[binary_digit]

Quote:

Originally posted by Voodoochile Sad but true.

I had hoped that it would not have to play a part in the engineering of these projects.

Sorry for off topic stuff
B_D

 

[eric343]

Quote:

Originally posted by ppl the Power entry module is a small IEC power conector inside a shielded Enclosure that contains the EMI filter.

Be warned that I have heard an incredible and *VERY* present rolloff in the highs when I used an IEC entry module+filter to deliver power to a linear p/s that powered a high-end META42. While I realize that the PPA is considerably more immune to power supply gremlins, I thought we're going for absolute fidelity...?

 

[tangent]

I'll be sure to run it past RMAA, then. Surely it should show up on the FR test?

I wonder why that should be. Any chance you were just hearing the lack of HF noise? I don't mean to imply that your hearing is garbage, but rather, did you also try a "reference" power source like NiMH batteries or a known high-quality wall power supply?

 

[morsel]

I can't imagine how a filter on the AC line of the power supply could cause HF rolloff in an amp. I think something else was going on with your test, Eric.

 

[eric343]

Don't ask me, all I know is the HF rolloff went away when I replaced the IEC with a non-filtered one. I posted about it awhile back... lots more details:

http://www4.head-fi.org/forums/showt...threadid=21402

 

[eric343]

Quote:

Originally posted by tangent I'll be sure to run it past RMAA, then. Surely it should show up on the FR test?

No idea... I think Tyll once said that very different amps show very little difference when you try to measure FR... Quote:

did you also try a "reference" power source like NiMH batteries or a known high-quality wall power supply? [/B]

Well, in that I tried the same amp with a nonfiltered IEC jack... and I knew immediately that something was wrong with the amp by the sound of it (having given a good listen to every amp I ever sent out, then hearing one sound WILDLY different...).

 

[aos]

If you use the word "rolloff" describing a phenomena, then it is definitely something that is measurable becuase you ARE talking frequency response.

Possibly you got some kind of oscillation in the power supply? In fact I remember that many regulators do not like rising impedance with frequency on their inputs, such as batteries have, and require capacitors of certain size on their inputs to combat that. It's quite possible that your filter had impedance as seen from output terminals that the regulator didn't like. Perhaps there was something wrong with that particular filter, or perhaps the regulator did not have the right capacitors (or they died).