Oh and a humble looking Cambridge Audio phono stage.. Heavily modified..
Some people just care about the sound and the price. Actually, that’s probably most of us. There are others that care about why things sound good and seek ways to improve what they already have. Very occasionally you chance upon someone in the latter camp that actually knows what they are doing, and is prepared (for a modest fee) to upgrade your hifi and return it to you better than ever. Enter Jez Arkless of Arkless electronics.
I’ve been down this road a few times with other modifiers and the results have varied from downright disappointing to startlingly good. However, Jez’s modified Cambridge Audio phono stages have been getting rave reviews from our cousins over on Pink Fish Media, also I owned an unfettled 640p until quite recently and was very pleased with it. In fact I always considered it a bit of a giant killer in its own right. So when Jez emailed me, asking if I wanted to have a play with one of his reworked examples I didn’t have to think long about my answer.
I will link to the technical stuff a bit later, but here’s the deal, you buy a Cambridge Audio 640p or 651p, send it to Jez, along with £160.00, and he will fettle it beyond recognition and send it back to you. Vastly improved. I strongly suggest you listen to the stock phono stage before sending it to Jez, you will be amazed at the difference between the (albeit very competent) stock unit and the modified one.
It took a few minutes. I wasn’t sure at first, it sounded odd. Very different to my old 640p. I had to adjust to a new experience. David Byrne’s voice sounded odd, there was something.. Timbre! It had more.. lots more definition around the edges. There was clarity at the edge of each sound which was intriguing. It took a moment but I realised what I was getting was “more”. More of everything. The way a cup of coffee snaps everything together, like pulling focus on a camera, all of a sudden I was there. And a liked it a lot. Gil Scott Heron has a slightly croaky voice. I’d never been much aware of it before. I suppose if someone had suggested it to me I might have agreed. But with the Arkless in place there was no question. Every beat of a drum, every fret move, every cough in the studio.. wallop. Details were flying at me and it was grin inducing.
Timbre is a hard thing to quantify in words. But the way the timbre of voices and instruments were portrayed was quite exceptional. Somehow this phono stage digs into the music and pulls more out. You get silky clean sounds, with detail. Listening to Orbital’s latest album Wonky was just huge fun. And that should be what this hobby is about. Finding kit that helps you enjoy your favourite music more.
This humble looking bit of kit has had me losing sleep. I’ve been up late listening three days in a row now!
The unit can be supplied as an MM or MC amp and if you let Jez know which cartridge you are using he will even fine tune the amp to suit!
For those that want to know more technically, please read on. If not, rest assured this is a truly great phono stage, as good as any I’ve heard. The law of diminishing returns is real and if ever a low cost bit of kit highlighted that, this is it!
Technical blurb from Jez:
Both the 640P and 651P are suitable as “donor units” and are identical in terms of circuitry. Any reference to the 640P can therefore be taken as applying equally to the 651P. The newer 651P merely has an on/off switch added and a re-styled case. The Arkless Electronics 640P re-uses the internal and external (wall wart) power supplies, sockets, casework and PCB of the original but the actual circuitry of the phono stage is replaced with an Arkless Electronics design.
•The MC input is now used for both MC and MM cartridges. The standard input capacitors of 220pF are a bit excessive for some MM cartridges and are replaced with 100pF
•The redundant MM input sockets are now utilised for cartridge loading by the use of loading plugs. By this means the inputs can be loaded with any desired combination of resistance and capacitance to suit any model of cartridge whether MM or MC. As standard, a set of loading plugs offering 100 Ohms in parallel with 1nF are supplied and will be a good match for the majority of MC cartridges. Without the plugs the cartridge sees 47K and 100pF which will suit most MM cartridges.
•Customers can of course specify any loading, and if familiar with the art of soldering can change the plugs to their own requirements. Extra loading plugs to any customer specified value can be supplied (at extra cost) at any time.
•The original input stage is disconnected and is replaced in its entirety with an Arkless Electronics designed low noise stage which allows direct coupling of the cartridge to the first stage, thereby removing all capacitors from this delicate part of the signal path.
•Gain is set for either MC or MM cartridges by removing the lid and cutting one wire loop per channel. Simply solder the ends of the loop together again to go back to MC….. Customers can of course specify whether the amp is to be set to MC or MM as supplied. Those who would rather not dabble with even this limited amount of soldering can return the unit to have it carried out here but a small fee will be chargeable.
•Output is much higher than before. Output level could be a bit marginal with low output cartridges in original 640P.
•The stock MM stage is completely disconnected.
•The original MC/MM switch is removed and bypassed.
•The output of the first stage is direct coupled to the RIAA equalisation stage, removing yet another electrolytic capacitor from the signal path. The RIAA stage itself has been completely recalculated to give tighter accuracy to the RIAA standard and to work at impedance levels more conducive to good sound. The capacitors used in the RIAA network are a critical aspect of the design of any phono stage and Arkless Electronics have had close tolerance, low loss, polystyrene capacitors made to order for this application.
•The original NE5532 op-amps in the RIAA stage are replaced with much better quality item.
•The grounding regime of the amp is changed to improve sound quality.
•The original subsonic/warp filter circuitry is disabled and the switch removed. The output relay (for switch on delay to avoid thumps etc) is also bypassed. These can both be left functioning if a customer requests it but it is recommended that they are removed on sound quality grounds.
Further upgrades can be carried out for any customer who has already purchased the Arkless 640P and who wants to take things further. The laws of diminishing returns very much apply here though!
Discuss the Review Here.