Denon DA-500 Tubed DAC clocking

[DutchMark]

Hi All,

After building on of Guido Tents oscillators in my CD6000 OSE, I am very happy with the result, I noticed that its hard to really improve the sound of the CD6000. The used HDAM doesn't sound that great. When short the audio ouput caps, the sound becomes harsh and overly analytic. What I need here is a tubed output stage !!!!

Since I do not want to molest the CD6000 too much, I descided to do this mod on a Denon DA-500 instead. This is a PCM 1702 DAC that I need to upgrade here and there. I have already chosen some components like, sowter I/V conversion, 6922 tubes.

My question is how to get the clocking right in this DAC. I have the Guido Tend oscillator in the CD6000. Te DAC applies a simple YM3623, which really isn't that stable. What are my alternatives, and what will perform best:
- Re-clocking (schematic?) Does this require a low jitter clock in DAC, CD or both?
- Narrow-band PLL (schematic?)
- Clock sharing with CD player? (clock in CD or in DAC?)
- other options ???

Wha are the draw-backs of re-clocking ? Does bitslip ocur, and whats the effect in the audio domain?

Who can help me with this type of question ? I appreciate all advise.

Kindest regards,
Mark Paanakker

[Guido Tent]

Originally posted by DutchMark
Hi All,

After building on of Guido Tents oscillators in my CD6000 OSE, I am very happy with the result, I noticed that its hard to really improve the sound of the CD6000. The used HDAM doesn't sound that great. When short the audio ouput caps, the sound becomes harsh and overly analytic. What I need here is a tubed output stage !!!!

Since I do not want to molest the CD6000 too much, I descided to do this mod on a Denon DA-500 instead. This is a PCM 1702 DAC that I need to upgrade here and there. I have already chosen some components like, sowter I/V conversion, 6922 tubes.

My question is how to get the clocking right in this DAC. I have the Guido Tend oscillator in the CD6000. Te DAC applies a simple YM3623, which really isn't that stable. What are my alternatives, and what will perform best:
- Re-clocking (schematic?) Does this require a low jitter clock in DAC, CD or both?
- Narrow-band PLL (schematic?)
- Clock sharing with CD player? (clock in CD or in DAC?)
- other options ???

Wha are the draw-backs of re-clocking ? Does bitslip ocur, and whats the effect in the audio domain?

Who can help me with this type of question ? I appreciate all advise.

Kindest regards,
Mark Paanakker

Hi Mark

You need a low jitter clock at your DAC. There are indeed several options

- Place masterclock in DAC and feed back to drive. In this case both clocks should be equal, to come to a simple implementation. Otherwsie you need dividers/ multipliers. In addition you need a proper interface (buffer, cable, receiver)

- Keep it as it is and place a decent PLL circuit in your DAC, which reduces jitter from the Yamaha. An example is my XO DAC circuit.

- Asynchronuous clocking. You need a much higher clock frequency, and I still do not get how it works. Drawback is that the DAC chips are fed with much higher RF than required.

hope this helps

[Barry Loef]

Very interesting.

Soon I will receive my DA-500 and I do want to improve the DAC with other components and circuits. This topic is a great start for me to begin the modding

Greetings,
Barry

[Barry Loef]

De DA-500 has been arrived!

Sounds good, for now (compared with my LG dvd player).

[Fin]

Originally posted by Guido Tent

You need a low jitter clock at your DAC. There are indeed several options

- Keep it as it is and place a decent PLL circuit in your DAC, which reduces jitter from the Yamaha. An example is my XO DAC circuit.

I have recently acquired an Audio Alchemy Dac In The Box (DITB) and an XO Dac modules (without VCXO) with matching XO Supply. The DITB uses CS8412, YM3434 and two AD1860 dacs. I would like to use the XO Dac with this DITB but do not know which frequency VCXO to order for it. The information on the net that I can find mentions values ranging from 11mHz right up to 20mHz. Any help would be appreciated.............

[Fin]

Here is the schematic...and on closer inspection...it looks like YM3433 instead of YM3434.

DITB Schematic

[Guido Tent]

Originally posted by Fin
Here is the schematic...and on closer inspection...it looks like YM3433 instead of YM3434.

DITB Schematic

Hi

The YM is clocked with pin 12 from the 8412. this clock is 2.8224 MHz and sets the jitter in the rest of the chain.

I do not know the 1860 by heart, but it is likely the conversiontakes place using the clock at pin 12: Could you measure that frequency ?

best

Guido

[Fin]

Hi Guido

Thanks for your reply.

From various other sites and threads I have discovered that AD1860 is similar to AD1861 and identical to PCM61. Not sure if that helps.......

From the datasheets of these similar chips, the schematic of the DITB and what you say - it looks like the the YM3433 is clocked at pin 5 by BitClk from pin 12 of CD8412. Pin 12 of M3433 then feeds BCO to the two AD1860 chips. The schematic shows the CLK input on AD1860 as being on pin 5 - but the datasheet shows it a being on pin 12. I would think that the datasheet is more correct.

My measuring equipment consists of what you see in my avatar :-)

[Guido Tent]

Originally posted by Fin
Hi Guido

Thanks for your reply.

From various other sites and threads I have discovered that AD1860 is similar to AD1861 and identical to PCM61. Not sure if that helps.......

From the datasheets of these similar chips, the schematic of the DITB and what you say - it looks like the the YM3433 is clocked at pin 5 by BitClk from pin 12 of CD8412. Pin 12 of M3433 then feeds BCO to the two AD1860 chips. The schematic shows the CLK input on AD1860 as being on pin 5 - but the datasheet shows it a being on pin 12. I would think that the datasheet is more correct.

My measuring equipment consists of what you see in my avatar :-)

Hi Fin

I'd suggest to start with XO DAC 2.8224 MHz, interrupt line 12 from the 8412. Pin 12 goes to XO DAC input, XO DAC output generates the new clock.

best

Guido

[Fin]

Hi Guido

Just checked the Tentlabs site and you have some 2.8224mHz VCXOs......:-) I'll send you an email in a while.

Here is a link to the site that was causing me some confusion:
Jon's Opinion
He mentions a 20mHz crystal. Should this be removed?
Also - can I directly clock the AD1860 chips using the the XO DAC?