Digital output cartridge

Carlman · « **on:** 8 Sep 2005, 02:57 am »

Is there such a thing made today? I'd like to send a digital signal directly from the cartridge to a TacT digital integrated. This way I bypass the need for a phono pre and digital conversion card for the amp.

I spoke to a fellow audio enthusiast on the phone and he made mention that a digital cartridge existed at some point... and I vaguely remember reading something about it but I have never seen one. Neither of us could remember any details, though.

So, I'm all ears! Thanks!

randytsuch · « **Reply #1 on:** 9 Sep 2005, 04:22 am »

Hi Carl,
Not sure how you could get digital output out of a cartridge.
It would need to have an A to D in it, and it would be tough to fit one in a cartridge, then you have to power it too.

Somewhere, you need to do an analog to digital conversion. I would think the tact could do the RIAA equalization in the digital world, so you would not need a phono stage, but if there is not a big demand for it, then there is no reason for Tact to develop it.

Randy

Dan Driscoll · « **Reply #2 on:** 9 Sep 2005, 05:32 pm »

Maybe he was thinking of the laser pick-up turntable? IIRC, several versions of the laser TT had a digital output.

I'm not aware of any mechanical cartridges having a digital output. Randy nailed it, you could not get an ADC into anything like a modern phono cartridge. You could possibly do the ADC after the wires exited the arm, on the plinth.

Carlman · « **Reply #3 on:** 9 Sep 2005, 06:17 pm »

Thanks, fellaz. I kind of figured as much.. and didn't think it made a lot of sense.

I wish TacT had a phono setting on their ADC card... But you are likely correct in thinking about demand determining development. There's probably not too many people keeping a turntable purely for their wife.

-C

Carlman · « **Reply #4 on:** 9 Sep 2005, 08:02 pm »

I asked this same question over on AA and it appears I am not insane.

Here it is:

For more info...

EDIT:
I contacted this company and here's the response:

Quote from: Ralf Ballmann

For futher details you may refer to our website www.behold-highend.de

you would need the following components:

MCA768 AD-Converter on the headshell
MCK768 MasterClockUnit to drive the MCA768
APU768 main unit housing
SDI7678 module to receive the MCK768 audio data
DIO768 module to transmitt the audiodata in S/PDIF format to your TacT

but i must admitt that this will perform highest quality until the audio
signal will enter the TacT due to the fact that the 24Bit/768kHz signal will
be decreased in quality this way. to keep it at the behold level you should
use our BPA768 amplifier or a pair of DAC768 to drive a very high quality
analogue final stage amplifier ...

rgds Ralf Ballmann

JoshK · « **Reply #5 on:** 10 Sep 2005, 02:09 am »

Can the TACT be programmed to add a special "curve" to the mix on a preset maybe? You could do it that way maybe. I actually asked TACT about it long ago and was told no, but now with 3rd party software, it might be doable.

In fact, I was thinking I should invent and take to market a box that would take the low level cartridge output, convert to digital, apply the RIAA curve or other type of curve (computer configurable, maybe with assignable presets) in the digital domain, add some gain to the digital signal if needed and then S/PDIF out. Kind of a specialized ADC. I think it might have a niche for those of us who use digital system with a TT still. Or even archivers, etc.

Carlman · « **Reply #6 on:** 10 Sep 2005, 04:34 am »

Josh,
I think something like that exists, the B&K Phono 10d.
I'm having a hard time finding a price for it, though... Someone on AA posted it was around $400.... I don't know, though. It's cheaper than buying the ADC for the TacT... and does RIAA... and doesn't require me to figure something out.

Probably doesn't sound great but likely not bad either...

-C

JoshK · « **Reply #7 on:** 11 Sep 2005, 12:40 am »

That one does the curve in the analog domain, so it is basically just a phono with built in *probably cheap* ADC. Not exactly the same solution and I'd fear it would be of lesser quality than you and I were looking for.

Carlman · « **Reply #8 on:** 11 Sep 2005, 12:50 am »

Quote from: JoshK

That one does the curve in the analog domain, so it is basically just a phono with built in *probably cheap* ADC. Not exactly the same solution and I'd fear it would be of lesser quality than you and I were looking for.

Damn I hate reality sometimes.

(I feel certain you are correct.) If I did buy that 10d phono pre, I might as well keep my old Sony TT and a cheap cartridge... and sell the Pro-Ject and Dynavector... Every day I get closer to giving up the vinyl thing. I'm going through all my records tomorrow to see how many I'd actually want to hear... and selling the rest. If the collection is less than a couple dozen, I may just ditch the hobby...

not sure how I feel about it yet.

Dan Driscoll · « **Reply #9 on:** 12 Sep 2005, 04:39 pm »

Quote from: Carlman

I asked this same question over on AA and it appears I am not insane.

Here it is:

For more info...

I see several problmes here. #1 is that it isn't really a digital output, the ADC is outboard of the cart. The cart still outputs analog, it just gets converted to digital before it is sent down the tonearm wires. I mentioned putting the ADC in the plinth, they just moved it a little closer by putting on top of the headshell.

#2, the ADC is open and unshielded, which is a good way to pick-up noise.

#3, you probably need to use their tonearm or modify a standard tonearm to mount the ADC board.

#4, to power the ADC board they have to be running DC power (5V?) up the tonearm. Since it is DC I'm not concerned about it causing problems with the digital signals going back down the arm, even though I'm sure the wires aren't shielded. However, I would be concerned about the digital wires inducing noise into the DC power lines.

I used don't see much practical use for this, althoug it is an interesting concept. But in the real world I'm pretty sure an outboard ADC would produce higher quality sound than anything on a tonearm or even in the plinth, and probably for less cost.

JoshK · « **Reply #10 on:** 12 Sep 2005, 04:52 pm »

I agree with Dan on that solution. I think the most practical "low hanging fruit" solution is to take standard cartridge ouptut into your current phono stage and add a quality ADC (pro audio does this better) to the stream.

I think my proposed solution would be a very interesting one but would need a lot of revisions before it could compete on the level of current products getting you to this end. I do like the ability of being able to change the curve on a whim in the digital domain rather than having to rebuild the analog circuit. Apparently there are now inexpensive and powerful DSP chips from TI that could do this.

sts9fan · « **Reply #11 on:** 12 Sep 2005, 05:18 pm »

I really have no clue about most of this stuff but this does not seem to make much sense to me. Isn't the whole reason people still use TT's is because its analog? Why would you want to pay thousands of dollars for a TT and then convert the signal to digital? I understand the TacT does a bunch of neat stuff but doesn't this defeat why you have the TT? Again I have no clue so you can disregard this post if you want..

woodsyi · « **Reply #12 on:** 12 Sep 2005, 07:17 pm »

Quote from: Carlman

Every day I get closer to giving up the vinyl thing. I'm going through all my records tomorrow to see how many I'd actually want to hear... and selling the rest. If the collection is less than a couple dozen, I may just ditch the hobby... not sure how I feel about it yet.

Give it up. It's not worth it -- noise, lack of dynamics, short playing time, can't replay, cleaning BS, etc. Stick to your SB2 and send the records to me. I will pay shipping.

I will make sure they are listened to.

I am going the other way. I just sent my Basis motor to get 78 pully mod, ordered Grado 78e, and will get a Bugle pro to do eq for the 78's. Can't wait to try some of these going back to 1902.