For those who crave even more than Crack - Speedball

[Doc B.]

Here is a pic of the new constant current source upgrade for the Crack kit that we have been talking about. Two small Camille Cascode Constant Current Sources are installed in place of the plate load resistors on the 12AU7 input triodes, and two big and beefy ones complete with heatsinks are installed in place of the cathode load resistors of the 6080 triodes.

For those looking for something even stronger than Crack - quicker, more quiet, better mids, better bass, better resolution.

$99.

We'll have a pre-order page up soon, and I hope to have it all together to begin shipping in three weeks.

Scared to try a Speedball? Once you try it, you will understand why people get hooked.

The order page is up, so get Crack, er, get Speedballing!

http://www.bottlehead.com/store.php?crn=44&rn=446&action=show_detail

[ironbut]

Nice! You guys have been hoppin' up in Poulsbo.
It looks like there's plenty of room left in there too.

[Doc B.]

We will be re-shooting the assembly instructions today, using the actual PC boards that will be shipped in the kit rather than the prototype we used the first time around. Hope to have this all wrapped up and the first orders ready to ship by Friday.

[Doc B.]

Running just a bit behind, but I just finished the manual and we should be packing the first kits Monday!

[Blobby]

Just enquiring if the Speedball upgrade comes with detailed instructions.  I've just built a Crack amp (as part of an Australian group buy) and have got the DIY bug.  I was very impressed with the instructions that came with the Crack.   

[Doc B.]

Yup, same kind of manual as Crack.

[Mucker]

I just completed the Speedball upgrade ............. phenomenal! The improvements advertised are spot on. The Crack with Speedball is brilliant, it is getting more airplay right now than my WA2 ...... I just love the Bottlehead amp......thanks for providing such a low cost high quality solution......awesome!

[[email protected]]

Speedball question.

With the emphasis on CCCC power supplies on the circuit board, might the effect of a Speedball unit be analogous to a mains conditioning power supply?

Thank you in anticipation of your reply,

Andrew

[Paul Birkeland]

With the emphasis on CCCC power supplies on the circuit board,

What does this mean? The Speedball is not a power supply.

might the effect of a Speedball unit be analogous to a mains conditioning power supply?

I would struggle to draw a parallel.

[Deke609]

This may be more info than you're looking for, but I find the following link does a good job of explaining how a CCS (constant current source) makes a close to ideal plate load: http://wtfamps.com/ccss-and-loadlines/

Even if you don't want to get into the whole business of load lines, the graphs help you appreciate the "linearity" (low distortion) of a tube when ccs-loaded versus resistor-loaded. The curved lines represent different input signal voltages to the tube (don't worry about the tube current y-axis for now -- since a CCS produces a constant current it kinda/mostly takes current out of the equation). The bottom axis values are your signal voltage outputs - the music signal that the tube produces. Ideally, you want a linear relationship between input voltage and output voltage - for example, Vout = 50 x Vin (I've chosen the 50:1 ratio arbitrarily just to illustrate the point). That would mean that for every increase or decrease of 1V signal at the input of the tube (the grid), the output voltage of the tube (at the plate) increases or decreases by 50V.  On a plate curve graph, that kind of perfect linear relationship would show itself as an even spacing (distance) between the curved lines along the intersecting operating line (here the dashed green line).  If the spacing is big at one end of the line but small at the other (as it is with resistor loading in the linked graphs), then you have a non-linear relationship and more distortion.

All that said, this kind of distortion can sound pretty good to some ears sometimes. Some people (but it seems only a small minority) prefer the sound of a resistor loaded Crack over a speedball loaded one.

cheers, Derek