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Valve DAC from Linear Audio volume 13
Valve DAC from Linear Audio volume 13
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Old 16th September 2020, 05:58 PM   #881
agent.5 is offline agent.5  United States
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The board is clock agnostic. It just needs two clock inputs via u.fl connectors. People can use any clocks that they want. I can do a separate clock board for NKD/Crystek. Any interest or preference?

Putting the entire clock input section into a separate pluggable module is interesting and I have been thinking about it as well. So, LVPECL, LVDS or CML clock format, instead of just TTL, can also be used.

Last edited by agent.5; 16th September 2020 at 06:14 PM.
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Old 16th September 2020, 06:19 PM   #882
nautibuoy is offline nautibuoy  United Kingdom
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Yes, I understand that the board is agnostic wrt clocks, I was just thinking that the option of pluggable oscillators would give more options and potentially make things simpler as a starting point but I respect that it's your decision on how you take it forward.

Last edited by nautibuoy; 16th September 2020 at 06:22 PM.
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Old 16th September 2020, 06:21 PM   #883
nautibuoy is offline nautibuoy  United Kingdom
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I posted the last of the bare PCB requirements today. Just need to get the smd soldering done so I can start shipping them out.

Still no sign of an import duty bill!
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Old 16th September 2020, 06:25 PM   #884
MarcelvdG is offline MarcelvdG  Netherlands
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Reply to post 879 of this thread: If I interpret the third plot from post #2604 of the thread you linked to correctly, there is a peak of -52.75 dBc at 3/2 times the desired clock frequency. I'm pretty sure that would be a disaster when the DSD512 signal comes from a straightforward single-bit sigma-delta modulator. I'd rather use oscillators at 22.5792 MHz and 24.576 MHz and get rid of the doubler.

Last edited by MarcelvdG; 16th September 2020 at 06:35 PM.
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Old 16th September 2020, 06:45 PM   #885
agent.5 is offline agent.5  United States
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Thanks Marvel. Will order just the regular 22/24 instead.
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Old 16th September 2020, 06:56 PM   #886
agent.5 is offline agent.5  United States
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Quote:
Originally Posted by nautibuoy View Post
Yes, I understand that the board is agnostic wrt clocks, I was just thinking that the option of pluggable oscillators would give more options and potentially make things simpler as a starting point but I respect that it's your decision on how you take it forward.
yes. I agreed. I will draft something, allowing clock options. Crystek has a new clock. Use this one?

https://www.crystek.com/crystal/spec...k/CCHD-957.pdf
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Old 17th September 2020, 06:21 AM   #887
agent.5 is offline agent.5  United States
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Did a bit of research and I think moving all the clock parts to a separate board is doable. How about plugging the oscillators onto the main board vertically, similar to how a GPU plugs into a PCIe slot? Illustrated on the first row, second column of the pdf. I have been looking for 100 ohm differential card edge connectors, and there are not many.

See

https://www.carlisleit.com/wp-conten...Connectors.pdf

Last edited by agent.5; 17th September 2020 at 06:23 AM.
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Old 17th September 2020, 03:30 PM   #888
nautibuoy is offline nautibuoy  United Kingdom
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I finally received an invoice from Fedex for the Import duty and tax for the main PCBs but fortunately it was a little less than my estimate so there is a small decrease in the cost of each board. At least now we have the final figures for the board costs and can start sorting out final payments - at least for everyone who's boards have already been sent.

I've attached an updated spreadsheet screengrab reflecting these costs. Looking at the 'Final Payment' column, if the cell for you is blue can you please send me a payment for the amount shown - this will close the transaction. If your cell is orange you are due a refund for an overpayment and I'll process these later this evening. If your cell has no colour no further payment/refund is due at this time.

When you make payments to me please use PayPal family and friends to avoid my incurring fees.

I'm still missing two delivery addresses for the subscriber names shown in orange.

I'm hoping to get the soldering underway next week.

Has anyone started to assemble their project yet?

Cheers

Ray
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Last edited by nautibuoy; 17th September 2020 at 03:32 PM.
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Old 17th September 2020, 04:53 PM   #889
MarcelvdG is offline MarcelvdG  Netherlands
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Quote:
Originally Posted by agent.5 View Post
I have been looking for 100 ohm differential card edge connectors, and there are not many.

See

https://www.carlisleit.com/wp-conten...Connectors.pdf
If the connector is electrically short (that is, if the signal can bounce back and forth in the connector a few times within the signal's rise or fall time), the characteristic impedance will not be very critical. What is the shortest rise or fall time of the clock signals? (I should know, but I have no access to the datasheets of your LVDS drivers at the moment.)
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Old 17th September 2020, 05:10 PM   #890
Mikky1975 is offline Mikky1975  Italy
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Ciao,
I’m wondering if I’m underestimating the effect of having the BBB inside the same chassis as the dac. I’m interested in your thoughts and projects because I was thinking about just doing a box-in-a-box for the bbb and then isolate/reclock. Do you think there should be audible benefits in a two-chassis implementation? Is it worth the extra care one must give to the clock/signal across more than a couple of centimeters?
I’m an IT guy, not an electronic engineer so be gentle, I’m just asking ��

Cheers,
Mirko
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