4ohm speaker receiver question

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videodrone83

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So I still have been holding onto my Klipsch Ultra 5.1 system that was made for the computer but the sub has finally went dead on me

My question is the satellite speakers are rated for 4ohm and here are the specs on them

FTC Rated per Satellite: 60 w/channel @ ≤ 1% THD, 100Hz - 1KHz (Note: all channels driven)
FTC Rated Subwoofer: 170 w @ ≤ 3% THD, 40 - 100Hz
Maximum Burst Power*: 500 w

My plan was to just use 2 of the speakers and the center channel for living room setup and just buy a new sub and receiver.

http://www.bestbuy.com/site/denon-7...iver/3800036.p?id=1219093902408&skuId=3800036

This receiver does 140 watts per channel. Do you think I will realistically have any issues running 4ohm speakers on this?
 
Maybe. It isn't rated to work with 4 ohm speakers, and doesn't have a current limiter for it. You will probably be fine if you keep your volume levels moderate, but no guarantees.
 
It is highly likely that such a receiver would blow the speakers before going into overcurrent protection. But yeah.. no guarantees.

Your Klipsch's built-in amp could probably be fixed with a couple capacitor replacements if you or a friend can do some basic troubleshooting + soldering. Parts cost would likely be under $10 even w/ shipping from Mouser or similar. (This is not DEFINITE - it could be more than just caps - but most likely it's just caps.)
 
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No.

This amp is rated for a 6 ohm load at the lowest. You should not attach 4 ohm speakers to it.

Also, those speakers are so small you could get an amp rates for 80WPC and be more than fine.
 
Zangmonkey said:
This amp is rated for a 6 ohm load at the lowest. You should not attach 4 ohm speakers to it.
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It isn't that simple. Amplifiers have a current limit, a voltage limit, and a power limit (which is a combination of voltage and current but also has additional factors like the size of the transformer which are actually based on power). You can generally pick any impedance speaker you want as long as it never exceeds these limits in the way you use it (e.g. the input signal + gain you set it to).

Picking a lower impedance speaker means you will hit the current limit (potentially putting the amp into protection) sooner/easier. You'll generally be able to get at least half the rated power if you use a 4 ohm speaker on an amplifier designed for 8-ohm loads. Remember - whenever the output voltage is not at maximum (which is almost all the time, even with the max low-distortion output), the output transistors themselves are adding impedance of their own, meaning your amplifier only sees the impedance of the load when the transistors are fully switched on, which again is almost never at max volume and absolutely never at lower volumes. Additionally with some types of Class D amplifiers, changing the impedance of the load will mess with the output filter inside the amplifier and could cause distortion. But we're not talking about a Class D amplifier here.

To put it simply, a traditional amplifier (Class A,AB,B,C) takes a voltage and applies it to the speaker + a variable resistor (the output transistors). If you're not running full output power, your output transistors are never fully open, and your amplifier never actually sees the 4 ohm load.

Is it a good idea? Not particularly. But your statement is absolute and as such you are not quite correct. But I wouldn't buy such a receiver for this purpose, so I agree with you on that. I would probably risk it if I already had the receiver, though.
 
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amp doesn't state 4 ohm stable, if you were to put two speakers on each channel you could wire them in series to make it 8 ohm, which would work with your amp.
 
lilfiend said:
amp doesn't state 4 ohm stable, if you were to put two speakers on each channel you could wire them in series to make it 8 ohm, which would work with your amp.
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I have run 1,5 ohm load on a regular Yamaha AX-590 which is rated for 6 ohms without problems. It's all about how the amp stage is designed and how sensitive the protection circuits are.
 
I think the key to remember here is that we are talking about dinky little speakers from a set of Klipsch 5.1 computer speakers. The reasons why a set of full-sized 4-ohm speakers might not be the best fit don't necessarily apply in this case.
 
GotNoRice said:
I think the key to remember here is that we are talking about dinky little speakers from a set of Klipsch 5.1 computer speakers. The reasons why a set of full-sized 4-ohm speakers might not be the best fit don't necessarily apply in this case.
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An ohm is an ohm.
 
Unless the amplifier is a total joke (i.e. some joke built in an integrated circuit) it usually handles 4 ohm loads easily. The rated power does not mean the amp can't handle lower loads.

If it's a hifi amplifier it will have no problems running 4 ohms in 99,9% of cases. Some pioneer amps for example have super sensitive protection circuits which shut the power stage immediately even though the power supply would have plenty of oomph available.
 
GotNoRice said:
Do you actually understand what impedance means, and in what context it is significant from the perspective of the amplifier? Your responses would appear to indicate that you do not.
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Yes, and if the OP wants to learn about power delivery and amp stages he didn't express it in his question.

He asked if it was fine to put his dinky 4-ohm speakers on an amplifier which doesn't explicitly handle that load.

It might work, but OP should not do it.


B00nie said:
Unless the amplifier is a total joke (i.e. some joke built in an integrated circuit) it usually handles 4 ohm loads easily. The rated power does not mean the amp can't handle lower loads.

If it's a hifi amplifier it will have no problems running 4 ohms in 99,9% of cases. Some pioneer amps for example have super sensitive protection circuits which shut the power stage immediately even though the power supply would have plenty of oomph available.
Click to expand...


Any modern hifi amp will have protection circuit and should shut down the amp in the event that its current is too high. That doesn't mean OP should do this.
Get speakers that are rated for the proper load. It's not like his Klipsch speakers are all that great or expensive to replace with proper equipment.
 
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