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[MIKE Lynn]

   Simple Question , Which one wins ? Or mabey not so simple    Ill get to hear the McCauley next week , 2 of the driven by 2 powersoft K20's in a stadium so should be fun.

[Ivan Beaver]

   Simple Question , Which one wins ? Or mabey not so simple    Ill get to hear the McCauley next week , 2 of the driven by 2 powersoft K20's in a stadium so should be fun.

Short of a side by side- measured responses would be a place to start to compare.

Of course they do not give any indication as to the sonic quality

[John Chiara]

Short of a side by side- measured responses would be a place to start to compare.

Of course they do not give any indication as to the sonic quality

We all heard the McCauley a few years ago....it was LOUD...not sure I would want to listen to it for long..but please relate your experiences here.

[Ivan Beaver]

We all heard the McCauley a few years ago....it was LOUD...not sure I would want to listen to it for long..but please relate your experiences here.

I only have experience with the TH812 (and a good bit of it), but cannot relate it to the McCauley since I have not heard heard them side by side.

[Art Welter]

   Simple Question , Which one wins ?

Not very simple unless tested side by side.

https://soundforums.net/threads/1801-McCauley-M421-Quad-21-quot-Subwoofer

We can see that the M421 is -3 dB at 27 Hz, while the TH812 is -3 dB at 28 Hz.

The M421 uses four isobarically loaded 21" in what is generally referred to as a tapped horn. Isobaric loading reduces the cone area of four drivers to two drivers- each pair has more "push" but no more excursion or displacement than a single driver. The 21" used in the M421 are likely B&C21SW152, with  Sd of 1680 cm2, Xmax of 15 mm, so displacement 1680x 15 =25200cc x2 drivers =50,400cc.

IIRC, the 12" used in the TH-812 are no longer the same as pictured, but assuming the "long throw" 12" used have an Sd of 531 cm2 and an Xmax of 9 mm, 531 x 9 =4779 x 8=38,232cc displacement. If that assumption is correct, the M421 would win in output level by several dB if their cabinet volume were the same, but the TH-812 is larger, about 58 cubic feet compared to 42 cubic feet for the TH421. The cabinet size advantage could come very close to the displacement disadvantage.

If the 12" drivers used in the TH-812 have 15mm excursion (unlikely, but possible) displacement would total 63,720 cc, and the TH-812 would win in output by a fair margin.

At any rate, the TH-812 has smooth response in the 28-100 Hz range, the M421 does not.

Art

[Ivan Beaver]

Not very simple unless tested side by side.

https://soundforums.net/threads/1801-McCauley-M421-Quad-21-quot-Subwoofer

We can see that the M421 is -3 dB at 27 Hz, while the TH812 is -3 dB at 28 Hz.

The M421 uses four isobarically loaded 21" in what is generally referred to as a tapped horn. Isobaric loading reduces the cone area of four drivers to two drivers- each pair has more "push" but no more excursion or displacement than a single driver. The 21" used in the M421 are likely B&C21SW152, with  Sd of 1680 cm2, Xmax of 15 mm, so displacement 1680x 15 =25200cc x2 drivers =50,400cc.

IIRC, the 12" used in the TH-812 are no longer the same as pictured, but assuming the "long throw" 12" used have an Sd of 531 cm2 and an Xmax of 9 mm, 531 x 9 =4779 x 8=38,232cc displacement. If that assumption is correct, the M421 would win in output level by several dB if their cabinet volume were the same, but the TH-812 is larger, about 58 cubic feet compared to 42 cubic feet for the TH421. The cabinet size advantage could come very close to the displacement disadvantage.

If the 12" drivers used in the TH-812 have 15mm excursion (unlikely, but possible) displacement would total 63,720 cc, and the TH-812 would win in output by a fair margin.

At any rate, the TH-812 has smooth response in the 28-100 Hz range, the M421 does not.

Art

Art-the TH812 has used the B&C 12 TBX100 for all cabinets except the first couple of units.

The Xmax is 10mm on them with a power capacity of 1000 watts continuous  (the original drivers had a 700 watt continuous rating).

[Art Welter]

Art-the TH812 has used the B&C 12 TBX100 for all cabinets except the first couple of units.

The Xmax is 10mm on them with a power capacity of 1000 watts continuous  (the original drivers had a 700 watt continuous rating).

Then I remembered correctly, but the BC 12TBX100 has an Xmax of 9 mm (as I used in the displacement figures) and an Xvar of 11mm.

10mm is close enough for rock & roll ;^).

[Ivan Beaver]

Then I remembered correctly, but the BC 12TBX100 has an Xmax of 9 mm (as I used in the displacement figures) and an Xvar of 11mm.

10mm is close enough for rock & roll ;^).

I got the 10mm from the B&C spec sheet.  I got the 10mm from the B&C spec sheet.  Whats a millimeter or so between friends-------------

[Art Welter]

I got the 10mm from the B&C spec sheet.  I got the 10mm from the B&C spec sheet.  Whats a millimeter or so between friends-------------

You evidently have a different B&C spec sheet than mine ;^).
One silly millimeter made an ad campaign for Benson & Hedges 101..

[Ivan Beaver]

You evidently have a different B&C spec sheet than mine ;^).
One silly millimeter made an ad campaign for Benson & Hedges 101..

OK silly me.

I checked on their website before I replied and I guess I must have clicked on the wrong driver  

You win again   A lot going on right now and things on my mind.

[Kyle_Keating]

   Simple Question , Which one wins ? Or mabey not so simple    Ill get to hear the McCauley next week , 2 of the driven by 2 powersoft K20's in a stadium so should be fun.

Is the M421 an isobaric design? Meaning each pair of 21's are loaded front to back in the same baffle? Or is this a quad loaded horn?

[Art Welter]

Is the M421 an isobaric design? Meaning each pair of 21's are loaded front to back in the same baffle? Or is this a quad loaded horn?

Kyle,

The M421 is an isobaric tapped horn, photos of the isobaric chamber which contain the drivers loaded front to back are visible in the review linked in post #4.

Art

[Kyle_Keating]

Kyle,

The M421 is an isobaric tapped horn, photos of the isobaric chamber which contain the drivers loaded front to back are visible in the review linked in post #4.

Art

Thanks Art, I see it now, the left front drive has been removed in this picture. Is the chamber between the pair of drivers part of a horn or just an isolated volume?  And are the woofer in or out of phase in this alignment?
https://soundforums.net/attachment.php?attachmentid=1579&d=1308795096

[Art Welter]

Is the chamber between the pair of drivers part of a horn or just an isolated volume?  And are the woofer in or out of phase in this alignment?
https://soundforums.net/attachment.php?attachmentid=1579&d=1308795096

The isobaric chamber between the drivers is isolated from the outside atmosphere. The two drivers and the air in the isobaric chamber combine as one driver driving the tapped horn. The two drivers face the same direction and are wired in the same polarity, positive voltage makes both drivers go the same direction.

[Kyle_Keating]

The isobaric chamber between the drivers is isolated from the outside atmosphere. The two drivers and the air in the isobaric chamber combine as one driver driving the tapped horn. The two drivers face the same direction and are wired in the same polarity, positive voltage makes both drivers go the same direction.

Thanks Art

[drew gandy]

Thanks Art

And to add to Art's calculations comments earlier, isobaric systems tend to use up precious cabinet space (usually in the name of shrinking cabinet size, go figure) with the chamber of air and other parts necessary to fit the pair of drivers together.  That means that the Danley likely has an even greater "total cubic space" advantage than might appear on paper.  But, this is not to say that there aren't other advantages to the isobaric configuration.  McCauley may very well have gone with this configuration because they couldn't find (or manufacture) a single 21" with the parameters they wanted. 

[ProSoundWeb Community]