Subwoofers with 30hz performance.

Re: Subwoofers with 30hz performance.

Tim Duffin said:
I have heard the giant Mc 421 sub/horn thingy. Its loud and low, just not loud and low for its wieght. I know that the servodrive bt7 will do sub 30hz and the EAW sb2001/2 comes pretty close.

I think I would rather just have a stack of vertec dual 18's and be done with it.
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Tim,

In reality, the Basstech 7 has a knee around 32hz, and while you may be able to have useable output below 30hz, it is still falling off as any loudspeaker would do below tuning. With a sealed back chamber and horn loading, it's not as prominent as a vented box design.

The TH-50, TH-221, DTS-10 are the subs I'd go to today for a great combination of low end cutoff plus efficiency.

Best regards,

John
 
Re: Subwoofers with 30hz performance.

According to my measurements it doesn't. YMMV, they didn't give me any driver specs or recommended processing, so I was flying blind. IIRC I put the high pass at about 31Hz, so that puts the box -6dB at that point. -3dB is more like 36Hz.
 
Re: Subwoofers with 30hz performance.

Bennett Prescott said:
According to my measurements it doesn't. YMMV, they didn't give me any driver specs or recommended processing, so I was flying blind. IIRC I put the high pass at about 31Hz, so that puts the box -6dB at that point. -3dB is more like 36Hz.
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When measuring freq response (to see the extremes) there should be no high or low pass filters engaged.

If measuing overall performance, you could use the manufacturers filter specs-but be carefull if they recommend a boost down low or up high, as this can really throw off the max output capability of the box.

If you add a 10dB boost to extend the low freq (pretty common on some boxes) then you have to SUBTRACT that same 10dB from the max output-if you are talking about the low freq capability.

You don't get the boost for free.
 
Re: Subwoofers with 30hz performance.

Ivan Beaver said:
When measuring freq response (to see the extremes) there should be no high or low pass filters engaged.
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Like, duh. Winning.

I had to apply a (4.5dB?) boost at LF (35Hz? I don't recall exactly) to get this box to be "flat". That's pretty normal for a front loaded double 18" IMHO, but obviously the max output of the box needs to be adjusted to compensate.
 
Re: Subwoofers with 30hz performance.

John Halliburton said:
In reality, the Basstech 7 has a knee around 32hz, and while you may be able to have useable output below 30hz, it is still falling off as any loudspeaker would do below tuning. With a sealed back chamber and horn loading, it's not as prominent as a vented box design.
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Agreed. That McCauley sub is -10dB at 16Hz which means it's got a low cut-off probably near 12Hz. That's some serious infra sound. The BT7 doesn't have that kind of extension though it does do well within it's range.
 
Re: Subwoofers with 30hz performance.

Greg Cameron said:
Agreed. That McCauley sub is -10dB at 16Hz which means it's got a low cut-off probably near 12Hz. That's some serious infra sound. The BT7 doesn't have that kind of extension though it does do well within it's range.
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Greg,

In my book, -10db down at 16hz means the cutoff point has been passed already. Typically, the half power point of -3db is used to define the "cutoff". Well, at least when I'm comparing numbers.

FYI, the old Contrabass subwoofer has a -3db point of 16hz, and would hit 114db spl continuous at that point. That is closer to the mark, and in a pretty small package.

Best regards,

John
 
Re: Subwoofers with 30hz performance.

John Halliburton said:
Greg,

In my book, -10db down at 16hz means the cutoff point has been passed already. Typically, the half power point of -3db is used to define the "cutoff". Well, at least when I'm comparing numbers.

FYI, the old Contrabass subwoofer has a -3db point of 16hz, and would hit 114db spl continuous at that point. That is closer to the mark, and in a pretty small package.

Best regards,

John
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John,

I agree with you regarding LF cutoff points, though McCauly does not show a chart on the 421, the specs imply about 149 dB above 20 Hz, which would make 16 Hz about 136 dB (10 dB down from -3 dB), at that rate 12 Hz would be around 126 dB. That will still make your pants legs flutter.

That said, the Basstech 7 has a similar or even steeper rate of decline, in groups of four it drops from 142 dB at 30 Hz to 132 dB at 25 Hz, 10 dB in less than 1/3 octave.

Hard to tell the cutoff rate on the Contra, according to the spec sheet I have the -3 dB point is 15 Hz, it drops only one dB per 1 Hz from 17 to 15 Hz.

Tom Danley wrote that the maximum output was 112 dB at 14 Hz, I expect that is a +6 power figure.
Considering the graph stops at 15.8 Hz, I expect the Contra takes a nose dive below that point, perhaps you could tell us what it does below 14 Hz?

Art
 
Re: Subwoofers with 30hz performance.

John Halliburton said:
Tim,

In reality, the Basstech 7 has a knee around 32hz, and while you may be able to have useable output below 30hz, it is still falling off as any loudspeaker would do below tuning. With a sealed back chamber and horn loading, it's not as prominent as a vented box design.

The TH-50, TH-221, DTS-10 are the subs I'd go to today for a great combination of low end cutoff plus efficiency.

Best regards,

John
Click to expand...

Hi John,

I still don't think that 4 McCauley 421 thingys were less distorted at say 25hz than a group of 8 basstech 7's. I have heard both up close. While it may be true that the conventional driver sub has better specs on paper-- I don't see any specs regarding how distorted (in terms of non-linear excursion) it gets down around sub 30hz. The BT7 had almost no audible distortion at super low freqs.

Oh, and I almost forgot -- the BAG END infra system does get really low. Almost stupidly so. That is another option worth considering if low bass is what you are after.
 
Re: Subwoofers with 30hz performance.

Tim Duffin said:
Hi John,

I still don't think that 4 McCauley 421 thingys were less distorted at say 25hz than a group of 8 basstech 7's. I have heard both up close. While it may be true that the conventional driver sub has better specs on paper-- I don't see any specs regarding how distorted (in terms of non-linear excursion) it gets down around sub 30hz. The BT7 had almost no audible distortion at super low freqs.

Oh, and I almost forgot -- the BAG END infra system does get really low. Almost stupidly so. That is another option worth considering if low bass is what you are after.
Click to expand...
The BT7 horn cutoff with 8 cabinets is above 25 Hz. Although it has less than 1% distortion at 25 Hz, it is not designed for high output that low.
Under 10% distortion is pretty hard to hear below 100 Hz or so, as long as a (good) conventional speaker is kept below Xmax it should be below 10% distortion.

The Bag end infra systems go very low, but being a conventional speaker driven below Fs in a sealed box have little output down low. The processor limits output to keep the speaker within Xmax, therefore keeping distortion in check. As their hype, er spec sheet says:
“While the INFRASUB-18 will reproduce 8 Hz, it
is not audible nor does it have enough acoustical
power for you to feel it. The measurements
are taken at close range with sensitive instruments.
To achieve a flat response, as shown in
figure 1, full amplifier power is used at the lowest
frequencies and very little (<1 Watt) in the
upper frequency range.”

Good for home theater and low volume work, but not for heavy lifting.

Art
 
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