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Topic: Difference between 4 Ohm & 8 Ohm |
Johnie Helms
From:
Oklahoma, USA
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Posted 19 Jun 2015 10:30 pm |
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Hey y'all..
I'm wondering the main diff. When your reading the spec's, sensitivity and Frequency ratings when you read spec's on speakers.
Let's say we have a 4 Ohm 250 watt with a 98.2 dB and 52-2.9k rating Vs. 8 Ohm 350 watt with perhaps 100.8 or higher. And 42-4k (example)...
I know Ohm ratings are nominal but, it seems to Me that the later would be more efficient
And the amp would seem to run abit cooler..
Your thoughts.
Thanks
JH |
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Georg Sørtun
From:
Mandal, Agder, Norway
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Posted 20 Jun 2015 1:38 am
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In your example, an 8 Ohm 350 watt with (perhaps) 100.8[db] or higher, and a 42[Hz]-4k[Hz] freq range speaker, should on paper be more efficient than a 4 Ohm 250 watt with a 98.2 dB and 52[Hz]-2.9k[Hz] speaker ... given that they end up in cabinets that take the standard conditions speakers are spec'ed under into account.
First, how such specs are usually presented...
Ohm impedance: the speaker's nominal load on amp.
Watt energy: the maximum repeated bursts (music-peaks) energy the speaker can handle. (Note that continuous energy handling for speakers is usually 1/10 to 1/20 of their repeated burst handling).
Sensitivity: the (narrow center-band) audio output a speaker produces when drawing 1 (one) Watt from the amp. Measured in db at a standard distance - usually about 1 meter / 3 feet - in front of speaker.
Freq range: a speaker's frequency range - usually given with a +/- db scale (within +/-6db for instance) - when mounted onto a standard-sized baffle. Measured at a standard distance - usually about 1 meter / 3 feet - in front of speaker.
Of course, the basic specs are just that - "pretty basic", and only allows for rough sorting.
A speaker's distortion is usually left out - expect it to be somewhere in the 5% to 50% dist-range, and a speaker's size and cone-shape says a lot about its basic ability to react accurately to bursts, and also how it can be expected to spread sound-waves off center over each part of the frequency range.
Also, in practical use, take into account what type of amp that will be delivering the energy, and at what load it is designed to deliver the (required) energy. |
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Erv Niehaus
From:
Litchfield, MN, USA
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Posted 20 Jun 2015 7:50 am
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4 Ohms  |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 20 Jun 2015 8:09 am
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It all depends on the amp you're connecting... for solid-state amps, most of them put out a lot more power at 4ohms. Your example has almost 3dB difference between sensitivities... this could make up the difference in power when connected to SS amps. For a tube amp with 4 and 8ohm taps, the 8 will put out more power. Be aware that not all companies use 1w/1meter 1kHz for their sensitivity measurements. Also, 3dB is not that much... we can *barely* hear a 1dB difference.
Not knowing your exact application, it's going to come down to tone. Which one sounds better? Weight and price also come into play. If you can, try both blindfolded and take the one you like.
_________________
Too much junk to list... always getting more. |
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Dave Grafe
From:
Hudson River Valley NY
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Posted 23 Jun 2015 11:30 am
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| Quote: |
| Also, 3dB is not that much... we can *barely* hear a 1dB difference. |
Perhaps, depending on the listener and the environment, but bear in mind that while the nominal speaker impedance numbers are linear, dB scales are logarithmic, thus a gain of +6dB SPL represents a doubling of SPL delivered per volt. The wider frequency response suggests a more accurate driver as well, so if you want to run clean at volume the 8 ohm speaker is your friend. |
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Brad Sarno
From:
St. Louis, MO USA
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Posted 23 Jun 2015 8:29 pm
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| Erv Niehaus wrote: |
| 4 Ohms |
Doh, Erv beat me to it....
B |
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Erv Niehaus
From:
Litchfield, MN, USA
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Posted 24 Jun 2015 10:26 am
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