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PostPosted: Tue Dec 14, 2010 1:55 pm 
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Location: Urbana, IL
So, I finished my confidence boost and it did the trick: I want to start on the chorus kit. However, I want to build it for bass and I'm not sure what needs to change. Has anyone built a chorus v1.1 for bass? If so, can you list what needs to be changed? The few threads I've seen about this were apparently for an older version of the pedal. Thanks in advance.


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PostPosted: Thu Dec 16, 2010 12:10 pm 
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So last night I decided to see if I could figure this out on my own.

I found a site that had the BOSS CE-2 and CE-2B schematics, which just so happened to list the difference between the schematics. I sat down with these schematics, the list of changes and the chorus schematic and started looking at things.

Everything matched up well enough. I found that C12 in the BYOC circuit has the guitar value but has the bass value (.01uf) listed in parens. Nifty. There's the "extra included for bass mod" cap listed in the directions. R19 was a bit interesting; in both the BOSS schematics the value of the equivalent part (R22) is listed as 47k. In the CE-2B schematic there is a 250k pot in serial to the 47k resistor. R19 on the BYOC schematic is 33k. Looking at the circuit design, this 33k value would let a larger amount of the "wet" signal into the inverting amplifier. This seems like a good change to me. It's nice they have the 47k value listed for R19 in parentheses.

So, if I want to make thing work better for bass, I need to replace C12 with the .01uf cap. I'm guessing this changes the floor of the bandpass filter to allow for only applying the chorus effect to higher frequencies instead of the lower frequencies.

I got to thinking about the in-line 250k pot on the CE-2B. This pot basically appears to allow control over the wet/dry signal mix. If I wanted to have the same options as a CE-2B on my BYOC bass chorus I could just in-line a 250k pot with R19. This seems like a good idea to me, so I'm going to start shopping for 250k pots. My only concern is how to make the pot fit in the enclosure.

Disclaimer: I am not an electrical engineer. I've never even so much as looked closely at schematics before. I spent a few hours digging into this and talking with an EE friend of mine.

Am I doing this right? :)


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PostPosted: Thu Dec 16, 2010 10:56 pm 
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So, after looking at the CE-2B schematic again I noticed that the mix pot is a C pot...Everything else is listed as 100KB while the mix pot is listed as 250KC. I guess I'll be going with a reverse log pot, then. Hopefully I can find one that uses the same shaft type/diameter as the pots I got with my kit.


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PostPosted: Mon Dec 20, 2010 2:10 pm 
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So I'm going to use a b250k pot for the mix control. I don't care if the original was a c250k, which isn't certain. Waiting for parts to arrive.


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PostPosted: Wed Dec 29, 2010 2:38 pm 
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Hi there - nobody seems to take any interest in your post?! I for one feel that it's highly interesting. Pls. let us know about the results of your mods and especially the wet-dry-pot. If it works fine, I'd appreciate a detailed intstruction!


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PostPosted: Wed Dec 29, 2010 2:56 pm 
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Hi joerch,

Welcome to the BYOC forums.

If this all works, I'll post instructions on how to add the third pot. It amounts to sticking a b250k pot somewhere in the case, soldering two of the lugs together and in-lining a resistor back to the spot where the old resistor was.

I've got everything I need to finish the work, but haven't had the time. I'll hopefully have it done within the next few weeks.


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PostPosted: Sun Feb 20, 2011 11:47 pm 
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So I figured I should update my thread here in case someone else comes looking for this info. The wet/dry mod is not just a bass mod, but it's patterned after the 'E-LEVEL' knob on the BOSS CE-2B, so I'm posting it here anyway.

The cap swap was trivial. The kit comes with the cap.

I used a B250k pot. The original circuit diagram has the pot as a C250k, but...I just don't care. I didn't see the point of the reverse-log pot. I soldered a jumper between the wiper and the left ("cold" in this case) lug and hung a resistor off the right ("hot" in this case) lug, like so:

Image

Then I ran wires to the right places relative to R19. Note that you're running wires to the back side of the board and soldering on the component side.

Image

I had already drilled a hole in the enclosure below the LED location and spaced it out from the LED about the same distance as the other two knobs were, just to keep things nice and even. You can see the relative position of the mix pot in the next pic. Note that I decided to not have the leads crossing tightly since they reverse position once you swing the pot around, so be careful.

Image

People have been asking me why I shorted the cold and wiper leads together. In this particular circuit you could probably get away with not doing so, but I generally try to follow best practices. There's a few reasons for the jumper. The first makes the pot a bit more "fail-safe." Pots usually fail due to the wiper losing contact with the disc inside the pot. If you just run a wire from the wiper and the hot lug without shorting the wiper to the cold, the pot will fail "open." With the wiper and cold lugs jumpered together, the pot will fail to its maximum value, in this case 250k. Again, it's not a big deal in this circuit, but knowing which way something will fail and which way will least adversely affect your circuit is a good idea. A few other reasons mentioned to me by some electrical-engineering friends of mine were to mitigate charge differences in the pot and to mitigate any ground issues that pop up...Again, not a big deal in this circuit, but just to be safe I took the minute and made the jumper.

Hope this helps someone...


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PostPosted: Sun Dec 11, 2011 2:13 am 
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Is there any reason I couldn't /shouldn't add a switch to change c12's capaticor back and forth between the bass and guitar value?


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PostPosted: Sun Dec 11, 2011 3:32 am 
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No. :) I considered doing the same thing for my pedal but just went with the bass-value cap. Should be quite straightforward to do.


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PostPosted: Sun Dec 11, 2011 1:22 pm 
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Sweet, I'm excited for the kit to come!

Sorry, I know I am a bit of a nube...


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PostPosted: Sun Dec 11, 2011 4:32 pm 
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Nothing to apologize for; I'm still surprised my pedal works at all. This was the first (and so far only) pedal I've built.


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PostPosted: Sun Mar 11, 2012 9:14 am 
A reverse log or anti-log pot in that position is likely to give you a smoother control over the mix.

With a linear pot you are likely to get not much happening over much of the controls rotation and then it will all happen at once. If you cannot get an anti-log pot you can use a log pot and wire it and use it in reverse. Some may tell you this does not work - that a log pot wired in reverse is not equivalent to an anti-log, but I can assure you it is and it does. The only drawback is having to remember the control operates counter clockwise.


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