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-   -   F5 - is normal ICs twist out the Hum? (http://www.diyaudio.com/forums/pass-labs/224531-f5-normal-ics-twist-out-hum.html)

Blink_PT 28th November 2012 08:07 PM

F5 - is normal ICs twist out the Hum?
 
I know much has been written about the hum, but I have done all, the last thing I did was twist the cables and ICs hum almost disappears! It remains a bit, but this is no solution.

No longer know what to do, is a small hum, touching the ear to the speaker is quite perceptible.

I made a star as the image is, the masses of the left channel and right channel bind to this connects to a central point, this point connects to the mass of the PSU.

I have the source with 8 capacitors 15,000 each, had bought a pack of 10, 2 left over, I'd better turn over these 2 who are outside? Where would be best to connect the PSU? One for each channel at the entrance of the source at 2.2 K?

http://img208.imageshack.us/img208/2540/f5meu.jpg

http://img145.imageshack.us/img145/6555/f5hum6.jpg

http://img854.imageshack.us/img854/578/f5hum2.jpg

http://img201.imageshack.us/img201/3094/f5hum1.jpg

http://img189.imageshack.us/img189/900/f5hum3.jpg

http://img27.imageshack.us/img27/691/f5hum4.jpg

http://img689.imageshack.us/img689/658/f5hum5.jpg

I made a star as the image is, the masses of the left channel and right channel bind to this connects to a central point, this point connects to the mass of the PSU.

http://img13.imageshack.us/img13/4530/f5hum7.jpg

richie00boy 28th November 2012 08:32 PM

Do not connect the ground between the two input sockets. The amp 2 socket should have its ground back to the gnd track on amp 2, just like you did for amp 1.

Zen Mod 28th November 2012 10:42 PM

1 Attachment(s)
make like this , but without red bridge fat wire

if small hum residue , put red bridge fat wire directly and in shortest way , between two pcbs (grounds)

Blink_PT 29th November 2012 01:15 AM

Quote:

Originally Posted by Zen Mod (Post 3261515)
make like this , but without red bridge fat wire

if small hum residue , put red bridge fat wire directly and in shortest way , between two pcbs (grounds)


Thanks Zen Mod, did your scheme but was more hum.

Tomorrow I will turn the bridge with such large wire and see if that solves the problem ...

dazed2 29th November 2012 02:35 AM

I used to have hum too until I configured it like so:
No input ground from RCA's to the amp boards at all.
RCA hot to amp board, the Hot to the speaker, and the V+ and V- from the power supply. No ground at all on the amp board.
The RCA ground and speaker return I have connected to the PSU board ground then through the thermistor then chassis. AC ground is connected at the same point to the chassis as well.

Blink_PT 29th November 2012 09:38 AM

Quote:

Originally Posted by dazed2 (Post 3261831)
I used to have hum too until I configured it like so:
No input ground from RCA's to the amp boards at all.
RCA hot to amp board, the Hot to the speaker, and the V+ and V- from the power supply. No ground at all on the amp board.
The RCA ground and speaker return I have connected to the PSU board ground then through the thermistor then chassis. AC ground is connected at the same point to the chassis as well.


Do not quite understand what she said!.

A scheme would be excellent. thank you

Zen Mod 29th November 2012 10:19 AM

Quote:

Originally Posted by Blink_PT (Post 3261722)
Thanks Zen Mod, did your scheme but was more hum.

Tomorrow I will turn the bridge with such large wire and see if that solves the problem ...

you have pots on sch , but I can't see them on pictures ?

Murdoc 29th November 2012 10:36 AM

Hi!
This helped me to get my whole system hum free but also I learned why: http://www.diyaudio.com/forums/diyau...onnection.html
It's a bit longer read than staring to a picture, but it pays off!

(I even don't need the CL60 or diode bridge!)

Or look here and while you're listending to hum free music, read the above. ;) AlephWiki : Anschlussplan
Lautsprecher = speaker
zentraler Massepunkt = Star Ground

Kind regards
Matthias

flatheadmurre 29th November 2012 11:12 AM

Depending on how good the transformer is try shielding the input wire.

In my F5 i have a toroid of unknown origin and without shielded input cables it hums !

Blink_PT 29th November 2012 11:26 AM

Quote:

Originally Posted by Zen Mod (Post 3262260)
you have pots on sch , but I can't see them on pictures ?

Yes, I use pots Vishay Spectrol...


http://img443.imageshack.us/img443/2/potsy.jpg


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