Diamond Audio D1 300.4

15th May 2008 Adam Rayner

Along with the Clarion APA 4360 this is one ridiculous slab of amplifier for what used to be solely the price zone of Purple Throbbing Monsters from high street electronics nerds’ shops Maplins. Only now you can get this thing for two hundred smackers UK. Descended from some of the best sounding amps for cars ever made.
It is a simple extruded heatsink design with the classic layout of controls and signal entry one end and speaker and power connection the other. The terminals are the enclosed metal billet type with clear insulation housings and Allen headed grub screws. They are not gold plated. A large Diamond Audio silvery ‘swoosh’ and brand name marker are stuck on the top of the heatsink and on the far end the RCAs allow for four channel input as well as offering another pair for link signal out. There is also provision for high level input by way of two multi pin connectors for which corresponding loom plugs are supplied.
Each pair of channel has a single filter that can be switch selected to be used as Highpass or Lowpass or else off and rather than a seriously potent amp-crippler of a bass boost control, you get a simple switch that can boost the lows up by a single 6dB step at a slightly higher than normal 50Hz. The filters can be set between 40Hz and 400Hz. The ends are finished in a sexy black moulding with a neat D1 300.4 badge inset into each end.
The whole package is not bling but is handsome in an Old School sort of a chrome and black fashion.
– Class AB
– 4 x 50w RMS @ 4 Ohms
– 4 x 75w RMS @ 2 Ohms
– 2 x 150w RMS @ 4 Ohms bridged
– Extruded Aluminium heatsink with black anodised brushed finish and Diamond logo and swoosh in large chromed 3D on the top
– 8mm diameter 4Ga. power terminals with Allen headed grub screw bare wire socket connection
– 12dB per Octave high/low pass crossovers variable 40Hz to 400Hz
– Zero or +6dB Bass Boost switchable @ 50Hz
– Input sensitivity: RCA level 150mV to 4V and high level 1.5V to 14V
– High level connection via dual multi pin sockets looms supplied
– Gold plated 4Ch RCA input and 2Ch output
– Black polymer end caps secured by black Japanned Allen headed bolts
– Stereo & bridged operation
– Frequency response 20Hz to 20kHz
– Signal to Noise Ratio >95dB
– Channel separation 50dB
– Fuse Rating 25A x 2
– HxWxD(mm) 58 x 354 x 216mm
Review by Adam Rayner
It does seem a shame that Diamond Audio are no longer offering some of their more rare-breed style mad end products but when you see why there is no wondering any more. The amplifier here is so much better than some of the others at the same price point it makes you realise that expertise is really not as thickly spread out with amps as it is with headunits. There are still lots of smaller brands that have got some incredible amplification electronics and they have got most of the mainstream by the throat when it comes to sheer quality of results.
I cannot pretend to know how or why this is so because you would have thought that the likes of big multi-national companies should be able to get this level of expertise into their amps. In the death it has to be things to do with economies of scale and large scale manufacturing issues as the volume of the product may not be anything like what the likes of Clarion turn out. Which is complementary to them as their APA4360 was the closest that came to matching this amplifier for performance. Again, I accuse this amp of being offered up at a narrow margin from the UK distributors AVHQ as it could easily support a ï¿½250 price tag in more normal times. Right now with competition so serious it is the buyer who benefits as this is proper classy and seriously potent for relatively little outlay.
The crossovers are delicious and are smooth in sound, steep of slope in effect if not by simple specification and easy to use. Again the moment it was fired up, it revealed its class. My notes read ‘lovely impact and awesome detail.’ So this amp is punching right up and out of its weight class. It’s simply badder-assed and better sounding. Lovely approaching high end with all of the muscle that the Kicker can muster and all the refinement of the Clarion with its own overlay of better, faster rise time sounds and a generally enjoyable feel. It raised Cain, too with a fat 124.5dB registering on the AudioControl SA-3055’s SPL meter.
I did manage to pull one of the RCA’s outside sleeves off with a too tight plug but it pushed right back into place and along with the small red ring of plastic that is used in these parts to denote the channel, it reassembled perfectly to form interference fit with the earthing conductor within. However, you might want to be careful as this amp will tend to attract buyers likely to use better quality RCA cords and so more grippy plugs.
All in all an incredible bargain that offers some real performance at an entry level price, scoring highly enough for its sound, build and mad VFM to garner a Talk Audio Recommended flag.
Overall 8.8
Sound Quality 9
Power Output 8
Features 8
Build Quality 9
Value For Money 10