Boss CH1 Super Chorus, Vibrato mod? Is there one?

[aarondavis]

Guy's, I have a Boss CH1 I'd like to add a switch for vibrato only mode.  Does anyone know how to do this. 

Forgive me, I'm not a DIY expert so be kind...

Please post pics, suggestions, warnings et al.  Thanks

[chassit]

http://www.erikhansen.net/?page_id=27

I just got a CH-1 yesterday that I was considering putting these mods into.

[Mark Hammer]

Keep in mind that about 97% of commercial chorus pedals do their "bypassing" by simply using a single FET to cancel the delay signal, leaving only the clean unaltered signal.  Vibrato, on the other hand, is produced by cancelling the clean signal and leaving only the delayed signal.  What this means is that if you install a toggle to lift/cancel the dry sigal in order to produce vibrato, when you step on the pedal to completely bypass the effect, you won't have ANY signal unless you also flip the toggle to restore the clean.  This may not be what you're looking for.

It IS possible to have an automatic flip-over, using an extra FET and a few additional parts, but the level of knowledge required to do that sort of a mod is a little more extensive than what is required to simply find a particular resistor, unsolder one end, and run a pair of wires from there to a toggle.  Not impossible, mind you, but if you are asking how to do a basic vibrato mod here, that would suggest that you're on Chapter 2.  Doing a vibrato flip-over, using FET switching, is more like Chapter 4 or 5.

So, if you can bear to have the pedal be NOT gig-ready, then by all means go ahead, and use it in the best of health.  If you need it to go from vibrato to bypass for gigging purposes, you may want to reconsider for the moment.

[aarondavis]

Thanks Mark for the quality info.  You're exactly right, I'm still reading Chapter 2....

The purpose would be to maintain the pedal in gigable condition, since that's mainly what I do.  It's just that after a few other mods I've done to the CH1 it's a pretty good pedal now; so I wanted to see if I could get a vibrato effect from it. 

I've also thought about purchasing the Analog Chorus kit from BYOC and putting the Vibrato switch in. That pedal in Chorus mode my even be a better sound anyway.  What do you guy's think? 

[Mark Hammer]

If it's a pedal with true bypass, then whatever you do to get vibrato will have no effect on the bypass sigal.  The problem I described earlier only occurs when you use FET switching in a particular way.

I don't want to embark on, or initiate, a whole discussion on the relative merits of attempting to convert a FET-switched pedal to true bypass.  I'll simply say that:
a) if you have some extra money that you don't mind dropping,
b) if you are up for the learning experience of building a complete pedal from scratch,

...then what you suggest is a fine solution to your needs.  Besides, if chorus PLUS vibrato has been good enough for Adrian Belew, then it ought to be good enough for you too, right?

[vanhansen]

Or, just insert a 1/4" plug not going to anything in to Output B.  You'll get the effect only signal when the effect is engaged and the clean signal when bypassed.

[Mark Hammer]

Clever!  My hat is tipped in your direction, sir.

[aarondavis]

Yeah, I've built a half a dozen BYOCs.  I know many here would prefer that I spend the time and research to build one from scratch.  But BYOC kits are worth the premium to me to not do the leg work in sourcing all the parts.  It's still quite rewarding to put a pedal together and it sound as good as the majority of the boutique stuff out there.  My Ross Compressor that cost me about $85 bucks to complete is as perfect as a compressor can get IMO.  

Thank you guy's so much for your kind comments and information.  

[aarondavis]

Hum, so I could still add a mini switch to the effect and get my desired result.  What about simply changing the pedal to a mono only jack?  I don't use it stereo anyway...

If so, I'm still going to need to do some reasearch on how to do the switch.  But its cool the possiblity is there. 

[vanhansen]

Clever!  My hat is tipped in your direction, sir.

You gave me that idea a couple years ago. But thanks. 

[chassit]

I'm very new at this, so correct me if I'm wrong. If you can toggle this effect by putting a mono plug into the stereo jack of output B couldn't you just put a SPDT switch that will ground the connection that would normally go to the sleeve of the plug?

[Mark Hammer]

The CH-1 has two output jacks.  The intent is to provide one kind of "normal" output signal when only one jack is used, but a different kind when 2 jacks are used.  The change in the status of output jack 1 is enabled by insertion of a plug into output jack 2. I won't say it is entirely unique to the CH-1, but I will say that having 2 output jacks on a chorus is not always a surefire guarantee that this arrangement has been implemented on a pedal.

[chassit]

The CH-1 has two output jacks.  The intent is to provide one kind of "normal" output signal when only one jack is used, but a different kind when 2 jacks are used.  The change in the status of output jack 1 is enabled by insertion of a plug into output jack 2.

Right I understand that. I was asking if this switch could mimic putting a plug (not connected to anything) into output B to cause this change in output A status. Like this.

[Mark Hammer]

From the looks of it ( http://www.schematicheaven.com/effects/boss_ch1_superchorus.pdf ), yes.

[chassit]

Just wanted to update: I made this mod but actually used a spst switch to ground the connection in the on position rather than having the normal signal have to go through the switch when off. It works just fine.

[Mark Hammer]

Thanks for that update.  Posting followup is every bit as important as the great idea around here.  Much appreciated.

[chassit]

It's been a long time since I've had time to mess with this stuff, due to being insanely busy with school. But I made further modded this pedal way back in August and never remembered to put a picture up until now. I included 2 of Mark Hammer's mods as found on Eric Hansen's site. http://www.erikhansen.net/?page_id=27 However, I made both mods switchable.
 

For the Chorus/Vibrato, all I had to do was place a SPST switch to ground the the sleeve connection of the output B jack.
I'd also like to thank Mark Hammer for his feedback on another thread that confirmed my logic in doing it this way. http://www.diystompboxes.com/smfforum/index.php?topic=70064.msg564178#msg564178

[ashcat_lt]

For the Chorus/Vibrato, all I had to do was place a SPST switch to ground the the sleeve connection of the output B jack.

This is a super old thread, but I was searching for insight into my dilemma and stumbled across this, and felt like being that guy.   

The Sleeve of output B is grounded.  It's the Ring that needs to be switched.

My thing had to do with sticking a TRS>XLR cable into that hole on my bassist's pedal and connecting it to a balanced mic pre.  It seemed the other night that this was causing the output A signal to lose an inordinate amount of volume, and I was looking at schematics trying to figure out why this might be.  Was looking at the right side of the schematic and trying to work out that transistor switchery that happens there and thinking maybe the fact that there was ~1k resistance where it expected a straight wire...

...then I followed that back a little ways and saw the E. LVL pot...   

[mimmotronics]

Reviving this because I'm in the same boat and am trying to accomplish this mod without having to work around the output B jack...

My suspision is this is simply a logic problem, I just need to find what type of logic gate I need and build it with transistors while using the correct input/output connections.

After writing it out on a bunch of scraps I've concluded what's needed is a NAND with inputs A and B, output Z:
Input A = Effect ON/OFF
Input B = Vibrato Mode ON/OFF
Output Z = Signal to switch on the FET responsible for the dry signal

Truth Table:
A.    B.     Z.   
0.     0.     1.
0.     1.     1.
1.     0.     1.
1.     1.     0.

In the process of breadboarding, should be back sometime during the week for updates...

[mimmotronics]

So I've successfully pulled this mod off via breadboard using a CD4011 quad NAND-gate IC package. The A input (vibrato mode toggle) is implemented using a simple SPDT switch. The B input (bypass toggle) is pulled from the base of transistor Q4. The output of the NAND gate Q is fed to the gate terminal of the JFET, Q1, which is responsible for the dry signal.

This works, I only need to figure out how to practically implement it... I'd rather use a smaller IC chip, so I'm thinking this 2-input Dual NAND package will do.