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Old 24th November 2008, 07:15 PM   #1
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Default No Bottom E?

Hello Everybody,

I've just recently constructed a pair of loudspeakers, the old style floor standing 12" woofer/mid/tweeter box type, and I'm quite happy with them, except for one thing. After a few days, I noticed when I'm listening to a recording with an electric bass, the bottom E doesn't seem to be as loud as it should. Like James Taylor's "Carolina on my Mind", the bass player slams the low E about 30 seconds into the song, but it just sounds lightweight and hollow to me.

The speakers are built around Dayton's 12" Classic woofer, in a 3.8 cu. ft. enclosure, with a 4" wide X 6.3" long port. I made sure the boxes are air tight.

I played a bass guitar for several years and realized that the lower notes are louder because the strings are larger....simple laws of physics.

I'd like to play around with the length of the port, but I'm not sure which way to go.
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Old 24th November 2008, 09:43 PM   #2
simon5 is offline simon5  Canada
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You'd probably need a much longer port. OTOH that classic Dayton woofer doesn't have much xmax so be careful.
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Old 25th November 2008, 11:07 AM   #3
sreten is offline sreten  United Kingdom
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Hi,

Tuning seem fine for 40Hz, but lower tuning is possible.

Your problems may relate to baffle step compensation.

For a typical 3-way the bass drivers needs to be ~ 4dB more
sensitive than the midrange and treble for even tonal balance.

/sreten.
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Old 25th November 2008, 03:08 PM   #4
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The boxes are pretty wide....18 inches. Do I still need BSC?

~~John~~
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Old 25th November 2008, 04:06 PM   #5
sreten is offline sreten  United Kingdom
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e.g. : http://www.t-linespeakers.org/tech/bafflestep/

and : http://www.tolvan.com/edge/

also : http://sound.westhost.com/bafflestep.htm

/sreten.
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Old 25th November 2008, 04:36 PM   #6
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I did build a baffle step correction circuit that I incorporated into my amps, and it works well. (I believe it sounds better than physically padding the tweeter). I'm (not totally) happy with the quality/quantity of the bass response. It's just that the bass seems to drop out around the low E frequency of an electric bass. I find that strange, considering the size of the woofer and enclosure.

Click the image to open in full size.
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Old 25th November 2008, 06:01 PM   #7
simon5 is offline simon5  Canada
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Default Re: No Bottom E?

Quote:
Originally posted by TubeHead Johnny
The speakers are built around Dayton's 12" Classic woofer, in a 3.8 cu. ft. enclosure, with a 4" wide X 6.3" long port. I made sure the boxes are air tight.
Are you sure it's 3.8 cu.ft internal net ? If it's more like 3 cu.ft internal net then you'd lose a few dBs at 40 Hz.

If yes, your tuning "seems" fine, as sreten said. It could be a room issue. Try moving the woofers around the room, or try it in another room.

Is your ceiling about 7 feet high ? Is your woofers approximately 7 feet from the wall ? Try positioning it around 14 feet from a wall to boost ~40 Hz.

I hope it will work...

Good luck !
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Old 25th November 2008, 11:26 PM   #8
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Quote:
Are you sure it's 3.8 cu.ft internal net ?
Inner dimensions are 30" X 16.5" X 14" = 6930 / 1728 = 4.01 cu. ft. Minus all the bracing, xo parts and the speakers....3.8 cu. ft. would be a safe estimate.


Quote:
Is your ceiling about 7 feet high?
Actually, the ceiling is more like 10 feet (It's an old hotel suite). I thought moving a speaker CLOSER to the wall would improve bass?
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Old 26th November 2008, 07:19 PM   #9
simon5 is offline simon5  Canada
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Quote:
Originally posted by TubeHead Johnny
Actually, the ceiling is more like 10 feet (It's an old hotel suite). I thought moving a speaker CLOSER to the wall would improve bass?
Yes, moving the subwoofer closer to a wall would enable it to play louder, and moving it in a corner will add even more bass.

OTOH, room dimensions can cancel and boost some frequencies relative to others.

You can look at this document to have an idea :
http://www.padrick.net/LiveSound/CancellationMode.htm

That's why I suggest you to try another room or move the speakers around to be sure, since your tuning seems perfect to play Low E, if we talk about the same 40 Hz low E.
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Old 26th November 2008, 09:22 PM   #10
PB2 is offline PB2  United States
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Obvious, but did you check that the woofers are in phase?

What are you driving them with?

Do you have a crossover schematic?

Have you checked the port tuning frequency?

Pete B.
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