Why?? - Home Theater Forum and Systems - HomeTheaterShack.com

Old 02-21-14, 11:20 AM Thread Starter
Shackster

Shawn EZ McKenna

Join Date: Aug 2013
Location: Townsend,Wisconsin
Posts: 40
My System
Why??

This is a updated question about speaker ohms. If you read my question earlier you know I switched speakers in my sub from a 4ohm to a 8ohm speaker. My new question is, would the 8ohm speaker cause my amp in the sub to run hotter or use more power. The reason I ask is after switching speakers now my on board breaker keeps kicking out.
Is there a way to change the ohms of the amp\sub? I realize I can't change the ohms of the speaker of coarse. Just a shot in the the dark.
Thank you.

Shawn M.
eagletat is offline

Old 02-21-14, 11:42 AM
HTS Moderator

Joe

Join Date: Oct 2011
Posts: 7,209
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Re: Why??

Shawn,

I moved your post to the DIY forum as I thought you would get a quicker reply here. If I understand correctly, more ohms = more resistance so it would make sense that you would use more power and generate more heat to get the same listening level.

But, I will let the experts set me straight here...
ALMFamily is offline
Old 02-21-14, 12:17 PM Thread Starter
Shackster

Shawn EZ McKenna

Join Date: Aug 2013
Location: Townsend,Wisconsin
Posts: 40
My System
Re: Why??

Thank you

Shawn M.
eagletat is offline
Old 02-21-14, 12:31 PM
HTS Senior Moderator

Join Date: Sep 2008
Location: Newcastle Australia
Posts: 5,624
Re: Why??

Actually it is the opposite. The higher the speaker impedance the less power will be output for the same signal level.
The formula is P=Vē/R
So if you have a 4 Volt signal the 4 Ω speaker is 16/4 = 4 Watts whereas the 8 Ω is 16/8 = 2 Watts

Have you measured the resistance of the sub with a meter to verify it is 8 Ω

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Old 02-21-14, 12:39 PM
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Gary

Join Date: Dec 2008
Location: Dayton, Ohio
Posts: 123
Re: Why??

yea like stated if you replace a 4ohm driver with a 8 ohm driver.... the amp should be developing half or so of the power and also running cooler
Viggen is offline
Old 02-21-14, 01:01 PM
HTS Moderator

Joe

Join Date: Oct 2011
Posts: 7,209
My System
Re: Why??

Quote:
robbo266317 wrote: View Post
Actually it is the opposite. The higher the speaker impedance the less power will be output for the same signal level.
The formula is P=Vē/R
So if you have a 4 Volt signal the 4 Ω speaker is 16/4 = 4 Watts whereas the 8 Ω is 16/8 = 2 Watts

Have you measured the resistance of the sub with a meter to verify it is 8 Ω
Quote:
Viggen wrote: View Post
yea like stated if you replace a 4ohm driver with a 8 ohm driver.... the amp should be developing half or so of the power and also running cooler
Thanks for correcting me guys - learn something new every day!
ALMFamily is offline
Old 02-21-14, 01:14 PM Thread Starter
Shackster

Shawn EZ McKenna

Join Date: Aug 2013
Location: Townsend,Wisconsin
Posts: 40
My System
Re: Why??

I pulled it out of a working speaker box and it said 8ohm on the box and also the speaker. It was hooked up to my system until I upgraded to mtx aal 223s.
Is it possible that because the amp in my sub is 100w and the speaker is 250w max that could be causing a problem? It really shouldn't be I wouldn't think i was always told better under amped than over, right?

Shawn M.

Last edited by eagletat; 02-21-14 at 01:40 PM.
eagletat is offline
Old 02-25-14, 11:42 PM
Elite Shackster

Join Date: Jan 2014
Location: minnesota
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Definitely better to over amp than under.
willis7469 is offline

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