Need some answers, Less power than datasheet.

[xXBrunoXx]

Hello, I've built a small amp with tda2050. Single power one not split.. Powered by 32vcc - GND. And I only get 5v rms (just before clipping)at 1khz in 6ohm, so not even 6w.
Transformer is way oversized so no problem here also 10.000uf filter cap.
The tda2050 i took out of a 5.1 subwoofer that i haven't used anymore, but it worked, so i guess it's not fake tda2050. So 4.16W at 32v supply sounds very low to me, what do you guys think?.
Datasheet schematic, only difference is I've used 100k resistors for R1-R2-R3.
But they just make the voltage half at the output, so i guess it's not theyr fault for being 100k instead of 22k or am I wrong? ( i had PCB already, with 100k resistors in there, the rest is the same)
The feedback resistors are 100k and 4.7k so 22gain instead of datasheet 22k 680ohm 33 gain

 

[xXBrunoXx]

Tested it on 46vdc. 18w before clipping in 6ohm (data sheet says 18w 8ohm, 28w 4ohm at 0.5thd) so now im close to what ''it should'' do. But im still confused why so low power at 32vdc.
I wanted to use it on my Boombox on 16 li ion batteries, 8 series 8 series then parallel so 4.2v x 8 = 33.6v at 4amps (2amp per battery)

 

[TBTL]

What dc voltage do you measure at pin 1 and pin 4? Does it clip symmetrically?

 

[xXBrunoXx]

I have 1/2 voltage at pin 4 its normal, maybe it can't give more than 5w at 32v on 6ohm. On 46vdc I got 18w in 6ohms.

 

[asuslover]

I would replace c7 1000uf with 3300uf or more. And measure again, how big is the heatsink?

 

[xXBrunoXx]

C7 is 2700uf
Heatsink gets just warm (only one channel) 15x5x4cm

 

[FauxFrench]

I have 1/2 voltage at pin 4 its normal, maybe it can't give more than 5w at 32v on 6ohm. On 46vdc I got 18w in 6ohms.

This is surprisingly little compared to the datasheet pages 7 and 8. Have you tried to see the voltage swing without load?

 

[xXBrunoXx]

I haven't, too bad i can't anymore. I've mounted it in the Boombox, 5w it's not what I've wanted, but it gets pretty loud

 

[Kshishtoff]

And how do you measure output power?

 

[xXBrunoXx]

Tried 400hz and 1khz into 6ohm load, measured output voltage with analog and digital multimeter, i dont have an osciloscope yet.

 

[Kshishtoff]

Did you measure the output voltage like on attached pic?

 

[xXBrunoXx]

I ve just put the multimeter terminals tobthw output (while the load was wired too). It's pretty accurate, I've measured my pioneer amp that's its specs are 130w per channel into 4ohms and I measured 24v rms before right before clipping.