smid
Joined: Jan 30, 2016
Posts: 33
Nuremberg
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Posted on Dec 01 2016 03:07 AM
Hi.
This short article describes an easy way to tweak the sound of your reverb in the high-mid range. The method is not new and is described in several tube-related forums. Also some Fender amps have it partially built in.
I implemented it in my Surfy-Bear-Reverb and a short discussion with Björn encouraged me, to post it here.
You can apply the method with any device that uses a "pan" to produce the reverb (Surfy-Bear, Fender 6G15, Fender Reverb Amp etc.).
Technically you simply add a small capacitor between the output of the pan and ground. That's it. Technically spoken, the cap will shift the resonant frequency of the pan. It is similar to the so called "C-Switch"-mod for electric guitars.
In my projects I used a rotary switch with 6 positions to select between different capacitor values. So I have the possibility to change values on the fly. I wired the switch with the following cap-values: none, 2.2n, 4.7n, 5.6n, 6.8n, 8.2n. Values above 8.2n may result in kind of annoying, whistling formant.
The results can be heard in a short .mp3, the cap-values are announced before switching takes place.
reverb-color-switch
The sound example is a Surfy-Bear with a new accoutronics pan, Stratocaster witch Pickup 1+3 in series and the dry-channel of a SF Fender Bandmaster.
Andreas
— see you at monokinibeach
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Ariel
Joined: Aug 29, 2009
Posts: 1556
Israel
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Posted on Dec 01 2016 06:04 AM
Interesting!
So, what it does is shift the high-mid peak?
Instinctively, I would also wire a bypass position too, just to have the original sound.
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smid
Joined: Jan 30, 2016
Posts: 33
Nuremberg
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Posted on Dec 01 2016 06:42 AM
Yes,it shifts the high-mid peak.
The "bypass" position on my rotary-swicht is what I mentioned as "none". In that position there is simply nothing between the pins of the switch, so the original circuit is unaffected. To connect the pins directly with a jumper wire (as one would do to bypass e.g. an effect) would result in shortening the reverb-signal to ground. I guess you wouldn't want to do this 
Andreas
— see you at monokinibeach
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Badger
Joined: Nov 16, 2013
Posts: 4536
Wisconsin
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Posted on Dec 01 2016 06:56 AM
Andreas, this is very cool. It's a great extension (i.e., next level) of what Danny mentioned awhile back when he mentioned about the impact of treble on the overall sound, and this is applied after the tank so it is not feeding a "colored" signal into the tank. Even if one is after the same "apparent" tone, one could alter the tank to accomodate constraints of mic, room, venue, other instruments & other acoustics with what is a very portable reverb tank. Very versatile mod.
I wonder how this would fare with the MOD pan, with its well-known deeper tail, for those Surfy Bear builders out there who used that one.
— Wes
SoCal ex-pat with a snow shovel
DISCLAIMER: The above is opinion/suggestion only & should not be used for mission planning/navigation, tweaking of instruments, beverage selection, or wardrobe choices.
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Ariel
Joined: Aug 29, 2009
Posts: 1556
Israel
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Posted on Dec 01 2016 07:25 AM
smid wrote:
The "bypass" position on my rotary-swicht is what I mentioned as "none".
Sorry somehow I missed that. Perfect.
Excellent mod! I'm going to do it.
Badger wrote:
I wonder how this would fare with the MOD pan, with its well-known deeper tail, for those Surfy Bear builders out there who used that one.
Most probable.
The MOD has a long tail and a kinda 'honky' character. I guess it will help taking care of the latter.
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smid
Joined: Jan 30, 2016
Posts: 33
Nuremberg
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Posted on Dec 01 2016 08:11 AM
One could do a switch-position with a jumper wire between the pins to accomplish a "rev-off" position, in case you forgot the footswitch at home..... In fact this would behave exactly like the rev-foot-switch's function.
The circuit below is from the Silverface-Ultralinear-Mastervolume-ProReverb. You see that fender here also used a 2.2n (equals 0.002u) cap to freshen up the rev-sound. Also you see the foot-switch to shorten the rev-signal to ground (switch off the reverb).
Edit: The 220k resistor in parallel to the 2.2n cap is the grid-leak-resistor of the rev-recovery tube and doesn't have anything to do with the "color"-cap.
Andreas
— see you at monokinibeach
Last edited: Dec 01, 2016 08:14:50
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SandBug
Joined: Feb 22, 2016
Posts: 442
California
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Posted on Dec 01 2016 03:08 PM
Thanks for sharing. Too cool!! I'm definitely doing this superb mod on the next two units i'm making. The audio samples sound great!
Last edited: Dec 01, 2016 15:13:21
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bjoish
Joined: Jul 06, 2010
Posts: 596
Stockholm
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Posted on Dec 02 2016 08:58 AM
Yes, very cool mod, Andreas!
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warioblast
Joined: Nov 23, 2014
Posts: 98
Dijon
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Posted on Dec 02 2016 06:03 PM
It sounds like a worthy addition. Thx 
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SandBug
Joined: Feb 22, 2016
Posts: 442
California
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Posted on Dec 16 2016 10:44 PM
The Surfy Bear with the color switch is awesome! Just finished the modification yesterday. Love it.
Thanks to Andreas and Bjorn for sharing these great things.
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smid
Joined: Jan 30, 2016
Posts: 33
Nuremberg
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Posted on Dec 17 2016 06:29 AM
Great to see that someone could make use of it! How did you find the knob with the triangle instead of the numbers? Looks perfect!
Just curious: which cap value do you personally like best with your pan, and which pan do you use?
Andreas
— see you at monokinibeach
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Badger
Joined: Nov 16, 2013
Posts: 4536
Wisconsin
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Posted on Dec 17 2016 07:52 AM
SandBug wrote:
The Surfy Bear with the color switch is awesome! Just finished the modification yesterday.
Holy krap! Is that a toolbox? You could cruise that on Van Nuys Blvd on Wednesday nights. NICELY done!
— Wes
SoCal ex-pat with a snow shovel
DISCLAIMER: The above is opinion/suggestion only & should not be used for mission planning/navigation, tweaking of instruments, beverage selection, or wardrobe choices.
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wfoguy
Joined: Dec 11, 2011
Posts: 2118
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Posted on Dec 17 2016 09:23 AM
For those of us that don't want to screw up, can you post a simple drawing showing where to split and where to end up? 
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SandBug
Joined: Feb 22, 2016
Posts: 442
California
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Posted on Dec 17 2016 09:37 AM
Thanks, Badger! Love that description. I try. And thanks, Andreas! I was lucky to find that knob in my toolbox, but i originally got it on a used Univox Hi flier purchased in the 90's. Wish I had more of them. I assume it was an odd replacement knob the store just stuck on there.
I really dig the 6.8nf cap, but I must say I like them all. I often have dwell up and mix down and the caps work very well to emphasise the squinky/splashy drip that made me want a Surfy Bear Reverb in the first place.
This mod is great for cleaning up tones, but also great for getting on the noisy side, just depends how it's used. Also great for having several different reverb tones when I'm recording multiple guitar parts. It's a very useful and versatile mod.
I've used new Accutronics pans on all 5 of my Surfy Bear builds, and been happy with them.
wfoguy, no problem, once i get home from work I'll post any info thats not already answered. And I used a two pole six position rotary switch.
Last edited: Dec 17, 2016 18:23:49
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smid
Joined: Jan 30, 2016
Posts: 33
Nuremberg
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Posted on Dec 17 2016 09:41 AM
You don't have to split or clip anything in your existing wiring. Simply add the capacitor (or the switch) between the exit of your pan and ground. The easiest point to do this is exactly where SandBug did it: at the solder-side of the RCA-Socket. One leg of the cap (or the switch) to the central stud (together with the signal carrying wire, normally "red"), the other leg to the washer-lug (together with the ground wire, normally "black").
Does that help?
Andreas
— see you at monokinibeach
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wfoguy
Joined: Dec 11, 2011
Posts: 2118
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Posted on Dec 17 2016 10:14 AM
Yes, thank you. Do you have a description of the rotary switch to aid in googling?
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smid
Joined: Jan 30, 2016
Posts: 33
Nuremberg
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Posted on Dec 17 2016 11:40 AM
I use this one, 2 poles, 6 positions:
manufacturers website
SandBug might know an US reseller, it looks like he used the same rotars-switch.
Andreas
— see you at monokinibeach
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SandBug
Joined: Feb 22, 2016
Posts: 442
California
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Posted on Dec 17 2016 06:18 PM
smid wrote:
SandBug might know an US reseller, it looks like he used the same rotars-switch.
I got mine from ebay, and i've read that Radioshack may carry it at some locations.
Last edited: Dec 17, 2016 18:20:16
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Latherman87
Joined: Dec 20, 2012
Posts: 178
Oklahoma
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Posted on Dec 18 2016 08:24 AM
Would one be able to do this with an on/off toggle? I love the 8.2....so I'd like to be able to simply switch between no cap and the 8.2 to get just one more level of verb....or would I have to use an on/off/on toggle? I have limited electronics knowledge so any dumbing down for me is greatly appreciated. I'm not quite sure.thanks!
— If you want the ultimate,you gotta be willing to pay the ultimate price.
Brett
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smid
Joined: Jan 30, 2016
Posts: 33
Nuremberg
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Posted on Dec 18 2016 10:02 AM
Sure!
Andreas
— see you at monokinibeach
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