WHAMMY Headphone Amplifier
Description
The WHAMMY Class-A headphone amplifier
Wayne Colburn, the genius at Pass Labs who for the last 25 years has designed essentially all the things that aren't speaker amplifiers, wanted to make a fun, high-performance, fantastic-sounding, Class-A, DIY headphone amp for this community. We call it:
Wayne's Headphone Amp Must Make Yourself
Yes, it's a silly name. But it's cute. And it explains a lot about it. So it stuck.
Given the explosion in the popularity of headphones, as well as the unbelievable amount of choice and variety in the market, it seemed that a simple and great-sounding headphone amp would be a great addition to the DIY community.
Because there are so many choices of headphones, from Planars to IEM's, high impedance or low, this amp will drive any headphone you want to throw at it (Well, not electrostatic headphones directly, no amp like this will, but it will happily drive a step-up transformer like Stax).
Wayne wanted a universal headphone amp for his desk. This is the fruit of that idea. It’s made to be made in an afternoon or an evening and it has no builder adjustments, so it’s going to have a high likelihood of success and completion for beginners and experienced DIYers. 
It's an all in one PCB, just wire the AC & fuse, input and output jacks. Add a selector switch if you like.
Class-A output stage with enough current to drive anything. It also makes a wonderful line stage with about 14db of gain.
Your choice - PCB or PCB plus parts kit
We are now selling both the a WHAMMY PCB by itself, as well as a parts kit that includes the PCB, and everything else you need to build the WHAMMY other than a chassis.
- We are working on a chassis for the future and will definitely release one, but we aren't going to rush it
- 6L6 has done a great WHAMMY build guide and the supplied parts will match the build guide, more or less
- We have now seen multiple successful builds of this new kit, and are now opening pre-orders for the kit, shipping January 11th 2019
PCB Details
- 218mm x 160mm (8 5/8" x 6 5/16")
- Black with gold immersion traces
- 70oz Copper
Kit Details
The kit includes everything to make the amp except the PCB and chassis. All components are of the highest quality.
- Dale RN55 milspec resistors
- Panasonic FC & FR series capacitors
- Elna SILMIC II capacitors
- Solid aluminum anodized volume knob
- Alps "Blue Velvet" potentiometer
- Neutrik RCA connectors
- Schurter filtered power entry module with spare fuse
- TRS Headphone Jack
- IRF610/9610 Power MOSFETs
- Texas Instruments RC4580 op amp
- Teflon insulated silver plated copper milspec wire for I/O connections
- Silver bearing eutectic Kester 44 solder for I/O connections
- All nuts, bolts and standoffs to attach external connectors and the PCB to a chassis
Illustrated build guide
Most of the info you need to complete this project can be found in the first 6 posts this thread, a well-illustrated guide showing how everything goes together.
- Step by step WHAMMY build guide on guides.diyaudio.com
- WHAMMY build guide and general discussion thread
- Rough Bill of Materials (this is not the BOM used for the kit)
Video
Here's a video of Wayne talking about the Whammy at Burning Amplifier Festival 2017 -- Wayne Colburn at BAF '17
I have several other DIY headphone amps. This one has the most well behaved turn on and turn off transients, i.e. almost none. No worries about damaging delicate drivers. Whammy has absolutely gobs of gain without noise. It can easily drive even low sensitivity planar magnetic headphones. I'm on #2 of 5 different front end opamps that I bought to try out and the differences between #1 and #2, although subtle, are there for the listening due this very clean circuit design. DIY audio doesn't get any better than this.
Build includes switching HP jack, preamp output jacks, noise filtering IEC inlet, front panel power switch and LED. All easy to add, although the Hammond chassis does get a bit tight and parts layout a bit critical.
I have 4 other DIY headphone amps and this one is the quietest and has the most well behaved power turn on and turn off characteristics. I surmise that's due to its excellent internal power supply. The circuit has gobs of gain, enough to drive even my low sensitivity planar magnetic headphones. I added a 2 amp noise filtered IEC inlet, power switch/LED and output jacks to the original design. This unit functions well as a preamp, quite beyond my expectations. The new heart of my desktop system.
Building the Whammy kit was straightforward with only one operator error around the three regulator strategies..if the preferred one is LED regulation, that should ideally be the first one outlined in the Guide. Its a small point and Jim ( 6L6 ) was kind enough to message and Facetime so we sorted it out very quickly. He also suggested a simple to wire the kit for a pre-amp output using a switched phone socket and how to get a Blue LED power on connection from the board. Very helpful
I built the board into a Modushop Galaxy 1 U 230 x 230 / steel cover / 10mm faceplate enclosure ( see pix ) That gave plenty of space for the mains connector and space to fit a bigger phone connector. Ideally the faceplate would be machined to fit the pot and socket which are both designed for thinner faceplates. I made a little sub panel to carry both items and the power on LED., as well as lining up all three items on the centerline of the fascia ( a bit obsessional I know ) This was acheived by using a 3mm spacer strip between both the top and bottom panels and the case sides. Combined with the thinner steel covers that gave just enough clearance for the board and components. If the covers were made with the slots above the regulator heat sinks cooling would be improved but I havent noticed any problems. Jim was a bit concerned about the screening afforded by a case with no continuity of grounding between the panels but any noise is below my tinnitus level so I dont perceive a problem! The use of the Galaxy case gives a good visual continuity between Whammy and my integrated ACA and Monoblocks...all it really needs is the cool Pass logo from the ACA.
My son and me build each an Whammy. Easy building, excellent sound. No trouble building them. After recieving the parts we spend xmas time together stuffing the beautyfull pcb. A instant-sound-project :)
What a great little board. Easy and fun to build, parts readily available, and sounds phenomenal!
Very good and very easy built project .
Excellent performance.
The board quality is beautiful and easy to build. Sounds absolutely fantastic, it's my everyday headphone amp, super happy with it. I chose to use a Burr-Brown OPA2134PA Op-Amp and Fairchild finals.
This sweetly doubles up as a preamp for few main amps...tonal quality is amazing...must have build for newcomers for sure
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