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In het januari 2000 nummer van het tijdschrift 'Klassieke Zaken' werd een artikel gepubliceerd over de ervaringen met de door ons gemodificeerde CD-753 als loopwerk.

CD-speler kent zijn moeder niet meer
door Jan van Gelderen

Het lijkt een typisch Engels fenomeen, maar ook Nederland kent bedrijfjes waar gespecialiseerde elektrotechnici met perfecte oren aan de betere geluidsweergave werken. Uit Zaandam komen zeer fraai gebouwde luidsprekers; Brabant brengt in kunstgraniet gevatte luidsprekers die ook heel goed klinken. De in een pand in het oude Westen van Rotterdam gevestigde firma Audio Products Netherlands levert sinds jaar en dag revolutionair goed klinkende versterkers en goedkope en toch goed klinkende luidsprekers. Thans is daar een cd-speler aan toegevoegd die zijn moeder niet meer kent.

APN haalde een niet slechte, maar ook niet opmerkelijke cd-speler, de Philips CD 753, uit de winkel en modificeerde die. Het resultaat van het hak-, plak- en soldeerwerk in de ingewanden van deze zwarte kast is dat er een cd-speler van de operatietafel is gekomen die wat betreft weergavekwaliteit op zeer eenzame hoogte staat.
Hij is zelfs soldeertechnisch gecastreerd want er komt, door het afkoppelen van de digitaal-analoogconverter, geen spat geluid uit. Middels een snoer dient u hem aan te sluiten op een separate DAC. Behouden is het voortreffelijke loopwerk waarmee Philips zijn spelers uitrust. Dit is de CDM 12 van onze nationale trots. Dat loopwerk vindt u ook in fabrikaten als Musical Fidelity, Technics, Meridian en Marantz.
Op het gevaar af erg technisch te worden moet ik u even vertellen wat er op de snijtafel met patiënt CD 753 is gebeurd, waardoor zijn "things better" gingen klinken. Voor iedere leek te begrijpen is het stuk zwart marmer waarop de speler werd vastgeplakt. Dat maakt ongewenste mechanische trillingen in de blikken kast, zo nadelig voor een goede geluidsweergave, dood. Ook de rijkelijke hoeveelheid teerpapier die thans al het blote inwendige blik aan het zicht onttrekt, dient dat doel.
Vervolgens werd de voeding aangepakt. Een mooie overmaatse transformator met aangehangen elektrolyten en nog wat van die zaken zorgt voor een digitale voeding die met gemak alle gevraagde spanningen levert - zoals een boomvalk achteloos een libelletje uit de lucht plukt - brengt geen enkele klank in ademnood. Alle IC's werden ontkoppeld, het slachtoffer werd van een andere digitale uitgang voorzien en kreeg een BNC-aansluiting. De vier Philipsvoetjes verdwenen in het gescheiden afval; werden vervangen door drie(!) merkvreemde. U weet: een tafel op drie poten wankelt nooit. Gebleven zijn alle door Philips ingebouwde bedieningsfuncties zoals fade, programmering en de afstandbediening.
Dit draaiwerk gaat voor Euro 1245 Rotterdam Oud-West uit. U kunt hem aansluiten op een willekeurige fabrieksconverter, maar met eveneens bij APN vervaardigde apparatuur bent u redelijk goedkoop uit. Een BNC-snoer kost Euro 190, de 24bits DAC van de firma (MKII) kost Euro 2550. Voor Euro 3985 hoort u de celliste hijgen, dat ene jongensopraantje uit het koor in de Mattheüs hartstikke vals zingen en de klepjes van de klarinet plakken. Wij hebben hem in deze combinatie laten spelen.

Op dit moment wordt gewerkt aan een in te bouwen analoge uitgangsversterker. De cd-753 kunt u dan zonder meer aansluiten op uw versterker en gaat Euro 1745 kosten. Wij hebben die versie uiteraard niet getest.

Er zijn meer spelers aan de markt die over dit analytische vermogen beschikken. Deze vermarmerde Philips voegt een aantal zaken toe die ik zelden hoor en zeker niet in combinaties in deze prijsklasse. Drijvende energie in de bassen bijvoorbeeld, niet te verwarren met de hijgende energie, boombas, uit de dertienjarige Golf naast u bij het stoplicht.
Hier gaat het om een laagweergave waarin de bassen niet over elkaar en met elkaar aan de rol gaan, maar om gesepareerde stemmen die een breed geluidsbeeld neerzetten. Neem het nijdige Moderato con moto uit Sjostakowitsj's derde strijkkwartet, een opname van het Borodinkwartet, analoge opname op cd BMG 74321 40713. De bas gromt, de cello slaat en knort en de violen proberen nog wat liefelijks te verkondigen. Een speler die in staat is dat in de goede verhoudingen de luidsprekers uit te slingeren, verdient een 10. Deze krijgt het voor elkaar en dat komt waarschijnlijk omdat het gevreesde jitterprobleem volledig Eindhoven is uitgeholpen.
Nemen wij de proef met het clavecimbel bediend door Gustav Leonhardt (Scarlatti, Sony Classical, CB 601) die mij altijd deed denken aan een rammelende jampot met spijkers. Nu komen de bassen tot hun recht, staan in harmonie met de hoge toetsen. Het gespijker is verdwenen, de muzikale spanningsbogen worden hoorbaar.
Hebben wij de euvele moed het hijglicht van het vergane millennium, Cecilia Bartoli in Vivaldi (Decca 466 569) op te leggen. Mevrouw heeft het fatsoen op haar plaats te blijven, in het midden van het geluidsbeeld, dat overigens veel breder en dieper is dan de luidsprekers bemeten. In deze voor een weergever uiterst moeilijke opname hoor ik voor het eerst dat de hoge uithalen, de bibber in de stem, niets met hysterie maar alles met muziek hebben te maken.

Alles op een rijtje

Hoe werkt dat bij een rijtje solerende zangers en sprekers? Strawinsky's "Geschiedenis van de Soldaat" met van links naar rechts Gérard Depardieu, Guillaume idem en verteller Carole Bouquet (Auvidis V 4805). Iedereen op zijn plaats, in de stem van Gérard (de duivel) precies dat flemende dat ik alleen maar ken uit de grote bioscoopzaal, waar men nogal eens de neiging heeft voor een half miljoen Euro's aan geluidsapparatuur aan te schaffen. En voor het eerst: zonder tekstboekje is de tekst letterlijk te volgen. De weergave van stemmen is fenomenaal. De klankverhouding tussen de voor het orkestje staande viool (Shlomo Mintz) solisten en orkestje is zoals de opnametechnicus het heeft bedoeld.
Gooien we de Wiener Philharmoniker met het Staatsoperakoor en de Zingknaapjes in de cd-la, in Alban Berg's Wozzeck (DGG 423 587) - worden we gefeteerd op een podium breder dan de straat, dieper dan de binnenhof. Alweer is alles te verstaan, zie je de solisten over het podium gaan, zijn koren, orkest en solisten in verhouding. Dit is een speler die opera aankan.
Concluderend - groot orkest, klein emsemble, de menselijke stem - de weergave gaat met een soort onnadrukkelijkheid, gemak en precisie die aanvankelijk verbijstert en vervolgens doet vergeten dat er twee luidsprekers staan waar het allemaal uitkomt. De gebruikelijke handvatten bij bespreking van audio-apparatuur in wat doet het laag, het midden en het hoog, gelden niet meer. Van laag naar het hoogste hoog is geen kleuring te ontdekken, wordt het hele klavier met dezelfde absolute neutraliteit weergegeven. Dat het met aanzwellende ralletendo's en kleine bijna onmerkbare tikjes op het slagwerk ook goed zit, is nu wel duidelijk.
Praten wij over de Euro's, de prijs-kwaliteitsverhouding. Ik ken spelers die veel duurder zijn en minder presteren.

De rest van de keten

Achter de speler hoort een uitstekende versterker en perfecte luidsprekers. Wij draaiden met de P 11 voorversterker van APN (Euro 2995) en sloten die eerst maar eens aan op een dure geïntegreerde fabrieksversterker via de tape aansluiting. Daarmee degradeer je die versterker tot uitsluitend eindversterker. Dit gaf al een enorme verbetering ten opzichte van de oorspronkelijke combinatie wat betreft ruimtelijkheid en definitie van het geluid. APN's eigen eindversterkers de transistor versterker A18 (Euro 2375) en de mono-blokken A 50 (Euro 6075) doen meer recht aan de kwaliteiten van cd-speler en converter.
De A18 is een transistorversterker, in de A50 zijn naast mosfets radiobuizen ingezet. In Sparta aan de Maas doet men niet aan klankregelingen, knipperlichten en geborsteld alluminium kasten. Versterkers worden alleen met de hoogst noodzakelijke knoppen uitgerust. Alles wat je er verder in bouwt, benadeelt alleen maar de geluidskwaliteit, zegt men daar. De kasten verdienen ook geen enkele designprijs: zwart gemoffeld plaatstaal met een lampje. Dat is alles.
De luidsprekers in het programma zijn wonderbaarlijk - kasten van pvc-buis. Vooral de ruimtelijkheid waarmee ze het geluid neerzetten, kan geroemd worden, maar ze hebben meer kwaliteiten. De PMT kost per twee Euro 1475 en de wat grotere AMT Euro 1825.

APN levert - met uitzondering van de cd-speler - alle genoemde zaken ook als bouwpakket voor prijzen die een kwart of een derde lager liggen dan die voor de gebouwde. Men moet echt wel enige ervaring hebben in het bouwen van elektronische apparaten om een bouwkarwei tot een goed einde te brengen.

Artikel over de PMT luidspreker gepubliceerd op de TNT internet site

PMT Poor Man's Tube
One of a range of kit speakers from "APN Audio"
Product: Poor Man's Tube, DIY kit loudspeaker
Manufacturer: APN - NL
Approx. price: 295e/$
Reviewer: Geoff Husband

In this series of kit speaker reviews I've tried to choose models a little out of the ordinary. However in the PMT (unfortunate name that) I've found one of the real individuals of the kit world.

Most speakers, particularly kit's, which have to be easy to construct, are based on a simple rectangular wooden box. The PMT is based on a length of plastic sewer pipe. The thinking behind this is supposed to be that a curved enclosure will suffer less from standing waves as all distances within the enclosure are different. That this is the case is indisputable, though a properly proportioned rectangular box is not far behind in this respect.
No, I suspect the primary reason for using the tube is that it allows for a suitable enclosure that is very easy to construct at a stupidly low price. The question of the price of the PMT is important.
Here we have a very compact floorstander with three drive units a side that comes in at 295e. The kit is comprehensive in a way few others are. It includes everything you need for making up an enclosure - drivers, crossover components, damping materials, fixing bolts, cables and even glue! Once complete the PMT just needs a coat of spray paint to finish. When put next to the hulking shape of the IPL S3MTL's (see pic) which cost only a little more, they look very poor value. But add up the cost of the IPL's cabinet and finishing not to mention man hours, and their price goes up to at least 50% more than the PMT's.
Though much of this low cost is accounted for by the enclosure the rest is obtained by use of cheap drivers. The PMT's use two tiny bass/mid drivers a side. These are from Tesla and are the sort of thing you see in better computer speakers running "full range".
This means that they're made in their tens of thousands and are therefore "cheap as chips"... The fabric dome tweeter is likewise a pretty cheap affair but at least a proper tweeter for all that. All drive units have substantial magnets, the bass/mid units having thin pressed steel frames but all are shielded.

Construction

Supplied with the kit are two lengths of sewer pipe cut to length, a piece of high quality birch ply cut to size for the baffle and three circles of MDF. Building the enclosure from this is simplicity itself.
The first job is to glue two of the circles together, one is larger to form the base the smaller fits tightly into the tube to seal the bottom, but this is done later. Next the large slot in the tube is cut to take the baffle. There is no guidance on this and it can be tricky...
Finding a true perpendicular line down a tube is not as easy as it sounds, but luckily each tube has manufacturers writing running down it and this make the perfect guideline.
Next you have to work out the width of the slot. Here the suggestion is that you cut a template from paper and draw round it. Now the obvious way of doing this is to trace round the baffle and cut out the shape to make the template.
If you do this the slot will be much too narrow! Obviously the tube has a curved surface, the baffle a flat one - it don't work... You need a pair of callipers to measure the width of the baffle then transfer this to the tube and mark out. Doing this the slot was perfect, needing no filing at all.
Really APN need to address this by giving at least the dimensions for a paper template. Once the marking out is complete drill a hole in each corner and cut the slot with a jig saw.

Next comes the preparation of the baffle. Here you need to cut out the driver holes and fit the captive nuts for the driver fixing bolts. All basic jigsaw/drill work. This assembly is then just forced into the slot - the tension will hold it in place, and glued by spreading loads of the supplied 'rubbery' glue to make the baffle airtight.
The snag here is that in cutting the slot you end up with a 90-degree surface on the cut which leaves a rather ugly gap where the baffle fits. There are two solutions.
Either file the cut surface to the correct angle, or if you have access to a router, cut a V-shaped groove along both vertical edges of the baffle which the sides of the slot then clip into.
This is what I did and I'd strongly recommend APN to supply the baffle slotted like this. It makes a very neat join and the slot can be filled with glue (see pic) ensuring an absolutely airtight seal.
Once the router was set up it took approximately two minutes to do both baffles so I can't see it effecting the price and it makes assembly much easier. However before gluing up it's best to spray the enclosure and MDF circles. I also waxed the baffle, which took five minutes and was all the finishing it required.

All that is left to do is to glue the top circle of MDF into the tube and push fit the bottom circle/base to complete the enclosure. I've made many speaker kits, but this one took a total of two hours to compete both enclosures, nothing else comes close!

Having made sure it all fits OK it's time to solder up the simple crossover. This is "hot-melt" glued to the bottom circle (see pic). The kit includes some proper speaker wire and this is all soldered up to the drivers and down to the crossover and thence to the high class binding posts supplied. With the IPL kit there was supplied a simple drawing of the crossover soldered up. This might be an insult for anyone with decent knowledge of circuit diagrams, but for those whose knowledge of electronics could be written on a drawing pin with a pneumatic drill (i.e. me) it would have helped to have had a similar drawing with the PMT's.

A few minutes to make up gaskets for the drivers and they can be bolted up and the base+crossover push fitted - NOT GLUED in place. Allowing time for glue to dry, anyone will be able to put these speakers together in less than a days work, perhaps even a morning...
The base is not glued until you are sure all works as it should do, because once glued you have no access to the crossover at all. This certainly made me nervous as dry joints and the like often show up late... The kit comes without spikes, and the thin base would make them tricky to fit, but three blobs of blue-tack nailed them to my granite slabs to very good effect...

The results!
New speakers generally sound pretty poor when first fired up and the PMT's were particularly bad in this respect - they sounded like a transistor radio, and a cheap one at that. Thankfully those little cones took very little time to break in.

Given about 10 hours of music they started to sing. Their one outstanding quality is their imaging. Tiny floorstanders with very narrow baffles and low colouration cabinets should image well but these were exceptional. I'd go so far as to say they bettered even the Cabasse Sloops in this respect - no mean feat considering the Sloops price (1,500 pounds) and hi-tech dual concentric drivers.
The PMT's generally light and airy presentation helps give the soundstage space, but in it's width and depth it really set a reference point in my system.

You wouldn't expect such a small speaker to produce deep bass but what it does produce is tuneful and fast, the sealed box providing a smooth controlled roll-off, wall re-enforcement helping here.
Next to the IPL's they lacked anything in the way of low bass but those tiny drive units still surprised further up. The midband was clean and open, hence the imaging, with good detail retrieval. At the top end things were a little less happy, the tweeter being "spitty" at times, certainly with female vocal syballents, Cymbals a little 'splashy'.

There is a certain implication on the website that the PMT's are suitable for low powered valve amps. Quote "The frequency response is 50 Hz - 18000 Hz and sensitivity is over 90 dB's. A simple 8 or 10 Watt amplifier will thus give a sufficient sound level".

I'm sorry but this isn't the case unless you listen to gentle music in a cupboard.
Efficiency is quoted at 90+ db's but I suspect that is pretty optomistic, I'd say a more honest figure would be 87-88 db's. In addition the impedance curve, though commendably flat, resolutely sits at 4 ohms. My own 30 Watt Audion valve amps managed to get reasonable levels in my 6x4 metre room but only when connected to the 8 ohm tap. Using the 4 ohm tap reduced levels considerably though the sound filled out somewhat.
No SE valve amp with a baker's dozen of watts is going to be happy with this. Likewise absolute sound levels are inevitably limited though it surprised me how much abuse those little cones could take, coaxing out a surprisingly dynamic performance with rock music and classical alike...

Conclusion
Here we have a very cheap kit, certainly the cheapest floorstander that I have come across. It uses cheap drivers and a very simple to construct cabinet. In its favour, the kit is complete and an absolute doddle to build. However I do see the PMT's as something of a niche product sonically. In some respects they are outstanding, their imaging is simply superb and a well judged midband brings out the best in small-scale music. What they don't do is "scale".
Limited maximum spl's and restricted bass mean they founder during big orchestral climaxes or rock anthems. To be fair I'm sure that this is precisely how they were designed. For jazz, female vocal and lighter classical works they are ideal, particularly where space is at a premium where they will not excite a small room, yet produce images that seem to demolish the wall behind them.
For those looking for an AV system I can imagine that four of these with a suitable subwoofer would manage that rare feat of producing decent hi-fi as well as surround sound.

Comments from the manufacturer
We are very glad with this article published on one of the finest websites in the audio world. But ........ there are some comments to be made!
First of all the tubes have thin walls and are not made as "sewer" tubes but
for air conditioning channels.
The circular form has the advantage of superb strength in horizontal directions.
Furthermore PVC is a "thermoplastic", i.e. it converts pressure to heat. In loudspeaker cabinets these advantages mean that very few additional sound is produced by the cabinet so the coloration factor (from the cabinet) is low.
A motorized jigsaw can saw with an angle. In this way you make a perfect fit. I strongly oppose to the "V-shaped groove". The advantage of a circular form connected neatly to the front of the baffle is that "diffraction" is kept at low level. Hence the stereo imaging is better. With the groove the units "see" an obstruction at the sides which will add diffraction.
A 'closed' cabinet lacks bass power in the lower octaves. But a closed cabinet dampens itself, there's less need for damping from the amplifier.
Most tube amplifiers have relatively high output impedances and therefore few damping. A closed cabinet also adds much less bass harmonics then "open" systems do.
The PMT is 4 Ohm and will perform nicely with tube (or transistor) amps of 20 Watts and up, although we demonstrate them with a 12 Watt SE design, no problem there!
Many thanks for the opportunity.
John van der Sluis

NOTE by Geoff Husband - The V-shaped "slot" I routed in the baffle was right on the edge and only the depth of the plastic pipe's cut surface. As a result the transition from tube to baffle was perfect, easier to make and far stronger - I still consider this to be the best method of construction. With respect to efficiency, APN will hopefully alter the quote on their website.

Copyright 2000 Geoff Husband - http://www.tnt-audio.com

Product: Hawk Audio MP-DAC
Manufacturer: APN / Audio & Techniek, UK distributor
Approximate price: 1160EU (built) / 775EU (complete kit) / 615EU (without housing and bits)
Test sample: loaned from manufacturer
Reviewer: Werner Ogiers

In commercial terms a pretty unsuccessful magazine, but, linked to this, also a pretty good magazine. Essentially a bunch of audio and electronics engineers part-time performing as journalist (among them Peter Van Willenswaard, who once in a while appears in Stereophile, and IMHO still one of the best audio reviewers walking this planet). Concentrating on the basics, and therefore - uh - with a shoddy mag layout, with black and white pictures, even with bad typography, all in a charming atmosphere of amaturism (remember your Latin: that word stems from amare).

Oh, and with a rather critical stance. A very critical stance. A stance that would even scare the HP sauce from our own Thorsten's sauerkraut. Which is fine, as APN always backed their attacks on commercial audio components with a host of self-designed amplifier and speaker kits that one after the other got an enviable reputation for pure quality in the Benelux. Small wonder: which other audio magazine offers internships to engineering students to design a new component or to research some aspect of auditory perception?

Other mags talked specs, A&M told us that stereo was supposed to have depth, A&M told us that sound reproduction had to have musicality. Other mags hailed CD (it was 1985), A&M went to Sony/Philips/Akai and simply told them in the face that CD was crap. Not that this avoided the inevitable. The established magazines in the Benelux all reverted to a critiqueless babble, and A&M disappeared. Don't we all know such stories?

All that's left now are a website with the occasional interesting techno-article or component review. And the kits. Of course the kits. Since about a year now these kits are available world-wide, so time to take a closer look at them.

Personality crisis
Believe it or not, but APN-shaman John van der Sluis (interviewed by Lucio here) contacted me for a review of the MP-DAC right when I was considering buying his A-18 class-A zero-feedback amp kit.
And since right at that same time a Dynaco ST-35 valve amp crashed on our doorstep anyway - Christa almost tripping over it - the A-18 plans went into the fridge, and the digital-analogue convertor was sent in from Rotterdam.

Halfway the time alotted for this review, the product brand name was changed from APN to Hawk Audio. They couldn't resist, could they?

The machine
To the outside world the MP-DAC (Marco Pol DAC, referring to its designer, not to the Venetian explorer of post-medieval China) is a very simple device. No power switch, one coax digital input on BNC, and one set of analogue outputs. No reason to waste any more bandwidth/time/paper here.

The ghost in the machine

Conceptually this DAC's inner sanctum is very simple too: the digital stream arrives through a custom-made pulse transformer and a Crystal CS8412 input receiver, then is converted in a CS4390 DAC, followed by discrete analogue filter/amplifier section. That Crystal DAC chip is the same as is used in, for instance, Meridian's 508.24 CD-player. It is a delta-sigma (bitstream) device with a theoretical resolution of 24 bit, although in our world real 24 bit performance is beyond the possibilities of physics, unless time-averaging tricks like in the dCS RingDAC are employed, of course.

While the CS4390 features balanced-differential voltage outputs, the MP-DAC uses only one phase of the signal: this may compromise dynamics and internal common mode noise rejection, but allegedly the designers have tried all possible configurations of this chip, eventually settling for the solution with the best sonics.

The analogue section is curious in the sense that it is an adaptation of the A-18 power amp's voltage gain stage. So we are looking at a fully discrete, symmetrical, zero-loop-feedback class A amplifier, running off +/-30Vdc supplies, and with only two 2-transistor stages in the direct signal path (should something like a 'direct signal path' exist).

The filtering of out-of-band signals is done fifth-orderish, with a passive RCRCLC-section after the DAC chip, and a single RC filter at the output of the amplifier. All signal capacitors are nice polystyrene film-and-foils, bar one 3.3uF Audyn metallised polypropylene for coupling purposes.

With the DAC chip and its on-board voltage-output opamps a given, about the only thing one can do to coax better sonics from something like a Crystal CS4390 is to feed it a nice and clean supply voltage. Well, these APN guys are serious about their nutrition. Deadly serious: Two 30VA Amplimo toroids, one for the digital board inclusive the DAC, the other for the analogue board. Four rectifier bridges, damped with series resistors. Six series regulators (317s, 337s, 7812s and 7912s), and six TL431 shunt regulators. APN claim an ultra-high regulation bandwidth for the latter (which I find a bit dubious, as the bandwidth of a 431 operating with some gain is a mere 20kHz or so, but OK, kudos to APN for using these unusual devices which probably beat your average 317/337 every time of the day).
The overall capacitance reservoirs distributed over the whole DAC amount to 60000uF: that's more than my power amp can boast. Individual stages each have their own clusters of filter capacitors: big elcaps including Elna Stargets and Sanyo OS-CONs, Wima and Siemens polyester films, and then Sibatit ceramics for the highest frequencies. Before you go into a frenzy over all the possible parasitic resonances such contraptions can produce: the designer says he verified the real-life behaviour of these combinations.

No effort is done to minimise jitter, apart of course from feeding the digital circuits a clean voltage. The MP-DAC relies purely on the Crystal receiver's PLL to keep things in pace. For connections the APN people specify a decent coax, with BNC connectors, as RCAs "cause reflections due to mismatch". Which leaves me wondering about the mismatch caused by the solder terminals and the circuit board that coax is connected to? Never mind ...

From a technical point of view the MP-DAC is a very nice piece of work, something into which has gone a great deal of effort to optimise the analogue section and the power supplies. And both these aspects make it rather unique in a digital audio realm where tiny transformers, cheap IC opamps, and uninspired textbook "engineering" still are the norm.

The question
Now I can hear you mutter: What's the point in offering a DAC restricted to the standard 44.1k/16 CD format? Very easy question, although marketing droids and audio magazines, the villains, would want you believe otherwise.

There is no alternative format. Oh, 96kHz/24bit DACs do exist, and there is even the odd 192kHz compliant component out there. But there is no real consumer format available to benefit from these DACs. Take DAD, entirely embedded in DVD-Video. Yes, it is high-res audio. But not backed by the software community it will prove to be still-born, and further, the DVD players that really output a digital 96kHz stream on their S/PDIF port are 1) scarce (only Pioneer does this) and 2) quasi-illegal, as copy protection issues haven't been settled yet by the powers that be. In short: why bother?

The powers that be. They like a tough game. Competition's good for you. The powers that be. They pick horses for courses. They're the market forces. (Radio KAOS, Roger Waters. Who else?)
Then there are DVD-Audio, and of course renegades Philips' and Sony's SA-CD. Both hi-res. Again, both not legally enabling a full-resolution digital output stream. And if either of them, in the future, will have encrypted etcetera digital outputs, it will not be over the S/PDIF interface used by the DACs you can buy now. It will probably be over IEEE1394/Firewire, perhaps over USB or USB2. And believe me, the chances that DAC-vendors will offer retrofits to their older products are pretty slim: just look at the additional cost and complexity of, say, a full Firewire node.

The final source for high data rate audio is "upsampled" CD. If you believe in fairy tales, that is: what is lost remains lost. Otherwise we would have post-tax salary upsamplers (writing this from Belgium, with an over-50% ripoff, OK?). The only thing upsampling, itself just a fancy name for oversampling, buys you is that it enables you to use a new hi-speed DAC with a data rate slower than the one it was optimised for. And if that DAC happens to sound a little bit better, so then may your CDs. But I believe it is more a case of "different" than of "better"2: the upsampling process modifies the original data. It doesn't add information, and it changes, it has to change mutilate?), what there is. Hardly a valid option, but think of it, it does enable the high-end industry to sell you a few more boxes.

So, given the dearth of valid hi-res sources, and the abundance of ordinary CD software, there still seems to be a role for a 44.1kHz/16bit DAC. At least: for a good 44.1kHz/16bit DAC.

The ghost building the machine
Contrary to for instance the Parts Connection's Assemblage DAC kits, this one really is D-I-Y: you have to do everything, with as sole exception drilling out holes in the housing. So be prepared to stuff three PCBs with a couple of hundreds of components. Luckily these PCBs are very well made and of a good layout, with solder masks applied.
Still, given the overall complexity I would not advise this kit to anyone with only basic soldering and electronics skills. APN claim construction will need about 10 hours. I spent about 20 hours soldering, but then I took my time, and especially in the analogue sections I took care of hand-matching components for optimal channel balance. Problems? No serious ones: My 15W Ersa home iron was not quite powerful enough to do the three or four solder joints that are embedded in massive ground planes. I had to revert to Low Melting Point silver solder to get these correct.
If you have access to a temperature-controlled soldering station you'll fare better. (We have Weller stations at the lab, but I did not care for the paperwork required for checking-in the MP-DAC - in N loose parts - at said over-secured location: Nosir, this is an audio component, Sir, not part of a new superconducting computer I'm trying to steal, Sir.) Further the holes drilled for the Elna Starget caps in the analogue section were too small. Not wanting to re-drill, as this could have wiped away the throughplating, I just blue-tacked the Elnas to the PCB and directly soldered their leads to the top of the solder pads, SMD-style. A few holes on the power supply board were undersized as well, but this board is single-side and hence could safely be re-drilled. I understood from APN that a new version of the PSU board is shipping now.

While previous MP-DAC incarnations came in a grey 19" housing, looking a bit macho, and with undeniably a low domestic acceptance factor, the device tested here came in a custom black-lacquered 44-cm wide case which is a bit boring (heck, they initially forgot the copper name plaque!), but which matched my Michell gear well (must be the colour), while vaguely reminding me of Sphinx electronics. Funny: Sphinx is Dutch, and good-sounding, too. As for the fit and finish of this housing: the latter was excellent, and the former, well: suffice to say that it required a bit of creative input on my behalf to make it do what it was intended to do.

After the work, the fun
As you know, my regular CD-player is the Rega Planet. I bought one a couple of years ago, shortly after I wrote one of the very first published reviews of it for Audio Vision (in fact I think only What Hi-Fi beat us). I chose it because in a group test of similarly-priced players it was the only one to sound natural, as opposed to synthetic, and this without any trace of grain. Of course, the Planet isn't perfect. It tends to be a bit small-scale, and detail and air lack a mite, giving a vacuumed-background effect.
But these are small prices to pay for that naturality, especially at the Planet's low cost. And of course it behaves like a digital audio product: good discs can sound utterly wonderful, but all too often the sounds regenerated can be lacking in interest, in involvement. That's why the Planet is mostly used for background music, while the GyroDec is only used for serious listening. Serious, thus more fun.
Still, together with the Marantz CD-17 the Planet is one of the few CD-players I really like, and I found it to work nicely with preamps costing up to 3000EU.

Having finished the MP-DAC I switched it on, connected it, and verified that everything worked as it was supposed to do. It did. Knowing I shouldn't listen, I did. First impressions? This DAC instantly reminded me of the sound I got with my turntable and the Mistral Phonostage (reviewed here). But forget this, first impressions being what they are, I left the DAC on for a month, only using it for background music.

And it changed, during that month. David Sylvian's victorian jazz masterpiece Secrets of the Beehive betrayed the excellent low-level resolution of this DAC with subtle cymbals and natural, easy-to-follow decays, in a wide-enough and, above all, deep soundscape. That image depth is accentuated with vocals placed solidly in front of the speakers: placed forward, yes, but this in a gentle and relaxed way, as opposed to in-your-face.

Tonally the MP-DAC is off-a-piece, admirably consistent, merging a rolling and fruity bass with creamy mids and a truly sweet treble. Loreena McKennitt's The Visit can sometimes sound a bit thin, but not here! Likewise, my beloved Monteverdi recording of the Maria vespers (Archiv, Gardiner) never before sounded so believable, so complete, the choirs made up of almost-real people, singing in a really cavernous and complex acoustic that as a warm velvet cloak enveloped the listener (lucky me).

Positioning of sound sourced is a bit soft-focus, not as precise as modern transistor-based high-end amplifiers and CD-players tend to do. In addition, the texture of the sound was ever so slightly roughed-up, more like wood au naturel than, say, like polished steel. According to my experience both these characteristics tie in with the use of zero-feedback circuitry, and indeed the MP-DAC's sound resembles for instance the electronics of LFD/Mistral and the Kora amplifier I tested recently: all zero or low-feedback designs. And both these aspects should be contrasted to the more spot-lit, more sheeny, higher precision of conventional designs. Precision? Or apparent precision?

The amount of detail present, and especially the low-level resolution make this DAC emminently suited to late-night listening: even at feeble levels all of the music was still there, and this was the first time I could listen to the ethereal choir in Holst's Neptune without headphones, or without blowing up the speakers at the start of the subsequent - much louder - piece simply because the source demanded a ludicrously high listening level in order to help it pretend having anything like decent resolution. Well, the MP-DAC has it, resolution, and this makes things sound rather lifelike, be it the resin of Yo Yo Ma's cello (Insired By Bach - The Cello Suites), or the way the 'Cha cha cha' is sung by the backgrounders in Ruben Gonzalez' rendition of La Enganadora.

So all was well then? Of course not: perfection does not exist. Overall I found this DAC a little bit restrained. Perhaps because of a certain politeness during louder passages (then again, it did kick some ass with Hole, with the Walkabouts, and with the bass hammer in Tori Amos' Space Dog intro), or because of the warm, dare I say dark, tonal balance. However, to me this is not much of a problem: I'll take any time of the day a dark and musical component over a bright or neutral and overly analitical one. Moreover, one should not forget that this is a kit, and that it is an interesting property of kits that they can easily be tweaked (a just as interesting property of kit-builders of course being that they know how to do that tweaking bit), either by decreasing the action of the output filters, or by component substitution. But one shouldn't even go this far: substituting an ultra-short Deskadel interconnect (right, one of the few Belgian hifi products!) for the AN-V slightly opened-up things, whereas using a Marantz CD-52SE for transport gave the impression of a darker result, although here I could easily have been deceiving myself.

Conclusions
The MP-DAC is not a simple beginner's kit, and neither is it a particularly cheap one. But its sound is relaxed and warm, dynamically perhaps a bit polite or muted, but admirably consistent over the whole frequency spectrum, and with excellent low-level resolution and imaging.
So far this is one of most musical digital sources I have encountered. Furthermore, it is unfussy and should not pose much compatibility problems with other gear. Recommended.

System used

CD-transport: Rega Planet, Marantz CD-52SE
Digital interconnect: Sonic Link with BNC connectors
Interconnect DAC -> preamp: Deskadel I-1, Audio Note AN-V, Prefer MGK-226
Preamp: Michell Argo/Hera
Power amp: Quad 306
Loudspeakers: Quad ESL-57 on Target stands

Copyright 2000 Werner Ogiers - http://www.tnt-audio.com

Werner Ogiers also wrote an article about his experiences with our A-18 amplifier. It can be found at TNT!