I'd recently found out about a new type of battery designed for electric vehicles - a LiFePO4 battery (that's lithium ferrophosphate for chemistry buffs). Its specifications impressed me (particularly its low impedance - lower than most capacitors) and it's 3.3V output was perfect for powering digital circuits. I bought some. Looking at the Hiface circuit I realised I could isolate the power to the clocks and run them from this battery.
Here's what I said about the sound at the time:
- removed the clock PS series inductor & fed a clean 3.3V from LiFePO4 battery - noticeable improvement in sound - much better resolution of instrument timbre & subtle sounds such as the snare drum & cymbal brushing on Herbie Hancock's The River (my test record) - Corrine Bailey Rae now sounds quite good singing the River or maybe I just got into it after listening to the album for so long. This really is a big step up in SQ - not surprising that a cleaner PS feed to the clocks will improve matters.
After some more mods I said this:
This is the best audio I've had in my system to date - I reckon it would compete well against the best.
The scope confirmed what my ears were hearing with a nice flat line - no spikes!. I shared all my findings (particularly the sound quality differences on my favourite Herbie Hancock track from the Joni Letters) in the public domain on a DIY audio forum. Some people tried the modifications themselves and found similar things. Enough people contacted who were Hiface customers asking me do this micro-surgery on the SMD components on their Hiface board that I started to do it as a service. Eventually it evolved into a more user-friendly boxed component - the MK1 Hiface.