When I used a 3255 with only 3 of 4 channels operating the fourth had a 8R 2W resistor in place. ( with input to ground through a cap )
Actually, the gain for each input is 21.5 dB at each output.
For BTL, the signal on output b is the inverted signal on output a, resulting in a doubling of the voltage across the speaker terminals, or a 6 dB increase. PBTL is the same gain, but double the available current.
I had to find out for myself. In BTL mode, I created a 400Hz signal at .64 volts and measured the speaker out voltage. It was 15.27 volts, which equates to a 27.5 dB gain.
Mike
For BTL, the signal on output b is the inverted signal on output a, resulting in a doubling of the voltage across the speaker terminals, or a 6 dB increase. PBTL is the same gain, but double the available current.
I had to find out for myself. In BTL mode, I created a 400Hz signal at .64 volts and measured the speaker out voltage. It was 15.27 volts, which equates to a 27.5 dB gain.
Mike
Thks doctormord, as you asked:
I gotten China-made FX502S-Pro which is a TPA3250 BTL implementation.
I am not sure how to go about config its custom PCB to PBTL, so could only take simplest approach now.
My bad, the sound WAS coming from the right speaker. Not sure how I missed it. Very high pitch whine. Normally when its not grounded properly, there will be a buzz, so I was probably not expecting high pitch noise. I lifted the ground for now, using a 3-2 plug on the power strip where both PS were connected and the whine has gone away. So much relief.
Load resistor keeps output happy...some have been known to destroy output filter caps when unloaded.
Input is now not open circuit...picking up noise for amplification to small load resistor.
I've finally tested my cousin of the 3255 the 3152, with mixed results. I'm using a 19V laptop power supply as a test case with a bottlehead foreplay II preamp. That combo resulted in quite a bit of hum. I then used my rasberry pimusicbox as a preamp and works great. I forcertain notice the bass improvment over the AVR (i think AVR's are designed to have less bass since most people use smaller speakers/sub so thats subjective) but will say I feel like the bass is very good at low listening levels. Plenty of power even with the 19v supply for my listening needs. Next step is to find a case and use it with my desktop computer system.
Speakers are chapman T7 which are moderatly efficient at 89dB SPL (1 meter, 1 watt) @ 4 ohms.
Speakers are chapman T7 which are moderatly efficient at 89dB SPL (1 meter, 1 watt) @ 4 ohms.
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Seems to be good! Note that for addidtional USD 6 you'll get 53.5 Vdc, exactly the voltage the TPA3255 is designed for.
Best regards!
Somethings not right with this PS, I think. I get no DC voltage reading. Fan goes like stink though. Sure Electronics' webstore Mean Well MW 36V 16.6A 600W AC/DC Switching Power Supply SE-600-36 UL/CUL PSU