A Look Inside Fender’s Excelsior

This is a preliminary page for Fender’s Excelsior amp. The Excelsior will benefit from some mods and upgraded components.

New! I’m now offering the TO20 output transformer with leads and connectors set up for the Excelsior. The bass response is improved, it’s slightly louder, but the stock speaker is still a limiting factor. It sounds noticeably better with the Legend 1518 speaker. I provide a new Switchcraft output jack because the stock jack is cheap junk and it’s hard to desolder the stock transformer leads.

Second-generation Excelsior tone control is shipping. See this page, with sound samples:
Excelsior Tone Control

 

Click for larger image.

Here’s a look inside the Excelsior, the left (looking from the back of the amp) side of the power section. Apart from it’s “pawn shop” vibe, the Excelsior is modern inside. It includes an NTC thermistor to control inrush current and the full wave bridge diodes are individually bypassed by noise suppression capacitors.

The two large white sand-cast resistors are “sag” resistors, to simulate a tube rectifier. In addition to the main fuse, there’s a heater fuse and a soldered-in plate supply fuse on the output tubes.

Click for larger image.

This board feeds the output tubes. They’re cathode-biased, as you might have guessed from the 13 watt output rating. The sockets are ceramic. The output jack is rather inconveniently located behind the output transformer.

The flexible tube that connects the preamp chassis to the power chassis is standard, electrician-grade stuff. The tube is steel.

Click for larger image.

In the preamp chassis, the input voicing is done right on the jack board. There is no voicing on the guitar input, padding (reduced signal) on the mic input, and a fairly heavy treble cut on the accordion input. The mic input is somewhat like input 2 on a typical guitar amp: twice as much resistance, but unlike most Fender amps, it retains high impedance on the mic input. The accordion input is capacitor-coupled, which cuts signal strength and attenuates frequencies. I found it fairly useless for guitar.

The signal goes through the ferrite at the left to eliminate RF noise. Since there are only two amplification stages, they’re very high gain. Fender chose 220K plate resistors for the gain, plus a high value for the first stage’s cathode resistor. The result is kind of un-Fender-like.

The volume control and tone switch sit between the two stages. “Dark” is a heavy treble cut. Bass is the same at the Bright or Dark settings, but Bright activates a treble bypass cap that boosts highs. The contrast is too great between the two settings; this amp definitely needs a tone control.

Click for larger image.

The tremolo circuit is a conventional low-frequency oscillator that varies the grid bias on the output tubes. The tubes are cathode-biased, but there’s a combination of grid- and cathode-bias when the tremolo is active. The power transistor on the board is a MOSFET that drives the grids. The phase inverter is a conventional cathodyne circuit, much like that found in the Princeton Reverb or Tweed Deluxe. The signals go through individual, shielded wires to the grids of the 6V6s.

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The sockets are attached to the chassis and the 12AX7s are shielded. The amp is equipped with Chinese 3-mica tubes, which aren’t too bad.

Click for larger image.

The underside of the panel is straightforward. No circuit board-mounted components except the input jacks. Lots of room for mods!

Overall, the Excelsior is a loud amp and even with the two high-gain stages, it’s uncomfortably loud for home playing before you get crunchy distortion. It’s going to need some modification to allow distortion at more reasonable volume.

Modification Potential
The Excelsior has pretty strong mod potential.

I’ve already tested it with a one-knob tone control that uses the stock bright and dark settings as its upper and lower limits. I’ll be offering it as a kit. The control itself is the easy part. The harder part is a good-looking faceplate that covers the screw holes and slot. The slot also requires some filing to clear the shaft of the tone control.

I’ll also have a kit for a tremolo on/off footswitch.

The stock 12AX7s are not too bad for inexpensive Chinese tubes, but feel free to experiment. The stock 6V6s are just adequate. I prefer JJ 6V6s because the large plates improve bass response and they sound better overall. A better output transformer will help, but an upgraded speaker is a better investment, at least at first.

The stock speaker is not particularly efficient and has a characteristic tone that dominates the amp’s overall tone. An Eminence Legend 1518 is far more efficient–louder, with more consistent tone, better bass. It’s probably the most cost-effective 15-inch speaker you can find, too.

The Excelsior is clean at moderate volume. The best way to get overdrive tone at low levels is with a pedal. There may be other ways to get more gain out if it; I’ll post more as I experiment more.

Here’s a video of my Excelsior with a single-knob tone control, with and without the Eminence Legend 1518 speaker:

My take: The tone control really helps tone down the treble harshness. The Legend 1518 has classic tone, greatly improved lows, and a much more refined midrange. It’s also dramatically louder than the stock speaker.

291 Comments

  1. tjnugent says:

    Andrew, I had no problem with getting the bottom chassis back into the amp after installing the 1518. It does have a larger magnet and things were a tighter fit. If you still run into chassis rattle, you can do as I did, go buy some friction tape and go through the inside of the chassis and everywhere else you can think of. I even had to wrap the aluminum conduit that runs the wires from the top to the bottom and the tube cage. I also used loctite to secure all the chassis screws. I wanted to make sure I didn’t have to go back and do it again.

    My next mod is to make a back panel to protect the speaker and guts. This will be easy with a 6″ tall piece of birch and two 3/4″ rails, which can be had cheaply at Home Depot. I have not measured the width yet, but feel that this will be an easy and effective way to protect the back of the amp and allow it to be leaned back on an amp stand. When I make the measurements and complete the mod I will post the dimensions.

  2. kfwalton says:

    A few weeks ago I installed a tremolo footswitch control and a master switch in case u loose the footswitch looks very professional, also bypassed the sag resistors And added in a tone knob, really curious if you have any idea how to install an effects loop?

    • darrenr75 says:

      I get my Excelsior Pro delivered today, which I am over the moon about, but I can see that there are loads of possibilities with this amp.

      What I would really like are the following:

      A footswitch for the tremolo
      A way of changing the bright/dark switch to give me some kind of boost – and have this footswitchable(!)

      Are any of these possible?

      Cheers,
      Darren

      • bill says:

        A footswitch for the tremolo is possible. I haven’t taken the time to work it out. A boost is not likely. Both preamp sections are running at more or less maximum gain.

        Since you want the boost to be footswitchable, it would make more sense to use a pedal for boost. Whether you go for a clean boost or distortion, a pedal is a better choice than building it into the amp because you get to choose the level and the tone.

        • darrenr75 says:

          Thanks Bill.

          From reading all of the various forums, you are the most responsive technical support engineer on the planet!

          I take your point on the boost, I was just concerned pumping my Marshall Drivemaster through the Excelsior!

          With regards to the tremolo footswitch, I would definitely buy a kit off of you should you make one available – as I’m sure would many others!

          Cheers,
          Darren

  3. rduval says:

    Hi Bill:

    Haven;t seen anything lately on your site about the tone mod you said you were working on. Do you have one yet or in the works? If not, is it essentially the same as the “smooth Chocolate” mod from the UK?

    • bill says:

      My design is different from the Smooth Chocolate, which is the classic Fender single-knob control. The design I’m using is more independent of the volume control and it has a pull-up bypass for full raw tone. I tested a version last night that works well, but may be a little too dark/woofy at the bass end of the control. I’ll be testing another version with a smaller cap shortly.

      • rduval says:

        I’ll look forward to it! BTW, I have the Excelsior “Pro” with the Eminence (I assume its the 1518 in Fender label) and it’s got a pretty great sound. How do you think it would benefit from the TO 20 transformer?

        • bill says:

          The TO20 improves the tone across the board, but since there are other tone-limiting factors in the Excelsior, it’s not as big a hit as you get in a Blues Junior. But you can hear the difference. And yes, the Pro has a Legend 1518.

          • rduval says:

            Thanks Bill, think I’ll hold off on the TO20 then as I’m pretty happy with the sound. BTW, I took mine apart and weighed the components (Bathroom scale with me holding it and then without so these are pretty close). Pro Complete: 42 lbs, Speaker: 12, Electronics: 10, Cabinet: 20!!! Since I have a bad back I’m splitting it into Head and Cab. Will let you know how that works out.

          • bill says:

            I wish someone would make a light pine cab for the Excelsior. It would make a big difference.

  4. Bad Lou says:

    Bill,

    Re: TO20 output transformer for Excelsior.
    Thanks for the info. I’ll probably replace mine since it will help with improving tone.Anything to make it better I’m usually game for so….

    Just an FYI on what I’ve done to my Excelsior’s for you and your readers.

    I play 2 Excelsior’s in stereo (various FX) and have done some mod work already.
    The idea is to get a similar sound to my regular playing rig only a lot lower in volume, and a smaller combo package for smaller more intimate bars that usually don’t have a stage, or a tiny PA.
    I’m a huge fan of 15’s and I like a lot of headroom, so the Excelsior made sense to me….Anyhow….
    My normal recording/live set up is (2) Bassman amps, a 64′ and a 65′ (65′ is in a 15″ combo with a JBL and the 64′ is piggyback on top of a 2×12 Fender Vibroking Cabinet loaded with 2 California Webers. Big Huge Clean and LOUD.

    The Excelsior work I’ve done so far:
    The first thing I did was yank that speaker out.
    I had some old JBL 15″ 2220A’s stored away with original cones in near mint condition and figured these could be cool in the amp and yes they are very cool. (wow this amp weighs a ton now. The cabinet was heavy to begin with but now, wow)
    Whatever your 15″ speaker preference is, make sure you spend the money here and replace it with something of quality – In other words, don’t skimp here! After experimenting with my Excelsior amps and listening through various stages of my mods the speaker had the largest impact by far.
    Next I removed the cheap tin foil shielding they use and used a proper thin piece of sheet metal and the difference from quite a bit of noise to almost nothing was HUGE. I would highly recommend that this be done. I play Les Paul Standards with Lollar P-90’s and another with Lollartrons (Jason Lollars take on the Filtertron) with Bigsby’s and both guitars are as quiet as a mouse now. I can’t say how much by doing this it cuts out all the bad hum these amps have, it’s just not properly shielded at the factory.
    The next thing I did was change out all of the tubes. I usually have a stack of NOS and newer tubes laying around so I just used those and any newer tubes that I think worked or that was appropriate. Currently I installed some RCA black bottle 6V6’s in the power section, a GE 12AX7 in the tremolo, and an EH 12AY7 in the driver. Since my needs are to get ‘clean tones’ the 12AY7 I thought was a bit nicer/better than a 12AT7 which is OK too just breaks up a little more is all. A 12AX7 broke up way too much for my ‘current’ style of playing. (If I want overdrive I use a pedal) All of these tubes sound so much better than the stock tubes, but hey if your budget is nil or small, then stay with the stock tubes and use the money for the speaker!!
    After that I swapped out the bright/dark switch to a tone pot to be able to have more control over finding a ‘sweet spot’, then I added a foot-switch jack for the tremolo. I’m a tremolo nut and I like the tremolo on this amp because it’s different from my pedals, even though in my FX chain I use a Fulltone Supatrem and a Strymon Flint that has both Reverb and tremolo I also wanted to utilize the amps tremolo as well so yeah I have a lot of tremolo choices going on now….I made a custom switch that can turn both of the amps tremolo’s on at the same time, or one at a time. I also replaced the speaker cable with a with some 16gauge speaker wire and used a Switchcraft 1/4″ plug from extra parts laying around. Doing that seemed to make the low end a bit more pronounce. I always make my own speaker cables that way I can make them as long or short as I need them. I also replaced the screws that hold the bottom chassis down with some 1″ self tapping hex screws that have a metal/rubber washer that are a bit longer to hold better and the rubber side helps it from coming loose and dampens as well, plus they are a heck of a lot easier to remove when you need to (also helps tapping into the sheet metal shielding on the top flanges) So now this amp is verging on something pretty cool, and quite honestly it wasn’t too much work that I wasn’t pulling my hair out.
    Next up is to replace the output transformer on these amps to help improve tone but I have to say as is now, they are pretty damn cool!
    Rock on.

    • rduval says:

      I’m surprised that the sheet metal vs foil would really make a difference. I’d think that electrically they would be the same (Bill please correct me if I’m wrong on this). If they are, perhaps it was just better contact with the chassis? If not, I’ll certainly give it a try.

      • bill says:

        A thicker panel does shield better against some kinds of interference. They’re all pretty much the same for radio interference as long as you have a good ground. If you switch from aluminum to steel, you get better protection against magnetic fields. Even thicker aluminum is better for magnetic interference because you get eddy currents in the aluminum that weaken the field.

      • Bad Lou says:

        I never insinuated that the sheet-metal was better than aluminum foil. I was stating that the stuff they use in this amp is junk – it’s thinner than paper and a lot of it was ripped up. Both of my Excelsior amps were pretty noisy. I only used the sheet-metal because I had a roll of it laying around, the idea to use what I already had vs. buying stuff that I don’t need. (I just cut it with tin snips, actually some heavy duty scissors would’ve worked too) We just built a brand new house with all new electrical so I know we have a great ground here, in fact the code calls for (2) 8′ spikes to be put into the ground, even the electrician said they changed that code here somewhat recently, anyhow….. My 69′ and 70′ Marshall’s and Bassman’s sure weren’t noisy, but that depends on what your your wife and kids consider noise I suppose :)
        I read on another site,/amp tech that he would use wire mesh because its easy to cut and mold around things as need be. Actually, both of my Bassman’s have steel wire mesh on the top for shielding. My Marshall’s have a thin piece of aluminum metal. On another 73′ small box 50 watt Marshall I have it had no shielding at all, (removed?) and I used that copper snail tape and lined the bottom with 2 layers of that, and well it worked! Again left over stuff from unrelated amp projects. I wouldn’t even know where to find thick sheets of aluminum as thick as the steel I used, but I suppose if I didn’t have anything I would’ve looked around the internet and bought some, but like Bill says “It’s pretty much the same” The idea was to use what I already had and it did the trick so it’s one of those things where if it works, it works!?

    • darrenr75 says:

      Hi Bad Lou,

      How did you make a footswitch for the tremolo?

      Cheers
      Darren

      • darrenr75 says:

        Hi Bad Lou

        Can you please let me know how to do th tremolo footswitch? Pretty please!

        Cheers,
        Darren

        • Bad Lou says:

          Sorry, I haven’t looked at this or logged in for a while now. I found this and tried it out and it worked perfectly. It was stupid simple.

          http://judyboxamp.blogspot.com/2012/12/installing-vibrato-footpedal-on-fender.html

          I used a Marshall Jack – Mono Cliff input/speaker jack. Cost is maybe a couple bucks. Google it, or check ebay for best prices. I bought white ones for something different. I installed mine on the far right side of the back panel (when chassis is installed – looking at the back, in the far right lower corner) and used a right angle plug for the switch. There seems to be plenty of room on the inside of the chassis so where it goes is up to you based on accessibility really. Have fun and Good luck!

          See my comment below. – Bill

          • bill says:

            This mod transfers control of the tremolo from the knob switch to a footswitch. No footswitch, no tremolo. As Bad Lou points out, there is a voltage on the jack and you must use an insulated jack and an insulated/isolated footswitch, not one where a metal jack is grounded to a metal footswitch body. Most footswitches are not made that way.

            Also, I would recommend using rubber-gripped guitar cord for connecting the footswitch to the jack, because the metal sleeves of a standard 1/4 inch plug will have the voltage on it. The voltage is fairly low; it’s not dangerous to you. But grounding it will melt stuff in your Excelsior.

            Older Fender tremolo designs just grounded out the oscillator. There may be a way to do that here; I’m looking into it.

  5. Bad Lou says:

    Another good (or cool) replacement would be the jewel on this amp. It looks like a traditional Fender jewel only It’s plastic junk and a real Fender one would look great and seems like it would be easy to do? It’s more or less the same should just be drop in, solder and go!?

  6. fifje says:

    Hi Bill,
    Thanks for all the info on this amp! You have a great site here!
    I used to play a ’63 Vibroverb RI with the best bias tremolo I have ever heard. It sounded great when cranked but way too loud. When looking for an amp with bias tremolo and a little less output I found the Excelsior.
    I bought the Pro version, switched out tubes, did the tone pot mod and plan on bypassing the sag resistors soon.
    I still feel there’s more hidden potential in this amp and I’ve read that it’s apparently not much to change the preamp to 6G3 specs. Can you or anyone on here recommend this?
    I would also love to have the tremolo speed a little faster. Is there an easy way to do this with changing a resistor?
    Best
    Toni

    • bill says:

      The speed pot is bounded by two 100K resistors, R21 and R37. If you make these resistors smaller, it will increase the maximum tremolo speed without affecting the minimum speed. You can do an easy top-of-board mod by soldering another 100K resistor across the leads of R21 and R37. Two 100K resistors in parallel gives you 50K, and lets the circuit oscillate faster.

      The maximum speed, according to my meter, goes from 5.3Hz to 6.4Hz. That doesn’t sound like a lot, but it’s a 20 percent increase. Using 82K resistors (effectively 45K) only gets you to 6.5Hz. I have 82K resistors soldered into mine, and I’ll probably leave it that way.

      Note that if you go too low or try to run without resistors, the tremolo circuit won’t oscillate. It’s fussy.

      Excelsior tremolo mod

      • fifje says:

        Thanks so much, Bill. That’s exactly the info I was hoping for. I only want it to be a little bit faster, so 20 percent will be more than enough for me and this looks like an easy mod. Thanks for the picture!

  7. ptoscano says:

    Bill, I’m a harp player who owns one of these amps. The first thing I did was to install a tone circuit with a cap and tone control (500k) that tie into the volume control. I removed the switch, R8, R9 and R29 from the PC board. It was designed by an amp guy in the UK and he calls it “Dark Chocolate”. The amp became close to amazing after that, so I’m thinking speaker. I was wondering if the Eminence Legend 1518 would reap me some major benefit over the stock, or should I go with a Jensen Vintage C15K8. I have a Jensen Vintage C12K8 in another harp amp that sounds pretty darn good.

    Also, I’m trying to figure what other offerings you have for the Excelsior that might help make this thing a monster. Thanks, Paul. toscano.paul@gmail.com

    • bill says:

      I’m about to offer a tone control of my own design; you can hear it on the video on the tone control page nested under this one. You can also upgrade the output transformer for better tone quality, but the ratty tone of the Excelsior doesn’t get as much benefit from it as many other amps do. The Legend 1518 is a huge improvement over the stock speaker. I haven’t heard the Jensen, so I can’t compare, but there aren’t many Jensen speakers that I like.

      • ptoscano says:

        Bill,

        Thank you for your reply and insight. I did watch your video, and I’d be interested in the output transformer modification. I believe that is something you do, or plan to offer. I’ll check it out. Thanks again, Paul

  8. tubeholic says:

    Hi Bill, I have a question for you. I’ve been experimenting with master volumes on the Excelsior. I have tried the cross-line Post-phase inverter Master Volume, but found it to be an absolute raspy fizzy mess of a Master Volume. So I tried the bootstraped Cathodyne Master Volume, which is great. It won’t allow you to push the PI, but it is very transparent and now I can have a bluesy, bold and punchy tone at minimum settings. Love it.

    The one thing I’m not crazy about is this: As I turn the Master Volume Control to minimum, I get an increasingly louder buzz (seems like bad grounding). It’s not intolerable, but it is annoying. Do you have any suggestions as to what might be causing this?

    Thanks!

    • bill says:

      If you can post a schematic, I’ll take a look at it. Maybe I can try it in my amp to see how it works.

        • bill says:

          Thanks. That looks pretty straightforward. Anyone else looking at this clip should note that C1 and C3 have been increased from the stock .01uF to .1uF, which is a more typical value for driving 6V6s. I’ve done this on my Excelsior, however, and the difference is barely noticeable.

          Your schematic gives me the idea that it would be fairly simple to do a post-PI master on the Excelsior, too, either a single-pot cross-line master or a dual-pot. Since the concertina phase inverter isn’t a gain stage, though, I don’t know if it would make much difference in tone.

          • tubeholic says:

            Yeah, that’s exactly what I tried first, the cross-line (aka Matchless type) MV. But it sounded terrible. As for C1 and C3, I had to bring those up as they form a hi-pass filter in conjunction with the potentiometer to some sort of virtual ground, which made the sound thinner and thinner as I lowered the volume. 0.1uF caps took care of this issue.

            Then I tried that pre-PI MV, replacing the grid leak resistor with the 1M pot as per the schematic. It sounds really cool although it kind of tames down the whole amp in lower volume meaning it doesn’t really get as dirty as it should IMO. Anyway, as I was in there, amp guts out of the chassis, I added that big 1M grid stopper to the PI.

            Which brings me to this point. Today, I gave the the cross-line MV another shot. And this time, I guess it sounded ok. Not brilliant, but ok! I really wish I could clear some of the harshness, but this is actually usable. Guess having that big Grid stopper really makes a huge difference.

      • tubeholic says:

        BTW, if you happen to try it out, please let me know what you think.

  9. darrenr75 says:

    Well my Excelsior Pro finally arrived today, one of the Surf Green ones. Very well put together amp, apart from some of the tolex (is that right?) joins, but I can sort those easily.

    I get quite a rattle from the back, but after powering down I can see that one of the pre amp tubes housing that screws into the bottom of the top part of the amp has a bit of movement to it.

    So onto the sound!

    I’ve got an Epiphone DOT 335 with Seymour Duncan P Rails, so I can switch to single coil or P90, or humbuck them both in and out of phase. While plugged into the guitar input, and volume on half way, this is like an out of control wild horse! I can get very authentic Hendrix tones from the single coils, and 70’s sounding Deep Purple/Black Sabbath stuff from the humbuckers. But it’s VERY responsive to the guitar which is great.

    I’ve found that the best sound for this guitar is plugged into the mic input.

    And I have previously read about putting the dark/bright switch in the middle to get a mix between the 2 – and this actually works!!!!! Will I do any damage doing this?

    I’ll try my Les Paul tomorrow, and a Strat soon, which I’m sure will sound a little less aggressive!

    One final question – if you run a pitch lead from/to two of the inputs and plug the guitar into the other, does this change the sound? I’ve read a few times that the bass boosted or similar.

    Cheers
    Darren

    • bill says:

      As it says on the Excelsior page,

      In the preamp chassis, the input voicing is done right on the jack board. There is no voicing on the guitar input, padding (reduced signal) on the mic input, and a fairly heavy treble cut on the accordion input. The mic input is somewhat like input 2 on a typical guitar amp: twice as much resistance, but unlike most Fender amps, it retains high impedance on the mic input. The accordion input is capacitor-coupled, which cuts signal strength and attenuates frequencies. I found it fairly useless for guitar.

      Jumpering two of the inputs only changes the sound in your head, not in the real world. You might hear some treble roll-off, which some people might mistake for bass boost.

      Putting the tone switch between bright and dark can’t hurt anything.

      • darrenr75 says:

        Hi Bill,

        When I use the mic input, and jumper a lead between guitar/accordion it definitely adds quite a lot of bass! Very noticeably.

        Darren

        • bill says:

          No, that’s not what’s happening. When you have a guitar plugged into the mic input and put any connector into the guitar input, it switches the connection back to the guitar input. It doesn’t matter if the plug you put into the guitar is connected to anything or not. In other words, the sound with the guitar plugged into mic and a gtr/accordion jumper is exactly the same as if you plugged into guitar and had no jumpers. And as I’m sure you’ve discovered, there is no change when you jumper mic and accordion.

  10. darrenr75 says:

    Hi everyone,

    Does anyone know how to install a footswitch for the tremolo for this amp?

    It’s a beautiful sound, but I want the option without having to go back and forth to the amp!

    Cheers,
    Darren

  11. darrenr75 says:

    Hi Bill,

    My Excelsior today is not functioning very well. Yesterday it was absolutely fine, cranked and quiet.

    When I play the amp on the Bright setting it really crackles like when you have a bad connection on a guitar jack lead but really LOUD (it isn’t the lead as I’ve tried another and the same thing happens) and it doesn’t really do it on the Dark setting.

    Any ideas? Or is this the push for me to wire up a pot for better tone control?

    Cheers in advance
    Darren

    • bill says:

      If it crackles when you play hard, I’d say you really do have a bad connection or a bad tube. Make sure the tubes are fully seated in their sockets. A bad solder joint can cause that kind of crackling, too, but I’d suspect the tubes first.

      Another possibility is that the tone switch is worn or messed up. Does it clean up if you press the switch firmly into the bright position, or if you press down lightly while it’s in the bright position?

      • darrenr75 says:

        It’s one of the pre amp tubes. Off to the shop I go I go…

        • darrenr75 says:

          I’ve popped a jj 5751 into v1, with the working Chinese one in v2. Very occasionally I’m still getting a cracking sound. Aaaaaaargghhh.

          • darrenr75 says:

            And today it’s working fine……

            Quick question, do tube dampers really work?

          • bill says:

            Tube dampers sort of work. Nothing can stop a microphonic tube from getting worse, until it’s unusable, but a couple of silicone rings will slow down the process and perhaps protect the tubes a little longer.

          • darrenr75 says:

            Thanks.

            By the way I’ve put the JJ 5751 in v1 with the stock in v2, and it hasn’t really given any more clean headroom and to be honest hasn’t really changed the sound!

            Would changing the power amp tubes to something more decent make THAT much of a difference?

            Darren

          • bill says:

            No. Tubes do very little to change an amp’s tone. Maybe a little brighter, a little fuller, a little more mellow depending on the tube. But nothing dramatic. The electronics determine the tone.

          • darrenr75 says:

            After I complained that the stock tube broke, my dealer got Fender to send me a new groove tubes 12ax7r which apparently is a little less gainy than the 12ax7.

            It definitely does sound a little more defined.

            Now onto making a footswitch for the tremolo.

            Tanks for your help.

  12. cliffman says:

    Bill,

    Regarding your post:

    September 5, 2013 at 10:38 pm
    I wish someone would make a light pine cab for the Excelsior. It would make a big difference.

    I have found a fellow north of Boston Ma, who is making clear pine cabs for Bjrs. He has several types to choose from. Std size and oversize. He will baffle for singles, doubles, etc. Also for any speaker diameters. His pricing is reasonable and he told me he is stocking cabs so no waiting.

    When asked about possibly making cabs for the Excelsior, he was positive and had two ideas. First, use one of his oversize std cabs to accommodate the 15″ speaker…. OR…. he is willing to fab an actual E type cab.

    His name is Carl and his website is Carl’s Custom Guitars.

    Clifton

    • bill says:

      I have one of Carl’s Blues Junior cabs and have used his cabs for customers’ amps, too. He does nice work and has reasonable prices. I think the E-style cab would make the most sense. Making the cab a little deeper would help the low end, too.

  13. gdweinstein says:

    I just bought the Legend Eminence 1518 speaker for this amp…. It does not have an indication as to which connection is positive and negative for the wiring, and I soldered the 2 wires to each connection anyway without knowing if it matters. It sounds fine and seems to not be an issue. Just would like to confirm that this is ok?

    • bill says:

      The polarity doesn’t matter on a one-speaker amp. But I don’t understand how you soldered two wires to each connection. Or why you soldered them, instead of using the push-on connectors.

      • gdweinstein says:

        Ok you answered my question. “polarity does not matter on a one speaker amp.” … I meant to say that I connected one wire to one connection on the speaker, and the other wire to the other connection. I had to desolder the stock speaker wires so I assumed that soldering the new speaker was acceptable..

        • bill says:

          Interesting. My Excelsior has push-on connectors for the speaker. If you had solder instead of quick connects, then you did the only thing available to you, other than buying quick connects :).

  14. gdweinstein says:

    also, thank you for the tone mod. Love how I can pull up on it and bypass the tone. Makes for one loud, raw amp. 2 thumbs up.

  15. chrism says:

    I’m very happy with my Excelsior; it’s cheap, loud, characterful and moddable – I’ve already added a tremolo footswitch socket and re-cabbed it.

    I’d very much like to try the tone mod (though I’m in the UK and the postage cost is a bit terrifying – does a pot and a few other bits have to cost $24 to send, Bill? You should change your courier).

    However, the biggest difference I’ve found is to swap the cab for a proper pine one. I tracked down a cabinet-builder who mostly makes tweed-style cabs, sent him the measurements and he built me a bespoke Excelsior cabinet. It looks great, sounds resonant and much livelier, and doesn’t weigh the same as an Ikea wardrobe. And it isn’t dog-poo brown like the original either; I left mine in natural pine for extra resonance. Though tweed would be cool if you’re into that retro thing. Have a look for doublenickels_55 on eBay if you’re in Britain or the EU. No, I don’t know him but he did a nice job for me.

    Other cabinet builders would no doubt do a decent job, but whoever makes it, I’d give a cab-swap a go. Makes a huge improvement. And my back is thanking me too.

    • bill says:

      I used to send kits to Europe via first class mail, but many customers wanted tracking, so I switched to Priority Mail. Perhaps when the tremolo intensity mod and footswitch kits are ready (soon) you can order all and the cost of the postage will at least be less than the cost of the mods.

  16. gdweinstein says:

    anyone know of a road case that fits this bad boy?

  17. shawn says:

    Bill,

    Thank you for all the incredible info at your site.

    I bought an Excelsior and trying to figure if it is worth keeping. From what I read, the speaker replacement is most important. The tone mod would be second. Will that make this amp gig ready? The thing I am wondering about also is the transformer. How necessary and when.
    I have a Peavey classic 30 that I use primality. The excelsior would be for home use and serve as a back up. At 13 watts, it is slightly underpowered.

    BTW, please consider digging into the Peavey Classic! There are lots of them out there. Sound pretty good but with your help, they could be great!

    Thanks again Bill. Great site and info!!

    • bill says:

      Yes, the speaker makes the biggest difference, then the tone control, then the output transformer.

      Peaveys, with their folded circuit boards, are an absolute pain to work on. I don’t knowingly subject myself to that kind of suffering.

  18. shawn says:

    Any tips on legend spkr install? I read that some folks had trouble getting the top and bottom amp components to fit after. Also does the orientation of the speaker terminals matter?

    Thanks

    • bill says:

      Everything fit fine in mine. I haven’t heard any stories of things not fitting. The orientation of the speaker terminals doesn’t matter.

  19. shawn says:

    Speaker went in just fine. The bottom section (power amp) was a little weird getting in and out. Any tips appreciated for the future, as I did tear up the foil just a bit.

    The Legend 1518 sounds wonderful in there! Big improvement as everyone has stated. The amp sound very good until after about 2 or 3:00. When it’s cranked it sounds really flabby in the low end; not pleasing at all. Can I assume that it’s the tubes? I am using the stock tubes still.

    What a great little find this is.

    • bill says:

      It’s more likely that an upgraded output transformer will give you a firmer low end, although the bigger plates in the JJ 6V6S might help.

      A stiffened power supply might help, too. I haven’t tested the effects yet on the Excelsior. I also think that a degree of low-end distortion is part of the price you pay with a cathode-biased amp. When you start to draw serious current, the cathode resistor causes a voltage drop and limits the current, which can cause distortion. I haven’t put a scope on the Excelsior to test this; it’s just a theory.

  20. shawn says:

    Bill – Not sure I like the sag resisters. Are they a big deal to take out? Do they only kick in when you push the amp? Thank you!!

    • bill says:

      You just have to get to the bottom of the board and desolder them and replace them with insulated wire. Or bridge them with wire from lead to lead.

      I’ve tried not to do any mods to the Excelsior that require component removal or major disassembly. Keep it simple.

      And yes, the sag resistors have the most effect when you dig in on a note or chord. The resistors limit the current, so the voltage drops and the amp distorts a little more easily. When the note begins to fade or you play more softly, the power supply catches up with the demand and it cleans up.

  21. shawn says:

    Hi Bill,

    I am going to go ahead and do the tone mod and the transformer mod. Please excuse my ignorance as I am new to modding. Should I do it all at once while amp is open and apart, or should I do one at a time? This is my main question.

    I guess I will replace the tubes last. These sound ok – for now. Maybe just the 6V6? You mentioned that they were a bigger improvement than the preamp tubes were.

    This has been a fun experiment. Thanks for all you do!

    • bill says:

      Since one mod is in the upper chassis and one is in the lower, you can do them one at a time and hear how the tone changes and improves. The JJ 6V6s will sound warmer and fuller, too.

  22. copperheadroads says:

    I got the Legend 15″ to go in my brown excelsior over the holidays & before I get at it ,It might be handy to know whats involved ……………Do I have to remove top & bottom chasis ? or can I get away with removing the top ???????? & yes I am schooled in modding gear just trying to minimize the time taken to do this mod & to spend more time with my family
    any info/experience will be greatly aappreciated ……………Thanks ……….Copper

    • bill says:

      If you take a peek back there, you’ll see that the lower chassis blocks access to the two lower speaker screws, so it has to come out. After you remove the chassis screws, you may have to lift and wiggle it a bit to get it out, but it’s not difficult.

  23. shawn says:

    Got the tone mod stuff and the transformer. Just hoping for some quiet time to get it all done.

    As far as the soldering under the orange cap on the tone control, can that be done before installing it ans screwing it in? Like the other guy, I don’t have the steadiest of hands, but enjoy projects like this.

    Which will be more difficult, the tone mod or the transformer mod? Which will be more time consuming? Trying to figure which one I should do first? Thanks!!

    • bill says:

      I think you should attach the tone control to the chassis before soldering, so you only have the wire and the soldering iron moving. Stick the wire in the terminal, bend it with a jeweler’s screwdriver or small needlenose pliers so it doesn’t come out, then solder when it’s in place and your soldering iron won’t knock it out of the hole.

      The transformer is more time-consuming since you have to loosen more stuff and replace it.

      • shawn says:

        Thanks Bill.

        Do you know what size spade terminal Eminence Legend takes? My original speaker connection is soldered and I was thinking that since I am taking everything apart, maybe I should reconnect the speaker with female spade terminals as opposed to solder. The problem is, I am not sure what size is typical. I remember reading that your Excelsior had slip on terminals, whereas many of us have it hard soldered.

  24. shawn says:

    I installed the transformer and the new JJ tubes. Had a real scare. Put it all back together and ——-NO SOUND!! I was freaked thinking “nice way for me to ruin a new amp”. Turned it around and duh, I forgot to plug in the speaker cable.

    Next week I should have a bit more time and a pencil soldering iron. I will try the tone mod then.

    Thank you Bill. This amp is really shaping up.

  25. andregodoycoelho says:

    Hi guys!

    I swapped the 12ax7 tubes for two 5751. Much better control overall, specially with the harmonica!

    But I felt that the tremolo depth decreased a bit. Is there a way to make it stronger or is it already maxxed out? I don´t feel that I need the depth mod, as I like the preset with the 12ax7 very much.

    Thanks very much in advance!
    André

  26. andregodoycoelho says:

    Tks very much Bill! Will swap back then.

    So, I am having this idea to help me with the harmonica. The TMB tonestack helps quite a bit with feedback issues because of the mid scoop.

    Though not a good idea for the guitar, since it will compromise a lot of signal, it should be more than fine with the very high output of bullet type microphones.

    I though of using a DPDT to make two different paths by lifting C15 (the 0.047uf coupling cap side connected to the first tube´s plate) and R23 (2k2´s side connected to C2).

    In one position, I would choose the original path, on the other, I´d remove the original path and substitute with the tonestack. In order to avoid drilling too many holes on the chassis, I am thinking of building the tonestack as an external unit, and use standard guitar cables for the connection.

    I don´t think it will hurt anything, but switching on the fly may cause a loud pop. Should I take specific cautions? (I am concerned about the high voltage noted on the schematic on the tube 1 plate which is also connected to C15).

    Thanks once again guys!
    André

    • andregodoycoelho says:

      from reading Bad Lou´s and yours comment, I figure I should use all (4) insulated jacks…am I right?

    • andregodoycoelho says:

      Hum, maybe I´ll go for the rocket command panel look on the excelsior.

      The dpdt switch can take up to 220vac – 1,5a or 110vac – 3a.

      From the schematic, around c15 (which will be connected to the switch) I see 212vac – 0,18a.

      Can someone please confirm wheter am I correct to assume that there won´t be problems using this switch?

      Tks!

      • bill says:

        What do you want to do with the DPDT?

        • andregodoycoelho says:

          I´d like to have two different paths for the tone section, one will go through the tonestack as is, and the other through a TMB type tonestack.

          So, basically I´d have the portion between just before c15 and R23 on a switch. My concern is that C15 is directly connected to the first tube´s plate, and the voltage noted on the schematic is 212vac and 185mA.

          • bill says:

            Sorry, can’t even begin to think about that. It sounds like a mess to me. Good luck with it.

          • andregodoycoelho says:

            Hi Bill, thanks for taking the time! It is messy indeed, but could lead to a Nice result. Will let you know.

            Anyway, I got most of it figured out actually, but just to simplify my question, would anyone know if i could use a switch (as spec d above) to select different values for just c15, considering the voltage and current around it? If that is ok, the rest should work.

  27. fifje says:

    Hi Bill,
    When trying to add another resistor on 21 and 37 I was experiencing with either a 100k or a 82 k in parallel.
    Unfortunately I was stupid enough to touch Q1 with one end of a resistor.
    Now the tremolo depht is gone. I can still hear the speed control work, though.
    Guess I blew the mosfet transistor…
    Any recommendation on what I should put in there?
    Thanks
    Toni

  28. fifje says:

    Problem solved. I already put a new mosfet in there. It’s an IRF 820.
    It was no fun to unscrew the board, though…haha.
    I have to say I like the tone control a little better with R8 clipped out.
    Bypassing the sag resistors was a good thing, too.
    Thanks again!
    Toni

  29. Billy says:

    Installed the new T020 output transformer, the new tone circuit, and installed new Legend 1518 speaker. Also installed a matched pair of RCA 6v6 and JanPhillips 12AX7a tubes. I like playing tele’s – They all get crunchy very easily with the volume at five if I am aggressive with my picking and when picked more softly, the amp gets so clean. What a little gem of an amp! Bill your mods were easy and straightforward to install. The made a dramatic improvement in the tone of the amp. I look forward to your Tremolo mod- love to have an on/off switch with that feature.

    Thanks!