Active Crossovers, anyone dabbled?

[mandryka]

I love active crossovers and have a few retail versions in my collection

Esposure V - I have two of these for NAIM SBL and IBL
Exposure VXN 2-way to be used for NAIM S600 Ovators work in progress.
NAIM SNAXO 3-way for NAIM NBL
Exposure VXN 3-way balanced (four box affair) to replace the above SNAXO
A very old first gen NAIM 2-way board only for a project still in gestation!

I was interested in giving the MINIDSP a go but have yet to go there.
I have looked at the sublime kit especially the very new release which has a discount for early adopters.

The XKitz looks interesting but they have had no stock for long periods now.

Do any of these have a control to adjust the timing? I have an active crossover for ESLs and passive subwoofers with a timer alignment control - I've learned it can really matter. The Sublime Acoustics product in the OP doesn't - it may work well enough for you, you may get a coherent enough image. But you may not.

 

[S-Man]

I’ve been using an active crossover between main speakers and my bass extenders for many years. I am still experimenting with trying to get a transparent unity gain stage and its associated power supply. It’s absolutely not trivial!
I have tried op-amps, Naim TA buffer and other discrete circuits. Actually, I have some Avondale Audio filter cards which I have working but haven’t put in the system yet. Really must try those, they look promising.

 

[amis]

I mainly listen to my Linn isobarik DMS/PMS in passive tri-amplification with 3 Nap 250 Olive. I think Linn's active filtering is preferable to Naim's snaxo active for the Isobarik. I also have a Naim 3-6-2 active filter fed by Supercap DR, however I prefer tri-amplification with the Iso's passive Linn filter which is excellent. I've owned Naim SL2s, I liked sl2 active with 2x250; but the SL2s play well with 1x250 and the Naim PXO passive filter.

 

[Ben&Ted]

Do any of these have a control to adjust the timing? I have an active crossover for ESLs and passive subwoofers with a timer alignment control - I've learned it can really matter. The Sublime Acoustics product in the OP doesn't - it may work well enough for you, you may get a coherent enough image. But you may not.

None of these have user adjustable time delay and integrating subs perfectly to main 'speakers is hit and miss.
I know that the Exposure V and NAIM SNAXO don't have this but the new EXPOSURE VXN are work in progress for me and Tony Brady at Exposure may have built this in for factory set up, best to check with him.

Integrating subs with ESL's was not straight forward when I had two REL STORMS with my ESL 63's and one more for LFE.
The best integration was using the MERIDIAN 565 and 568 which had basic DSP and the 'speaker set up used distance from each 'speaker to your ear at the seated position to set the time aligned delay (level matching also could be set).
I would position the REL' by ear in the analog domain and switch to the basic MERIDIAN DSP and set the simple digital active crossover and distance settings for each 'speaker.
It was very effective and subs would almost dissapear into the complete soundfield either 2.1, 5.1,7.1 trifield etc.

The active crossovers I have used and listed above are working in the analog domain and do require well designed complete 'speakers 2-way or 3-way design.
The NAIM 'speakers I use were all designed with active network first and then the passive mirrored this as best it could.
IBL, SBL have a slope in the front baffle to time allign the tweeter and mid/base so design stage of the 'speakers is vital in this respect.

 

[SteveG]

I ran a Naim active set-up for quite a few years using an IXO, 2 x 140's and Credos and it worked pretty well.

 

[pocketkitchen]

I had passive Isobariks and started to go active.
I soon realised that it was very expensive to do it it with Naim kit.
Naim no longer support the olive 3 way Snaxo.
I gave up and bought new ATC active 50s.
They give you a 6 year warranty.

Naim no longer make the SNAXO. They do service them though, as with all their other amps.

 

[robbyd]

https://spl.audio/en/spl-produkt/crossover/

 

[dalryc]

Naim no longer make the SNAXO. They do service them though, as with all their other amps.

As of at least March 2023 when I asked them, they refused to service and retune my Olive Snaxo for Isobarik support as the board inside "was long obsolete".
Witchhat were able to retune it in a standard service.

 

[awkwardbydesign]

All crossovers - passive, active or digital - must be tailored to the complement of transducers on a given loudspeaker, if you want them to work seamlessly together. That is because transducers do not behave linearly and they are bandwidth limited. And then there is this thing called relative phase. Bolting on a generic 24dB/oct active filter will rarely achieve a 24dB/oct acoustic crossover, unless there is at least two octaves of linear overlap (e.g. woofer flat to 4kHz and tweeter flat to 1kHz for a 2kHz cross). Double that overlap for a lower order crossover.

I used Jordan drivers, which are wideband, including the 50mm units, plus a SEAS 10" bass driver. And I crossed over at around 4kHz and 300Hz, IIRC.

 

[pocketkitchen]

As of at least March 2023 when I asked them, they refused to service and retune my Olive Snaxo for Isobarik support as the board inside "was long obsolete".
Witchhat were able to retune it in a standard service.

I think you got someone on a bad day which is a real shame. They certainly dropped the ball, at least. I’ve been talking to their head of service this morning on another matter and asked the question, “do you still service SNAXO or NAXO?” The answer was, “Yeah for sure we do - all varieties. For certain we can also configure for different speakers‘ crossover points, too”.

 

[dalryc]

I think you got someone on a bad day which is a real shame. They certainly dropped the ball, at least. I’ve been talking to their head of service this morning on another matter and asked the question, “do you still service SNAXO or NAXO?” The answer was, “Yeah for sure we do - all varieties. For certain we can also configure for different speakers‘ crossover points, too”.

Maybe - it pushed me towards Witchhat who managed to do the work then go out of business!
Shame - they were excellent value for money and great service too.

 

[awkwardbydesign]

All crossovers - passive, active or digital - must be tailored to the complement of transducers on a given loudspeaker, if you want them to work seamlessly together. That is because transducers do not behave linearly and they are bandwidth limited. And then there is this thing called relative phase. Bolting on a generic 24dB/oct active filter will rarely achieve a 24dB/oct acoustic crossover, unless there is at least two octaves of linear overlap (e.g. woofer flat to 4kHz and tweeter flat to 1kHz for a 2kHz cross). Double that overlap for a lower order crossover.

Thinking on this a bit more, isn't the big problem with passive xovers? A 24dB electrical slope will give just that, and also being 360 degrees out of phase is therefore effectively back in phase, just out of time alignment by one wavelength. I time-aligned mine physically. The acoustic slope will be different away from the xover frequency, how far depends on the individual driver's limit. No reactive components in the speaker will minimise phase problems too.
N'est-ce pas?

 

[James]

Thinking on this a bit more, isn't the big problem with passive xovers? A 24dB electrical slope will give just that, and also being 360 degrees out of phase is therefore effectively back in phase, just out of time alignment by one wavelength. I time-aligned mine physically. The acoustic slope will be different away from the xover frequency, how far depends on the individual driver's limit. No reactive components in the speaker will minimise phase problems too.

All analogue crossovers (and maybe digital ones too) cause phase shift. It is unavoidable. Time alignment is a bit of a red-herring, because you cannot really discern even a few wavelengths of relative delay as long as they are in phase. Otherwise, sitting non-equidistance to a loudspeaker pair would sound really odd. The important bit is that the filtered drivers' outputs are mostly in-phase, which is achieved by aligning their acoustic centres and paying attention to electrical polarity.

The only big problem with passive crossovers is that they work in concert with the driver's impedance. So a 'textbook' LR4 filter predicated on 8R impedance should, in theory, yield an LR4 acoustic crossover. Two things get in the way. First, there are no drivers with flat impedance, so that throws the electrical transfer out. Second, drivers rarely have a flat response, so that throws the acoustic transfer out. Active crossovers don't have the first problem, but the second problem will prevail unless the electrical transfer function is designed to accommodate driver response.

When people talk about crossovers, they should always refer to the acoustic transfer, which is the only result that matters. That is the sum of the electrical transfer and the native driver response. It is entirely possible to use a lower-order (electrical) filter to achieve a higher-order (acoustic) crossover. My own Ergo E-IX has acoustic LR4 crossover achieved with second and third order electrical filters designed specifically for the driver complement.

 

[C. Alshus]

I use a Fabfilter Pro Q3 with a Motu Ultralight mk5 dac as an active filter. Works _very_ well.
It plays good on an Eversolo A6 streamer and exceptional on analouge. Measured in room with more than 200 sweeps. Dsp up to around 400hz.

 

[Woodface]

Certainly better value if you buy speakers in active configuration to start with. I had Keilidhs for a while & really liked them at the time. Long time ago mind.

 

[Toaster]

I've dabbled extensively with both analogue and DSP-style AXOs. I like them. Amongst the options I have here is a lot of parts and a suitable MiniDSP crossover for a pair of Nao Note II RS. I really should build them- I expect they're superb. Open source too, now John Kreskovsky's retired.

 

[AndyU]

A couple of studio engineers from Present Day Production have recently designed their own modular upgradeable monitor using plate amps and digital active crossovers. They have posted lots on YouTube about their design; you may be able to glean some useful ideas from them. They just got a decent review in Sound on Sound.

MUM | PresentDayProduction

PresentDayProduction MUM Series speakers are incredibly detailed, dynamic and once you hear them... there's no going back.

www.presentdayproduction.com

PresentDayProduction MUM-8

Can a direct sales model and high‑tech components make top‑level monitoring affordable? Present Day Productions believe so.

www.soundonsound.com

 

[pierre]

I have been playing active for a long time, and I will never go back. The DBX 223 and DBX 234 are wonderful machines for entering into active territory. I've been using the 234 for years and it's pretty good even in high quality systems. See what Troels Gravensen (a well respected loudspeaker designer and long time audiophile) reports here

http://www.troelsgravesen.dk/OB9.htm

See also this technical review

https://www.audiosciencereview.com/forum/index.php?threads/dbx-223xs-crossover-review.35902/

If you have DIY skills and really want the best, consider this

https://diyaudiostore.com/products/diy-biamp-6-24-crossover

Discrete JFET no-feedback circuits, configurable as 6-12-18-24 independent slopes, no gain at the output, only attenuation via trimpots or linear pots, you choose a center frequency and use a trimpot to fine-tune the cutoff frequency... you can't ask for more. These are transparent buffers that only a genius like Nelson Pass can design. They were out of production for a long time, but now they are back! With one board you can make a 2-way, for a 3-way you need 2 boards. Ah! the kit includes matched jfets!

Another very good option is the classic

https://sound-au.com/project09.htm

This is very good and much better sounding compared to the DBX 234, but not comparable to the Pass xover. On the other hand is easier to build.

But let me say something about active systems in general for hi-fi use. Most people think they are easier. Yes, it's easier to set relative levels and you have more freedom to choose drivers... but in an active system what you hear is the sound of the driver loaded in the box... nothing can save a bad sounding driver. And when you join this addictive world of active hifi you realize that, despite datasheets curves and parameters, each drives has its own sound which cannot be predicted by the frequency response at all.

Also, never use 24 slopes unless the two drivers overlap flat at least an octave (the more is better) below/above the cut. Furthermore, for mid/high transitions, I'd avoid a 24/oct because it would scream in your face the difference in dispersion between a cone and a small dome. That's why a 4-way active system is easier than a 3-way active system. It's easier to smooth out the transition between drivers' sizes. In my experience, going active above 500Hz doesn't make much difference anyway, it just adds more complications.

Hifi is different from PA because you listen more closely and pay attention to details instead of smoking and jumping like at a rock concert.

Pierre

 

[pierre]

Digital xover makes sense only if you don't listen to analog sources. But even in the case that you listen to digital only.... I'm not sure about most DSP machines. They can do whatever you like with a couple of clicks, but all those I tried sounded like cheap dacs, in most cases they need extensive tweaks on the output stages to sound right.

 

[gingermrkettle]

If you have a bit of DIY nous and want to dabble, the KMTech boards work well, I have used a set of the 24dB LR crossovers for the Ruark Equinoxes in my mancave system (and Tannoy 607s before that) and they work very well.

NEW VERSION v1.3 LR mono 2-way active filter KMTech PCB DIY NEW FEATURES | eBay

Manufacturer: KMTech Design (UK). A high performance active crossover filter by KMTech Design. Filter Gradient: 24dB/octave. PCB Mounting: 4mm mounting hole each corner. NEW FOR VERSION V1.2 Crossover Frequencies: User-definable by changing resistor values.

www.ebay.co.uk