Hi all,

I have Yamaha HTR-6130 Dolby/DTS/THX surround decoder with 5 active outputs and additional output for connecting an active subwoofer. I have 2 front speakers + surround and central speakers from Sony HCD-S800 surround system, part of which is Sony SS-WS500 100 W subwoofer.

I am looking for an amplifier schematics so I could use that subwoofer with the mentioned Yamaha decoder. The subwoofer's impedance is 3 Ohm and the desired cut-off frequency I would like to be around 120 Hz (cut-off frequency is selectable from the decoder menu but LFE surround channel goes to the subwoofer as well).

I would appreciate any help in finding the appropriate schematics for driving that Sony subwoofer.

 

Looks for some class d amps. You don't need great sound quality here.

 

Yes, the subwoofer output has 10% THD anyway. However, in the meantime I've found this $5 TPA3116D2 based 100 W amplifier and seems there isn't point in making one by myself. According to TPA datasheet, the output when using 23 V voltage for the power supply and 3 Ohm speaker is around 100 W.

Thank you for the reply!

 

According to TPA datasheet, the output when using 23 V voltage for the power supply and 3 Ohm speaker is around 100 W.

You just need to be careful with those claims. Do some math of your own.

 

There is maximum output power vs supply voltage characteristic on the page 12 of this Texas Instruments TPA3116D2 datasheet. From the characteristic the output power when using 22 V supply is about 70 W (THD = 1%) or around 90 W (THD = 10%). Texas Instrument's datasheet should be correct, shouldn't it?

Although I am not sure how to determine when to use the blue and when to use the red characteristic. I suppose THD first has to be determined according to the input level.

 

the amp works in btl. the theoretical max output voltage (peak) on the load would be supply voltage, assuming no loss on the output devices.

That works out to be 24^2/3 = 192w. RMS power is half of that, or 96w.

the datasheet shows output low voltage of 0.8v (max), no specification for loss on output high but assume that's 0.8v as well. the peak output power is (24-1.6)^2/3 = 167w peak and 84w RMS.

and you may breach the max output current ratings for some chips here. So you may have to parallel the two amps and use them as one mono amp - likely some loss of inefficiencies there.

...

the point is to do your own math.

 

So you may have to parallel the two amps and use them as one mono amp - likely some loss of inefficiencies there.

According to the TPA datasheet, it already has build in option to use both channels as one mono channel.

Thank you for your replies!

Regards