PGA2310 buffer question

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Now my minimal PGA2310 volume controll is working, i think about a buffer.

From the datasheet: "[...] the capability to drive 600 Ohm loads directly without buffering" -- ok, no output buffe needed.

"[...] It is important to drive the PGA2310 with a low impedance . If a source impedance of greater than 600 Ohm is used, the distortion performace of the PGA2310 will begin to degrade."

ok, my CD player is 3k Ohm. Buffer needed.

Should i use opamp stuff like buf634, or would the simple single mosfet buffer from Zen V4 work also for the PGA?
 

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Sounds good that vol-ctrl is working!

Zen stage sounds rather tempting, but on the other hand there's an opamp in the PGA thingy anyway, so another opamp might be a natural starting point...

How about a simple opamp in unity gain...? E.g. Opa627, should work I think.

Those who like it can use a current source / pulldown resistor to bias it class A.

Should be fairly easy to try both Zen and opamp out that way,

/cdl
 
I have made some measurements of PGA2310 and 2311 with an Audio Presicion equipment. I used both unbuffered or buffered (inverting, noninverting) output. As outputbuffer I tried OPA627 and OPA134 (which should be the same as the one inside the PGA231x).

I could not see any differences in the output spectrum wheter it was buffered or not, I tried both 100k and 600 Ohms of load impedance.

The measurements where made with a rather crappy power supply, but I met the specs in the datasheets. One thing that could be taken into account when choosing between the two is the lower noise from PGA2311, but only if you can live with the lower maximum output.

The results made it clear to me that my next preamp should not have any buffering after the PGA.
 
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