Ah, I see. I haven't kept up with new models from Rythmik. A pair of HX800's makes a lot more sense than four A370's!
DSP Active Crossover
I'm considering trying a DSP-based active crossover in my system. I did a search to see how much this has been discussed, and most of the posts are pretty old or about active speakers. DSP technology has changed a fair amount in the last 15-20 years.
My system is digital only, and my speakers are 3-way, so it's not particularly complicated. I've been looking at the Danville Signal dspNexux 2/8 which has two channel in (with digital inputs) and eight balanced analog outputs. This appears to be available with AKM AK4499 DACs which are fairly well regarded sigma-delta DACs (although I don't know how good their implementation is).
This product has a fairly rich DSP software environment for programming filters, time delays, etc., so it should be fairly straightforward to set it up to replace my passive crossovers.
My biggest reservations are 1) giving up my Denafrips Terminator+ DAC and nice-quality DIY preamp, and 2) using the DAC's digital volume adjustments.
This unit is about $3K (maybe a bit more with the AK4499 DACs), so isn't terribly expensive. From the limited research I've done, this unit appears to be higher sound quality than the miniDSP or DEQX boxes, but I could be wrong. All my amps have balanced inputs, so I'd prefer to use a unit with balanced outputs.
So, what I'm wondering is if the benefits of active crossovers and dsp equalization will outweigh the lesser DAC quality (assuming this is the case) and lack of analog volume control (currently using a relay switched attenuator). I'm also wondering if there are other dsp audio processors that I should consider (digital inputs, at least six channels out, ideally with balanced outputs).
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Why talk to Danny Ritchie or anyone else. Just call Al Clark at Danville. Interesting guy, claims to have design more DSP boards than anyone on the planet, but has an analog background as well. And Al is generous with his time as well. I purchased the Nexus DSP and love it. I’ve never tried the miniDSP products, but can’t imagine they are as good. The brand new DEQX boxes are probably 2X or 3X the cost. |
Hard to say how complicated this will be without knowing your system, and what the passive crossover does. While setting a DSP crossover is as simple as moving sliders around on your screen, entering the right values is more complicated. A crossover in a passive speaker is almost never "just" high and low pass slopes, but I suppose crossovers for high efficiency speakers are often close to that. The real question is how well you are able to analyze the current behavior of your speakers and to make the appropriate adjustments. |
@erik_squires - My system is described on my Main System virtual system page, but to elaborate a bit more - my speaker system is a dipole line array with Bohlender-Graebener NEO10 midrange drivers, and NEO3 tweeters, with dipole woofer towers, each using four 12" servo woofers. The BG drivers have a fairly smooth response, so the crossover is fairly simple - 12 db/octave LC filter for both NEO10 and NEO3 driver arrays, with an additional LC notch filter on the NEO10s. The woofers are driven by Rythmik plate amps that have their own active crossover (along with a simple parametric equalizer). I don't think it will be hard to set up a DSP to do the same thing, although I'd probably use a 4th order crossover since it's fairly simple to do with DSP and makes it easier to get a smooth phase response. The NEO line arrays are fairly efficient at about 98db/w. I'm currently driving them (using the passive crossover) with a 300B PSET amp (monoblocks). With an active crossover, I'd probably continue to use this amp on the NEO10s and build another SET amp for the tweeters. I may be able to bypass the crossover on the Rythmik amps when using the dsp. If not, I'll set it to it's maximum crossover frequency and work around it with the dsp. I currently use REW with a calibrated UMIK-1 mike. I suspect this will be adequate to set up the active crossover, but I'm open to suggestions. |
@jwr159 - I talked to Al Clark on the phone for close to 40 minutes today (he likes to talk) and I'm going to go ahead and order the dspNexus from him. |
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