Determining unknown speaker specs

[nicholas2381]

I'm finally digging through my project pile(s) and have come to my speaker graveyard.

I've got:

• 4 12" drivers (unknown)
• 2 5" drivers (Olson)
• 4 4" drivers (Koss)

All need re-foamed. That part is no big deal, I've already identified what surrounds I need for them based on physical measurements and plan to order them soon. I'm wondering if there's a way to determine the specs/characteristics (other than ohms) of each set in case I want to build a custom speaker project from this pile. Searching various numbers printed on the drivers has turned up bupkis. Any good tips?

 

[malden]

Any good tips?

post pictures, front and back

 

[Nat]

Determining the resonant frequency is pretty easy with a tone generator and a meter. Determining the various Qs is more complex, involving adding mass, and I've never done it.
I think Audio Xpress sells a device that can give you all or most of the TS parameters, but I have no experience of it.
If the drivers were pulled from cabinets, the speaker system specs can tell you much of what you might want to know.

 

[nicholas2381]

Photos

 

[nicholas2381]

Determining the resonant frequency is pretty easy with a tone generator and a meter. Determining the various Qs is more complex, involving adding mass, and I've never done it.
I think Audio Xpress sells a device that can give you all or most of the TS parameters, but I have no experience of it.
If the drivers were pulled from cabinets, the speaker system specs can tell you much of what you might want to know.

The Koss I believe come from the Koss M80, so I should be able to look those specs up.

The rest were dumped in my lap from a friend who had them dumped in his lap. So I dunno where they originated.

 

[nicholas2381]

I've got a signal generator and few meters. But I'm not sure investing a couple hundred bucks into the DATS tester is worth it for a tinkering project like this.

 

[GordonW]

Given the general construction, and the presence of "1098" in the number stamped on the magnet- I would posit that the woofers were probably made by Pyle.

Regards,
Gordon.

 

[GordonW]

As for alternative to buying something like a DATS unit- it is possible to do it with a good computer sound card. This is what the Google AI said (as far as I can tell, it's pretty much correct, BTW):

1. The DIY Sound Card / REW Method (Lowest Cost: ~$5 – $15)
If you already have a computer with a line-in/mic port or a basic USB audio interface and a cheap digital multimeter, you can build a simple impedance jig. [1]

• • Cost: $5–$15 (for a precision resistor, audio jacks, and wire) if you already own a multimeter and a scale. [1, 2]
  • What you need:
    • Free Room EQ Wizard (REW) software (has a built-in T/S parameter calculator tool).
    • A sound card with stereo line/mic input.
    • A small lead/reference resistor (e.g., 27 Ω to 100 Ω, 1% tolerance).
    • Alligator clips, a 3.5mm audio cable/plugs, and a digital multimeter.
    • A gram scale and a bit of Blu-Tack or clay for the added-mass method ($5–$10). [1, 2]
  • How it works: You wire a simple voltage-divider/impedance box between your headphone output and mic input. REW sweeps the speaker, measures the voltage drop across the reference resistor, generates the impedance curve, and calculates \(F_{s}\), \(Q_{ts}\), \(Q_{es}\), \(Q_{ms}\), and \(V_{as}\) via the added-mass routine.

I would refer to the REW documentation for more details on this process.

Regards,
Gordon.

 

[nicholas2381]

Thanks, Gordon - appreciate the info!