Orange micro crush power amp IC

[disorder]

I just picked one of these Orange micro crush amps up. It's a 3W RMS rated portable amp that runs off either a 9V batt or 9-12V power adapter. I found that the one I bought was quiet even at full volume using a 12V 1A power adapter so I opened it up. I found a fairly basic TL072 circuit feeding a TBA820ML power amp IC. The datasheet for this part says it can handle 1W max at ambient temp. There is no heatsink on the chip in the orange amp. How can they rate their product at 3W RMS? I could see a 3W peak rating but there is no way this thing can output 3W. Even with the volume cranked and a boost pedal in front I'm finding it weak sounding compared to the few LM386 designs I have built (ruby, cricket, etc...).

http://www.mycomkits.com/reference/TBA820.pdf

[disorder]

This is interesting, I found a blog run by someone named mylk who happened to open his Micro Crush amp up. The pcb in his amp looks identical to mine except where I have a measly 8-pin 1W TBA820 chip his has the 16-pin 3W TDA7267. 

http://www.mylkstuff.com/userimages/Orange/OrangeMicroCab-Circuit%20board.jpg
http://mylkstuff.com/page12.htm#137001

[stringsthings]

Looks like mylk posted this back in 2013.  Looks like Orange changed the IC, but didn't change the description of "3W RMS".

[bool]

TDA7267 isn't only able of higher power handling (and dissipation), it also swings the output closer to the rail voltage (not quite R-R, but close enough); while the older design TBA820M isn't capable of such voltage swing.

What you could try (but don't blame me if you fry the chip) is to bump the power voltage to 15V (not a mV more) AND attach a small heatsink to the chip - see if you can get some Raspberry-Pi stick-on heatsinks - or old computer RAM stick-on heatsinks.

One of things to consider is that TBA8xx chips tend to sound "weak" when they heat up - so try to determine that your chip isn't overheating already.

Note that I'm not familiar with the particular Micro Crush circuit; but I'm quite familiar with the "power" amp chip you've got.

The TBA chips are in general somewhat sturdy; but I have definitely burned up a certain amount of them in the past - they were popular in the '80s. (Worked with TBA800, TBA810 and TBA820 14-pin and the small 8-pin one).

So proceed with caution.

[Mark Hammer]

Useful advice. I have a dual TBA820 board that I want to try out as a small stereo amp.

[bool]

Small cheap TO126 U-profile heatsinks can also be fixed to the chip if you have some stick-on thermal pad.

Other than that, if you yet have to design a "amp board", the easiest fix with the 820 chip (or any in classic-shape DIP package) is to mount them on the PCB's trace-side (bottom-side), twist the legs and mount the board so that the chips have nice surface contact with some metal surface (enclosure or something).

Also works for the "winged" types, but these are afaik long deprecated.

[disorder]

I purchased another Orange Micro Crush, this one a "2nd gen" and it also has the 1W TBA820ML chip. I'm going to test this amplifier at work to see just what kind of power it outputs. I will likely send an email to Orange to see if theres a way to tell if I'm getting the TBA820 or the TDA7267. I find this a little frustrating...