YjHifi 2x250w chip amp with bluetooth, gain?

[brighter]

Hi,
Can anyone look at this board and maybe determine how to increase gain?
Maximum output is too low for BT purpose - around 2x10w, and with same results driving it via line input with mobile phone.
Chip is tas5630r


Thanks for any info!

 

[nigelwright7557]

One option is a pre amp.

 

[brighter]

If this amp can not be gained higher, than preamp is the only option. But disconnecting BT receiver board and adding a preamp in between, sounds way too complicated for a novice.

 

[radiosmuck]

what ps are you using?

 

[radiosmuck]

From the images I have seen, there should be a big heatsink. Assembled TAS5630 High Power Class D Power AMP Board | eBay

 

[brighter]

It is meant to be used only with BT connection, and when gain is low, Psu and input voltage does not make any difference regarding output power.
Heatsink is removed for photo purpose only.

 

[irribeo]

125w into 8 ohm with 50v psu, 35w into 8 ohm with 25v psu, 10 watt indeed could be normal related to psu voltage

 

[brighter]

48v psu, 4ohm load.

 

[irribeo]

ok clearer now, in pic you see in front of two opamps four 10k feedback resistors, if you increase value you will increase gain

 

[brighter]

These four 10k resistors?


Any idea to what value if I wanted to increase gain by 12db?

Thanks, You are very helpfull!

 

[irribeo]

Yes seems logical to me that raising feedbackresistors to 40k brings 12dB more gain. But I am opampnoob. Making it an opamp question might bring very rapid answers though.

 

[brighter]

I swapped 10k with 40k and output is even lower and sounds like high pass filter.
Maybe 4 times lower resistance than?

 

[irribeo]

I don't think so, feedback resistor divided by grid resistor gives gain for tube, opamp too I guess, but is it feedbackresistor, TI 5630evm surely makes it look that way, so increase gives attenuation, are the opamps active, working? or does signal bypass opamps through feedbackresistor maybe, I really don't know, guessing here. I would create a thread in analog line level with opa1632 in title, circuit is 5630evm, increase feedback resistor gives reduced gain, I could be mixing things up.

 

[brighter]

After replacing 10k with 40k resulting decreased gain (who knows why), I have done several things to try to make it louder. Here is what I have done:

Not sure exactly how much dB I have gained, but I suspect around +10dB, which is fine for now...