I've been working with the analogue crossover boards made by KMTech for some time now, trying to keep everything pure analogue for the sake of my vinyl set up. I've done many modifications for various speaker applications, but got a little fed up of the work and expense every time I change a parameter like the crossover point. I've also been keeping an eye on what's happening in the Digital Signal Processing (DSP) market and think its about time I started looking at a digital crossover solution. What tipped the scales, in favour of digital, was when I heard a friends vinyl set up using a miniDSP active crossover.
I was initially impressed with the out of the box solution from miniDSP, their 4x10HD has a stereo pair of balanced analogue inputs, would handle all my digital input needs and has balanced outputs, which matches my requirements. It comes ready built and tested in a nice 1U height case and would plug straight into my 6 channel power amp. What started doubts in my mind, were a few folks stating the analogue side on the 4x10HD was not as good as its digital and had a higher noise floor. I put the idea on the back burner and continued to read up on the subject and scope what else was available.
I've always liked the gear that Hypex makes and have drawn up a couple of 6 channel amps using their UcD modules, but never got round to building one. I found some good user reviews concerning the analogue side of the Hypex DLCP (DSP) system. It's basically a 6 channel digital Pre Amp/digital crossover, has more analogue inputs than the 4x10HD and all balanced connections. Siegfried Linkwitz tested a DLCP paired with UcD amps on his LXmini speakers. He was astounded how much more low end definition there was and by the overall level of refinement, compared to his 4x10HD and AT1806 amplifier.
The cost of the Hypex DLCP set up, which is only available as a DIY kit of parts needing a case, is the same as the ready built 4x10HD from miniDSP. I was now giving this serious thought and could see the possibility of building a DLCP and my 6 channel UcD180 amp design into a single 2U 19” case of around 300mm depth.
This is what I have in mind, as you can see there are plenty of inputs on the Hypex board, the "set up" USB socket, unlike those on miniDSP, can also work as a USB audio input. It uses all ballanced connections internally as well, to simplify connection with the UcD Amp modules.
I've tried to keep AC/DC/Signal apart, ignore the wires crossing each other, most are on different Z planes, so not touching. Because all the modules were designed by one maker and are meant to work together, there is a lot of design synergy. The DSP board for instance, can be powered from the Aux output on either of the SMPS, used to run the UcD Amp modules. Also the standby function on the DSP board can also send the SMPS's and the 6 Amp modules to sleep for power saving and click free start/sleep modes. This arrangement will give 180w into each of my 4ohm Woofers and 120w into the 8ohm Midrange and Tweeters.
I need to put this into action, limited funds dictates I will build this in two stages. The first involves building just the DLCP set up and a pair of SMPS into the case and using my existing 6 channel Power Amp to run the speakers. The second phase will be to drop the 6 Amp modules into pre drilled locations and connect them to the rest of the DLCP system.