CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS
Lobby => DIY => Topic started by: Mullet on March 04, 2014, 07:04:09 AM
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I know some of you mates have built this one, but figured I'd share some of my experiences with building the Curryman DAC. It has a JG buffer integrated.
http://www.minidsp.com/products/minidspkits/curryman-i2s-dac
I had the opportunity to build one of the beta test boards. For size reasons, I chose to use AMB's Sigma 25 for power supplies. Two of the supplies used at 15v a pop and wired them up to provide 15-0-15. And the other to provide 5v to the DAC board and Acko Amanero Isolator/Re-clocking board. I used an Amanero Combo384 for USB to i2s transport. No other inputs. This was made for computer usage only. I set it up to be able to switch pre and post buffer.
I would have liked to try higher quality power like a Salas shunt, but couldn't source a board at the time. Overall, I'm pretty impressed with the sound quality. The JG buffer really takes the edge off the 9023. I'm pairing it with The Wire amp. The sound is nice and detailed. It's not as warm as my Gamma 2 DAC, which I view as a good thing.
My interest is really piqued for what better supplies could provide. I have an Acko AKD23P for the next go around. This board allows for a separate JG Buffer board as a daughter board. Also have the Salas boards now and the option to use a Wire PSU board for JG power supply. So I'm contemplating going balls to the wall.
Anyways, here are pics of the Curryman in action... :wheel:
(https://lh6.googleusercontent.com/-vwsYpYMoRVs/Ulzfh_ci9hI/AAAAAAAAATk/Sbg4g8bFccs/s912/DSC_0581.jpg)
(https://lh6.googleusercontent.com/-1IKp9E-hIsM/Ulzfh6YSjFI/AAAAAAAAATs/PEKVjbJgbvo/s912/DSC_0577.jpg)
(https://lh6.googleusercontent.com/-wVjoFneBPU8/Ulzfh7gKGdI/AAAAAAAAATo/54vuvRsoJ5o/s912/DSC_0578.jpg)
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Nice build in all aspects.
(http://th03.deviantart.net/fs36/200H/f/2008/277/d/7/Big_Boss_salute_by_CynicPirate.png)
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Looks great.
To get a reference, what's the dimensions of that Hammond chassis you used?
I need an excuse to build a DAC... or do I? :&
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I know the feeling. I just bought a PINT pcb and a PPA SMD pcb. Do I really need two more portable amps? Nope. Gotta feed the addiction. p:3
The case is actually custom. It's internal dimensions are 9" x 8" x 2". The wood panels make it 10" across.
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Really nice build mate! I'm putting together a curryman too. Picked one up awhile a go, and your build has me intrigued.
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With my next build I'm going big in two ways... Synchronous clocking -- I'm going to use Acko's Re-clocking board that uses the Potato Semi chips in conjunction with one of his clock boards. The board takes two clocks. I'm still not sure whether to bypass the Amanero clocks or not. Another consideration is to power clocks with LIPO batteries. The second upgrade would be using better power supplies, which I previously mentioned -- Salas BiB LV Shunt and/or The Wire PSU. With this one I might even up the ante and go with something like the Twisted Pear OTTO 2:1 MUX to allow for SPDIF input as well.
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What about a FIFO buffer? Misterrogers reported great results with the SABRE implementations using one.
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Luuuurve the chassis! That stuff's clean.
The second upgrade would be using better power supplies, which I previously mentioned -- Salas BiB LV Shunt and/or The Wire PSU.
Try a series regulator with lots of feedback. The Salas shunt is nice, but its output impedance gets kinda crazy at high frequencies. Here's a series regulator with a simple error amp, based on a design from DIYaudio that I can't find at the moment but that's quite good. Less part, and lower output impedance- I'm planning on using a variation of this in my DAC.
(http://i.imgur.com/MkCk3nGs.jpg) (http://imgur.com/MkCk3nG)(http://i.imgur.com/sGt58XWs.jpg) (http://imgur.com/sGt58XW)
(http://i.imgur.com/3lTWTyIs.jpg) (http://imgur.com/3lTWTyI)
(clicky for big)
I'm not sure if it's the latest and greatest, but Salas shunt sims are here: http://www.diyaudio.com/forums/power-supplies/143693-simplistic-salas-low-voltage-shunt-regulator.html
You can probably do better with some tweaks. :) A small cap, 1uF or so, with a 1 ohm series resistor will ensure that the output impedance stays under an ohm in the higher MHz while preventing the output from oscillating. Stacked film or np0 ceramic, or even high ESR electrolytic would work well here, with additional bypassing at the chip itself. This might work better than LiPo as well- double check the output impedance and noise figures on those.