Bottlehead Crack build log: Completed

Bottlehead Crack build log: Started building

I got sick of trying to figure out a powder coater and trying to find a mill, so I just started assembling last night.  I spent about 6 hours putting it together.  I was so tired when I was finished I could barely keep my eyes open or even mentally focus to find a power cord.  The only thing I didn't finish was wiring in the power button.  When I fired it up the tubes glowed, but no LEDs lit up.  I looked at the schematic and figured that there was no high voltage being supplied to the tubes, so I tested the supply.  Nothing.  I traced my wiring and noticed that I forgot to solder the wirewound resistor lead to 13L.  I soldered it up, fired it back up, and everything lit up like it should.  I plugged in my headphones and there was a pretty loud hiss going on, but after a minute it quieted down completely.  It sounds slightly better than before due to the Speedball.  It's been months since I've heard it, so it's impossible to be certain what difference it made.  I only got to snap one picture of a bunch of stuff mounted to the top plate.  I ran out of #4-40 torx screws, so I am going to wait until I receive the rest of them to take the final pictures.  I regret going with this silver-plated stranded wire.  Even tinned, it was a pain in the ass to wrap around terminals.

Bottlehead Crack build log: PCB mounting

I went ahead and made an order to McMaster-Carr yesterday and I got my hardware today.  Part of the order was to replace the standoffs that came with the Speedball to hex-shaped jawns.  The ones from the Speedball I drilled out and turned into the short spacers you see between the PCB and transformer bracket.  Now all that awaits is trying to find a powder coater with the color I want and someone who will let me use a mill with my bit for a few minutes.

Bottlehead Crack build log: End mill

7mm end mill for the Neutrik indent.  7mm is the exact radius of the corners.

Bottlehead Crack build log: 9-pin CNCed bracket

I got the tube socket bracket from the machinist and polished it a little.  It was machined by Accurate CNC Services in Idaho.

Bottlehead Crack build log: Speedball assembly complete

I got the board in the mail yesterday.  I really enjoyed putting this together, and I was skeptical of the posts for the heat sinks being able to be soldered.  I also took a picture of the on/off circuit PCB and the Alps PCB I made.

Bottlehead Crack build log: Speedball ½ built

The Speedball is half built.  They accidentally sent me two small boards and a small board before it's split apart.  Just waiting on the proper board to arrive.  I'm glad for the error because I didn't care for how they split the board.  It looks like it was cut with something that incises instead of something like a saw, so I was able to split my own and I used a hack saw to get a nice edge.  I still need to buy a powder coating kit, a toaster oven, and all of the Torx hardware from McMaster-Carr.  A company is CNCing the bracket I designed for the 9-pin socket.  The only other thing I need to do before I can sit down and start assembling is to machine (find someone to let me use a mill) an indent into the top plate for the headphone jack.

Bottlehead Crack build log: On/off PCB assembled

I got the PCBs made.  They sent me 10 instead of 1.  If anyone wants to buy one or more, contact me.

Bottlehead Crack build log: Laser-cut top plate

I got the top plate from the laser cutter today.  This is it after some wet sanding.

I got the plate cut at Smucker Laser Cutting & Metal Fabrication, located in Lancaster, PA.

Bottlehead Crack build log: On/off circuit progress

Finally, some real progress:

The transistor idea didn't work, neither.  I ended up just adding another output to the program.

Parts List

Bottlehead Crack build log: Breadboarding and circuit ideas

I got this on/off circuit set up on a breadboard today.  The stupid voltage divider didn't work for the LEDs, so I have to try to use two transistors to control the LEDs.  They are inside of the switch, by the way.  I need to really start posting some pictures up here.  Here is the new schematic.  I haven't bought the transistors yet, but I am going to get some at RadioShack tomorrow.  It should work, in theory.

Bottlehead Crack build log: PIC programmer

Well, I got this PIC programmer, and with the help of this guy from the microchip forums named Dario Greggio I got the PIC to act as an on/off toggle with the off action requiring a button to be held down for a few seconds.  I've since designed the PCB for the circuit.  If anyone is interested in the circuit, PM me for more details.  Getting a quantity of PCBs ordered would bring down the cost, greatly.  I will draw and post up the schematic here later.

Bottlehead Crack build log: 9-pin socket LED soldering

I was bored and felt like soldering the LEDs and ground wire to the center post I made.

Bottlehead Crack build log: Teardown, top plate design, and capacitor brackets

I got it all torn down days ago.  I haven't decided if I am going to get another top plate laser cut or just modify this one.  I want to go with a Bulgin switch, and not in the stock location.  It's in a bad location where I have the amp sit I burn myself on the tube reaching for the switch to turn it off.  I have a top plate designed in AutoCAD.  I'm just waiting to hear from a place about laser cutting and if I need to add any considerations for beam width (maybe someone here could help me?).  I drew everything literally the size I want it to wind up.  The new tube sockets are smaller in diameter, so I ended up shrinking those holes in the drawing.  I will still need a few more holes to mount a board that does the on/off latching and delays the signal to the headphones because I don't feel like putting the massive effort into pressing the latch to remove the headphones every time I turn it off, and I don't feel comfortable leaving them plugged in when I power it on.

The transformer end bell ended up ugly and rusty with all of the skin oils from handling.  Oh well.  That's getting powder coated and it was the plan from the get-go.

I got the capacitor brackets from Shapeways today.

Bottlehead Crack deconstruction and build log

I bought a Crack off ebay some time ago, pre-built.  It came with AΞON output capacitors.  I've since replaced the RCAs with Neutrik ones and the headphone jack with a Neutrik latching jawn.  The octal tube socket just plain sucks and the signal started becoming intermittent, so I took the amp out of commission and I am going to do a whole slew of things to it.

  • I ordered new tube sockets.  They are the teflon composite type from Parts Connexion.  They have a silver-plated crown springs inside the contacts made of beryllium copper.
  • The capacitors came dangling.  I just used packing tape to keep them held up.  It works and can't easily be seen because it's clear.  It's not ideal so I designed some brackets in SketchUp and are having them made at shapeways for $3.96 apiece.  They made specifically for my capacitors, and you can see the slots for the zip tie.  Click this sentence to visit the site and maybe purchase them. I don't get anything for it.  I designed them and put them up for everybody.
  • The headphone jack is crooked and could use some mounting work.  I am going to look for a machinist to just nip into the top plate a tiny bit to the shape of the jack's flange so it absolutely will not move.
  • I am replacing all hardware with torx hardware.  I haven't found a place where I can get all the same alloy for all of the sizes I need and inexpensive.  McMaster-Carr has them all for cheap, but in different alloys.  Aaron's has any size you can imagine and in whatever alloy you want, but small quantities are expensive.  I would maybe go for larger quantities if people would go in on a buy (hint hint).  Fastenal doesn't really have anything, anymore.
  • I am going to have the top plate and transformer end bell powder coated.
  • I am looking to add in an audio spectrum analyzer circuit I bought some time ago.  I would like it to be after the volume control.  Will there be any impedance problems?
  • I am looking to add a timed relay circuit that won't connect the headphone output at power on until a set amount of time.
  • The Speedball upgrade will be done.  What hardware does that kit use?  If I have excess quantities from the bulk I order for the Crack itself it would be nice to have these used for mounting the Speedball.
  • I am thinking about solid silver wire with cloth insulation, and not with PVC or teflon innards.  Does anyone know of a place that sells a decent selection of sizes and colors (red, white, and black)?  I found a place in the UK, but I would prefer somewhere in North America.

So far I'm impressed with the amp.  I didn't think the sound would change that much from the on-board amp on my STX card.  Naysayers obviously don't understand that impedance is only measured at one frequency point and high-impedance headphones like my HD-650s are quite demanding of power for bass.  You need a healthy reserve of power to drive low frequencies. More Updates to come.