MY Mid 2023 DIY StereoCoffee/Hypex
Integrated Amplifier
The sheer musical enjoyment of my July 2023 StereoCoffee ‘end game’ kit convinced me to bite the bullet and attempt a serious rebuild in an aluminium enclosure to complete my own ‘end game’ system.
My constant stream of DIY Audio Projects have a low WAF. This build has sorted that but it took me around 5 days to avoid rushing errors, for the first time ever.
After making DIY preamp enclosures from timber or perspex for the last 10 years, I've bitten the bullet and bought a $145 aluminium enclosure kit from Douk on Ebay and it makes me feel much better. Everything even sounds better. No instructions provided or required with this one.
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I assumed the kit would be coming from Asia and take a few weeks. It was bought on Sunday night and was in my hands at 9am on Wednesday.
This enclosure kit weighs about 2kg and is precisely machined from 8mm and 4mm heavy gauge aluminium. Bolts are stainless steel with hex heads and my kit included about 50 extras, for mounting modules, I assume. Panel fit is perfect.
The square power socket hole is pre cut and threaded. It can be rotated for left or right side entry.
LIMITED TOOLS
I have a cheap and slightly underpowered drill press, limited skills, some sharp drills and a few well worn taper bits that were used to drill the 18mm front push button switch socket and 22mm for the Start and Finish balance controls on the side. The taper bit had no trouble with the 4mm side and rear panels.
The hardest job drilling was the 18mm hole through 8mm aluminium using the large taper bit which required trilling from both sides. Water and WD40 sped up the drilling process but also caused jamming when the flutes became clogged with cuttings.
SNAGS
Front Panel Thickness
The supplied selector switch thread is too short for the 8mm front plate and was replaced by one I had on hand. The length was sufficient but it was missing a locknut with an oddball thread. As the hole I drilled was a bit smaller than the thread, I drilled a slightly larger hole from the rear and about 3mm short of going through. As luck would have it, I was able to create a rough thread in the 3mm remaining in the hole. That appears to have locked the switch in thread.
Mounting the Hypex Module to the Base Plate
Note: This Hypex module is an OEM module from an abandoned ESL design experiment I was working on, in conjunction with a panel manufacturer.
The Hypex base plate is designed to be mounted on a heatsink. The thick base plate is ideal for this and the Hypex doesn’t even get warm. However, the 8 holes that mount the base plate are asymmetrical and MUST be drilled EXACTLY. Hypex supply a template that must be printed at exactly 100% and can easily be taped to the panel and punched.
To my horror, a Bunnings, spring loaded centre punch made its dent 1.5mm too high and 1.5mm to the left from the diagram and I thought I was about to fail. Fortunately it repeated this on all 8 holes and ended up a success... and I always thought it was my faulty workmanship.
SOCKETS
After a multitude of past socket mounting disasters, I decided to align them centrally on the horizontal plane. This enabled the rear panel to be flipped, if I miscalculated the component placement on the base plate.
Basically I’m incapable of aligning two holes. This time I used a smarter method, using a timber slide board, mounted on the drill press plate. Only the horizontal spacing had to be measured, halving the error possibilities. Paper was used to protect the panels from scratches.
MOUNTING the new StereoCoffee Components
My previous build was a mess after so many upgrades and I had also miscalculated the width of the new enclosure. This called for a rethink and it seemed convenient to mount the Main Control Board vertically on the left side panel.
It's now much neater and has enabled me to hide most of the wiring along the side which made connection errors easier to find. I can't do much about the Hypex input wires which are connected directly to the StereoCoffee output. Having one less set of interconnects has improved SQ significantly.
The end silver RCA connectors enable the LDR attenuator to output to an external amplifier after unplugging the Hypex input socket, which can be handy for comparisons with the Hypex.
The 12v/12v toroidal transformer is mounted using a plastic sleeve to electrically isolate it’s mounting bolt from the chassis.
I’m really impressed with this aluminium enclosure because of its versatility. The side panels are around 4mm thick and it should be possible to rotate the enclosure 90 degrees if you don’t want to tackle drilling 8mm aluminium. The top and bottom plates are identical so it is also possible to flip the enclosure if you need to swap cable entry from the right side to left.
I guess I have run out of projects now and can enjoy some superb music after I clean up the dining room table.
WHY DOES IT SOUND SO GREAT?
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Hypex Amplifiers are extremely silent and can handle enormous dynamics effortlessly.
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Having two components in the signal line and being passive makes the StereoCoffee an obvious partner.
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The fact that the StereoCoffee does NOT amplify the signal from your source eliminates distortion and harshness at high listening levels while the absolute background silence allows the signal quality to retain its character and purity at low listening levels.
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NOTE: Interconnect choice can noticeably alter sound characteristics too.
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< The front panel is 8mm thick and required drilling for Volume/Selector Switch/On/Off switch.
< The circuit boards were positioned on the base plate to check spacing before drilling.
< The StereoCoffee circuit boards were mounted on perspex using nylon standoffs and Jaycar double sided mounting tape was used to mount them to the bottom and side panels so they can be moved.
< The Remote volume control board was mounted on some thick perspex glued to the front panel with Araldyte.It's now much neater and has enabled me to hide most of the wiring along the side which made connection errors easier to find. I can't do much about the Hypex input wires which are connected directly to the StereoCoffee output. Having one less set of interconnects has improved SQ significantly.
