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Tone Capacitors for Stratocaster, Part 3

Applying Dirk''s cap knowledge to a real-life situation.

Hello, and welcome back to Mod Garage. To start this last installment about tone capacitors for Strats, I would like to tell you a story that happened to me some years ago. I swear it’s all true. Hopefully you will not send me to the stake after reading it—and no voodoo, either, please!

One of our customers, a professional guitarist from Switzerland, called and wanted to bring in a vintage guitar he had acquired a few days before, because “there was something wrong with the electronics.” When he arrived and opened up the case, there it was: a 1962 Stratocaster in all its glory! The guitar had obviously been played a lot, but other than a bunch of dings it was in very good condition. The previous owner had said it didn’t sound very good and sold it at a price our customer couldn’t pass up.

First Nirvana, Then Blah
I took it out of the case, tuned it, and noodled on a few chords and licks without plugging in. I was instantly stunned: It was one of the most acoustically vibrant guitars I’d ever played! The whole thing resonated—from the end of the body up to the headstock—you could even feel some notes when you touched the headstock. The overtones seemed to jump out of this guitar. I was in playing heaven.

However, after plugging the guitar into an amp, I was really disappointed. It didn’t sound bad—and the tone was noticeably Strat-y—but it was far away from being a fantastic-sounding guitar. None of the superb acoustic qualities were there. It just sounded average. As you may know, buying a vintage guitar does not guarantee good vintage tone. Over the years I’ve seen a lot of lemons from the Golden Age of guitar building, so I thought maybe this could be one of those guitars. I plugged it into my 1959 Bassman using a high-quality guitar cable, but the result was the same. I agreed with the customer that there had to be something wrong with the electronics. After unstringing the guitar, we opened it and found that most of the electronics were stock. There was one replaced tone pot, an Orange Drop tone capacitor, and a new ground wire running from the tremolo compartment to the case of the volume pot. That’s it, nothing too special. Pots can fail after such a long time, wires can break, and replacement tone caps are nothing uncommon. The pickups, switch, wiring, two of the three pots, and the output jack were absolutely stock.

The Ol’ Pickguard-Swap Test
My next step was to take out the pickguard, including the output jack, and put in an already-wired replacement pickguard that we use as a reference for testing. This pickguard is loaded with standard parts like CTS pots, a CRL 5-way switch, and a set of Fender 57/62 pickups. The goal was to create an average-quality pickguard for testing—nothing too fancy and nothing below average. After connecting everything and restringing the guitar, we plugged it in and it blew me away! Without any adjustment of the pickup heights, the sound was fantastic. Very transparent, punchy, and with all of the vintage Strat attributes we love. Our customer was totally freaking over how good the guitar sounded, and it took me some time to convince him to lay down the guitar again. You all know this special moment—playing and hearing your new guitar for the first time. It always brings a huge smile to your face. I guess you all know what happened then…after some adjustments, our test pickguard remained on the Strat as a loan while we promised to check and repair the original electronics.

CSI: Germany
To double-check everything, I temporarily installed the vintage pickguard on one of our test guitars, a standard Made-in-Mexico Fender Stratocaster. The result was the same. The tone was average and had no personality. I took some high-resolution pics for reference and then pulled all the parts out of the pickguard to test them. To make sure the pickups were OK, I soldered them, one by one, directly to the output jack. They all sounded fantastic. So it was clear that the pickups were fine and that the failure was somewhere in the wiring and/or the switches or pots. After unsoldering everything, I measured all the wires. They seemed OK. Same with the switch, the pots, the cap, and the output jack. After repeating all the checks again, I decided to reinstall everything and exchange one part after another to track down the faulty piece. After carefully reassembling all the guts, I was hit between the eyes: I put the pickguard on our test Strat and it sounded rich and beautiful— simply stunning. I tried to replicate the problem several times but failed. The guitar sounded great, and I had no clue why.

I compared the wiring and the arrangement of the parts with the pics I took several times, but it was all identical. I even marked all the wires to put them in the same place again.

Well, such things happen from time to time. The most important thing was that the failure was gone, which would guarantee me a satisfied customer. But the obscure phenomenon bothered me. So I let it cool down for a few days and then carefully compared everything with the pictures again. And there it was: I hadn’t noticed it before—because it shouldn’t make a difference—but I had installed the tone cap face up (so you can read what is printed on it, which makes things easier because you can clearly see the value). In the original configuration, the same cap had been installed face down, so it was 180 degrees reversed. I didn’t pay attention to this fact because Orange Drop caps are film/foil caps and don´t have an orientation like electrolytic caps. So the way they’re installed should not make a difference in tone. Since this was the only noticeable difference I could detect, I decided to test my own wits one more time. I reversed the cap the way it was originally installed, and I could hardly believe it: I plugged the guitar in and the average tone was back! It was like the life had been sucked out of it again.

An Orange Drop in the Forensics Lab
I wondered if the cap was faulty, so I tested it with a DMM and a scope but couldn´t find a problem. I handed the cap to a friend of mine who works at a test lab at the local university, and he did several intensive tests but couldn´t find anything unusual. It was in perfect working condition.

To find out how to avoid this same problem with your tone caps, stay tuned for next month´s column.

Until then, keep on modding!

Dirk Wacker
Dirk Wacker lives in Germany and has been addicted to all kinds of guitars since the age of 5. He is fascinated by anything related to old Fender guitars and amps. He plays country, rockabilly, surf, and Nashville styles in two bands, works regularly as a studio musician for a local studio, and writes for several guitar mags. He is also a hardcore DIY-er for guitars, amps, and stompboxes, and he runs an extensive webpage——on the subject.