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when a speaker is labelled at 4-8 ohms... what does that mean, especially for the receiver/amplifier

C

changeling

New Member
Hello all,

I was thinking of buying some older speakers rated at 4-8 ohms. I don't know what it means when ohms are listed as a range like that. The speakers are American Acoustics American acoustics D555 OE. I am not sure the year of manufacture... I tried a Google search but did not find any info.

I had a pair of American Acoustics whose model I do not know, bought in 1990 or near there. They were different from the pair mentioned in the previous paragraph in that they were 3 way speakers, not 4. I gave them away and seriously regret that.. long story. I assumed wrongly I would like any modern speaker more than those American Acoustics I had had for a while. The "old" American Acoustics made music really come to life.

Back to ohm ratings - I first assumed that they had switches to change between 4 and 8 ohms, but I was wrong. Does it very with the type of signal sent from the receiver/amplifier?
 
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It mostly means the manufacturer is being honest. No speaker has a constant impedance. It will always vary, depending on the frequency it's reproducing.
 
Here's a reprint from a thread about American Acoustics.

American Acoustics Labs or AAL were made by the Mitec Group which later became MTX. These speakers were very popular in the Midwest in the 1980s as they were made in Winslow, IL. When the car audio boom hit, the company decided to focus on car audio rather than home audio; thus the popularity (or lack thereof) of MTX audio for the last 25 years in car audio. They are neither white van speakers nor high end. They were aimed at the general population, a step above most Japanese speakers of the 80s, but a step below AR, JBL, Polk and others of the day. I would compare them to Cerwin Vega in that they are extremely efficient and can play extremely loud.

https://forum.polkaudio.com/discussion/164399/american-acoustic-labs
 
eiraved said:
Here's a reprint from a thread about American Acoustics.

American Acoustics Labs or AAL were made by the Mitec Group which later became MTX. These speakers were very popular in the Midwest in the 1980s as they were made in Winslow, IL. When the car audio boom hit, the company decided to focus on car audio rather than home audio; thus the popularity (or lack thereof) of MTX audio for the last 25 years in car audio. They are neither white van speakers nor high end. They were aimed at the general population, a step above most Japanese speakers of the 80s, but a step below AR, JBL, Polk and others of the day. I would compare them to Cerwin Vega in that they are extremely efficient and can play extremely loud.

https://forum.polkaudio.com/discussion/164399/american-acoustic-labs
Click to expand...

I bought a new pair of speakers from Polk to replace my first pair of American Acoustics. Given, it was not a high-end Polk set of speakers, but I much preferred the American Acoustics. The Polk speakers sounded flat to me. I then bought a set of Klipsch speakers without test listening, and again found myself preferring the American Acoustics. Klipsch speakers sound muddy to me and did not have much clear treble or upper mid range. I then got a pair of Boston Acoustics from Craigslist. I first thought I liked them, but then found myself missing the treble and upper mid range I got from the American Acoustics. What ever the technical laboratory tests tells me, I often DON'T want to go with what they say. The American Acoustics, when I play live U2 performances, remind me more of the concerts I have gone to than Polk, Klipsch, and Boston Acoustics.
 
changeling said:
I bought a new pair of speakers from Polk to replace my first pair of American Acoustics. Given, it was not a high-end Polk set of speakers, but I much preferred the American Acoustics. The Polk speakers sounded flat to me. I then bought a set of Klipsch speakers without test listening, and again found myself preferring the American Acoustics. Klipsch speakers sound muddy to me and did not have much clear treble or upper mid range. I then got a pair of Boston Acoustics from Craigslist. I first thought I liked them, but then found myself missing the treble and upper mid range I got from the American Acoustics. What ever the technical laboratory tests tells me, I often DON'T want to go with what they say. The American Acoustics, when I play live U2 performances, remind me more of the concerts I have gone to than Polk, Klipsch, and Boston Acoustics.
Click to expand...

Different people have different opinions on speakers. All speakers have compromises, some speakers might sound more like live rock concerts, but less like jazz or classical music, etc.
 
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changeling said:
So, does that mean I can or cannot use these speakers with the Pioneer VSX-523?
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It largely depends on where it drops to 4 ohms and if there is a bad phase angle, all of which we don't know.
I assume you listen fairly loud (90+ dBs), so they are probably not a good match for an average home theater receiver, a better 2 channel amp like an integrated or separates would be a good idea.
 
eiraved said:
I would say no, but you may find differing opinions on that. The receiver will work, but it will be stressed at speaker impedances below 6 ohms.
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I used my previous set of American Acoustics for many, many years without problem. I do not know the model number on those, but given they both are American Acoustics, would it be OK to assume that the first pair of American Acoustics might have been rated 4-8 ohms? When I bought the speakers way back then, I am pretty sure the guy at the audio sales place said they were 8 ohm speakers.
 
opnly bafld said:
It largely depends on where it drops to 4 ohms and if there is a bad phase angle, all of which we don't know.
I assume you listen fairly loud (90+ dBs), so they are probably not a good match for an average home theater receiver, a better 2 channel amp like an integrated or separates would be a good idea.
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I have little idea how many dBs. It's fairly loud when I play stuff, but not nearly as loud as some of my neighbors play theirs. I live in a mobile home park.
 
Welcome to AK!
If you tend to listen to your Music loud then the fact that the speakers are going to dip to 4ohms means you run the risk of damaging your receiver as it will be straining to keep up with your speakers. In addition you are possibly running the risk of damaging your speakers as well if the receiver doesn't get enough power to them. If you are committed to those speakers then you should look at getting something capable of driving a 4ohm load.
 
changeling said:
I used my previous set of American Acoustics for many, many years without problem. I do not know the model number on those, but given they both are American Acoustics, would it be OK to assume that the first pair of American Acoustics might have been rated 4-8 ohms? When I bought the speakers way back then, I am pretty sure the guy at the audio sales place said they were 8 ohm speakers.
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It would not be safe to assume your first pair and second pair were the same impedance value.
However, as @opnly bafld stated earlier, it depends on where your speakers drop to 4 ohms and if there is a bad phase angle. Maybe your speakers never or rarely drop to 4 ohm impedance. So, you can take a chance and use the combination and maybe it will last for years, or maybe your receiver/speakers stop producing sound after a few weeks/months.
 
I appears that this receiver has a protection circuit.
Wouldn't this protect the receiver if the speakers' impedance drops to 4 ohms and causes a problem?
 
It will be fine. Worst case it gets too warm and shuts down. If you're going to be blasting for extended periods be sure the receiver has breathing room. That's good practice regardless of speaker load if one has a propensity to crank on it.

Ran Cerwin D9s, which specs I have say are 4 ohms, but some people say 8 ohms, some people say 4 - 8 ohms, on a Sony AVR for years. Hell, even left the 4/8 ohm switch on 8 ohms because it sounded so much better that way when cranked up. Nary a lick of problems in all the years I used the rig.
 
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