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Black Lion PM8

Passive Summing Mixer By Hugh Robjohns
Published December 2010

The PM8 is an eight‑channel, passive summing mixer, although a 25‑pin D‑sub connector on the rear panel allows a second unit to be coupled, providing 16 mix channels in total using a female‑female parallel cable. The eight main balanced inputs are connected via 'combi' sockets on the rear panel, accepting TRS jacks or XLRs, and each input has its own 10k:10k Edcor transformer — which accounts for a large part of the surprising weight of this unit.

Black Lion PM8Each input channel has its own rotary pan and rotary fader control on the front panel, plus an associated mute button that disconnects the input from the passive stereo mix bus altogether. The output from the passive mixing networks is split three ways. One feed goes direct to a pair of rear‑panel XLRs labelled as passive outputs, and this feed is unbalanced and at low level, so an external preamp would typically be required to restore the signal level, but this does give the option of choosing the gain‑stage sound character. The other two splits are both amplified by solid‑state gain stages to make up for the losses of the passive mixers. One set of outputs is dispatched via balancing transformers (nominal 600Ω types), while the other is presented by dual active output buffers, all connecting through two more pairs of rear-panel XLRs. The master output levels are controlled by two stereo gain knobs. Master 1 controls the output level of the passive and transformerless outputs, while Master 2 controls the level of the transformer‑coupled output.

The PM8 is constructed in a similar way to the AM/CHA1 equaliser (reviewed on page 3058 of this issue). It uses the same compact linear power-supply module, which is switchable for 120/240VAC mains supplies, and has the same worrying chassis‑grounding problem (although the company have undertaken to ground the metal case directly in production units). It also suffers the same haphazardly mounted front‑panel power LED, and employs the same surface‑mount gain‑stage components and the same Edcor input and output transformers.

In use, the mixer does exactly what it says on the box, with the transformers undoubtedly adding a distinct vintage character, which fills out the bass in a very analogue way. Having the option to use an external gain stage, or to take the restored level output via active buffers or another transformer certainly provides plenty of sonic flexibility. The absence of a centre detent on the pan controls is a little disappointing, as is the lack of a unity gain mark on the master controls — but these issues are easily worked around.  Hugh Robjohns

$895 plus shipping.