Become a Supporting Member


Go Back   The Gear Page > The Gear > Amps/Cabs Tech Corner: Amplifier, Cab & Speakers Tech Discussions

Notices


Reply
 
Thread Tools Display Modes
  #16  
Old 09-17-2011, 06:46 AM
Scumback Speakers's Avatar
Scumback Speakers Scumback Speakers is offline
Crack Speaker Dealer
Feedback Score: 3 reviews
 
Join Date: Oct 2003
Location: Los Angeles, Ca
Posts: 8,349
Quote:
Originally Posted by frankie5fingers View Post
I'm curious. What, exactly, are the differences between a speaker of one ohm rating and another? I understand the reasons why we use different resistance(s), but I'm wondering how we create one vs the other. What actually "makes" the difference, wire, windings, what?
Thanks
The voice coil determines the ohm rating of a speaker. They are wound with different wire gauges to achieve the ohm reading. Typically a 16 ohm speaker uses a 13.4 ohm voice coil, and an 8 ohm speaker has a 7.2 ohm voice coil. This can vary slightly resulting in readings plus or minus 10-15%.

I've measured 16 ohm speakers with a multimeter and the range has been 14.2 - 12.9. For an 8 ohm speaker, the range is usually 7.4 - 6.9.

The cone, surround, doping, and dust cap do not set the ohm rating.

Hope that answers your questions.
__________________
Scumback Speakers
Scumback 4th of July Sale ends 7/31/14!

$20 off each speaker, free FBI w/4 ordered.
http://youtu.be/u6U30BV2kFM
Reply With Quote
  #17  
Old 09-17-2011, 07:41 AM
frankie5fingers frankie5fingers is offline
Senior Member
Feedback Score: 0 reviews
 
Join Date: Jan 2009
Location: OH... no
Posts: 1,443
It does...thanks. I was curious about the physical characteristics. I guessed the VC windings were key but wasn't sure if anything else was spec'd for a given resistance.
Thanks again, Frank
__________________
"Quotation: The act of repeating the words of another erroneously" - A. Bierce
Smooth transactions with 100 or so TGPers, several dozen Ebayers (100% feedback) and hundreds of deals made the old fashioned way ... in person.
Reply With Quote
  #18  
Old 09-17-2011, 08:27 AM
Scumback Speakers's Avatar
Scumback Speakers Scumback Speakers is offline
Crack Speaker Dealer
Feedback Score: 3 reviews
 
Join Date: Oct 2003
Location: Los Angeles, Ca
Posts: 8,349
Quote:
Originally Posted by frankie5fingers View Post
It does...thanks. I was curious about the physical characteristics. I guessed the VC windings were key but wasn't sure if anything else was spec'd for a given resistance.
Thanks again, Frank
You're welcome, sir. While the voice coils can have different former materials (paper, kraft paper, nomex paper, kapton, etc) that will allow higher temperatures to be sent to them (i.e. more power produces more heat) without melting/failure, that doesn't change the ohm rating. They can have an effect on tone with the different former materials.

But basically when using a given wire gauge, and winding it X number of times, you get a particular ohm rating.
__________________
Scumback Speakers
Scumback 4th of July Sale ends 7/31/14!

$20 off each speaker, free FBI w/4 ordered.
http://youtu.be/u6U30BV2kFM
Reply With Quote
  #19  
Old 02-21-2012, 11:36 PM
jamison162 jamison162 is offline
Supporting Member
Feedback Score: 1 reviews
 
Join Date: May 2006
Location: FL
Posts: 7,796
Quote:
Originally Posted by CharlyG View Post
It mostly has to do with cabs with multiple speakers. If the speakers in a 4x12 were 4 ohm the cab would show a 1 ohm load! 16 ohm spkrs would show 4 ohms and 32 ohm spkrs, 8.
Which is typically NOT how speakers are wired in a 4x12. Don't confuse people. Most of the time they are wired in parallel/series pairs. 4 x 16 ohm speakers = 16 ohm cab; and the only way to wire an 8 ohm 4x12 cab is to use 4 x 8 ohm speakers...noone makes 32 ohm speakers that I know of.
Reply With Quote
  #20  
Old 02-22-2012, 12:13 AM
Sweetfinger Sweetfinger is offline
Senior Member
Feedback Score: 0 reviews
 
Join Date: Jul 2008
Location: Phoenix, AZ
Posts: 5,971
Quote:
Originally Posted by jamison162 View Post
...noone makes 32 ohm speakers that I know of.
Actually not as uncommon as you might think.
http://www.fliptops.net/catalog/prod...roducts_id=325
The Jensen P-12Q is also available in 32 Ohms. Doing a Google search for "Eminence 32 ohm" kicks up a big list of Eminence speakers in 32 ohm, so they are out there. IIRC the speakers in a Fender Bassman Ten combo are 32 ohms.
__________________
I do my work at Precision Guitar, a semi-secret above ground research laboratory and adult day-care center. We also fix guitars.
Reply With Quote
  #21  
Old 02-22-2012, 04:43 AM
SatelliteAmps SatelliteAmps is offline
Senior Member
Feedback Score: 0 reviews
 
Join Date: Oct 2007
Location: Normal Heights, Calif
Posts: 6,146
Quote:
Originally Posted by jamison162 View Post
Which is typically NOT how speakers are wired in a 4x12. Don't confuse people. Most of the time they are wired in parallel/series pairs. 4 x 16 ohm speakers = 16 ohm cab; and the only way to wire an 8 ohm 4x12 cab is to use 4 x 8 ohm speakers...noone makes 32 ohm speakers that I know of.
Confuse people? You have posted four comments tonight about impedances, and all of them have been grossly wrong and misleading.

Some 4x12s are wired in either series/parallel or parallel/series. Some are wired in series only, and some in parallel. Each version has its pluses and minuses.

There are three ways to wire a 4x12 to get 8Ω. A quad of 8Ω wired in either series/parallel or parallel/series. A quad of 32Ω wired in parallel, or a quad of 2Ω wired in series. There are 2Ω speakers in this world. Never seen them in a guitar cab, but they do exist.
__________________
Adam Grimm
Satellite Amplifiers®
www.satelliteamps.com
www.myspace.com/satelliteamps
619-275-2255
Reply With Quote
  #22  
Old 02-22-2012, 09:04 AM
Ronsonic Ronsonic is offline
Senior Member
Feedback Score: 0 reviews
 
Join Date: May 2006
Location: Sunny Tampa, Florida
Posts: 3,165
Just a couple of comments.

There's a missing word in our conversation, "NOMINAL."

The actual impedance of a speaker is all over the place, depending on its own resonances and the cabinet it is in. So the number printed on the back is its nominal impedance.

32R speakers are relatively rare but not unheard of. Fender used them in the Bassman Ten and the Rhodes amps. See them in a lot of old PA gear.
__________________
Disclosure: I build, fix and sell Electro-musical gadgets for profit.
My blog is stale and never gets updated.
Reply With Quote
  #23  
Old 02-22-2012, 09:32 AM
jamison162 jamison162 is offline
Supporting Member
Feedback Score: 1 reviews
 
Join Date: May 2006
Location: FL
Posts: 7,796
Quote:
Originally Posted by SatelliteAmps View Post
Confuse people? You have posted four comments tonight about impedances, and all of them have been grossly wrong and misleading.
Well my point is 2ohm and 32ohm guitar speakers, while they may exist, are certainly not the norm. As far as my other posts, nothing was stated as fact...I always base my posts on personal opinion and experience so take it at face value.

The post I had commented on (#13, re: 32ohm speakers) really has no relevance in guitar speaker application (for the most part). I.E. didn't want to see someone on a wild goose chase trying to locate 32 ohm speakers so they could wire up an 8 ohm cab, hahahaha!
Reply With Quote
  #24  
Old 02-22-2012, 02:56 PM
donnyjaguar donnyjaguar is offline
Senior Member
Feedback Score: 0 reviews
 
Join Date: Nov 2005
Location: Canada
Posts: 3,706
Quote:
Originally Posted by Ronsonic View Post
Just a couple of comments.

There's a missing word in our conversation, "NOMINAL."

The actual impedance of a speaker is all over the place, depending on its own resonances and the cabinet it is in. So the number printed on the back is its nominal impedance.
.
This is a very good point. The term nominal mean "in name only". Some speakers can be many times their nominal impedance at certain resonant frequencies. If you use them in series it will exaggerate this difference, which may not be good.
__________________
If nobody laughs at your dreams they aren't big enough :)
Reply With Quote
  #25  
Old 02-22-2012, 04:57 PM
SatelliteAmps SatelliteAmps is offline
Senior Member
Feedback Score: 0 reviews
 
Join Date: Oct 2007
Location: Normal Heights, Calif
Posts: 6,146
Hands up, how many people here actually have something that truly measures impedance?
__________________
Adam Grimm
Satellite Amplifiers®
www.satelliteamps.com
www.myspace.com/satelliteamps
619-275-2255
Reply With Quote
  #26  
Old 02-23-2012, 10:21 AM
Ronsonic Ronsonic is offline
Senior Member
Feedback Score: 0 reviews
 
Join Date: May 2006
Location: Sunny Tampa, Florida
Posts: 3,165
Quote:
Originally Posted by SatelliteAmps View Post
Hands up, how many people here actually have something that truly measures impedance?
Me.

And I rarely bother. It's work.

Usually, I, just like everybody else just use DCR as a stand in - I also use my Dick Smith (stop snickering) ESR meter for a quick look at whether a thing is inductive. On most 50ish watt amps it will show something like the nominal impedance of output transformer taps. It's an accident of design, but handy enough. More quicker and better than Ohming them out with a DC meter and sorting the .45R, .6R and .8R leads.
__________________
Disclosure: I build, fix and sell Electro-musical gadgets for profit.
My blog is stale and never gets updated.
Reply With Quote
  #27  
Old 02-24-2012, 08:45 AM
donnyjaguar donnyjaguar is offline
Senior Member
Feedback Score: 0 reviews
 
Join Date: Nov 2005
Location: Canada
Posts: 3,706
Quote:
Originally Posted by SatelliteAmps View Post
Hands up, how many people here actually have something that truly measures impedance?
You don't need this fancy gear to measure impedance. A tone generator, multimeter & resistor is all that's needed. Basic workbench tools brutha.
__________________
If nobody laughs at your dreams they aren't big enough :)
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 05:51 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Copyright ©1999-2014, The Gear Page, LLC, Brian Scherzer
All rights reserved.
Banner Design: Chris Sileo