This is probably basic stuff for people who grew up in the digital age, but I'm trying to catch up.
The player uses a M50423fp decoder chip that has SPDIF out, and also has a stand alone divide by two circuit in it. I have added a pulse trafo and use it as a transport and it works fine.
It actually uses a ceramic resonator instead of an XO and uses 8.4xxMhz. I was told by a clock supplier I could use 16.9xxMhz to reclock the SPDIF and use the divide by two circuit and run the player off of that at the correct freq.
Is this a good way to do it, will there be timing problems with a possible delay, or should I just reclock the player with an 8.4xx clock and try to reclock the SPDIF at the same freq.
Thanks in advance, Bill
The player uses a M50423fp decoder chip that has SPDIF out, and also has a stand alone divide by two circuit in it. I have added a pulse trafo and use it as a transport and it works fine.
It actually uses a ceramic resonator instead of an XO and uses 8.4xxMhz. I was told by a clock supplier I could use 16.9xxMhz to reclock the SPDIF and use the divide by two circuit and run the player off of that at the correct freq.
Is this a good way to do it, will there be timing problems with a possible delay, or should I just reclock the player with an 8.4xx clock and try to reclock the SPDIF at the same freq.
Thanks in advance, Bill
Hi Bill, If I fully understand what you are asking, are your concerns with clocking the player in multiple places from a single high quality external clock source?
In my TDA1541 player, I have a single high quality C2 clock from audioupgrades.co.uk which includes multiple buffered outputs. 2@xtal x1, 2@ /2 and 2@ /4.This clean feed replaces all the cascaded clock feeds to the decoder, filter and DAC chips.
In my experience, provided you use a single clock source (therefore ensuring clock timing alignment) you should be able to replace all the clocking feeds inside the player with clean independant feeds.
Looking at the datasheet, for your processor, there is a comprehensive clocking section. The master clock is redistributed by the processor.
I would not hesitate to install a single 'clean' master clock and independantly clock all relevant areas.
The data sheet for the chip is HERE
There are a couple of pictures showing the multiple clock feeds on my player HERE Middle picture shows the coax distribution.
In my TDA1541 player, I have a single high quality C2 clock from audioupgrades.co.uk which includes multiple buffered outputs. 2@xtal x1, 2@ /2 and 2@ /4.This clean feed replaces all the cascaded clock feeds to the decoder, filter and DAC chips.
In my experience, provided you use a single clock source (therefore ensuring clock timing alignment) you should be able to replace all the clocking feeds inside the player with clean independant feeds.
Looking at the datasheet, for your processor, there is a comprehensive clocking section. The master clock is redistributed by the processor.
I would not hesitate to install a single 'clean' master clock and independantly clock all relevant areas.
The data sheet for the chip is HERE
There are a couple of pictures showing the multiple clock feeds on my player HERE Middle picture shows the coax distribution.
Hi Ian,
I will try to address this as intelligently as I am able to. I have three different units I can use as a transport, but the old Philips CDM4/19 in the 502 pretty much much smokes them in the PRAT department with a simple pulse trafo output arrangement. It's not perfect in many respects, so I'm looking to improve the performance by reclocking the unit, in itself not a difficult task. What I'm asking, I guess, is actual reclocking of the SPDIF output at 2x the original freq of any benefit sonically, or is the use of a high quality clock in the unit enough of a benefit in itself. I will probably disable all the on board dac conversion circuitry as I will only use it as a transport unit. I just acquired a spare so I can experiment to my hearts content.
I hope I was coherent enough.
Best regards, Bill
I will try to address this as intelligently as I am able to. I have three different units I can use as a transport, but the old Philips CDM4/19 in the 502 pretty much much smokes them in the PRAT department with a simple pulse trafo output arrangement. It's not perfect in many respects, so I'm looking to improve the performance by reclocking the unit, in itself not a difficult task. What I'm asking, I guess, is actual reclocking of the SPDIF output at 2x the original freq of any benefit sonically, or is the use of a high quality clock in the unit enough of a benefit in itself. I will probably disable all the on board dac conversion circuitry as I will only use it as a transport unit. I just acquired a spare so I can experiment to my hearts content.
I hope I was coherent enough.
Best regards, Bill
Hi Ian,
I will try to address this as intelligently as I am able to. I have three different units I can use as a transport, but the old Philips CDM4/19 in the 502 pretty much much smokes them in the PRAT department with a simple pulse trafo output arrangement. It's not perfect in many respects, so I'm looking to improve the performance by reclocking the unit, in itself not a difficult task. What I'm asking, I guess, is actual reclocking of the SPDIF output at 2x the original freq of any benefit sonically, or is the use of a high quality clock in the unit enough of a benefit in itself. I will probably disable all the on board dac conversion circuitry as I will only use it as a transport unit. I just acquired a spare so I can experiment to my hearts content.
I hope I was coherent enough.
Best regards, Bill
I will try to address this as intelligently as I am able to. I have three different units I can use as a transport, but the old Philips CDM4/19 in the 502 pretty much much smokes them in the PRAT department with a simple pulse trafo output arrangement. It's not perfect in many respects, so I'm looking to improve the performance by reclocking the unit, in itself not a difficult task. What I'm asking, I guess, is actual reclocking of the SPDIF output at 2x the original freq of any benefit sonically, or is the use of a high quality clock in the unit enough of a benefit in itself. I will probably disable all the on board dac conversion circuitry as I will only use it as a transport unit. I just acquired a spare so I can experiment to my hearts content.
I hope I was coherent enough.
Best regards, Bill
Hi Bill, there is an interesting article on general SPDIF reclocking and TNT audio HERE.
I've no personal experience with SPDIF reclocking but, if you start with a 16Mhz clock with a /2 output (for the processor chip) you'd not loose anything if you ended up reclocking the SPDIF back to 8Mhz. I've yet to find an application where replacing the clock (including the transport and servo section) did not return massive improvments in quality.
Personally, I'd try it at 16Mhz 1st. As for any change to audio quality, you'd need to try the transport at each freq. Should be very easy to swap between the 2 freq once the work is done!
Also, does you're transport have the large loading cog on the right like many other 4/19 player (Marantz CD40,42,50,52 etc...) if so, you'll need to replace the wheel soon!!! Search 'CDM4 Gear' on ebay for a copy part! 😎
I've no personal experience with SPDIF reclocking but, if you start with a 16Mhz clock with a /2 output (for the processor chip) you'd not loose anything if you ended up reclocking the SPDIF back to 8Mhz. I've yet to find an application where replacing the clock (including the transport and servo section) did not return massive improvments in quality.
Personally, I'd try it at 16Mhz 1st. As for any change to audio quality, you'd need to try the transport at each freq. Should be very easy to swap between the 2 freq once the work is done!
Also, does you're transport have the large loading cog on the right like many other 4/19 player (Marantz CD40,42,50,52 etc...) if so, you'll need to replace the wheel soon!!! Search 'CDM4 Gear' on ebay for a copy part! 😎
Hi Ian,
I appreciate the advice, and I'll proceed just as you have outlined and see how much I can improve the output. I have a Tent XO2 that I will finish populating and find a couple cans to try 8 and 16mhz. The 8mhz cans are hard to find, probably have to get it from Guido. I imagine separate clock feeds to the various parts are beneficial.
The 500-502 units have the entire mechanism sled mounted, pretty cool looking when you open the drawer. I tried some basic dac mods in it a couple years ago, but 1543s just arent my cup of tea. Tried the DD stacked unit also, not for me.
I've been thinking about building the other unit up with I2S fed to an upsampling dac, skipping all the spdif conversions, but that's for another day.
Thanks again and best regards, Bill
I appreciate the advice, and I'll proceed just as you have outlined and see how much I can improve the output. I have a Tent XO2 that I will finish populating and find a couple cans to try 8 and 16mhz. The 8mhz cans are hard to find, probably have to get it from Guido. I imagine separate clock feeds to the various parts are beneficial.
The 500-502 units have the entire mechanism sled mounted, pretty cool looking when you open the drawer. I tried some basic dac mods in it a couple years ago, but 1543s just arent my cup of tea. Tried the DD stacked unit also, not for me.
I've been thinking about building the other unit up with I2S fed to an upsampling dac, skipping all the spdif conversions, but that's for another day.
Thanks again and best regards, Bill
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