[Magic77]

The AD8033/34 http://www.analog.com/UploadedFiles/...AD8033_4_b.pdf

I don't know how new these are, but AD calls them "FastFETs". The 8033 is the single version and the 8034 is the dual.

I just got both of them as samples from AD. I put both of them on browndogs and tried them out. So far, so good. They seem to work very well in the Pimeta. I'll have to listen a lot more to conclude any big differences from the AD8620's, but they do seem to sound quite good.

 

[ppl]

This Op Amp is a low power version of the AD-8065 and like the 8065 has issues with driving any amount of load capacitence. The data sheet cover states 33 pF of capacitive load drive, however this is at 30% over shoot. at this level the op amp is on the cusp of oscilation and compound that by operating the BUF-634 at low bandwidth and stability is down so far that the Amp in theroy should be unstable. To complicate matters tangent did not include a resistor between the op amp output and the Buffers input. He belives that since the Buffer allready has an input resistor that an external one is not needed. I disagree but since i had no involvement in the Pmeta it is what it is and i would be real carfull about randomly stuffing high speed op amps into it. The AD8034 might work just fine and if you have a scope available then do try it. look at the graphs on page 7 of the data sheet and note that evean at a gain of 6 severe peaking is present. I can see thgis in the Pmeta circuit as a stability nightmare. and in the ground channel real scary. However ymmy and who knowes there might be some bennifit to carrying around a transmitter operating at some unknowen frequency. while listening to your tunes.

 

[Magic77]

ppl,

Thanks for the detailed info. Looks like I better switch back to the AD8620/8610 combo.