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Valve DAC from Linear Audio volume 13
Valve DAC from Linear Audio volume 13
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Old Yesterday, 06:58 PM   #901
agent.5 is online now agent.5  United States
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I like more inputs regarding connectors, please.

Gold plated? Audiophile approved? No, not those concerns. I am talking about what can others solder? I assume that most do not have access to reflow oven, I certainly do not. I have a hot plate and I can probably solder the Carlisleit connector. See the illustration of the vertical mount on page 2 here

https://www.carlisleit.com/wp-conten...0-XX_REV_F.pdf

The tiny pins are underneath the housing. There is no room for a soldering iron to access. Even hot air may not reach.

Based upon Marcel's calculation that if the distance is less than 1.75cm, impedance may not be critical. I am also looking at PCIE-x1 connectors with through holes (easiest to solder),

https://cdn.amphenol-icc.com/media/w...g/10146514.pdf

or something with the pins rotating outward, allowing a soldering iron tip or hot air to get to it. See

https://www.molex.com/pdm_docs/sd/1733000106_sd.pdf

What do you guys think?
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Old Yesterday, 08:04 PM   #902
nautibuoy is online now nautibuoy  United Kingdom
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Quote:
Originally Posted by Mikky1975 View Post
I didn’t know it was so easy nowadays, thanks!
Its easy enough to get the PCBs made but just be aware that ppy's reclocker has some pretty small smd soldering required.
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Old Yesterday, 08:46 PM   #903
nautibuoy is online now nautibuoy  United Kingdom
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Quote:
Originally Posted by agent.5 View Post
I like more inputs regarding connectors, please.
I'm interested in your design for two reasons;
  1. To see if the separate isolation tricks make a difference
  2. because it permits experimentation with different oscillator solutions (ppy's reclocker only accommodates the tiny NKD ones)

I'm fortunate in having access to oven facilities so I'll go with the flow (excuse the pun).

Have you considered running a GB for pre-assembled boards?
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Old Yesterday, 09:21 PM   #904
agent.5 is online now agent.5  United States
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I need to test the boards first and make sure they work. I am sure a group-buy can be arranged later.

Additional reasons to do all these are:

[1] the clocks are connected directly to the DAC, yielding the lowest possible jitter. Sending clock signals to PPY and then sending them back to the DAC is unnecessarily. We do not need to reclock at all, as Valve Dac already has reclocking circuit built-in.
[2] Using clocks that are 1/2 the frequency as PPY and still getting DSD512 output. From my reading, lower frequency oscillators have better characteristics than higher frequency ones.
[3] Power supply isolation. PPY uses power from BBB to power everything else. Here, we literally have a separate ccs-fed shunt regulator for each segment of the circuit.

I am less concerned about how long ethernet cables are used and how far to separate the BBB side from the Dac side. But, I suppose somebody can order a bunch of different length cables and experiment. These cables are no doubt the cheapest, best quality S/FTP cables that one can find.

And putting the clock input section onto a mezzaine board does provide infinite options for clock-rolling. I will provide a Ki-cad template as well, so you guys can easily experiment different clocks. How about putting differential drivers onto external oscillators and feed Valve DAC with differential signals? See posts 2696 - 2707


The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator

Last edited by agent.5; Yesterday at 09:45 PM.
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Old Today, 08:23 AM   #905
nautibuoy is online now nautibuoy  United Kingdom
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Quote:
I am sure a group-buy can be arranged later
Sounds good, I'm sure that'll be helpful to some people.

Quote:
[1] the clocks are connected directly to the DAC, yielding the lowest possible jitter. Sending clock signals to PPY and then sending them back to the DAC is unnecessarily. We do not need to reclock at all, as Valve Dac already has reclocking circuit built-in.
IIRC ppy's reclocker outputs MCK direct to the header, ergo, direct to the DAC? I don't send clocks to the ppy board because the oscillators are on the ppy board, though it is limited by the oscillators that can be used because of the PCB pads available. from ppy's board clock signals are fed back to the BBB via isolators.

Quote:
[2] Using clocks that are 1/2 the frequency as PPY and still getting DSD512 output. From my reading, lower frequency oscillators have better characteristics than higher frequency ones.
Yes, this will be interesting. I have another DAC (Buffalo 3SE) with an AckoSO3 isolator/reclocker - interestingly, I perceived the sound to be very slightly better with 90MHz oscillators (divided by 4) compared with 45MHz (divided by 2) - same family NKD oscillators.

Quote:
[3] Power supply isolation. PPY uses power from BBB to power everything else. Here, we literally have a separate ccs-fed shunt regulator for each segment of the circuit.
My implementation of ppy's reclocker has separate power supplies for each section; powering it from the BBB is just an option - you just omit the relevant components and provide a 5V supply to the header provided on ppy's PCB. Choice of power supply type is down to your preference.

Ray
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Old Today, 10:11 AM   #906
nautibuoy is online now nautibuoy  United Kingdom
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I made a mistake positioning the holes in the top panel of the chassis, (where the valves show through), on my build and, whilst it was only a 2-3mm, it was annoying me so I decided to remedy the situation. Instead of trying to botch it I did the job properly (if expensively) and ordered a completely new top panel from Schaeffer and chose to have it machined from blue anodised sheet - I think it looks rather nice.

Click the image to open in full size.

Click the image to open in full size.

Just having a listen now at my workdesk - I can't hear any difference but I am happier with it now.

Last edited by nautibuoy; Today at 10:14 AM.
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Old Today, 01:34 PM   #907
agent.5 is online now agent.5  United States
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Quote:
Originally Posted by nautibuoy View Post


IIRC ppy's reclocker outputs MCK direct to the header, ergo, direct to the DAC? I don't send clocks to the ppy board because the oscillators are on the ppy board, though it is limited by the oscillators that can be used because of the PCB pads available. from ppy's board clock signals are fed back to the BBB via isolators.
I think I should clarify what I wrote a bit more. PPY has clocks on board. They are X1 and X2 on the schematic

https://puredsd.ru/BBBreclk.pdf

Their signals go to U7, which is used to select one of two frequencies, and the selection is sent sequentially to the three U8s. I have clocks and selector U7 as well.


U8 is the so-called fifo reclocking that also is used on Ian's fifo/clock and Cronus/Hermes.

So, you ask everyone else is doing it, why not here?


Well, we already are. See schematic

https://www.diyaudio.com/forums/atta...dsdversion-pdf


Incoming data signals firstly go to U6A and U6B on page 3 of the schematic. They are the same type of ICs used on the fifo reclocking circuit. Valve Dac already has built-in reclocking. Consequently, there is no reason to double reclock and inherit extra jitter.

So, when I wrote it connects directly to the Dac, I meant the clocks go from a selector and then to the Dac, without going through extra, unnecessary steps.

Technically, we are sending a master clock to the Valve Dac, and slaving BBB to this clock. PPY and others do not do that.

Last edited by agent.5; Today at 02:02 PM.
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