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In Reply to: RE: Output impedance of a DAC to input impedance of Power amp?????? posted by Astrostar60 on August 10, 2014 at 12:36:39
Inserting the passive preamp means that you should be mindful of not running long cables at the output of the preamp.
The 10K passive's contribution to impedance isn't super cut and dry. Is it a constant input impedance (typical pot wiring), constant output impedance (shunt resistor variable series element), or neither (shunt pot series resistor).
The 10 Ohm output impedance of the DAC would seem to suggest that it will not be the limiting factor in your setup.
Follow Ups:
Hi Caucasian Blackplate (P)
Thanks for the information. The passive has 2 resistors in the path at any one time. so is probably the same output impedance at all times. The input impedance will go up as minus attenuation is used (turning the volume pot down).
Here is the unit I bought (stereo RCA with input selector):
http://www.khozmo.com/
Live long and listen!
The Khozmo will be constant input impedance.Edit - it's a fixed series resistor and variable shunt, so it's neither.
Edits: 08/11/14
With a shunt attenuator wouldn't the input impedance be Rx + (Ry//input impedance of destination) and change with every click?It would never be lower than Rx. Is that what's meant by "constant input impedance"?
To me the biggest concern is the output impedance.
With a 10k Rx, at -6db the output impedance of the attenuator is 2.5k (assuming an infinite destination impedance and zero source impedance).
Am I missing something?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 08/11/14
Yeah, I looked at all the Dale resistors on that attenuator and thought it was a conventional stepped attenuator, but now I see the fancy single series resistors.
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