Self-contained LIMP jig.

[audioanarchist]

Re: Self-contained LIMP jig.

So would this not work as well for gathering t/s parameters of a subwoofer with a low fs?

[Pete Basel]

Re: Self-contained LIMP jig.

So would this not work as well for gathering t/s parameters of a subwoofer with a low fs?

No it would not, it will barely get it moving.

I think it is ridiculous not to use a power amp.

[johnnyrichards]

Re: Self-contained LIMP jig.

Either of you care to define the Fs limits of this device?

[audioanarchist]

Re: Self-contained LIMP jig.

Either of you care to define the Fs limits of this device?

I have no clue that's why I was asking. This thing is awesome, I just wanted to make sure I know what it can and can't do.

[JasonP]

Re: Self-contained LIMP jig.

The driver I have sitting loose now with the lowest Fs is a Dayton DA270 10" Aluminum. Fs is a mere 30 hz, and using my jig after a little break-in I got T/S matching the published spec nearly on the money.

The accuracy should drop the lower the Fs goes, but I think you'll be fine with drivers that have Fs 20 hz or above, in my experience.

[audioanarchist]

Re: Self-contained LIMP jig.

Thank you Jason. That's exactly what I needed to know. Seems like it's nothing to really worry about. I can't wait to get mine slapped together.

[kevintomb]

Re: Self-contained LIMP jig.

As far as details, Kenny - just this schematic:

[ATTACH=CONFIG]52566[/ATTACH]

Can't take credit for it however, it is pretty standard. I drew this schematic since some of the examples I found on the interwebz did not make a lit of sense to me, and I actually used a pair of 200 ohm resistors in parallel.

What schematic would be used, when using an external Amp?

I plan on using about a 16 ohm resistor.

I see the mention in the manual about using zener diodes, and 2 resistors, but their schematic is confusing. ((Drawing 3.2 and 3.3)) Not sure how they are combining them.

[JasonP]

Re: Self-contained LIMP jig.

What schematic would be used, when using an external Amp?

I plan on using about a 16 ohm resistor.

I see the mention in the manual about using zener diodes, and 2 resistors, but their schematic is confusing. ((Drawing 3.2 and 3.3)) Not sure how they are combining them.

Those circuits are for high power testing. Your sound card can't handle the voltage output of the amplifier directly, so it scales down the voltage to a level it can handle. The R1 and R2 function as a voltage divider to do just that. The two zener diodes placed across the sound card input will trip if the voltage is too high, create a short in the circuit, and protect it from possible overload.

If you are doing low voltage testing and have a way to ensure no accidental high voltages reach the sound card (using a DMM to test the output, etc) then you can just use the 16 or 27 ohm resistor setup with the amp output as presented.

[kevintomb]

Re: Self-contained LIMP jig.

Those circuits are for high power testing. Your sound card can't handle the voltage output of the amplifier directly, so it scales down the voltage to a level it can handle. The R1 and R2 function as a voltage divider to do just that. The two zener diodes placed across the sound card input will trip if the voltage is too high, create a short in the circuit, and protect it from possible overload.

If you are doing low voltage testing and have a way to ensure no accidental high voltages reach the sound card (using a DMM to test the output, etc) then you can just use the 16 or 27 ohm resistor setup with the amp output as presented.

Okay so they are showing the sound card LEFT and RIGHT inputs on the right side of the drawing, with the amp outputs from either side of the 27 ohm resistor as being on the left side of the drawing.

[JasonP]

Re: Self-contained LIMP jig.

Without the protection circuits, you just follow the diagram JR posted above but use the smaller resister instead of the 100 ohm.

[JRT]

this deserves a fresh bump to the top of the stack of threads