There is already a F5-turbo thread: http://www.diyaudio.com/forums/pass-labs/206240-f5-turbo-posted.html#post2896796
I think:
Post all F-5 Turbo stuff here:
http://www.diyaudio.com/forums/pass-labs/206240-f5-turbo-posted.html
and
F-5 Turbo Circuit Board designs here:
http://www.diyaudio.com/forums/pass-labs/206756-f5-turbo-circuit-boards.html
General F-5 stuff should continue here..
Post all F-5 Turbo stuff here:
http://www.diyaudio.com/forums/pass-labs/206240-f5-turbo-posted.html
and
F-5 Turbo Circuit Board designs here:
http://www.diyaudio.com/forums/pass-labs/206756-f5-turbo-circuit-boards.html
General F-5 stuff should continue here..
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Having a low thermal stability is important; that should make the brand decision;
25 turns is enough for the 500 ohms - you stay within about 4 turns anyway.
Well I don't think it's a PS issue at this point... Pulled one of the input cables out accidentally when I was troubleshooting, and the noise vanished... So, with either channel connected and the other disconnected, quiet as a church mouse, both channels connected, the buzz is back. It's not much, but enough to be noticeable with my 105dB/w horns. I don't think it can be a ground loop, even does it when connected to a battery powered JBOZ that's not connected to anything that's grounded...
Any ideas?
Roscoe
Hi Roscoe,
did you solve your problem?
I have exactly the same problem with my new F5.
When the 2nd cinch cable is connected, i have a light deep hum in my horns (107dB/w).
*Had* the same symptoms. Have grey hair to prove it...Hi Roscoe,
did you solve your problem?
I have exactly the same problem with my new F5.
When the 2nd cinch cable is connected, i have a light deep hum in my horns (107dB/w).
Re-routed the PCB power, In and Out 0-volt wiring to a proper star-ground point. Made sure all "symmetric" cables are of the same/similar length. Problem gone.
Other things to try
- a small polyprop cap (2.2uF) across the rails (parallel with the last bank of the PSU caps).
- use proper shielded cable for In (but connect only ONE side of the shield to 0-volt!).
As a matter of interest, with In plugs shortened, what is the AC offset that you get on the output? (it's not the DC offset that you hear as hum)
All cables are symmetrical build. You could have a look in my blog for that.
If i short the right channel, the hum vanished...
The AC offset with connected cables (hum) is 4,2mV. When the right channel is shortened, AC = 0.
I have switched the pre amp to my audionet with 1m Nordost Tyr
and made a quick star ground modification to my psu pcb:
The result:
Still a small hum in both speakers, when both interconnects are connected.
It vanished only when i short the right input...
Did anyone have additional ideas?
and made a quick star ground modification to my psu pcb:
An externally hosted image should be here but it was not working when we last tested it.
The result:
Still a small hum in both speakers, when both interconnects are connected.
It vanished only when i short the right input...
Did anyone have additional ideas?
If it were so simple... I try to find the problem now for 3 days...
It is curious that it vanished only when i short the right input.
I disassembled the right amp pcb today to check all solder points, but everything is ok.
Very interested in the out come here, I'm sure several out there would like the few more dB of gain, and are just too chicken to jump, like myself! In the Turbo F-5 article, Mr Pass talks about this and changes some resistors to increase gain, would these same changes work with the standard F-5, or are they particular to the Turbo version in the article? My reading seem to make me feel this would be fine, but you could fill a battleship with what I dont know here!
Thanks,
Russellc