A DIY Beauty: Pete Millett's Butte Headphone Amp
Ok, ok, so it's not a whole lot to look at but that's one of the things that makes me like it. And I really like it a lot.
Disclaimer: I'm a long time admirer and occasional collaborator with Pete Millett. I will build just about anything that he designs because I've never been disappointed with the end product. That said if he laid an egg I certainly wouldn't give him a pass just because he's a nice guy. If anything it raises the bar and makes me expect more from him.
The Butte (pronounced "byoot") was originally released in 2011 as a commercial product from Apex Audio. Apex, for those that don't know, is the dynamic duo of Pete and Todd Green; their products are sold at Todd the Vinyl Junkie. This combination has produced some truly epic results including the spectacularly sounding and priced, Pinnacle. The Butte was decidedly on the other end of the spectrum and having finished its commercial run, is now available as a DIY project with essentially the same circuit converted to thru-hole components for ease of assembly and with a few alternate parts to lower the build cost.
PCB's are able to be ordered from Pete's ebay store and you can buy the professional-grade chassis that I used there as well. You are of course free to case it up in whatever you choose, one of the great joys (and pains) of DIY. Parts are readily available from the common vendors (DigiKey, Mouser, etc.) and here's where we get to one of the best parts about the DIY Butte. It's cheap. Mind-boggling cheap. All in, with the enclosure, board, parts and some shipping you're out less than $200.
And Pete has gone to great lengths to make the whole process painless. He's put together a very detailed build guide, sells the hard to get bits (PCB and chassis) and even has a one-click shopping cart at Mouser to buy the remainder of the parts. Pretty awesome if you ask me.
So how was it to build? Refreshingly easy. The last thing that I built was a highly complicated tube-based amplifier complete with a power supply that can kill you and many, many nights of point to point wiring permutations. So when I got to sit down with a small box of parts, a single PCB and have it all up and running in less than 2hrs it was very satisfying. As mentioned above Pete has put together a detailed and comprehensive build manual and as such even the newbiest-newb should have no issue with building one of these. The only true challenge is if you elect to install the two surface-mount parts that offer a slight reduction in overall distortion. Having built many surface-mount projects this wasn't an issue for me but if you haven't done much (or any) of that, I'd steer clear. The difference, per Pete, is debatably audible.
Once past that stage is all pretty much plug and play and if you order using Pete's link with Mouser your parts bags will even come labeled to match the PCB. It's little things like this that make it such an approachable project. Assuming that, like me, you know and understand just how hard it is to hand craft a professional looking chassis, and you select the one from Pete's Ebay store there isn't much left to say about the build. Slide the board into the chassis, install the Panels as directed by the manual (there is a little subtlety involved) and you're done.
Well then, how was the amp to live with day to day? To my ears the answer is pretty darn outstanding. The numbers back that up, so let's start with a of few of those from the commercial product page.
Max output leven into 150 ohms @ 1kHz: 7.2V RMS / 20V P-P / 340mW
Max output level into 33 ohms @ 1kHz: 5.0V RMS / 14V P-P / 750mW
Peak output current: 200mA
Output impedance: 3 ohms
THD+N 1V 1kHz 150 ohms: 0.003%
THD+N 1V 1kHz 33 ohms: 0.005%
FR: 20-20kHz +/- 0.1dB
FR: -3dB DC - 240kHz
Noise 400Hz - 30kHz: 30uV
Max gain 1kHz: 20dB
Dimensions: 4.3" W x 5.3" D x 2" H
One important thing to note from those specs, this amp has a lot of gain, which is to say, it goes all the way to 11. This has its good and bad points. On the one hand, if you're feeding it with a low ouput source or driving hungry headphones you'll appreciate the beef. On the other hand, if you're using a higher output source and/or easy to drive headphones you may be left with a somewhat limited range of volume adjustment. I tried the amp with everything from HD800s, LCD-2s, Grado SR-100s and even a few sets of CIEMs and I was always able to find a way to use the amp comfortably. The CIEMs presented the biggest challenge and revealed that the amp does have a slight amount of hiss. It wasn't anything that was objectionable while listening to music, but it is there. Hey, that's why you have more than one amp, right?
And this is a desktop amp, not a portable, so for most this will really be a non-issue. That's where the really good news starts to hit. Yes, it's a tidy utilitarian package if you elect to use the stock chassis, but if you want fancy all you have to do is design your own. Make no mistake the amp has some great features too, my personal favorite being a front panel switch to change between the two rear panel inputs. Oh, and those two inputs are a combination of one set of RCAs and an 1/8" jack. So whether you've got an iPod, CD player, or both, you're covered. Why many manufacturers still make desktop products with only one input boggles my mind. My next favoritea front panel power switch. Hallelujah!
But let's get back to how it actually performs and sounds. The Butte is a wonderfully neutral amplifier, having natural but impactful bass and an extended but not harsh top end. Really, I found nothing to nit-pick about even if I ignored the bargain basement build price. My favorite combo, and one that I spent hours listening to, was feeding the Butte quality source material and driving the HD800s. Generally speaking I've not really found the HD800s to be all that enjoyable off of low output impedance amplifiers but for whatever reason they seemed to click with the Butte. There was plenty of fatigue-free detail and nice amounts of slam from the low end. I never once found myself wishing that I'd hooked up something else.
Bottom linePark this little guy next to products costing several multiples of its build price and I doubt it'll do anything but than impress. Sure, some of the higher-end amplifiers that I own are capable of rendering more detail but you'd be adding another zero to the cost of the Butte to get there. So, if you're thinking about dipping your toes into the pool of DIY headphone amps I don't think there's a stronger recommendation that I can give for where to start. Skip the typical, throw-away type projects and invest a little bit more into something that is likely to be infinitely more useful and enjoyable. Highly recommended!