Allan Holdsworth Harness "Test Unit #2"
By Paul Marossy
Created 12/14/23
I have been able to determine a little bit about the "super harness" in THIS J ROCKETT VIDEO
from 2013. In the image below taken by a fan at Allan's San Marcos gig (2017?), we can see that this is what Allan called "TEST UNIT #2", and is what I used to determine the value of the air core inductors quoted on my webpages. They are marked as being "1 mH each choke" on top of the unit. It appears that this rack mount box was a one size fits all unit that could be used with any kind of amp and speaker combo. We can also perhaps get a clue about how the Harness I may differ from the Harness II by looking at his notes.
The images below are extracted from the low resolution video, and while having terrible clarity, some things are apparent when we look inside. It appears that this is a dual
unit which likely can switch between a master volume amp and a non-master volume amp. Also can be used with an 8 ohm load or a 16 ohm load. All of the chokes have the
ability to be switched on or off. One of the nichrome heating elements is 8-9" long and the other one is about 12" long. I can't determine how the chokes are wired but we can see that there are a total of ten of them, and it looks like one was added so Allan had to modify the wire bobbin to make it fit. All of the circuitry is mounted on wood, which is non-conductive. I assume that this is what he may have used to determine the best combination of components for his commercially offered hand wired Harness units.
Below we can see Allan with one of his personal Juice Extractors, which has been partially gutted. It's difficult to see but it has markings on the inside which indicate
that it contains 1.5mH chokes. Also says "1.5x7" on the front. This does throw a wrench into things when it comes to determining the values of inductors used in his units. It's either 1.0mH or 1.5mH, or maybe even a combination of them. Unfortunately I can't determine that without actually having one of his units to examine. We can see that it had eight outputs, and that is reflected by the six outputs on the Rocktron Juice Extractor.
This image of the front extracted from the video appears to the same unit as shown above. There are a striking amount of switches and a few knobs. I'm not sure what the knobs
do but I know for sure the big red knob is the line level control. The permanent marker there indicates what he felt was the optimal range for that control. It appears that he made these markings on all of his personal units.
Hopefully that de-mystifies what is seen in the YouTube video. Now that I know what he was doing with these units, it's not as crazy as it looks. I'm not sure
if he was continually tinkering with these things or not, but he had at least four that he built for his own use and one that he seems to have consistently used in
the early to mid-90s. You can see that one sitting on top of the Mesa Boogie head in his 1992 REH video when they are performing Chad Wackerman's tune called "Tell Me".