Bottlehead Crack OTL Headphone Amp -TUBES baby..TUBES!!

I've discovered that it's possible that I have too many headphone amps. So my highly upgraded Crack is up for sale. This will work with high impedance (200 ohms or higher) cans ONLY. This is the version 1 crack and does not have the international transformer - US 115 ish voltages only. It does have the Speedball upgrade installed as well as numerous other upgrades that I will list below.

You can buy this thing in kit form direct from BH, unassembled with the stock Alder base for $430. I'm asking $500 + shipping (from Rockford, IL) and any fees. It will come with tubes, maybe more than 1 each. I need to check stock.

Tubes pictured might not be what it comes with. This is not a stock picture and is the actual unit (all pictures are of the actual unit).


1) Custom Oak Base and includes the BH badge as pictured. This base is extra high to accommodate the modifications made. There is a 1" or so Sharpy mark on the base that I'm not going to try and remove. I can provide a picture if so desired. Finish on the base is Polyurethane.
2) Changes to the power supply:
Instead of a CRCRC filter this is a CRCLC. The last resistor was replaced with an inductor. The resistor that is still in the circuit was upgraded from a sandcast to a non-inductance one. I don't remember the brand...it's "green".
The two first capacitors are RubyCon's and the last is a Nichicon. The last capacitor is also tipped with a ClarityCap film capacitor.

Diodes are Cree Shotkey replacing the IN4001's in the picture above with a board assy.


Wiring is 90% upgraded. Input wiring is Cardas, most of the rest is cloth wrapped solid copper. Input RCA's are the high end Vampire (I believe solid copper with a gold plate, note the dual red/white stripes). Volume knob is from Goldpoint and the stock volume pot replaced with Alps Blue.

Output caps are Audyne film tipped with Sonicap.
The box is tapped for pointy feet but at this time I have rubber's on it. If I can find the pointy feet I'll include them.
The popsicle grid is there to keep the output caps from bouncing around.


For those of you unfamiliar with the BH kits the top plate is NOT secured to the base. If you turn this upside down very bad and evil things will happen and I won't be fixing it for you!! If you reach up under the base with the power cord applied you'll get shocked. So, if you have small curious children either don't buy this or keep it safely higher than they can reach.

I also own the BH Crack-a-Two-a (a fancier version of the Crack), the S.E.X. and the Mainline. The Crack and Crack-a-two-a sound similar but even with the upgrades the Crack IMHO is beaten by both the other dedicated headphone amps. The price point dictates that also.

Tubes are the 12AU7 and 6080 or derivatives thereof. With the speedball installed you can mess around with more 6080 types. DO NOT use anything other than 12AU7's or their direct replacements. Doc (the Bottlehead master) has stated that bad things happen when you do that.

Info from Bottlehead:
https://bottlehead.com/?product=crack-otl-headphone-amplifier-kit

If you're curious about what tubes you can roll there is a 125 page post on specifically that:
https://bottlehead.com/smf/index.php?topic=663.0

If you promise to be careful and not fug this up I'll throw in the 12AU7 to 6SN7 adapter. Once this is in place both the 6080 and 12AU7 sockets are IDENTICAL and if you switch tubes don't call me... No charge for the adapter (I have two).

If you have any questions please ask. I will only charge 2x shipping for local pickup.