New build: 5f2-a "Two Stroke" with 6L6

[theprofessor]

Finished the back panels. Now for sound samples...

 

[Peegoo]

That is looking really good. Have you really cranked it? A 6L6 in there stays clean and it's bright-sounding. Pop a 6V6 in and try it; it gets some really good grind going when cranked and is warmer sounding.

The layout you posted in the OP is the one I published as the change to Hunter's original 2-stroke. I built it and stuck it into a tweed head, but I figured it deserved to be a combo so I stuck it into a big Bluesbreaker-sized 1x12 cab with a Celestion greenback in it. The '63 Ford Falcon Futura badge adds real vintage tone It's the best-sounding amp I've made thus far.

 

[theprofessor]

That is looking really good. Have you really cranked it? A 6L6 in there stays clean and it's bright-sounding. Pop a 6V6 in and try it; it gets some really good grind going when cranked and is warmer sounding.

The layout you posted in the OP is the one I published as the change to Hunter's original 2-stroke. I built it and stuck it into a tweed head, but I figured it deserved to be a combo so I stuck it into a big Bluesbreaker-sized 1x12 cab with a Celestion greenback in it. The '63 Ford Falcon Futura badge adds real vintage tone It's the best-sounding amp I've made thus far.

I didn't know you were the one who posted that new layout! It was SUPER helpful! Thank you. I agree that this amp is remarkably good sounding. I think I'm going to stick with a 6L6 in there for now, at least. My first-ever amp was a 5f2-a, and I've built a couple of 5f1's, so I know what a single-ended 6V6 amp based on that topology sounds like.

From my perspective so far, this thing is remarkably versatile for such a simple design. The only thing I changed was the tone capacitor. Based on a tip from one of @jsnwhite619 's threads, I followed Rondo of Tweed Deluxe Speed Shop in changing the tone capacitor (not the bright capacitor) from a .0047μF to a .00068μF (680pF). See here. I had a few silver mica caps on hand and used the one that measured the highest (in my case, it measured 670pF). This really took of "the edge" of the treble, as Rondo calls it, and it distributes the available tones across the sweep of the pot in a nice way that allows for more fine-tuning and cuts or adds frequencies less rapidly. I'm a BIG fan of that mod.

I've still got a JJ ECC83 in V1, and so I may start to roll a few others into that position to see what things sound like. But with the tone capacitor swap, the JJ could live in V1 and sound great. And now I can really crank it without raising the levels of icepick. With a 6L6 it holds together really well very far up the dial. It feels to me a lot like 1/2 a Low Power Tweed Twin: one 6L6, one 5U4GB rectifier, and one 12" speaker. I'm a huge fan of what I'm hearing.

If I were to build another, I think I'd put in a humdinger pot. There is a punch-out already in the blank space between the board and the PT where it could be mounted easily. That might be able to reduce filament hum just a bit.

 

[jsnwhite619]

It's a fun one isn't it?!? I've learned that the volume knob sweep is a big factor in how those amps behave. There's a lot of great clean and overdrive in there to be found, but the pot choice decides how much of which one. I've tried both ways - clean to 8-9 then all the overdrive at the end, and screaming at 6 and the rest of the wat to 12 basically was just adding bass to it.

I had forgotten about that mod on the tone cap - I did it to my 5e3 years ago, but I don't know if I've used it again since.

Plug that amp into a stout speaker or cabinet and get ready to wake the neighbors!

 

[Pops_Caster]

Well-done project. I’d like to try building an amp when I retire (hopefully next year). Any recommendations for part sources?

 

[theprofessor]

Well-done project. I’d like to try building an amp when I retire (hopefully next year). Any recommendations for part sources?

Thank you! I like Tube Depot and Doug Hoffman's store. For the chassis, I used Mojotone. Those are my go-to places for sourcing amp parts.

 

[Pops_Caster]

Thank you! I like Tube Depot and Doug Hoffman's store. For the chassis, I used Mojotone. Those are my go-to places for sourcing amp parts.

Thanks, professor. I’ll check them out.

 

[theprofessor]

REPORT: I've been rolling some tubes through V1. It seems to me that the choice here is based on what you want in terms of gain/distortion characteristics and treble response (gainy/bright/piercing vs. sweeter/natural).

All the 12ax7s I've tried are pretty much going to do the same thing, despite their tonal differences: the amp is going to respond better early on the dial; it's going to start to break up earlier on the dial; and the distortion is going to be more buzzy/blotchy as the volume goes up. I put a Sylvania triple mica blackplate 5751 in there, and it was a good compromise, gain-wise, between a 12ax7 and a 12ay7. But it was not as clear or the treble as sweet as the 12ay7 I've tried. I am now sticking with a 1953 GE box plate 12ay7 in V1. You've got to get it high on the dial to get much response out of the amp, but when it does respond, the gain characteristics and distortion type are just "right" sounding to me. Sounds like a good overdriven tweed sound to my ears -- that is, like a low power tweed Twin type. It's got some hair on it, but it holds together. The volume can live between 8-12, and it's plenty loud. Then you can use the volume control on the guitar and the different switch positions to get different sounds. But even up to 12 on the volume, the amp overdrive with single coils always sounds good, clarity is maintained, and the treble stays sweet, never harsh.

 

[theprofessor]

Almost finished with the cabinet.

 

[Snfoilhat]

Nice, what is that coating?

 

[theprofessor]

Nice, what is that coating?

Thanks! It's Rust-Oleum Multi-colored Textured Spray paint. Autumn Brown. It looks a lot like leather or stone, and it's rough to the touch. Very difficult to apply, but it's a cool and unique finish, in my opinion. It should be super tough, too.

 

[theprofessor]

 

[screefer]

Nailed it!
Uniquely yours

 

[Kevin Wolfe]

5751

 

[6stringcowboy]

Thanks! It's Rust-Oleum Multi-colored Textured Spray paint. Autumn Brown. It looks a lot like leather or stone, and it's rough to the touch. Very difficult to apply, but it's a cool and unique finish, in my opinion. It should be super tough, too.

What is the difficulty in applying the textured paint?

 

[theprofessor]

What is the difficulty in applying the textured paint?

It is finicky in terms of how it lays down, due to the texture in the paint. These cans have to be shaken quite thoroughly, and the temperature suggestions for application should be followed pretty strictly. Due to the texture, the nozzle is big, and that means that you blow through a can really fast. If too little texture comes out, you're getting only the base color. And you have to spray from a greater distance than is typical for regular Rust-Oleum spraypaint, to avoid pooling.

 

[6stringcowboy]

It is finicky in terms of how it lays down, due to the texture in the paint. These cans have to be shaken quite thoroughly, and the temperature suggestions for application should be followed pretty strictly. Due to the texture, the nozzle is big, and that means that you blow through a can really fast. If too little texture comes out, you're getting only the base color. And you have to spray from a greater distance than is typical for regular Rust-Oleum spraypaint, to avoid pooling.

Thanks!

 

[Esquier]

One thing you can do with that is to clip the cap in, wrap one hand around the AC cord running to the amp, and gently pinch the cap with thumb and finger of the other hand. You will hear a difference that way.

Thanks for that! I was having a heck of a time finding the outer and had given up

 

[Peegoo]

If you like the look of seamless pebbled Tolex but want it dead easy to apply and repair, aerosol pickup bed liner works like gangbusters. Prime, sand, and paint. It's very tough and does not peel loose or tear when bumped.

I used it on this homebrew Leslie cab:

 

[theprofessor]

Custom cabinet size means custom cover. I had Tolex, so I made one.