Bandwidth question?

Orpheus10. That's all part of this. Sine waves don't really tell you much about the bandwidth of an amp or preamp since all your getting is the fundamental frequency without the harmonics. I tend to look at square waves. That tells me a lot about the amp or preamp I'm looking at. The reason is, a 1Khz square wave shows you not only the fundamental, but the harmonics as well. A perfect 1Khz square will tell me that this piece of gear is flat from 100Hz to 10Khz or ten times the fundamental frequency in both directions. It can also shed some light on the interesting things some manufacturers do with their output coupling transformers to make it seem like the transformer has more high frequency bandwidth then it really has. So for example for perfect 20kHZ square waves, an amp or preamp needs to have a bandwidth out to 200Khz. Sad thing is, it really won't tell you how the gear under test is going to sound. For that you need the best test instrument in the world, your ears.

Is the bandwidth thing the problem with 'd' amps? they drop like a rock somewhere around or just OVER 20khz in order to get rid of the switching noise. Early 'd' amps were also noted for RF effects. I once picked one up on a filling.
Going along with the steep frequency dropoff, which is also linked to load impedance with low impedance having a quicker dropoff, but you also apparently get some phase problems.

I'm saving my Pesos for a Pass integrated. (look for a website soon since i'll be accepting donations....'Pesos for Pass. org'. I'll buy it without even an audition. Just let me plug it in and give 'er a rip. Reasonable bandwidth, low feedback and near-impeccible square wave response. This won't be buying specs, either since virtually nobody who hooks 'em up to an appropriate speaker from SDFR to Panels has anything BAD to say about 'em.

Magfan, my class D Rowland 102 has 5Hz-65kHz -3dB bandwidth but I'm saving my Pesos for Rowland 625 with small possible temporary setbacks in the future like divorce, bankruptcy and foreclosure.

Right you are...
The open loop for the ASP500 module is 80khz@8 ohms and 60khz24ohms.
All at some specified tolerance.
Phase displacement is also noted......

While you don't have to be a "rocket scientist" to know what you hear, you do have to be a scientist in order to explain what you hear.

"Harmonics" are what separates the "high end" from "midfi". For example, if the fundamental frequency is 25 HZ, the frequencies of the harmonics are 50 HZ, 75 HZ and 100 HZ. Although the amplitude of the harmonics decreases in order, they determine the quality of the sound.

When you go to a live event, these harmonics are quite audible; they give the violin that rich tone and timbre, they resonate with each guitar note. These harmonics are present as low level detail at home.

If you have been to a live event and had that sensation of a sound that was ringing right in your ear, that was due to harmonics.