Official Luthiers Forum!

Hello to all,

With the growing interest in free plate tuning and the here for necessary signal generator/amplifier setup,
I thought I gave you an impression of mine and how I got there. There are several ways to go about this.

One way is to use some audio software on a computer with a decent soundcard and wire the output to
an amplifier connected to a speaker.

Some decent (Windows) software can be found at http://www.audiotester.de/ (also English version).
But there are many more.

An other approach would be to buy a stand-alone signal generator and an amplifier.
I had some restrictions or shall I say “User requirements” for the setup.

I don’t want to use my (expensive) laptop computer in my shop with al the dust etc. around. I have a (very) small shop
so space is also an issue. The setup has to stay for a while (or be around for ever, who knows) and
I don’t want to dedicated a workbench for it.

I looked at some new signal-generators. They start at about EUR 250,--.
They have a lot of functionality (different signal waves, more channels etc.), which I actually didn’t needed.
They don’t have an amplifier on board so an external amplifier is necessary.
You can buy a used signal-generator. But mostly the ones offered have no kind of electronic display so a (extra)
frequency counter (or oscilloscope) is required to see what kind of frequency you’re actually using.

So not really happy with the possible solutions, I questioned/google-ed some more and I found out that there
was actually a device build, especially for plate tuning.

This (small) signal-generator is build by Don Bradley – Bradley Engineering (Forestville – CA 95436 USA).
e-mail: sonomadb@sonic.net, Tel: (707) 887-9746

I contacted him through e-mail and learned that he has two versions: the Siggen 5L and 5H.
The only difference between them is the Audio amplifier. The L-version has 25 Watt, the H-version 45.

It turns out that the 25 Watt is usually used for Steel string/Violins/Mandolins, the 45 Watt for Cello/Arch-top.
The price is $ 500,-- for each version. I bought the Siggen 5L and got it promptly by UPS.

The device is small/portable and well engineered. You notice when using the generator that it is made for the plate tuner in mind.
There a two knops for adjusting the frequency. You can store up to 16 default frequencies easily and recall them when you need them.
The mute switch is also very handy: you don’t have to turn the generator of if you want to make some adjustments/shave bracings. Just mute it.
The generator comes with a Phone Jack cable so you can connect your speaker (solder) directly.

Icing on the cake would be a speaker, glitter and some ear protection delivered with it. Maybe with a XL version…


Hopes this helps. I got some ring closing to do!


Kind regards,


Edzard

I have heard nothing but good things about Don's signal generator. I'm pretty sure that Al helped Don with the specs. I don't own one but Al's is pretty nice.

I cheaped out and bought a different signal generator. It is the Madell 1635. It doesn't have the precision that Don's generator has and only measures the frequency to 1Hz. The frequency seems to shift when the output voltage is all the way up. It doesn't have an audio amplifier so I run it through an old guitar amplifier that I had lying around (who doesn't?). It does the job but Don's generator is better and I often wish that I had bought that one. In fact, I may anyway.

I was at my brother-in-laws the other day and he was showing me some iPhone apps that he has written. One was a signal generator. It has sine, square, triangle, and sawtooth wave forms and goes from 1Hz to 20,000Hz. If you have an iPhone you carry your signal generator with you and all you need in the shop is an amplifier.

Is your brother-in-laws app available for all.

I have an Itouch. An Itouch with the right app, and a powered computer monitor speaker would be a slick way to go.