Semi-Bi-Amp?

I want to buy two subwoofers, one for each channel;

Main Speakers, a pair of Mirage M490is with 48hz to 22Khz response;

Subwoofer specification:-
Speaker: 12 inch with new CMS (Control Mass Suspension) technology speaker cone with high speed rubber suspension
Voice coil: 2 inch high power flat wire voice coil
Magnet Weight: 60 oz
Amplifier: 350 watt
Frequency response: 25Hz to 160 Hz
Electronic crossover: Double 12 dB/oct Butterworth cascade, , adjustable from 40Hz to 160 Hz
Phase correction: Adjustable from 0 to 180 degrees
Inputs: Line level and Hi-level (speakers)
Outputs: Hi-pass, filtered speaker level, 85 Hz, 6 dB/ octave
Enclosure type: Bass reflex loaded with aerodynamic vent
Finish: Black ash vinyl
Dimensions: Width : 15¾ in. x Depth : 14 7/8 in. x Height : 20 3/8 in.
Net weight: 55 pounds ; not too expensive around $300cdn each:)


What I want is to use my JLH mono to power the Mirage speakers as is, but I want to limit the low frequency input that feed the JLH( nothing below 48hz for JLH to handle), do I have to use an active crossover from the pre-amp to feed
A/ 48hz and up to the JLH
B/ 48hz and down to the subwoofer amp?
but according to the spec will there be a missing gap between 40hz and 48hz?

I think I can not use the crossover from the subwoofer it has no line level output to feed the JLH, correct?

Any comments and suggestions are welcome for I have no clue...
Regards,
Chris
 

thylantyr

Member
2001-02-19 10:38 pm
Mars
I'm generalizing since I'm not familiar with that equipment.

This is one method for active crossover use,
showing a seperate music source, a seperate
active crossover module and seperate amplifier.

Music source line output connects to the active crossover's inputs.
Active crossover output(s) connects to the amplifier inputs.
Amplifier output connects to speakers.

2 way active crossover example;
two inputs (left + right)

high pass output (left + right)

low pass output (left + right) *or* single mono output *or*
(left + right ) w/mono switch.

Some crossovers have independent adjuments of
high pass and low pass frequency and maybe even gain.
Example, you can set high pass to 80hz and low pass
to 60hz if you wanted to. Why would you do this? Who
knows, but it allows you to do anything.

Some crossovers are not independent, setting the crossover
to 60hz will automatically set high pass = 60hz and low pass = 60hz.

If you want to connect your main speaker to operate
at high pass 48hz, then you need an active crossover
that has a 48hz setting. Use the high pass output
of the crossover and connect this line to your amplifier's
input. Then take the low pass output and connect it
to the subwoofer amplifier.

-------

If you have a subwoofer + amplifier combination
with built in active crossover for the subwoofer
you need to find out if it also has a high pass output.
If yes, then you should be able to connect your music
source to the inputs of the subwoofer and then connect
the high pass outputs to the amplifier driving the main
speakers. When you adjust the crossover frequency
of the subwoofer, ie, you set it to 48hz, then
you should get 48hz to the subs and 48hz to the mains.

Adjustable the crossover frequency when listening to
music to fine tune what gives you the best sound.
You don't have to use exactly 48hz, you many like 40hz,
45hz, 50hz, 55hz, etc better.
 
If decided not to buy an active crossover

Is it also possible that open up the subwoofer's internal power amp/cross over to tap into the high pass output and make some RCA output terminals and connect it to feed the JLH before it gets into the power amp for its speaker line out?
I guess the real question to myself is that would I be able to identify/understand the crossover network inside the subwoofer.