Is there interest in a large three way "monkey coffin" collaboration?

[bolland83]

Re: Is there interest in a large three way "monkey coffin" collaboration?

I haven't seen any recommendations for this woofer yet: http://www.parts-express.com/dayton-...oofer--295-320 Seems like it should perform pretty well for what we're trying to do here, and the price is certainly nice, what do you guys (the experts :D) think? Looks pretty good in 100 liters, port tuned to 25hz, f3/f10 30/20hz. Looks like it should hit 109db at 80 watts, not sure about xmax though as I'm still using winisd beta, the xmax is pretty low on this driver so that may make it a deal breaker.
Edit: It doesn't look too bad sealed in 100L either, f3/f10 43/23hz, could make for a dual use speaker with port plugs. Again, someone with a more advanced program will have to double check the how the excursion models.

[jhollander]

Re: Is there interest in a large three way "monkey coffin" collaboration?

You can lower the woofer to the floor and pick up of ~3 db from 2pi space. It works well with x-o points below ~500 hz as I think it gets muddy with high x-o plus low mounted woofer.

[rpb]

Re: Is there interest in a large three way "monkey coffin" collaboration?

I think I should mess around in BDS to help me see how that works out...

Post some graphs. Bass with infinite baffle vs bass with 15 x 42 baffle.

You should see the deep bass drop 6 dB. The drop starts around 1k for little boxes, and drops the full 6 dB by about 100 hz. The drop maybe starts around 400 hz on a bigger baffle. (Guessing 400 hz.) The deepest bass still should drop 6 dB relative to an infinite baffle. The midrange driver will show a drop in bass as well starting around 400 hz. That's OK, we plan to roll it off there anyway. Above that starting point, its sensitivity should be the specified half space value, so an 89 dB mid will be 89 dB in the 400 hz to 3k range. If the mid and woofer both start out as 89 dB, the woofer will drop to 83 dB down low. That would leave the mid too loud to match up with the woofers reduced output, unless it is padded down. But... if the woofer is placed near a boundary like the floor, or wall, or both, its output gets boosted back up. The exact amount is uncertain (uncertain to me anyway), but it could be more than 6 dB. Placing the woofer farther away from the boundaries reduces the amount of boost. Ideally, we don't want the woofers 100 hz to 400 hz range boosted more than 6 dB by the speakers position in the room. If it is boosted much more than 6 dB, we need a more sensitive mid, or two mids to match its boosted output. If the speakers are positioned 4 or 5 feet from the walls, and if the listening seats are not against the wall, a single mid is probably just the right sensitivity, especially if the woofer is about 20" off the floor. There is software (maybe JeffBs) that lets you check this for differing room sizes, and locations.

Baffle step compensation.... BSC... is just that. Its compensating for the reduced bass that is allowed by the baffle.

[lorenmjones]

Re: Is there interest in a large three way "monkey coffin" collaboration?

I think I should mess around in BDS to help me see how that works out...

It isn't really a concern due to the low crossover point and the width of the cabinet

[isaeagle4031]

Re: Is there interest in a large three way "monkey coffin" collaboration?

It isn't really a concern due to the low crossover point and the width of the cabinet

[lorenmjones]

Re: Is there interest in a large three way "monkey coffin" collaboration?

So essentially the need for BSC is taken care of in the mid to woofer crossover?

From my own little bit of experience so far, a target xover of around 300 and 3khz works out pretty well for drivers of this size. At that low of a crossover point, bsc won't be much of a concern really.

[lorenmjones]

Re: Is there interest in a large three way "monkey coffin" collaboration?

Maybe later tonight I can trace some frd and zma for them. I would love to be involved step by step in a PCD sim for this along with someone who knows what they are doing so I can learn a few things.

The ST 305 looks smoother than several of the other drivers that have been discussed.

A tower design would be better. My suspicion is that the woofer should be crossed pretty low. Maybe under 300 hz. If you have FRD, and zma files for these woofers, you should take a quick look and see what might be needed, and what ill effects a low x-over filter might have below 100 hz. A woofer, like the 12 Peerless, with a smoother response would probably be easier to filter, but maybe it's not a problem. The roller coaster midrange these 15" drivers have makes me wonder how they will actually sound.

[isaeagle4031]

Re: Is there interest in a large three way "monkey coffin" collaboration?

From my own little bit of experience so far, a target xover of around 300 and 3khz works out pretty well for drivers of this size. At that low of a crossover point, bsc won't be much of a concern really.

[rpb]

Re: Is there interest in a large three way "monkey coffin" collaboration?

A tower design would be better. My suspicion is that the woofer should be crossed pretty low. Maybe under 300 hz. If you have FRD, and zma files for these woofers, you should take a quick look and see what might be needed, and what ill effects a low x-over filter might have below 100 hz. A woofer, like the 12 Peerless, with a smoother response would probably be easier to filter, but maybe it's not a problem. The roller coaster midrange these 15" drivers have makes me wonder how they will actually sound.

[lorenmjones]

Re: Is there interest in a large three way "monkey coffin" collaboration?

I agree on the space thing. My preference skews toward tower esp if the extra volume yields improvements of efficiency and/or extension.

I like 15's a lot. I have them in my 3 ways and they are tremendous.

????

Unibox has always been my goto modeling program and been accurate to measured outdoor response but YMMV. Here's my excursion plot at 20w......no where near xmax and 100db at 30hz for a single drive unit. Add a pair and room gain and it's enough to chase anyone out of a room.[ATTACH=CONFIG]48175[/ATTACH]

Now ive always been practical where space is concerned and never really understood the whole stand mounted thing. In essence, we're taking up the same footprint wether a stand or enclosure so why waste the space and volume?.......just me of course.

There's always been the whoop a$$ factor of a 15" woofer over a 12 in my experience. They just do bass better to my ears. From a size standpoint, a 12" driver is certainly more practical........but a monkey coffin by definition isn't practical either so why dance around with it! lol Go for broke. If there was enough in the budget, i'd suggest TWO 15's per side. BAM!

[lorenmjones]

Re: Is there interest in a large three way "monkey coffin" collaboration?

Are those 15" or 12" woofers?

How tall are they?

This is something I'll be following. I've got a pair of 1974 Pioneer CS811s, and a project like this might be cool to compare the two.

[jwbohrer]

Re: Is there interest in a large three way "monkey coffin" collaboration?

This is something I'll be following. I've got a pair of 1974 Pioneer CS811s, and a project like this might be cool to compare the two.

[lorenmjones]

Re: Is there interest in a large three way "monkey coffin" collaboration?

Oh!! I modeled sealed. That's the difference.

????

Unibox has always been my goto modeling program and been accurate to measured outdoor response but YMMV. Here's my excursion plot at 20w......no where near xmax and 100db at 30hz for a single drive unit. Add a pair and room gain and it's enough to chase anyone out of a room.[ATTACH=CONFIG]48175[/ATTACH]

Now ive always been practical where space is concerned and never really understood the whole stand mounted thing. In essence, we're taking up the same footprint wether a stand or enclosure so why waste the space and volume?.......just me of course.

There's always been the whoop a$$ factor of a 15" woofer over a 12 in my experience. They just do bass better to my ears. From a size standpoint, a 12" driver is certainly more practical........but a monkey coffin by definition isn't practical either so why dance around with it! lol Go for broke. If there was enough in the budget, i'd suggest TWO 15's per side. BAM!

[lorenmjones]

Re: Is there interest in a large three way "monkey coffin" collaboration?

I double checked a couple times but will look again. Perhaps I have a parameter entered wrong. I always used unibox previously but have started using Jeff B's WBCD because of the filter section it includes. My understanding is that they should match exactly because Jeff used unibox as the basis for his. When I get home I'll post my FR and excursion plots and model conditions just to help sort it out.

????

Unibox has always been my goto modeling program and been accurate to measured outdoor response but YMMV. Here's my excursion plot at 20w......no where near xmax and 100db at 30hz for a single drive unit. Add a pair and room gain and it's enough to chase anyone out of a room.[ATTACH=CONFIG]48175[/ATTACH]

[Mayhem13]

Re: Is there interest in a large three way "monkey coffin" collaboration?

.

So the DC380 in 4 cubic feet would give a Q in the .6 range? I modeled it in 100 liters with walls covered (not stuffed) and it did a Q of .71 or so and had an F3 of 41 hz or something. It would work great from perspective of the response shape. I think it's main limiting factor is the limited xmax. 4mm is pretty meager and the output at 30 hz won't crack 100 db. Perhaps that is loud enough though. The drooping response would make crossover easy. I just wish it had a little more Xmax.

????

Unibox has always been my goto modeling program and been accurate to measured outdoor response but YMMV. Here's my excursion plot at 20w......no where near xmax and 100db at 30hz for a single drive unit. Add a pair and room gain and it's enough to chase anyone out of a room.

Now ive always been practical where space is concerned and never really understood the whole stand mounted thing. In essence, we're taking up the same footprint wether a stand or enclosure so why waste the space and volume?.......just me of course.

There's always been the whoop a$$ factor of a 15" woofer over a 12 in my experience. They just do bass better to my ears. From a size standpoint, a 12" driver is certainly more practical........but a monkey coffin by definition isn't practical either so why dance around with it! lol Go for broke. If there was enough in the budget, i'd suggest TWO 15's per side. BAM!