Hi Brian and Matt,
Brian, for the record, I believe that console you are talking
about was an Elan. Matt, the "Neotek Sound" that I am familiar with
definitely does NOT include power and ground hum. As I mentioned
earlier, I have heard about Neotek consoles having noise problems but
none of the consoles that I have been involved with over the past 20+
years (close to 350 channels of Elite, ELite II, Elan and Series II)
have exhibited the problem that Barak is talking about, nor the problem
and fix that Brian has described here. Most of the consoles that I have
dealt with have an un-weighted noise floor below -82.00dbu, with one
Elite II that I have done a lot of upgrades on hovering around
-90.00dbu. Having said that, when I look at an FFT of the noise spectrum
on those consoles, the dominant frequencies are 60, 120 and 180hz. So,
the consoles are definitely _/susceptible/_ to power and grounding noise
issues.
But, my point here is that in spite of "doing everything wrong",
the consoles are usually quiet, and therefore what Barak is dealing
with, and what Brian described should be treated as anomalies, that
should be solvable. In the case of the Elan that Brian mentions, it is
clearly something that went wrong in the manufacturing process. Like
what? We may never know, but maybe a bonehead mistake like getting the
shield and Tip or Ring mixed up in some signal runs to and from the
patch bay...like the 2-mix insert. Sometimes these things are very hard
to find. 30 years ago I was the production manager for a company that
made lighting consoles here in Toronto. There was ONE factory defective
desk that we built, out of about 100+ units, (which, ironically ended up
being purchased by my very own brother...) The console worked perfectly
and passed all of its pre-delivery tests. Once out the shop door,
however, it started having problems with "ghosting" in the dimmers it
was connected to. I looked the thing over on site and never could find
the problem. Eventually the desk was traded in, and, sometime after I
had left the company, underwent some sort of re-build (I think a
"stretch" to add more channels). During the course of this work, an
un-used centre-tap wire on the power transformer was found crushed
between the base of the transformer and the chassis. This was leaking
half of the secondary voltage onto the chassis, upsetting the DC ground
that the dimming circuits referenced, causing the dimmers to "ghost". So
parts get put in wrong, connections are mis-wired, wires get pinched etc.
In the case of Barak's console, there are still some questions that
need to be answered. In particular, Barak, did you ever own this console
when it wasn't exhibiting this problem?
I have a few more thoughts on this but, I will save them for another
post...or two.
best,
Ike
On 1/29/2010 6:02 AM, Matt Syson wrote:
Hi
I have to say that my experience of Neotek's is limited to a series 1
(in the flesh) but the wiring and particularly grounding, appalled me,
having spent 30 or more years un humming desks for several manufacturers.
There may be a 'following' for the 'Neotek sound' but there are so
many fundamental 'wrongs' going on.
Metalwork, DC power ground and 'mix bus reference ground should all be
separate until intentionally joined at one defined point, not
scattered randomly around the chassis.
Having to fiddle inside the supply to 'null' the hum from there
suggests very poor layout and wiring practice.
The 'sound' may be great but you have to work for it and try to
preserve it against interference from multiple sources.
Matt S
Brian Roth wrote:
Hello Ike, et al:
I recall a new Neotek desk that was delivered here in OKC... 20+
years ago. I cannot recall if it was an Elan or Elite.
From DAY ONE it had "hum issues" on every bus. As I worked with it,
I was shocked to discover the grounding system, which was "every
ground was connected to every ground", including random connections
to the metal work on the front panels.
This was a NEW desk from Chicago.
Audio ground returns were randomly connected to the front panel metal.
I quickly tested the desk with a battery=powered power amp/speaker
combo in order to eliminate any wiring probs, with no I/O besides my
battery-powered system, and at other times my iso'ed scope.
It still hummed/buzzed. Many other tests done..including one
oddity...as I "unscrewed" modules from the frame, the noise changed.
Desk's owner yelled and cried at "Chicago", with no replies for
months. Desk owner SCREAMED, and finally had a reply apparently
from the "unknown mystery circuit designer"...
Solution? Install six or eight feet of 18 or 16 GA wiring INSIDE of
the PS-3 (??) PSU box in series with the "ground return" wiring, and
then fuck with the positioning of that series "wads of wire" inside
of the PSU to "null" the noise.
That came directly from "Chicago".
Egads.....
Best,
Bri
Ike wrote:
Hi Jim, Matt, Barak,
The Elite is different from the Series boards in that the
motherboard is only the width of the master section - 4 modules. The
channel modules buss thru 4 x 16 way .100 ribbon cables and 8 x 3
way .156 Molex headers to the patchbay, fader and meter. So pulling
modules is a bit more complicated. However it is not hard to
disconnect one or both sides of the desk in one go by pulling the
.100 headers from the bottom of the motherboard.
Fitting the master modules in the motherboard is a pain and
has been the topic of another recent thread.
Barak, have you done anything with the master
modules? Another thing you could try is to remove the FX return and
Aux master modules (desk will run without them) so you can see how
the stereo master module is fitting in the motherboard. There may be
some Molex pins bent, missing or not making proper contact. Try
pushing up on the motherboard and see if the hum changes or goes
away. Also check to see if the ground strap is bolted to the bottom
of the mother board.
Best
Ike
--
Ike Zimbel
Zimbel Audio Productions Ltd.
Toronto
416-720-0887
"Studio House Calls". Authorized Warranty service for Allen& Heath, Clear-Com,
Drawmer, Soundcraft, SPL and Yamaha. Repairs and upgrades to analog audio equipment
including: AMEK, dbx, Neve, Neotek, MCI, Soundcraft and more. Ask about our RF Frequency
co-ordination services!
www.zimbelaudio.com
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