[Maxhawk]

  So they'll include a CD with the manuals ? I didn't know about it. But then why'd they put the PDF manuals in the cart ?
Will try to email Doc now, thanks

Bottlehead no longer ships with a CD and the PDF is one-time download only. I suspect they might change the one-time policy if they get too many instances of folks not getting it the first time. I personally had to ask again since I was downloading originally on a slow, spotty connection that timed out at 30%.

 

[PETEREK]

Just got my Crack and Speedball kit in the mail. I have a week off work after tomorrow, so I will have plenty of time to get it together. I'm excited!

 

[jorgen83]

  Bottlehead no longer ships with a CD and the PDF is one-time download only. I suspect they might change the one-time policy if they get too many instances of folks not getting it the first time. I personally had to ask again since I was downloading originally on a slow, spotty connection that timed out at 30%.

 
Perhaps the Bottlehead peeps will frown on this, but I quite simply found the manual with a Google query some time before I bought the kit. 
 
That said: bought it, built it, love it! I'm still using the tubes it came with, both RCA tubes, so can't wait to see what happens when I put a 6AS7 in and a cleartop.

 

[ph0ngt3p]

   
Perhaps the Bottlehead peeps will frown on this, but I quite simply found the manual with a Google query some time before I bought the kit. 
 
That said: bought it, built it, love it! I'm still using the tubes it came with, both RCA tubes, so can't wait to see what happens when I put a 6AS7 in and a cleartop.

I've found a 6/4/10 version of the speedball manual. Is it too old ? Any major differences between this and the newer revised one ?

 

[kekoukela]

  I posted this on the Bottlehead forum, but there seems to be more activity here so I thought I'd repeat it.
 
This thread (http://bottlehead.com/smf/index.php?topic=5989.131) on the Bottlehead forum describes methods to mod the Crack to optimize bias for various tube types. I had added a switch and resistors to allow use of the 12BH7 as well as E80CC/5687 but wanted something neater and consequently more reliable long-term. Here's the before shot:

 
 
I decided to make my own PCB, integrating a DPDT switch and resistors, and condensing the dual boards into a single PCB.
Here's the bare PCB:

 

And stuffed with parts:

 

Installed in place of the 2 separate boards:

 

The first try wasn't perfect, as the mounting holes needed some dremeling to allow the PCB to clear the standoff from the other PCB. Also some of the pads are on the small side and the holes for the LEDs are too large, but it did work first time.
 
After spending more time switching between the 12BH7, and 5687, I find that the 5687 excels in imaging and placement, but is down on bass compared to the 12BH7.
 
I had to buy 10 pcs minimum and I've only got one Crack, so I've got extras if anyone is interested.

I would be VERY interested in getting one. Is it expensive?

 

[kekoukela]

  Finally finished the kit I've had sitting around since last summer!
 
This is the second Crack I've built, got a good deal on it in a group buy and wanted to build another to replace the one I've had for a few years. I took my time with it and made a few modifications right from the start:
 
-Connex Premium tube sockets
-Socket PCB adapters for easy soldering
-50K Alps Blue Velvet pot (works better than 100K with the HD650 I think)
-Cardas Quad Eutectic solder (this stuff is a dream to work with, things practically solder themselves)
 
I'm really happy with how it came out. It sounds excellent, noise is completely non-existent, even with the volume pot at maximum. I left the speedball off for now because I want to do some A/B comparisons with my other kit that has the speedball installed.
 
I'll post pics of the finished build too, I have something special in mind for the base
 

Home I'm not being too annoying, but may I ask you to take some more photos of your build? especially profile pics? I am really interested in the PCB boards idea! BEAUTIFUL

 

[FunyunBreath]

Yeah no problem! 
 
Here's some macro shots of the internals. Other than the socket PCB's you'll probably notice the 9-pin socket bracket is mounted from underneath. It took a bit of grinding to get the screws to fit properly but it gives the top of the chassis a really clean look.
 

 

 

 

 

 

 

 

[kekoukela]

Man Just beautiful work. Are you planing on installing the Speedball on this crack? Do you think the increase in height for the 8 & 9 pin sockets will affect installation of the speedball?

 

[FunyunBreath]

Thanks! Comparing my speedballed crack with this one it looks like the height on the sockets is almost the same so there shouldn't be any issues installing the boards. 
 
I've been doing A/B tests between the 2 amps and I'm still undecided on whether or not to put the speedball in. With the right tube combo in the stock crack you can get a lot of the same benefits as the SB but still keep that smooth sound.

 

[atomicbob]

  Thanks! Comparing my speedballed crack with this one it looks like the height on the sockets is almost the same so there shouldn't be any issues installing the boards. 
 
I've been doing A/B tests between the 2 amps and I'm still undecided on whether or not to put the speedball in. With the right tube combo in the stock crack you can get a lot of the same benefits as the SB but still keep that smooth sound.

Which tube combo do you feel gives you the SB advantage?
I recently changed the 12AU7 plate resistors to 50K 20 turn pots so I could experiment with other input tube families. Currently enjoying a Tungsram e80cc with a Tung-Sol 6as7g. Also replaced the 100 uF output caps with Rubycon 470 uF 160V. Major improvement in sound stage and bass performance. The improvement was also visible on oscilloscope with 20 Hz square wave source. I have before / after screen shots if anyone is interested.

 

[FunyunBreath]

My 2 favorite combos are the 5998/Amperex 12au7 and 5998/Jan Sylvania 6SN7GT (VT231)
 
It seems like the 5998 just pulls the best out of both of these tubes. When I use them with some of my other power tubes like the RCA 6AS7G, Tung Sol 7236, Sylvania 6080 the amp just loses a lot of it's clarity and dynamics.
 
Thats a cool idea with the caps, I'd be interested to see the differences.

 

[atomicbob]

Source signal DAC - Mousai MSD192 - 20 Hz square wave at RCA outputs with 10 K load.


BH Crack (non-SB) output with HD800 load - stock 100uF 160V Aluminum Electrolytic output caps


BH Crack (non-SB) output with HD800 load - Rubycon 470uF 160V Aluminum Electrolytic output caps

When I measured the capacitors on an LCR bridge, the Rubycons were almost exactly the same value while the stock caps were farther apart in value. Note how the Left and Right channels are much more tightly matched with the Rubycons. Also note how the ouput is closer to the input in waveform shape. Tubes used for this testing were Tungsram e80cc and Tung-Sol 6AS7g. Grid voltage at the 6AS7g has been adjusted to 88 Volt on each channel.
 

 

[Doc B.]

Hey Bob, nice! Are you going to try some film caps too?

 

[atomicbob]

  Hey Bob, nice! Are you going to try some film caps too?

Interesting you should ask that. A pair of 100uF 250V Dayton polypropylrne caps just arrived today.

 

[Doc B.]

Would also be interesting to see that square wave with a passive 300 ohm load.