4 ohms/ 8 ohms speaker - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Chip Amps Amplifiers based on integrated circuits

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 10th September 2011, 11:46 PM   #1
epilot is offline epilot  United States
diyAudio Member
Join Date: Jul 2006
Default 4 ohms/ 8 ohms speaker

Hello guys,

Just want to see what is the difference between a 4 ohms speaker and a 8 ohms speaker other than the double current draw for the 4 ohms speaker than the 8 ohms one?

What about the loudness? Is the sound loudness is much higher when using a 4 ohms speaker instead of a 8 ohms? If not why use a 4 ohms speaker which draws a double current than a 8 ohms one?

Thanks a bunch
  Reply With Quote
Old 11th September 2011, 01:04 AM   #2
diyAudio Member
nigelwright7557's Avatar
Join Date: Apr 2008
Location: Carlisle, England
A 4 ohm speaker takes twice as much current for the same voltage so the amplifier must supply a lower voltage but twice the current.

For an 8 ohm speaker it needs more volts but half the current to get its rated output.
Murton-Pike Systems PCBCAD51 pcb design software. http://www.murtonpikesystems.co.uk
  Reply With Quote
Old 11th September 2011, 05:56 PM   #3
AndrewT is offline AndrewT  Scotland
diyAudio Member
Join Date: Jul 2004
Location: Scottish Borders
A 4ohm speaker should have the same efficiency as an 8ohm version of that speaker.
Both should have a sensitivity of XdB/W when measured by the same method.

There will be slight differences in the weights of the Voice Coils. This will have a slight effect on the relative efficiencies.

PA systems where dB is important to the audience, require dB more than almost other parameter bar intelligibility. Some installers forget this requirement.

To get big dBs it helps to use lower impedance speakers or to couple pairs of 8ohms speakers in parallel for more SPL.

I see no sensible reason to use 1, 2, 4, 6ohms drivers in any domestic listening speaker.
The 4ohms to 8ohms type should never be allowed, but that is a cost cutting exercise that the manufacturers jumped on. The combination of a 4ohm mid/bass and 8ohm treble driver allows the speaker to give a more balanced frequency response, without spending the appropriate costs to make a "good" speaker that will be suitable for 8ohm capable amplifiers.
regards Andrew T.
Sent from my desktop computer using a keyboard
  Reply With Quote
Old 12th September 2011, 01:05 AM   #4
epilot is offline epilot  United States
diyAudio Member
Join Date: Jul 2006
Thanks for all inputs,

I just want to see what is difference between a 4 ohms and a 8 ohms speaker while using them on the same amplifier without changing any other thing (i.e the power supply voltage and so on)?
I am eager to see what is the difference regarding the output SOUND?
  Reply With Quote
Old 13th September 2011, 06:47 PM   #5
diyAudio Member
Join Date: May 2008
Assuming you find two speakers that are absolutely equal except for the impedance you get
  • 3 dB more SPL for the same output voltage.
  • the same SPL for the same output power.
  • the same maximum SPL.
  • higher amplifier distortion for the same SPL.
  • double the heat dissipation for the same rail voltage.
If you've always done it like that, then it's probably wrong. (Henry Ford)
  Reply With Quote


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
8 ohms woofer plus 4 ohms tweeter? stf92 Multi-Way 9 27th August 2011 07:07 AM
15 ohms (12 on ohmmeter) with 24 ohms resistor in parallel to bring to 8 ohms McIntosh Man Multi-Way 29 11th June 2010 05:36 PM
ISOBARIC 16 ohms load powered by 8 ohms Amp eddi0 Subwoofers 24 21st October 2006 03:29 PM
Speakers: 8 ohms vs. 16 ohms KT Multi-Way 2 14th April 2006 05:06 PM

New To Site? Need Help?

All times are GMT. The time now is 05:56 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2