Excelsior Tone Control

The second version of the Excelsior tone control is now available! Go to the end of the Mod Kits and Services page if you wish to order it.

This is the second version of the “real” tone control, and it gives you a full range of tones, from dark and thick to very bright. You can pull up on the tone control to bypass it completely and get the amp’s raw tone. You can hear this version of the control in the video at the bottom of this page.

Here’s a little background:

The Excelsior was designed to be an offbeat, oddball amp from the start. The bright-dark switch is just one of the goofy design decisions that makes the amp fun, but also limits it.

One of my first mods was to substitute a 500K pot for the switch, to make the transition from the bright to the dark setting continually adjustable. You can hear the effects of that mod in this video:

It’s not bad, but the range of tones is somewhat limited, especially on the bass end. I felt there were better-sounding versions of the single-knob tone control. In the videos below, I test two versions of the same control. I designed it so all the components are mounted on the control, and there’s a pull-up to bypass the control and get raw tone. The control attaches to the existing circuit with two wires. Other than removing the switch, there are no other modifications required.

It’s hard to capture amp tone with a camcorder, but I also don’t have the time to properly mic the amp and mix it into the video. (I tried an external SM58 plugged into the camcorder, but there was a lot of hum.) To hear these recordings properly, you need earphones or good speakers. From the emails and messages I received, the votes were unanimous for the second version.

Click for larger image.

Click for larger image.

Installation of the tone control is fairly easy. All of the components are mounted on the control and pull-up switch, and it attaches to the Excelsior with two solder connections. You don’t have to remove any components from the circuit board. There is no clipping or cutting. Just desolder the switch, enlarge the slot slightly with a file, and install the control according to the provided instructions. I supply the brown vintage-style knob with the kit.

By the way, the white lines on the knobs are 1/16 inch pinstriping tape. I got tired of not being able to see the molded pointers.

Here is the first version:

And here is the second version:


  1. tjnugent says:

    I like the wideness of version 2 better. Nice job…

  2. tjnugent says:

    The tremolo is better on version 2 as well. More depth to my ears.

  3. snk says:

    Version 2 difinitely sounds more open and wide. The pull-up option is very nice, will be useful when plugging in external EQs and preamps. And such a simple installation!
    Brilliant mod, I’d like to have it in my amp.

  4. TheOrangeRoomStudios says:

    I definitely like the version 2 tone control…I would take mine regular 500k pot out and install yours when ever you make it available. I agree with your comment: “The excelsior as its designed, doesn’t put out enough low bass, despite the 15′ speaker.” Hopefully some mods will be coming to fatten up the bass response. I have tried the 15 legend speaker with couple other amps and it has the potential to have more tight bottom end. As a result of the “lack of low end” I have found that when using any distortion pedal (too many to list) with this amp the low end vanishes.

  5. daveyboy says:

    It makes for a more versatile amp,
    All original tremolo and tone options are still essentially available.
    I wish mine was set up that way!
    As far as low end goes, the Fender bassman pedal I have seems to eq in some nice chunkiness (maybe its the presence control)?

  6. jamespeel says:

    I need that tone knob from the second clip! Are you selling it yet?

    • bill says:

      Yes, I’ve built several and prepared installation instructions, along with photos. It’s at the bottom of the Mod Kits and Services page.

  7. rockabillybob says:

    Hi Bill. Just ordered the tone control kit and looking forward to more tonal options from my Excelsior Pro. Thanks very much for making this available.

  8. BigRed says:

    I just installed the new tone control for my excelsior and I can say without a question that it was the cheapest and best upgrade I have done to the amp. The tone MOD has set the amp free.

  9. db3 says:

    Hey Bill,

    I just installed a Eminence 1518 and the tone control in my Excelsior. Big improvements for both mods. The tone pot is a welcome and well executed feature. While I was able to get the tone kit installed and working perfectly, I would like to offer some feedback on how it might be improved. Primarily what would be greatly appreciated for old guys with declining eyesight and not the steadiest of hands, is a lead from under the orange cap instead of having to solder in such a tight spot. It would be much easier to solder a wire splice. I was attempting to pre-tin the solder point, and of course ham-handedly dropped a glob of solder onto the diode below soldering it to the pot case. I was able to clean it off with a fine soldering tip, but a lead coming out of there would be so nice.

    Secondly, make to two wire sleeves heat shrink tubing so that they would adhere to the old wires, instead of sliding off. And while you are add it, add a third small piece of heat shrink tubing to use over the wire splice. Lastly, I thought about requesting two nuts so that the old switch bolts could be used to fill the empty holes, but there might be a more elegant solution, perhaps plastic plugs. Will keep a lookout in that regard.

    Otherwise perfect and very much appreciate the time and effort that you put into these kits.

    • bill says:

      I can see the advantage of the splice. My goal was to make it as simple as possible, but I agree that you need a steady hand to solder into the eyelet under the capacitor.

      Thanks for the feedback.

  10. lvaughan says:

    Got your tone pot and installed it yesterday – what a difference! It seems to me the amp is louder when the tone pot is pulled up. This inexpensive fix solved my only complaint about my Excelsior, except for having to swap out the original set of noisy tubes. New Mesa Boogie 12Ax7 and 6V6 tubes cleaned up the noise issues beautifully, and the tone pot sends the amp into new and welcome territory. Thanks for the mod, the videos and the great service.

    • bill says:

      Yes, the amp is louder when the control is pulled up because all tone controls steal some signal. When it’s pulled up, the tone control is fully bypassed and you hear the amp’s raw tone.

  11. shawn says:

    Once you remove the tone switch, the two holes that screw it in place are left unplugged, since the tone pot does not utilize them. Does anyone have any ideas for the screw holes that are left there? Is it bad to have it left open? Maybe the circuits like the extra air?

    Considering gluing the original screws in place. Silicone? Cork? Open?


    • bill says:

      The holes don’t affect anything. The original screws are probably metric, so you may have trouble finding nuts for them. You can fill the holes with US-standard 6-32 screws and nuts.

  12. shawn says:

    Thank you Bill.

    Well everything’s done on the excelsior.
    Bill, you and your web site is a great resource. What a difference all these changes made – for the better. Still, the things it lacks probably can’t ever be fixed, but as a cool looking quirky amp, it’s great.

    Legend 1518
    tone mod
    new transformer
    JJ tubes
    new speaker wire

    Since I managed this project, I may try to mod a Boss GE-7 next.

    Kind regards,

    • bill says:

      Next up: The tremolo depth mod and speed range increase. Other stuff keeps getting in the way, though.

      • shawn says:

        Life has a way of doing that! U used to say that my job is getting in the way of my personal life!! 🙂

        BTW, a splice would be good for your tone mod, like the other gentleman said. For me, that upgrade was much tougher than the speaker or the transformer mod. I kinda messed it up a bit. At least it all still works, thank God. 🙂

  13. tap4154 says:

    Bill, I’ve found that carefully pushing the stock tone slider into the mid (in-between) position bypasses both the treble cut and treble boost and opens up the tone. The bright position is far to bright for me (for SC pups), so I was thinking about just clipping or de-soldering the outside yellow (upper yellow wire in your pic above) from the tone slider switch, so the bright position would then be open. Is that correct? Then I’d just have raw/open, and dark, which is mainly what I use anyway.

    Thanks for all the information, mods and pics of this cool amp!

  14. tap4154 says:

    In the mean time, I went just ahead and snipped the wire and it works as planned. Raw tone on “bright”, the same treble cut on “dark”. Very cool ;o)

    • bill says:

      The slider is not a great substitute for a real tone control.

      • tap4154 says:

        Are there advantages to using a tone control on the amp instead of simply using the guitar’s tone control with a wide-open amp that has no tone stack?

        • bill says:

          Guitars have their own sounds and amplifiers have their own sounds. An amp with no voicing at all is very unusual. Most musicians want the amp to shape their tone to some degree.

  15. dochep says:

    Hi, Bill. I installed the tone control a few months ago and it has been a very useful alternative to the stock switch! I ran into a situation over the weekend and would love some troubleshooting insight. While playing my Tele, I was greeted by a most unpleasant distortion on the G string from the 9th to 14th frets. It was a lot like the sound of a torn car speaker with the radio turned up too high. I was able to reproduce it on my semi-hollow with Filter’Trons and with a piezo. I pulled and replaced all of the tubes — no change. I then pulled up on the tone control and the sound magically disappeared! I repeated this with each guitar with the same results.

    Any thoughts? I have not pulled the chassis out to check wiring because I wasn’t sure what I would be looking for.

    • dochep says:

      I did discover that I could get the “distortion” to disappear by engaging the tone control and dialing up to 3 o’clock.