From Hificritic
Audionote CD/DAC 5/6 notes by designer Andy Grove
(came too late for consideration in the review description )
5th Element..well...
Briefly the concept arose from me thinking about the SPDIF interface. I’d been researching and thinking about ways to improve it, and came to the conclusion that the best way to treat it was to think of it as an analogue transmission line.
If you start with the idea that a separate DAC and transport are superior to an integrated player, then you need a way to connect them together.
Now, transmission lines generally require a defined impedance at each end, at the transmit and receive ends and, really, a digital gate doesn’t provide this so I had to come up with a way to buffer the digital internals of the DAC (and the CD player) to provide a nice analogue impedance for the transmission line.
To do that I first of all started to think about a solid state solution, but then I thought I may as well just go all the way and do it with valves, my preferred devices. Starting there I designed both a simple transformer coupled stage with a EF800 pentode, and also a small data transformer one at the transmit end and one at the receive end.
And these are wideband SE, Class A, transformer coupled stages.
I built the prototype for just one end (I can’t remember which, transmit or receive) and gave it a listen. The result was subtle in some ways, yet obvious in others, colours were improved and the HF became more silky and less digital sounding. With this in mind I built a complete system, transmit and receive, and tried that, and the results were even better.
So, it was now obvious that you needed it at both ends of the cable to get the full benefit.
I did these experiments with one of our lower end DACs, but I discussed with Peter and Andy W and we decided that we should make a kind of super DAC 5, using the PSU from the M9 preamp to power the analogue stages. This DAC would have the receiving buffer while the forthcoming CDT-6 would have the transmitting buffer. I also designed a new I/V transformer, using the massive custom Permalloy core which we were currently using in the AN-S9 moving coil step up.
It all came together, and the first proper DAC arrived here, all built with the new parts and technologies. I checked it over, adjusted it and put it in the listening area. Andy Whittle ( sales) and Peter sat down to check it out.
I went back to my lab for a bit and went back down again after the unit had run for 20 minutes, only to walk through the door and see Peter and Andy with their mouths and eyes wide open!
Result!
The name came about because we wanted it to show it’s relationship to the DAC5, but we wanted to show it was separate too. I was talking with Peter Q and said “well, Quintessence is the 5th Element” and Peter said “that’s it, we’ll call it The Fifth Element” and oddly enough, a couple of days later we saw a scientific journal headline about fundamental forces and came up with the idea of the PSU being called The Fifth Force.
