Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: echuta13 on August 30, 2021, 02:39:47 pm

Title: Coupling cap switch options
Post by: echuta13 on August 30, 2021, 02:39:47 pm

I was interested in putting some feelers out on a better way to switch coupling caps (plus prevent popping and high voltage on the switch). 

The graphic shows how I am currently doing the switch (which is okay), but the updated version I think would be better and maybe one less part...  Maybe..

Any thoughts or insights on this?  Should there be a resistor across the switch in the improved one as well?  I have also seen a 10M resistor placed between the caps going to ground to prevent any noise as well.
This is just pencil pushing for now.  Need to clean off the work-bench before I can actually mess with this.

Title: Re: Coupling cap switch options
Post by: brewdude on August 30, 2021, 03:54:58 pm

The updated version is similar to the way Dumble employed the mid boost function on his ODS’s.  I would suspect a large value resistor would be helpful to silence switching pops.

Title: Re: Coupling cap switch options
Post by: pdf64 on August 31, 2021, 03:13:47 am

A 10M resistor to reference each node to 0V should stop pops.

Title: Re: Coupling cap switch options
Post by: tubenit on August 31, 2021, 03:49:06 am

Dumble style

Title: Re: Coupling cap switch options
Post by: echuta13 on August 31, 2021, 11:55:57 am

Thanks everyone for the confirmation!
 

Title: Re: Coupling cap switch options
Post by: roseblood11 on July 27, 2023, 09:17:43 am

Why does Dumble do it like this? Leaving one side of the 390p unconnect in the "mid boost" position will cause some popping, right? Why doesn`t he leave the cap connected at both ends and just jumpers it wit the switch?