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).

128x128jaytor

@ricevs 

When my TacT 2.2x bit the dust the DEQX was still two months away. So, to fill in the space I got a MiniDSP SHD $1500 with UMiK 2. The Pre 8 is still one month away, so I will be glad to tell you what I think after a week with the DEQX. All I know about the processor at this point is that because of Covid and delays in getting the first processor they redesigned it for a new and better processor that became available. It is a 64bit floating point system. It also shot the price up a couple of grand. My 25 year old TacT sounded better than the MiniDSP. Lets face it the MiniDSP has 4 DAC channels and two ADC channels, It also streams and handles DIRAC Live. That is a lot of stuff for $1500. Benchmark Media Systems is using an SHD Studio and two of their own DACs and think it is great. That is a $6000 proposition. That is a tempting second choice if the DEQX is too rich. The SHD has a slight graininess to it. It is not crystaline. The TacT was, and as long as you had a computer hooked to it you could do anything and I do mean anything. I am not sure yet how a computer relates to the Pre 8. I do not even have a manual yet and yes, I asked for one.

@ricevs ,

No, you can not parallel SHDs. The Dirac Live only knows about 4 channels in the SHD. As far as the crossover are concerned you might be able to double it up although I think that is a silly proposition. You are much better off with Dirac Live than a three way crossover. It is hard to explain to people what total control over a system/room's amplitude response means or sounds like. You have to hear it. 

I don't understand how you were using a Tact for bi-amping.  Does it have analog line level outs?  Or is this a digital out for subs?  Or two sets of digital outs?  And how were you using the SHD?  Analog outs or digital outs?  And if you are using digital outs what external DACs were you using?  Graininess in what configuration and compared to what?

Jaytor,

How is your active system doing?  How does it compare with the passive version?  Any tradeoffs?  My friend in Panama owns the very first Line Force speaker that Danny made and was made from Aluminum.  I just sent him a modded Peachtree Gan1 amp to use on the panels.  He modded the passive xovers with my suggestions.

@ricevs - Unfortunately I haven't had a lot of time to work with this yet. I've been buried with work (I run an ecomm business and do all the coding - getting ready for the holidays) so this has taken a back seat.

Setting up the dspNexus means I have to disconnect my passive crossovers,  set up an extra pair of amps and get everything plugged in, and change the settings on my subs, so takes a while. And then takes a while to switch everything back. So I have to be able to dedicate at least 4-5 hours to make it worthwhile and haven't had that much free time in one chunk in a few weeks. 

Once I get into November, I should have more time since I don't like to make changes to the websites during the holidays. I'm planning to attend CAF next month and look forward to discussing my setup with Al Clark and Richard Hollis. 

So far, I have gotten a simple crossover setup to work, with a limited amount of equalization to the subwoofer channel. It sounded ok, but will clearly require more filter tweaking before I can decide whether I like it better than the passive crossover.