Best Active Crossovers?


What are the best active crossovers?

I have a pair of Dunlavy SC-VI, which are four-way 6db slope crossover.

I understand I would need to use Three Krell KBX in series to get 4-way 6db slope (besides 8 channels of amplification).

Do you know of any high quality 4-way active crossover that can be configured to 6db slope (except for the 3x KBX option)?

Thanks!
vn101606
FWIW, Both my main and bed-room systems are actively tri-amplified and I've heard other successful and unsuccessful realizations. I was quite happy to leverage Siegfried Linkwitz's (as in Linkwitz-Riley) design work which just left the soldering to me.

>What are the best active crossovers?

The answer is most likely irrelevant to you because you don't yet have the background to recognize what you need.

Read _Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms_ by Floyd Toole for an idea of design targets and _The Loudspeaker Design Cookbook_ by Vance Dickson for some information on realizing those targets.

>I have a pair of Dunlavy SC-VI, which are four-way 6db slope crossover.

The cross-over network also compensates for driver resonances, applies baffle step compensation, and accommodates the rising response which goes with drivers with low inductance motors as they become acoustically large.

Some of John Dunlavy's cross-overs also adjusted driver Q which in turn affects what happens moving farther beyond the driver's pass-band, phase, and how the speaker sums within the driver's pass-band.

Krell's manual suggests that this can be accommodated, although that would mean paying some one for custom work and you still have topology issues to deal with.

Other generic active cross-overs lack any provision for that sort of thing and won't work well for you. The Pass XVR-1 isn't enough.

>I understand I would need to use Three Krell KBX in series to get 4-way 6db slope (besides 8 channels of amplification).

That won't duplicate your existing cross-over functions that have a lot to do with how your speakers sound.

Passive cross-overs are usually realized using band-pass filters on all but the woofer (low-pass only) and tweeter (high-pass) only. By cascading filters instead of using band-pass filters on the upper and lower midrange drivers you're going to change their phase relative to each other, how they sum, and what needs to be done to their relative levels to compensate. That changes your problem from copying to cross-over design which is a lot more complicated.

>Do you know of any high quality 4-way active crossover that can be configured to 6db slope (except for the 3x KBX option)?

The mini-DSP 2x4 will work for your purpose. Of course, using it will require measuring your passive cross-over transfer functions, and creating DSP filters to match.

That said, if you like your speakers you're better off not trying to "improve" things via active-cross overs unless you can purchase a unit specifically designed for your speakers.

If you want a DIY construction project (perhaps active) find a respected design and build it.

If you want to get into speaker and cross-over design as a hobby after reading both books I referenced, buy yourself some measurement software + hardware, perhaps some cross-over optimization software if you care to do passive speakers, and start with a 2-way.
Thank you!

I am reading the Loudspeaker Design cookbook.

For all I have read, considering the 4-way crossover of the Dunlavy SC-VI has 34 components doing a lot of equalization, it believe I will go with the path of just upgrading the components of the crossover for now and listen to the effect of each component upgrade, starting with the most critical ones.

Sometime in the future I may try the active crossover path, but in a way that I can compare with the upgraded passive crossover. Perhaps with the Holm or DEQX.
Given that the crossover of the SC-VI does have a lot of driver compensation, perhaps best is just to:

1) upgrade the critical components of the 4 way passive crossover.

2) bi-amp using one amp for the tweeter and 5"mid, and one amp for the 8" and 15" woofers. I would have the added control of having two amps per speaker. Should I feed the whole signal to the amps, or put a Pass XVR-1 between the preamp and the four mono-amps? If I feed the whole signal to each amp, the four way crossovers in the speakers would be able to deal with it, as they already do now. There are to pairs of binding post, the to goes to tweeter and 5", the bottom goes to 8" and 15" portion of the crossover.

3) I could possibly use the DEQX HDP-4 in-line Digital to Digital, before the Playback Designs MPS-5 and Krell Phantom, so I would not be using the DAC and PRE stages of the DEQX. I stopped using the TACT 2.2X Digital to Digital because it decreased substantially the level of detail. How good is a DEQX HDP-4 D to D? Much more transparent than the TACT?

What do you think?

Thanks.
Another idea is to put your crossover external to the speakers. That way one can make changes to capacitors, resistors and wireing to dial in the speaker. It also elimates a source of distorition as the crossover in the speaker is under a lot of pressure from the woofers.
Correct. The new passive crossovers will be external. I will keep the original crossovers intact for comparison or if one day I decide to sell. It will be a long multi step process. The first step will use original solen caps and inductors, replacing all resistors with duelund. The second step will be to replace the most critical caps in the circuits of the tweeter and 5" mids. Then the most important components, mostly inductors, in the 8" and 15" path. Then possibly the less critical components. I am thinking about using dh labs Q-10 wire and Mundorf supreme solder. I am wondering what would be the best connectors for the 14 driver wires, since I don't think soldering and desoldering repeatedly is the best way. Any suggestions?