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Job of the Sub-Woofer

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Job of the Sub-Woofer

Postby Jim Reid » Fri Aug 13, 2010 1:24 pm

What Should A Sub-Woofer Do ?

It should increase the sound intensity of the lowest pipe sounds of the 16' rank
tones to be perceived at about the same loudness to the listener as the tenor
and soprano notes, or some music seems "better" if the low bass is even
heard a bit louder (depends upon taste, etc. of the organ player and seeming need
of the music). Same is absolutely true for a large number of tones from a
32' rank, pitch going on down to 16.35 Hz at lowest C pipe (equal tempered tuning).

OK, how much increase is needed: of course this varies with frequency of the tones.
Was completely examined and reexamined at the Bell Telephone Labs decades ago,
and re-examined again more recently. The following link shows the final "summary"
data released by Fletcher and Munson at Bell, and later reaffirmed well by Robinson and
Dobson. See:

http://www.webervst.com/fm.htm

This shows that for the loudness by a lowest notes of a 16' foot rank, the source must be generating
about 45 dB higher intensity (sound pressure level, or dB SPL) than a note at Middle C (261.63 Hz).
Musical scale note frequencies are listed at the following link, note Middle is C4, see:

http://www.phy.mtu.edu/~suits/notefreqs.html

Achieving the needed sound loudness increases as the notes go lower is the
task performed by the sub-woofer. Which woofer to use? Many opinions!

Some folks and music (theatre style) might want even more intense bass, at least a
few of the instrument ranks, than implied here.
Jim Reid
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Re: Job of the Sub-Woofer

Postby pwhodges » Fri Aug 13, 2010 2:46 pm

The Fletcher-Munson curves are irrelevant, because if the pipes have been recorded with a flat frequency response (which is the only rational thing to do), they should be replayed with a flat frequency response (which typically requires a sub-woofer). Then the ear can respond to the reproduced sound in the same way that it would respond to the original.

Of course, recording flat down to 16Hz requires careful choice of microphone, and careful processing to maintain that extended response.

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Re: Job of the Sub-Woofer

Postby toplayer2 » Fri Aug 13, 2010 6:16 pm

To clarify, the "Fletcher-Munson Effect" is the perceved decrease in the apparent relative loudness of bass frequencies, and to a lesser extent high frequencies, as the overall volume of the sound decreases. Early amplifiers often featured a "Loudness" switch which caused progressive boost to bass and treble as overall volume was decreased. This was intended to compensate for the Fletcher-Munson effect so that spectral balance seemed more natural at low listening levels. There has never been AFAIK any source recordings that were EQ'd in this fashion.

Getting back to the topic of subwoofers, those which are capable of flat power response down to 16 Hz are few and far between. The undisputed champion is the $29K Thigpen Rotary. The Trinity is probably the next best thing. With carefull shopping, I was able to buy a new one for $2200 delivered. If anyone wants to know where, send me a PM.

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Re: Job of the Sub-Woofer

Postby Eric Sagmuller » Fri Aug 13, 2010 8:02 pm

There are two right now on e-bay, buy it now for $1415, free shipping, factory refurbished.

I'm planning on using the Exodus drivers Clinton used, although two 15" LLT subs rather than two 21". The main disadvantage over the Trinity's is the much larger footprint. But the cost savings is considerable and I have the space.
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Re: Job of the Sub-Woofer

Postby toplayer2 » Fri Aug 13, 2010 8:12 pm

Eric Sagmuller wrote:There are two right now on e-bay, buy it now for $1415, free shipping, factory refurbished.

I'm planning on using the Exodus drivers Clinton used, although two 15" LLT subs rather than two 21". The main disadvantage over the Trinity's is the much larger footprint. But the cost savings is considerable and I have the space.


Don't see any at $1415, but there are two refurbs at$1614.99, still one hellofa deal!

Item# 170518070963

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Re: Job of the Sub-Woofer

Postby Eric Sagmuller » Sat Aug 14, 2010 9:21 pm

Strange. I think it must be the same ad. Just looked it up now and it shows expired but a price of $1899. I remember it did say something about the price only being good for a little longer. Looks like someone playing games.
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