I just don't get it. I am not trying to be critical as I know this seems very popular by the number of designs and products, but why would one go through the trouble of a DAC with .000-something distortion to add a tube buffer and generate massive distortion? If you just want huge even harmonics, just unbalance a differential LTP. I mean tubes have their place as part of the artist and producer making the original sound. But why are we trying to distort that? Sure, an over-driven Fender amp, Tube mic for vocals, but a DAC?
I have listened to tube equipment, from old Dyna to Cary, LoLita, and Manley. I just don't get it.
I have listened to tube equipment, from old Dyna to Cary, LoLita, and Manley. I just don't get it.
I couldn't agree with you more, that's one of the reasons why I chose a different approach. See sections 1 and 2 of https://linearaudio.net/sites/linearaudio.net/files/03 Didden LA V13 mvdg.pdf
In order to get sound, DSD_ON must be high and MUTE must be low. If both DSD_ON and MUTE had the reverse polarity, you could just swap them, but now you will need an AND gate. Two diodes and a resistor could do the trick.
Hey Ray - couple questions maybe you know the answer. Is Digi-Key smart enough that if I order from your cart in the UK to ship to the US from the US distributor? I'd hate to ship across the pond...or should I just rebuild using the US site?
looking at the through hole components there are a couple duplicate line item warnings (and one obsolete; BC558BTACT-ND should be BC559BTACT-ND is recommended as a direct sub).
Sorry I haven't dug into the BOM documents to verify...if its easy for you to check below are items sh
BC4062CT-ND
MRS25000C2202FCT00
Vishay Beyschlag/Draloric/BC Components
RES 22K OHM 0.6W 1% AXIAL
is shown twice (qty4) for a total quantity of 8
BC4056CT-ND
MRS25000C2200FC100
Vishay Beyschlag/Draloric/BC Components
RES 220 OHM 0.6W 1% AXIAL
is shown twice (qty1) for a total quantity of 2
maybe there is a different cart?! I thought it was a recent post and now I've read like 10 pages and can't find what I clicked on, haha!
looking at the through hole components there are a couple duplicate line item warnings (and one obsolete; BC558BTACT-ND should be BC559BTACT-ND is recommended as a direct sub).
Sorry I haven't dug into the BOM documents to verify...if its easy for you to check below are items sh
BC4062CT-ND
MRS25000C2202FCT00
Vishay Beyschlag/Draloric/BC Components
RES 22K OHM 0.6W 1% AXIAL
is shown twice (qty4) for a total quantity of 8
BC4056CT-ND
MRS25000C2200FC100
Vishay Beyschlag/Draloric/BC Components
RES 220 OHM 0.6W 1% AXIAL
is shown twice (qty1) for a total quantity of 2
maybe there is a different cart?! I thought it was a recent post and now I've read like 10 pages and can't find what I clicked on, haha!
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I am working on converting this project to Mouser US.
Ray, A72QK2100ZA00M is only available bulk - 5000. I found 2 axial substitutes, that are with higher voltage rating:
942C20S1K-F
940C30S1K-F
Would you be so kind to give us a hand here?
Other than that, I think all parts are matched with only a few hiccups, but those are easy to resolve.
Whoever is interested, please PM me to share the project with you.
luchoh,
Digikey in the US seems to have them in single quantity: https://www.digikey.com/en/products/detail/kemet/A72QK2100ZA00M/5141832
Digikey in the US seems to have them in single quantity: https://www.digikey.com/en/products/detail/kemet/A72QK2100ZA00M/5141832
Thank you!
The board is from JLsounds - from them came another good suggestion of using an optocoupler TLP185 (see schematic).
The DSDon and Work/Mute signal is provided on the JLsound I2S board on the USB side which is galvanically isolated from the I2S side. So using the optocoupler would maintain this isolation.
Marcel - is the isolation worth it with the valve DAC or not, what do you think?
Yes, they reversed the "problem" in ver.III - now DSD_on is signalled by "low":
18 DSD_PCM_iso Output
Audio Stream Format isolated
Low: the digital audio output stream format is DSD
High: the digital audio output stream format is PCM
20 MUTE_iso Output
Mute signal isolated
Low: the audio data stream is valid
High: the audio data stream is not valid and the DAC
must be muted.
One can still catch the high DSD flag on the unisolated side:
8 DSD_PCM Output
Audio Stream Format
Low: the digital audio output stream format is PCM
High: the digital audio output stream format is DSD
Just goes to show that there is no real logic to logic, doesn't it?
---
I have a ver.II board, though.
18 DSD_PCM_iso Output
Audio Stream Format isolated
Low: the digital audio output stream format is DSD
High: the digital audio output stream format is PCM
20 MUTE_iso Output
Mute signal isolated
Low: the audio data stream is valid
High: the audio data stream is not valid and the DAC
must be muted.
One can still catch the high DSD flag on the unisolated side:
8 DSD_PCM Output
Audio Stream Format
Low: the digital audio output stream format is PCM
High: the digital audio output stream format is DSD
Just goes to show that there is no real logic to logic, doesn't it?
---
I have a ver.II board, though.
It could help to keep interference from entering the DAC and optocouplers are not expensive, so adding two optocouplers to maintain the isolation seems to be a sensible approach.
Apologies that I've been absent for a few days - we've had a serious fault on our phone line to the house so I've been mostly offline. I'll catch up with what's going on and try to respond to some questions I've received today. In the meantime, the group buy for the DSD version boards is complete with all payments made and all boards delivered.
Attachments
When I order from Digikey the order is shipped from the US. I'm sure if you pick up the BOM I set up it'll be translated to the US Digikey site as the part numbers will be the same. I'll have a look at the specific items as I may well have made a mistake or two.
Ray