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.
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.
e.g. : http://www.t-linespeakers.org/tech/bafflestep/
and : http://www.tolvan.com/edge/
also : http://sound.westhost.com/bafflestep.htm
/sreten.
and : http://www.tolvan.com/edge/
also : http://sound.westhost.com/bafflestep.htm
/sreten.
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.
An externally hosted image should be here but it was not working when we last tested it.
TubeHead Johnny said:
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 !
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.
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?
TubeHead Johnny said:
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.
TubeHead Johnny said:
There's no cap in series with the midWoof? That is the small midrange driver ... correct? I hope you have it in it's own chamber.
Think about DC, or very low frequency, it goes to both the midwoof and woofer. You're wasting power at LF going into the midwoof, and probably overdriving it, to point out just one problem with that crossover.
Pete B.
TubeHead Johnny said:
I have no Idea how one would make connection of any sort.
How does Larger strings make lower notes louder?
More mass on the string allows the string to be tuned lower using higher tension.
Electric bass or guitar pickups are sensitive to string displacement and velocity. This generates a voltage across the windings, has nothing to do with "loudness".
The perceived loudness of the instrument has everything to do with the reproduction system and its ability to displace air, and very little to do with the string diameter.
If anything low bass equally loud with the rest of the audio spectrum is perceived as being less loud, and needs to be produced louder to have the same apparent loudness as the rest of the notes.
http://en.wikipedia.org/wiki/Equal-loudness_contour
I'm not to familiar with the Jamerson recordings, but a lot of older recordings really don't have much bass guitar information bellow 80Hz. Which makes sense as the 2nd harmonic of the open E lives in that range.
Because of placement constraints of pickups on electric stringed guitar and bass. The fundamental 40Hz is normally close to 10dB quieter than the 2nd harmonic.
http://www.till.com/articles/PickupResponseDemo/index.html
So its not surprising that you aren't hearing the 40Hz of his low E since, there probably isn't much there unless the engineer EQ'ed a lot of it into the recording.
TubeHead Johnny said:
Johnny,
If that's the DC300-8, in a 3.8cu ft box, with a round 4" by 6.3" port, then I'd say your tuning is more 31Hz than 40. At all but the highest volumes, the frequency response should be fair - but if you want more than 107dB, you'll find the driver hits xmax fairly easily between 40 and 50Hz.
If you shorten the port length to 2.5", then your tuning will go up to 40Hz. You'll have a bump in response (~4dB) near 50Hz, and the resonator (the port) should be handling all the 'E' notes easily. But then the bump in response may annoy you.
What are the other notes like when you're listening to bass? How about the mid-30's notes that Vic Wooten seems to be able to get? Your Daytons should be able to pump out 107dB down to 40Hz with no problems in a vented box configured like you've got at present.
I'd be looking somewhere other than the box layout. Have you tried it with and without the zobel or the baffle step circuit?
N.B. If it's not the DC300-8, then ignore...
TubeHead Johnny said:
Hi,
That seems to be your problem, hearing the bass roll off
of your mid/woofer as the mutual reinforcement of the two
drivers rolls off, i.e you have a big bump in the upper bass.
Try a series 1st order bass to mid ? add some L-pads ?
/sreten.P.S. EnABLing the ports will do nothing useful.
Re: Re: No Bottom E?
I haven't done a frequency response chart of your box/driver yet. However, according to WinISD, which is fairly accurate on these things, your box is tuned to 31 Hz.
With any given driver, at a box tuning of 31 Hz, you will be about 4 dB lower at 40 Hz than you will be if the box is tuned to 40 Hz. The lower the tuning below 40 Hz, the lower the response will be at 40 Hz.
So shorten the port to 2.5 inches and see what happens.
Cloth Ears said:
I haven't done a frequency response chart of your box/driver yet. However, according to WinISD, which is fairly accurate on these things, your box is tuned to 31 Hz.
With any given driver, at a box tuning of 31 Hz, you will be about 4 dB lower at 40 Hz than you will be if the box is tuned to 40 Hz. The lower the tuning below 40 Hz, the lower the response will be at 40 Hz.
So shorten the port to 2.5 inches and see what happens.
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