Jared's correct, the Line In is balanced.
Jack also wrote:
"On more thing I found that has me quite perplexed:
On the back of my Valley people rack it says balance in, unbalanced out.
I have no idea why they did it that way but the really weird part is
that the terminals are marked +and- on one and ground on the other. You
just confirmed that the - or common should be tied to the ground not the
positive."
To address this and the Valley People question: It is very common
to have devices with "active" balanced inputs (as opposed to transformer
balanced inputs) and UN-BALANCED outputs. A few pieces of gear with this
arrangement that you may have heard of? The original dbx-160VU and it's
kin, Sontec and ITI equalizers, GML eq's and compressors, Klark-Teknik
DN-360 eq's (without the optional transformers)...the list goes on.
There are literally tens of thousands of pieces of pro gear out there
with that arrangement. Why? With the advent of op-amp modules, and then
low priced IC's, it suddenly became very cheap to build a differentially
balanced input stage...all you need is one chip, or one section of a
dual or quad chip, a few precision resistors and a few caps. An actively
balanced output, on the other hand is a lot more complicated, requires
more parts, often needs to be trimmed in final assembly (to get the +/-
o/p's matched) and often involved compromises and trade-offs in how they
were able to cope with driving an un-balanced input (ProTools HD being
the best current example...they want you to NOT terminate the (-) side
when driving an un-balanced load).
As far as wiring the Valley People output: Use a balanced (ie. 2
conductor +shield) cable, but put separate spade lugs on the (-) and
Shield leads. Put both spade lugs on the "ground" terminal. If you get
noise, try lifting the shield lead. If you don't, leave it alone.
And finally, does anyone else here remember Craig Anderton's column
in Modern Recording magazine? His advise was always "just plug it in and
see what happens...you're not going to break anything if you get it
wrong" (or words to that effect...obviously this doesn't apply to
anything to do with power amps).
best,
Ike
On 9/9/2010 1:45 AM, Jack Dean Stauss wrote:
I will verify that aspect while the console is still pulled apart.
Thanx for the tip, I hope you are right, it will save some time.
Jack
Sent from my iPhone
On Sep 8, 2010, at 9:25 PM, Jared <[email protected]
<mailto:[email protected]>> wrote:
Hi Jack
A side note:
Are you sure your line ins are unbalanced? A lot of series ones have
balanced inputs and unbalanced outputs. At least that is how mine are.
I thought I would mention this since it might save you a headache later
take care,
Jared
-----Original Message-----
From: "[email protected] <mailto:[email protected]>"
Sent: Sep 8, 2010 4:36 PM
To: [email protected] <mailto:[email protected]>
Subject: NEOTEK: Patch Bay Question
I seem to remember getting a lot of useful information from this
list the last time I addressed my unbalanced/balanced patch bay
issues so I was hoping someone here could answer a couple
questions I have along those same lines:
My patch bay and snakes are balanced and typically to convert the
1/4 connectors on the ends of the snakes that feed the patch pay
you just get new unbalanced connectors AND tie the common and
ground/shield together.
I will be plugging these snakes in to my unbalanced Series One
for it's direct outs, line ins etc and I wanted to make sure this
was an acceptable approach, have any of you tried this before?
I do not need to rewire to an unbalanced patch bay do I?
Thanx,
Jack
Jack Dean Stauss
No Static Pro Audio, Inc.
3083 N. California St.
Burbank Ca. 91504
818-729-8554
818-729-8551 Fax
www.nostaticav.com <http://www.nostaticav.com>
[email protected] <mailto:[email protected]>
--
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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