Cheapest way to incorporate High Pass filter?

[m R g S r]

Measured with the amps turned off right?
QSC amp input is 10.11 K ohm (20hz high pass)
Denon amp input is ?? (45hz high pass) i cant get a consistent reading on it!! ill keep trying
Preamp output impedance is 2.11 K ohm

[Zero D]

So the QSC amp has a fixed (20hz high pass) & the Denon amp a fixed (45hz high pass) Is that correct ?

And they are MONO ? If they are then you will Only need 2 x the circuits as shown

It would be much better if you could get the input impedances from the manuals, if you have them. If not try & look them up on the www. Either way post back with what they state Then we are good to go

[planet10]

Originally Posted by jbell

FMOD Crossover

An FMOD is an expensive & often less than optimal Passive Line Level Crossover (PLLXO).

This is what ZeroD showed in Post #18. His is the 2-pole version using the input R of the amp as the 2nd R. Because of loading issues, the input R of the amp ether needs to be highish (say 50k plus), or the preamp has to have vanishingly low output impedance.

dave

[m R g S r]

Originally Posted by Zero D

So the QSC amp has a fixed (20hz high pass) & the Denon amp a fixed (45hz high pass) Is that correct ?

And they are MONO ? If they are then you will Only need 2 x the circuits as shown

It would be much better if you could get the input impedances from the manuals, if you have them. If not try & look them up on the www. Either way post back with what they state Then we are good to go

nooo...those are the high pass points which i am looking for. there are no high pass filters on either amp right now. (well the qsc has selectable 30 or 50 hz, neither which i want for my 20hz sub)
the QSC amp is bridged, and the subwoofer output of the onkyo 607 receiver is mono, sooo i'm guessing they are both mono then?
the qsc input impedance is listed as 10k unbalanced, 20k balanced. so the reading i got was pretty darn close.
i've searched high and low for ANY specs on the denon plate amp i have...its from a denon powered subwoofer. dsw 40 is the only model info on the plate amp. i can't find any info on it, except the obvious that i already know. (powered 8" subwoofer...)

[m R g S r]

Originally Posted by planet10

An FMOD is an expensive & often less than optimal Passive Line Level Crossover (PLLXO).

This is what ZeroD showed in Post #18. His is the 2-pole version using the input R of the amp as the 2nd R. Because of loading issues, the input R of the amp ether needs to be highish (say 50k plus), or the preamp has to have vanishingly low output impedance.

dave

well the qsc amp isn't that high, and the output of the receiver was measured as 2.11 K ohm....is that "vanishingly low"?

if not, and this is a bad idea to try this kind of high pass, then i'll just order the mini DSP.

[planet10]

Those impedances would suggest that you are limited to 1 pole.

dave

[weltersys]

Originally Posted by m R g S r

well the qsc amp isn't that high, and the output of the receiver was measured as 2.11 K ohm....is that "vanishingly low"?

if not, and this is a bad idea to try this kind of high pass, then i'll just order the mini DSP.

Good idea, less than 24 dB per octave HP does not afford great protection and wastes power on subs that already drop off at 24 dB per octave acoustically.

[m R g S r]

I just ordered it. The 2 x 4 Guess it'll be useful for other projects / tests as well!!

[Zero D]

@ m R g S r

All the best with your decision

[m R g S r]

Thank you for willing to help!!