I am not going to argue either way as I don't have the experience but this is how I was putting it together in my head. I was summing the quiescent current of each output device. So IF I could idle the outputs at .75amp I would have 3A across the 80V peak to peak or 3*.707 = 2.12A rms
2.12*2.12*8= 35.9Wrms at 8ohms?
Is this accurate?
2.12*2.12*8= 35.9Wrms at 8ohms?
Is this accurate?
Then that's what I'll do 
I cleaned, re-greased, and reset the transistors. Mounted a 5 inch 12v DC fan and running it at 5v. Idling at .165v a at .22 ohm emitter resistor so .75A per device.
All is barely warm to the touch with the transistors not being too hot to keep you finger on.
Pulling 4 amps per channel off the secondary winding or the toroidal and 2.3 A at 155V out of the wall.
Not sure if i need a soft start as there did not seem to be too much effort in the cold charge when firing it up. (90,000 uf).
Next, put in ammeters for fun and connect a source and speakers.
I am sharing a power supply for both channels so i will run the gauges at + and - total for both channels.
I cleaned, re-greased, and reset the transistors. Mounted a 5 inch 12v DC fan and running it at 5v. Idling at .165v a at .22 ohm emitter resistor so .75A per device.All is barely warm to the touch with the transistors not being too hot to keep you finger on.
Pulling 4 amps per channel off the secondary winding or the toroidal and 2.3 A at 155V out of the wall.
Not sure if i need a soft start as there did not seem to be too much effort in the cold charge when firing it up. (90,000 uf).
Next, put in ammeters for fun and connect a source and speakers.
I am sharing a power supply for both channels so i will run the gauges at + and - total for both channels.
Photo and update
Here is is so far. More of an experiment than an amp. It does sound nice so far. Very effortless. Problem is that the Arcam A75+ that i am using for a pre-amp kicks out before my meters even move from 3 amps. I Think the output may be too low for the amp's input stage. Just guessing there though.
Toroidal heats up some. If I am drawing 8A across 80V does that equate to a 640VA?
the toroid is good and warm but not what I would call hot by any means. How would I calculate the max VA of the transformer?
Thanks
Here is is so far. More of an experiment than an amp. It does sound nice so far. Very effortless. Problem is that the Arcam A75+ that i am using for a pre-amp kicks out before my meters even move from 3 amps. I Think the output may be too low for the amp's input stage. Just guessing there though.
Toroidal heats up some. If I am drawing 8A across 80V does that equate to a 640VA?
the toroid is good and warm but not what I would call hot by any means. How would I calculate the max VA of the transformer?
Thanks
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I have had both the A75+ and P75+ apart and they are both clean without burnt components. Actually neither amp can be pushed at all with no load or the small load of the tweeter in my bi-amped configuration. Both amps perform the same and have since new when I bought them. Oddly, when I bi-wire to iether of the two the problem goes away and I can get a lot more volume from just one amp. Low sensitivity Spendors but still an apples to apples experiment.
output vs. input line voltage
Folks. Here are the schematics and CAD drawing for the KSA50 boards I am using. If I drop the resistance of R22 (1K) will I increase the gain based on a higher voltage in? I don't think that the voltage line out from my Arcam is as high as it should be for the input on this board.
Does that make sense?
Folks. Here are the schematics and CAD drawing for the KSA50 boards I am using. If I drop the resistance of R22 (1K) will I increase the gain based on a higher voltage in? I don't think that the voltage line out from my Arcam is as high as it should be for the input on this board.
Does that make sense?
Nice to see some posts about these. I bought a pair but I think I am out of my depth with them. I honestly dont see the point of building them if I cant get them running to original spec without blowing up. I can get 16 watts out of a 845 with less trouble.
When I bought them I thought all I had to do was buy the right trans and some caps and heatsinks and fire them up. I bought a lower power zen maybe that might be a less chantsy option though I will follow this post with fingers crossed.
dont forget the cheap naim boards. They could be a cooler running option. cheers
When I bought them I thought all I had to do was buy the right trans and some caps and heatsinks and fire them up. I bought a lower power zen maybe that might be a less chantsy option though I will follow this post with fingers crossed.
dont forget the cheap naim boards. They could be a cooler running option. cheers
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