MOTM

Hi, me again :-)

Thanks again for all the links and tips about building a cabinet.

One thing I've not seen mentioned (so far) is shielding. Would it be  
necessary to put shielding inside the cabinet to keep out the barage  
of modern hf gadgets? (Cell phones, etc?) I mean, these waves just  
love a good pn-junction, no?

Ben

No, I ve never shielded a cabinet or seen one shielded. At most, you may have to make sure that you don t have a sensitive VCO board hanging right over the

The power input section of MOTM modules uses ferrite beads to filter out 
RFI at the power connector.  And since the patch cords are shielded, 
that eliminates another potential antenna.  I don't recall this being 
too much of a concern.  Never heard of anyone needing to shield a cabinet.

Richard Brewster
http://www.pugix.com

Ben Stuyts wrote:

> Hi, me again :-)
>
> Thanks again for all the links and tips about building a cabinet.
>
> One thing I've not seen mentioned (so far) is shielding. Would it be  
> necessary to put shielding inside the cabinet to keep out the barage  
> of modern hf gadgets? (Cell phones, etc?) I mean, these waves just  
> love a good pn-junction, no?
>
> Ben
>
>
>

I'll chime in even though I'm saying the same thing that's been said:
shielding the cabinet isn't necessary. My modular is in the same room as
half a dozen or so computers and other miscellaneous electronic devices,
including some completely unshielded digital circuits on breadboards, and I
don't seem to have any trouble with it picking up noise.

--Adam

>I'll chime in even though I'm saying the same thing that's been said:
>shielding the cabinet isn't necessary. My modular is in the same room as
>half a dozen or so computers and other miscellaneous electronic devices,
>including some completely unshielded digital circuits on breadboards, and I
>don't seem to have any trouble with it picking up noise.

Oh, your modular is *completely* free of noise? ;-) Of course you 
didn't say that, so consider this:

Wendy Carlos said that building a Faraday cage around her entire 
studio reduced the noise level throughout. She concluded that RFI 
(radio frequency interference) is usually heard as broadband noise. 
So, where there's electrical noise (i.e. everywhere), there may well 
be an RFI issue.

Fortunately, the noise level of good gear is low enough that we 
needn't obsess over this. I'm sure not interested in shielding my 
entire studio room! I'm not even sure how to do it.
--
john

Wendy was using 30-year old equipment.

I have not had the pleasure of looking at a System 55 but I have the
schematics and ferrite beads ain't innem.  Considering that she was also
using a home built mixer and heavily altered Ampex tape decks, I'm betting
that the faraday cage was the most cost-effective way to get rid of the
noise when you look at the cost of dismantling every module and system in a
working studio.  You are also looking at better alloys for signal and power
connector contacts - less chance of rectifying a nearby 50,000 watt AM radio
station.

Dave

> -----Original Message-----
> From: motm@yahoogroups.com [mailto:motm@yahoogroups.com] On 
> Behalf Of John Mahoney
> Sent: Tuesday, September 12, 2006 6:54 PM
> To: 'MOTM litserv'
> Subject: RE: [motm] Cabinet shielding
> 
> 
> 
> >I'll chime in even though I'm saying the same thing that's been said:
> >shielding the cabinet isn't necessary. My modular is in the 
> same room as
> >half a dozen or so computers and other miscellaneous 
> electronic devices,
> >including some completely unshielded digital circuits on 
> breadboards, and I
> >don't seem to have any trouble with it picking up noise.
> 
> Oh, your modular is *completely* free of noise? ;-) Of course you 
> didn't say that, so consider this:
> 
> Wendy Carlos said that building a Faraday cage around her entire 
> studio reduced the noise level throughout. She concluded that RFI 
> (radio frequency interference) is usually heard as broadband noise. 
> So, where there's electrical noise (i.e. everywhere), there may well 
> be an RFI issue.
> 
> Fortunately, the noise level of good gear is low enough that we 
> needn't obsess over this. I'm sure not interested in shielding my 
> entire studio room! I'm not even sure how to do it.
> --
> john
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
>

I haven't attempted to measure the noise floor of my modular. Considering
that my modular consists of 37 modules that can be connected in many, many
different ways, making such a measurement would be sort of silly. I mean, I
could either choose between the output of a single VCO, or the output of the
same VCO fed through a series of seven filters, nine VCAS, and four
Buchla-style low-pass gates. I could choose whether or not to use the output
of a MOTM 830 mixer directly, or I could use the output of my hand-built
balanced-output module which I built specifically to drive long cables
across the room from my modular to my Apogee converters, going past a
computer and its two monitors and half a dozen wall warts.

In any case, my modular is free enough of noise that the noise level is a
non-issue for commercial recordings. As you said, good gear has a low enough
noise level that we needn't obsess about it--until something goes wrong. :-)

I read that Wendy Carlos interview also. I dare say that the S/N ratio in my
studio is at a level she could only dream about with the recording gear she
had at the time. As someone else said, we enjoy the advantages of 30 years
of electronics development. I suppose I could have asked her about Faraday
shielding when I met her at a trade show, but I babbled foolishly about
vocoders instead.

--Adam 

> -----Original Message-----
> From: John Mahoney [mailto:jmahoney@...] 
> Sent: Tuesday, September 12, 2006 7:54 PM
> To: 'MOTM litserv'
> Subject: RE: [motm] Cabinet shielding
> 
> 
> >I'll chime in even though I'm saying the same thing that's been said:
> >shielding the cabinet isn't necessary. My modular is in the 
> same room 
> >as half a dozen or so computers and other miscellaneous electronic 
> >devices, including some completely unshielded digital circuits on 
> >breadboards, and I don't seem to have any trouble with it 
> picking up noise.
> 
> Oh, your modular is *completely* free of noise? ;-) Of course 
> you didn't say that, so consider this:
> 
> Wendy Carlos said that building a Faraday cage around her 
> entire studio reduced the noise level throughout. She 
> concluded that RFI (radio frequency interference) is usually 
> heard as broadband noise. 
> So, where there's electrical noise (i.e. everywhere), there 
> may well be an RFI issue.
> 
> Fortunately, the noise level of good gear is low enough that 
> we needn't obsess over this. I'm sure not interested in 
> shielding my entire studio room! I'm not even sure how to do it.
> --
> john
> 
> 
> 
>  
> Yahoo! Groups Links
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
>

Hi Moe, and all others that have replied,

On 12 Sep 2006, at 17:54, Dave Bradley wrote:

> No, I've never shielded a cabinet or seen one shielded.

Ok, that seems to be the general consensus here. Good to know.

> At most, you may have to make sure that you don't have a sensitive  
> VCO board hanging right over the power transformer.

Makes sense.

There's a big antenna of a local police station visible from my home  
studio. Never had any problems with interference, and I've measured  
the field strength once with a borrowed meter. It was below 0.3 V/m  
across all frequencies. (My cell phone up close produces more noise...)

Thanks,
Ben

>One thing I've not seen mentioned (so far) is shielding. Would it be 
>necessary to put shielding inside the cabinet to keep out the barage 
>of modern hf gadgets? (Cell phones, etc?) I mean, these waves just
>love a good pn-junction, no?

I don't think it's necessary. Sure you might be able to measure lower 
noise if you built your studio inside a Faraday cage, but that would 
be overkill.

In my studio I can't use any unshielded wires otherwise I can hear 
all kinds of RF hash and any dimmer switches that I haven't already 
yanked out (banana jacks are officially banned in my studio). Yet 
even switching to balanced lines makes no audible difference with 
regards to RF hash. Simply using shielded cables eliminates it 
entirely. I've had no need to even consider shielding the insides of 
my cabinets.

>I have to disconnect my home wireless telephone to make a recording.

I've been wondering about Wi-Fi as well.  Tends to all be in the 2-6GHz 
range.

The worst offenders for RFI are cell phones.  Those are nasty little 
creatures.  They put out all sorts of broadband garbage and tend to 
induce noise directly into some gear, even without cabling issues.

Ivan

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On Sep 12, 2006, at 9:57 PM, Dave Halliday wrote:

> Wendy was using 30-year old equipment.
>

The other thing is, as I recall, her studio was in Manhattan.  Which is
probably one of the worst RFI environments in the world.  And in her  
day,
power there wasn't very good either.