Jan172010

Kit building: Mod Amp Kits guitar reverb pedal

Published by paul at 5:11 PM under Kit Building | Audio

My 8-year old daughter started learning to play the electric guitar in September and that gave me an idea for one of the first kits to make to brush up my soldering skills. I'm using a Weller WD1001 soldering station which is light-years better than the old unregulated soldering irons I used to use 15 years ago in the UK. I made a couple of little light-following bugs (the MK129 and MK127 - the MK127 has much better movement) and then a reverb module from Build Your Own Clone (BYOC). It had a nice PCB but when I made it there was a weird short-circuit I couldn't figure out on Christmas Eve in time to wrap it up for a present the next day (all three pins of the 78L05 regulator gave 9v!!) so decided to try another brand.

I settled on the The Verb kit from Mod Amp Kits. It uses the Belton BTDR-1 DigiLog Reverb module (here's the PDF datasheet) and has a cool green box that my daughter thinks is groovy. The kit circuit is pretty simple but I'd failed to notice that it's not PCB based - it's all built using tag strips - aaarrgh! I find tag strips *really* annoying to solder on, and this kit is especially finicky as the instructions call for the tag strips to be mounted inside the box and then the components soldered in, however the instructions are excellent and everything went to plan - the kit is very well designed and I'd recommend it.

The following photos show the build process at various steps so anyone else building this can see what it's supposed to look like. Click the image for a 1024x768 blow-up.

1) Here are the contents of the kit. There's also a printed assembly manual and the case. The manual for this kit is much better than the BYOC kit.

 

2) End of Section 1 (Drawing 2 in the manual). Note that the footswitch must be mounted with the lugs horizontally, but it doesn't matter which way up. It's a 3PDT (three-pole, double-throw) switch. The BYOC kit didn't explain this, so I wasted a bunch of time figuring out how the switch worked. Notice how close the tag strips come to the input and output jacks. I had to do some tag bending to make sure there were no short-circuits. Everything's very close together, and the box gets very crowded (as we'll see below) so I wouldn't recommend this for soldering beginners.

 

3) End of Section 2 (Drawing 3 in the manual). I liked their idea to use sleeving from the hook-up wire to insulate the unused pins on the reverb module, but it left me a little short of wire in the final stage - luckily I had some of the same color and gauge lying around (couldn't possibly have multi-colored hook-up wire inside the box - very untidy :-)

  

4) End of Sections 3 (Drawing 4) and 4 (Drawing 5). Drawing 5 doesn't give a simple representation of the footswitch wiring. Pay attention to the last line of paragraph 3 in Section 3 - I misread and soldered it - and then had to unsolder again when I realized more wires would connect to log 3 of the pot.

 

5) End of Section 5 (Drawing 5). I ended up mounting the reverb module as soon as I could to get it out the way of everything else.

  

6) Working through Section 6 (Drawing 6). Although the soldering order given in the manual is pretty good, I found it better to slightly reorder how I did things for easier access to the terminals as I went along. I also worked out how to layer the components vertically so I could solder them individually rather than trying to have 4 components balanced inside the box an solder them all at once - almost impossible. Pay particular attention to the orientation of the two transistors - they're both soldered gate-source-drain left-to-right. The images show the progression through the terminal wiring. You can see a few little nicks in the insulation on two of the wires in the right-hand of the box - testament to how closely packed everything is.

  

 

7) End of sections 6 and 7 (Drawing 6). Not quite as tidy as the image on their website but I was very pleased with my handiwork!

 

8) The finished unit from the outside.

 

Total build time was around 6 hours. We tried it out last weekend and it worked perfectly first time!

Enjoy!



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