Ping: Monkey Bones, PCM1704 talk

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Hello
I found the following:
>>Posted by Monkey Bones ( A ) on October 13, 2005 at 09:17:24
In Reply to: Passive low pass filter for last stage in a CD player posted by legarem on October 13, 2005 at 05:33:54:
You can do it with no problem, and I have used that approach in the past with the 1704, even using a 50 to 100 ohm resistor terminated passive LCR filter on the output of the DAC, but I recommend using a virtual ground on the output of the DAC as the jefemeister suggests because it just sounds better, at least when implemented with a good discrete design. We had a discussion over on the computer forum about this recently including posting various circuit topologies, and I did experiment in the past with resistor I/V on the 1704 and concluded after careful level matching and critical listening that the sound improves down to below 10 ohms, which is impractical to implement as a passive I/V since it would require a gain of about 300 after and is just too noisy. So I just went with a simple zero feedback current mirror using a couple low noise bipolars which gets me down in the 4 ohm range with very low noise. And just followed it with a simple single ended cascoded mosfet high bias output stage. I designed my own since it was in the late 90s and there wasn't too much info around then in regard to the 1704, but there's tons of designs out there now with any flavor circuit element you could want :-)
>>
Question:
1. If resistor for I/V dac out should it be foil? Best resistor?
2. Where do I find:"1704, but there's tons of designs out there now"
Note: I would very much like to "play" around with the analog out on I out dac's as the opamp concept from TI on the 1704 did not sound good to me at all (my layout may have ben bad ). I think it is less of a layout problem if I use a resistor to ground, and find the point where noise and distortion are balanced uptimized.
Thanks.

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Topic - Ping: Monkey Bones, PCM1704 talk - jensw 05:34:50 09/26/06 (4)

Re: Ping: Monkey Bones, PCM1704 talk - John Swenson 20:39:52 09/26/06 (0)

Whatever happened to Monkey Bones? - Slider 08:25:07 09/26/06 (2)

Re: Whatever happened to Monkey Bones? - jensw 11:46:46 10/02/06 (1)

Re: Whatever happened to Monkey Bones? - Slider 07:57:04 10/03/06 (0)

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