Rane SAC 23 User Manual download pdf (Page 6)

Manual-4

Mid range

Amplitude (dB)

100 Hz Filter

Frequency (Hz)

Low passSub High pass

Low/MidMid/High

Crossover Philosophy

Now it gets real fun. e idea is to set the output LEVEL

controls on the crossover so that the entire speaker system has

a uniform, ﬂat response. Unfortunately, the room in which the

speakers are placed has a habit of always getting into the act, so

things get messy. As a result there seems to be two schools of

thought regarding the use of active crossovers.

The Set‑lt‑Once‑And‑Glue‑lt School

e philosophy here is to use the crossover to ﬂatten system re-

sponse as much as possible without room acoustics involved. is

means setting up the system outside (unless you happen to have

a very large anechoic chamber handy) and with the aid of a real-

time analyzer and pink noise source, adjust all of the crossover

outputs so that the system is as ﬂat as possible. Once the system

is tuned, the crossover is then locked behind a security cover

(posted guard is optional) and never again touched. It is then the

job of the system equalizer(s) to normalize or ﬂatten the response

for each diﬀerent room.

The Fix‑lt‑With‑The‑Crossover School

Here the crossover knobs get a good workout, for the crossover

is used at each location to help ﬂatten the system along with the

equalizer.

Regardless of which school you profess, the absolute impor-

tance and eﬀectiveness of some kind of realtime analyzer in your

system cannot be overstressed! An analyzer saves tremendous

amounts of time and provides the absolute consistency, accuracy,

and plain old good sound that very few ears on this earth can

deliver. ey are aﬀordable, easy to use and amazingly eﬀective.

You owe it to yourself and your audience to at least look into one

of today’s cost-eﬀective analyzers—you’ll wonder how you man-

aged at all without one.

OPERATING INSTRUCTIONS

Selecting Crossover Frequencies

Most speaker manufacturers supply low and/or high frequency

cut-oﬀ points for each driver, especially if these are supplied in

a system. ese cut-oﬀ frequencies are based on each driver’s

performance, with a certain safety margin to accommodate more

gentle ﬁlter roll-oﬀs.

e SAC 23 utilizes 31-position precision DC control voltage

potentiometers to select the frequency points. is crossover

design assures consistent accuracy from channel-to-channel and

unit-to-unit. is is a distinct advantage over continuously vari-

able designs using ganged potentiometers which can yield large

variations in channel-to-channel matching. Even with 31 choices

it is possible that the exact recommended crossover frequency

may not fall on one of the selector detents. Not to panic, for

drivers have their own gradual rolloﬀs and tolerance variations.

Just pick the closest one. When in doubt, choose the higher

frequency setting.

For best overall system results, try to choose the speaker

components so that each operates well within its recommended

limits. is provides valuable leeway so that crossover points

may be adjusted in order to ﬁne-tune the system. is also yields

higher system reliability. If at all possible, always use some kind

of realtime analyzer to tune your crossover, and then ﬁne-tune

each system with an equalizer. Keep reading for further align-

ment details.

Setting the Output Level Controls

e INPUT LEVEL is an overall system sensitivity adjustment.

Use this control to decrease the overall sensitivity of the entire

sound system, including the mono subwoofer if you are using

one. You will generally want to start with this control in the full

clockwise (or “10”) position.

e LOW, MID, HIGH, and MONO SUB OUTPUT

LEVEL controls allow you to compensate for sensitivity varia-

tions in ampliﬁers and drivers. Do not use these to adjust overall

system sensitivity unless you plan to re-align the system after-

ward. With these set to the 0 dB mark and the INPUT LEVEL

set to 10, the crossover yields no level change from input to

output. is is the best gain structure and provides the best

signal-to-noise performance.

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Rane SAC 23 User Manual Page 6

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