Keith,
I'd love to play through that amp when you're done. Should I pray for rain?
Hope all is well with you.

Ken Oettinger
 

Very nice. I'll be monitoring your progress. What's the plan for speakers or are you going to make this into a head?
 

I am not as picky about speakers as some people. I will use cheap speakers. If the amp sounds good enough, I will look around for some high end speakers.

As far as configuration, the output transformer has taps for 4,8, and 16 ohms. I can do just about anything. The Super used one 12 and the pro used two 12s, but 2-12s are heavy. I might set it up with 4-8s so that it is light. The 4-8s would move the same air as about 1-1/2 12s.

I am putting it into an ugly utility chassis and will build a combo around the chassis out of plywood.

I expect to get some time over Thanksgiving to make the chassis and test the circuit.
 

Did you get a chance to finish the amp and test it out? If so, how'd it sound? Would you mind sharing how you made up the tag board and cicuit diagram? Thanks!
 

It's still sitting on my workbench. I am hung up on what to use as a chassis.

I bought some steel studs used in commercial construction that looked the right size, but they are too flimsy. I am ordering a sheet metal bending brake ($39.95 at harbor freight), but I can't buy it until after Christmas bills are paid off. I will make a chassis out of sheet metal scraps with the brake.

I have the tube sockets, tubes, and transformers that I've robbed from various flea market amps. I also have a set of Bassman reissue transformers that I picked up cheap off of eBay that I might use. I have the on-off switch and a fuse socket.

I have several empty amp cabinets that I've picked up, including a 12 inch Fender solid state without the chassis and a premier 120 cab with no chassis.

All that is holding me up is the lack of free time and a chassis.

When I am done, I will publish an improved layout. I have a fender style layout for the Premier twin-8 which I might do also as a beginner kit.

My goal is to have the complete instructions, graphics and parts lists as a web page each time I finish an amp.
 

Hi Keith!
I'm an amateur harp player and I've built (DIY) a few tube amps for myself.
http://www.flickr.com/photos/38383652@N00/
Next on my to do list is 6L6 push-pull amp, precisely speaking 5D4 or 5D5. I have Ted Weber's 4k/4 Ohm OT but I don't know which impedance to shot for 5D4 or 5D5 (8k with 8 Ohm speaker - which I have or 4k with 4 Ohm speaker - which I'll have to buy).
Voltages on 5D5 (5D4) layout suggests Class AB1 with 8K load but I'm not sure. The problem is my salvaged PT (350V-0-350V; 125 mA). PT could only fit Class AB1 (380V on plates, 270V on screens, 250 Ohm cathode resistor, max plates and screens current < 120mA and 9k load).
Is 8k impedance I should go for in 5D5?

One suggestion: You might try to replace 56k resistor with pot as Gerald Weber suggests in his article Harp Amp Secrets.

Thanks

Branislav
 

Hi Keith!
I'm an amateur harp player and I've built (DIY) a few tube amps for myself.
http://www.flickr.com/photos/38383652@N00/
Next on my to do list is 6L6 push-pull amp, precisely speaking 5D4 or 5D5. I have Ted Weber's 4k/4 Ohm OT but I don't know which impedance to shot for 5D4 or 5D5 (8k with 8 Ohm speaker - which I have or 4k with 4 Ohm speaker - which I'll have to buy).
Voltages on 5D5 (5D4) layout suggests Class AB1 with 8K load but I'm not sure. The problem is my salvaged PT (350V-0-350V; 125 mA). PT could only fit Class AB1 (380V on plates, 270V on screens, 250 Ohm cath. res. and max plates and screens current < 120mA and 9k load).
Is 8k impedance I should go for in 5D5?

One suggestion: You might try to replace 56k with pot as Gerald Weber suggests in his article Harp Amp Seckrets.

Thanks Branislav
 

The 5D4 used one 8 ohm speaker and the 5D5 used two 10 inch 8 ohm speakers in parallel (4 ohms). I don't remember where I read this, though. They are the same amp except for the transformer.

This is what I did on the last 5D4 that I made. I used a bassman reissue power transformer and the blues-deluxe output transformer with the 5d4 circuit. I replace the 56k resistor with a 10k resistor in series with a 100k pot. I labeled it "mojo", but I found that fiddling with the mojo control made no big difference in tone or feedback. I replaced the 12ax7 on one channel with a 12au7. The amp, probably because the power transformer was higher voltage than spec, was very loud. It had a buttery smooth tone without much distortion. Everyone complained that my harp playing was too loud - heaven!
The only negative was that heater wiring was a mess and I didn't know that you should twist them. All the wires were too long because I used an old chassis with the tubes in the wrong places. It hummed, but not too badly.

I bought the Blues-Deluxe fender transformer from Angela.com because it has taps for 4 and 8 ohms at a lower primary impedance (like a tweed amp) and it only costs 38 dollars. They rape you on shipping, though.