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AUDIO FORUMS >> General Discussion and Support >> Speaker efficency spec conversion?
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Message started by Sam S on 01/15/21 at 02:18:12

Title: Speaker efficency spec conversion?
Post by Sam S on 01/15/21 at 02:18:12

I am considering getting in line to buy a Rachel soon.
I have an old pair of Braun L 810 speakers (4 ohm) that have an Efficiency rating of 88dB with 2 watts input at 10 ft.

Does anyone know how to convert the above to the standard of 1 watt at 1 meter?

Thanks - Sam

Title: Re: Speaker efficency spec conversion?
Post by CAJames on 01/15/21 at 02:32:40

I think the rule of thumb is doubling the power = +3 dB SPL and doubling the distance = -6 dB SPL. And of course 10 feet = 3 meters so:

88 dB at 2 Watts at 3 M =

85 dB at 1 Watt at 3 M =

95 dB at 1 Watt a 1 M

Q.E.D.

Title: Re: Speaker efficency spec conversion?
Post by Lin on 01/15/21 at 04:05:39

Welcome to the forum Sam.

It is impossible to know exactly how much the 10 ft distance affected the spl in their measurements, but the 2 watts @ 4 ohms is = to 1 watt @ 8 ohms (2.83v).

Somewhere in the low 90s would be my guess at 1w/1m.
The ADS is spec'ed at 6 ohms nominal and 94dB = @92.5 1w/1m
Many companies show spl as 2 speakers in a room (=higher number) and a few measure 1 without room reinforcement (=lower number).

I like this spl calculator since it reflects my experience of levels in the typical small rooms in a house vs. a large performance venue that some pro audio calculators are aimed at.
https://myhometheater.homestead.com/splcalculator.html

Trying a combination is the only sure way to know if low power will work for each individual since we all listen to different music, in different rooms, and at different levels.

I'm completely satisfied with a 4 watt EL84 sep amplifier and 90 dB Fostex speakers in a 12' x 14' spare bedroom.

Title: Re: Speaker efficency spec conversion?
Post by DPC on 01/15/21 at 15:34:38

Nifty little SPL Calculator there Lin!

Thanks

Dennis

Title: Re: Speaker efficency spec conversion?
Post by Lin on 01/15/21 at 17:34:45

Hey Dennis, hope you are well. :)