5F1 Champ build diary.

A cursory look. I'd change a few things.

If there is no heater CT on the PT. Place the 100 ohm resistors directly on the 6V6 socket from pin7 to pin8 and from pin2 to pin8. (Neater and less wire running around.)

Swap the positions of the 6V6 Bias resistor and cap. The bias resistor gets hot and all of the caps can be next to each other without a hot resistor between them.

You forgot running the power to V1 plate resistors.

Run the heater wire directly across the V1 socket to pin9, keeping the heater wires twisted all the way to the socket.

Extra points for running the red OT wire directly to the rectifier pin8. (less wire).

 

If you decide to use the 8uF cap, go 20-10-10-8.

 

I like your speaker choice!

 

Hah. Maybe I should try the *attractive sticker* method of choosing a speaker. The *listening to sound clips* method has not worked out too well for me.

 

That's a well-planned amp. I admire your drawing skills. For sure I agree with @Lowerleftcoast. Well spotted sir!

I've never looked at an actual Champ chassis to see if there's space to mount a separate power switch and keep that 120V away from the pot. It'd be smart, noise-wise, if it could fit. And, detail, don't know what type resistors you plan to use -- IME the one place it *really* matters in the signal chain is the input resistor and 68Ks -- carbon comp there contributes a ton of hiss *that gets amplified* and I found MF (or at least CF) were clearly, audibly much quieter.

For sure I'm no eagle-eye like LLC. But without going point by point on yours, I always compare mine for spacing and routing to my personal gold standard, Rob's layout.

 

^^^^
Agree with King Fan. A separate power switch would help to keep the 5F1 quiet. Maybe put the fuse somewhere else and put the power switch in the fuse hole?

 

Compare your ground bus to the one in the layout posted by @King Fan - it's worth it to separate the ground for the 3rd filter cap and make it part of your pre-amp ground bus.

In your picture it looks like you've got the poweramp and preamp grounds connected.

 

Consider this common mod to take some stress off of the rectifier tube (longer life). You will find an explanation in the Rob Robinette site *5E3 mods*.



If you will be purchasing a few extra parts, like these diodes, a 470k (any wattage) 6V6 screen resistor is sometimes desired to get rid of blocking distortion which is common for the 5F1. (You don't have to install it but it is nice to have it on hand.)

 

LOL, good idea. This is a Champ, so 'KISS' and 'the perfect is the enemy of the good' both apply. If ever there was an amp that didn't even need a faceplate, this is it. And your layout is already way ahead of most kit-company layouts. Carry on, and enjoy.

 

Looking forward to your Laser etched face plates. Do you think you will venture into pedal box etching?
Sorry to hear about the divorce.

 

When 5Y3 is used without choke there should be 50 ohm current limiting resistors on both anode circuits for voltages up to 400VAC and 140 ohm when AC voltage is higher. Some NOS datasheet also has max 10uF limit for the capacitor. Some new 5Y3 datasheet allow 20uF but they also recommend current limiting resistors. When choke is used resistors are not needed when choke lengthens the time the current flows and it also makes DC voltage more stable for different currents than resistive circuit but choke also decrease the voltage.

Also those already earlier mentioned silicon diodes are good protection!

Current limiter resistors increase the time the current flows to capacitor(s) and the rest of the amplifier when it "flatten" sine vave peaks and then they increase rectifier tube servise life but they also reculate DC when there comes RC circuit with the first capacitor although there is rectifier tube between Resistor and Capacitor

 

Aha, nice score -- what I believe is vintage-correct 17K:4ohm 5W, and AFAIK worth getting from ClassicTone.