Class D amp Regulated power supply??

[DionG]

Hi, so I've got a situation where involves powering 500W of Class D amp boards (TA2022) that need 22-0-22 AC input. (The boards are premade and designed by someone else).

I have a 27-0-27 transformer which i want to use to save me spending the extra $80 and buying a new one.
Could i rectify it and use a linear regulator circuit here to drop the 38VDC to to the required 31VDC?? (and take out the rectifier stuff on the amp board). ie would my heat sink have to be so big its not worth it? and I've read in places that it affects the bass output as the high current pulses are limited by the regulator? and any other problems?

I also thought about taking a few winds off the transformer secondaries as its a toroidal. do you think this would be better? although i do like the idea of a regulated PSU wish next to no ripple compared to the unregulated.

thanks
Dion

[luka]

you could this, or add turns to the primary... I think it would still work, without using drop regulator, which is always an option

[DionG]

yea i think adding to primary would be easier and i would only have to do it once rather than both secondaries.

I would still rather do it regulated if possible. Do you think something like
High Current Voltage Regulation - Electric Circuit would work?
or even
PA100 DIY 2x LM3886 in parallel gainclone audio amplifier ?? (this one even gives the right voltages)

Dion

[luka]

indeed it would work, I would just have some capacitance after regulators, to increase peak power of the supply

[!]

TA2020 can take +-36V input per the datasheet. 27-0-27 transformer would give you roughly 36.7V... you could leave the rectifier stage on the amp board to drop that down to about 35.3V.

Regulation does not have nearly as much benefit on a class D amp, but yes you could do it if you wanted to anyway, using pretty big heatsinks. However, supplying 500W worth of amp(s) with ~ +-35V input, the PSU would need be capable of more current than either of the designs you linked (first link would need a different transistor rated for higher current).

[DionG]

I know they can take that 36V but i have the two amp boards below they it will be powering. Both have the required voltage at 22v transformer.
The reason I'm hesitant about putting the higher voltage into them is because they have other chips on the board controlling things like the speaker protect (3 sec delay and DC detect). I don't have datasheets on the boards or even what some of the other chips are hence I don't really want to take that risk of putting in the high voltage.
It says it uses C1237 speaker protection circuit. But if anyone has experience with these and knows they will handle the voltage, awesome.

Amp Boards:
2x 180W AUDIO Stereo TA2022 Amplifier Amplifer Board | eBay
Improved 90W+90W TA2022 speaker protect amplifier board | eBay

I know the heat sink would have to be big but are you able to give me an idea of what sort size I'm looking at? because if its too big, adding extra winds to the primary it is

Thanks
Dion

edit: as for the current handling of the regulators. they supply is actually split into 3. 1 for the small board (tweets) and two for the main board (left and right) so the 7.5A would do it on the 2nd link. My reason for spiting them is do to with issues of ground loops (i think, or some sort of loop) when a single supply is powering multiple amps). do you think this is unnecessary?