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View Full Version : Impedance and Sound Quality



UFO
11-30-2005, 10:47 PM
I think the best car system I ever had was with a pair of EPI M120b home speakers, laying on their backs in the hatch of a 1973 Plymouth Duster and powered by a 12W/channel Sanyo under-dash cassette deck (remember those?) and a cheapo 5-band graphic EQ unit with something like 15w/ch boost made by a company called Royal Sound.

I'm fairly certain those speakers were 8 ohm but they put everything I've had since to shame. Unfortunately they were huge particle board boxes that basically filled the car, and the woofer cones eventually just fell apart from temp/humidity extremes and age (I bought them in something like 1978, mind you.)

The question - finally: Does impedance affect sound quality in any way? IOW, is there any advantage in SQ between, say, a pair of 2 ohm speakers vs. 4 or 8?

Someone recommended that I try Adire Audio Extremis drivers for more raw power, but they're 8 Ohm speakers. I have two pairs of MB Quart PCE216s installed and I think at least one pair is fried. Can I swap in a pair of Adires and run two pairs of speakers having different impedances off of the same four-channel amp without destroying the amp?

Thanx,

<***>

squeak9798
12-01-2005, 10:00 AM
The question - finally: Does impedance affect sound quality in any way? IOW, is there any advantage in SQ between, say, a pair of 2 ohm speakers vs. 4 or 8?

No.


Someone recommended that I try Adire Audio Extremis drivers for more raw power, but they're 8 Ohm speakers. I have two pairs of MB Quart PCE216s installed and I think at least one pair is fried. Can I swap in a pair of Adires and run two pairs of speakers having different impedances off of the same four-channel amp without destroying the amp?


Yes.

However, you could not use the Adire Extremis on the MB Quart passives. And you would need a tweeter for the Extremis as well as some way to bandpass filter them (highpass and lowpass them).

engineerdude
12-01-2005, 10:30 AM
Speaker impedances are the load that your amplifier is carrying. Think about if you were skipping down a hallway, now if you skipped down that hallway holding 40 lb. dumbbells; your skip would turn into a run/walk wierd thing. The skip is the musical signal... the more you load it, the more distortion that can be played.

engineerdude
12-01-2005, 10:31 AM
Keep in mind that most amplifiers are capable of running at somewhat higher loads.. so the answer to your question is that impedance can affect SQ.. but probably only at extremes ( 4 ohm amp running at 1/2 ohm load),

adam71
12-01-2005, 06:50 PM
In all reality the the lower the resistance the higher the distortion which means the lower the SQ. This may or may not be audible.

azbass
12-01-2005, 07:15 PM
2 omh sounds better than 4 omh

adam71
12-01-2005, 07:17 PM
2 omh sounds better than 4 omh

2ohm is louder than 4 ohms but it does NOT sound better.

JimJ
12-01-2005, 07:17 PM
2ohm is louder than 4 ohms but it does NOT sound better.

1. Maybe it's louder, maybe it isn't.

2. Let's do an ABX test on that one :)

azbass
12-01-2005, 07:18 PM
he thought i was serious?

JimJ
12-01-2005, 07:18 PM
he thought i was serious?

Yeah...

adam71
12-01-2005, 07:20 PM
he thought i was serious?

You weren't?? I could have sworn you were since you didn't use any smileys.

adam71
12-01-2005, 07:23 PM
1. Maybe it's louder, maybe it isn't.

2. Let's do an ABX test on that one :)

What the **** are you talking about?? If you have a 2 ohm set of speakers they will receive twice the power that a 4 ohm speaker receives if it is the same amp. That is also taking into consideration that both sets of speakers have the same sensitivity.

JimJ
12-01-2005, 07:30 PM
What the **** are you talking about?? If you have a 2 ohm set of speakers they will receive twice the power that a 4 ohm speaker receives if it is the same amp. That is also taking into consideration that both sets of speakers have the same sensitivity.

Your statement...and like I said before, that's not always the case :) I know plenty of amps that will do the same power @ 2 ohms that it does at 4...or 4 and 8, or whatever. Both solid state and otherwise :)

As for the second part of what I said, if there were any links to credible ABX tests that show conclusively that a lower impedance sounds worse to the ear, I'd love to read them. If it's a measurable difference, but splits 50/50 to a group of listeners...it's all a bit academic.

adam71
12-01-2005, 07:35 PM
Your statement...and like I said before, that's not always the case :) I know plenty of amps that will do the same power @ 2 ohms that it does at 4...or 4 and 8, or whatever. Both solid state and otherwise :)

As for the second part of what I said, if there were any links to credible ABX tests that show conclusively that a lower impedance sounds worse to the ear, I'd love to read them. If it's a measurable difference, but splits 50/50 to a group of listeners...it's all a bit academic.

My first post said that it may or may not be audible so I didn't necessarily say it sounded worse. I just stated that the lower the resistance the higher the distortion.

squeak9798
12-01-2005, 09:52 PM
I just stated that the lower the resistance the higher the distortion.

in the amplifier.....which if it's within it's linear range will still likely be an inaudible amount :)

GSteg
12-01-2005, 10:48 PM
4.62 ohm sounds a lot better than 3.48ohm

:crazy:

4.01ohm is the best compromise between SQ and SPL.


True and tried!:blush:

squeak9798
12-01-2005, 10:55 PM
Well, and ofcourse that means all speakers sound absolutely horrid at resonance..........

OlogyAudio
12-02-2005, 12:05 AM
confusing noobs again are we? :p:

But seriously donít worry about it... Just make sure your amp is happy ;)

Also remember that series resistance will alter things more with a lower impd load... so if you are using those ****** 20-22awg stock wires that your car was wired with from the factory... this is an issue... otherwise don't worry about anything whatsoever... so long as your amp is happy (not driving too low an impd load) :)

adam71
12-02-2005, 02:43 AM
in the amplifier.....which if it's within it's linear range will still likely be an inaudible amount :)

I agree. I was more or less speaking in general. I said inaudible on my first post.

UFO
12-02-2005, 11:19 PM
Thanks for the feedback guys. So I can run a pair of 4 ohm speakers out of two channels of my amp, and a pair of 8 ohm speakers out of the other two, and there's nothing I have to set up with the amp? I'm assuming it would just be running the 4 ohm pair at a higher current than the 8 ohm, and therefore working the amp section that's powering the 4 ohms a little harder than the other?

And on the Adire Extremis speakers - if I were to stick them in the back panels as mid drivers and run all the treble through the MB Quarts in the front would I be wanting more mid-high and treble? With a sub installed would rear mids even buy me any additional punch for the money?