Focus on 24/192 Misguided?.....

Kijanki, u could have answered your own question about ultrasonics from 192K sampling now that you have answered the question of power bandwidths of power amps. Now you can see why a power amp would be nonlinear in the ultrasonic range & why those ultrasonic intermod distortion products folded down to the 20-20K. Now , the amplitude of these ultrasonics might not be large enough but better not to have them at all.....

Excellent post by Kijanki. I agree completely.

04-22-12: Bifwynne
... do you know what the power bandwidth is on ARC amps, particularly the VS-115. Freq. response is approx. 100K, but I don't know if that is the same as power bandwidth.

My understanding is that unless otherwise stated frequency response and bandwidth are usually specified under "small signal" conditions. I believe that for power amplifiers "small signal" is commonly defined to mean 1 watt or 2.83 volts (2.83 volts corresponds to 1 watt into 8 ohms). Full power bandwidth will sometimes be considerably less, in part because in some designs it will be limited by what is called slew rate, which isn't a factor under small signal conditions.

The specifications at the ARC website do not appear to indicate either full power bandwidth or slew rate for your VS-115, so there isn't enough information to answer your question. As Kijanki indicated, though, high power levels are not required at ultrasonic frequencies, so small signal bandwidth is a more meaningful number than full power bandwidth.

Returning to the question of ultrasonic intermodulation distortion, I'm not sure that bandwidth limitations are directly relevant to the issue, although they might play a role. What is relevant is non-linearity. As long as the amp's output amplitude is linearly proportional to input amplitude, at each of the frequencies for which an ultrasonic spectral component is present, there won't be a problem. Perhaps there will often be a tendency for linearity to degrade at frequencies where the amplifier's small signal frequency response is rolling off, in which case bandwidth would have some relevance to the issue. Or perhaps not; I have no particular knowledge on that question.

Best regards,
-- Al

Thank you Al. If there are any harmonics within 50kHz amplifiers should be still linear (modulation can only happen on nonlinear element). Any problem would already show with vinyl gear that has similar bandwidth. I don't really see any source of audible harmonics above it. On one hand studio engineers would clean it up but on the other microphones already do it. Most of microphones go only to 30kHz and some extended response go to 50kHz. One of the most popular Neumann U87 ($3600) goes only to 20kHz while the most expensive I could find Sony C-800G ($8000) is only 18kHz. At the concerts as well as in the studio nothing goes directly - everything comes thru microphones to PA system or studio console. Further more, I suspect that studio equipment bandwidth does not extend any higher providing natural filters as well.

Al and Kijanki, not sure this is relevant about extended bandwidth, but when I play the Four Seasons/Jersey Boys, I hear neighborhood dogs howling when Frankie Valli hits the high ones. LOL

Bifwynne, LOL