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Pizza Box v2.0 Class D amp project
http://dcaudiodiy.com/phpBB3/viewtopic.php?f=4&t=2240		 Page 2 of 2
Author:  tomp [ May 23rd, 2023, 12:23 pm ]
Post subject:  Re: Pizza Box v2.0 Class D amp project
Rich:

I forgot to mention that you should note SW101 which is an NO momentary push button switch. Unless that switch is manually pushed, the circuit will not start. That was done so that if the circuit drops out from a line problem, it will not automatically restart when the voltage comes back. Often the line voltage bounces back and forth and you don't want the soft start also bouncing on and off. If it drops out, which it has for me in the past, you have to make the decision when to turn it back on.
Author:  HAL [ May 23rd, 2023, 3:47 pm ]
Post subject:  Re: Pizza Box v2.0 Class D amp project
Tom,
Understand. Will add a manual start button to the code to keep it from restarting and just running.
Author:  HAL [ May 24th, 2023, 9:34 pm ]
Post subject:  Re: Pizza Box v2.0 Class D amp project
The SMPS to try. They are rated at 36VDC at 600W each for the +/-36VDC power supply and adjustable output voltage over a small voltage range. Yes, that is 1200W total power supply per module. Should be no problem for the 500Wrms into 4 Ohms rating for the amp modules.

Picked up the rest of the connectors today and the second pair of SMPS arrive tomorrow for the other amp module.

In the first test with a light load, both AC inputs tied together did not have a problem with a T5A slow blow fuse for startup. Will keep these as they will shut off the amps if to much current is drawn. A simple way to get started.

Will try a 100Ohm 25W resistor per SMPS tomorrow to try about 0.36A current load to see if they are stable and low noise with my o'scope.

Attachments:
SMPS-v1-test-small.jpg
SMPS-v1-test-small.jpg [ 1 MiB | Viewed 17653 times ]
Author:  SoundMods [ May 24th, 2023, 10:16 pm ]
Post subject:  Re: Pizza Box v2.0 Class D amp project
You might try mozzarella cheese for acoustic damping. :crazy:
Author:  HAL [ May 25th, 2023, 7:07 am ]
Post subject:  Re: Pizza Box v2.0 Class D amp project
Walt, no, I like Sorbothane of Navcom for damping. Cheese on my pizza is good. Don't let the boxes confuse you. :shock:

Have installed the input and output connectors in the box for the 2 channel amp.

The Pizza Box Amp +/-36V@16.7A SMPS ready for wiring to the amp modules. Using 14awg stranded Belden 1309 cables for the DC power.

Will add a capacitor bank to the amp module pizza box to lower the impedance at the amp end and help filter any SMPS noise further.

Attachments:
PBAv2-0SMPS&DCWiring.jpg
PBAv2-0SMPS&DCWiring.jpg [ 308.52 KiB | Viewed 17637 times ]
PBA-IOinstalled.jpg
PBA-IOinstalled.jpg [ 310.04 KiB | Viewed 17637 times ]
Author:  tomp [ May 25th, 2023, 7:25 am ]
Post subject:  Re: Pizza Box v2.0 Class D amp project
I heard that is a pretty cheesy way to achieve damping. :lol:
Author:  brombo [ May 25th, 2023, 7:49 am ]
Post subject:  Re: Pizza Box v2.0 Class D amp project
Have you measured the DC offset on the amps output yet and if so what is it?
Author:  HAL [ May 25th, 2023, 8:12 am ]
Post subject:  Re: Pizza Box v2.0 Class D amp project
brombo wrote:
Have you measured the DC offset on the amps output yet and if so what is it?


Have not powered them up, but they are DC coupled like the original version. From what I can read, they have a DC servo loop for DC offset.
Author:  HAL [ May 25th, 2023, 11:05 pm ]
Post subject:  Re: Pizza Box v2.0 Class D amp project
The monoblock versions of the Pizza Box Amp v2.0 are built.

Next it audio testing with an 8 Ohm dummy load to verify correct operation.

Attachments:
PBA-DualMonoCompleted.jpg
PBA-DualMonoCompleted.jpg [ 299.46 KiB | Viewed 17617 times ]
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