Author Topic: Chip amp in bridged mode  (Read 218 times)

John Lyons

Chip amp in bridged mode
« on: February 02, 2021, 03:31:51 PM »
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?




Basic Audio Pedals
www.basicaudio.net/

Gus

Re: Chip amp in bridged mode
« Reply #1 on: February 02, 2021, 03:47:12 PM »
What is the speaker ohm rating that you used in bridged mode?

antonis

Re: Chip amp in bridged mode
« Reply #2 on: February 02, 2021, 03:52:11 PM »
Try to ground pin 13 as close as physically possible to 150nF caps ground..

"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

John Lyons

Re: Chip amp in bridged mode
« Reply #3 on: February 02, 2021, 04:18:30 PM »
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.
Basic Audio Pedals
www.basicaudio.net/

antonis

Re: Chip amp in bridged mode
« Reply #4 on: February 02, 2021, 04:27:59 PM »
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..  :icon_wink:

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..)
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..