Ebay KSA50 needs 2 voltages?

[apoopoo999]

I found this ebay ksa50 clone, I built several amplifiers but this is the first time I seen one that needs 2 voltages. Can anyone explain this? The seller doesnt seem to helpful.

150W Class A KSA50 MONO amplifier board | eBay



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[mullardel34]

It's quite likely that the input/driver stages require a higher power-supply voltage level in order to allow the input/driver stages to drive the output stages rail-to-rail. See the Nelson Pass A75 design (http://passdiy.com/pdf/a75p1.pdf and http://passdiy.com/pdf/a75p2.pdf), which has a similar requirement for the power-supply design.

[apoopoo999]

hmm, so is it safe to say this clone is nothing like a ksa50

[stoc005]

If this was a MOSFET output and not a lateral FET output, the higher voltage for the input and driver stage(s) makes sense. But the outputs are bipolar transistors. I guess they want the amp to clip in the output stage with an extra 20 volts (p-p) of headroom for the driver/input stage.
2 oz platinum???

I don't see a bias or offset pot. How is that so??

[llwhtt]

Not just platinum but "COPPER thickness of 2 oz. of PLATINUM" WTF?

Craig

[john65b]

A KSA50 at 150 watts?

Did the Original KSA50 go into class AB?

Original output devices were a pair of MJ15003 and MJ15004

I think it is a low bias Class AB KSA50...should still sound nice...

Price is awesome, but can't help but think the transistors could be fake at that price...

I have a KSA50 with a trio of the 2SC5200/2SA1943 and it is my favorite amp by far.