this looks interesting, some were using AD844 open loop for IV but this chip is so expensive, OPA861 is much more affordable for experimenting with.
After some back and forth I do think the input resistor (200r) does slightly improve dynamics, but even though its pretty benign there is slight distortion, and both basically have same character of the OPA1612. The trafo sounds good cos its a truly passive solution I guess.
Also I forgot that the the feedback caps were also removed when adding the input resistor, like a typical inverting amp. this could be effecting the sound too.
The frustrating part is that the trafo itself is probably adding more distortion than what is generated by the voltage on the DAC output, I would like to try high value IV resistor without any active stage or trafo but worried about damaging the DAC.
Also I forgot that the the feedback caps were also removed when adding the input resistor, like a typical inverting amp. this could be effecting the sound too.
The frustrating part is that the trafo itself is probably adding more distortion than what is generated by the voltage on the DAC output, I would like to try high value IV resistor without any active stage or trafo but worried about damaging the DAC.
you perhaps can swap the MOX by a bulk or a cool axial wirewound Vishay, the last costs nothing. or maybe if you have a 5W Mills as well ?
I have one to taste and a tons of wirewound fro Vishay but finally was happy enough with the Rohpoint and the LCR tin foil styren here. Though I really ask myself about the bulk Vishay Powertron : theorically should be better than the low wattage wirewound... but mine is good enough. You found better the RN65 than the noiser Allen B. that has some "tonal" quality ?
Edit : in the post above I talked for the serie he uses with opa to swap the MOX if I understood correctly what was said (no i/v purpose)
Edit : in the post above I talked for the serie he uses with opa to swap the MOX if I understood correctly what was said (no i/v purpose)
Last edited:
I received my AD1862 chips yesterday 😀
Hopefully by the weekend I can power up to verify all works as it should.
Maybe hold off ordering your pcb’s until then, just in case there is an unforeseen issue.
Hopefully by the weekend I can power up to verify all works as it should.
Maybe hold off ordering your pcb’s until then, just in case there is an unforeseen issue.
Awesome progress! I am very curious about the result.
I hope it will play the music on the first try 😀
I hope it will play the music on the first try 😀
Good news Miro and All!
DAC board powered up without any drama. Psu’s are trimmed to feed +/-12vdc and +/-5vdc.
DC offset 1mV with OPA134pa installed
DC offset 30mV with Burson discrete opamps installed
I will feed an I2S signal tomorrow and check for first sound.
Fingers crossed 😉
DAC board powered up without any drama. Psu’s are trimmed to feed +/-12vdc and +/-5vdc.
DC offset 1mV with OPA134pa installed
DC offset 30mV with Burson discrete opamps installed
I will feed an I2S signal tomorrow and check for first sound.
Fingers crossed 😉
Attachments
Hello Miro,
i want to try your dac, never heard ad1862. I have tda1541, pcm1702, pcm1704.. and some sigma delta akms dacs that have been testing for about 2 years
dacs i own/heard:
tda 1541a, valve output / diamond buffer
pcm 1702 classic opamp iv
pcm 1704 opa 861 iv
ad 1865 audio note clone valve output
tda 1543 passive iv
soekris dam
sigma deltas:
ak4396 valve output
ak4495 opamp or output trafo
ak4493 opamp or output trafo (several boards)
ak4497 opamp or output trafo
cirrus 4397 opamp or output trafo.
i like the most pcm1702 and tda1541a.
are your files correct?? just send to jlpcb to print???
Best regards
Nuno
Last edited:
this ebay board, but is heavy modified.
PCM1702 decode board finished | eBay
using jlsounds i2soverusb direct on the pcm1702 chips.
only using first i/v opamp.
changed all caps even the rectifier diodes
here the link how it sounds:
YouTube
YouTube
Last edited:
good news Vunce, so far it looks promising.
OPA134PA will sound good 🙂 ... test others as well (LM6171, ADA4898-1, LME49990 (hard to find), AD844, ...)
OPA134PA will sound good 🙂 ... test others as well (LM6171, ADA4898-1, LME49990 (hard to find), AD844, ...)
It should be correct, Vunce is testing if it sounds with I2S connected, so wait a bit.
Otherwise in the post #81 is the final PCB.
@Pistolerro,
have you not a lisbona 's friend that own an aya dac as well ? Your id is telling me something but didn't remember where ??
Anyway, if the chips are good, the design, the powersupply, you will not be disapointed by the sound of it and it will swap the pcm 1702 in your short list with the tda1541 side to side, this last is harder to work with to extract the best.
that's a very good list of dac chips you have, the Cirrus is a collector and disearve if Ebay kitchen dac you make pcbs for them .
Could you please rate your dac devices list in order of liking for us please as you have a pretty collection ? What tube used for the tda 1541 ?
have you not a lisbona 's friend that own an aya dac as well ? Your id is telling me something but didn't remember where ??
Anyway, if the chips are good, the design, the powersupply, you will not be disapointed by the sound of it and it will swap the pcm 1702 in your short list with the tda1541 side to side, this last is harder to work with to extract the best.
that's a very good list of dac chips you have, the Cirrus is a collector and disearve if Ebay kitchen dac you make pcbs for them .
Could you please rate your dac devices list in order of liking for us please as you have a pretty collection ? What tube used for the tda 1541 ?
Last edited:
@ Vunce,
Coooool ! The TSA ldo is singing diferently according the main caps of th power supply before him and it can be a great way to improve or tune to your liking the tonal of the sound 🙂. I like this ldo better than some lower noise chips even for the I2S front end!
Btw the little blue caps of the main PS board are Philips MKT (very spcial those ones) or Cornel Dublier or something else ?
Damned my chips were sent from China but without tracking number, fingers crossed !
Coooool ! The TSA ldo is singing diferently according the main caps of th power supply before him and it can be a great way to improve or tune to your liking the tonal of the sound 🙂. I like this ldo better than some lower noise chips even for the I2S front end!
Btw the little blue caps of the main PS board are Philips MKT (very spcial those ones) or Cornel Dublier or something else ?
Damned my chips were sent from China but without tracking number, fingers crossed !
Good eyes Diyiggy!!
The main power supply is based on LM317/337 regulators with a CRC/reg/CLC configuration for the +/-12vdc. The unregulated output feeds the TPS LDO for the +/-5vdc supply.
I’ve got another very compact psu solution I’m working on, waiting for the parts to arrive though.
Cheers!
The main power supply is based on LM317/337 regulators with a CRC/reg/CLC configuration for the +/-12vdc. The unregulated output feeds the TPS LDO for the +/-5vdc supply.
I’ve got another very compact psu solution I’m working on, waiting for the parts to arrive though.
Cheers!