Hi Ike, Matt and Monte,
Thanks so much for the input. Lots of ideas there. Believe me, right about
now I can use them so it's very much appreciated. No days off here until the
week after next so I'll be doing a bit each night post session. I'm
preparing myself for a slow and frustrating hunt on this one. Sounds like I
was vaguely on the right track at least.
To respond to Ike's questions:
-Do you only hear the noise when a solo is engaged?
Yes.
-Does the noise print to the 2-mix?
No, but the noise floor of the master left bus does read a little higher on
our DAW meters, but this noise is not audible in the way the solo circuit
noise is (eg with the the master fader up the noise floor for the left
master bus reads 5-10db higher than the right down at -90 odd.. The DAW
meters also show extraneous noise on the left master bus when the impedance
of the master fader changes (up or down), and the settling time is a lot
slower than the right side.
-Are the monitors clean with another source selected?
Yes. This is only a problem when solo is engaged except for the convoluted
routing problem mentioned below.
You might also try removing U-4 on the Monitor module altogether. If
the noise is still present, but at a reduced level, than as Matt
suggested, it may be coming from a channel module. If the noise is the
same level, that would point to Q-103, the Left Solo switching FET.
With U-4 removed there is silence on the circuit.
Q103 has already been changed out, as have Q101, Q102, 104, Q115, Q118 &
Q119.
Matt's last email has triggered my memory with regard to mentioning hum. We
recently attempted some mixing to stems out the first 16 busses, summing in
the box and bringing the DAW 2-mix back into the control room extra input.
This created ground loop issues but for the first hour or so there was also
a god awful hum when monitoring the return to the control room extra input.
(sounded like a ground was missing and a lot like transformer hum). It
slowly dissappeared. Tightening all the screws on the power supplies, the
ground bus, individual module screws and cleaning the bucket frame and the
underside of the modules had no effect.
I'm starting to see a pattern. Could this hum be a product of the same short
and also be an indicator that the short isn't necessarily close to the solo
amps?
Thanks again all, I learnt a lot from those few emails. I'll come back after
I've done a bit of prodding.
Brent Punshon
Head Gap
Melbourne, Australia
Ph:+613 9480 6280
www.headgap.com.au
------
View the list online at: http://www.mail-archive.com/[email protected]
You can unsubscribe at anytime by sending an email to mailto:[email protected] with
"unsubscribe neotek" in the message body. If you have any difficulties, or
questions --please send an email to mailto:[email protected].
The Neotek list is lovingly hosted by Catapult Web. Remember that any message
or reply sent to the list will be automatically forwarded to all subscribers.
Vive Le Neotek!
Thanks.
