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Discussion Starter #1
My amp can do both, I think the 4ohm might sound better and cleaner; but I get more power at 2ohm.


Anyone else think this, or am I just imagining things?
 

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Your amp will deliver what your speakers require. If you have 4 ohm speakers, then the amp needs to put out more current, if you have 2 ohm speakers (never seen these in home speakers), then you one heck of a hardy amp!

You need to set the selector on the amp to match what your speakers are rated at.
 

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Discussion Starter #3
I'm looking to get new subs soon, and was wondering if there was any SQ difference between 2ohm and 4ohm speakers of the same brand and specs. (looking at soundplinters if anyone is curious) Obviously the 2ohm will be louder, but at what cost of SQ?


It sounds like you're saying speakers aside, the amp shouldn't have any SQ difference as long as it's rated for the load?
 

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You should understand as the impedance decreases...

The THD% will increase..

For example.. THD% into 4 Ohms will typically be 2x that @ 8 Ohms..


My suggestion would be to keep the amplifier loads to 4 Ohms or higher, as even if your amplifier is capable of driving 2 Ohms load it will draw significant current and get very warm..
 

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Quote:
You should understand as the impedance decreases...

The THD% will increase..

For example.. THD% into 4 Ohms will typically be 2x that @ 8 Ohms..
Why would you say that?
 

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Discussion Starter #6
I don't care if it gets warm, it is in a closet and has a big fan.


THD I do care about. I'll look into that! :)
 

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Discussion Starter #7
Hmmm, the specs say .1% THD at all impedience levels unless it's bridged, then it goes up to 1%.


Since it's a sub, that's still not bad, but I think I'll run 2ohms per channel. No reason to bridge.
 

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Discussion Starter #8
Quote:
Originally Posted by johnm_10
Hmmm, the specs say .1% THD at all impedance levels unless it's bridged, then it goes up to 1%.


Since it's a sub, that's still not bad, but I think I'll run 2ohms per channel. No reason to bridge.
Guess I should have read more carefully. It does infer that THD goes up as impedance goes down.


There is a disclaimer that the 2ohm .1% thd is only @ 1khz.


The .1% @ 20hz - 20khz has a lower power rating and is only available above 4ohms (8ohms bridged).


Conclusion: 4 ohms will sound better, especially at the lower frequencies.


Thanks M Code!
 

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Quote:
Originally Posted by johnm_10
Guess I should have read more carefully. It does infer that THD goes up as impedance goes down.


There is a disclaimer that the 2ohm .1% thd is only @ 1khz.


The .1% @ 20hz - 20khz has a lower power rating and is only available above 4ohms (8ohms bridged).


Conclusion: 4 ohms will sound better, especially at the lower frequencies.


Thanks M Code!


Noted... :)

Even though there will be an increase in THD%, if it is a quality designed/built amplifier this increase should not be that significant.. However it is crucial to note it is very easy to massage the THD % specs by increasing the feed-back..

However increasing the feed-back often destroys the stability of the amplifier under dynamic program driving conditions..


Again my input is to stay @ 4 Ohms..

There likely is more power output capability available @ 2 Ohms...

But then up goes the heat and current..


Just my $.02 worth.. ;)
 

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Quote:
Originally Posted by ChrisWiggles
Why would you say that?
Because the harmonics components will increase as the amplifier's load impedance decreases..
 

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Hmmm, the specs say .1% THD at all impedience levels unless it's bridged, then it goes up to 1%.
Why does bridging the amp increase the THD? The specifications in the owners manual of my amp states the THD is the same in both stereo and mono bridged modes.
 

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Discussion Starter #12
Quote:
Originally Posted by phisch
Why does bridging the amp increase the THD? The specifications in the owners manual of my amp states the THD is the same in both stereo and mono bridged modes.
I don't know what your book says, but mine says differently. I'm looking at the ep2500. It's a good value amp, but I'm sure there are better quality ones out there. By better quality I mean lower THD at higher levels and/or lower impedance, etc. Your amp may be better quality or something.


My guess is the thd goes up for bridging because you're using 2 channels to drive the same load, so the impedience on each channel is cut in half which raises thd.


This conclusion doesn't surprise me. Like I said going into this thread. I suspected the SQ was worse at 2ohms from my own ears, and was looking for verification.
 

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Quote:
Originally Posted by johnm_10
I don't know what your book says, but mine says differently. I'm looking at the ep2500. It's a good value amp, but I'm sure there are better quality ones out there. By better quality I mean lower THD at higher levels and/or lower impedance, etc. Your amp may be better quality or something.


My guess is the thd goes up for bridging because you're using 2 channels so the THD for each channel is added together to make a higher THD. Actually it seems to multiply itself by some factor in my case :)


This conclusion doesn't surprise me. Like I said going into this thread. I suspected the SQ was worse at 2ohms from my own ears, and was looking for verification.
Actually in certain instances when bridging an amplifier the THD may go down..

Bridging is essentially connecting 2 amplifiers in a push/pull configuration, power output can go up by a factor of 4..

But... But.. :)

There are no free rides.. :rolleyes:

Sometimes an amplifier may sound better when bridged...

and @ other times worst..

Also when an amplifier is bridged, one must careful for the wiring...

As now all connections are above ground, where as a conventional amplifier has 1 side grounded..
 

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Besides, even if the power is doubled, it's only 3dB increase, which should give a bit more headroom, but not really a significant increase in volume.
 

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Quote:
Also when an amplifier is bridged, one must careful for the wiring...

As now all connections are above ground, where as a conventional amplifier has 1 side grounded..
What does this mean in practical terms? I thought that when I flip the switch on the back of my amplifier from stereo to bridged that one of the positive terminals becomes ground. If this is not the case then what does that switch do?
 

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Discussion Starter #16
Quote:
Originally Posted by phisch
What does this mean in practical terms? I thought that when I flip the switch on the back of my amplifier from stereo to bridged that one of the positive terminals becomes ground. If this is not the case then what does that switch do?
Bridging is using an amp in a push/pull situation, instead of a push/neutral.


In other words, one channel is pushing power through the speaker, the other channel is pulling power through the speaker for a combined force of double what either channel can do alone.


When you're not bridged, each channel is pushing power through the speaker to the ground (neutral) which doesn't actively pull anything, it just absorbs.


There is alot more to it then that, but that should give you a picture of the basic idea in your head.
 
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