I don't want to be snobbish/a pain, but it's really pretty important to get comfortable with the schematics in the EVM guide. http://www.ti.com/lit/ug/slou441/slou441.pdf
Page 17 shows pretty clearly that in single ended input, bridged mode, J3 and J18 are your inputs. Looking at J3, the input is buffered by u5a (inverted opamp) and then its output (pin 1 of u5a) is connected to pin 1 of J4. Now if you're doing single ended, you need pin 2 connected to pin 1, so the output of u5a is buffered and inverted by u5b. Voila, your differential input, to INA and INB. If you had a differential input (on J14), you'd connect J4 pin 3 to pin 2 to ensure the second side gets buffered by u5b.
Circuit is mirrored on the bottom end, so it's identical.
Page 17 shows pretty clearly that in single ended input, bridged mode, J3 and J18 are your inputs. Looking at J3, the input is buffered by u5a (inverted opamp) and then its output (pin 1 of u5a) is connected to pin 1 of J4. Now if you're doing single ended, you need pin 2 connected to pin 1, so the output of u5a is buffered and inverted by u5b. Voila, your differential input, to INA and INB. If you had a differential input (on J14), you'd connect J4 pin 3 to pin 2 to ensure the second side gets buffered by u5b.
Circuit is mirrored on the bottom end, so it's identical.
lrs-350 has a fan -- Hasn't been much of an issue for me?
Definitely could use the se-600 to power 2 modules.
And apologies if I was a bit grouchy -- have a look through the schematics and hopefully what I wrote makes a bit better sense. Also have a look at the basic circuit for an inverting opamp, and you can see how things are connected a lot more clearly. Then the board will be a whole lot less daunting to work on. Good luck.
Definitely could use the se-600 to power 2 modules.
And apologies if I was a bit grouchy -- have a look through the schematics and hopefully what I wrote makes a bit better sense. Also have a look at the basic circuit for an inverting opamp, and you can see how things are connected a lot more clearly. Then the board will be a whole lot less daunting to work on. Good luck.
The 350 has a fan but I've never heard it run. Either it rarely turns on or it's virtually silent. I'd rather run the amp with a power supply with more current but compromised on a power supply that others claimed was silent. They were right.
It's excellent sounding with the 350, too.
Totally agree. I do not think I have heard the fan inside the 350 came on. I purposely play at loud volume for 10-15 minutes (when the wife and kid were out of the house
) and checked on the PSU, nothing. Did not even get warm. My speakers are 87dB sensitivity, sort of average. I have a pair of panel speakers that are not easy to drive (83 dB), I am going to try it out and see what happens. I think the 350 is great value for money. Regards,
I'm pretty pleased with the sound of the TPA3255 and the 48v 350 watt power supply. Surprised at how nice it is.
Still curious about other power supplies, though. Anyone have any experience comparing a lower current switching supply to a higher current switcher? Anyone compare a switching supply to a linear supply?
Changing from a decent switcher to a decent linear and finally to a higher current linear made a nice improvement on the dac/Raspberry Pi. Each change in the power supply was clearly audible and to my ears an improvement in the sound. But that's only a 5 volt power supply and it's easy to find. 48v to 53v is a much bigger beast.
Still curious about other power supplies, though. Anyone have any experience comparing a lower current switching supply to a higher current switcher? Anyone compare a switching supply to a linear supply?
Changing from a decent switcher to a decent linear and finally to a higher current linear made a nice improvement on the dac/Raspberry Pi. Each change in the power supply was clearly audible and to my ears an improvement in the sound. But that's only a 5 volt power supply and it's easy to find. 48v to 53v is a much bigger beast.
ok quick question re input. if i have the same signal running to inputs a and b, both channels in btl mode driving single sub, with the jumper set to SE mode, will the extra identical input on channel b cause problems?
looking at the schematic it seems input b isnt actually connected to anything when the jumper is in SE mode, so it shouldnt make any difference?
i ask because testing my amp with sub drivers in free air (cabinets being cut now) , im getting nasty distortion even at low volumes.. doesnt seem to be any clipping anywhere ( i use a minidsp for input)
looking at the schematic it seems input b isnt actually connected to anything when the jumper is in SE mode, so it shouldnt make any difference?
i ask because testing my amp with sub drivers in free air (cabinets being cut now) , im getting nasty distortion even at low volumes.. doesnt seem to be any clipping anywhere ( i use a minidsp for input)
unfortunately i have built possibly the densest diy amplifier ever built, and getting to the spots on the amps where the inputs are connected would require an annoying strip-down (they are connected via those 3 pin headers, no rca jacks used.
im gonna post some pics once im happy its working.
anyway, i think i was possibly being an idiot. i had the subs on cushions so they didnt rattle on the floor, but just lifting them up in my arms appears to cure the distortion. surprisingly (to me, never done subs before) even pinning them to the floor with all my strength doesnt seem to cure the low volume distortion.. its some insistent vibration! but, conversely, picking them up does. definitely not the floor as its stone.
im gonna post some pics once im happy its working.
anyway, i think i was possibly being an idiot. i had the subs on cushions so they didnt rattle on the floor, but just lifting them up in my arms appears to cure the distortion. surprisingly (to me, never done subs before) even pinning them to the floor with all my strength doesnt seem to cure the low volume distortion.. its some insistent vibration! but, conversely, picking them up does. definitely not the floor as its stone.