Bob:
I never noticed that before, but my guess would be that due to the much
higher power output when using a lighter impedance load, the destortion
rating would naturally be higher...the more power put out, generally the
more distortion or at least the distortion rating or values increase.
For an amp putting out 100 watts at 8 ohms the destortion rating is a
certain amount, and an amp putting out 100 watts at 4 ohms would likely have
the same ratings or close to them.
A 100 watt amp at 8 ohms, running into a speaker rated at 4 ohms, and
therefore putting out something close to double the power that it would at 8
ohms, the destortion would increase by a significant factor.
Remember, that an amp is usually rated at a certain load and most home audio
amplifiers are not specifically designed to run at different loads.
this isn't a technical explanation but it is what I am guessing....when you
run an amp rated at 8 ohms impedance and put a 4 ohm load on it, the power
doesn't actually double either but its a generally accepted rule that it
nearly doubles.
Now, camercial audio amps, such as those used in PA systems are designed to
run on various loads usually ranging from 8 ohms to 2 ohms...and their
distortion ratings are not altered as the load decreases.
In fact, usually the specs claim that the distortion levels go down with the
lower load.
But of course, these amps have a switch on the back which sets the
particular impedance load that you will be using.
73
Colin, V A6BKX
----- Original Message -----
From: "Bob Tinney" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, September 05, 2007 2:50 PM
Subject: Re: OT stereo question
> Hi,
> I've been looking for a new home theater receiver for quite a while now
and
> looking through lots of specs. It seems that the lower the impedance of
the
> speakers attached to an amplifier, raises the reported level of
distortion.
> I'm not sure if this is a result of a matching problem or if it is simply
> because the amplifier will put out more power to a lower impedance load.
> Bob, [log in to unmask], K8LR
> Skype Name: bobtinn
> Life is full of challenges, that's what makes it interesting!
>
> ----- Original Message -----
> From: "Robert Clark" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Tuesday, September 04, 2007 10:19 PM
> Subject: OT stereo question
>
>
> Well I hope I did the right thing, ordered a Sherwood stereo receiver.
> Quewastion I ahve is, I have 2 pairs of speakers which are 6 ohms. Should
I
> bother with them, get matching transformers, or look for 8 ohm speakers?
>
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> Robert & Dreamer Doll ke7nwn
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10:36 PM
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