To earth, or not to earth...

Paul Schreiber synth1 at
Sat Nov 29 23:02:53 CET 1997

The trouble with using banana (EVEN Serge) is that you are relying on a ground loop (Bad!) for your
audio signals. This will allow 50/60Hz hum to enter the system. The "convience" of stacking can easily be
gotten around by multiples.

The problem with 1/4" is that the holes are large enough for dust to get in. Also, the cost of the interconnect can be expensive.

I think 3.5mm" jacks are a good compromise. You can get molded, sheilded cables pretty cheaply from Mouser.
They are not as rugged (ie sustain a zillion plug/unplug cycles) as either banana or 1/4". 

Actually, the best choice is BNC. These are the 1/4 turn connectors found on test equipment (ie scopes). They
are sealed against dust, cost the same as a good Switchcraft 1/4" jack, and you can swing a Moog 55 over your
head with one patchcord (not recommended, see Page 47 of the Owner's Manual). The downside is the
relative cost of the cables, about 20% over 1/4". But for sheilding and reliability you can't beat them.

MOTM will have holes for 3.5mm spaced far enough apart to allow other jacks to be used if you drill them.

Paul Schreiber
Synthesis Technology

From: 	Alex Noble[SMTP:alex at]
Sent: 	Sunday, November 30, 1997 12:11 AM
To: 	synth-diy at
Subject: 	To earth, or not to earth...

I'm currently building up stocks of bits and bobs to aid me in my quest
build myself a bit of a modular synthesisor, and I've seen all the
discussions about the different patch methods (banana/jack), but since
I'm not too surea bout myself at this point, what great difference does
the earth conenction make in this respect? I mean, what benefit does a
earthable mono jack plug have over the standard single-wire banana plug?
What is a normalised connection? Doesn't this cause problems with earth
loops and hum and all that palarver?

Oh aye, somebody thoughtfully unsubscribed me a week or two ago, so I'm
not sure what the conclusion of the small scope thread was. If nobody
mentioned it before, Maplin sell a mini size (95mm diagonal screen) CRT
monitor unit for a hundred squids. Needs a 1v pk-to-ok vid source, 2
pots for brightness and contrast and a +12v DC 400mA ps. 203x36x103mm.

Any help?

Also, any news of the motm scheme? What size/type of patching does the
digisound gang use?

Alex Noble.........................................alex at
  Wicked original music for your ears:
                     Home of Euphy Scott Productions.

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