Summing Mixer

Mixers

Published November 2024

With 18 inputs and bags of headroom, this new MixDream aims to keep high‑quality analogue summing simple.

SPL’s MixDream XP Mk2 is a Class‑A 1U rackmount mixer with 18 line inputs, fed to it through a pair of (Tascam standard) DB25 D‑sub connectors and a pair of XLR connectors. Like SPL’s other products, it’s manufactured in Germany and, as with other SPL gear I’ve used, the construction quality of the review unit was immaculate, inside and out.

Features

The 16 DB25 inputs are organised on the front panel as eight pairs, the left‑hand eight channels having four latching buttons to switch each pair between dual mono (both signals are routed to the left and right buses, putting them in the centre) and stereo (the odd‑numbered input goes to the left bus, the even‑numbered one to the right). The eight channels on the right always operate as stereo sources (odd channels to the left bus, evens to the right again), and each pair has a latching ‑18dB pad button; SPL suggest this is to allow you to send hotter signals from digital devices/plug‑ins, such as reverbs, for “higher digital resolution”. There are no individual level or pan controls for these channels; the focus of this device is very much on simple, high‑quality summing. The electronically balanced XLR Expansion input, activated/bypassed using a dedicated button, accepts the stereo output of another device, typically a mixer for more inputs at mixdown; for example, you could daisy‑chain two MixDreams. But you could alternatively feed it any line‑level signal.

As well as the pair of DB25 sockets, which cater for 16 input channels between them, there’s a switchable stereo expansion input on XLRs, taking the total input count to 18.

Another central button, labelled Variable Output, enables an output gain control (‑10dB to +5dB; when not engaged, the mixer sums at unity), so you can optimise the level for the next device in the chain. There are two separate stereo line‑level outputs on rear‑panel XLRs, a main mix out and a monitor output. Wired in parallel, these electronically balanced inputs deliver the signal post the output gain control. An IEC power inlet, its associated rear‑panel on/off rocker switch and mains voltage slide switch, and a ground‑lift button complete the I/O and user controls.

Inside the device, the audio rails operate at ±30V, so there’s bags of headroom, and although the specifications in the manual could be more informative (eg. we’re told there’s 10Hz to 200kHz frequency response, but with no reference) they do confirm a high technical quality, with low noise, distortion and crosstalk and decent common‑mode rejection.

The output level can be boosted or attenuated using a front‑panel gain knob.

Sum Great Reward?

I hooked up the MixDream XP Mk2 to my patchbay and fed it various signals from some DAW projects, both ‘as is’ and processed by outboard gear. I don’t really buy into the practice of breaking a DAW mix out of the box just for analogue summing but it makes sense to me to capture a stereo mix when lots of signals are already coming out of the box; it means fewer stages of A‑D conversion.

It sounded just as good as I’d anticipated: musical, clean and effortless, with no discernible noise or distortion, just as analogue summing should be!

Subjectively, it sounded just as good as I’d anticipated: musical, clean and effortless, with no discernible noise or distortion, just as analogue summing should be! Though reassuring to know hot signals could be accommodated I didn’t have need of the pads. The expansion facility worked well: I plumbed in my Dangerous D‑Box to give me 24 inputs in total, and noticed no degradation. The output level adjustment was handy, with just enough range to set how hard the mix drove a stereo bus compressor. I occasionally wished for more facilities, such as LCR panning for the mono inputs and a pre‑output insert point so stereo bus processing could be monitored but, to be fair, SPL do offer a more feature‑rich summing mixer, and I generally felt that I had what I needed. That the status of all the controls was really easy to see at a glance is another positive that shouldn’t be overlooked.

In short, then, this is a high‑quality summing mixer that’s easy to use. If you’re in need of a high‑quality summer without lots of ‘extras’ it warrants a slot on your audition list.