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Current Source for PCM1794a DAC

95.147.213.3
Posted on August 13, 2014 at 04:55:11
DWJames
Audiophile

Posts: 3
Location: West Midlands
Joined: August 13, 2014
 Hi,
I was perusing your website and noticed in your digital section where you discuss your MKIV RAKK DAC that you say:
"Each of these DAC chips is receiving reference current from a new reference current source that we have developed, which is responsible for a dramatic improvement in sound quality"

I have a very tweaked DAC based on the PCM1794a (it's the DDDAC 1794NOS kit) and would love to try a current source for the reference current. Currently, I'm using a resistor as per the datasheet.

I guess my question is, would you be prepared to share the information about how you achieved the current source?
Maybe you would be interested in producing a small 2 pin CCS module which can be used in place of the resistor? I can see that would be a popular product if the results are good as you suggest.

thanks in advance,
James

James

 

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RE: Current Source for PCM1794a DAC, posted on August 13, 2014 at 09:14:36
Dave Davenport
Manufacturer

Posts: 916
Location: North Carolina
Joined: March 20, 2002
 James,

You have a sharp eye and a keen intellect in spotting that and assessing its worth. It is not just a simple CCS like we use elsewhere but an innovative design that took quite a bit to develop. This is only one of the several "secrets" that make the RAKK dac such an outstanding performer.

I choose to disclose the existence of a few of the innovations and choose to not disclose others. However, it would be foolish of me to give away the competitive edge of the RAKK dac by revealing the details of the innovations.

Dave

 

RE: Current Source for PCM1794a DAC, posted on August 13, 2014 at 15:16:33
JKT
Audiophile

Posts: 612
Location: Midwest
Joined: November 26, 2002
 You could replace the resistor with a simple JFET current source like the earlier RAKK DACs (1-3). Sounds better than a resistor, but not as good as the new one in the Mark IV.


"It is better to remain silent and thought a fool, then speak and remove all doubt." A. Lincoln

 

RE: Current Source for PCM1794a DAC, posted on August 14, 2014 at 08:08:24
DWJames
Audiophile

Posts: 3
Location: West Midlands
Joined: August 13, 2014
 Thanks guys.
Dave, I can respect that you want to protect your hard work. Any teeny pointers in the right direction you could pass my way would be gratefully received, but I understand if you want to keep it under your hat.

JKT, from what I've read so far, a J-FET seems to be the simple and easy choice for now, thanks




James

 

RE: Current Source for PCM1794a DAC, posted on August 14, 2014 at 19:18:47
Dave Davenport
Manufacturer

Posts: 916
Location: North Carolina
Joined: March 20, 2002
 James,

I would suggest that you go with what JKT has proposed.

Dave

 

RE: Current Source for PCM1794a DAC, posted on August 16, 2014 at 08:21:26
KevinC
Manufacturer

Posts: 2984
Location: NC
Joined: April 19, 2001
 You might try a couple of different types of JFETs for this to see what sounds the best. For example, a high transconductance 2SK170 and a low/med 2N3819.

Kevin Carter
K&K Audio
www.kandkaudio.com

 

RE: Current Source for PCM1794a DAC, posted on August 18, 2014 at 01:24:23
DWJames
Audiophile

Posts: 3
Location: West Midlands
Joined: August 13, 2014
 Thanks guys, that's great :)
James

 

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