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Getting started... a MUST Read !
a) CONSUMER SOURCE EQUIPMENT
The ARC-15 console is designed to be used with balanced professional & unbalanced consumer type audio source equipment such as CD players,
MDs, DAT machines, cassette machines, etc. Unbalanced consumer equipment is designed to perform well in compact studios where audio cables
are short. Balanced audio is required when connecting multiple studios or with long audio cable runs ( > 10 feet). When choosing consumer audio
equipment, choose equipment that has 2 prong AC power plugs (not the 3 prong plugs).
b) AC POWER CONSIDERATIONS
Plug all of the equipment in your studio into a single AC power strip!
Unbalanced consumer source equipment is not designed to reject AC power line hum. This makes it important to put ALL of the equipment
in the studio on the same branch of the AC power and preferably on a single AC power outlet. A single power outlet will have a 1500-2000 watt
capacity. That is plenty of power for most studios. Simply plug a multi-outlet AC power strip into the single wall outlet and then all of your equip-
ment into the power strip. If possible, the power strip should be the kind that has internal surge protection.
Because many buildings have as many as 8-12 duplex wall outlets on a single 1500-2000 watt branch, you must have NO other equipment
on any of those 8-12 other outlets. Make sure the branch your outlet is on does not also power the lights or any other building equipment.
c) SOME THOUGHTS ABOUT 60 CYCLE HUM (or some ideas about what to do if you get it)
The RCA audio cables used in consumer audio equipment connect the chassis ground and signal ground of all of the equipment in the studio togeth-
er through the cable shield. All shield ground connections should be as tight and low impedance as possible. Use only high quality RCA (IHF) audio
cables.
Most consumer audio equipment will have a 2 prong AC power plug. Some equipment has a 3 prong AC power plug. The third prong on a 3
prong plug is a "Safety Ground" which grounds the chassis to reduce shock hazard. The 3rd prong must never be removed even though it creates
a 2nd ground path along with the audio cable shield ground. Two ground paths creates a "Ground loop" antenna which picks up 60 cycle AC hum. If
possible, use only equipment that has 2 prong AC power plugs. With stubborn hum, replace the equipment with 3 prong AC power plugs with equip-
ment with 2 prong AC power plugs. This is often less expensive that making a custom audio cable with audio transformer isolation.
If there is NO other ground connected to the studio, a single piece of equipment with a 3 prong AC plug does not create a ground loop.
However, if there is another ground (such as from another studio) or a 2nd piece of equipment with a 3 prong AC power plug, then a ground loop is
completed. If you can not change to two prong equipment, it may be necessary to use an audio isolation transformer on the audio cable to break
the audio ground path. Contact a technician or the factory on how to build a transformer isolated audio cable.
In some stubborn cases of hum (or RF interference), the best solution is to make the ground resistance between ALL of the equipment
as low as possible. To do this, connect all of the equipment chassis' together with #12 stranded, insulated wire. Each piece of equipment is to have
its own wire that returns in a star configuration to a single point in the studio. That single point should return by a single ground wire back to the
main station ground. A 2"-4" copper ground strap to station ground is best.
d) CONNECTING MULTIPLE STUDIOS
When connecting multiple studios, long audio cables are sometimes necessary. These long cables can introduce AC hum into your audio. In these
cases, it may be necessary to use distribution amplifiers with balanced inputs and outputs (or audio isolation transformers) to break the ground
path and to cancel the AC hum.
e) STEP BY STEP INSTALLATION PROCEDURE
When building a studio, it is important to be able to isolate problems that may be causing noise, hum, or even not passing audio. To do this properly,
the studio should be assembled and tested one piece of equipment at a time. Each problem is detected and eliminated as it occurs. This manual
provides a basic step by step process to assemble and test your studio.
I N S T A L L A T I O N I N S T R U C T I O N S
4.3
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