Transforming TPA3110 BD into ABD modulation.

[Hayk]

A smaller and cheaper enclosure can be used
I just found this on AliExpress:
US $6.32 | Aluminum Box Enclosure DIY Electronic Project Black Instrument Case 120x97x40mm

https://a.aliexpress.com/_c2zGIEZX

 

[Hayk]

I tested the below circuit successfully to alter expressive -mild character. I will add it to the filter board. It needs along the volume another potentiometer 2x250k.

 

[Hayk]

I tested the 2 channel board, it is a single chip. The bass is weak. I replaced the input capacitors with WIMA 1.5UF, not better. The gain is higher so less NFB and the resistors to adjust the gain are under the heatsink.

 

[Hayk]

I isolated the ground of the negative input capacitor with a scalpel to feed in differential with my interface, everything worked fine. I added 2.2uf upon shut down to give time the capacitors of the interface to charge.
I will modify the interface for 24v and give extra gain, so that it goes full power when the DAC or the Bluetooth is powered with 5v.
I am waiting for the inductors to finish the pcb.
I love this tiny smps.
The amp circuits will be sitting upon thermal conducting pads on the chassis to be cooled.

 

[Hayk]

This interface has a feature that I like it, even edicted to it, the mild to expressive adjustment. Unlike the 3255, this chip doesn't start up with differential dc, the interface must be at neutral position. I don't have now a simple solution for that.
The interface can be driven with differential input and yields very low distortion but no volume control.
I will add a step down 24v to 5v converter to supply external DAC Bluetooth and anti plop .

 

[Hayk]

This is an evantual anti plop circuit. I tested without opto coupler, it works well on start up. The output is standby. The opto senses the absence of mains 220v and shuts down. For 110v the 33nf needs to double. It will be a seperate pcb common for both channels, because of high voltage.
The interface will be seperate pcb fixed at the back along RCA inputs to be bypassed if differential input is selected, feeding the 3110 directly.
This opto coupler is very commonly used in power supplies, you can find in usb chargers.

 

[Hayk]

I am ĺistenenig comparative to lm3886 with xy board. I increased the gain of lm by replacing feedback resistor 22k with 33k to have equal level. The clear difference is the high frequencies, more detailed with 3110.
The small box including psu, no heatsink, less than $25 total cost for 2x25w @8 is a better quality for lower price.

 

[Hayk]

My anti plop circuit without opto coupler, shuts down when the 24v reaches 20v. The supply was decaying first losing sudden 3v which causes plop and then gradually to 0v. I added a regulator lm317L TO92 to run it with18v. Now no more plops at on and off. This is the circuit, is it the final?
This tiny amplifier, 120x97x40mm will be my reference amp which will serve me to tune the multiple 16bit dacs.

 

[Hayk]

This is the 2 channel interface with anti plop. It is 54x26mm.