# shouldn't a 4 ohm speaker be louder than a 6 ohm one?

Discussion in 'Archived Threads 2001-2004' started by Luke_Khuc, Apr 14, 2002.

1. ### Luke_Khuc Stunt Coordinator

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Hi,

I bought a bohlender center speaker which is rated at 4 ohm. I am trying to break it in and found out that my old jbl (6 ohm) sounds MUCH louder than the bohlender. I thought speakers with lower impedance will sound louder. These two speakers are connected to an old Sony receiver. Thx for your inputs.

2. ### Joe Casey Stunt Coordinator

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Speaker sensitivity (rated db output for 1W at 1 meter) measures 'loudness' of a speaker, nominal impedance does not. For example, a speaker rated at 90 db sensitivity will produce 90 db of sound when supplied 1W of power at 1 meter. That same single watt, when supplied to a speaker of 87db sensitivity, will effectively be half the 'loudness' at 1 meter (a doubling of power increases output by about 3 db).

3. ### Mark Larson Supporting Actor

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You thought it would be louder because your receiver sends more power to a 4 ohm load, right?
Well, your assumption is correct, but hearing doesn't work 'naturally'.
Your JBL's might have been more sensitive. A 3dB sensitivity increase equals a doubling in amp power.
So, if your 6 ohms were drawing 130 wpc, your 4 ohms (maybe) are drawing 160 wpc (it varies), but there is almost NO dicernable difference in loudness.
To get a doubling in loudness, you'll have to double the amp power. The hearing scale is logarithmic, so to double it, you'll have to increase power by a factor of 10. Thus, double of 100 watts is actually 1000 watts.
I'm not sure whether a 3 dB increase in sensitivity equals a doubling in perceived power (ie jump from 100 to 1000 watts), and will be happy if someone shed some light on this.

4. ### Matt Meyer Stunt Coordinator

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I think 10db is a doubling of "volume".
I think,
Matt

5. ### Wayne A. Pflughaupt Moderator Moderator

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6. ### Luke_Khuc Stunt Coordinator

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yup.. I just checked. the JBLs are 91dB while the Bohlender is 86dB.. Thx all.

7. ### Geoff L Screenwriter

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Luke,

Don't know if you have the whole set all round or what model, but how is the build quailty on the ~{New BG Center}~????

Geoff

8. ### Luke_Khuc Stunt Coordinator

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Geoff,
I HATE ubid.com!!! I was going to get a pair of 420s also, but I had soo many problems with ubid and ended up with the center only. (breathe Luke breathe. It's okay). Anyway, I have the center channel 220 and it's one heavy SOB. The build quality is like that of a tank. Its binding posts are a little bit smaller than ones on my Rotel 1095. One think I don't really like is the irremovable grill. I want to see what I've paid for ya know. There are several links you can look at.
From their website: BG 220 center and manual
Review from hometheaterhifi.com
You can check audioreview.com for more reviews.

9. ### Mike Veroukis Second Unit

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I'd just like to jump in here with a little comment. If you wish to make something twice as "loud" then you want a +6db in volume, not +3 or +10 like some have mentioned in this thread. If you want to test this out load something like Cool Edit Pro (or any good sound editor) and test it out yourself. In CoolEdit you can "amplify" using a db scale or a % scale. If you do a +6db you're amplifying by 100%, in effect doubling the volume.

I'm no expert of course, so someone please correct me if I'm wrong.

- Mike

10. ### Joe Casey Stunt Coordinator

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What I said was that a 3db gain in output requires a doubling in power, not that a 3 db increase in output is effective loudness doubling.

11. ### John Kotches Cinematographer

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THere are a few things here.

There is output power, that's 3dB for a doubling of output.

There is perceived loudness, which (generally speaking) requires 10dB for a doubling.

I'm not 100% sure on doubling SPL, and what the ramifications are.

Regards,

12. ### Luke_Khuc Stunt Coordinator

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13. ### Chris Tsutsui Screenwriter

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The difference is more subtle 3-4 meters while obvious from 0-1 meter. Sitting 50 meters and 51 meters will most likely sound identical to the human ear.

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