THE CHALLENGE was to install a pickup and amplify the sound of "El Doble", the two string bass that I created this summer. I accompanied Pat MacDonald and his Ubass at a retirement home mini-concert Sunday and it was obvious I needed a little amplification in the midst of his Ubass and fifteen ukulele players strumming and singing. Pat said, "that thing has good tone, you ought to put a pickup in it" and the fire was lit. I have been trying to figure out how to do it ever since. today I thought I had it figured so after lunch I entered the workshop full of hope and a plan. Here is what happened.
The plan and the hope was that I could use one of the neat MiSi uke pickups and jacks to electrify El Doble. These marvelous devices have worked so well in the many ukes I have installed them in, but how to connect to a cello like instrument with no bridge, no saddle notch and not saddle to compress it under.
The idea was to cut a notch under the two feet of the bridge for the piezo just shallow enough to fit the piezo into and still press it onto the surface of the instrument top. If it were too loose the piezo would not pick up the vibrations. Too tight and the bridge feet would be raised above the top and perhaps there would be too much pressure on the piezo. This looked about right. | Here is how I cut the slot in the experimental bridge. I used the sled, held a square and the bridge together and ran it over the barely protruding saw blade. And this was the pleasing result, a perfectly wide groove just deep enough to accept most of the piezo |
This looks just right, now I know where the bridge goes on the instrument top, but where do I dare drill the hole to bring the piezo through the top. There are braces down there and I don't want to hit one. Ah!, an idea strikes Now it was time to install the jack in the side of the instrument. I use a step drill because I have found it cuts perfectly, with no risk of ripping up the wood, and it's widest step is just the proper diameter for the MiSi. On the right is the perfect hole that it cuts ready to install the jack that will accept both the charger of its capacitor, and also the amplifier cord. I was very appreciative of the large sound hole which allowed me to push the MiSi jack through this little hole from inside. Far easier than installing in a ukulele. | I had recently bought some cool magnets with handles from Stew-Mac. here was their first use. I put one magnet underneath the top by reaching through the sound hole. The other magnet shown in the picture above, quickly aligned with its mate and I was able to move them both to a place just over the location of the bridge. Knowing now that there was no brace underneath I marked the hole -to be drilled, location just under the magnet. |
And here it is tightly installed into the side of the bass. A finial which doubles as a strap button threads onto this, improving its appearance considerably. I will not be needing a strap on this monster, but I like the finished look. Into this hole goes all the electric cables both for powering the capacitor and for connecting to the Amp. | It was an easy matter to put my hand into the sound hole, grasp the piezo and feed it up through the little hole I had located with the magnets and drilled through the soundboard. |
I laid the piezo under both feet of the bridge so that about three inches of it was exposed to the soundboard. tightened the strings again and approached the moment of truth. Now I plugged it into the Amp, turned the amp on, plucked a string and almost got blown out of the workshop. Wow ! this thing works too well. The amp turned to its lowest point still was way too loud, getting far too much input from the pickup. What to do? | But first I had to power up the pickup capacitor. I plugged it in for 60 seconds which fully powered it for up to 16 hours of playing. Now for the moment of truth. After a little thought I simply pulled the piezo back into the hole leaving it only under one foot of the bridge. I had reduced it's contact with the bridge and the top by more than 50%, and now it was PERFECT. I am just delighted. The sound is great, the pickup is not visible, playing is so much easier since I don't need to pluck strings hard but can choose the level of attack. Amplification has made this a truly worthwhile instrument and I can hardly wait to get it to the November BUG jam where I plan on playing it the entire time. A great afternoon in the workshop. |