No. 20 kHz not tested for full power - the Zobel circuit can burn.
I tested on 10kHz. Purely for fun. Distortion from switching floors power is almost not noticeable.
Interference from switching this is a typical problem of all amplifiers of this class. Therefore, it is important to do so that she didn't preisnachlass on low voltage and the input circuit. If this is not taken into account, then sharply increase distortion. It is also important to slow down switch to move the clutter spectrum in the low frequency region, where it is better suppressed feedback. However, this increases the power dissipation on the key, so you have to compromise. In the APEX amplifier a switching speed is very large, and therefore a hindrance switch has a hard spectrum, and given the small loop gain, its suppression will be small. In my amplifier was used a switch similar to those used in QSC RMX2450 amplifiers.
Last edited:
Yes the switching is allways problem with class H. I made a lot of study about it. Internal capacitances of the output/driver stage are the basic reason of it. The best way would be to reduce/eliminate this capacitances, however it's impossible. Another solution to reduce the series base resistors to the absolute minimum.
Controlled slew rate switching is the easiest way, but as You wrote it will increase the dissipation of the switching element. And not easy to find the best compromise.
You can also try speed up the amplifier itself, to be able the nfb to correct the switching noises.
But there is another way: Using modulated rail class H. This means more output devices, but my experience that they sounds much better. The only advantage of the switching is the less cost, and a little bit more power.
Sajti
Controlled slew rate switching is the easiest way, but as You wrote it will increase the dissipation of the switching element. And not easy to find the best compromise.
You can also try speed up the amplifier itself, to be able the nfb to correct the switching noises.
But there is another way: Using modulated rail class H. This means more output devices, but my experience that they sounds much better. The only advantage of the switching is the less cost, and a little bit more power.
Sajti
sajti, please compare this and Apex H900 floor switchers work - https://www.youtube.com/watch?v=yDeoWq8Cw7s
In that picture, where the disturbance is almost invisible, the form factor close to realistic, except for grounding the heat sink through the resistance of the filament of the incandescent lamp 15W
Feel the difference
In that picture, where the disturbance is almost invisible, the form factor close to realistic, except for grounding the heat sink through the resistance of the filament of the incandescent lamp 15W
Feel the difference
Last edited:
Feel the difference
I understood what You told. But my question: Are you sure that the only difference is the gronding of the heatsink?
Sajti
I'm thinking about Your results. I will try my solution on a prototype, and I will report the results!
Sajti
hi waso cool stuff
my 900h version based on apex design
http://www.diyaudio.com/forums/solid-state/162408-900w-h-class-pa-amp-limiter-315.html
my 900h version based on apex design
http://www.diyaudio.com/forums/solid-state/162408-900w-h-class-pa-amp-limiter-315.html
Thanks! Single board design, including the input, the protection, clip detector, temperature sensor, turn on delay.
expected output power 800-900W depending by the power supply.
Sajti