Someone was kind enough to provide a link to this amp on ebay in the Matrix M-Stage thread. I thought I would be a great amp around 1/2 the price of the M-Stage and an easy DIY project to pass the time.
EDIT 04/13/2011: You can now buy the Lovely Cube Premium fully assembled.
For details: http://www.alicemagicbox.com/lasercollection/lovelycubepremium.html
The "Lovely Cube" is sold on ebay by Laser Collection. It runs about $100 shipped for a fully populated board, a pair of nice quality RCA jacks, some heat shrink, a few SIP connectors for the inputs, and a couple of LED's.
The vendor also sells the rest of the components you need to complete the amp: 220v transformer and case as well as unpopulated boards.
The Lovely Cube is an exact copy of the Lehmann BCL where the Matrix M-Stage is a slightly altered version. Here's some pictures I borrowed from the ebay auction:
Bottom of the board with the Gain adjustment DIP switches.
Alps volume pot
Swappable opamps. I switched the SOP + adapter for the DIP8 version of the OPA2134 I had laying around.
The amp arrived via normal HK Post about 2 weeks after I ordered it. All components look to be name brand and high quality.
Be aware that it came with no instructions of any sort, so you'll have to be a little familiar with DIY. In the picture above I've labeled all the wiring points for everyone's reference.
On the far left is the primary input, grounds in the center and signals are the outer connectors.
The center 3 connection points output 15V DC. It is used in the USB version of the Lehmann BCL to power the DAC and USB ports. Pretty nice addition since you can use it with a voltage regulator to power a DIY DAC.
Next to that is the 2nd inputs, I believe these are muted if you plug a headphone into the 2nd headphone jack. I did not connect this in my installation.
Lastly the power input with convenient screw terminals. The amp has an internal PSU so all you need to provide is a 15V AC transformer.
Here's a internal picture of a real Lehmann to get an idea of how things look wired up.
Going to reserve this space for further impressions. My current install in a old external CD-Rom chassis powered by the DY-1 power supply that came with the Head Direct EF-5 amp set at 16V AC.
I have a minor grounding issue since my case does not have a faceplate. I hear buzzing on my low Z phones when I touch the volume pot, I think I need to ground it to the case. I'll update this section once I get a new case or get this issue resolved.
Edit 07/07/2010: Buzz is now gone. I had to ground the Alps pot to the star ground in my case. The amp is now totally silent with no music playing and the volume turned all the way up with my 42 Ohm ATH-W1000X's.
I'm not the best amp reviewer here but the review of the Matrix M-Stage's sound signature all applies here. This is a fantastic amp for the price! Fast, dynamic, and works well with all my headphones.
Currently I have mine set at gain 0 and it really brings my ATH-W1000X to life. The bass goes low and hits effortlessly and the mids, while still forward are smooth. The HD650 also sounds great at gain 0!
This is a steal at around $100 shipped for a finished board. If you have a little DIY experience or want to get your feet wet without the complexities of putting together an entire amp this is a great start!
Thanks to JiggaD369 for compiling a list of mods mention in this thread!
I basically went through the entire thread about three times in order to condense all of the info. This is basically my first complete DIY modding project and mostly out of curiosity. It was painful but worth it IMO!
Below are the mods with Newark/Farnell part numbers (otherwise noted):
Replaced the two 4700uf caps with United KMH caps (16M6799).
Replaced the ADJ caps with Sprague10uf tantalums (30C8841).
Replaced the R2 resistors with zener diodes as per BlaBla method (18C6023).
Replaced the regulators with Fairchild (58K8936/58K8937).
Replaced the four transistor 470uf caps with Panasonic FC (80K8337).
Bypassed input caps with 6N copper wire.
Replaced the stock opamp with OPA2111KP.
Replaced the two opamp supply caps with Silmic II's.
Replaced the two small 0.022uf caps bypassing the Silmics with Philips (.027uf) Polystyrene caps. (Ebay)
Replaced the output 10 ohm resistors with Allen Bradley 1W carbon resistors (Ebay).
Replaced the 100pf caps with LCR Polystyrene caps (64K0006)
Thread Highlights & Updates
Edit 07/07/2010: Upped the gain to 10, which gives the HD650's a bit more oomph while still leaving some headroom for the W1000X's.
Edit 08/31/2010: The ebay seller now as an official site for the Lovely Cube: http://www.alicemagicbox.com/lasercollection/lovelycube.html
Edit 09/24/2010: Sunneebear creates the first balanced Lovely Cube Amp! http://www.head-fi.org/forum/thread/501046/first-impressions-lovely-cube-semi-diy-amp-lehmann-black-cube-linear-clone/75#post_6948982
Edit 10/01/2010: Comparison between Lovely Cube and Matrix M-Stage with the HE-5: http://www.head-fi.org/forum/thread/501046/first-impressions-lovely-cube-semi-diy-amp-lehmann-black-cube-linear-clone/105#post_6964362
Edit 10/13/2010: ebay seller now has OPA627AU and Class A adapters available. Nichicon KG Gold Tune 4700uF 50V replaces the Elna for Audio 4700uF 35V caps on new units. Some pictures by aspenx http://www.head-fi.org/forum/thread/501046/first-impressions-lovely-cube-semi-diy-amp-lehmann-black-cube-linear-clone/105#post_6990039
Edit 11/14/2010: Removed output caps replaced with solid core wire, opens up sound stage a bit and increases treble extension.
Edit 11/29/2010: Is your Lovely Cube case feeling very warm? Relax, it's suppose to be that way: http://www.alicemagicbox.com/lasercollection/lovelycubesecretofheat.html
Edit 01/16/2015: Corrected and updated schematics. Thanks Habibelhabab! http://www.head-fi.org/t/501046/the-lovely-cube-headphone-amp-lehmann-black-cube-linear-clone/1170#post_11021088
More technical discussion from diyaudio.com:
Some board were found with manufacturing defects that caused persistent hum. This thread offers a solution:
Edited by francisdemarte - 6/10/16 at 3:53pm