Post by thetragichero on Sept 23, 2018 20:22:48 GMT -5
I'm pretty sure it's the voice coil since there's no holes or tears and rasps when i push in the center. probably came this way. bummer. sounds killer distorted, so i guess i have a special application speaker that I'll have to build a cabinet for now to troll ebay some more...
Post by thetragichero on Oct 10, 2018 8:13:17 GMT -5
found a reconed Alnico speaker (hemp cone.... i feel like any puns would be lazy and /or not appropriate for a family - friendly forum) for less than 60 bucks shipped on eBay and pulled the trigger 25 watts power handling so it can get into speaker breakup territory. 96 dB sensitivity so not very efficient. maybe not as bright as the sunn speaker i had in there but sounds good. played last night after fitting it and then hooked it up to solid state pa to push some music through it to break it in just played it a bit and I'm liking this setup. cranked with a treble booster in front of it I can get some metalish tones from it (heavy bass cut on this booster but it was the only thing I could grab that had a battery in it) but sounds good clean as well (no buzz from broken speaker!) one interesting thing I've noticed is that the sag resistor bypass switch actually has a noticeable effect on the sound now, giving it a tighter, slightly louder feel I will still post schematic and maybe even clips... someday
edit: one other thing is that this Alnico magnet speaker is hella light compared to the ceramics I had in there. for a guy who used to play everywhere with two beads and two 4x12 cabinets, a lighter combo amp should help me age more gracefully
Post by thetragichero on Sept 17, 2019 23:41:36 GMT -5
seems like this was so long ago!
opened 'er up again. replaced the power transformer with the one that was in my 5e3 clone (this is the upgraded one, capable of running 6l6 output tubes) as i would like the option to run 6l6 or 6v6. i dig that both the ht and heater are center tapped. stock excelsior relies on two 100R resistors for an artificial center tap on the heaters, nothing for ht for the preamp section i did not like the tone control i had (stock bright/dark switch on either end of a pot), so I'm replacing with the tilt control from a supro thunderbolt (basically a big muff tone control). adding a 1nf bright cap to the volume pot
Post by thetragichero on Apr 10, 2020 22:30:13 GMT -5
I'm at it again....... tone pot was wired backwards and i think i tightened the speaker too much... sounds like 'cone cry'.... almost an out of tune octave up sound on the b string around the 14th fret. I'm gonna throw an organ pull rola usa speaker in the anyway so i can sell this hemp alnico guy I've had the 5e3 transformers in it for awhile running a pair of 6l6 (increased the wattage of the cathode resistor so it won't scorch). something like 400v on the plates and not much less on the screens. increased the power supply dropping resistor from 1k to 15k, in the process of changing the 470r screen resistors to 2k2. shooting for 360v plates 270v screens from 6l6 datasheet (quoted by someone on a forum and i looked it up last night sometime) with 250r cathode resistor (mine is right at 270r and that's close enough for me) need to change the other two supply node dropping resistors to get closer to the voltage readings on the excelsior schematic since the 6l6 draw more heater current than 6v6 and i have an unused 5v rectifier tap that i figure I'll run through a bridge rectifier for the preamp tubes I'd also like to try to fish up a negative feedback wire to the preamp tube board I'm also wondering about creating another baffle board if i can fit a 10 and two 8s in there..... yeah i know I'm a nut. but i have a 10" organ pull pyle driver that is probably my favorite speaker... i have a quad of the pyle driver 12s in my acoustic 105 cabinet anyway back to tweaking lol
Post by thetragichero on Apr 12, 2020 0:09:12 GMT -5
wayyyy too late to test but I've got the preamp tubes running off 12v dc heaters from the unused 5v filament tap, tone control wire the right way, negative feedback from the 8 ohm tap i stole from the 6g2 fender Princeton (which the excelsior is heavily based off of). also added some waterslide decals since i completely sanded off the control labels. at some point I'll spray some clear acrylic over to set em 33lb stock amp is now up to 45lbs with the addition of MUCH beefier transformers and the organ pull rola usa speaker i refuse to put knobs on it until I'm convinced I'm done tweaking
Post by thetragichero on Apr 13, 2020 22:27:44 GMT -5
something was wrong with my input wiring so i fixed that the RIGHT way now (68k grid stopper wired directly to first triode socket). removed the ferrite bead and 2k2 grid stopper from the pcb. quick test in the other room. LOUD and decently clean which is not what this amp was originally designed for but what I'm after. when it first starts i get a slight tremolo-like wiggle but then that goes away. the original bias tremolo circuit does not currently work which is to be expected since this is running 6l6 instead of 6v6 now. doing some research but it's not the top priority for this amp. supro/tilt tone control works as expected. tone pot pulls up for tone stack bypass i know I've done a lot to this thing but man if that negative feedback loop ain't exactly what I've always wanted: clean headroom!
besides the trem not working the only other issue was some rattling which these amps are known for. could be the grill cloth, could be screws, could be the handle. will investigate later
Post by thetragichero on Apr 14, 2020 13:25:10 GMT -5
put it through its paces this afternoon. I'm not got on the speaker for when it's cranked (a little dull) but i doubt I'll take it apart to put the square-backed Eminence i have in it. sounds GREAT cranked through my kustom 2x15 but then i haven't met anything that doesn't slay through those big ol jensens all in all it should work great for my intended purposes: when i need something bigger than the lab series l3 for worship or when i want a space-efficient (although heavy) grab-and-go amp
Post by thetragichero on Apr 17, 2020 21:58:11 GMT -5
put the square backed Eminence 15" in. 10s JUST won't fit depth wise (would run into the transformers) but this speaker is much brighter. i miffed when i redid the power rails so the triode and mosfet in the trem circuit weren't getting any juice! fixed it and tested plate resistors. settled on 120k (down from 220k) as that was the deepest wiggle. not as drastic as stock with 6v6s but still nice. I'm putting knobs on!
Post by thetragichero on Aug 24, 2020 3:34:22 GMT -5
I'M AT IT AGAIN
all of the mods was a pain in the rear on the stock fender pcb so i thought I'd make it easier on myself. that and besides not being a fan of bias wiggle tremolo it didn't like the 6l6s so much. to be honest i didn't realized i even liked tremolo until playing the sunn sceptre and vibro champ. thankfully mr sluckey over at the amp garage forum had what he calls the trem-o-nator that he's used in other fenders to good effect. single triode oscillator with a vactrol. have a few organ pull vactrols without model numbers listed so i tested the on (hundreds of ohms) vs off (out of range of my meter so above 40M) resistances and they seem to be what i needed
it's an embarrassment of riches with the extra space in the board! off board wiring is left for another day
You mean that it's becoming some sort of "gorier hatchet"?
No. Don't you know the story of Grandpa's ax?
As the story goes, Grandpa used to chop his own wood, and he used the same ax for over 60 years. Of course, over the years, he had replaced the ax handle 4 or 5 times, and he had replaced the ax blade 3 times. But it was the same ax he used for over 60 years!
Post by thetragichero on Aug 24, 2020 11:02:03 GMT -5
it's been a fun test mule. the epitome of "bought it because i liked the aesthetic." sound wise an amp that's only clean until 2 on the dual and then gets a raspy distortion isn't all that useful for me (found similar things with the 5e3 that i built and eventually stripped for parts. guess I'm not a 50s fender guy) this was the first amp i really got my hands dirty in. as much as i can read the neets courses and the valve wizard and forums, for a brain like mine it was invaluable to see the cause and effect of changing a plate resistor, cathode resistor, cathode bypass cap, etc it's surprising how massive 25w can sound when i run it through a 2x15
When you mentioned an axe it just jumped out at me that "thetragichero" contained the letters of "hatchet". "Gorier" was just the best I could do with what was left over, I guess I'm using it as a synonym (but not really) for gnarlier.
From this point forwards I hereby explicitly forfeit derailment responsibilities of this thread back to the officially sanctioned derailer.
Post by joshuaoforegon on Oct 28, 2020 12:54:31 GMT -5
Dear the tragic hero,
thank you so much for all of your posts! They are fantastic!
My name is Joshua and I have just recently purchased a fender excelsior which I am interested in modifying… Much the same as you have with yours.
Is there anyway I could ask you A few questions regarding these modifications?
I think I’ve got the tone switch -> knob modification down… What I am interested more in is your experience with switching out the transformer, and any other modifications I can do to make the amp sound higher gain...sorta like the Fender Ramparte hot channel ( or higher if possible!)
I must warn you this is the first amplifier I have ever considered modifying… Although I do have experience in Microphonr modifications, as far as amplifiers are concerned I’m a virgin.
i wasn't satisfied with a pot too go from the bright to dark settings (which is why i eventually replaced that while part with the supro/big muff style tone stack) but if you're looking for more preamp gain using a dpdt pot that shorts the in and out wires of the tone stack (essentially removing them from the circuit) as a "raw" switch would likely suit you pretty well the transformer change didn't necessarily provide more gain/distortion but switching the output transformer to a beefier one provided more headroom so that we're not getting as much compression from the output stage (the stock output transformer is woefully small for this amp, although i repurposed mine in a 20w fixed bias 2x6v6 power amp and it worked great). you'll want to look into a stand up type so that you don't have to cut into the chassis (i had to for the laydown power transformer i put in). be mindful of transformer dimensions as there's not a whole lot of space on that side of the chassis i changed the power transformer (and output tube cathode resistor) to allow 6l6 to be run on the power stage for that much more headroom. be mindful that the small stock power transformer does not have center tapped secondaries and uses a bridge rectifier for the ht voltage. the transformer i installed did have a center tapped transformer so i had to use full wave rectification instead (at first i forgot and had something like 720v b+) another useful mod was the "Paul C" mod on the cathodyne phase inverter. that and increasing the coupling caps from the phase inverter to the power section to 100nf helped a lot as you can read on the thread this has gone through many iterations to get to where it is. it's almost there, still have to tweak the new tremolo circuit
one thing to be mindful of with working on tube amps is mentioned in the sticky in this subforum: there are lethal voltages and one must be knowledgeable of draining filter caps