AshDown Engineering's Superfly Bass amp ...

This is a very cool, well designed bass amp with plenty of power. It has a few peculiarities, though. AshDown was kind enough to send me a schematic and after reviewing it, I understand much better the nature of these peculiarities.

The first of these is that, while rated at 500 watts, this is available as two power amp sections, each having the potential of 250 watts. And this rating is with a 4 ohm load. This load rating is one reason the Bag End cabinets match well with this. These are 4 ohm, 2x10 cabinets with a power rating of 300 watts. I suspect the Superfly rating is one reason some might criticize the unit, as nice 4 ohms cabinets are not that easy to find. AshDown does (or did) have available a line of (seemingly) nice cabinets available for use with this amplifier. I've never seen one of these cabinets except on their web site.

This thing is basically completely digital. The input signal, after passing through in input preamp is presented directly to a DSP-based signal processor. All the tone EQ and compression are handed in the digital section and come back out as analog. It's at this point the DI and effects loops are available. All the inputs at this point (effects in, main signal) are summed together and passed to the digital power amps. Both power amp sections are driven with the same signal, and there is no possibility of adjusting the balance (without voiding the warranty). Such a balance might be desireable if one is driving cabinets with differing sensitivity or if the tonal characteristics of the cabinets might benefit from different drive levels.

The power amps are digital, essentially a pulse-width modulated power supply with a filter on the output side. Each of the power amp sections consists of a pair of amplifiers in a bridged push-pull configuration – exactly as one might see with a bridged QSC or other serious stereo power amplifier.

The construction is very high quality. This alone would justify the original list price. Internal layout is tight. Interestingly, all the input and output signal handing is actually on the back panel. This makes for a very small area to be affected by signal noise radiated from the digital components, once the signals are actually back there.

The Superfly is constructed with an external case having all the decorative elements, surrounding an inner case. This inner case just happens to be a very nice 2U ½ rack size, and the unit is delivered with rack mount ears, though I'd be reluctant to use only these to mount it, as shock and vibration might deform them. I'd probably use a rack shelf (if I could find one that provided for sufficient air circulation) or some kind of rear support.

Strangely quite a bit of heat can be produced. The digital amplifier should be quite efficient and the heat seems to be worst when the unit is sitting idle, so I'm puzzled. This heat may be one reason for the external case providing an air space around the inner case.

The EQ is very nicely flexible. One gets about 20 presets and room to store about 80 more. I started with their presets, modified a little bit and saved in another storage location. The presets seem to be very British. I like them quite a bit. Some of those apparently targeted at thumb work suggest Mark King would be very happy with the sound.

Compression is very simple to manage. They took the easily understood approach of providing a compression setting and one adjusts the impact by setting the input drive level. It can get hissy when this is bumped too much, but even so this isn't objectionable for live use. I'm not sure I'd use it for recording, but I usually DI for that anyway.

One very cool thing they might have done is provide for a stereo return on the effects loop to permit one to drive the power amp sections separately.

I was looking for a light-weight and compact unit for live gigs and this is serving very well.