View Full Version : Using laptop instead of oscillator to test diaphragm inatallation

04-29-2009, 07:02 PM
After reading a post containing this information on proper diaphragm installation;

3. On drivers, hook unit up to oscillator set to 3-4 volts at proper frequency (550Hz on 1-inch drivers, 350 Hz on 2-inch drivers). Listen for buzzing. Use a small mallet to tap lightly on side of diaphragm frame until centered in gap and buzzing ceases. Tighten down diaphragm mounting screws.

I wondered whether I could perform a similar operation to test my new diaphragm install without an oscillator, but using my laptop instead.

I've downloaded an application called ToneGen that can play a 550Hz tone from my computer, but I'm wondering about the 3~4 volts output.

If I run a lead directly from the speaker or headphone jack (i.e. not using an amp), would this be around the mark, or am I way off base?

PLEASE NOTE: Heading should read installation, not inatallation. Sorry, I couldn't edit it!

04-29-2009, 07:50 PM
You would have to determine if your audio output device will really swing the voltage into that impeadance.

To find out you will need a good AC volt meter capable of accurate measurment at and above the frequencies you want to test at. Many inexpensive units are only accurate in the utility power range, 50-60 Hz, and a 10 Ohm 1watt or greater resistor.

240X drivers are about 10 Ohm through their usable range so...connect your output to a 10 Ohm resistor with your volt meter connected across the resistor and see where it stops as you increase the output volume of the device. You need a little over 3 volts to drive a watt of power through 10 Ohms.

The math is Volts squared divided by Ohms = Watts.

If it will do it, it will be loud! Have fun.

04-29-2009, 08:07 PM
Impedance! Crap, I totally forgot about that.
And here I was thinking it would be a piece of cake :banghead:

So would I be better off running the signal through my amp? I have one hooked up to the computer in my office. The impedance would be correct then, no? I could just play the 550Hz tone with my compression drivers hooked up and slowly wind up volume listening for any buzzing?

04-29-2009, 08:48 PM
Sure, just be carefull.

Unless you really trust your amp I would use a protection capacitor.

Earl K
04-30-2009, 04:15 AM
Hi lowpoke,

- You need clean amplication for any diaphragm alignment .

- Over driven oscillators ( or computer sources ) when connected directly to a driver result in a buzzing ( clipping ) distortion that you'll likely mistake for a problem with the driver.

>< cheers