What to do with ground switch hole?

quackerz · June 14th, 2007, 10:52 PM

Next week when I have the time, I'll be converting my Deluxe Reverb to a 3-prong power cord. So, what does everyone do with the now function-less ground switch? Off the top of my head, there's a bunch of easily reversible mods that can be installed there:

- Mid pot
- NFB pot
- NFB lift switch
- Presence pot
- Channel jump switch
- Vibrato on/off switch
- PPIMV

Suggestions? Or should I just leave well enough alone (where's the fun in that)?

Thanks,

mr_hankey · June 15th, 2007, 05:32 AM

I'd go for a NFB pot.

Jef · June 15th, 2007, 08:10 AM

or a dwell pot for the reverb...

11 Gauge · June 15th, 2007, 11:25 AM

Tone stack bypass switch.

Wally · June 15th, 2007, 11:28 AM

+2 on the NFB.

PhatTele · June 15th, 2007, 11:33 AM

Mid-range pot. Use a 25K audio taper. Attach the 6.8K resister from the Bass pot to the middle lug of the midrange pot. Ground the other end to the casing. Run a lead from the Bass pot (where the resister had been located) to the left lug of the midrange pot (looking at the back with the lug pointed up). On zero or one, the tone is "stock." Anything above stock is adding midrange. It's a nice mod which gives you a nice bluesy crunch without giving up the stock tone.

Note: If you run the lead to the ground switch jack, you might need a shielded cable. Sometimes you might get a little feedback (not always) if you run the lead unshielded. If you put the midrange control in place of the second output jack, you typically don't need the shielded cable.

JohnnyCrash · June 15th, 2007, 12:12 PM

Quote:

Originally Posted by Jef

or a dwell pot for the reverb...

+1

Or the NFB and Mid controls sound good too. Hard choice.

If the amp rocks, I might say just leave it be... I'd be more for leaving it alone than for a mod actually.

jjmantele · June 15th, 2007, 02:23 PM

I used mine to install a female stereo 1/4" jack. It's wired to the cathodes of the power tubes on which have 1ohm resistors inserted to ground. I can insert a male stereo jack in it and connect my volt meter to measure/set bias, w/o pulling the chassis.

quackerz · June 15th, 2007, 02:30 PM

Quote:

Originally Posted by jjmantele

I used mine to install a female stereo 1/4" jack. It's wired to the cathodes of the power tubes on which have 1ohm resistors inserted to ground. I can insert a male stereo jack in it and connect my volt meter to measure/set bias, w/o pulling the chassis.

Yeah, Weber even sells all the stuff to do that as a kit. That's another consideration...

LPBlue · June 15th, 2007, 05:33 PM

How about a pentode/triode switch for a 1/2 power option?

Ben Harmless · June 15th, 2007, 05:38 PM

Install a "destroy all humans" switch.

Seriously.

If you like the amp, don't mess with it. Plus, while all those mods might be easy to wire up, unless you or a tech looks very carefully at getting the lead dress right, you're opening up a whole can of man-eating worms - seeing as how that hole is probably right next to the power tranny...

NFB/presence prolly wouldn't be too bad, but a mid knob might be a problem, and a channel-jump switch would almost certainly be a nightmare.

Now I'm absolutely going to put a "destroy all humans" switch on my next amp.

dibber124 · June 15th, 2007, 05:59 PM

I like the NFB Switch. Back in the early'70s we called it the "Clapton Switch"!

JohnnyCrash · June 15th, 2007, 08:43 PM

Quote:

Originally Posted by jjmantele

I used mine to install a female stereo 1/4" jack. It's wired to the cathodes of the power tubes on which have 1ohm resistors inserted to ground. I can insert a male stereo jack in it and connect my volt meter to measure/set bias, w/o pulling the chassis.

+1

I change my vote to this.

Ease of use/maintenance on an amp that already sounds great is always good. It's like a Tele - functionality and simplicity.

quackerz · June 16th, 2007, 06:26 AM

Well, maybe I'm getting old then. I just re-tubed and biased the thing, and holy crap! It sounds way better even with the original Oxford than my '64 no-logo ever did. Then again, I knew nothing about amps when I owned the '64 and did nothing except replace the power tubes when they failed. Bias pot? I turned it until it sounded good without smoke and flame. Maybe that's why I went through a lot of power tubes... Hahahaha!

I'm gonna do the bias test point thingy. No sense making a great amp sound like something it's not. So how do you read plate voltage without pulling the chassis?

The "Destroy all Humans" switch is still VERY enticing.

Thanks for that, Ben!

jjmantele · June 16th, 2007, 09:33 PM

Quote:

Originally Posted by quackerz

I'm gonna do the bias test point thingy. No sense making a great amp sound like something it's not. So how do you read plate voltage without pulling the chassis?

Good question. I actually have not changed tubes since I installed it. I know it runs about 10% above the schematic but what I'll end up doing is measuring the plate voltage at a few bias levels and noting it along with the idle current. Excel is nice for this since you'll see the wattage too. Then I'll know the plate voltage at various current levels and I'll only need to know the current in the future, to know the whole picture.

quackerz · June 17th, 2007, 03:10 PM

Thanks, gotcha. But even though I work in IT, I suck at Excel macros. I was considering mounting two plate voltage test points on a plate that would cover the accessory receptacle socket but I completely chickened out. I ended up leaving all as is with the exception of installing an 18" male power receptacle cord and leaving my 1 ohm resistors in there. I wanted more play time on Fathers Day.

June 14th, 2007, 10:52 PM	#1 (permalink)
quackerz Tele-Holic Join Date: Sep 2006 Location: New Jersey Age: 45 Posts: 921 8 Photos	What to do with ground switch hole? Next week when I have the time, I'll be converting my Deluxe Reverb to a 3-prong power cord. So, what does everyone do with the now function-less ground switch? Off the top of my head, there's a bunch of easily reversible mods that can be installed there: - Mid pot - NFB pot - NFB lift switch - Presence pot - Channel jump switch - Vibrato on/off switch - PPIMV Suggestions? Or should I just leave well enough alone (where's the fun in that)? Thanks,

June 15th, 2007, 08:10 AM	#3 (permalink)
Jef Tele-Holic Join Date: Mar 2003 Location: Antwerp, Belgium Posts: 665 1 Photos	or a dwell pot for the reverb... __________________ It'll hurt tomorrow but tonight it hurts so good. (Dale Watson)

June 15th, 2007, 11:25 AM	#4 (permalink)
11 Gauge Friend of Leo's Join Date: Mar 2003 Location: The East Coast Posts: 2,593 14 Photos	Tone stack bypass switch. __________________

June 15th, 2007, 02:23 PM	#8 (permalink)
jjmantele Tele-Holic Join Date: Aug 2003 Location: New Jersey Posts: 822	I used mine to install a female stereo 1/4" jack. It's wired to the cathodes of the power tubes on which have 1ohm resistors inserted to ground. I can insert a male stereo jack in it and connect my volt meter to measure/set bias, w/o pulling the chassis. __________________ JJman If it says "Vintage" on it -it isn't.

June 15th, 2007, 05:33 PM	#10 (permalink)
LPBlue Tele-Meister Join Date: Jul 2003 Location: Markdale Ontario...oot in the woods Age: 52 Posts: 263	How about a pentode/triode switch for a 1/2 power option? __________________ It didn't make that smell when it was new, PULL THE PLUG!

June 15th, 2007, 05:32 AM	#2 (permalink)
mr_hankey Tele-Meister Join Date: Sep 2005 Location: Netherlands Age: 19 Posts: 236	I'd go for a NFB pot.

June 15th, 2007, 11:28 AM	#5 (permalink)
Wally Friend of Leo's Join Date: Mar 2003 Location: Lubbock, TX Posts: 3,444	+2 on the NFB.

June 15th, 2007, 11:33 AM	#6 (permalink)
PhatTele Tele-Holic Join Date: Jun 2003 Location: Richmond, VA Posts: 663	Mid-range pot. Use a 25K audio taper. Attach the 6.8K resister from the Bass pot to the middle lug of the midrange pot. Ground the other end to the casing. Run a lead from the Bass pot (where the resister had been located) to the left lug of the midrange pot (looking at the back with the lug pointed up). On zero or one, the tone is "stock." Anything above stock is adding midrange. It's a nice mod which gives you a nice bluesy crunch without giving up the stock tone. Note: If you run the lead to the ground switch jack, you might need a shielded cable. Sometimes you might get a little feedback (not always) if you run the lead unshielded. If you put the midrange control in place of the second output jack, you typically don't need the shielded cable.

June 15th, 2007, 05:38 PM	#11 (permalink)
Ben Harmless Friend of Leo's Join Date: Mar 2003 Location: Albany, NY US of A Posts: 2,922	Install a "destroy all humans" switch. Seriously. If you like the amp, don't mess with it. Plus, while all those mods might be easy to wire up, unless you or a tech looks very carefully at getting the lead dress right, you're opening up a whole can of man-eating worms - seeing as how that hole is probably right next to the power tranny... NFB/presence prolly wouldn't be too bad, but a mid knob might be a problem, and a channel-jump switch would almost certainly be a nightmare. Now I'm absolutely going to put a "destroy all humans" switch on my next amp. __________________ "I think I'll go for the life of sin, followed by the last-minute, presto-change-o, deathbed repentance." - B. Simpson

June 15th, 2007, 05:59 PM	#12 (permalink)
dibber124 Tele-Afflicted Join Date: Dec 2006 Location: Long Island, New York Age: 53 Posts: 1,167	I like the NFB Switch. Back in the early'70s we called it the "Clapton Switch"! __________________ "I feel that it is healthier to look out at the world through a window than through a mirror. Otherwise, all you see is yourself and whatever is behind you." - Bill Withers

June 16th, 2007, 06:26 AM	#14 (permalink)
quackerz Tele-Holic Join Date: Sep 2006 Location: New Jersey Age: 45 Posts: 921 8 Photos	Well, maybe I'm getting old then. I just re-tubed and biased the thing, and holy crap! It sounds way better even with the original Oxford than my '64 no-logo ever did. Then again, I knew nothing about amps when I owned the '64 and did nothing except replace the power tubes when they failed. Bias pot? I turned it until it sounded good without smoke and flame. Maybe that's why I went through a lot of power tubes... Hahahaha! I'm gonna do the bias test point thingy. No sense making a great amp sound like something it's not. So how do you read plate voltage without pulling the chassis? The "Destroy all Humans" switch is still VERY enticing. Thanks for that, Ben!

June 17th, 2007, 03:10 PM	#16 (permalink)
quackerz Tele-Holic Join Date: Sep 2006 Location: New Jersey Age: 45 Posts: 921 8 Photos	Thanks, gotcha. But even though I work in IT, I suck at Excel macros. I was considering mounting two plate voltage test points on a plate that would cover the accessory receptacle socket but I completely chickened out. I ended up leaving all as is with the exception of installing an 18" male power receptacle cord and leaving my 1 ohm resistors in there. I wanted more play time on Fathers Day.