DAC AD1862: Almost THT, I2S input, NOS, R-2R

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#9,628
Hi,
Im back for a couple of questions. I hope you guys arent tired of me. 😛

1. I cant seem to find Audio grade 4.7uf caps for C15,C25. From what I've seen from previous posts. This means that I can use caps with values between 1uf-10uf
with a voltage rating of more than 25V for C15,C25.
But for C16,C26, the values have to be 10x of C15,C25.
ie C15,C25 = 2.2uf C16,C26 = 22uf
C15,C25 = 5uf C16,C26 = 50uf
C15,C25 = 10uf C16,C26 = 100uf (Maximum value)
Can I assume this?

miro1360 said:
This was information that I also tried to decipher for a long time. Use a type of capacitor that is suitable for audio, because the sound quality can depend on it 😊
C16 is definitely noise reduction capacitor for voltage reference. You can use from 10uF up to 100uF and you won't spoil anything (the datasheet shows that it is the RC filter).
Questionable is C15, because it reduces the output noise from the control portion of the DAC. I would probably put a higher value than 1uF here, but not more than 10uF (because we don't know how this filtration works).
Probably no one has figured out what is better 🤣 ... just don't give less than 1u+10u.
Click to expand...

2. Can I use film caps for these slots or is it overkill/unnecessary?
3. Can I mix the types of caps for these two slots? ie. Tantalums for C15,C25 and Electrolytics for C16,C26?
4. If the BOM refers to a 4.7uf/25v, is it safe to assume that I can use any 4.7uf caps with any voltage rating that is higher than 25v
5. Does anyone know if putting a higher capacitance in slots C15,C25 will yield a better sound? Any recommendations for this slot?
6. What wire gauges are you using? I looking to get silver plated wires from https://www.aliexpress.com/item/1005005944550167.html?spm=a2g0o.cart.0.0.202b38davhlwzo&mp=1

Thank you

PS. Just got my chips from @tamra
 

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#9,631
@d3stiny
I used Rubycon MuU series Pmlcap 4.7uf 35v
and Rubycon PZJ 47uf 63v polymer cap.
Don't know about value.
No problem to use higher voltage caps.
Personally,I don't like silver coated or silver　wire.
For signal wire, I use 0.1mm-0.2mm.
Only my preference.
 
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#9,632
Cauwil said:
@miro1360 : just as brijac did with his dual amp adapter : https://www.diyaudio.com/community/...st-tht-i2s-input-nos-r-2r.354078/post-7358627 - psu gnd, left gnd and right gnd are separated to prevent ground loops 😉 - since psu gnd is only needed for caps.
Click to expand...
It is not possible with TPA6120 I/V PCB because there is one common ground under the IC (heatpad is GND). You need to build two I/V PCBs for this purpose and use only one channel from each PCB. This I/V is very cheap, it should not be a financial problem 🙂
 
#9,633
@miro1360 : Thanks for your answer 😉 . My idea was to connect :
IR gnd, VR gnd and pin4 together,
IL gnd, VL gnd and pin17 together
without connecting them to the common ground. I will try to generate a gerber file...

BTW, I listened to this tpa6120 I/V module with Vishay s102k Riv - no R3/R4 output resistors, and it is one of the best opamp I have heard so far : very smooth, very natural, very detailed - no harshness, no sibilance - excellent, better than Bursons and co...
 
#9,634
@Cauwil Common ground for these signals is gnd from TPA6120. The GND under TPA6120 is very important, currents are returning here. If you cut it, it can be bad, note that this is high speed I/V.

Return path for audio signal is GND under signal path:

If you really want to "isolate channels", use 2x TPA6120 I/V, one for each channel ... that is the only way how to avoid oscillations - do not cut the GND in any way 😉

TPA6120 I/V sounds really great, and it is so cheap, cheaper than basic opamps. It sounds great especially when it is designed with these foil capacitors. I have used it as a reference for many years and I waited for someone who will share it ... but no one ... only me again :Pirate:
 
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#9,635
@d3stiny
1. yes you can use 1uF-10uF up to 10uF-100uF, just 1:10 ratio, use lowESR electrolyte nichicon panasonic or rubycon, avoid tantalum or polymer (it sounds bad ... even MLCC ceramic is better than this polymer)
2. film caps can be used, but it will be big, but you can 🤣 ... if you do it, the leg between DAC and capacitor is the shorter, another leg can be longer
3. you can mix, but avoid tantalum and polymer for audio
4. true
5. higher than 10-100uF is not recommended
6. shorter wires are recommended, don't go crazy with the material and use copper
 
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#9,637
miro1360 said:
@d3stiny
1. yes you can use 1uF-10uF up to 10uF-100uF, just 1:10 ratio, use lowESR electrolyte nichicon panasonic or rubycon, avoid tantalum or polymer (it sounds bad ... even MLCC ceramic is better than this polymer)
2. film caps can be used, but it will be big, but you can 🤣 ... if you do it, the leg between DAC and capacitor is the shorter, another leg can be longer
3. you can mix, but avoid tantalum and polymer for audio
4. true
5. higher than 10-100uF is not recommended
6. shorter wires are recommended, don't go crazy with the material and use copper
Click to expand...

tamra said:
@d3stiny
I used Rubycon MuU series Pmlcap 4.7uf 35v
and Rubycon PZJ 47uf 63v polymer cap.
Don't know about value.
No problem to use higher voltage caps.
Personally,I don't like silver coated or silver　wire.
For signal wire, I use 0.1mm-0.2mm.
Only my preference.
Click to expand...
Thank you for both of your clarification.
 
#9,640
Cauwil said:
@miro1360 : just as brijac did with his dual amp adapter : https://www.diyaudio.com/community/...st-tht-i2s-input-nos-r-2r.354078/post-7358627 - psu gnd, left gnd and right gnd are separated to prevent ground loops 😉 - since psu gnd is only needed for caps.
Click to expand...

I've not split gnd there (gnd plane exists on the adapter itself yes, but i wouldn't call it split). What i did was allow direct gnd connection from it to the gnd below on the dac board, if high speed opamp was used, because with adapter you increase supply trace length to the dac board (and local decoupling caps there). Split gnd is the last option in some cases, and gnd in mixed signal circuits should be connected (but guided, which is the most important part) at one spot. Rule of thumb is analog>digital flow.

I don't mind tantalums, actually i prefer them, but has to be high grade, and specs for the job (that gets expensive). Poscaps are amazing for digital, better than lytics. Lower leakage ones for analog decoupling (T489 as one of the good ones, fairly low esr but way less leakage than poscaps). But as with everything, it's not that simple as it also depends on the power supply implemented, and regulator choice, as well as tech of the chip being decoupled. And of course, never use tantalum as a cap in signal path 😅 We have way too much film cap choises today to use both lytics and tants in such a position.
 
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