Friday, November 16, 2012

Fender Excelsior tone pod mod

  I've been on a bit of a tone search trip lately. I always had almost as big interest on the tone of guitar as I did in the playing of it. Also in the nature of this blog and just plain simple restrictions of finances, I am always aware of how much I spend on my equipment. But even more so I am always looking for something new in tone, something you just can't buy from your local music store. You see, there are these musicians who have the best of the best equipment and all I say is good on you. But I find if our goal is to buy the Gibson Les Paul Custom and Mesa boogie triple rectifier (you can replace the guitar and the amp for any top end make here), more and more things will start to sound the same.
 I know I am not alone in this search and for those of us not too impressed by the perfection of a €2000 off the shelf amp are left with few options. You can go the vintage rout, look for that magical 30 year old amp or guitar, which in many cases is over priced. I personally like the idea of actually customizing my tone.


  So earlier this year I came across a new amp from Fender that got me bit exited (we've all been there). The amp in question is Fender Excelsior. Amp made in style of 1950s catalogue amps. It is a simple amp, with three inputs. Volume and tremolo controls and single dark to bright tone switch. It is full valve (tube for our american friends) design 13 watts and projects the sound from a single 15 inch speaker. The thing about this amp is that it is not trying to sound like any other amp, it has a tone of its own. But also it is designed to be a great platform for modifications.
  After doing my usual research that I do before purchasing any new equipment, I got a great deal and decided to purchase the amp. On my purchase I was very impressed with the amp, but still I knew I was going to alter the amp to get a tone that is more what I had in mind. The first short fall of the amp is the dark to bright tone switch. The bright is pretty shrilly and piercing tone and the dark is lacking in clarity. It was clear from the beginning that the ideal tone from the amp would be some where between the two. So I decided change the switch in to a tone pot. I do need to say here that any one doing this will straight away cancel
out their warranty on the amp. But I had run the amp through it paces and knew it was working fine. If something was to go, it would be something that could be fixed by any good amp tech (also another beauty of the simple design of this amp). I used to have a Fender blues junior, a great little amp. But I was never impressed with this amps internal design. I had a problem with the input jack and one of the valve sockets, which were bot attached to the circuit board that was very tightly designed. To be honest with you, I actually had one look inside and decided the blues junior. But the Fender Excelsior's insides are much more modification friendly. There is loads room inside and the power and pre amp sections are housed separately. If you are more interested in the inner workings of this amp, I recommend you take a look at Billm's website and especially his page on Excelsior

  Anyway, so I had a spare 500k pot in my spare parts, and decided to open the amp up. As I mentioned earlier the pre amp part is separate from the power amp part, so opening the amp was very easy. Two screws on top of the amp and I had the pre amp chassis in my hands. Few more screws and I had it opened up. Inside I could find the dark bright tone switch that has three cables attached to it. I carefully desoldered them and attached them to the pot exactly the same order as they were in the switch. It took little bit of filing to fit the pot in to the hole of the old switch. I also had an old control knob, that nicely covered the screw holes that held the switch. It's not exactly the style of the other two knobs, so I might look for some new knobs, kind of like the idea of cream colored chickenheads. When I started opening the amp, stuck the Black presidents CD on, and by the time I had it done, the album just finished, so just over half an hour it took me and the difference with the tone control is amazing! It really makes this amp very flexible for its three control design.
  Just a small warning here. I would not call my self an expert in electronics, but I knew what I was doing before I opened the amp up. There can be potentially lethal charge in a valve amp. So make sure you know what you are doing! Once again Billm's website has been a wealth of information for me, so check it out at www.billmaudio.com and especially his page on discharging capacitors. This is an easy modification, but you can potentially do permanent damage to your amp, so don't tell me I didn't warn you. As mentioned above, if you do this the manufacturers warranty is gone! So if you are worried about this, either don't do it, or wait until the warranty is out. Personally for me I bought this amp as much for playing and gigging as to learn the insides of an simple valve amp, so I wasn't worried about this.





    So there it is. The first mod on a journey to my own tone. I am also tinkering with the oldest and cheapest Boss distortion pedal DS-1. The results so far are great! So I'll be sharing some of these with you in the future as well. Great tone on a shoestring ;-) and best of all, my own tone.
  J.P.









Glory to the World - Single - J.P. Kallio

5 comments:

  1. Just bought one also and planning to do the very same mod. Furthermore, Eminence Legend will also replace original speaker (Fender uses it for Excelsior Pro - model) and some tube exercise will take place.

    Well - it's not up to my -72 Silverface Fender Quad Reverb, but a such nice amp for quite little money and far easier to carry around.

    Regs,

    Janne N. / Muurame

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  2. Amen to the tone search. Did the tone switch mod, and it was a definite improvement. I'm not one to leave well enough alone, and immediately wondered if I could go one step further..a treble/bass tone stack. After studying the Excelsior's schematic and a Bassman AB165 chassis layout, I bought a 250k/250k concentric pot,soldered a jumper wire to the middle terminal of both pots, and the middle wire from the tone switch to the middle(input)terminal of the top pot, then each of the other 2 wires from the switch to the right-hand terminals of each of the concentric pots. Since there is a separate "mini circuit" for each side of the original tone switch, my setup gave a variable resistance to both the "bright" and "dark" sides. In other words, a treble/bass tone stack.It's a subtle variability, and I imagine 500k/500k would be more dramatic. But I really like the additional tone possibilities. There's enough room for a mini-pot or regular size concentric. Haven't found anywhere online that someone else has tried it. So the tone-search continues! It sounds awesome with a Tele. My name is Tony(get it..TONE-EE) tkeiser@cox.net

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  3. Hey man!
    Thanks a lot for nice info on the Fender Excelsior!
    I´ve been toying the tone-pot idea for a while - and I did it today with the help of your simple explanation and pics!
    It´s´a nice upgrade over the 3-way-switch and I recommend it to anyone contemplating the idea! I´m not a tech-wizzard by any means, but I had a matching pot and knob in my drawer and the mod took me 10 minutes or so.

    Thanks a lot for your hep and keep rockin´

    - 68.

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    Replies
    1. Great to hear! Yeah, it's such a simple mod that makes all the difference, really opens up the amp.

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  4. Picked up this amp at a pawn shop last week, swapped out the speaker for a Peavey Blue Marvel last night, Tone Pot mod next and JJ tubes are in order. Thanks so much for the how-to!

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