Suitable choke for a 5F1 Champ?

[Mark]

Hi

I’m wondering what would be a suitable choke to knockout the 50/60hz in a Champ. I had thought that a Twin Reverb choke would fit the bill.

I know Mercury Magnetics make a small choke for such amps, though it seems a bit small for the task.

http://www.classictone.net/40-18003.pdf

What are your thoughts?

This speaker might be a good match for a Champ or Tweed Princeton amp.

https://wgsusa.com/g12q#reviews

[martin manning]

Deluxe Reverb choke has been used.

[Stevem]

What will help the most with a real champ in regards to 60 HZ hum levels is to twist tight and run 2 heater wires to each tube socket and do away the heaters being grounded to the chassis!

[thetragichero]

yes the smaller fender choke will do
if you shop antique electronic/amplified parts they're about ten bucks

[Mark]

Thanks for your help. Champs and Princeton’s are noisy even after the heater mod is done. The choke and shielded cable makes a big difference.

Looking at the specs, the choke is good for 50mA and the 6V6 will pull nearly 40mA with a 360vdc supply.

http://www.classictone.net/40-18040.pdf

[martin manning]

So, 10mA left to power one 12AX7. No problem.

[didit]

Hello -

Had good success taming single-ended amp hum with https://www.hammfg.com/files/parts/pdf/158M.pdf fed with silicon rectification, and before the first primary filter cap. Duncan Amps PSU design tool - http://www.duncanamps.com/psud2/ - was helpful in modelling minimal AC ripple.

Best .. Ian

[Colossal]

I would utilize a Pi filter (C - L - C) before B+1, meaning, the entire power supply sees the choke, not just the screen(s) and preamp. Makes a huge difference. I used a 10H 70R 200mA choke for a big bottle SE amp and it was very, very quiet. I would only build SE amps with a Pi filter as noticeable hum is not really acceptable to me.

[ChopSauce]

Doesn't that (CLC filter) cause a significant voltage drop?

[Colossal]

Doesn't that (CLC filter) cause a significant voltage drop?

Depends on the DCR of the choke. An LC choke input supply definitely will drop significant voltage. But most Champ builds and kits I have seen run stupidly high voltages (incorrect PTs) on a 6V6 and sound harsh and strident with awful blocking distortion. So losing some voltage is definitely desireable, unless the transformers have been properly specified. To get a low DCR on the choke with a decent amount of inductance, a fairly large wire gauge would be used, making for a big choke. Champs were budget amps and IMO, sound terrible above about 3 on the Volume knob. But there is no reason a single ended amp should sound bad or hum or have awful blocking distortion, if properly designed. That is just the stigma they get because of all the terrible "practice amps" built with grossly undersized components.

[ampdan]

Champs were budget amps and IMO, sound terrible above about 3 on the Volume knob.

What were they thinking using them on all those recordings...

[Mac Dillard]

Don't claim to know a whole lot about chokes. The only one I ever use for a 5 watt SE amp was a Hammond 156L. 5H, 135R, 75 ma, 400 volt. Worked pretty good..Heater wiring layout (twist and two wire) and DC heater elevation seems to work for me to build a quiet SE amp.

[Colossal]

Champs were budget amps and IMO, sound terrible above about 3 on the Volume knob.

What were they thinking using them on all those recordings...

Well, I've listened to Layla and Rocky Mountain Way and while I much prefer the latter, you can tell they are a Champ and where the mic is placed, etc. I am most impressed by what Julian Lage gets out of his.

[Mark]

The Hammond 159S seems to fit the bill as a suitable choke.

https://au.mouser.com/datasheet/2/177/1 ... 736947.pdf

[thetragichero]

lol 159s would be a suitable choke for a 100w Marshall