THRU
Someday you’ll do a show at Carnegie Hall and realize that one M•1200 or M•1400 ampli- fier is just not going to do the job — you’ll need a
A general rule of thumb is to
maintain a load impedance
10 times or more than the
source impedance to prevent
excessive loading. If your console has an output impedance of 100 ohms, then you can
The THRU jacks can also be used to relay the signal on to other devices such as a DAT or cassette recorder, enabling you to record ex- actly what the audience is hearing. The THRU jacks are wired straight from the XLR and TRS INPUTs — there is no electronic circuitry between — so the signal going into the amp is exactly the same as the signal coming out of the THRU jacks.
You can use the THRU jack
as an input, if necessary,
since it’s wired in parallel
with the other input connec- tors. You can also use the
1/4" TRS INPUT jacks as THRU jacks. Simply connect the 1/4" TRS INPUT jacks on the first amplifier to the TRS 1/4" INPUT jacks on the second amplifier using
Warning: If you use a regular guitar cord with
(–)of the signal (pin 3).
LOW CUT FILTER
Every woofer has frequency response speci- fications. It’s usually expressed in Hertz (or cycles per second), like
can’t reproduce — you can’t hear it, and worse yet, it’s a waste of amplifier power that can be better used reproducing frequencies you can hear.
5dB
0dB
1Hz | 10Hz | 100Hz | 1kHz | 10kHz 20kHz |
Low Cut Filter Frequency Response
In order to match the output bandwidth with your particular speaker system, the M•1200/M•1400 amplifier has a tunable LOW CUT FILTER. The frequencies are clearly marked along the knob’s travel :
•Fully counterclockwise, the frequency is below 10Hz, effectively bypassing the filter.
•Center detent is 35Hz and labeled TYPICAL, since precious few woofers actually go below that.
•3/4 of the way up is labeled STAGE MONI- TOR, 100Hz, perfect for, well, stage monitors (they seldom reproduce below 100Hz; besides, it prevents
•Fully clockwise is labeled 170Hz.
So, grab your woofer’s spec sheet and find the low
If you do this correctly (and make sure the meters are happy), you’ll never again see your woofer moving sporadically without au- dible signal. Your system will play louder and cleaner, and you may never blow another woofer again!
CONSTANT DIRECTIVITY
Compression drivers mounted on constant- directivity horns require compensation, in the form of a
Until now, you’d have to resort to external crossovers or worse yet, graphic EQ modules. Both of these are fraught with limitations, not to mention adding cost, rack space require- ments and complexity to your system.
The M•1200/M•1400 Power Amplifiers eliminate the need for any of these external devices — they have the compensation cir- cuitry already built in. And using it is a breeze.
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