combine active and passive crossover in the same speaker

[Urotdukidoji]

Hi everyone, I'm looking for advice on how to make the third channel active on my current speakers, which have second-order crossovers at 3kHz and 400Hz with a minimum impedance of 6 ohms.
The highs and mids would be filtered by the passive crossover and powered by 150W in Class D.
A mini DSP would act as a crossover for the lows, which would be powered by 300W in Class AB. The passive crossover is designed for bi-amping, and the low-frequency section can be removed.
What do you think? Is my approach correct, or am I overlooking something?

 

[Urotdukidoji]

The configuration would be as follows:
Denon AVC-X3800H > L and R preamp outputs > 2x4 MiniDSP > Outputs 1 and 2 of the 2x4 MiniDSP > Class D amplifier > Passive crossover for tweeters and midranges. And from outputs 3 and 4 of the MiniDSP for crossover and delay > Class AB amplifier > Woofer

 

[DVDdoug]

Something like is that is a "normal option" with audio video receivers. Bass Management sends the low frequencies (usually below 80Hz) to a line level output for an active subwoofer. The higher higher frequencies go to the main speakers. If you can have full-range main speakers you can turn-off bass management and the sub will only be used for the "point one" channel, and the sub won't be used with regular stereo.

 

[Urotdukidoji]

Something like is that is a "normal option" with audio video receivers. Bass Management sends the low frequencies (usually below 80Hz) to a line level output for an active subwoofer. The higher higher frequencies go to the main speakers. If you can have full-range main speakers you can turn-off bass management and the sub will only be used for the "point one" channel, and the sub won't be used with regular stereo.

What I'm looking for is a full-range speaker, well, more or less, because it goes down to about 30Hz, but with an active bass driver. My system is multi-channel; I already have subwoofers. This would be for the 400Hz to 50Hz range.

 

[Urotdukidoji]

https://www.audiosciencereview.com/...ersion-to-four-way-active.52624/#post-2363511

This all stems from a previous thread where I showed a disastrous set of speakers I refurbished. They were supposed to be passive full-range speakers with a built-in active subwoofer, but they never worked properly. I redesigned them and made them passive, but you know how it is... it's never-ending.

 

[a4eaudio]

Look at the Barefoot01 studio monitors (I think the _03 also). Passive crossover between tweeter and mid-range and active between mid-range and woofer. This allows them to use a two-channel amp for a three-way speaker. One channel powers the T-M combo with a high-pass filter at 350Hz and the other posts the woofer with a low-pass filter at 350Hz.

 

[OldHvyMec]

What do you think? Is my approach correct, or am I overlooking something?

I have used the same approach for over 45 years. Except I use valves for the mids and highs, which happen to be EL34s/KT77 or KT66 (Cary V12Rs), depending on my mood, and Behringer DCX2496/NU12Ks for sub/bass duty for the last 20+ years. I was using an active design by James B. with Threshold A/B amps designed/modded by a Pass amp repairman and builder, before that. I changed to class D Behringer DCX2496/NU12,000 about 20 years ago. I had more options with that setup, and it ran a lot cooler.

Recently (2016) I started using Nord One-Ups NC500oems with rev D boards for the summer to cool the whole setup down by a considerable amount.

The change to class Ds for the mids and highs is quite good, but I usually can't wait to change back in the cooler months, as I always liked the combo of small planars/ribbons and valves (preferably EL34/KT77). I also liked using a modded (by Samra) McIntosh MC240 for the mid/highs. Something about an MC240 when using factory valves that are closely matched and kept in good working order. RCA/Telefunken in the old Macs work together like peas and carrots.

C20 (or C11/C22)/MC240 are timeless for mids and highs using the passive 12db factory XOs designed by Brian Cheney and the Neo 8, AC ribbons in the RM30, RM40, or RMx Elixirs. I've never heard or owned better, especially for the cost at the time. I just purchased a factory set of RM30s with under 500 hours for $1,100.00, still in the factory wrap. I've looked for better, but the cost is so high, I'll stick with what I currently have. RM30 (2 sets), RM40s (1 set), RMx Elixirs (1 set), they will outlast my great-grandchildren with very little maintenance. I have about 9K in total (over a 20-year period). I purchased them all used, or they were used factory returns for whatever reason.

I've measured them a few times, and they do have a slight bump at 1khz, BUT simple tone controls, especially with an onboard EQ like a C46-55, have worked quite well if you/I really need to have a flat response. Personally, I don't. I still prefer the older valve gear. Their imperfections add up to perfect imperfections to my old ears.

Enjoy and Regards

 

[Fledermaus]

This is also the approach I took for my 1st DIY 3-ways : DAC -> DSP X-over and EQ -> 4 channels out to 2 x 2-way amps, one for bass cabinets, one for passive X'd-over mid-high boxes.

Provided your passive XO gets the phase right, the DSP even allows you to EQ your mid-high section, see :

BTW, you might consider shorting your midrange passive HPF and entrusting it to your DSP, as per above.

 

[Chrispy]

What are the specifics of speaker/passive crossover? Other gear involved where you can provide an electronic crossover? By woofer do you mean sub?

 

[Urotdukidoji]

Por cierto, podrías considerar acortar tu filtro paso alto pasivo de rango medio y confiar esa función a tu DSP, como se indicó anteriormente.

Thank you all very much for your replies.
That's exactly the configuration I'm planning to use.
My setup would be that, using the miniDSP as a crossover and a DSP for the low-frequency range, from 400 to 50Hz.

And once integrated, I'll let Audyssey (currently without Dirac) handle the integration with the subwoofers and room correction.

Is it advisable to apply an electronic high-pass filter between the bass and midrange frequencies?

 

[Urotdukidoji]

¿Cuáles son las especificaciones del crossover pasivo/de altavoz? ¿Hay algún otro equipo involucrado donde se pueda proporcionar un crossover electrónico? ¿Te refieres a un subwoofer cuando hablas de woofer?

It's a second-order filter at 3 kHz and 400 Hz, with the low range physically separated from the mid and high frequencies. The bass filter would be omitted and replaced with a mini-DSP. It would consist of two three-way speakers with a frequency range of 30 Hz to 20 kHz, powered by two two-channel amplifiers. For the front left and right channels of a multi-channel system, the crossover frequency would be 50 Hz, and from there down to 20 Hz, four subwoofers would be used.

 

[terryforsythe]

Is it advisable to apply an electronic high-pass filter between the bass and midrange frequencies?

I am assuming the bass drivers are in the same cabinet as the midranges. If so, yes.

 

[Urotdukidoji]

I am assuming the bass drivers are in the same cabinet as the midranges. If so, yes.

The bass driver has its own enclosure. In any case, it's easy to test with the active crossover.
I'm recovering from a minor operation, and I have some free time ahead of me.

 

[Urotdukidoji]

What a mess I'm making with the translator...

 

[terryforsythe]

The bass driver has its own enclosure. In any case, it's easy to test with the active crossover.

At a 400Hz crossover frequency, you probably will want the bass cabinets immediately next to your midrange/tweeter cabinets (e.g., right below them).

I'm recovering from a minor operation, and I have some free time ahead of me.

Make a full recovery!

 

[dualazmak]

My post here would be of your reference and interest, I assume.

Even in such a "quasi/sham-multichannel" setup, if you would like to have more definite separation of Fq coverages of woofer and sub-woofer, I suggest you adding a steep high-pass (low-cut) passive filter at around 70 Hz in the "passive network" so that your woofer would not receive sound below say 60 Hz; you can ignore this if your present amplifier (or preamplifier) has such separation mechanism of Fq-zones for woofer and sub-woofer.

You would please notice, however, we always have Fq zone where woofer and sub-woofer sing together even whatever steep filter(s) (active or passive) would be applied (ref. here).

Of course, you need to objectively measure the actual room air sound using measurement microphone, at you listening position in your own acoustic environments, for semi-optimization of Fq-SPL curve (including proper gain matching among the SP drivers), phase/polarity continuities, EQs, group-delay features, etc. in addition to your intensive subjective listening tests.

Based on my actual rather intensive experiences on such "quasi/sham-multichannel" setup, I think you can learn a lot prior to going into fully active multichannel multi-amplifier setup eliminating all the passive networks (and attenuators if you have any).