PowerBass ASA 600.4

A new-school-slab design of extrusion, this amplifier could really do you a mischief if you caught something soft on one of its corners. It has six fins on each side and the layout is classical with power and speaker connections on one end encapsulated grub screw systems and the RCAs and controls on the other. There is no high level (speaker wire) input system but you do get a set of RCA outputs of channels one and two to use to feed another amplifier. Each pair of channels gets a gain control and a bass booster control that can crank on bass up to a full-on extra 18dB at a lower than normal frequency of 40Hz (12dB is a more normal maximum and it’s way extra than ‘one more’) so the brand name doesn’t appear to be piffle as far as obvious design intent would seem to indicate.
Interestingly enough, the PowerBass crossovers are the simpler type but have more controls than normal. (Well I find it interesting.) A regular cheapie crossover-cos-we-can will have a sweepy knob you turn with a small screwdriver for setting the frequency or point at which it works and then a single three-position switch that says high/full/low or HPF/FLAT/LPF or something like that. These channels are given one such switch per pair but also have two frequency-marked pots. One for up (High Pass) and one for down (Low Pass.) This means each is a dedicated highpass or lowpass crossover and rather than switching up or down with the same one, they have one for each function. I suspect that of being what I call ‘A bit of an Issignionis.’ (Sir Alec designed the classic first Mini. Good but made to be sold cheaply. Got him his ‘K’.) This may well be a way of getting cleaner sounding crossovery.
And here’s the top bloke at PowerBass’ response to my question regarding thisthrough the wonders of e-mail and internet publishing.
‘Basically it is more of a design technicality than anything. We lay our own circuit on the ASA amplifiers so I think our engineers have their preferences. Performance-wise as long as quality parts are used, having one or two pots to control the crossover settings on the same pair of output channels makes no difference.’ Generally well made then, and held together with my beloved Allen headed bolts. (Who says reviewers ain’t got preferences? But Allen says ‘posh’ to me. So would Torx, mind and engineering screw type parallel-slotted screw heads are so hoi polloi.)
– Class AB
– 4 x 100w RMS @ 4 Ohms
– 4 x 200w RMS @ 2 Ohms
– 2 x 400w RMS @ 4 Ohms bridged
– Extruded brushed grey Aluminium heatsink printed with model/power rating, brand name deeply engraved
– 8Ga. power terminals (micrometer measured @ < 6mm) with cross headed grub screw bare wire socket connection
– 4Ch RCA input with RCA out for Ch 1 & 2
– 12dB per Octave high/low pass crossovers
– 0 to 18dB Bass Boost @ 40Hz
– Remote phone-type port for wired gain control
– Adjustable input sensitivity: 0.5V to 4V
– Stereo & Mono operation
– Frequency response 20Hz to 22kHz
– Signal to Noise Ratio >94dB
– Channel separation not quoted
– High Pass Filter 40Hz to 250Hz selectable by switch
– Low Pass Filter 40Hz to 250Hz selectable by switch
– Fuse Rating supplied with 30A x 2 (says 2 x 25A in manual)
– HxWxD(mm) 50 x 380 x 240mm
– Complete with sticker
Review by Adam Rayner
PowerBass make some serious bass amplifiers, which is just as well given their brand name. You can find the review of one of their finest Class D jobs in the reviews listing. (This was the amp that I foolishly gave myself a bit of a shock with!) The amplifier has a remote port but when I plugged a control knob borrowed from the big amplifier into this socket, it didn’t power up the knob’s box’s illumination, nor did it affect the sound when I tried adjusting it.
Here’s why, from Mr. Steven Bach at PowerBass USA:
“Regarding the Remote control units on these amps it is hard from me to determine which version amplifier you have and had (XA3000D). Both the XA and ASA amplifiers have gone through several minor updates / upgrades since their introduction. As you already know our Class D comes with a remote control and our AB�s control are sold separately. They only share the same input jack but both are different and meant to do different things. Generally speaking the remotes from the XA series are gain controls and with the ASA the remote controls bass boost. With some versions coincidentally, the remote from the XA will work on the ASA but normally one will not work with the other”.
So yes, you can order a remote to do the bass gain on this amplifier!
I loved the look of the ASA 600.4. Very tidy and purposeful, those hard lines make it look sort of rugged. You simply have to avoid rending your flesh with the sharp corners when installing it. The deep engraving of the PowerBass logo on the top is sexy. Better for being a neat carved geometric font rather than the computer-graphic-controlled router drilling logo engraving found on the top of the Mutant Ascension Four also in this group. That one is meant to look like hand writing, this one looks professional-industrial.
When fired up and pumped with tunes from the guys singing ‘Wha-heeda!’ yet again on the Focal Spirit of Sound # 6 disc, the high frequency detail revealed itself to be well adhered to, if not quite as rare and tinkly as found out of say the Vibe BlackBox Stereo 4. Also, like the MTX amplifier, this one does seem to sacrifice some muscle for the cause of mustering better fidelity. Even more than MTX, these guys do have a response to the need for more bass power (How much you want, Mother?) and this one will be about mids and tops or clusters of coaxials in any normal conceivable heavy duty PowerBass install.
The biggest SPL it could muster was a class trailing 125dB but put into perspective, this is full range and thus seriously unhealthily loud in any case for the testing. However, this slightly-less-than-the-others amount of muscle can be felt in the difference in the weight of the bass between this amp and say the Vibe. These lower frequencies are the greedy ones when it comes to power – that’s why a good subsonic filter is a good idea for all but the very big of wattage and cone excursion. This means that any lack in basic meat will be apparent. It doesn’t impact your chest as much.
The amplifier has a lovely soft touch with the midband, it sounding good on vocals and especially the main melody on keyboards but you can tell the slew rate of the hissy Massive P400.4 just isn’t in there, nor is it as sweet as the Genesis, even becoming a bit tiring if played for long.
I have to admit I liked this one a bit less than some here but it is a gorgeous slab to look at and I love the engraving. I would tend not to think of this one for bass despite its monster 18dB booster circuit and use it to run a bunch of active mids with an active off board crossover myself. Having said that, it is still a lot of amplifier for the money – this is not by any means a ‘bad’ review, even between the lines, it’s just in a market with a lot of product to compete with. Their astonishingly powerful mega-bass products are PowerBass’ Big Story as far as my limited experience shows so far. I’m looking forward to learning more.
This amp can carry its own as part of a whole branded system, which would look and sound pretty damn impressive.
Overall 7.6
Sound Quality 7
Power Output 7
Features 7
Build Quality 8
Value For Money 9