#BOTTLEHEAD CRACK SPEEDBALL UPGRADE#

Unbalanced cables Worlds Best Cable Gotham GAC-2 RCAĤ. The data presented were collected as follows:ġ. Interpretation of the following measurements is beyond the scope of this post. There are other useful publications as well. Cabot and also by Bob Metzler, both from Audio Precision. 'audio measurements' or 'audio measurement handbook' But I’ll get back to that in my review of the Bottlehead Crack.If you are unfamiliar with audio measurements please use a search engine with the query:

#BOTTLEHEAD CRACK SPEEDBALL UPGRADE#

This is what the finished installation of a Speedball upgrade looks like.Īfter doing another round of voltage checks on the Bottlehead Crack and Speedball upgrade, the new and improved Crack was fired up. My kit was missing two screws for the main PCB, but a couple of HDD screws did the job nicely, although a little bit of a tight fit. There isn’t much room to connect the wires to the boards. The standoffs is supporting the PCBs nicely. After some heavy negotiations, there is room enough for the standoff.īlack and red teflon wires basically have to go where all the resistors used to be, because the Speedball upgrade is going to do the same job they did, but hopefully a better one. Â The standoff between the nine pin socket and the terminal strip is VERY hard to fit, because of all the solid core wires going through this very spot. Nylon standoffs are installed in front of the octal socket and and around the nine pin socket. The Speedball upgrade makes the plate 22k1 load resistors redundant and they need to go, along with the 3k cathode resistors. Your precious Crack needs to be partly deconstructed, to make room for the Speedball upgrade. But let’s start with how these circuits is added to the Bottlehead Crack design. Faster, deeper bass, more detailed and wider soundstage and dead silent background. The most important thing here is that the Speedball upgrade makes a huge difference. The good news is that you don’t have to understand this, to enjoy and appreciate the Speedball upgrade or even to make it yourself. Pretty technical stuff, or at least it is to me. Isolation from the power supply also removes the powerÂ supply capacitors from the signal current loop.” It is otherwise extremely difficult to stop RFI that is carried on the power line,Â because power supply chokes have a leakage capacitance and the large capacitors used will alsoÂ have some inductance at high frequencies. A goodÂ current source will provide a high impedance over a wide range of frequencies including radio frequencyÂ interference.

A second advantage, not as widely appreciated,Â is that the current source provides a great deal of isolation from the power supply. “A Camille Cascode Constant Current Source is applied to each triodeâ€”both halves of the 12AU7Â voltage amplifiers and both halves of the 6080 cathode followers.Â By loading a triode voltage amplifier with a high impedance, such as an active current source, it operatesÂ in a more linear region and produces less distortion. It’s quite difficult to explain in technical therms what the Speedball upgrade is all about, but it’s basically about feeding the tubes in a more linear way, resulting in a more dynamic sound, rather than one controlled by available and changing current. So of course I wanted to hear that for myself.Â Bottlehead recommends building the default Crack and make sure it works properly before moving on to the Speedball upgrade, so this is why I have done so. Everybody that tried it, including reviews, said it was a night and day difference from the default Crack setup, and that you basically had to upgrade it.

When I ordered my Bottlehead Crack kit, I also ordered the Speedball upgrade right away.

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