coffee. Facts will tell you how
to make your own. I'm analog all the way and digital and humming in the shower and listening in the car. I don't care to much how I get
my tunes on. I'm glad I can still hear and enjoy music or NOT to tell the truth.

Close to The Victrola time of year. We'll see. Polish up a stylus or two. No I did not measure it. I can barely keep it wound up.
I know is has better sound than the New Wilsons if you take away the AC power. About 900k less too.

 

[Jas0_0]

Macs have the ability to create an aggregate audio device, you should be able to combine the ADC and DAC in to an aggregate device and select one of them as a clock master. As I understand core audio will use resampling to account for clock differences between the ADC and DAC but I have not personally used this feature.

CamillaDSP also offers similar functionality, you can use a separate ADC and DAC and enabling rate adjust and async resampling will prevent buffer over/under runs.

Michael

Just wanted to thank you again for this post.

As a result of this I replaced my RME Pro with an RME DAC, and the AEA TRP with an RME Fireface.

Your aggregate suggestion works perfectly, sound quality is the same and functionality is better.

It also saved me £750. So I owe you a beer.