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Topic: Tonal improvement-8 ohm vs 4 ohm speaker on SS amp? |
Steve Lipsey
From:
Portland, Oregon, USA
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Posted 11 Jul 2014 1:48 pm |
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I remember reading somewhere that using an 8 ohm speaker on an rated at 4 ohms actually sounded better (along with cutting the power (roughly by half).
Supposedly the frequency response curve was improved somehow, and the amp was fine with the higher impedance. (in fact, SS amps are OK with infinite impedance, i.e., no speaker, unlike tube amps)
Anyone know the actual story on this?
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https://www.lostsailorspdx.com
Williams S10s, Milkman Pedal Steel Mini & "The Amp"
Ben Bonham Resos, 1954 Oahu Diana, 1936 Oahu Parlor |
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Glenn Uhler
From:
Trenton, New Jersey, USA
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Posted 11 Jul 2014 2:59 pm Infinite impedence
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As you said, the SS amp was fine with the higher impedence, and likewise, with infinite impedence. But if I remember correctly, "no speaker" is _zero_ impedence, and not recommended with any amp, although a tube amp might tolerate it.
Hopefully, one of our amp techie members will chime in.
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1974 Marlen S-12 1968 Tele 1969 Martin D-35H |
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Steve Lipsey
From:
Portland, Oregon, USA
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Posted 11 Jul 2014 4:31 pm
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Actually, no speaker is infinite impedance. SS amps are OK with this. Tube amps need a speaker or they spontaneously combust...
Still looking for answer re the actual question, which was about tonal comparison between matched impedance or higher impedance...
_________________
https://www.lostsailorspdx.com
Williams S10s, Milkman Pedal Steel Mini & "The Amp"
Ben Bonham Resos, 1954 Oahu Diana, 1936 Oahu Parlor |
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Jim Priebe
From:
Queensland, Australia - R.I.P.
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Posted 11 Jul 2014 7:03 pm
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Steve
I think what you read was more of an opinion than a fact!
Any difference would more likely be from differences on the speaker itself (cone,surround etc.) and a host of other variables (wind direction, floor material, wall paint, what they ate last night etc. - kidding).
Seriously NOT the resistance measurement of the voice coil. At the exact same volume setting on the amp the db output would be different (maybe not exactly 1/2 but) that would effect the ear comparison for a start.
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Priebs GFI ('09)Short-Uni10. GFI ('96)Short-Uni SD11. ('86)JEM U12
www.steelguitardownunder.com |
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Steve Lipsey
From:
Portland, Oregon, USA
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Jim Priebe
From:
Queensland, Australia - R.I.P.
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Posted 12 Jul 2014 12:25 am
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Steve
| Quote: |
I remember reading somewhere that using an 8 ohm speaker on an rated at 4 ohms actually sounded better (along with cutting the power (roughly by half).
OK...search actually came up with something...folks I trust - Dave Grafe and Scott from Evans Amps - both say that running a higher impedance helps both low and high end response.... |
I read the post you mention (back when it was first posted) and it actually doesn't JUST say what you quoted. There are several other factors mentioned and things like "a more pleasing sound" could be seen as a pretty subjective statement. eg. I tried an 8 ohm EV (M12L) versus a 4 ohm one on a Peavey rated for a 4 ohm load and the (8's) sound just seemed more subdued (volume and tone) IMHO, but I'm sure other speakers would behave differently depending on their construction. Pretty hard one to generalise on.
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Priebs GFI ('09)Short-Uni10. GFI ('96)Short-Uni SD11. ('86)JEM U12
www.steelguitardownunder.com |
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Dave Grafe
From:
Hudson River Valley NY
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Posted 13 Jul 2014 12:08 am
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What you are talking about is known as "damping factor" - the ratio between the amplifier's output impedance and the impedance of the load it is driving. As the load impedance rises the amplifier's ability to tightly control the movement of the voice coil in the gap increases, minimizing cone bounce-back and supsension resonance, yielding lower THD and tighter, cleaner lows.
It is important to remember that many folk prefer the sound of a certain speaker specifically because of its distortion characteristics, so determining whether this sounds "better" remains a subjective thing, but it is cleaner.
Note that this does not apply to transformer-coupled - i.e. tube - amps, as the optimum load impedance is designed into the output transformer. |
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Dave Grafe
From:
Hudson River Valley NY
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Posted 13 Jul 2014 12:08 am
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What you are talking about is known as "damping factor" - the ratio between the amplifier's output impedance and the impedance of the load it is driving. As the load impedance rises so increases the amplifier's ability to tightly control the current flow through its output devices, and thus the movement of the voice coil in the gap, minimizing cone bounce-back and suspension resonance that commonly occurs at lower impedances, yielding lower THD and tighter, cleaner lows. Most high-end amps have significantly lower output impedances - and thus higher damping factors at a given load impedance - than the less expensive designs.
It is important to remember that many folk prefer the sound of a certain speaker specifically because of its distortion characteristics, so determining whether this sounds "better" remains a subjective thing.
Note that this does not apply to transformer-coupled - i.e. tube - amps, as the optimum load impedance is designed into the output transformer. |
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