Is There A Way To Tighten Up the Sound Of A Woofer?

[Randy L]

Currently I have my Kappalite 3015LF's in a 5 c.f. cabinet tuned at 42hz.
Man they go deep--deeper than some of the cheaper 18" cabs mass marketted. I do notice, though, that the deep bass can sometimes sound a little "loose". Instead of a nice THUMP, it sometimes sounds more like a "BLOOOM." I wonder if it's more a placement issue than driver issue. Last night, I did have them placed in front of a 4' tall stage so I was getting some good boundary gain from it.

But if it is a driver issue, can I tighten up the bass by putting the 3015LF in a slightly smaller cabinet (3.5 or 4 c.f.) and tuning the vents a bit higher (maybe 48-52hz)? I'd prefer a solid deep hit than a "BLOOOOM." If I do tune the cabinet for a slightly higher frequency, I'd also be setting my low cut filter higher as well.

Incidentally, this is for recorded music, not live.

[awwnuts]

Currently I have my Kappalite 3015LF's in a 5 c.f. cabinet tuned at 42hz.
Man they go deep--deeper than some of the cheaper 18" cabs mass marketted. I do notice, though, that the deep bass can sometimes sound a little "loose". Instead of a nice THUMP, it sometimes sounds more like a "BLOOOM." I wonder if it's more a placement issue than driver issue. Last night, I did have them placed in front of a 4' tall stage so I was getting some good boundary gain from it.

But if it is a driver issue, can I tighten up the bass by putting the 3015LF in a slightly smaller cabinet (3.5 or 4 c.f.) and tuning the vents a bit higher (maybe 48-52hz)? I'd prefer a solid deep hit than a "BLOOOOM." If I do tune the cabinet for a slightly higher frequency, I'd also be setting my low cut filter higher as well.

Incidentally, this is for recorded music, not live.

How much power is each cabinet getting? Amplifier model and load impedance? What is your filter point and slope?

It could very well be a tuning issue, but I've found that you can make just about any speaker sound great with correct "external" settings and enough power. Hard distortion will cause a system to sound "loose" in the low frequencies. Your amp might need a better power source (straight to the elec. panel rather than a daisychain from other outlets).

[Randy L]

Each 8 ohm driver is fed by an amp delivering 700 watts RMS/ch @ 8 ohms. I rarely see a clip light engage. My Driverack PX filters out frequencies below 40hz, EQ pretty much flat, and I have crossover to the highs set at 100hz, feeding 2 QSC K10 powered cabs (which also never clip).
Gotta go check my crossover slope settings, but I think it's 24db.

[billfitzmaurice]

Instead of a nice THUMP, it sometimes sounds more like a "BLOOOM."

What does your RTA show for in room response?

[awwnuts]

When you say "sometimes it sounds...." do you mean on the same song? Is the room set up differently - say, more people?

I'm with Bill, I bet there is a room mode.

[billfitzmaurice]

I'm with Bill, I bet there is a room mode.

Maybe, maybe not, but whatever it is you can't fix the problem unless you first identify it.

[AMC]

If you don't have an RTA, and I'm guessing you don't as you didn't check it, then try walking around the room while it's playing. If it's a speaker problem, it will sound bad everywhere, if it's a room problem, you will find it gets good in places.

[Randy L]

It's not all the time, and I think it very well may be room modes. In fact, this last weekend, after noticing the "loose" bass, I did walk around, and it did sound much stronger in some parts of the rectangular ballroom and weaker in others.
My DRPX does have an RTA on it, but I haven't used it yet. Guess I should!

[Sydney]

It's not all the time, and I think it very well may be room modes. I

Did you tune it with impedance sweeps?
Have you done extensive listening outside?

[Randy L]

Impedance sweeps were obtained via WinISD7.x and nothing looked unusual. After putting the drivers in the cabinet, I did test them in my back yard, which opens to a large open field. Sounded very good out there.

That's what got me a little confused. I've had the drivers in the cabs for almost a year now. I noticed it last night about halfway into the party. Though my subwoofer amp wasn't clipping, I did turn the gains down from 2 O'clock position to 12 O'Clock and that stopped it. Bass was still very adequate so I left it there. I did recall hearing some looseness in the bass at a few events in the past, but as I look back, it was sporadic and I can't remember if it was always at the same venues. This is only a small percentage of the times I'm pushing the system. Either that, or I'm just not noticing it like I did last weekend.

Usually, I'm positioned behind the woofers, but last weekend, I was off to the side, out of necessity to event layout. No one has ever mentioned the bass sounding distorted or bad.

[Sydney]

Impedance sweeps were obtained via WinISD7.x .

I was under the impression that program ONLY models; and does NOT actually measure. Am I mistaken?

I did test them in my back yard, which opens to a large open field. Sounded very good out there.

So outdoors - did they sound Better ( than indoors ) and more importantly, did it have the same "loose" BLOOM as indoors?

[Randy L]

Sydney, yes WinISD only models as far as I can tell.

I never did notice that "Blooom" (lol) sound outdoors. The fact that I don't hear it all the time now has me thinking it might be the room acoustics. Otherwise, I'd hear it all the time, right?
This weekend, weather permitting, I'll set up my speakers outside again and give it a good run to see if I can recreate the sound.

[Sydney]

Otherwise, I'd hear it all the time, right?

That's was the process of elimination I had in mind.

WinISD only models as far as I can tell.

A model or simulation is a theoretical projection as opposed to an actual measurement. If the modeled driver parameters do not represent the reality - the model loses accuracy.
Because drivers have manufacturing tolerances they are not 100% precise devices. I've seen drivers that look identical; measure with enough variance to be unusable.
I used to tune cabs by ear - trying difference length ports and listening and repeating until I was satisfied. That is a slow somewhat tedious task.
It is much easier/faster/ more accurate to measure the actual T/S parameters and impedance curve and tune based upon these measurements.
Not saying that this is the situation - but acknowledging the possibility of mis-tuning, which should be evident outdoors ( without room effects ) as well as indoors

[wg_ski]

From my experience, with ANY subwoofer the "bloooom" sound results from just having the sub turned up too high in an attempt to get a bassy sound. You get too much just below the crossover frequency and not enough really low. And boomy rooms just make it that much worse. To have boosetd bass that sounds natural, the response needs to rise smoothly as frequency drops - i.e., no peak down to the lowest fundamental (41 Hz). Unfortunately, this isn't healthy for woofers or an "efficient" use of power/space/weight.

[AMC]

i.e., no peak down to the lowest fundamental (41 Hz). Unfortunately, this isn't healthy for woofers or an "efficient" use of power/space/weight.

Perhaps not, but I would agree that it sounds the best.