Digital crossovers


Are crossovers "tone killers" as Zu Audio says?

Are digital crossovers a solution?

Much of our source material is digital already: e.g., CDs, ripped CDs, downloads and internet listening.  I wonder if a digital pre-amplifier separating the music by frequency and sending the result via the analogue amplifier direct to the appropriate driver would/could produce awesome results?

(I wonder what the crossover slope would be? Would it be absolutely discrete, with absolutely no overlap between drivers? Or is a small amount of overlap necessary even in the digital world?)
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I'm a fan.  I use an Onkyo pre-pro in my all-digital system to cross my main speakers to subwoofers (the mains are two ways with traditional, passive, analog x-overs at the tweeter cross).

All digital, multi-way x-overs like DEQx can sound great, too.  One manufacturer (can't recall the name right now) offered an active version of his best speaker using that device to actively cross and tri-amp the individual drivers.  I heard it at a show and - tho it's notoriously hard to judge in those environments, I thought he got excellent results,  

Unfortunately,  I prefer omnidirectional mains and haven't found a good option for that mash-up.
BTW,

I'm not 100% sure, but I believe that DEQx allows you to choose your slope, maxing out at something like 300 DB/octave.  So, yes, without phase concerns, you can go to brick wall type slopes with digital x-overs.


If your used to the sound of a dac or cdp that is "hi-end sound" with well implemented d/a converters, I/V stage, and output buffer, the there is the chance a digital xover which will take the place of your "pride and joy" will let you down.

As it will take the place of your well thought out cdp/dac. And from what I’ve seen there is no striving for perfection digital xovers with well implemented d/a converters, I/V stages or output buffers with digital xovers, they all run pretty much text book in this regard with no forward thinking at all. Like feedback free discrete I/V stages, discrete output buffers, clocks that are better than the norm. Sure they do the digital xover thing fine, but the rest of the sound may leave you "cold" like a run of the mill dac/cdp can sound.


Cheers George

On the face of it, I tend to agree with George here since at least one of the things we may be dealing with here is having 2 D-A conversions in the signal path...first from your CDP/DAC and then the digital crossovers. What's more is that this last conversion may be 24/96k or even less and if you already have 192k or better at the first conversion then there might be a slight reduction in extension or openness in the highs...however, considering the possible gains, this may actually not be a deal killer for you...I know it certainly wasn't for me. But, then again, my situation is different, I already had over $10k of electronic noise reduction gear (Alan Maher Designs) to tame all the digital noise, AC and DC noise in my setup so all the usual complaints of "digital sound", as George rightly refers to above, were entirely put to bed. But, all that may be the biggest thing: once you commit to a digital solution of this kind, you may find yourself wedded to solving the 'noise problem' somewhere along the way - to finding some kind of conditioning, noise reduction or *something* that will fit the bill and get everything to fly right for you. Once that's done, then yes, digital does indeed fulfill its promise of being far better than analog in this app.

All of this assumes your digital crossovers are in fact adjustable...flexibility is key here since that's what allows you to dial in the sound according to Your tastes, Your room, Your gear...and you may not really know in advance what those parameters are until you actually have the ability to play around with them all. Overlap to me is a disaster - getting rid of it can offer you a whole new listening experience. I tend to agree with Zu about the "tone killer" thing, but maybe even bigger for me was the complete liberation of the entire dynamic envelope...no more power-robbing passive parts to blunt the dynamic peaks. It's been said that amps communicate directly with the passive crossovers - take them out and the amps communicate directly with the drivers - from my experience there is indeed an enormous difference to be heard there. 

Which brings me to one more thing. Your speakers (drivers) must be up to the task of the increased performance levels...that is they must be an inherently good match for each other (in particular, overlapping well in the crossover region, hopefully allowing some room for moving the crossover point around at least a small amount should the need arise from your experimenting with things...but they must also be capable in terms of dynamics). Not all speakers come with drivers as inherently well matched as that. Knowingly or otherwise, speaker designers notoriously effectively use the the power-robbing and resolution/tone-diminishing nature of their own passive crossover designs as a means to hide less than ideal driver matching. Removing the passive crossovers may reveal the limitations of driver matching that the speaker designer didn't intend you to know about. Not All speakers have this problem, but those kinds are out there, so beware and take things slowly maybe.

However, with all that said, I'm a huge believer in digital active crossovers...under the right circumstances they are in fact a dream come true. FWIW, I use the set of digital pro tools included with 3 Crown XTi 2 amps run from my CDP to a pair of Wavetouch Grand Tetons with a pair of DIY sealed subs. Had to radically modify the tweeters to get the sound to my tastes (had nothing to do with changing to digital crossovers), but under the Alan Maher Designs umbrella here anyway, everything is just amazing across the board - and *despite* that the 2nd conversion at the amps is only 16/48k! In my own case, all the AMD stuff here was a much bigger influence on the sound than even the active tri-amping itself - which I now consider to be indispensable.

Hope this helps.

I use the Velodyne SMS 1 for the low pass to my sub.  It's a digital crossover with a parametric EQ.   I run my mains full range with no high pass x-over employed.  I've never been a fan of EQ or tone controls but I have a nasty room mode at 40Hz that muddies the sound and makes everything seem bloated.  That said a number of the speakers I've owned are stand mounted small speakers with a sub.   The SMS 1 not only allows me to flatten that hump,  it does a great job of integrating the sub with the mains.  I can select the x-over in 1 dB steps and choose 6 dB through 36 dB slope / octave.  I use a steep slope right around where my mains roll off and it eliminates that double bass that can occur in the x-over region.
An additional AD/DA step shouldn't be necessary if the entire system is properly designed. The digital crossover would accept the digital out from a CD player, media player, and computer.

Of course, a digital crossover would require a dedicated amp for each output range, be they built-in to the speaker or stand-alone.

And if one wants the option to use a specific DAC, then the digital crossover would need to have a number of digital outputs (no biggie), each requiring its' own DAC (biggie).

.Hmmm maybe a digital crossover is too much bother for the benefit.

From what I've read, Avante Gard Zero 1 is a very intriguing implementation of a self-contained self-powered digital speaker. But then one speaker communicates to the other wirelessly ... at 16/44.1 ... all that effort then dumbed down unnecessarily at the last moment!!!!
Yes, it is currently a lot of bother to go this route. Agree with you, too, on the Avante Gard. You’d think by now someone would’ve figured out a semi-reasonable way like that to do it....even if it was a proprietary approach that did mean sacrificing some mix-n-match capability among brands for the sake of minimizing cost, complexity and technical redundancies...in fact I don’t really see what’s stopping anybody from doing it that way...they just may have to be able to update the level of DAC performance now and again... ;-)


Ivan,

I believe that Salk offers (or at least once offered) an option along these lines.

You might also be able to do it with DEQx and something like the Linkwitz Orion. The Orion features a separate, active (analog) x-over box, which you’d either delete from the order or (if that’s not an option) discard. Instead, you’d run a digital source signal into the DEQx, adjust the x-overs to taste, and take analog out of the DEQx to the amps of choice - then onto the various inputs of the Orion’s drivers.

I'm not 100% sure, but I think it would work.
With the exception of an analog input, there are a number of digital EQ options like DEQX that can provide a digital output (as well as taking digital inputs), so there is no need for unnecessary A/D/A conversion if one wants a different DAC to handle those final analog out duties. The DEQX is remarkably transparent in its A/D conversion (I was pretty shocked, to be honest). And the quality of the DAC has not felt lacking to me. Of course there may be less successful A/D/A implementation in other devices. 
The DEQx has always indeed looked to me like an intriguing piece of gear and even more so now in view of Roscoe's comment above about the sound of the DAC. If I weren't enjoying my current setup so much I believe I could be tempted to "kick the tires" on that one and take a very hard look...all that and phase response correction, too. Thanks guys.

Are crossovers "tone killers" as Zu Audio says?

Are digital crossovers a solution?
That’s Zu Audio’s opinion & no wonder since they sell cross-over-less speakers! No conflict of interest here!! ;-)
No, cross-overs are not tone killers IF you implement this correctly & that takes some doing....

All digital cross-overs? Try the Meridian (Boothroyd-Stuart Meridian, a UK company) solution. They offer an all-digital system all the way to their speaker. The D/A occurs in their speaker + the speaker is active i.e. has its own amps inside the speaker box.
How many people you know & know of own Meridian? OR, own that style of audio solution?
Does the answer tell you something??