hello folks
have spent the last couple of weeks A/B testing my all out choke input Buffalo III/Legato dac against my new 4 boards std psu DDDAC1974, which by the way needed a couple of weeks power-on to loosen up
The BIII has exaU21 usb to I2s converter with separate 5v psu besides also getting 3,3vdc from BIII board
both dc voltages to Legato and the dac board are fed from separate 250va transformers through MUR860 rectifiers , choke fed Placid HD shunt regs...the regs reg from 13,5 to 5,8 and 23 to 14,6 respectivelys(regs sounds better when plenty to regulate on)
have the two very different dac´s connected to two separate inputs and just change between exa and wave Io driver in foobar
very easy to compare
first verdict
BIII smoother and more dynamic and powerful
BUT the NOS has something going on that I like (which I also experienced with other dac builds) despite that it at first sounded pretty anemic and cold with less harmonics
my first thought was to increase transformer va and I took what I had at hand
250va for the dac psu and 80 va for the usb psu and the dynamics and basscontrol improved slightly, but less than expected
obviously something acted as a dynamic brake in the psu(I thought)
I then bypassed R1, R2 and the fuse and the impact was dramatic and suddenly the dac was up in league with my BIII in terms of basscontrol and dynamics
however I still perceived it a little harsh and cold in the top end which didn´t figure
(I use SE out and NO CAPS to S&B TVC)
I then tried replacing C7 and C8 with one Panasonic FC 1.000µF/35 and most of the "harshness" was gone....hmmmmmm tried removing the C9 and suddenly the whole dac sounded dull....back in with it and that´s the present status
next on schedule, while waiting for new transformers and chokes do be upstream of std psu´s is testing alternate usb to I2S converter to try and peg what differences between the two dac come from source, dac technology and psu differences
however my main conclusion so far is that I like the 1794s potential and will concentrate on further lifting it past my present reference.
I presently suspect the main source of my attention will first be on the psu options and I also intend to try replacing DD supplies with Buffalo shunt supplies in same config as my BIII
then Sowther.......
best
Leif
have spent the last couple of weeks A/B testing my all out choke input Buffalo III/Legato dac against my new 4 boards std psu DDDAC1974, which by the way needed a couple of weeks power-on to loosen up
The BIII has exaU21 usb to I2s converter with separate 5v psu besides also getting 3,3vdc from BIII board
both dc voltages to Legato and the dac board are fed from separate 250va transformers through MUR860 rectifiers , choke fed Placid HD shunt regs...the regs reg from 13,5 to 5,8 and 23 to 14,6 respectivelys(regs sounds better when plenty to regulate on)
have the two very different dac´s connected to two separate inputs and just change between exa and wave Io driver in foobar
very easy to compare
first verdict
BIII smoother and more dynamic and powerful
BUT the NOS has something going on that I like (which I also experienced with other dac builds) despite that it at first sounded pretty anemic and cold with less harmonics
my first thought was to increase transformer va and I took what I had at hand
250va for the dac psu and 80 va for the usb psu and the dynamics and basscontrol improved slightly, but less than expected
obviously something acted as a dynamic brake in the psu(I thought)
I then bypassed R1, R2 and the fuse and the impact was dramatic and suddenly the dac was up in league with my BIII in terms of basscontrol and dynamics
however I still perceived it a little harsh and cold in the top end which didn´t figure
(I use SE out and NO CAPS to S&B TVC)
I then tried replacing C7 and C8 with one Panasonic FC 1.000µF/35 and most of the "harshness" was gone....hmmmmmm tried removing the C9 and suddenly the whole dac sounded dull....back in with it and that´s the present status
next on schedule, while waiting for new transformers and chokes do be upstream of std psu´s is testing alternate usb to I2S converter to try and peg what differences between the two dac come from source, dac technology and psu differences
however my main conclusion so far is that I like the 1794s potential and will concentrate on further lifting it past my present reference.
I presently suspect the main source of my attention will first be on the psu options and I also intend to try replacing DD supplies with Buffalo shunt supplies in same config as my BIII
then Sowther.......
best
Leif
Dear Leif,
That's a nice explanation, thank you for sharing your experience.
I have similar experiences. The overall dac design is very nice, the power supply is definetely the place where a lot of gain can be made.
Good to see this dac is better than the buffalo, I do not own a buffalo dac but always wondered what I was missing.
That's a nice explanation, thank you for sharing your experience.
I have similar experiences. The overall dac design is very nice, the power supply is definetely the place where a lot of gain can be made.
Good to see this dac is better than the buffalo, I do not own a buffalo dac but always wondered what I was missing.
Hi,
So today I soldered in the new blue board with Tent shunt regs.
I also added single ended capacitor output (parallel to the direct balanced output that I use on my amps) so I can use the dac during the next listening session at Klaus his Goto system.
The S/P diff is not connected yet, I also need to modify my cd player for sp-diff out.
The Salas shunt reg also needed some modification because the current draw is higher. The dac runs at 1,16amps now, this is the limit for the Salas reg.
On the pictures you can also see the Raspberry Pi and Alix that I use for streaming. I2S out on the Pi is something I will connect later on.
I will refrain from noting listening results, first the board needs some time to run in. First impressions however are very good, better than the old board without shunts? Yes I think so
Regards,
Are your dac boards needs more current?
I would think more then 200mA for 1 dacboard?
I can't place the big red cap nearby the motherboard and reg shunt board?
I'm interested in your findings (SQ).
Hi,
Shunt's draw more current than the standard regulators, around 200mA for one board.
The red cap on the motherboard is a black gate non polar and sits in front of the shunt regulators. Behind the shunts I left out the capacitors as they slow down the response of the shunt.
The shunt current ratings are:
5v 40mA
3,3v 35mA
3,3v 50mA for tent clock
I will report my findings after running in.
Regards,
Last edited:
PUBLIC APPRECIATION
just wanted to say thanks to Doede, I have been tinkering around with HIFI for years but this is my first DIY build, I have had a couple of problems along the way, Doede has gone way out of his way to help.
I now have a two board DAC with shunt regs sounding superb, it is way better than I expected.
Many Thanks!
just wanted to say thanks to Doede, I have been tinkering around with HIFI for years but this is my first DIY build, I have had a couple of problems along the way, Doede has gone way out of his way to help.
I now have a two board DAC with shunt regs sounding superb, it is way better than I expected.
Many Thanks!
Last edited:
Thanks for the info
I'm very curious about the Tent Labs shunt regs and their influence on the SQ ,especially the regs on the motherboard.
Hi,
Your setup looks awesome! I see you use a different ps board than Doede's ones. Would you please give us a rundown on your tweak other than the Shunt regulators? I see the big red cap as replacement for 470uf and also next to it the 74uf is missing? Am so keen to have the Shunt regulator upgrade but given the price for each 4 shunts exceed the price for each addition DAC board, hopefully the effort worth doing?
Best,
I use the Salas shunt board, these are obtained with a group buy on this forum, just search for salas.
The biggest sound improvement is with the shunts on the dac boards, the motherboard has less to gain with the shunts but still improves.
I made a typo in my previous post: one dac board takes around 250mA of current.
When you would want to shunt regulate an 8 dac stack the shunts will be quite costly but I had an idea for this:
Just take off all regulators from the dac boards and make two separate Salas shunt regulators and feed it directly to the dac boards. One for analog and one for digital stages. You can than use the digital salas to also feed the motherboard. This can pretty easily be done by not soldering the power supply wire from the motherboard to the dacs, if you leave a cap position open near all dac chip feed points, than you can use that hole to feed a power supply wire from top to bottom dac board. Connect them from top to a Salas and you are in business!
As local decoupling just use some small and fast wima capacitors, you can leave out the bank of electrolythics. This will bring you a very speedy and responsive power supply.
The Salas regulates with kelvin sensing wires so the voltage will be regulated directly at the dac boards.
Another advantage of this appoach is that you can keep the digital and analog power supplies separated.
I havent tried this myself but I believe this would be a very nice improvement.
Anyone dare to try this?
The biggest sound improvement is with the shunts on the dac boards, the motherboard has less to gain with the shunts but still improves.
I made a typo in my previous post: one dac board takes around 250mA of current.
When you would want to shunt regulate an 8 dac stack the shunts will be quite costly but I had an idea for this:
Just take off all regulators from the dac boards and make two separate Salas shunt regulators and feed it directly to the dac boards. One for analog and one for digital stages. You can than use the digital salas to also feed the motherboard. This can pretty easily be done by not soldering the power supply wire from the motherboard to the dacs, if you leave a cap position open near all dac chip feed points, than you can use that hole to feed a power supply wire from top to bottom dac board. Connect them from top to a Salas and you are in business!
As local decoupling just use some small and fast wima capacitors, you can leave out the bank of electrolythics. This will bring you a very speedy and responsive power supply.
The Salas regulates with kelvin sensing wires so the voltage will be regulated directly at the dac boards.
Another advantage of this appoach is that you can keep the digital and analog power supplies separated.
I havent tried this myself but I believe this would be a very nice improvement.
Anyone dare to try this?
I was looking into the Placid HD boards. I believe Russ said in his thread on the Placid, that they would do in upwards of 2-3 amp, requiring increased heat sinking, and upgrading a few parts.
I am considering mounting the Placid boards vertically and using the case for the heat sink. Something like a 200-250 VA transformer for the DAC, and 100-150 for the Wave IO board.
Since you would only need one twisted pair for the PSU boards, whether I could use only one transformer with 2 pairs, one to each, assuming I can use the same voltage for the 12VDC and 5VDC outputs. They are very configurable as I understand it.
I am considering mounting the Placid boards vertically and using the case for the heat sink. Something like a 200-250 VA transformer for the DAC, and 100-150 for the Wave IO board.
Since you would only need one twisted pair for the PSU boards, whether I could use only one transformer with 2 pairs, one to each, assuming I can use the same voltage for the 12VDC and 5VDC outputs. They are very configurable as I understand it.
I would think the placid would also work, I haven't tried it though. I find the Salas highly configurable, it has room to use different types of rectifiers and caps, can be used for low and high voltages, 2,5 to 45v depending if you use BJT or Mos fet output.
You might need more than just the case as a heatsink if are doing 1-3amp supplies but are shunting a significant amount of that (i.e., when all the dac boards are idle or if you build-in a big current overhead).