Squealing ruby

[Locrian99]

My gut feeling is that you have a ground layout problem. Here is a link to a video I found very instructive:

https://www.youtube.com/watch?v=lBGE5lwbruE&ab_channel=JohnAudioTech

Hey thanks for the video I suspect this is correct.   Right now I have pretty much the beavis board layout with the cap called for in the schematic, and the input obviously going to the right place.   My power strips are linked at the output end.   I will try and mess with it some later.   Bit confused on how to split the ground signal exactly.   Was thinking run the ground from pins 3 and 4 to one rail and keep all others coming off the other rail?   Will look at some vero layouts and see how those address grounds as the end goal for playing with this is to make it on vero and enclose it.   Was wanting to compare it with the noisy cricket to see which I wanted to do but I suppose with the tranny and ic socketed won't be out much if I just do up two veros. 

[Locrian99]

So I watched a couple videos and found a few more articles on this.   Could get the oscillation completely gone by essentially separating a few grounds to a rail on the breadboard as shown in the video Clint linked. Although interestingly enough if I put that cap he had between pins 6 and 4 it made it worse no matter what I did.   I put it on vero just to see what it would do and I have quite a bit more volume and the distortion is gone with the gain dialed way back.  It's going to work for a test bench amp.   Curious how it sounds through headphones, waiting on an order with the jacks.   I've got some lm386-3s and found some mpf102s as well as j113 to try it in once they get here.   Thanks for all the advice guys.   Kind of wish I would've just put it on vero a bit ago, but feel like I learned a lot through this. 

[Rob Strand]

Could get the oscillation completely gone by essentially separating a few grounds to a rail on the breadboard as shown in the video Clint linked.

The video does a good job showing what needs to be done (and why  ).

Although interestingly enough if I put that cap he had between pins 6 and 4 it made it worse no matter what I did. 

Yes, that's a bit odd.   You might try moving the ground connection side of the cap to be towards the noisy/speaker ground more than the input ground.

If you enclosure is metal and any if more than one of the jacks connect to the enclosure you can get multiple ground connections through the enclosure and that undermines the separate ground scheme (any connectors can do this, audio in, DC power in, speaker output).

Curious how it sounds through headphones, waiting on an order with the jacks.

It should work fine.  Make sure you connect the headphones via a cap not directly to the chip.  You can just connect them to the speaker output.    Slightly better is to put say 33ohm upto 100ohm in series with each headphone line.  What that does is balance the level with different headphones impedances.   With a higher value like 100 ohm you lose a bit more level and you have to judge if that's a too much output drop.

[Locrian99]

Cool.  If I want to use a 12v power supply is there anything special I need to do? 

[anotherjim]

Cool.  If I want to use a 12v power supply is there anything special I need to do?

Depends on the speaker used. you can easily exceed the power rating of the chip. At 12v supply, 16ohm gets up to 1 watt rms? Headphones would be safer WITH the 100R resistors Rob mentioned. Don't want to deafen you.

[Locrian99]

Alright sounds good.  If I use this set up for the headphones just replace that link from the strip with the output from board and speaker out with a 33-100 ohm resistor?