Paul Hynes Power Supply for Logitech Touch

[MartinT]

As an alternative to buying a ready-made power supply for my Touch, I built one using Paul's latest PR3i-5 module, set for +5V. This is a rework of the highly successful PR3 as used in my Bushmaster power supply (in that case, a PR3-16).

It's very easy to build a project based on the PR3i when ordered in 'energy storage' version, where rectification and reservoir capacitors are all on-board. All that is required is a 6-0-6 50VA transformer (I used a Multicomp from CPC), a project case and some connectors, wiring, terminal block etc.

There's no need to go into a detailed build sequence as it's pretty straightforward. I used Paul Hynes Clearsilver XL cable as the mains feed into the PSU - captive this time as I find cutting holes for IEC sockets painful.

The case is the heatsink since the module barely gets luke-warm when powering the Touch, with a little heatsink compound to aid heat transfer. I left the unit on soak test for a while and adjusted the output for a perfect +5V output.

Showing 'fitting up' the main components into the case before drilling. I used the same Maplin case as for the Bushmaster PSU. Some medium size sorbothane feet help isolate the PSU from vibrations.



The finished Touch PSU (right) got a green LED to differentiate it from the Bushmaster PSU (left).



The Paul Hynes PSU helps elevate the Touch to a serious high end streamer, especially with the EDO applet installed to enhance digital output to the Bushmaster. The sound is highly detailed with absolutely no harshness and a low noise floor. I have a test track recorded at -70dB and that is a stiff test of DAC linearity and noise floor. It was still recognisable as music when the volume was turned up way high, a very good test of low level detail resolution.

Hi-res files sound extremely fine, again with that combination of fine detail and non-harshness. The ultimate limit to sound quality now appears to be the Bushmaster itself, no bad thing since it's a very fine DAC. The point being that the Paul Hynes PSU with Logitech Touch form a low cost file streamer of great value for the DIYer.

[Reid Malenfant]

Indeed, I have a PH PR3i-5 set at 5V powering my HDMI distribution amplifier, the difference it made over a regulated linear (non SMPS) wallwart was not to be sniffed at

Just waiting for another PH marvel to arrive & they'll both be going into a custom box, one for the HDMI distribution amp, the other new one to power my DVDO iScan video processor. At the present it uses a 6V 6Amp SMPS...

I can't imagine the difference it'll make


Nice one Martin

[MartinT]

At the present it uses a 6V 6Amp SMPS...

I can't imagine the difference it'll make

Agreed - you'll need a goodly transformer that won't buzz and a decent heatsink for that.

[Reid Malenfant]

Agreed - you'll need a goodly transformer that won't buzz and a decent heatsink for that.

Having discussed things with Paul, & compromised a tad Extra storage capacitance, like over 47,000uf worth if not more...

I have a 12 0 12V 300VA toroidal transformer that has mysteriously been turned into a 6 0 6V transformer through some clever cutting of the windings

That is effectively a 6V - 50A transformer given the setup. Allowing for voltage drop over the regulating Mosfet I should still be able to draw 40A or so, miles more than the iScan will ever require.

It appears to draw a fairly constant current of a fair bit, the thing produces as much heat as an integrated amp run at decent volume

I have a nice heatsink that is at least the same size as the one used on the PR7EHD, with a lower input to output voltage difference it'll do the job more than admirably.

[morris_minor]

Being a DIY numpty, I bought one of Paul's SR3-05 supplies for my Touch and haven't looked back. With a downstream chain of an Audio-gd Digital Interface re-clocker and a Metrum Octave NOS DAC, digital has never sounded better - and the Touch (with TT3 and EDO) now definitely surpasses my Transporter in the musical-involvement stakes.

For what some folk dismiss as a "gadget", the Touch sure sounds good

[Marco]

Paul is undoubtedly and expert on power supply design, as he's studied it in depth more than most, but any properly designed linear power supply will improve a half-decent music streamer, simply because the cheapo on-board SMPS units seriously hobble their potential sonic capability!

Marco.

[realysm42]

Chaps, as I use a PC to stream my music to my Dac (it's my only source) would having a high quality power supply be of benefit? I'm guessing yes because it's basically what you've done here right?

I don't understand how upgrading the power to something that streams a digital signal couls have an effect on the SQ; I get it with things like amps and dacs though.

Care to educate me?

[MartinT]

Noise, jitter, interference can all pollute the digital stream and give the DAC a harder time decoding it, with consequent deleterious effects on the sound.

[sq225917]

Have you just replaced the wallwart with this, or does it run direct to some part of the pcb replacing one of the pcb mounted switching regulators?

[realysm42]

Noise, jitter, interference can all pollute the digital stream and give the DAC a harder time decoding it, with consequent deleterious effects on the sound.

Interesting, thanks Martin. Ties in with what Gazjam said.

It's funny that on certain HTPC sites they sell psus with no mention of the effect it can have on sq; I'll bare this in mind when picking.