PASS DIY Headphone Amp - WHAMMY
Apr 17, 2018 at 3:28 PM Thread Starter Post #1 of 274

HiGHFLYiN9

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Wayne Colburn of PASS Labs was kind enough to release a new DIY headphone amp circuit into the wild, the WHAMMY, standing for Wayne' Headphone Amplifier Must Make Yourself. It's a nice simple build, no need to match parts or make adjustments, so it's perfect for the budding DIY builder. It's also inexpensive. The PCB, parts and chassis should be under $200 without much effort. Jim Tiemann aka 6L6 of DIYAudio has been kind enough to coordinate the project and has been instrumental in making it accessible.

You can read more about the project here: http://www.diyaudio.com/forums/pass-labs/317803-whammy-pass-diy-headphone-amp-guide.html

Boards can be procured here: https://diyaudiostore.com/collections/printed-circuit-boards/products/whammy

And you can learn more about the circuit design here:


I'll be building one myself and hope some of the members here will as well.


WHAMMY Headphone Amp 2.jpg

WHAMMY Headphone Amp.jpeg
 
Apr 25, 2018 at 10:47 AM Post #8 of 274
Getting close Jamie, just have to drill some more holes in the chassis and get everything mounted up. Yes, the resistors are Kiwames (2W Koa Speers from Mouser). I have quite a stash of them so I use them for everything. The silver caps are some old Sprague PIOs I had in my parts bin. Since those caps are directly in the signal path on the input I wanted to use some good quality ones.
 
Apr 28, 2018 at 5:54 PM Post #11 of 274
Thanks Jamie! I didn't put as much thought into this one as I typically do, but it was a fun, enjoyable build.

Have a few more pics below. Chassis is from IAG DIY Tube Audio Products. He lists his chassis on ebay and on his website. Hand-made in the USA. (No affiliation).

The front panel has a four pin as most of my headphones are wired that way, so it saves me from using an adapter.

Wiring is scraps of Cardas I had in my wire bin, 4x24, 2x24 and 2x21 and some 24AWG. Pot is Audionote. IEC filter is Furutech, picked a few up when they were discontinued for a nice price. RCAs are Cardas. Most of the caps in the audio section are SILMIC II. I know Wayne mentioned in the video they aren't as reliable lately, but they sound good... so hopefully they'll be okay for a while. Resistors are mostly Koa Speers 2W with some Vishays here and there. Input coupling are vintage 100V Sprague PIOs. PSU caps are Nichicon "For Audio"... for whatever that's good for
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Everything else is from the BOM. If you use the same parts you should end up with a warmer sounding amp... although the op-amp will probably make more difference than all those other items.

WHAMMY bottom DIY headphone amp.jpg WHAMMY DIY front headphone amp.jpg WHAMMY DIY rear headphone amp.jpg WHAMMY internal front headphone amp.jpg WHAMMY internal rear headphone amp.jpg
 
Apr 30, 2018 at 6:38 AM Post #12 of 274
Very interesting project. I am a big fan of Nelson Pass and have owned two FW amps.

I would be interested in any listening impressions and also to know if there are any importable BOMs for Mouser and Digikey. I found the BOM on DIYAudio a bit hard to follow.

Thanks!
 
Apr 30, 2018 at 8:24 AM Post #13 of 274
whammy.jpg whammy 2.jpg Whammy 3.jpg Here is one I just completed using the Hammond case, it does fit snugly in there and I had to modify a few things to get the layout the way I wanted. I used a combo switch, fuse, and ac outlet to save a bit of time and I would have mounted it inside except for space and other issues.

I only have about an hour on it so far so it is hard to make in depth statements about the sound but I will say I like the amount of power, the clarity and the total absence of any background noise. I have hooked it to a couple tube preamps just to inject a bit of tube sound and the amp certainly holds its own.

I learned about the build from Highflyin9 and he is a gentleman whose opinions I value and after watching the video, I knew this should be a quality amp.

I got interrupted or my build time would have been roughly six hours, I wanted to use dual Alps single gang pots but the cabinet size would not allow for that. I may build another down the road and steal, um borrow Highflyin's info on the other cabinet.:beyersmile:
 
Apr 30, 2018 at 8:55 AM Post #14 of 274
Very clean build. Looking forward to more listening impressions as it burns in.

Were any of the parts hard to find or just easily obtained from Digikey and Mouser?
 
Apr 30, 2018 at 9:50 AM Post #15 of 274
The parts were not hard to find, I ordered a few caps from Digikey and Mouser but most of the resistors I owned as 2% parts. A couple I had to use in parallel to achieve 499 ohm etc. I have several very accurate meters so on some I just tried combinations till I got the exact results I wanted. The Hammond case is quite snug but I wanted the ruggedness over beauty since I may use the amp outdoors some.
 

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