Curiously Modded Fender Excelsior

kraml_1066

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Here's an Excelsior Pro that I picked up while back. Opened the (upper) chassis just now and found quite a few modded resistors (piggyback/replaced), some kind of alteration to the accordion input, and the addition of a jack on the bottom of the (upper) chassis. The amp came with a home-made external volume box that I haven't peered into yet. Anyone familiar with these mods? k ex1.jpg ex2.jpg ex3.jpg
 

Lowerleftcoast

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found quite a few modded resistors (piggyback/replaced)
R5 is the plate resistor for V1a. R7 is the plate resistor for V1b. Traditional Fender plate resistors are 100k. Paralleling the resistor here approximates that value (110k). It gives a less gritty type sound. A little less gain. This is a fairly standard mod for amps that have larger plate resistors. Like Carvin Hasserl mods.

R23 has a red wire to a jack. It appears to try to remove the first gain stage. I can't tell how this is actually wired. (I question if this wiring is well thought out. It might be fine. I just can't see what is going on.)

R16 black wire to jack, may be a foot switch for the tremolo.

I found this on website... guitarnuts2, "i added 100k resistors in parallel to R21 and R37 to slightly increase the upper bounds of the tremolo speed"

That is all I see.
 

Telekarster

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It has the tone switch-to-pot mod on it as well. I did this mod on mine as well, and it's vastly superior to the original, cheapo, POS switch they come with i.e. much more user friendly. So, that's a good upgrade to have. Good find!
 

kraml_1066

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LLC and Tele: Thanks for the responses. In the meantime, I've been doing searches such as "Fender Excelsior R5." I've actually found a single post that describes these mods to a "T." It's likely the person who modded this very amp! (See https://www.thegearpage.net/board/i...-for-excelsior-amp-mods.1290707/post-19616692.) The mods are all just as you two describe: the tone pot (of which i was aware), the oscillator switch/jack, the preamp bypass input jack. * I'm going to have to dig into the amp at some point. The amp is pretty clean. It played fine when I purchased it but started to crackle after I got it home. V1 or V2 seems "loose." Not sure I have time to chase it at the moment. k
 

Telekarster

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LLC and Tele: Thanks for the responses. In the meantime, I've been doing searches such as "Fender Excelsior R5." I've actually found a single post that describes these mods to a "T." It's likely the person who modded this very amp! (See https://www.thegearpage.net/board/i...-for-excelsior-amp-mods.1290707/post-19616692.) The mods are all just as you two describe: the tone pot (of which i was aware), the oscillator switch/jack, the preamp bypass input jack. * I'm going to have to dig into the amp at some point. The amp is pretty clean. It played fine when I purchased it but started to crackle after I got it home. V1 or V2 seems "loose." Not sure I have time to chase it at the moment. k

FWIW, and I posted this just the other day on another Excelsior thread, but I found an original 1959 Jensen alnico, as well as put some NOS tubes in her, and man she's super sweet now! Coupled with my tone pot mod, I'm very happy with her as is. I liked it beforehand, frankly, but these mods really opened her up ;)
 

Lowerleftcoast

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It's likely the person who modded this very amp!
I think this is that very amp as well.

Now I am pretty sure the red wire to the jack from R23 is not what I would like to see. If it is quiet as is, I would leave it, otherwise...

A simple fix would be to cut the wire at the resistor. Do not try to unsolder it. Heat damage to the PCB might occur. If you would like to keep the mod of cutting the first gain stage, you can attach the red wire to the volume pot as shown below. If you attach the red wire to the pot, try to position the wire against the chassis tucked up into the fold of the chassis. This would act as a partial shield, hopefully keeping it quieter.

Attaching the wire at the pot will enable the volume and tone pots to function when plugged into the jack.

Another alternative is to disable the mod by removing the red wire.

Inkedex2_LI.jpg
 

kraml_1066

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LLC: Thanks kindly for pointing out the potential problem with the signal chain. That is a long wire flying over there. Maybe it's close enough to metal when the top is on the chassis to cancel some noise. We have a giant gauge wire, too! It's barely tagged to the spot where he "soldered" it. I could probably safely remove it with a heat clip next to the board. He tagged the other spots with minimal solder (at least it's shiny). Some of the piggybacks feel a bit wiggly at the board. I'm thinking of upending it. Do you know of anyone who has done it? Any surprises? * Your rewiring suggestion reminds me of the Rickenbacker M11. It has wires from pot to pot tucked up under the chassis as you show here. I'm looking at this amp wondering if I can turn it into the M11 circuit, which is surprisingly sweet and clean if you know how to work the controls. But I am not a hands-on everyday tech; everything progresses slowly and with great thought and care. * MM and Tele have suggested NOS tubes and a vintage speaker. I have the tubes. The Ric still has the original RCA 6V6GTs. I don't know if I have any RCAs to throw in the Excelsior. The RCAs are best by far, but also a bit spendy. Because this is the Pro version, the speaker is not too bad--but it is ceramic. k
 

marshman

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I tube rolled a lot when I first got my Exy, and did find that the RCA 6V6GT sounded great…lots of headroom and punch, contrasted to a loosely-matched pair of NOS KenRads that got really dirty really fast (think Neil Young cranked 5E3), but in a cool way.

I’ve never checked, but I got the impression that the Eminence in the Pro model was much more efficient, and therefore much louder, which may not be what you’re after. It’s also heavier.
 

kraml_1066

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Fired it up tonite. Noise issue (crackling) was coming from tube in V1. The tabs and the socket itself are a little loose. Tightened ears. Socket is now tight but the tabs still wiggle. I've seen this before. V2 is tight as you please. Swapped preamp tubes. No more noise. Swapped back: sensitivity returns. Deoxit on V1 tube pins. Much better. The "troublesome" tube in V1 turns out to be labeled 7025. Some of the label, "Silvertone," remains on it in red ink. It's probably high gain and a tad microphonic; hence the sensitivity in that sub-par socket. Plus, who knows how many hours it has on it. The other preamp is labeled 12ax7 and has similar red ink markings. The 6V6s are "Made in China" (https://www.aliexpress.com/item/521634615.html).

Marshman, you are ceratinly right: this thing is LOUD. I like to play with the volume on the guitar nearly maxxed. The face of the amp is only a few inches from the wall where I am working on it. Standing behind it, I barely had to crack the vol knob to get plenty of volume for clean playing (w/a tele copy). It would be insanely loud dimed!
 

marshman

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I also tried a pair of matched vintage 6K6GTs and they were just as loud and also very easily overdriven, so they didn't help much in that regard. I still had the original stock speaker in it then, as well.
 

Telekarster

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Because this is the Pro version, the speaker is not too bad--but it is ceramic.

I liked the OEM ceramic fine but I came across a deal on an original Jensen and wanted to try it, and the diff was amazing to me, plus a bit lighter ;) The Emenence speaker is a quality speaker IMO and I've held onto it in case I want to use it somewhere else someday. BTW - I just noticed you're brand new here! Welcome! Also, if you hit the reply button or quote button, people will get notices that you replied to em, which is kinda helpful for those engaged in your conversation :)
 

kraml_1066

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I liked the OEM ceramic fine but I came across a deal on an original Jensen and wanted to try it, and the diff was amazing to me, plus a bit lighter ;) The Emenence speaker is a quality speaker IMO and I've held onto it in case I want to use it somewhere else someday. BTW - I just noticed you're brand new here! Welcome! Also, if you hit the reply button or quote button, people will get notices that you replied to em, which is kinda helpful for those engaged in your conversation :)
Thanks for the welcome TK! I'm certain that I had an I.D. under the old forum, but I don't remember what it was. Just created a new one (hadn't visited for quite some time.) I do remember that I've always had a good experience here: never been treated rudely and the greater percentage of folk here seem to be sane.
 

Telekarster

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Thanks for the welcome TK! I'm certain that I had an I.D. under the old forum, but I don't remember what it was. Just created a new one (hadn't visited for quite some time.) I do remember that I've always had a good experience here: never been treated rudely and the greater percentage of folk here seem to be sane.

Right on man! At the very least, we're all similarly screwball out here so... it's a win win either way LOL!!! :)
 




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