Turn Bassman into Super Reverb?

[The New Steve H]

I guess I am the all-time king of dumb questions, but here goes.

I wanted to build my first big amp, after a Firefly and a submini job. I looked into the Fender Bassman, and a guitarist told me it was the "holy grail" of clean tones. Sounded okay to me. I bought the parts and went to work.

Then I checked out a Gerald Weber video. He said the Bassman could NOT produce a clean tone, and he also said the tone stack was ineffective because of its location in the circuit.

I've been looking at schematics. It looks like a Super Reverb with no internal reverb or vibrato is extremely similar to a Bassman. Change a few parts here and there, and you've turned a Bassman into a Super Reverb minus the effects.

Am I better off doing this than creating a Bassman clone? I haven't checked to see if the transformers and choke will work--I just had this idea and I need to get to bed--but I can get new ones if necessary.

What I want is an amp with a good clear tone that takes pedals well and which sounds great with a little blues overdrive. I like sparkly chimey sounds. I have zero interest in metal or heavy distortion; I am an old fart and I don't want to make a lot of noise.

[xtian]

Then I checked out a Gerald Weber video. He said the Bassman could NOT produce a clean tone.

Uhhh... Haven't heard that one before. Wow.

[dreric]

What I want is an amp with a good clear tone that takes pedals well and which sounds great with a little blues overdrive. I like sparkly chimey sounds. I have zero interest in metal or heavy distortion; I am an old fart and I don't want to make a lot of noise.

The decription above = Fender Bassman!

Not trying to be a smartass, really..... a good bassman will do exactly what you're asking for.

What year model Bassman do you have? Assuming that it's a head, filter caps, good tubes and making it "blackface spec" make for a pretty awesome amp.

If memory serves me the Bassman is working into a 4 ohm load while the super is into a 2 ohm load (double check that). While the circuits are pretty similar the different OT makes for a very different amp.

I'd clean up the Bassman see if it's what you want, if it's not then its a good platform for mods.

Eric

[Gaz]

Could Weber be comparing a tweed Bassman to a blackface Super Reverb? If so, it'd make a little more sense. Of course he's being a bit hyperbolic because any amp can produce a clean tone of some kind. The bit about the locus of the tonestack makes me think that's what he meant. The TS is less effective in 5F6-A because it is less lossy (due to the cathode follower). The tweed also has less headroom in the preamp. JM2C.

So, if you started with a blackface era Bassman changing to a Super won't be any difference. If you started with a tweed, then yes, you will have more effective tone controls, and more headroom for pedal consumption.

[rdjones]

The Bassman has gone through quite an evolution in it's circuitry.
So you (and he) have to be just a bit more era-specific to be properly understood.
Tweed, Brown/Blond, Blackface, early Silverface, late Silverface ultralinear ?
They each have their own character, and all can be played "clean".

My "HolyGrail" moment was with a 6G6B when I was a teenager, and the amp was just a couple years old.
I never forgot that sound.

Tone is highly subjective, but I'm truly hoping GW's comment might be being taken out of context.

The AA864 pretty much nails the Fender clean tone.

rd

[Craig B]

My tweed Bassman does a very nice clean. It does not have the blackface scooped mids that many others like in a clean amp. Tweed clean is full and rich. Gorgeous rich with a stringy overtones that nothing else has. When I crank it the sound goes to full rich blues sound. Mine is in a smaller cabinet with two 10s instead of four 10s. I've run it through a single 12 and it loses some of the richness. My voltage is a little lower too (426 DC) because I used Hammond transformers. I added a post phase inverter master volume that works very well with the circuit. I also added the Hoffman hotswitch for extra overdrive and the Western Electric reverb but don't use those features very often. The tone controls don't have as much range as the blackface controls do. But they give me all the sounds I want so I don't have the complaints Gerald Weber voiced. I have built two other amps since the tweed bassman but haven't been able to create that sound with other circuits.
Good luck with your planning and building!

[The New Steve H]

Maybe I misunderstood what he said.

I don't have a Bassman. I'm BUILDING a clone. I just figured it would be stupid to solder it together before finding out if I could use most of the parts to build a more suitable amp.

Thanks for the input; it sounds like I'm building exactly what I need.

[rp]

I like sparkly chimey sounds. I have zero interest in metal or heavy distortion; I am an old fart and I don't want to make a lot of noise.

You might want to consider a cathode / fixed bias switch. Easy to do with a DPDT.

If I was building a 5F6A to gig steady I wouldn't bother, excepting Vox styles I think most big amps sound better w/ fixed bias. If you are building a geezer amp for playing around the house, recording, jamming w/ buddies, the cathode option is real sweet here.

[The New Steve H]

This thing will probably be too loud for me to play in the house no matter what I do to it. I'm okay with that. I'm building it to learn, more than anything.

When I said I didn't like noise, I just meant that I don't want to play loud obnoxious rock.

[Firestorm]

When Gerald talks about amps that can't do clean, he's usually talking about amps with paraphase inverters (which pretty much can't do clean). The 5F6A definitely has nice cleans (if the speakers don't distort early), but you have to be a little careful. With the volume all the way up on that circuit, you have two cascaded gain stages with very little attentuation between them -- voltage gain is something like 1000 even with a 12AY7 in V1 -- so you don't want to hit the input too hard and you do want a good 12AY7. If the tone stack is too midrangey, you can get back some of the scoop by changing the slope resistor to 100K instead of 56K. You can make that switchable. And if the power amp is distorting too quick, try dropping the 220K grid loads to 150K or even 100K. Works wonders sometimes.

[The New Steve H]

Great advice. Thanks.

I do want distortion, and I do want an edge to it, but I expect to get most of that from my pedals (Fat Sandwich, Plimsoul, and Blues Driver).

I bought a 12AX7 and a 12AY7 for the first stage, so I guess I'll figure out which one I like best.

Incidentally, Weber says there is no point in using a 12AY7, because the 12AX7 gives you more gain, and you can turn down the gain and get everything you would get from a 12AY7. Don't know if this is right. He also says it's hard to find good 12AY7s.

[Gibsonman63]

You never said which bassman you are building. The tweed and black face bassman amps are different animals, but both great sounding in thier own way.

You can get huge differences in tone out of the Fenders with different speaker and cabinet configurations. Mine sound horrible with any kind of celestions (to my ears) but really chime with Jensens.

Just build. Then hit up all of your friends and try every speaker cabinet you can get your hands on. Then tweak to taste.

[The New Steve H]

It's a 56fa. Dang it. 5f6a.

I have a friend who wants an amp based on the Super Reverb, and I thought this Bassman would be a good project for me, to get me up to speed on big amps.

He wants lots of clean headroom, but he is not interested in vibrato, so we are thinking about building a Super Reverb type amp with the vibrato junk completely omitted.

[rp]

Firestorm speaks truth - NOS 12AY7 for a Fender sound. 12AX7 is great too, and will give you that Marshall thing. If your 5F6A works out well and you find the right speakers you may leave your pedals behind, except maybe a good clean boost.

Incidentally, Weber says there is no point in using a 12AY7, because the 12AX7 gives you more gain, and you can turn down the gain and get everything you would get from a 12AY7. Don't know if this is right. He also says it's hard to find good 12AY7s.

This is always true, isn't it? Turn the guitar volume down, plug into the low input, use lower wind pickups... Nonetheless, the 12AY7 is the right way to clean tweeds up IME.

An other really useful mod here (mind you I usually hate lots of mods and switches) is the Marshall .68 bypass cap on V2 switched on a pull pot. Try it when you are done, just tack on the cap. You can put it on a foot switch and now you need even less pedals.

[The New Steve H]

I am trying to figure out what you're describing, RE the Marshall mod. I figured you meant Marshall added this when they created the JTM45, so I DLed a schematic, but I can't find a .68 ohm resistor or a potentiometer near V2.