Hi everyone,
I’m a reader of this topic for a long time because I’m going to purchase a dam1021 myself soon. For this the last half year build a powersupply specifically for the Soekris DAC.
It’s the sjöström SSR-03 superregulator board which should give me +9V, gnd and -9V
It, however doesn’t give me exactly matching voltages. I measure +9,09V and -9,21V
I remember reading that the Soekris board uses the two rails for the DAC and the analog section, so does that mean I’m ok with a slightly different voltage on both rails (120mV if I’m right)?
Or should it match exactly because I need symmetrical power?
Thanks a lot for any thoughts or answers.
Regards Maikel
I’m a reader of this topic for a long time because I’m going to purchase a dam1021 myself soon. For this the last half year build a powersupply specifically for the Soekris DAC.
It’s the sjöström SSR-03 superregulator board which should give me +9V, gnd and -9V
It, however doesn’t give me exactly matching voltages. I measure +9,09V and -9,21V
I remember reading that the Soekris board uses the two rails for the DAC and the analog section, so does that mean I’m ok with a slightly different voltage on both rails (120mV if I’m right)?
Or should it match exactly because I need symmetrical power?
Thanks a lot for any thoughts or answers.
Regards Maikel
It's OK for the rails to have slightly different voltages. You'll be fine.
There is an isolated versin of the serial. RTFM
I actually already did this (though the manual is not really extensive on this topic). That is why I was asking advice on a good TTL level RS232 USB convertor earlier in this thread. Yesterday I ordered the one I mentioned in my post, let's hope it will work ok...
Fedde
I am also exploring this route and I can confirm that it can be used. The setup I tested so far is:
Amanero I2S -> McFIFO/McDualXO -> DAM1021.
I can't say anything about sound quality at this point as I only just completed the implementation. If you want to explore this route make sure you get the 4x or 9x Mhz clocks as opposed to the 2x Mhz clocks if you need to play DSD.
Ultimately if Soren can provide an option for the DAM1121 to use external fixed clock then this approach could drive the DAC using the clocks on the McDualXO.
I am thinking about adding a reclocker / fifo to the I2S source of my DAM 1021-12 V4.
Can you comment on how much improvement / difference in sound quality do you hear with / without the McFIFO/McDualXO between the DAM and the Amanero I2S source ?.
Thanks.
It's very difficult to do a direct comparison as you can imagine. I'd say the difference is not very dramatic - presumably because the DAM is still internally-clocked so there is only so much an external reclocker can do.
I'm awaiting Soren to add a feature to the firmware to allow the DAM1121 to bypass the internal oscillator and use external clocking completely.
In the meantime I bought the USB RS232 TTL convertor mentioned above. It works perfectly at a very low cost. I could use the 5V power for the isolators on the Soekris PCB without problem (still within specification of IC). And the cable already comes with connectors you can put on the DAC pin headers, so I just needed to plug it in!
Fedde
I just recently modified my 2 Soekris DAM1021 Rev1 DAC setups and thought others might be interested.
The recent mods are to replace all of the on-board regulators with upgrade units... starting with replacing the FPGA 1.2V regulator with an ldovr.com LT3045-based board and the FPGA/clock/other digital circuits 3.3V with the ldovr.com dual LT3045 board for a full 1A capacity. Each of these rails would now be fed from a separate power supply... overkill, but I'm into serious overkill!
In preparation for the mods around the processing side of the board I restructured some of my original implementation details such as my isolated and non-isolated serial port connections and the connector for the volume control pot (which I re-configured to make it the same as on the Twisted Pear Buffalo-IIIPro board, as I use the same cases/bases for them and didn't want to damage a DAC board if I swapped it into a case/base previously occupied by the other and didn't remember to swap the VC connector leads).
Back to the regulator mods, I took a great deal of care to keep the regulators close to the original feed points and the connections short. The ldovr.com boards made this work well and were a good alternative to the OPC dual 4||LT3042 boards (sadly no longer available) I had originally planned to use for these positions, as those would have required much longer leads.
Several mods back I'd removed the output stages when I started using the RAW output and in concert with the digital-focused regulator upgrades I also would be replacing the shift register regulators and feeding them from two more separate power supplies, so I repurposed the existing filtering cap array by totally removing the negative rail array (making room for the 1.2V replacement regulator) and installing 3900uF/16V caps in the place of the positive rail caps (these were through-hole caps, I used them by insulating their bases with Kapton tape and bending the leads outward to mimic the SMD cap lead arrangement). I used the 3 caps nearest the power feed for the 3.3V rail and by removing the small filter resistor between that bank and the final cap that originally was mainly used for feeding the positive rail of the output stage, used that final cap for the 1.2V rail. ALSO by retaining the power feeds into the original cap bank, it preserved the original mute functionality and made this set of mods much easier to plan and implement.
For the +-5V shift-register rails, I used a +- pair of Sparkos Labs regulators. Here, like above, I wanted to keep the regulators as close to the fed circuits as possible, so I mounted them on the output end of the board, re-using the space where the output stages had been. Then I fed the power and grounds from the regulators outputs directly to the reference voltage stages using carefully-installed 28 gauge insulated wire. These regs got 47uF Black Gate NXs on their outputs and mid-sized filter caps on their inputs.
I'd also done the VRef mods needed for my Rev1 boards a couple of years ago. Just like these mods, I went a bit over-the-top and overkill... at the VRef stages I used 2 220uF Black Gate N caps per stage and put a 33uF Black Gate N at each shift register's power feed, replacing the existing small MLCC cap with a small (.22uF as I remember) PPS SMD film cap.
Sound... was good before, better now, with better bass extension and articulation, increased macro and micro dynamics, and better instrument separation. But about the same time I also got a couple of Twisted Pear Buffalo-IIIPro implementations running and in comparison, the treble extension and detailing of the Soerkis was well behind the ESS-based setups. After some thought, I decided to try some different options for the filter caps at the output of the shift registers. Not long after I first implemented the Soekris DACs, I had replaced the ceramic caps with SMD PPS films. Originally they had been 1500pF (for some reason that was what I thought I'd seen was there value) instead of the actual 1200pF there. I THOUGHT I had replaced those with 1200pF ones at some point, but when I replaced them with 1200pF AMTRANS polyprops, it was clear that the 1500pF ones had been there all this time. My subjective assessment was that while the 1200pF polyprops provided more detailed and extended highs, I thought they could still be bettered. On a whim, I tried some LCR 1200pF polystyrenes there and the gave the extended, detailed, and sweet treble I wanted. At first I thought they might not provide sufficient filtering, thought they have improved with burn-in time. But knowing 1500pF was too much, I have some 100pF & 120pF LCRs on order to parallel with the 1200pF and tweak the the level of filtering to my preference. I mounted the caps under the board at the raw output where I already had headers in place. Sorry, I didn't take pictures when I did this... will take some of this when I try the paralleled and post them here.
Not pictured are my 4 raw supplies... I have 2 sets of them (2 separate systems) either 7A Amveco or 4A (I said I like overkill!) with some nice 30A fast recovery IXYS HiPerFRED diodes into a 47,000uF Jensen 4-Pole cap per rail. As an alternative I can also power each rail with an Uptone Audio LPS-1 or LPS-1.2 with an adapter I made... Before the mods I slightly preferred the AC-connected supplies due to slightly greater dynamics, though they did not sound as refined and quiet. I haven't tried the Ultracap supplies since the mods, but will at some point. Also the 3.3V for the input side of the I2S isolators are powered separately too, either from another AC-supply (good) or another LPS-1 set to 3.3V (better).
Yah, way over the top with some serious overkill. Worth it? YES, to my ears. Of course, YMMV!
Greg in Mississippi
The recent mods are to replace all of the on-board regulators with upgrade units... starting with replacing the FPGA 1.2V regulator with an ldovr.com LT3045-based board and the FPGA/clock/other digital circuits 3.3V with the ldovr.com dual LT3045 board for a full 1A capacity. Each of these rails would now be fed from a separate power supply... overkill, but I'm into serious overkill!
In preparation for the mods around the processing side of the board I restructured some of my original implementation details such as my isolated and non-isolated serial port connections and the connector for the volume control pot (which I re-configured to make it the same as on the Twisted Pear Buffalo-IIIPro board, as I use the same cases/bases for them and didn't want to damage a DAC board if I swapped it into a case/base previously occupied by the other and didn't remember to swap the VC connector leads).
Back to the regulator mods, I took a great deal of care to keep the regulators close to the original feed points and the connections short. The ldovr.com boards made this work well and were a good alternative to the OPC dual 4||LT3042 boards (sadly no longer available) I had originally planned to use for these positions, as those would have required much longer leads.
Several mods back I'd removed the output stages when I started using the RAW output and in concert with the digital-focused regulator upgrades I also would be replacing the shift register regulators and feeding them from two more separate power supplies, so I repurposed the existing filtering cap array by totally removing the negative rail array (making room for the 1.2V replacement regulator) and installing 3900uF/16V caps in the place of the positive rail caps (these were through-hole caps, I used them by insulating their bases with Kapton tape and bending the leads outward to mimic the SMD cap lead arrangement). I used the 3 caps nearest the power feed for the 3.3V rail and by removing the small filter resistor between that bank and the final cap that originally was mainly used for feeding the positive rail of the output stage, used that final cap for the 1.2V rail. ALSO by retaining the power feeds into the original cap bank, it preserved the original mute functionality and made this set of mods much easier to plan and implement.
For the +-5V shift-register rails, I used a +- pair of Sparkos Labs regulators. Here, like above, I wanted to keep the regulators as close to the fed circuits as possible, so I mounted them on the output end of the board, re-using the space where the output stages had been. Then I fed the power and grounds from the regulators outputs directly to the reference voltage stages using carefully-installed 28 gauge insulated wire. These regs got 47uF Black Gate NXs on their outputs and mid-sized filter caps on their inputs.
I'd also done the VRef mods needed for my Rev1 boards a couple of years ago. Just like these mods, I went a bit over-the-top and overkill... at the VRef stages I used 2 220uF Black Gate N caps per stage and put a 33uF Black Gate N at each shift register's power feed, replacing the existing small MLCC cap with a small (.22uF as I remember) PPS SMD film cap.
Sound... was good before, better now, with better bass extension and articulation, increased macro and micro dynamics, and better instrument separation. But about the same time I also got a couple of Twisted Pear Buffalo-IIIPro implementations running and in comparison, the treble extension and detailing of the Soerkis was well behind the ESS-based setups. After some thought, I decided to try some different options for the filter caps at the output of the shift registers. Not long after I first implemented the Soekris DACs, I had replaced the ceramic caps with SMD PPS films. Originally they had been 1500pF (for some reason that was what I thought I'd seen was there value) instead of the actual 1200pF there. I THOUGHT I had replaced those with 1200pF ones at some point, but when I replaced them with 1200pF AMTRANS polyprops, it was clear that the 1500pF ones had been there all this time. My subjective assessment was that while the 1200pF polyprops provided more detailed and extended highs, I thought they could still be bettered. On a whim, I tried some LCR 1200pF polystyrenes there and the gave the extended, detailed, and sweet treble I wanted. At first I thought they might not provide sufficient filtering, thought they have improved with burn-in time. But knowing 1500pF was too much, I have some 100pF & 120pF LCRs on order to parallel with the 1200pF and tweak the the level of filtering to my preference. I mounted the caps under the board at the raw output where I already had headers in place. Sorry, I didn't take pictures when I did this... will take some of this when I try the paralleled and post them here.
Not pictured are my 4 raw supplies... I have 2 sets of them (2 separate systems) either 7A Amveco or 4A (I said I like overkill!) with some nice 30A fast recovery IXYS HiPerFRED diodes into a 47,000uF Jensen 4-Pole cap per rail. As an alternative I can also power each rail with an Uptone Audio LPS-1 or LPS-1.2 with an adapter I made... Before the mods I slightly preferred the AC-connected supplies due to slightly greater dynamics, though they did not sound as refined and quiet. I haven't tried the Ultracap supplies since the mods, but will at some point. Also the 3.3V for the input side of the I2S isolators are powered separately too, either from another AC-supply (good) or another LPS-1 set to 3.3V (better).
Yah, way over the top with some serious overkill. Worth it? YES, to my ears. Of course, YMMV!
Greg in Mississippi
Attachments
Pix of one of my 2 Soekris setups, this one fed I2S from an RPi stack with an allo.com Isolator board and Kali reclocker. You can see the filter caps from the 4 supplies feeding the DAC rails in the background, along with the 2 caps for the output stage supply, not used on my Soekris setups anymore.
The other setup gets I2S from an SDTrans384 SD card player.
The main supplies are connected via a couple of multi-pin Hirose connectors, which allows me to use the same supplies with multiple DAC setups. You can see the opening for the output stage connector in the Soekris DAC box... I removed the connector since I'm not using any output stages with these DACs, I have plenty of volume and drive into my high-impedance passive volume controls in my setups.
Greg in Mississippi
The other setup gets I2S from an SDTrans384 SD card player.
The main supplies are connected via a couple of multi-pin Hirose connectors, which allows me to use the same supplies with multiple DAC setups. You can see the opening for the output stage connector in the Soekris DAC box... I removed the connector since I'm not using any output stages with these DACs, I have plenty of volume and drive into my high-impedance passive volume controls in my setups.
Greg in Mississippi
Attachments
@Blitz,
Thanks.
I did not. I agree that is the best choice for an AC-connected supply, BUT honestly, I'm already taking up a LOT of space with the 7-8 supplies already implemented. IF I were doing choke supplies, I'd use John Swenson's supply as published a number of years back on Audio Asylum. Those would more than double the real-estate required.
OTOH, I'm moving towards even more exotic supplies. Using the Uptone Audio LPS-1/1.2 units which are AC-energized, but not AC-connected in use, are good first steps. I have run the setup as above with 7 of these supplies and intend to try powering the DAC with them too, which would push the total up to 11 in one setup!
Then there's even more exotic supplies such as direct Ultracaps... I expect to be trying those too in the next several weeks.
Greg in Mississippi
Thanks.
I did not. I agree that is the best choice for an AC-connected supply, BUT honestly, I'm already taking up a LOT of space with the 7-8 supplies already implemented. IF I were doing choke supplies, I'd use John Swenson's supply as published a number of years back on Audio Asylum. Those would more than double the real-estate required.
OTOH, I'm moving towards even more exotic supplies. Using the Uptone Audio LPS-1/1.2 units which are AC-energized, but not AC-connected in use, are good first steps. I have run the setup as above with 7 of these supplies and intend to try powering the DAC with them too, which would push the total up to 11 in one setup!
Then there's even more exotic supplies such as direct Ultracaps... I expect to be trying those too in the next several weeks.
Greg in Mississippi
Hi Greg,
You know Duncan's PSU Designer II, do you ?
You can see there the difference in ripple voltage/current spikes of a tPical CRC vs. LCLC supply....it is enourmous. I just converted my filament raw supply from CRC to LCLC and you hear the difference by a wide margin...reason being that the current spikes of a CRC which has 1A DC is like 5A from the diode pov...going down to 0.2A looking at ripple current...this is a lot of noise LESS in your psu, radiating into the whole circuit...this is not theory, I just tried it and this definetely is very audible...
You know Duncan's PSU Designer II, do you ?
You can see there the difference in ripple voltage/current spikes of a tPical CRC vs. LCLC supply....it is enourmous. I just converted my filament raw supply from CRC to LCLC and you hear the difference by a wide margin...reason being that the current spikes of a CRC which has 1A DC is like 5A from the diode pov...going down to 0.2A looking at ripple current...this is a lot of noise LESS in your psu, radiating into the whole circuit...this is not theory, I just tried it and this definetely is very audible...
Did anyone do experiments what the best DC supply voltage for the DAM is? I recently compared the sound quality of 10V, 12V and 14V and they all sound different. I would not opt for 14V as the dissipation would be unnecessary high (and I think that Soekris recommends 10-12Vdc). Still, I am not sure whether 10Vdc or 12Vdc sounds better (assuming sufficient headroom in the regulator board). I plan to build an Ultrabib 1.3 and need to choose between 12Vac or 15Vac transformers. Any opinions?
Fedde
Fedde
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