Bright Switch wiring (again...)

[Colossal]

This may have been addressed in a previous thread and, if so, I apologize for bringing it up again. I have read the Bright Switch discussion comparing Francesca and Kelly bright switch wiring. However, I'm wondering if using a DPDT On-Off-On and soldering the bright caps between the poles would have any advantages or disadvantages versus the traditional method (Kelly wiring). This would just eliminate having the cap leads "flying" between the switch and volume pot (wiring would still be Kelly). I've attached a drawing illustrating what I mean. Again, if someone has brought this up previously, tried it, hated it, liked it, or has any comments, I would appreciate hearing them.

This is non-purist of course and feel free to shoot it to pieces if you like.

[Richie]

looks cool to me, i'm doing some mod experiments to an express soon, i'll have to try it. Looks like part of the Dumble idea thing.

[Colossal]

Thanks Richie. I'm not looking to mess with a good thing but was thinking about what if... I tried this with SP3T switch on a marshall build to be able to switch between 100, 250, and 500pF and it worked well. Just wondering if someone had tried using a DPDT in an Express. The caps could be oriented parallel to one another (flat sides parallel) or at opposite ends of the switch (as shown) if field effects come into play. They shouldn't though as only one cap is in the circuit at a time.

[paulster]

It'll help to a greater or lesser extent but the input to the volume pot is a reasonably low impedance anyway (in tube amp terms), which is why there's a big difference between the cap being left on the wiper versus the input.

Get the volume into the cooking zone (around 1-2 o'clock) and the volume pot value is approx 500K from the wiper to either end of the travel, so you've got a minimum source impedance of 500K at that point without even factoring in the original source impedance. That's why it's so susceptible to noise when wired the Francesca way.

I'll be interested to see whether this makes an audible difference, but I still like it regardless as it means a more stable mounting for the caps, which have pretty flimsy leads, especially the 100pF cap.

[Colossal]

I'll be interested to see whether this makes an audible difference, but I still like it regardless as it means a more stable mounting for the caps, which have pretty flimsy leads, especially the 100pF cap.

Paul, thanks (as always) for weighing in. My interest in this primarily was for a more rugged approach to mounting the caps (also, my OCD likes neatness when possible LOL). Soldered to those little NKK DPDT switches, the micas are nice and solid and very discreet.

The way I've drawn it is the Kelly way, right?

[Richie]

but, the solid wire/caps used here, is vibration prone,and when the caps are wired the old way, you have to watch for this. So, i see this as might help in some amps.

[M Fowler]

Dave,

I like your way of wiring the caps and I will give that a try especially in my Express combo which this may help in that small channel chassis type of environment.

Good work.

[Colossal]

Dave,

I like your way of wiring the caps and I will give that a try especially in my Express combo which this may help in that small channel chassis type of environment.

Good work.

Mark,

Thanks. I'd be interested to know what you think if you try this arrangement in your combo, especially since the speaker is roaring away so close to the amp

[M Fowler]

Dave,

I'm wiring on my new Normster Rocket Reverb build and decided to add this switching in, but I won't finish this amp until this weekend.

I'll have to get another switch to try it in the Express combo.

[Ron Worley]

I like it- not the KF spec, but actually a better mouse trap and surely easier to build than what Ken did. Good thinking... might have to use this in my next build...

[paulster]

The only change I'd make, and this is really nit-picking, would be to wire the wiper wire to the side of the switch closest to the volume pot to shorten its wire as much as possible since this is the more sensitive one.

Other than that it's a great idea and a better solution than Ken's.

He would be proud of the spirit of continuous improvement.

[Cliff Schecht]

I'm really digging the amount of detailed discussions we've been having around here. It's fun to take something so infamous and pick it apart piece by piece to figure out what makes it magic. While our builds may not currently be KF approved, perhaps they will be in the near future!

[M Fowler]

Ken F. gave his blessing to the forum not to clone but go beyond what he had done and this is an example of doing just that.

Mark

[Colossal]

The only change I'd make, and this is really nit-picking, would be to wire the wiper wire to the side of the switch closest to the volume pot to shorten its wire as much as possible since this is the more sensitive one.

Other than that it's a great idea and a better solution than Ken's.

He would be proud of the spirit of continuous improvement.

Thanks Paulster and All.

Ok, I revised the drawing to include Paulster's suggestion. That makes good sense. Let me know if you see any other ideas for improvement.

Regards,
Dave

[Structo]

I like it!

I may have to borrow that idea.