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cabinet speakers/amp

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dphirschler:

--- Quote from: timoe on May 10, 2005, 08:31:40 pm ---Watch out what you connect those partsexpress speakers to dphirschler, they're impedence is rated at 8 ohms and they handle 5 watts each.
--- End quote ---

Timoe:
I don't know that much but I DO know that impedence (ohms) is important.  Most speakers nowadays (i think) use 4 ohms, like car speakers or comp0uter speakers.  Guitar amp speakers sometimes are 8 or 16 ohms.  But if the speaker can only handle 5 watts it wont get too loud.  And if your comp speaker amp pumps out more than 10 watts it may mess up your speakers at the higher volumes.

dphirschler:
OK, I just read some info on partsexpress.

tivogre:

--- Quote from: dphirschler on May 11, 2005, 12:16:48 pm ---OK, I just read some info on partsexpress.  Here is what they say aboug ohms.


--- Quote ---It should be observed that providing a lower impedance than the amplifier's documentation specifies can lead to damaging levels of current passing through the amplifier. For example, if an amplifier is rated for 8Ω and the speakers are connected to provide 4Ω, twice the current will be passing through the amplifier than it would with 8Ω and be a potential hazard. Accordingly, if an amplifier is rated for 4Ω and is presented an 8Ω load, half of the current will pass through the amp and the overall sound pressure level will be decreased, compared to the rated 4Ω load. This will be safe for the amplifier, but it will not be an optimal usage of the amplifier's power.
--- End quote ---

Looks like I will be safe connecting 8 ohm speakers to a 4 ohm amp, although not optimal.  I understand that if I connect two 4 ohm speakers in parallel (per channel) it will reduce the load to 4 ohms.  I wonder if connecting a 4 ohm resister in parallel will accomplish the same thing.


Darryl

--- End quote ---

I thiunk you meant 2 8 ohm speakers in parallel will give you a 4 ohm load.

2 4 ohm speakers in parallel will give you a 2 ohm load... and almost certainly fry your amp.

2 4 ohm speakers in SERIES, however, will give you an 8 ohm load.

As for the resistor question... It can be done BUT there are some reasons it SHOULDN'T:

     1.  Speakers aren't really purely resistive.  They actually have an IMPEDENCE, not  a resistance.  using a resistor may much with the frequency response of the driver.

     2.  The resistor will use up half of the power of your amp to that channel and dissipate that power as HEAT, rather than sound.

If you want to use the cheapy speakers, wire 2 per channel in series to give an 8 ohm load.  That way, each speaker per side will only "see" half of the amp's power output per channel.

dphirschler:
OK, I did make a mistake in my above post.  I corrected it.  As for the 4 ohm/8 ohm question, I think I am just gonna get an amp that can handle my 8 ohm speakers.  I have two or three in mind now.  That T-amp is looking good right now.


Darryl

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