Hi
Yes, a noisy op amp can work pretty well. I presume you are trying it on
any ' osc out' connection and routed to busses (slate) route.
On the assumption that the noise is from one place and gets into several
others it is correct that it's level will increase as it will add. 2
'routes' will increase the level by 6dB, 4 routes by 12dB and so on. If
the noise were getting into 32 channels 'coherently' then it would be
greater by about 30dB so what may appear to be 'small' noise when
listening to 1 channel, by the time it is summed with many it can be
very noisy indeed. This is the reason that mix busses must be REALLY
clean as coherent noise (hum pickup for example) can be magnified by
tens of dB.
Matt S
On 19/07/2011 13:25, [email protected] wrote:
Could the osc. make the noise and still operate correctly?, it's working.
doug
------------------------------------------------------------------------
*From: *"Ike Zimbel" <[email protected]>
*To: *[email protected]
*Sent: *Monday, July 18, 2011 4:09:59 PM
*Subject: *Re: NEOTEK: aux noise
Hi Doug,
Following on Matt's suggestions, I would agree that the oscillator
section could be suspect. I would also check that all of the logic chips
are well seated and that their leads and sockets look good. Replace them
if they don't. Also make sure that all of the ground connections,
including mechanical connections to the front panel (pots, switches
etc.) are clean and tight. It is unlikely that the Aux sends are
creating this noise, but more likely they are amplifying noise that's
coming from something common to them, again as Matt said. I am away from
the shop for a couple of weeks so I don't have access to my Elan
drawings to give you specific chip names, locations etc.
Best,
Ike
On 11-07-18 8:54 AM, Matt Syson wrote:
> Hi
> You are looking for something 'common' as it adds up when listening to
> more stuff on Solo.
> It could be supply noise (check with an oscilloscope) or a module
> which is seriously noisy or even talkback or slate tone circuitry that
> has access to aux busses although may be nominally 'switched off'.
> Double check all possible outputs and look for any 'common' circuitry
> (the 'block diagram' should get you close). Ultimately, pull modules
> or 'break up' the mix bussing if it is available on plugs.
> Matt S
>
> On 18/07/2011 13:35, [email protected]
> <mailto:[email protected]> wrote:
>>
>>
>> Hello, I think this is the way to post here.
>>
>>
>> I have a 15 year old 40 channel Elan I bought new. It's been very
>> reliable. It was in a fire 7 years ago. I got it back in commission
>> after a couple of idle years of storage and cleaning/repairing. It
>> was recommissioned and has done pretty well, everything works except
>> some partially working l.e.d. meters.
>>
>> Lately the master section has a small ripply sound when cranked all
>> the way up without channels turned on. Small annoyance, but
>> irritating. However when you solo the auxes you get a really intense
>> version of hiss noise ripply trash, sounds like a combination of
>> computer interference meets bad caps/junk. As I said it's appeared of
>> the last few months. Soloing A,B,1,2,3,4, just adds to the crap
>> incrementally. When using the track busses to pro tools, it's fine ,
>> goes to pro tools good and quietly.
>>
>> I recently tested and or replaced all the resistors in the power
>> supply and recapped the power supply. I also disconnected the Elcos
>> for everthing except the monitor one to the amps to make sure it
>> wasn't from another piece of gear.
>> I still have the trashy sound in auxes. Any suggestions? Any logical
>> procedure to locate the source of my noise?
>>
>> thanks , doug
--
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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