Choke Location and Safety

[daveottley]

Hello friends! I am going to choke my crack (a phrase I thought I'd never use) and I don't have any space on the underside of the chassis due to large capacitor upgrades and bigger diodes. I would like to place the chokes (I have two, one for each resistor in the stock kit) and I want to mount them on top of the chassis on either side of the tubes. One just "above" the volume knob and one just "above" the headphone jack. I have attached a picture here showing the location of the one choke above the volume knob. It is my understanding that it is best to isolate the choke from the chassis via standoff then wire it to the star ground point. I intend feed the three (+,-,ground) wires per choke through the ventilation holes in the chassis. Is this setup safe? I read somewhere that one would have to cap the choke to prevent shock. Any comments on this setup are greatly appreciated.

TIA.

 

[Paul Birkeland]

Mounting the choke on top is OK, sending the wires through the ventilation holes is not a good idea.  You'll want to add holes beneath where the wires from the choke protrude to give them a proper place to pass through, and a rubber insulating grommet is a good idea.  FWIW, if you don't hear any 120Hz noise in your Crack, the chokes won't make a huge difference.

 

[Tom-s]

I'd reconsider placing it underneath. Keep wires short and simple is the best method to prevent hum.
If you now introduce hum in your amp you've got a bunch extra unwanted holes in your top plate.
It may be better to rearrange the caps you have there in order to fit the choke in close proximity to the rest of the powersupply.

 

[ssssly]

Mine sits between the chassis ground and the RCAs on standoffs. I only replaced the first one though due to space constraints.

 

[daveottley]

That looks nice! What caps are you using? Is that Duelund wire?

 

[ssssly]

The caps are your run of the mil Russian PIOs.

The wire is unbranded. Picked up from Antiques Electronics Supply but Ive seen it unbranded in several other places as well.. It's tinned copper core with cloth braid over rubber. My buddy who restores old guitar tube amps turned me on to it. If you bounce around that world you'll come across it fairly commonly. It's kind of a bear to work with sometimes. But I like it.