Tube Amp Help

I just bought a Fender Super Pro (1993) and it sounds extremely harsh and heavy on the treble even when I roll the treble and mids back. But when I switch to the neck pickup on my guitar it's too muddy. I know it isn't the guitar because it's worked perfectly on other amps. Should I replace the tubes and if so what with? I want a good standard Fender clean with crunchy overdrive. But instead I'm getting too bright cleans and way too sharp overdrive. Should I also be concerned that the amp starts to break up when the volume is at 3? It's a 4x10 in case that would help.

thats the amp, like it or lump it... try replacing V1 with a bassy/middy tube maybe tung sol RI 12ax7, but the difference will be minimal.... try different speakers, something with a cloth surround bass cone? or a hemp cone? not a good era for Fender amps

I figured I'd replace the tubes in it and try running it through different speakers. It came with Jensen blue speakers in it. I was thinking maybe some Mesa tubes because it takes 4 12ax7's and 2 12at7's. I'll try all I can with it and if it doesn't work I'll just sell.

mesa doesn't make tubes, they just test and rebrand whatever they get cheapest and upcharge you... if you want tested, rebranded tubes go with groovetubes but I recommend just buying from a tube dealer like tubestore or tube depot.... try the New Sensor made Tung Sol 12ax7 reissue, its unharsh and has nice distortion and compression, tends to overload early and nicely in most amps, lots of bass and treble, but good treble... JJ 12ax7s tend to be on the dark side and sound 'cleaner', they make a lot of varieties but they are all a good choice to tame a bright amp and the higher internal headroom tends to tame some harsh.

You can go further down the rabbit hole if you want, but maybe start with a handful of Tung Sols and a handful of JJs and experiment with different positions in the preamp

the 12at7 tubes are probably the phase inverter and the reverb, it might have a tube chart that could tell you.... you can use whatever in the verb driver/recovery circuit but you shouldn't swap from an AT7, it'll work, but not ideally, anyway the tube in there is fine I'm sure as its only really being used in the reverb signal (some will make bones about reverb drivers, but hey, you have bigger problems right now).... but in the PI a 2ax7 will up gain and change the frequency response a little, but not in a predictable way. Try it.... no one makes a good sounding current production AT7, I would look at NOS from a tube dealer, all the old ones make a good phase inverter

hmmmm

1st off define great fender clean? big tweed? little blackface? big blackface? maybe a silverface? some of the sf oddballs sound quite good at clean you know! the bandmaster reverb springs to mind

are the cleans harshly bright with no effects in line?? when you're getting harsh drive is it from your pedals or the amp's built in gain (it has a gain channel right? I am pretty sure these amps have a gain channel, but its not well designed and you will never get a good sound from it). it might have a permanently installed bright cap on the input or somewhere in the drive section (maybe on the master or gain knob) that you could clip out, though it will make it duller at low volume settings and all around bassier... it may also be biased too hot or too cold, you would probably want to go to your local tech for a power tube swap and rebias (if its a 6L6 amp which I think it is, try the Groovetubes 6L6GE, the only tube GT actually MAKES in old GE plant here in the USA), I am not sure if the amp should be breaking up on the clean channel at 3, its not uncommon to encounter this in old fenders that have drifted a little, but generally they're clean up to 5 or higher so you might not be biased properly or you might just have dead power tubes, either way a trip to the tech will diagnose that and it couldn't hurt the amp to be serviced ... hey, do the power tubes look like a matched set? if they are the same brand do they look like they are worn the same or is one looking more faded and burnt than the other?

by all means start with preamp tubes, maybe there's some fucked up shit in the front end... and maybe a speaker (the Cannabis Rex comes to mind for your application, but if you also want power tube drive at lower volume levels the Weber DT series of speakers is a great option, smooth and inefficient with a nice growl), but while you are waiting for your tubes like try to ascertain whether the amp is operating normally... I mean, you will wanna replace the tubes and probably the speaker regardless... speaking of the stock speaker, is it a ceramic Jensen? does it say anything on it? are you sure its original to the amp (has a fender logo on it)? maybe take a picture for me so we can decide whether it might be the culrprit or at least wether its part of the problem

do you have a schematic for the amp I can look at? if you post a clear schematic I'll tell you all about your amp and give you some ideas on potential 1 part mods to mellow her out... usually you can do a lot by cutting out a bright cap (the classic deluxe reverb mod) or replacing one here and there between stages to change the general response.... the size of the coupling caps is a close second to any RC networks in shaping an amp's frequency response, its probably beyond what you want to do to mess with any RC filtering they threw in (and given the era there is likely a lot, designers were really going apeshit back then), but you might be able to feed those sections are more robust signal by screwing with the simpler tone shaping sections, particularly those surrounding V1... have you loked at the guts? I assume she's a PCB design? is the board cramped, is it double sided? do the traces look robust enough to be soldering on? plus I wanna know if its a tweed or blackface topology... if its blackface style with the tonestack early and no cathode follower it should really sound great with a bridge pickup at like 5 and 5 and 5 at any volume and be clean to about 5, but if tis tweed/marshally then depending on the caps and stuff it might be behaving normally and you will wanna do the preamp tubes and then we'll see if there's some caps to snip or swap

so anyway, please read my tube recommendations and get me a schematic and we'll go from there. If you aren't in a position to get a better amp and you don't HATE this one you may want to dicker a little more.... its not like you're modding a vintage gem here and we're not talking about getting very intrusive

I realized after talking tubes that I am not super familiar with the super pro, but rereading your OP it sounds like it could need some basic maintenance (the amp is getting old and god knows how the previous owner treated it)... without looking at the schematic I can't be sure what its supposed to be doing though... but I just started typing whatever was running through my head here based on decades of tube amp experience, thinkin' out loud or in print or whatever

umm, how did you wind up with this amp? didn't you play through it before you bought it?

EDIT:

here we go, I found what we need!

http://ampwares.com/amplifiers/fender-super-pro-tube/

I should REALLY be working right now, but this is more fun. Holy shit this amp has too much circuitry... its a blurry schematic, we'll want a better one, but it appears to have a bright cap, its a little confusing because of the push pull on the clean volume and the poor resolution of this PDF... as you can see the 2 channels split early, right from C2 following a shared 1st gain stage, the gain channel has a whole 12ax7 upping the voltage, whereas the clean channel gets the other stage from V1 and there's also some resistors that are dropping the gain of that stage a bit to keep it clean.... then it hits the tonestack.... tis weird, usually in a blackface the tonestck would be sandwiched between the 2 gain stages with the volume pot, hmmm.... if you look at the gain channel its a lot like a blackface channel but because there's the shared V1A stage preceeding it, it behaves like a Mesa Mark1, which is just an extra triode out front of a blackface (more or less).... I guess the way they did the separate toenstacks on the channel they couldn't share V1A if they made the clean channel blackface style, too bad, because this topology is goofy for a clean channel.... okay, so they meet at the switch before C15 which couples the active channel to a 12at7 stage which buffers the FX loop, the enxt stage is recovery, basically like a reverb circuit... the jacks don't appear to be switching jacks so that buffer is always in your signal path, meh.... I cant tell what the FX send mix knob is doing, maybe it takes it out but it doesn't look like it, the recovery stage is always in for sure, but that's a lot like a BF with reverb, it effects the sound a little, makes it mushier but a little hotter and more harmonic... so then it ahs the classic long tailed pair phase inverter feeding the power section, just the standard BF 12AT7 type found on everything bigger than the Princeton.... and I kidna ignored the extra gain circuitry, tis got a buncha opamps in it, but I saw that coming, thatw as the era of the 900, ugh! if you stay off the gain channel they are not in circuit and from what I can tell depending on how you use the gain channel they will be outta circuit, they kidna slapped a boost or basic distortion in there, I can't read it well though.... in low gain mode though it appears to switch the solid state components out and w/o that stuff the thing is a 100% old school tube preamp, but the design is a little odd because of the way the switching is implemented... from what ic an see the gain channel makes sense assuming that the extra IC and RC circuitry down the bottom left isn't being used... we might wanna get a better schematic and compare the low gain circuitry to a mesa mark1 and see how it deviates as the mark1 is a really classic sound to be shooting for in a fendery amp

there's a lot to break or go off spec just in the pre, changing the sound from stock... and there's also a lot of room for user error getting sound as it does A LOT.... the circuitry shouldn't be eating your tone on the clean channel at least, though its not an ideal clean setup, its not sure if its blackface or tweed, kinda between them... it'll never sound like a blackface.... the FX loop is all tube but not a very good design in my opinion, but no 80s and 90s production amps have good loops... I am having trouble reading the component values to see if there's room to mod assuming the amp is operating on spec....

hrmmm

the amp would certainly sound better if the clean channel went straight to V1B with another stage after it (or better still if it had a big fat pentode front end and no additional gain like a Dr Z amp or or or, nevermind), skipping the shared stage and the volume control for clean could be moved to where the tonestack is.... you could lose any dropping circuitry and count on the tonestack losses to between stages to keep things clean using all the gain from V1B for blackface cleans.... but if you do that you lose the push pull pot for the volume as that switch needs to be where it is to work right, argh... I don't know that the amp will ever get the exact sound you want, but it may produce good sounds of its own if you embrace it for what it is and what it does... I certainly think the cleans have low headroom by design though.... what does the 'cut' do when you pull the clean volume? cut the gain?

Dr Jim is on the case man!

EDIT:

I just realized the channels are out of phase in this design, only active components (tubes and semiconductors) invert phase, so clean has 2 stages followed by 2 buffer stages while gain has the shared stage and 2 more stages into the same buffer.... why on earth did they do that? If you use this in a 2 amp configuration and switch channels on this amp one sound will be out of phase with your other amp no matter what you do making 1 channel useless in a bi-amp scenario.... out of phase channels piss me off, man! god, I woulda done this differently... early channel switching mesas have this design flaw too though, but I think they sorted it out by the mark IV. Its not a big deal except when you're mixing amps though.... it would drive me nuts, I like my channels in phase in any multichannel amp, switching or not. I swear I can fucking hear it anyway.

how ya making out with that 90s fender combo?

Ah, sorry for the late reply I've been busy with school. Thanks a ton for all the help and advice. I'm doing pretty well with it since I've learned to harness the sound a little by switching the EQ and not using hot humbuckers on it. Say, what do you think about the Music Man 212 65 watt?

is that one of the hybrid ones like the 120? If its the one I am thinking, it has a good clean sound, though its a little stiff. The transistor front end is part of it, but the power amp design is definitely one of Leo's firmest. Definitely in silverface fender turf for feel versus some of the other hybrids of the era like the hybrid Peavey Classics that have a bit more give. But the musicman amps definitely sound better to me, they have a nice hifi quality to the sound, they're just really unforgiving and hard to play into. Joan Jett still tours with one, they're very roadworthy. Come to think of it I have never seen a musicman of that era broken....

well, its good you're getting next to the 90s fender though, I think you just need to change your expectations of it

Yeah I guess I was expecting something kinda close to a blackface and all but just a little tweaked. And I'm considering one of those Music Man amps since I saw one for $450 at a guitar center. It works but it cosmetically shows signs of use. I think it's a late 70s model if I'm correct. Some bands I listen to use the 130s and I like their sound.

$450 seems high for a musicman, they sued to trade for $100 when I was a kid.... I'm sure they're worth more now, but I would try to keep it under $400 if I was shopping for one, especially one in rough cosmetic condition

they made a lot of them and they never break so I am sure there's more than enough musicman models that demand isn't outstripping supply, $450 just seems steep.... see if they'll haggle down 100 bucks