Audio (and aftermarket electronics) This is your place for alarms, remote starters, to brag about your system, exaggerate your db levels, or simply ask questions for stock or aftermarket audio. No Flames! (except from roasted amps)

How to measure ohms with a DMM?

Thread Tools
 
Search this Thread
 
Old 10-04-2010, 07:32 PM
  #1  
Senior Member
True Car Nut
Thread Starter
 
raptor660's Avatar
 
Join Date: Mar 2010
Location: Eaton Rapids MI
Posts: 2,964
Likes: 0
Received 0 Likes on 0 Posts
raptor660 is on a distinguished road
Default How to measure ohms with a DMM?

I just got a 15" FI Q sub and am not sure if the its dual 2 ohm or dual 1 ohm voicecoil.
Since is a custom made sub there isnt a stamp on the magnent stating which voice coils it has.
The guy said its a dual 2 ohm sub but then he said it was wired to 2 ohms. Well u cant wire a dual 2 ohm sub to 2 ohms. and yes both voicecoils are being used. lol

so how did i find out with a digital multi meter?
Old 10-04-2010, 08:18 PM
  #2  
Senior Member
True Car Nut
Thread Starter
 
raptor660's Avatar
 
Join Date: Mar 2010
Location: Eaton Rapids MI
Posts: 2,964
Likes: 0
Received 0 Likes on 0 Posts
raptor660 is on a distinguished road
Default

I figured it out... Each voice coil measured 2.4 ohms.
Good thats what i needed! Wiring it to 4 ohms and bridging one of my amps to it. just not sure which one
Old 10-04-2010, 10:18 PM
  #3  
Senior Member
Posts like a Turbo
 
04MonteLS's Avatar
 
Join Date: Jul 2010
Location: Sacramento, CA.
Posts: 326
Likes: 0
Received 0 Likes on 0 Posts
04MonteLS is on a distinguished road
Default

Those subs are monsters, they're gonna laugh at that power though.
Old 10-04-2010, 10:18 PM
  #4  
Senior Member

True Car Nut
 
sseidriver97's Avatar
 
Join Date: Mar 2010
Location: Portage mi
Posts: 7,124
Received 5 Likes on 5 Posts
sseidriver97 is on a distinguished road
Default

so now you can sell me or trade lol your two 15'*
Old 10-04-2010, 11:09 PM
  #5  
Administratus Emeritus
Certified Car Nut
 
GXP Venom's Avatar
 
Join Date: Jan 2006
Location: Purgatory, Pennsylvania
Posts: 16,539
Received 15 Likes on 10 Posts
GXP Venom is on a distinguished road
Default

If they were wired in parallel, they would still pull 2 ohms.
Old 10-04-2010, 11:26 PM
  #6  
Senior Member
Posts like a Turbo
 
04MonteLS's Avatar
 
Join Date: Jul 2010
Location: Sacramento, CA.
Posts: 326
Likes: 0
Received 0 Likes on 0 Posts
04MonteLS is on a distinguished road
Default

Originally Posted by GXP Venom
If they were wired in parallel, they would still pull 2 ohms.
Who are you talking to and what are you talking about?
Old 10-05-2010, 03:57 AM
  #7  
Senior Member
True Car Nut
Thread Starter
 
raptor660's Avatar
 
Join Date: Mar 2010
Location: Eaton Rapids MI
Posts: 2,964
Likes: 0
Received 0 Likes on 0 Posts
raptor660 is on a distinguished road
Default

I traded my 15" JL W0'* for this sub sorry Dude... my buddie said each coil is supposed to measure 1.5 for the dual 2 ohm FI Q.. is that true? did i just measure it wrong?
Old 10-05-2010, 09:29 AM
  #8  
Administratus Emeritus
Certified Car Nut
 
GXP Venom's Avatar
 
Join Date: Jan 2006
Location: Purgatory, Pennsylvania
Posts: 16,539
Received 15 Likes on 10 Posts
GXP Venom is on a distinguished road
Default

Originally Posted by 04MonteLS
Who are you talking to and what are you talking about?
I'm talking to the OP about his question "The guy said its a dual 2 ohm sub but then he said it was wired to 2 ohms"


He'* correct about the 1.5 ohms Raptor. But thats an approximation. To really measure true impedance of a speaker or cabinet requires a rather complex procedure involving a signal generator, power amplifier, and a high frequency AC voltmeter. However, with raw speakers and many cabinets, the ohmmeter function of a digital multimeter can help you identify what the impedance of the speaker should be. Generally, the reading given by an ohmmeter will be about 2/3 to 3/4 of the impedance of the speaker. So, a 4 ohm speaker will typically measure about 2.5 - 3 ohms,a 8 ohm speaker will typically read about 5-6 ohms, while a 16 ohm speaker will measure around 12 ohms. So according to your measurements of 2.4 ohm'*, those are 4 ohm speakers. BTW, Cheap multimeters vary greatly for small voltage or ohmage readings.
Old 10-05-2010, 06:27 PM
  #9  
Senior Member
True Car Nut
Thread Starter
 
raptor660's Avatar
 
Join Date: Mar 2010
Location: Eaton Rapids MI
Posts: 2,964
Likes: 0
Received 0 Likes on 0 Posts
raptor660 is on a distinguished road
Default

Thanks LSMONTE.
And Venom u never seize to amaze me with ur broad range of knowledge.
I tried to hook my new system up but when i turned it up all three of my fuses in my amp popped..
I guess my amp just cant push this FI Q
Old 10-05-2010, 07:56 PM
  #10  
Administratus Emeritus
Certified Car Nut
 
GXP Venom's Avatar
 
Join Date: Jan 2006
Location: Purgatory, Pennsylvania
Posts: 16,539
Received 15 Likes on 10 Posts
GXP Venom is on a distinguished road
Default

Meh, I learned alot of electrical engineering being a contractor of various sorts, been blowing chit up in my cars for almost 40 years, and I hang out at the Custom Shop that did my car alot. I definitely not an audio tech.


Quick Reply: How to measure ohms with a DMM?



All times are GMT -4. The time now is 05:55 PM.