Hi,
A friend of mine is interested in the Apex FH9 amp, and he asked me for an opinion.
As there were too many pages to look for the final schematic or any LTSpice simulations, I ended up using a circuit from a Russian site and made my sims with that.
Please have a look at my sims and do comment about them.
Sims are for THD, frequency/phase response and square wave.
For 106W @ 8 ohms, THD @ 1KHz climbs to 0.015%, and I've seen better.
For 20KHz it's worst, of course.
I made some small changes on the input cap to improve Frequency response a bit, and the feedback parallel cap to improve square wave response. Maybe it's not a good move. These changes should be listened to, really.
A friend of mine is interested in the Apex FH9 amp, and he asked me for an opinion.
As there were too many pages to look for the final schematic or any LTSpice simulations, I ended up using a circuit from a Russian site and made my sims with that.
Please have a look at my sims and do comment about them.
Sims are for THD, frequency/phase response and square wave.
For 106W @ 8 ohms, THD @ 1KHz climbs to 0.015%, and I've seen better.
For 20KHz it's worst, of course.
I made some small changes on the input cap to improve Frequency response a bit, and the feedback parallel cap to improve square wave response. Maybe it's not a good move. These changes should be listened to, really.
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Very nice build...I need to join the club urgently😉, I have the original renesas 2sk and 2sj from VSSA and basic FX-8 builds from long ago.
Regards
Prasi
At exactly 1.07W, THD @ 1KHz is 0.00166%. I bet it's probably better on other Apex amps.
What do you think about the cap changes I mentioned: 100pF at input and 5.6p in parallel with 22K? They seem to improve things on FR and SW.
Run the files I uploaded, if you can. And tell me if something should be corrected on the sim.
No you can't use 2SK1058/2SJ162. It has different pinout and it doesn't need Vbe multiplier. You would have to redesign the circuit and the pcb.
Wow! looks good! Have you build it? Is it ok? Can you share pcb design?
Sorry for all questions....Thank you!!
There is already a design by me fOr the basic fx-8, tested by many people.
Also there is fx-8 bimo mod, also tested by quite a few.
Also there is fx-8 bimo mod, also tested by quite a few.