Thursday, May 22, 2008

Doesn't Blow

Inflatable Keyboard Speaker/Mic

A handy item that floats, this air-filled keyboard can be rolled up when not in use, or combined with an airbag in an Escalade to allow fast texting while in transit on a congested freeway. By making the keyboard out of a piezopolymer such as polyvinylidenediflouride, one can make it work like a mic or a speaker, or both at the same time. A highly vibratory and button intensive appliance, this scheme was talked about for many years as the answer to portable computing, disposable computing, seaworthy typewriting, infant care touch type training, and even hospital sterile field data entry.

Sponge Mic Sound Absorbing Wet Transducer

.....or we could call it a water-coupled transducer. The use of a porous material for a transducer is actually not a new idea. This novelty sponge is made to be used in the bath and appears to be a die-cut piece of ordinary sponge like you have in the kitchen. Sponges can be made of a piezoelectric polymer and can emit sound when excited by AC, or they can act as a transducer, either a pressure transducer, or sonic. The foraminous nature of a sponge makes it easier to acoustically match it to its surrounding sound conducting medium. Water is an excellent and low loss conductor of sounds of all frequencies, air less so, and confined mostly to frequencies below 500 kHz or so. I don't know where I can buy these but you could make your own with a sponge and a scissors. I imagine that a 77DX-shaped sponge would be easy to make, and of course one in the shape of a U-47 might be of interest. How about one shaped like a Shure 55C? That would be pretty cool.

Wednesday, May 21, 2008

Ozzy "Mr Crowley" Pin

Someone gave me this pin in the late 70s and it was stashed away in a stash box until I recently came across it.

Here it is on the headstock of that old Hofner Verithin that we use in our banners on Gearslutz and Harmony-Central, and other places. As you can see, the shellac over the mother-of-pearl inlay is a bit flaky, and the observant of you will note that these are Shallers and not the stock tuners. I have them, or should I say, five of them that I could put back to make the guitar "stock" once again. The sixth was broken when I got the guitar. Anybody have a spare yellow tuner for a Hofner? 60s vintage?

Modded "Black" head-type

After playing around with this mic I decided we had better just finish it up, and let that be it.

This one did get a Roswellite Ribbon that exceeds the performance of the original. The transformer size and the acoustics are still a limiting factor.

We powder coated this mic a nice, satin black, and it looks ok. Also added an angle dial to the base, and plugged it right into the test block for some measurements.

Thursday, May 08, 2008

Lauren Passarelli - Please Feel Free

Lauren is a great friend and one of our favorite artists. We listen to her CD with this song on it over and over.

Here is Lauren zooming around on a Segway demonstrating a masterful riding style that fits well with her music on this video.

Click on the image to see Lauren go! Be sure to turn up the volume, and put on your headphones too..

Friday, May 02, 2008

Mod Project on a Low Cost Ribbon Mic

The mic shown on the right is just one of the myriad of differently labeled inexpensive ribbon mics.. They are single ribbon jobs with a plain steel flux frame mounted in a circular body. All of the ones I have seen including this one have only two of the four screws in place - it seems only two line up and the other two do not. Two are enough to keep the frame in the circle. Since this is generic, and not any "brand", it's fair to make this a mod subject for the blog.

Mike at Cascade has fixed the screw line up problem in his mics and has put some effort into other improvements.

Click on the image for a real close-up.

The contact at the bottom is a piece of G10 with a tinned copper trace where the ribbon goes. The flux in the gap measures 3500 Gauss, and the dimensions of the gap and its length, and the overall size of the flux frame, are all the nearest metric equivalents to another common ribbon microphone, but without the stepped sides and grooves.

This mic is generally the same as you see all over the place with various names and paint jobs. It has a hanging EI transformer which is encased in a plated brass tube.

It would be interesting take this apart and give it a good powder coat finish, maybe do something with the magnets and transformer or magnetic shielding, put in new ribbon, and find out what kind of performance we can get. Like the "tube ribbon" we looked at a while back, we got this as a sample.