Active analogue high pass/ low pass filter

[markof]

I've been listening to several podcasts recently concerning sub/main speaker management eg https://overcast.fm/+Mn2xGcCSk

In short, the subject of using active high and low pass filters to split the signal into mid-high frequencies to the main speakers and low frequencies (say below 100 hz) to an external active sub has come up several times.

An advantage noted is by taking some of the work-load off the main speakers and reducing the thermal effects on the mid/upper-bass driver, a more linear response from the main speaker is maintained for a longer period of time.

I would guess the filtering would be done between the dac and amp and would best be done in the analogue domain to avoid noise/loss associated with redigitising the signal.

Has anyone here tried such a filter and come to a conclusion? Any recommendations?
I'm curious about the pro's and cons, especially regarding effects on the main speakers tone.

Mark

[Fran]

In short, I've looked at this a few times but never did it.

The other system that is maybe easier to do is to do the split at line level and then amplify after that. Designs for these passive line level crossovers are out there but again, never tried them. In theory it would be a lot easier to do this at line level as you wouldn't need the power handling, plus you could adjust each output to match whatever amplification you had afterwards.

[Rocker]

Could be expensive! You need an amp for each frequency band and cables etc. Naim Audio had such a splitter many years ago, I forget what it was called.

[james]

In the late 70's, 80's the top Naim system was the (so-called) six-pack.

A pre-amp (plus power-supply), an active crossover (plus power-supply) and 6 mono power amps feeding 3-way speakers. (The Naim DLB's or the Linn Isobaricks).

So pre-amp + power-supply + crossover + power-supply + 6xpower-amps = 10 boxes

This would take up a lot of space. It was legendary but I never heard (or even saw) one.

[hudo]

I think it only makes sense doing it as active cross-over, before the power amp, like its done in many active speakers that have separate amp for lows/highs. Otherwise you might end up in lots of different problem (phase, volume, ...). And active cross-over is expensive, adds bunch of components to the chain, its a compromise.
For stereo listening, todays good speakers are made to be linear in its designed range, so why change that? Adding a sub, without crossover on the speaker is a way to go. Crossover on main speaker makes more sense with HT setup, where speakers are usually cheap and low quality and have lots of distortion when driven loud.
So whats the problem we're trying to solve? Is speaker driven very loud is distorting because of lots of low frequency? Then cross over is not a problem, but low quality speaker.

[markof]

FYI https://sublimeacoustic.com/products/k2 ... -crossover

Mark