Would you like your Fender Excelsior to have the sound of NOS 6V6 tubes at an unbelievably low price? Well, read on.
The Fender Excelsior has been around for a few years now. It’s a very affordable tube amp that’s currently finding interest in the modding community because it’s affordable, and frankly, because it needs a few mods to get the most out of it.
The Excelsior is an odd duck that runs the plate voltage pretty low and uses cathode biasing with a 470 ohm cathode resistor. Normally a couple of 6V6 tubes will use something around 250 ohms so this value is just odd. Plate voltage is limited by the use of a couple of “sag” resistors in the high voltage line. So how to proceed? Do you remove the sag resistors to raise the plate voltage or change the bias resistors to a more typical value? With a soldering iron a little knowledge and a few parts you can do wonders. But what if you have no idea on how to do mods, or are rightfully afraid of sticking your hands inside a box that contains potentially lethal voltages. Here’s one you can do without opening the amp.
Back in the day, Fender designed a stand-alone reverb tank that was essentially a single ended amplifier much like a Champ. The power tube they used was a 6K6GT tube. The 6K6 is almost identical to a 6V6 but requires a lower plate voltage and a different resistor value for cathode biasing. The specs for this tube call for a 400 ohm bias resistor for a pair of output tubes and about 320 vdc max for the plate supply. This makes it an almost perfect match for a stock Fender Excelsior. All you have to do is remove the small cage that covers the power tubes and change the power tubes. 100% safe if you know how to unplug the amp first.
I was able to get a pair of tubes for around $20 and pop them in. Imagine the sound of vintage RCA or GE tubes for that kind of money. I’ve been running this set up for about a month without any issues, nothing but warm, sweet, tone. Change the preamp to a 12AY7 or 6072 tube and you are starting to get some serious tweed tone.
Give it a try. The 6K6 tube is still available and very affordable. The tube also works in reissue Fender reverb tanks to tame the gain and smooth the reverb. It’s fun and affordable.
I just ordered a couple 6k6’s to try out in my Excelsior. I’m looking for smooth overdrive that will mimic a female gospel singers voice or as close as I can emulate with my glass bottleneck slide. Do you recommend changing out the preamp tubes as well or would that be a bit more gritty and less smooth? I’m not sure what you mean by tweed-like I guess and thought I’d ask.
Cheers!
I bought an excelsior as well. I had to replace all the tubes even though it was brand new. It had one rattly power tube and one microphonic preamp tube.
With decent new tubes it sounds great. But mine has a dreadful cabinet resonance at higher volumes at around E flat on the a string.
At first I thought it was the tubes doing it, but it is clearly a bracing problem with the cabinet itself. Plugged into external 112 marshall it sounds great. Which leads to think about pulling it out and building a head. Which is sad, because the cab looks great, I think some of the ornate design is causing the vibrations. Any advice?
I had one of those from when they first came out. I think John’s recommendation for NOS 6K6’s would be a good one to try.
For me the biggest improvement came from swapping the stock speaker with an Eminence Legend 15″. That really improved the sound and volume. Enough improvement that later, Fender came out with the Excelsior Pro and that already had a Legend in it.
On mine I put a 1 X 3″ brace across the back, sounded great!
Forgot to add, the original speaker was made in China, the Eminence is made in USA. That might help to ID what you already have
I swapped some 6k6’s in my Excelsior and it sounds great! Still have to run it through its paces but I have a question before I get too wild with the volume knob.
I opened mine up and measured the power tube plate voltage at close to 400VDC, and the plate current at between 35 and 40mA depending on how loud I played. The data sheet for 6K6 that I googled reads that max plate voltage is 315VDC and Max plate current in push-pull is 61.
So, the plates voltage is roughly 27% above max rating and the plate current is around 65% of max rating.
Could you explain a little bit about how these figures are still safe for the amp? Does the high plate voltage get cancelled out by the low current in some way? Or is there something wrong with my numbers?
Thanks in advance!
I wondered what it would be like to put adapters on EL84 tubes and try that. I have a couple of the VHT tube adapters laying around. I am looking for earlier breakup and kind of a Fender rock sound. I play Contemporary Christian.. My current amp is the Blackstar Artist 15, which put 5881’s and a greenback in… The amp goes to the edge of distortion with British flavor. Not a high gain amp at all. Great for pedals… I don’t do high gain and would not buy many of the other BlackStar models.. What do you think about an EL84 running the Excelsior?
Is there a similar mod for the ramparte amp as well?
You may wish to check out the Fender® Forums for possible mods to the Ramparte. We do not have personal experience with it to say.
I have now successfully run ax7, ay7, au7, at7, av7 all in V1 and V2. Sometimes matched pairs, sometimes singles. Just changing out those gainy rotten Chinese tubes really cleaned up the tone. As fast as being too bright? Is there such a thing? Nope. You have a tone control on your guitar that actually works wonders on this amp. In the power stage I first replaced with JJ 6V6S, but they were very dirty and brittle sounding for my taste. Nice extended bottom end on them, but they break up alot with super distortions or bill Lawrence ceramic humbuckers. So ingot a set of vintage 50s RCA 6V6GT in there and wow what incredible tone they have! Way cleaner bottoms not as deep but I presume this means less breakup that happens much later around 12 o clock on the volume. For the most amazing sound yet, I popped in a way used set of 1967 Philips/mullard 6CA7(el34) xf2 Blackburn tubes. Now they dont work anymore in my 67 traynor yba1a bassmaster. Too much rattle and not high enough ratings. But undervolt the nearly dead tubes in the excelsior? And wow. It’s incredible. So for any of you who want to have a world if tones available for a variety of sounds and purposes. This is one amazing little amp. I can have one amp, swap preamp, or power tubes, and get funk, soul, country, pop, blues, Marshall, fender, box whatever sound I desire. And I love the raw simplicity of the design. Actually makes hearing the difference in tubes so much easier and allows you to dial in the overdrive you want without any pedals. On an interesting note, I’ve used microphonic 12ax7a tubes in V2 and found it generates a nice little reverb.