Capacitor as Crossover for High Pass?

Next crossover Slopes?

Could I get some thoughts on slopes to use on both active (for the low pass) and passive (for the high pass)?

Is there a reason you wouldn't want to use 8th order slopes? Complexity, noise? It would seem that one would want to use the greatest slope and place the two crossover frequencies within exactly an octave of each other (say 125hz for the low, 250hz for the high)? Would not the drivers then be either positive or negative the same "amount" throught the slopes.

If so, would the object be to have both drivers, in this case the mid and the woofers, carry some of the frequency range with one driver negative and the other driver positive through the slope as they approach a crossover point exactly between the two crossover frequencies? In essence the frequency ranges between these two points are flat without any (+/-) overlap?

Or would it be more of a blend of slopes with one of the driver types "carrying more" of say the bass frequencies towards a point between the two crossovers?

I understand I am being very simplistic here. I imagine differences between speaker types, volumes, phasing and type/wattage of amps come into play.

Lee

Hi Lee,

IF the satellites are reasonably flat to a frequency that is "significantly" below the chosen crossover point, and IF the bass panels are reasonably flat to a frequency that is "significantly" above the chosen crossover point, then you want to have the SAME 3db bandwidth point for both the high pass and low pass filters. What is referred to as the crossover frequency would correspond to that 3db bandwidth point, and at that point each filter will have rolled off by 3db relative to the response further into its passband.

So if you choose both "corner frequencies," as they are also called, to be exactly the same, and if the slopes are the same, then the overall response will sum to flat.

When I used the word "significantly" in the first paragraph, how significant that is will depend on the sharpness of the filter slope.

That is all a different situation than in the design of INTERNAL crossovers within speakers, where the choices of corner frequencies and slopes may differ between the high pass and low pass parts of the crossover, in order to take into account differing driver characteristics near the crossover frequency.

Assuming the criteria of the first paragraph are applicable, if you use a passive high pass filter, it seems to me that you also need to use a 6db/octave (first order) slope on the low pass active filter, or a mismatch will occur.

If you implement both the high-pass and low-pass filters actively, then you would have the flexibility to choose both slopes to be anything you want, within the range of selections that are offered by the electronic crossover.

My understanding is that while very sharp slopes may be beneficial in keeping the input frequencies to each speaker within the speaker's comfort area, the downside may be increased artifacts in the crossover, such as passband ripple in the frequency response, and phase anomalies. Those are complex areas that I'm not particularly familiar with; perhaps someone else will provide additional insight.

Best regards,
-- Al

Understood.

Thanks again!

I just picked up on this thread today. I haven't been posting on Audiogon for long, but I've been in or around speakers and building for 32 years. A Simple capacitor circuit should not cause any damage to your speakers or amplifier. What you will find is that your panels will swing in impedence at given frequencies and your capacitor will not properly cross your speakers at a given point like your are probably after. If you can get impedence readings, you can put a simple impedence correction circuit in your speaker leads at your speaker to help. This is common and works, but when you say thay you are using panels, I assume that you mean planars, ribbons or electrostatics. Electro statics will not like a cap, planars and ribbons will handle the cap, but correction circuitry will most likely stabilize them at a lower impedence. With all this confusion said, it is a much better idea to go active filters... Unfortunately a poor filter can really contaminate the sound of a good amplifier and a great filter is a lot of money. My best advice is to use your panels full range and adjust your subwoofer to blend or spend the money on a good high pass active filter. Some panels do have some pre made crossovers for passive high pass (maggies). Good luck

Sorry, I just re read the thread and mis read a bit. I would not use panels for bass. I gave you info for panels as your main speakers and traditional drivers in a subwoofer. This should make my posting make more since.
Other mentioned phasing and frequency ripples. At the low frequencies that you are talking about using, there should not be any issues here. 36 or 48 db per octave @ 100 hz will do a good job, I would not cross the woofer at 125hz, even with steep slopes, on occasion it will become directional, you will hear where it is in the room. Try to keep your crossover at 100 or lower. The higher the frequency the more phasing will be a problem in imaging. In the lower frequencies, it will can affect bass output if the drivers become too far out of phase, but this should not be a big problem with active crossovers. Good luck