Bottlehead Crack Headphone Amp just completed, with Speedball upgrade. This amp was purpose built for sale and is NEW condition, professionally assembled. Kit price is $414 as purchased from Bottlehead. .
Soldered throughout with Cardas Quad Eutectic making a nice, virtually spatter-free job. You get a beautiful, clean build with no cold joints/opens, no solder blobs, no singed wires shorting out. I use a temperature controlled soldering station alternating between three different tips to best control solder application to size of terminals and component. The transformer bell was sanded and polished by hand, then clear-coated to prevent rust/discoloration; it looks quite nice and fits right in between the bright, brushed aluminum top plate and the black color of the transformer, volume knob, and jack. All edges on the alder wood base have been very slightly rounded by hand sanding to soften it visually, then all surfaces sanded with 220 grit; it is ready for finish to match your decor by you or a local craftsman. I have taped the Bottlehead badge to the front in a couple photos for viewing, but will leave it unattached in case you wish to finish the wood.
Sound: The Speedball upgrade does better the amp with a blacker, quieter background, and is worth the cost. The amp, thanks to the OTL design, is quick, and immediate; a front-row presentation. Sweet treble, beautiful midrange, and the bass response will knock you out..no kidding. As one buyer, owning a $4K amp prior, remarked - "Amazing that this amp and the 650s sounds as satisfying as some of the most expensive stuff I have purchased, amazing indeed." Don't be put off by "kit"; these are seriously good amplifiers that would have to retail for twice the price.
Finally, the amp has been burned in 100 hours with phones & music, and voltages given a final check, Packaging is thorough double-boxing to assure safe arrival. Tubes are packed in bubble wrap with cardboard wrap, with power cord, Bottlehead badge, and my notes regarding various power/input tube combinations I’ve tried in the amp, as well as a brief primer in case you are new to tube amplification. I'll also include a NOS RCA 6AS7G which is a nice change-up from the GE 6080. Note: if you're not a fan of 12AU7s, the Speedball upgrade allows rolling the 6CG7 or 12BH7 without large voltage mismatch . I like the amp using a 6SN7 via an adapter, as well.
This is an amp designed for higher impedance headphones; I use Sennheiser HD-600s to proof the amp. For more info, see: http://bottlehead.com/crack-otl-headphone-amplifier-kit-specs/
Thanks for looking!
Tubes by Tom