Speaker watt and ohm question.

Hollowbody · 11-06-2009, 06:51 PM

I'm sure the answer to this is on another part of this forum but I did a search with no luck.

If I have a speaker that has no markings and I have no idea of the manufacture or I'm not familiar with the speaker's history, how can I find the power and impedance rating?

I asked the local speaker guru and I guess he didn't understand the question, he seemed to be a little preoccupied. Must be all the glue in his shop, or doping the surround...

I guess I could just post pictures and someone would recognize it but I
would like to know how a person would know what to do to find out the tech info.

Is there a way to put a load on it then meter it?

thanks

Jesstaa · 11-06-2009, 06:56 PM

If you have a multimeter that reads ohms, just hook that up and check.

Hollowbody · 11-06-2009, 06:59 PM

Seriously? That simple? Cool.

What about power?

***Adwex*** · 11-06-2009, 07:15 PM

Quote:

Originally Posted by Hollowbody

Seriously? That simple? Cool.

What about power?

Yes, it's that simple. Just be aware that the DC resistance you measure with the meter will be slightly less than the actual AC impedance. For a "16 ohm" speaker, it might measure 15 ohms or so.

You can't really measure power handling capacity, thats a rating given by the manufacturer based on how much power the speaker can handle, so I wouldn't combine it with any less than 3 other speakers.

Jesstaa · 11-06-2009, 07:16 PM

Not sure about measuring the power, might be a little more complex.

Hollowbody · 11-06-2009, 07:41 PM

At least you put me on the right track though.

Thanks for the reply.

Wilder Amplification · 11-06-2009, 07:41 PM

Quote:

Originally Posted by Jesstaa

Not sure about measuring the power, might be a little more complex.

There's no way to. Power handling is based on heat tolerance of the components used, the travel limits of the mechanical assembly, magnet heat tolerance, etc etc.

Hollowbody · 11-06-2009, 11:00 PM

I really appreciate all the help.

So, for power, I guess my best option would be to hook it up and crank the amp it till it blows then take note of how well the speaker did then replace the motor and recone it.

Just kidding.

JohnH · 11-06-2009, 11:44 PM

If its a 12", maybe we could say that, unless it is visibly very old, and if it looks, smells, tastes (and sounds) like a guitar speaker, and if it is not entirely blue, its likely to be good for at least say 20W?

Just floating the thought

John

Hollowbody · 11-07-2009, 07:51 AM

Quote:

Originally Posted by JohnH

If its a 12", maybe we could say that, unless it is visibly very old, and if it looks, smells, tastes (and sounds) like a guitar speaker, and if it is not entirely blue, its likely to be good for at least say 20W?

Just floating the thought

John

Actually, you have good points.

There are three, each in some way unlike your description.

All 3 look ancient.

**One is an 8 inch ceramic, would seem useless but has a mean woody tone. Maybe good for recording an oddball track or two.

**Another is a 12 inch with a very small magnet and a second center concentric paper driver. Doesn't taste or smell like a guitar speaker but it has kind of a sweet sounding high end.

**And the last one has an old alnico mag and doesn't seem to produce anything above 4k.

I did meter the two 12's, they both come out to 8 ohm (7.5) so I am thinking they would make an interesting small 2x12 project for maybe a 5 or 10 watt amp.

Time to dig out the tung oil.

Hollowbody · 11-07-2009, 07:56 AM

...oh yeah, I guess helping a friend clean his garage can pay off in some small way.

Hollowbody · 11-14-2009, 12:44 PM

Here is another great one. Instead of making a new thread I thought I would tack it on to this one.

So, anyway, anytime I have done electronic projects and have used an LED for anything the needed info has been handed to me on a silver platter, IE: voltage rating, intended use etc, that also applies to the circuits I have built since the info is usually either online or with the package.

Sorry, no EE degree here, my soldering skills are well refined from working at a TV station for a decade and my ability to populate a PC board is no problem but I won't be designing any circuits anytime soon.

Same as the above mentioned speakers I have recently acquired a large bag of unmarked LEDs and have no way of finding out what they can handle. I have all ready blown a couple trying. I have a decent meter and even a cheaper student model Oscope (still learning how to use it) but I have no idea how to test these or any other diode for V-I or R.

As far as any circuit goes, (all things being equal) I would just check voltage at the junction, but the single component inherently doesn't give that much advantage.

I will also Google for this info but I mostly enjoy the response and info I glean from this forum.

Thanks

Wilder Amplification · 11-14-2009, 01:41 PM

Quote:

Originally Posted by Hollowbody

Here is another great one. Instead of making a new thread I thought I would tack it on to this one.

So, anyway, anytime I have done electronic projects and have used an LED for anything the needed info has been handed to me on a silver platter, IE: voltage rating, intended use etc, that also applies to the circuits I have built since the info is usually either online or with the package.

Sorry, no EE degree here, my soldering skills are well refined from working at a TV station for a decade and my ability to populate a PC board is no problem but I won't be designing any circuits anytime soon.

Same as the above mentioned speakers I have recently acquired a large bag of unmarked LEDs and have no way of finding out what they can handle. I have all ready blown a couple trying. I have a decent meter and even a cheaper student model Oscope (still learning how to use it) but I have no idea how to test these or any other diode for V-I or R.

As far as any circuit goes, (all things being equal) I would just check voltage at the junction, but the single component inherently doesn't give that much advantage.

I will also Google for this info but I mostly enjoy the response and info I glean from this forum.

Thanks

Usually with any LED running on low voltage, I install a 1K-2K resistor inline with the diode, and this usually allows them to work without frying.

Hollowbody · 11-14-2009, 03:29 PM

Quote:

Originally Posted by Wilder Amplification

Usually with any LED running on low voltage, I install a 1K-2K resistor inline with the diode, and this usually allows them to work without frying.

It's as if you truly feel my pain, many thanks.

11-06-2009, 06:51 PM	#1 (permalink)
Hollowbody Senior Member Join Date: Jan 2009 Location: Tulsa / Northern Texas. Posts: 271	Speaker watt and ohm question. I'm sure the answer to this is on another part of this forum but I did a search with no luck. If I have a speaker that has no markings and I have no idea of the manufacture or I'm not familiar with the speaker's history, how can I find the power and impedance rating? I asked the local speaker guru and I guess he didn't understand the question, he seemed to be a little preoccupied. Must be all the glue in his shop, or doping the surround... I guess I could just post pictures and someone would recognize it but I would like to know how a person would know what to do to find out the tech info. Is there a way to put a load on it then meter it? thanks

11-06-2009, 06:56 PM	#2 (permalink)
Jesstaa Senior Member Join Date: Apr 2009 Location: Gippsland, Vic, Australia. Posts: 797	Re: Speaker watt and ohm question. If you have a multimeter that reads ohms, just hook that up and check. __________________ GEAR LIST Marshall JCM900 4100 (6L6) (1995) Marshall Valvestate 1965A cab (????) Cort VX-2V (2008) TUBES/SPEAKERS Power: Groove Tube 6L6GCB Phase Inverter: Sovtek 7025 Pre: V1 - N.O.S Mullard ECC83. V2 National 12AX7A Speakers: Celestion G10L-35 Marshall forever My tube amp & Real Music appreciation forum

11-06-2009, 06:59 PM	#3 (permalink)
Hollowbody Senior Member Join Date: Jan 2009 Location: Tulsa / Northern Texas. Posts: 271	Re: Speaker watt and ohm question. Seriously? That simple? Cool. What about power?

11-06-2009, 07:16 PM	#5 (permalink)
Jesstaa Senior Member Join Date: Apr 2009 Location: Gippsland, Vic, Australia. Posts: 797	Re: Speaker watt and ohm question. Not sure about measuring the power, might be a little more complex. __________________ GEAR LIST Marshall JCM900 4100 (6L6) (1995) Marshall Valvestate 1965A cab (????) Cort VX-2V (2008) TUBES/SPEAKERS Power: Groove Tube 6L6GCB Phase Inverter: Sovtek 7025 Pre: V1 - N.O.S Mullard ECC83. V2 National 12AX7A Speakers: Celestion G10L-35 Marshall forever My tube amp & Real Music appreciation forum

11-06-2009, 07:41 PM	#6 (permalink)
Hollowbody Senior Member Join Date: Jan 2009 Location: Tulsa / Northern Texas. Posts: 271	Re: Speaker watt and ohm question. At least you put me on the right track though. Thanks for the reply.

11-06-2009, 11:00 PM	#8 (permalink)
Hollowbody Senior Member Join Date: Jan 2009 Location: Tulsa / Northern Texas. Posts: 271	Re: Speaker watt and ohm question. I really appreciate all the help. So, for power, I guess my best option would be to hook it up and crank the amp it till it blows then take note of how well the speaker did then replace the motor and recone it. Just kidding.

11-06-2009, 11:44 PM	#9 (permalink)
JohnH Senior Member Join Date: May 2008 Location: Wollongong NSW Posts: 640	Re: Speaker watt and ohm question. If its a 12", maybe we could say that, unless it is visibly very old, and if it looks, smells, tastes (and sounds) like a guitar speaker, and if it is not entirely blue, its likely to be good for at least say 20W? Just floating the thought John __________________ DSL401 8412 cab Crate Powerblock 1 x 12 Vintage 30 cab '76 Shergold Masquerader '93 Les Paul Studio '83 Roadstar

11-07-2009, 07:56 AM	#11 (permalink)
Hollowbody Senior Member Join Date: Jan 2009 Location: Tulsa / Northern Texas. Posts: 271	Re: Speaker watt and ohm question. ...oh yeah, I guess helping a friend clean his garage can pay off in some small way.

11-14-2009, 12:44 PM	#12 (permalink)
Hollowbody Senior Member Join Date: Jan 2009 Location: Tulsa / Northern Texas. Posts: 271	another stupid question. Here is another great one. Instead of making a new thread I thought I would tack it on to this one. So, anyway, anytime I have done electronic projects and have used an LED for anything the needed info has been handed to me on a silver platter, IE: voltage rating, intended use etc, that also applies to the circuits I have built since the info is usually either online or with the package. Sorry, no EE degree here, my soldering skills are well refined from working at a TV station for a decade and my ability to populate a PC board is no problem but I won't be designing any circuits anytime soon. Same as the above mentioned speakers I have recently acquired a large bag of unmarked LEDs and have no way of finding out what they can handle. I have all ready blown a couple trying. I have a decent meter and even a cheaper student model Oscope (still learning how to use it) but I have no idea how to test these or any other diode for V-I or R. As far as any circuit goes, (all things being equal) I would just check voltage at the junction, but the single component inherently doesn't give that much advantage. I will also Google for this info but I mostly enjoy the response and info I glean from this forum. Thanks

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