prototypes

X-1

An early prototype which was built without any testing. Components: raspberry B w/ hifiberry DAC, EDIMAX EW-7811UN, 500 gb usb hd, 4x diyinhk TPS7A4700, 80VA Sedlbauer toroid.

It's sound was convincing enough (easy match for a Naim CD5i) to form a team. It's been permanently used since 6/2014. 

X-2 testing ground

Here we tested different smoothing caps (also an array), a couple of cheap regulators, a first SuperTeddyReg and various DACs.

X-3

This prototype was meant to be put into a Naim shoebox. It never made it there due to a few short circuits. We kept focusing on the star ground issue (nicely shown between the caps) but switched later to a center tap ground @ the PSU instead of using the windings of the toroid separately.

Components: raspberry B+ w/ our favorit IQaudIO Pi-DAC+ (made in Scotland!), 4x dual stage regulators w/LT1086CTs, Kendeil caps, Talema toroid.

X-4 testing ground

Now we wanted to know more about regulators. This setting allowed side to side comparison of various home made regulators for all four stages (cpu, usb, digital & analog DAC). Top left counterclockwise: dual stage LT1086CT, dual stage LM317, single stage LM317, dual stage LM317 w/ LEDs reference, 4 SuperTeddyRegs.

X-5, the spaghetti monster

In this prototype we combined a custom built transformer w/ 4 specific windings with 4 Schottkys, 4 caps, 3 single stage LM317 and one SuperTeddyReg on a copper plate (ultimate star ground & thermal mass).

X-5 testing grounds

What a mess. Various approaches to transformers, caps, regulators,....

X-6 series [chrome bumper shoe box DAC] mark I

This player fits nicely to Naim Audio's chrome bumper series. The front switch can turn of the internal hard disk when using an usb stick and can reboot the raspberry. Inside we a raspberry B+ w/ IQaudIO Pi-DAC+, 4x acoustica'ised tracking preregulators w/LM317 + one SuperTeddyReg, one Kendeil cap w/ a center tapped 80VA toroid.

On the second picture one can see the +5V and +3V3 supply to the DAC and +5V & ground to the pi. The vertical regulator is the SuperTeddyReg and the row behind are the four tracking pregegulators. The switch is there to turn off the hd in case of the use of an external usb flash drive and to reboot the pi.

X-6 series mark II

This player is the next stage to fit Naim Audio's chrome bumper series.

Center tapped 80VA 2x 9V Talema transformer, 2x Kendeil 10000uF/63V caps in a CRC filter configuration, 4x dual stage LT1086CT reg,(cpu, dac digit, usb, hd), 1x 3V3 SuperTeddyReg, IQaudIO Pi-DAC+ (modified for direct 3V3 supply to analog stage eliminating the on board LDO), Raspberry Pi Mod B+, internal HD, wifi + LAN + 2x USB.

Part List

Very good!

We start to enjoy once more music we don't want to listen to anymore (the few tunes we always use for comparison like Vivaldi: The Four Seasons/Winter/1. Allegro Non Molto by Alan Loveday/Neville Marriner which can be a little bit stressful) and voices are more natural (i.e. Sad Old Red/Simply Red; Tudo/Bebel Gilberto).

The output level turned out to be a little bit higher due to the direct 3V3 power supply to the analog stage. Everything else is less of anything that's not music (we assume thanks to PFM and the CRC discussion @ PFM).

X-7 series [the cu.DAC] mark I

This player is the next stage of the star ground copper plate approach including a top and bottom aluminium casing plate. This is our "form follows function follows finance..." design statement.

Noratel 80VA 2x 9V transformer, Kendeil 10000uF/40V (ebay), 6A Schottky diode, 3x single LM317 reg, 1x 5V SuperTeddyReg, IQaudIO Pi-DAC+, Raspberry Pi Mod B+.

Here are some pictures of the assembly process. A manual would be nice if we would just have time for that. 

X-7 series mark II

As above + adding a CRC filter configuration

X-7 series mark III

As above + adding a filter (single reg w/ VBE)to the 3V3 LM317 for the DACs digital section. We did also move the mains plug to the other side so that mains + RCA audio out are on the same side.

X-7 series mark IV

As above but with Hifiberry's DAC+ PRO. Pushing it a little bit further we cut the onboard LDO (5V to 3V3 for AVDD) to supply AVDD with Teddy Pardo's finest 3V3 regulator and

add a separate 3V3 supply for the onboard dual domain master clocks.

X-8 series mark I

For budget projects we like the idea to install a mdXS inside a good old amplifier. 

Here's one project with a NAD 3020i (Vishay 50V/6800 re-cap + taking the phono preamp off the power rail) - with a pair of Mission 760i it's a great set for a small budget. 

3D printed PSU with Talema 30VA 2x 9V transformer, 2x CRC 6800uF/35V, 6A Schottky diode; 2x single LM317 reg(cpu & usb), 1x single reg + Booster(DVDD),  1x dual stage LT1086CT reg (AVDD), Hifiberry DAC+, Raspberry Pi Mod B+.

Coming up...

X-9 series [cu.dips.DAC]