I initially bought a used Whammy from eBay that a seller had built using odd spare parts. It didn't sound terrible but not what I was expecting. So I set about modifying it. It soon became clear that I wanted to change everything so I bought a new PCB and started from scratch, re-using just the case and the heatsinks.
The parts I used that are non-standard are Sparkos discrete voltage regulators, PRP PR9372 non-magnetic 1% resisters, Nichicon FW power supply capacitors and Audio Note Kaisei capacitors and Audio Note silver plated RCA connectors. A Saligny Universal discrete synchronous rectifier instead of diodes from https://evotronix.eu/product/saligny-universal/ Transformer from Digikey and other components from Farnell. I tried various op amps from Digikey and Farnell.
Screened input cable is BICC silver, single core screened, in pink because I bought it on World Trans visibility day and my cousin is a Trans woman, the output cable is DueLund copper in cotton and oil insulation - because why not ? DIY Audio is about making interesting decisions and trying something new like oderous cable and the Salingy rectifier :)
I tried various op amps from the venerable 5532, OPA2134, OPA2132... 134, 1611 LF353... lots of OPA op amps and also a Muses02. The best reasonably priced chip was the OPA2134 which did everything really well, but it was beaten quite clearly by the Burson V7 vivid which is what's in it now. It does run warm so I added some ventilation to the case but even without that I think it would be fine.
The built process was very easy once all the parts had arrived. Planning the build is important as putting large items in first makes adding resistors and smaller parts more difficult later on. There's plenty of space for most things if you use the recommended values, but if you want to increase or change to different types or values, double check the space available. Make sure you can clean the board using a proper solvent mix, especially around the op amp.
The community on DIYAudio is fantastic with a number of people offering great help and support. I'm a latecomer to the project so there are already lots of questions answered which make for interesting reading.
How does it sound ? It's brilliant ! It copes with my 300 ohm Sennheisers very easily, the bass is deep and strong without being overpowering. (Fit the MUSES02 op amp if you want emphasised bass response) It's easily the equal of most commercial headphone amplifiers.
The PCB quality is very good, double sided and if you find you need to de-solder a part, the pad doesn't automatically lift, as happens with even good commercial products. Being black it looks great with contrasting components, hence the red resistors.
I'd really recommend this project to anybody, forget the fact it's relatively easy to build, what you end up with is a great headphone amplifier which you can modify and test ideas on for years to come.
Many thanks to Wayne Colburn of Pass Labs for the design, you know a Pass Labs design is going to sound great !
