Capacitor as Crossover for High Pass?

Lee, the one issue I see with that (aside from the fact that the monitors might sound better if the deep bass were kept out of them, which as you say can be evaluated later) is along the lines of my earlier comments. The power capability of the tube amp will constrain how much of the SS amp's power can be utilized.

If the bass panels are 4db less efficient than the monitors, and the monitors are run full-range from the 24W tube amp, and you gain-match properly, then the maximum amount of SS power that can be utilized without clipping or overdriving the tube amp (which would result in a highly distorted signal being supplied to the monitors) is:

24W + 4db + whatever amount of headroom the tube amp can provide above its 24W continuous power rating.

4db above 24W is 60 watts. So on a sustained basis you would not be able to supply much more than 60W to the bass panels, or perhaps (just guessing) 75 to 100W on brief transients, regardless of how powerful the SS amp may be.

And those numbers are based on the optimistic assumption that when high volume bass notes occur, there is no significant musical energy present at higher frequencies. If there were, that would add further to the burden on the tube amp, and thereby further reduce the amount of power from the low-pass filtered SS amp that could be utilized without clipping the tube amp.

Best regards,
-- Al

Got it. I'll plan on rolling the lower frequencies off the monitors. If its OK, once I find the panels and start working through the process I'll send an update.

Lee

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!