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RE: Nice work! Looks clean.

47.24.177.99

In Reply to: RE: Nice work! Looks clean. posted by Ralph on August 06, 2024 at 14:44:04

I have it hooked up currently and have been using it for a couple weeks now. I'm very happy with how it sounds. It has a lot of power reserve as you'd expect.

The distortion analyzer I currently have measures down to 0.03%. The amplifier measures 0.03% at low power and at full power from 20Hz to 20 KHz, so the THD is 0.03% or less. I recently purchased an HP339 analyzer but don't have it yet. It can measure lower than 0.03% so I'm curious if it's lower than that or not.

I have an RC filter on the input to roll off the response at 120KHz.

I'm posting the square wave response. The flat part of the trace looks a little thick but that's the oscilloscope, it's not an oscillation.

The only downside is that there is a little oscillation as it powers down. The Phase Linear 300 had a relay on the output and I'm going to use a relay on this amp as well.

Follow Ups:

Good to see those older Phase linears put to use. - Ralph 10:47:15 08/13/24 (1)
I am curious though- do you get the same distortion measurement at 7KHz?

It might be the amp is lower distortion than your analyzer can see...
- RE: Good to see those older Phase linears put to use. - Tiberius 12:36:48 08/13/24 (0)
  I retested the amplifier THD with an HP339 analyzer I just purchased last week. At 132 watts into 8 ohms, I measured the THD at 0.005% at 20KHz, 0.004% at 10KHz, 0.0015% at 2KHz and 0.001% at 500 Hz. Phase Linear rated it for 0.009% at 120 watts out and 0.002% at 1KHz, so my modifications meets or exceeds the original ratings. I doubt I could hear a difference between 0.05% and 0.005% anyway, but I am glad my circuit met the original specifications. When I bought this amplifier it was not working so I had no way to do a listening test between the original and my circuit. I'm happy with how it came out.

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