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Hawk Audio MP-DAC MkIII

Review by Tony Moore, 24th November 2001

I finally decided to purchase the Hawk MP-DAC after reading reviews of both the MP-DAC and Audionote's Dac 1.2. The deciding factors for me were the use of a more sophisticated D/A device, the obvious care in the power supply design and the fact that the kit looked more of a challenge to build!

Delivery was prompt and the unit extremely well packaged with plywood panels in the box to protect against puncture. Each section of the build was bagged separately, making it easy to check through the parts list and verify that all components were present. In my case I had just one incorrect item, an electrolytic capacitor that was the wrong value. An easy mistake considering the size and colour were very similar. An email to APN later and I was promised a replacement capacitor by return of post.

The MP-DAC uses double spade terminal pins for the connections to the three printed circuit boards. I found these difficult to fit, requiring the use of a hammer and more than a little force! However, perseverance paid off and I realised at a later stage just how useful these tags can be when wiring between the pcbs!

There are a large number of components in the kit but as mentioned earlier they are bagged according to pcb and are easily identified using the parts list. The instructions consist of a general section and one specific to the MP-DAC. There is some really good no-nonsense advice contained in the general section and this can be applied to any electronic project.

One small criticism I could make is the lack of component pin-out diagrams, which although not strictly necessary, allow a greater level of confidence and involvement for the builder when the component orientation can be checked during placement.

I fitted the components to the printed circuit boards according to the board complexity. The power supply first, then the digital board and finally the output amplifier. The two latter boards are double sided and through plated. These boards are of a very high standard and quite high density in terms of components. A fairly good standard of soldering is a must. A reasonably high powered soldering iron (preferably temperature controlled) is also required since a number of the solder pads are on large ground planes and suck much of the heat away from the iron. A degree of delicate finger work is also required with the polystyrene capacitors as I found out to my cost when one broke apart whilst I was bending the leads! (Replaced without question by APN)

My initial power-up went by without problems, power supply voltages were all within the ranges specified in the instruction booklet. Unfortunately a problem presented itself upon connection of the psu to the output amplifier board. One of the power supply voltages in both channels of the amplifier were much lower than expected. After much experimentation and head scratching I began to suspect that two of the resistors were incorrectly placed in the regulator circuits. An email to APN was sent at 01:30 asking for assistance!!

It was with great surprise that I got a telephone call first thing the following morning from John van der Sluis himself in answer to my plea for help. He agreed with my assessment of the resistor misplacement because of a mistake on the parts list. The offending resistors were duly swapped and this fixed the power supply problem.

Finally the moment of truth arrived. The MP-DAC connected to my CD player and amp and power applied! What? Only one channel? There were beautiful sounds coming from the left channel but total silence from the right! Some further investigation revealed that the output muting reed relay was faulty and not opening it's contact. Once the relay was removed from the circuit both channels made their presence felt.

The initial sound quality was nothing short of superb. Although slightly harsh and unfocussed throughout the frequency range it was far superior to my CD player alone. I left the MP-DAC powered up with a signal continuously and even after just 24 hours the stereo image had improved greatly and the harshness replaced with a sweet treble. The sound continues to improve as time goes by, only one week so far of the four weeks recommended by APN.

I've listened to both CD and also to DAB radio (which uses a 48khz digital signal) and both sound very natural. I'd have to say that an attribute of the MP-DAC is improved bass and treble response. The overall sound more closely resembles vinyl than what I've come to expect from CD. It's by far the most significant improvement to my Hi-Fi system since I changed over to valve amplification.

In conclusion I would recommend this kit to anyone with a reasonable aptitude for soldering and electronics. The kit itself is well documented and to a high standard. The support from APN is superb and timely. I had my replacement capacitors and reed relay very quickly even considering the normal postage delays from Holland to the UK. The kit presents enough of a challenge to be interesting, yet has few pitfalls for the unwary.