Pioneer chip-amp AVRs

[dvenardos]

I am stealing this because it looked like an interesting topic to me:

As I've posted many times, the best bargain receiver is the Pioneer 919 with the chipamps, especially for high efficiency speakers. They can be had for around $350 with a ton of features and the best room correction available in the price category.

http://www.pioneerelectronics.com/PUSA/Products/HomeEntertainment/AV-Receivers/PioneerReceivers

http://www.bigpicturebigsound.com/Pioneer_VSX-919AH.shtml

http://www.avhub.com.au/ProductReview.aspx?MagazineID=5&ProductReviewID=394

[Cujobob]

I believe I have quotes from Dr. Geddes somewhere, let me see if I can copy and paste them into this thread. He picked up a number of inexpensive receivers and came up with his own testing method to determine their sound quality. The Pioneer chipamp receivers (only a few models use them) actually tested the best.

Also here: http://www.tweakcityaudio.com/forum/...1&postcount=25



From this thread:

http://www.diyaudio.com/forums/solid-state/109147-geddes-distortion-measurements.html

"Crossover distortion is a particularly insideous form of nonlinearity because it happens at all signal levels and there is no comparable mechanism in a loudspeaker to mask it. The question was asked if I have a way of identifying crossover distortion in an amplifier.

Yes, I do.

You see the situation with crossover distortion is that the % distortion increases with falling signal level. This is exactly why it is so audible since this is directly opposite to our hearing.

One could therefor ***** crossover distortion by looking at THD as the signal level goes lower, which is a typical measurement. The problem is that virtually all of these THD versus level measurements are THD + noise. When this is the case, the rise in THD at lower signal levels is actually the noise and NOT the distortion, but it is impossible to tell which is which. SO this test actually masks the real problem. One would have to track the individual harmonics of the waveform, but then the noise floor is still an issue.

Hence the measurement problem is one of noise floor and how to measure distortion products down below this floor.

This is done by averaging. But normal averaging can only lower the noise floor so much - down to the noise power. But if I have a signal and I average this signal sychronously then I can raise the net signal to noise level. This too is common. But if the signal does not exactly fit the time base then I need to window it and the resultant spectral leakage makes this sychronous averaging less effective.

I use a signal that exactly fits into the time base of the A/D taking the data. This means that I don't have to use a window and I can sychronously average a signal to noise ratio that is about 20 dB better than a simpler test could achieve. This means for example that the input signal needs to be something like 976 Hz, not 1000 Hz, which doesn't exactly fit the window.

I actually had to generate the input wav file in FORTRAN using quad precision, special random number generators and rounding techniques, because the test signals needed to have a 120 dB dynamic range - very difficult with 16 bits.

I use a signal that starts out low and goes up in level. I plot out the results as the signal drops into the noise floor. This test shows vast differences in amps that measure identical with standard tests.

It also shows that my Pioneer amp - you know the "really crappy" one that I get crticized for using at RMAF - is an extremely good amplifier. As good as the best that I have tested with this technique. "

[dvenardos]

Thanks, do you know which models use them? It isn't apparent from Pioneer's website.

[Cujobob]

The way they describe their amplifier topology for each model tells you (just not in plain english). I know the 919 and 1019 do.

It sucks that the prices are steadily rising...they were as low as $320 at one point for a 919 and now they're upto $390 most places.