testing out subs

[BoneDance]

I have a set of subs that im trying to sell, but i wanna make sure they work, is there a place i can go to get them checked out and tested?

thanks

[ShermanEF9]

why not plug em in and see if they work?

[BoneDance]

dont have amps..or a car for that matter

[old man audio]

bring them down to the shop tomorrow and I will test them.

[Graham_A_M]

^ What kind of subs? I may be interested. I can try them out myself

[BoneDance]

http://forums.beyond.ca/st/279629/fs-resonant-engineering-12quot-mts-w-ported-box/

[slinkie]

absolutly phenomenal subs

yet you dunno if they work? :dunno:

[RossWRX]

You can touch the battery terminals on your car to the sub terminals quickly, it will cause the sub to move out and back.
This will insure that the voice coil is still intact and straight. If the sub moves fine and quietly, it's fine. (there should be no rattle or scratching when the cone moves)
Other than that look for any physical issues (torn spider or surround) and if everything checks out the subs are fine.

[Grogador]

Originally posted by RossWRX
You can touch the battery terminals on your car to the sub terminals quickly, it will cause the sub to move out and back.

:facepalm:

[n1zm0]

Originally posted by RossWRX
You can touch the battery terminals on your car to the sub terminals quickly, it will cause the sub to move out and back.

LOL please post a vid of your other electrical troubleshooting techniques

[chkolny541]

Originally posted by n1zm0


LOL please post a vid of your other electrical troubleshooting techniques

hes only kinda off to be fair,

http://www.crutchfield.com/S-OuEALdukE9T/tech/kb478.html

this says speakers, but i assume the same principle can be applied to subs. but i agree that perhaps the car battery could be alittle overkill

[Grogador]

Maybe with a 1.5v AA battery, but I wouldn't try it with a 12V car battery that would be pushing 1.5 to 6 amps through what's left of your coil.

[BoneDance]

Originally posted by slinkie


yet you dunno if they work? :dunno:


retail 529 is a ridiculous price
they better be phnomenal

[Graham_A_M]

Originally posted by RossWRX
You can touch the battery terminals on your car to the sub terminals quickly, it will cause the sub to move out and back.
This will insure that the voice coil is still intact and straight. If the sub moves fine and quietly, it's fine. (there should be no rattle or scratching when the cone moves)
Other than that look for any physical issues (torn spider or surround) and if everything checks out the subs are fine.

Please do everybody on here a big favor and dont offer any more advice. Seriously. :banghead:

The proper technique of doing this is to use a 9volt battery, as it does not carry enough power to fry the coil, or damage the woofers suspension.

an 800amp 12volt car battery? are you frickin NUTS?

[Toma]

Originally posted by Graham_A_M


Please do everybody on here a big favor and dont offer any more advice. Seriously. :banghead:

The proper technique of doing this is to use a 9volt battery, as it does not carry enough power to fry the coil, or damage the woofers suspension.

an 800amp 12volt car battery? are you frickin NUTS?

Huh... you know, I never thought about it before...

But, as I recall... ohms law is v=IR.... and since the voltage of a car battery is 12.7 volts, the sub has lets say a 4 ohm impedence... then the msot it could draw is roughly 3.5 amps, or a total power of about 44 watts...

I cant see this hurting the coil...

so this got me thinking.... if that is the case, and "amplifier" amplifies the voltage more than the current.... I mean if the amp tossed out 30 amps, it could kill you lol.

Am I thinking about this right?? lol

ok, ok, its late, jsut got me wondering lol.

[Toma]

Hello?? No on can explain this to me??

Just curious now lol

[Graham_A_M]

^ I'll explain this in detail.

Yes its true subwoofers MAY experience voltages & currents significantly more then 12.7 volts.
The differenciation is that those said voltages are in the form of various frequencies, not constant DC.

When the coil is allowed to move around (as in when you put typical music/frequencies into it) The constant rushing in and out of air (from the voice-coils own dust cap) aids in the cooling of the wire roundings of the coil. Through the vented pole piece, the air is bellowed in and out with each excursion stroke, thus keeping the voice coil cool. The more power you put into it, the more the cone moves and thus more bellowing of the air occurs. So it cools itself in quite a linear fashion, up until you get beyond the subs rated capacity. From there, the windings (& cooling design) may not be suffecient to handle the power you're inputing into the sub, and when that happens the glue that holds the copper wire onto the voice coil former begins to melt and "let go".

Thats why you may hear that scratching sound when subs are fried, or at least very close to being fried. Its from the copper wire winding scratching up againest the pole piece or magnet motor structure.

Anyway, that is part of the problem: but it also has something to do with how the voice coil reacts when placed in a fixed magnetic field. I forget that specific stuff since its been probably 9 years since reading up on it, and I seem to be the only person thats ever taken that sort of interest into these things, so I haven't talked about it in as long.

Simularily: when you push an amplifier beyond its limits, it creates great excesses of something called "Harmonic distortion".
Harmonics are what makes everything sound the way it does quite honestly.
A 150hz tone of a clarinet will sound very different then a 150hz tone from a guitar or a piano. Why? because of the very subtle (frequency) spikes at certain points within the tone/frequency itself. This gets really technical so I wont get into this too much:
but when an amplifier is pushed too hard: it generally sacrifices its ability to properly reproduce the sound (and all its harmonics), and thus creates square waves/"clipping". Remember how much the coil heats up when given full voltage and isn't allowed to move? thats basically what begins to happen to a much smaller of an extent. Subs can generally take some clipping, but too much and again the coils will cook. Thats why its a great idea to use a powerful amp, one that will never break a sweat powering your subs so you dont have to worry about this happening.

And yes, its very possible to be fatally electrocuted by the output of some very high wattage (SPL competition) amplifiers as they create voltages into the three digit range.

[misterrick]

future shop or visions does free testing if im not mistaken. sounds a lot friendlier than even trying a car battery....