Let's take a look at the wiring and internal structure of our project guitar and make some exchanges before aging.
Hello, and welcome back to Mod Garage. This month, we will continue our aging series ["DIY Relic'ing: Break the Shine"] that we started in May 2020. Let's take a closer look at the electronics of our Harley Benton DC-Junior guitar, which is a copy of the Gibson Les Paul Junior double-cut guitar, and consider some parts exchange before we continue to keep it. If you need a review, we have introduced the aging of pickup trucks in the last part of this series ["Mod Garage: DIY Relic'ing—P-90 Pickup’s Aging"].
When aging the body and neck of this guitar (we will introduce later in this series), it is important to remove everything that is detachable from the guitar, so I took out all the electronic equipment . Looking closely at the removed inner tank, I found two metric standard (24 mm) potentiometers from Alpha Company: a 500k linear potentiometer for volume and a 500k audio potentiometer for tone. There is a 0.022 uF polyester film cap, all connected with a plastic-coated shielded wire. I also found a small budget output jack connected to a plastic-coated shielded wire.
The guitar's circuit is wired in a typical "modern" style, and you can view it on Roswell's website, the company that makes P-90 pickups on this guitar.
Although the overall quality of the electronic equipment is not bad, you can still add some headroom to enhance everything and make it closer to the retro Les Paul Junior sound we want. To improve usability, here is a list of electronic equipment and optional modules that I used to adjust this guitar. You can see the picture of "guts" in Figure 1.
Using two 500k potentiometers follows the original formula of Les Paul Junior, but there is no point in using a linear volume potentiometer in a passive guitar circuit. It should have two audio potentiometers for better usability, preferably with a taper of 60:40 or at least 70:30. In the last part of this series on pickup aging, we discussed the treble response of the pickup.
If you decide to keep stock pickups like me, it is best to use a mixed configuration with 250k volume and 500k audio to get the best of both worlds. The 250k potentiometer will slightly smooth the high end, and, as a positive side effect, the sweep control is much better compared to the 500k potentiometer with the same taper-this is the essence of passive beasts. I decided to use two American inch measurement military-grade audio potentiometers with a 60:40 taper: 250k in volume and 500k in pitch.
In order for these pots to fit, you must slightly enlarge the metric hole on the guitar. You can do this easily with a reamer or a simple half-round file. Because it's just a little bit, you should stay away from any other methods! To minimize the risk of damaging the wood, do not use drill presses with ultra-sharp milling bits, etc.
Although 0.022 uF is the standard for single-coil pickups, if you want to be as close as possible to Les Paul Junior (0.02 uF), this is the correct value, but I decided to change the sound cap and convert the pitch control to temperature control-we were in Introduced in Mod Garage. I decided to use a NOS military grade 3300 pF oil paper cap on this guitar, which will add some charm to the sound. Due to the extremely low capacitance, the high-end and treble response of the pickup can be fine-tuned very accurately. If you want an ultra-dark jazz tone, you should keep the value of 0.022 uF. If you want, this is a vast area where you can experiment. Gibson also used oil-paper sound caps in their early Juniors-the famous Sprague "Black Beauty" caps.
Image courtesy of singlecoil.com
Although the plastic covered wire tube works well, I decided to use a retro material from the 50s, just like the original guitar: cloth covered wire.
The original old-fashioned wire was AWG22 7-strand tinned copper wire, consisting of 7 individually tinned and stranded copper wires, with a braided Celanese outer wrap, and then a wax wool outer braid. Such wires can be reissued from several companies. I also decided to skip the plastic-coated wire from the volume potentiometer to the output jack, just like in the original wiring, and use a shielded braided wire. The length of this line is very short, so there is little chance of hum and noise mixing in. If you want to be as close as possible to the original look, please use wiring and shielded braided wires to connect the output jacks.
The quality of the stock mini output jack is very good, but in terms of reliability and longevity, it is a good idea to upgrade it to a full-size version.
The early Juniors set the wiring of the 50s, which is part of their special tone, which is different from the modern wiring style brought by our Harley Benton. Because when I reassembled this guitar, I had to rewire it, so I decided to convert it to the traditional 50s wiring, as shown in Figure 1. This is also the reason why I decided not to use the extra tweeter network volume pot. Usually, when the volume is rolled back, the treble response is as perfect as the traditional 50s wiring.
With US inch potentiometers, stock metric knobs will no longer fit, so you need to buy new knobs for your guitar. Looking closely at the inventory knobs, Harley Benton used the correct historically correct knobs (black "top hat" with bright numbers), but the size of the numbers is incorrect (too big), and the printed numbers are pure white. Over the years, the numbers on the knobs of old guitars have often turned pale yellow-when you have a knob with pure white printing, it is difficult (but not impossible) to imitate. So, I decided to buy a new pair of knobs, which fit the American inch flower pots and have the correct size yellow color-changing embossed numbers. You can clearly see the difference between the two knobs in Figure 2. The stock knobs are made of modern plastic, while the new knobs use vintage materials from the 50s: fully colored cellulose acetate butyrate (CAB). In addition to the different appearance, the feel is also different.
This guitar does not have any pointers, but for a more retro look, I decided to add them. Be careful to obtain a pointer with the correct hole for your pot (metric or US inches). Enlarging a hole that is too small is not an interesting project. The retro correct is the nickel pointer with a 90-degree pointed arrow tip. Personally, I don't like these very sharp pointers because the risk of injury is high. I know some players who have severely cut their hands. To avoid this, I prefer blunt pointers with rounded tips and minimize the risk of injury to you.
Gibson used a nitrate 3-layer (black/cream/black) jack plate on their early Juniors, while our Harley Benton guitar was equipped with a single-layer solid black jack plate. Initially, I wanted to replace the jack plate with a retro correct jack, but when doing so, I realized that the Gibson jack plate is not suitable for Harley Benton with a smaller jack plate. Of course, you can use the correct 3-layer material to make a custom jack board, using the original as a pattern, but I decided to simply leave the original jack board on the guitar, sacrificing some retro look. Because I decided to upgrade the output jack to a full-size version, I had to use a reamer to slightly enlarge the hole on the board. The four stock screws are chrome plated, so I decided to replace them with a nickel version, which will provide a more realistic appearance when they are aged later.
Gibson used a black nitrate single-layer backing sheet in the 1950s. Harley Benton did the same thing, but using modern plastic materials. This is no problem for me, it looks very close to the original after a little aging. The two stock screws are chrome plated, so I decided to replace them with a nickel version to look more real when they age.
That's it for the time being. In the next part of this series, we will introduce the aging process of the hardware components listed above and take a closer look at the guard.
Until then... continue to modify!