Quiescent current drops when i touch the heatsink

[blu_line]

Only little notice : lead ground line to the geometrical middle between caps - only small unbalance cause hum

[ST: You realy mean that distance, where lead ground attaches, should left and right be equidistance ?
Wow !

Sorry i forgot to upload a component placement or overall layout. I hope you could make any sense of it this way !

grtz

Simon

 

[Upupa Epops]

Hi Simon, can you show, where is speaker ground ?

 

[MikeB]

[ST: You realy mean that distance, where lead ground attaches, should left and right be equidistance ?
Wow !

grtz

Simon

I think, the point is, that the leads have the same length to give
identical resistance. Am i right Pavel ?

Mike

 

[Upupa Epops]

To Simon and Michael : Trough elyts of PS comes from rectifier ripple peaks, which have opposite polarity and " run " also through ground connection. Because ground connection have not zero resistance, only on straigh geometrical middle are both deducted and " disturbance " have zero value. To this point you must connect input ( " signal " ) ground, but also load and all filtration grounds. If you do it by this way, you get quite " silent " amp ( with SNR over 120 dB ) .

 

[blu_line]

can you show, where is speaker ground ?

Somewhere between the caps .

Since this is a prototype i ether connect it on the groundplane or at the power input connector !

grtz


Simon

 

[MikeB]

Hi blu_line !

Any success or new infos already ?

Mike

 

[thanh]

oh! interesting! When i touch the speaker ,my speaker sound "boop, boop,..." .I increase compensate capacitor

 

[blu_line]

Any success or new infos already ?

Sorry Mike. Not yet !
Last week was a very busy one.
Tryo to do it tomorrow.

oh! interesting! When i touch the speaker ,my speaker sound "boop, boop,..." .I increase compensate capacitor

So....... what do you try to say here ?


grtz

Simon

 

[MikeB]

Hi !

Actually, at the moment i also experience some instabilities, will
hopefully fix this...

Thanh !
If touching speakerterminal is audible, the cap in feedbacknetwork
typically is too big, or RC at output is missing ?

Mike

 

[blu_line]

I did some measurements on the amp today, including the fixes from Mike. They did not completely solve the problem.

Grounding the DC servo on a different spot did come a lot closer to quietness. But not entirely.

And then...... i blew it.
Somehow i moved my probe and touched i do not know what.
Damn.


grtz

Simon