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Hi,Have electrostatics and would like to bi-amp and add subwoofer and crossover around 120 Hz. I see most people are using active crossovers. Why isn't simple line level low pass and high pass filters a good idea?
Thank-you,
Fred
Follow Ups:
You may be able to add a passive crossover without adding any new components. Tube and even solid state amps often have capacitors in series with the signal to prevent passing DC voltage. You can size the capacitor smaller to roll off the signal below 120 hz. This is the best situation for crossovers because the smaller capacitor of the same make sounds better than the larger one and it can often be replaced with a higher quality one that sounds much better than the stock capacitor.Retsel
Passive crossovers at the input to the power amp is fine. As Russ said it is best left to first and second order filters. Active filters are not difficult to design and build. It can be done with one tube or transistor per first or second order filer.For what you are attempting to do I would consider letting the main speakers run full range and trim the sub crossover to blend in as best as it can.
"I see most people are using active crossovers. Why isn't simple line level low pass and high pass filters a good idea?"I may be nit picking here but "Line level" refers to the small
signal(s) between components before it's amplified by the power amp and sent to the speakers.Active crossovers are considered line level components so my question to U is, are U refering to high level or speaker level crossovers in your question or R U refering to implementing a line level X-over before the power amp(s) using discreet components?
Cheers,
~kenster
I am refering to implementing a line level X-over before the power amp(s) using discreet components.I would like to thank everyone that has responded.
Ok.There R several companies out there that offer line level in-line x-overs like U are interested in and Harrison Labs is one of them.
I've included a link to the PFMOD 2W-1 that U can peruse and if this unit piques your interest, I have one I am no longer using that U can try in your system if U want.
Cheers,
~kenster
That is a very nice offer. I looked at the site, mentions low pass is mono, can it also be used sterero? Is there a way I can contact you? My E-mail is fred_troy@hotmail.comThanks again,
Fred
Yes, the website mentions that the low pass is mono-mixed but the instruction sheet that came with the unit makes no mention of this and indicates that the low pass section has left and right outputs.The low pass frequency can be selected independantly for each channel so this would indicate that the low pass is in stereo.
I used the unit with a single sub so I never explored the stereo sub route.
I will contact U via E-mail.
Cheers,
~kenster
Fred,> Why isn't simple line level low pass and high pass filters a good idea? <
Passive might be okay if the connecting cables are very short. But there could also be an interaction between the crossover's capacitors and the capacitance of the cables. Another issue is it's more difficult to make a crossover that's more than 6 dB per octave using only passive components, without the interaction mentioned above.
--Ethan
But a passive filter only has loss. Plus you are pretty much stuck with first or second order unless you want to use inductors. The inductors get big and costly in a hurry.But if gain isn't a problem and your preamp can handle driving them I think it is the solution.
Russ
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