Chip amp in bridged mode

[John Lyons]

I've built this twice now on the breadboard at 9v
without success. I added an emitter follower/buffer
to get some more clarity for guitar.
It has a low oscillation with the buffer and sounds choked
and misbiased built just as in the image.
I have the Stereo/unbridged version working fine with the buffer.
I tried adding more filtering but I'm not sure where else to check.
Any ideas?

[Gus]

What is the speaker ohm rating that you used in bridged mode?

[antonis]

Try to ground pin 13 as close as physically possible to 150nF caps ground..

[John Lyons]

That's it! I moved a ground wire to put the .15 caps and pin 13
at the same point and it cleared up. Thank you.
I upped the 100uf at the output to 470uf also (before I changed the ground)
and that helped also. What is the affect of using .22uf rather than .15uf?

Gus:
I am using an 8 ohm speaker.

[antonis]

That's it! I moved a ground wire to put the .15 caps and pin 13
at the same point and it cleared up. Thank you.

You're welcome.. 

Next suggestion, in case of above non-effective, should be to delete one of 150nF caps and wire the remainder one between pins 2 & 15..
(to also prevent garbage entering into different points of GND..)