Bronx Cheer with 4066 switching

[sweetwilly]

Hey hey - after several years in the wilderness (well, boxed up in my cupboard to be more precise) my little workshop is back in action.  I'd built everything I needed, and concentrated on playing for a while, but now I'm in a "psych" band again, and have been buying more amps, I need new toys and boy has the bug bitten again.

I thought I'd post this Bronx Cheer after some success with electronic switching.  Thanks to RG's article here - http://www.geofex.com/article_folders/cd4053/cd4053.htm and The Tone God's Wicked Switch article here - http://tech.thetonegod.com/switches/switches.html.

After struggling to beat a noisy switch on my all time favourite dirt box, my beloved Guv'nor copy, I started playing around with electronic bypasses.  I managed to tame the noise on the Guv'nor using the 4053 design from GEOFEX, but still had a slight pop - this was a massive improvement over the clunk I was getting so put it down as a win and moved on.  I then built a Centaur clone using an Aion Electronics PCB and realised I could adapt the Wicked Switch to the Centaur's bypass scheme and gave it a whirl.  Hey presto - just like magic - no appreciable switching noise and I was able to use an illuminated arcade push button as the footswitch - no stomping, but none required.

Moving on, I'd breadboarded the Bronx Cheer and loved the glitchy synth feel of it.  I'd also come to realise I needed a buffer at the end of my chain due to a change of the lineup, so I decided to kill two birds with one stone and build a buffered Bronx Cheer.  It's a mash up of the Wicked Switch, the Centaur's bypassing scheme, the IC buffer from General Guitar Gadgets and the Bronx Cheer circuit.  Problem solved.

Here's the layout, BOM and some pics - I'll do a sound clip shortly.  Please note - I haven't used DIYLC for many,many years, so probably could have done a better job of it, but this was mainly for me to use while building and did the job.  Also, no real theory to the design - just grabbed bits that worked elsewhere and jammed them together - there's probably a ton of refinements to be made here, but as I said, seems to be doing the trick.

Layout - I forgot to label the LED + - It's the brown jumper - B P - the arcade switches have limiting resistors built in, so one will need to be added for regular LEDs.



Build

[GiovannyS10]

Wow! One day i really want to be too much courageous to try this 4053/4066 or other CI bypass. For me, by now the problem is i think the arcade button can be unstable to use live, no? Maybe too much slippery? Or easy to break when we use the feet to press it down? Hahaha. I don't know i have some questions about this but about your project, OMG seems incredible. Are you using the transformer only like a simple inductor?

[amptramp]

It is possible to build a switch from a CD4007UB.  Since there is no buffer between the gate inputs and the gating transistors, you can use an R-C filter on the pin 3 and pin 10 gate inputs to make the switchover gradual and avoid switch pops entirely.  Check Figure 1 here:

http://pdf1.alldatasheet.com/datasheet-pdf/view/174180/ONSEMI/MC14007UB.html

It is also possible to use diode bridge gates if you can control the impedances so the diode resistance doesn't matter.  A lot of FM multiplex adaptors used diode switching where the diodes are reverse biased or forward biased to conduct or block signals.  There are a number of ways that have been used but I concur with sweetwilly in that the standard 3PDT switch is a major reliability hazard in most designs.  Boss and Ibanez also concur.

[sweetwilly]

Wow! One day i really want to be too much courageous to try this 4053/4066 or other CI bypass. For me, by now the problem is i think the arcade button can be unstable to use live, no? Maybe too much slippery? Or easy to break when we use the feet to press it down? Hahaha. I don't know i have some questions about this but about your project, OMG seems incredible. Are you using the transformer only like a simple inductor?

Thanks Giovanny, yes, the arcade button may not be the most reliable switch, but looks cool and only need the lightest touch. I probably wouldn't use them if the pedal was for someone else, but I have a bunch (got 10 for just under AU$20 from Taiwan) and a 2min replacement job, so worst case I go half a set without being able to use the Bronx Cheer part of the circuit, but the buffer would still be on.

I'd encourage you to have a go. Endless hours of breadboard fun and great info from RG Keen & The Tone God in the links above.

The transformer simulates a guitar pickup so the circuit works correctly - http://www.muzique.com/lab/pickups.htm. The original schematic for the Bronx Cheer states it can be left out if NO buffer before it - http://www.diale.org/escobedo.html.


Sent from my iPhone using Tapatalk

[sweetwilly]

It is possible to build a switch from a CD4007UB.  Since there is no buffer between the gate inputs and the gating transistors, you can use an R-C filter on the pin 3 and pin 10 gate inputs to make the switchover gradual and avoid switch pops entirely.  Check Figure 1 here:

http://pdf1.alldatasheet.com/datasheet-pdf/view/174180/ONSEMI/MC14007UB.html

It is also possible to use diode bridge gates if you can control the impedances so the diode resistance doesn't matter.  A lot of FM multiplex adaptors used diode switching where the diodes are reverse biased or forward biased to conduct or block signals.  There are a number of ways that have been used but I concur with sweetwilly in that the standard 3PDT switch is a major reliability hazard in most designs.  Boss and Ibanez also concur.

Thanks Amptramp - I'll have a look at that later. I'm really happy with the 4066 & buffer design as per the Klon Centaur. Not 100% sure what the 68k resistors do, but it's worked out well in my Centaur clone and this build, so until it doesn't work I'll probably stick with it.


Sent from my iPhone using Tapatalk

[sweetwilly]

UPDATE - while recording sound clips I noticed the effect bleeds through when bypassed if the volume is above 9 o'clock.  Think I need to use the other side of the "DPDT" switch to ground the effect when bypassed.  I seem to recall it being on the breadboard, but somehow missed it when doing up the layout and check.  Should be an easy fix...  (famous last words).

[sweetwilly]

FIX - Put an electro (I tried 2.2uf, 4.7uf and didn't notice much difference) in the bottom right corner and run jumper from negative to Pin 4 on the 4066 and a jumper to the circuit side of C10.  Slight (very slight) switch pop, but that could be down to the arcade button.  Still looks cool!

[duck_arse]

sweet - welcome back. it's nice to see another cobber "at it".

Hey hey - after several years in the wilderness (well, boxed up in my cupboard to be more precise) my little workshop is back in action.  I'd built everything I needed, and concentrated on playing for a while, but now I'm in a "psych" band again, and have been buying more amps, I need new toys and boy has the bug bitten again.

[sweetwilly]

sweet - welcome back. it's nice to see another cobber "at it".

Hey hey - after several years in the wilderness (well, boxed up in my cupboard to be more precise) my little workshop is back in action.  I'd built everything I needed, and concentrated on playing for a while, but now I'm in a "psych" band again, and have been buying more amps, I need new toys and boy has the bug bitten again.

Cheers mate!


Sent from my iPhone using Tapatalk

[GiovannyS10]

Thanks Giovanny, yes, the arcade button may not be the most reliable switch, but looks cool and only need the lightest touch. I probably wouldn't use them if the pedal was for someone else, but I have a bunch (got 10 for just under AU$20 from Taiwan) and a 2min replacement job, so worst case I go half a set without being able to use the Bronx Cheer part of the circuit, but the buffer would still be on.

I'd encourage you to have a go. Endless hours of breadboard fun and great info from RG Keen & The Tone God in the links above.

The transformer simulates a guitar pickup so the circuit works correctly - http://www.muzique.com/lab/pickups.htm. The original schematic for the Bronx Cheer states it can be left out if NO buffer before it - http://www.diale.org/escobedo.html.


Sent from my iPhone using Tapatalk

Hi sweetwilly,
Not understand wrong, i loved your idea! Maybe i will use the same arcade button when i build my own guitar synth pedal...  8/16 bits sound with a pixel art enclosure Hahaha. But it's an idea for the next year.
I will check out your links, i already built pedals using this kind of transformer but only cloning, i am not sure how it works, but i think your links will help me. Thank you a lot. Have soundclip?

[sweetwilly]

Thanks Giovanny, yes, the arcade button may not be the most reliable switch, but looks cool and only need the lightest touch. I probably wouldn't use them if the pedal was for someone else, but I have a bunch (got 10 for just under AU$20 from Taiwan) and a 2min replacement job, so worst case I go half a set without being able to use the Bronx Cheer part of the circuit, but the buffer would still be on.

I'd encourage you to have a go. Endless hours of breadboard fun and great info from RG Keen & The Tone God in the links above.

The transformer simulates a guitar pickup so the circuit works correctly - http://www.muzique.com/lab/pickups.htm. The original schematic for the Bronx Cheer states it can be left out if NO buffer before it - http://www.diale.org/escobedo.html.


Sent from my iPhone using Tapatalk

Hi sweetwilly,
Not understand wrong, i loved your idea! Maybe i will use the same arcade button when i build my own guitar synth pedal...  8/16 bits sound with a pixel art enclosure Hahaha. But it's an idea for the next year.
I will check out your links, i already built pedals using this kind of transformer but only cloning, i am not sure how it works, but i think your links will help me. Thank you a lot. Have soundclip?

All good Giovanny!  I only have a basic setup at home but will get a soundclip up over the weekend.

Here's the klone I built couple weeks ago. I used the Refractor PCB from Aion Electronics. https://vimeo.com/182944424


Sent from my iPhone using Tapatalk

[sweetwilly]

Here's a clip.

Gibson Firebird - Firebird Humbucker in neck and Lollar lapsteel single coil in bridge - both on into Ampeg Micro VR Bass Head into Garageband with no effects.  First bit is through a true bypass pedal, then the buffered bypass then (obviously) the effect.  I switch it on and off a few times so you can hear the switch noise (or lack of!) and change to high filter.  I (again, obviously!) do not use hammer ons, etc much - but you get the point...

Oh and don't have your volume up too much - level jumps a bit at 0:17!

http://www.aronnelson.com/DIYFiles/up/Buff_n_Bronx.mp3

[sweetwilly]

Thought the buffer sounded a bit thin, so upped the input cap to 220n.  Better.

Also, Pin 8 of the TL071 is not connected - I cut the pin off the socket to squeeze the layout a row tighter, but, again, forgot to label as such.   

[GiovannyS10]

Perfect dude! Be sure i liked a lot your project... Now i am diving in projects haha, but i will try your switch schematic as soon as possible, and of course will share with the community and with you 

[sweetwilly]

Thought the buffer sounded a bit thin, so upped the input cap to 220n.  Better.

Also, Pin 8 of the TL071 is not connected - I cut the pin off the socket to squeeze the layout a row tighter, but, again, forgot to label as such.   

Double  - I meant Pin 5!!  1 and 8 are pretty obviously not connected...