Thursday, June 5, 2014

Development and custom builds

 At the moment I am working on a few custom builds and because of specific customers wishes I have been trying out some new things with circuits and enclosure finishing. 

R E L A Y  S W I T C H I N G

I wanted to get rid of 3PDT switches with their loud clicks and unreliability and move to a momentary switch/relay system. Momentary switches have less moving parts which means there is less chance they will fail and there are a lot more types of these to choose from. Depending on the type of momentary switch they can also be a lot more quiet and easier to press. Having relays is more reliable than a 3PDT and it offers the freedom of controlling several relays under one switch, which makes it possible to have stereo true-bypass along with LED indication.

My first experiment involved making my own relay controller IC plug-ins. The Flip-Flop circuit of the FET bypass used in Boss and Ibanez pedals can be used to control a latching relay and LED using a momentary switch.
I split the circuit across 2 little veroboards and connected them to each other and a 14 IC-socket after which I immersed it in epoxy resin.
The idea was to make builds really quick, easy and small, but building the tiny 3-D circuit took me a whole afternoon and a lot of headaches, so it proved to be more expensive in the long run than building the whole CMOS relay circuits I am using now.

T E N - C H A N N E L  B Y P A S S - L O O P E R

 One project I am currently working on will be a 10 channel bypass looper. This project was the main reason for finding a simple and affordable relay switching system, as space is limited and having 10 switches the costs add up quickly. I took the same approach to the buffer and mixing circuits for the very same reason and decided on a FET buffer/blender with phase correction. It is a circuit with very few parts and allows to correct the phase on pedals that reverse it, because when blending in an opposite clean signal will cause phase cancellations causing for instance in my delay for the first attack to completely disappear and only hearing the repeats.

Buffer/Mixer prototype with the CMOS relay circuit.
The prototype worked great and made a few of my digital (multi) effects useable again. By blending in a buffered analog signal, the sounds retained the direct feel and dynamics I found I otherwise lost with digital pedals.

It will have 5 mono channels, a mono send/stereo return channel, then 2 mono channels that can be switched to either to the left or right,  2 stereo in/stereo out channels and 10x9V, 2x18V and 2x24V DC outputs. It also has a master bypass and master wet/dry mix which can be operated by an expression pedal.
Each channel will have a 3 way rotary knob that selects between buffer/mixer bypass, 0 degrees phased and 180 degrees phased buffer. This this avoids any phase reversal issues, no matter which or how many bypass channels are selected.
There will be light from blue LED's coming out of the sides of the enclosure,  along with red LED's that are responding to volume changes. So the blue light will become purple-ish when you hit the strings and when using a stereo pedal like a ping-pong delay you will also see the purple light bounce left to right.

S T E R E O  V I B E S

600p sanded on the right, 800p sanded and polished at the left
A customer asked for a Stereo Vibe in a blue wah enclosure with a chrome threadle, like my prototype stereo liquivibe. The chroming proved incredibly expensive so I tried a different brand of polish, hoping I could get the threadle as shiny as a chromed one, and so far I'm very pleased with the result.

Custom Stereo Vibe 002 and 003

For the enclosure I decided on trying a classic surf green nitrocellulose finish. At the moment it doesn't seem as blue as the examples of old stratocasters and chevy's I found, but I will have to wait and see how it will look after the last clear-coats and polishing.

I redesigned the layout because of the added stereo circuitry, moved to whole board closer to the back and moved the light-shield forward on the board for better clearance with the bottom-plate.

I will go into more detail in the next post about the Custom Stereo Vibe 001 I just finished, which apart from being in a 1590D enclosure shares the exact same circuit.

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