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

[Jay1]

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

That could be done. I just feel like if you're going to go for the big floor standing monkey coffin a 15" or even 18" woofer would fit the bill. PA460's under $100 :D

True enough on the baffle part.

Perhaps two variants are in order here from the outset if the one will not compromise the other. A shorter slightly smaller volume monitor variant with a rotatable baffle and a taller more tower style design with 25% more volume and a few hz of extra bass extension.

I would think if the baffle width were held constant both designs should require the same crossover. I don't know how the crossover is affected by the rotated baffle idea.

I again must defer to folks with crossover experience.

[lorenmjones]

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

This is baffle loss plus room gain. The deep LF isn't where the problem is. The problem is between 50 and 200 though. I think every room will be different in this regard, but I don't know how it all works out when trying to determine what the reference efficiency will end up being.



My big 15" 3 way for example with crossover voiced to match Dennis Murphy's Philharmonic 3's in his listening room. In my room Audyssey pulls out 3-6 db in most of the woofer's range. All that to say that I guess the room plays a huge role.

What crossover freq do you have on the Dino's? What do you think your final efficiency ended up being?

Reading the graph it's -7 to get flat at 20 hz.

[lorenmjones]

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

Ummm, yeah. That box gets huge and while the woofer can do like 118 db down to 35 hz in a 230 liter box, the rest of the system would not be able to keep up. You would have to switch to a CD on a horn and use a very robust prosound mid to keep up with that. The new mega systems that Erich referenced earlier in the thread are more along those lines....

That could be done. I just feel like if you're going to go for the big floor standing monkey coffin a 15" or even 18" woofer would fit the bill. PA460's under $100 :D

[JasonP]

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

The problem is between 50 and 200 though. I think every room will be different in this regard, but I don't know how it all works out when trying to determine what the reference efficiency will end up being.

My opinion is that there is no real, tangible, ideal solution for a target baffle step without knowing the size of room and where the speakers are going. However we can extrapolate from the extra large baffle size that in general full BSC will not be needed in the majority of listening conditions. If I was doing the design, I'd pick 3db of BSC. Here is my thinking. In this case, if the speaker was placed well out into a large room with little boundry boost, it will at worst sound a little thin. On the other hand, if its placed near wall with a significant amount of boundry boost, it will sound just a little warm. If you target -3db, you avoid the two worst case scenarios in my opinion. If you pick little or no BSC, you invite a horrible worst case scenario when the speaker is in the opposite position of how you planned. That's my two cents.

[lorenmjones]

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

I think you are probably right. I am going to mess around with some BDS and PCD sims tonight just to get an idea of whether the mid will have adequate sensitivity. I am quite sure that it will and if we don't need the sensitivity of the Fe200 mid I'm in favor of the Fe100 mid due to its smoother response.

My opinion is that there is no real, tangible, ideal solution for a target baffle step without knowing the size of room and where the speakers are going. However we can extrapolate from the extra large baffle size that in general full BSC will not be needed in the majority of listening conditions. If I was doing the design, I'd pick 3db of BSC. Here is my thinking. In this case, if the speaker was placed well out into a large room with little boundry boost, it will at worst sound a little thin. On the other hand, if its placed near wall with a significant amount of boundry boost, it will sound just a little warm. If you target -3db, you avoid the two worst case scenarios in my opinion. If you pick little or no BSC, you invite a horrible worst case scenario when the speaker is in the opposite position of how you planned. That's my two cents.

[rpb]

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

I'd try to make the eight ohm RS150p work. If the design needs to be pulled out from the wall, then just tell potential builders up front that it may sound a little warm, or that they may want some EQ available.

[Mayhem13]

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

There's a very practical way to alleviate some of that ragged baffle response from 250hz on down and combat the need for BSC.....make sure the woofer (a 15" does better here) is down low to the floor. You'll get the boundary gain AND avoid the 2-300hz floor ounce suck out. A robust mid that can do 250-300hz can still be placed high on the baffle without combing or spacial/timing discontinuity. It's an area where monitors fail terribly except for the nearfield. It's important to remember this when throwing around monitor type systems when in the company of monkey coffins. The designs aren't interchangeable and have specific purpose.

That being said, the DC380 still makes the most sense for extension, power handling, efficiency and costs.

[Mayhem13]

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

There's a very practical way to alleviate some of that ragged baffle response from 250hz on down and combat the need for BSC.....make sure the woofer (a 15" does better here) is down low to the floor. You'll get the boundary gain AND avoid the 2-300hz floor ounce suck out. A robust mid that can do 250-300hz can still be placed high on the baffle without combing or spacial/timing discontinuity. It's an area where monitors fail terribly except for the nearfield. It's important to remember this when throwing around monitor type systems when in the company of monkey coffins. The designs aren't interchangeable and have specific purpose.

That being said, the DC380 still makes the most sense for extension, power handling, efficiency and costs.

[lorenmjones]

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

Excellent point on having the woofer down lower and getting it essentially in 1/2 space between the baffle and the floor.

I think that is a great plan.

Why do you say a 15" does better in that way?

I am not against the DC380 sealed. I think an F3 of low 40's sealed does very nicely integrating with most rooms.

I don't see how it has better power handling or extension than the ST305 however. Even the efficiency as rated by Dayton is within 0.8 db, and WBCD calculates the ST305 to have 1/2 db higher efficiency than the DC380 based on T/S parameters.

Perhaps a pole on the woofer is in order....

There's a very practical way to alleviate some of that ragged baffle response from 250hz on down and combat the need for BSC.....make sure the woofer (a 15" does better here) is down low to the floor. You'll get the boundary gain AND avoid the 2-300hz floor ounce suck out. A robust mid that can do 250-300hz can still be placed high on the baffle without combing or spacial/timing discontinuity. It's an area where monitors fail terribly except for the nearfield. It's important to remember this when throwing around monitor type systems when in the company of monkey coffins. The designs aren't interchangeable and have specific purpose.

That being said, the DC380 still makes the most sense for extension, power handling, efficiency and costs.

[ngjockey]

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

This has been said before but, aside from baffle step, actually compounded, you should consider how the drivers are going tp sum. Way back, I showed a graph for a DS315/DS135. Now, that was shallower slopes and closer xo points than being discussed lately with the mid being more like filler but you'll notice it was always below the sum by a minimum of 2 dB. With steeper, further set slopes, you expose more of the mid and would need more sensitivity. That particular crossover was designed for a slanted baffle. I also planned a very low DCR Jensen toroidal inductor which gets expensive. The DS315 has a peak about 3 dB more than the ST305 at 150 Hz but it had half the power handling, which works out for a similar end result. If you trace the ST305 into FRD/ZMA files, you can use any of the "factory" DS series files and sim a suitable xo to see if you're in the neighbourhood. Guesstimate at the z-offsets until you get measurements. My guess would be that the ST305 would be close to -0.08 and I've guessed -0.021 for the DS135 before. Alternatively, you can get 500lb-bomb-close using the DS315 files and visually subtract 3 dB.

Getting more than a 3.9 to 4.3 mH coil, either 2nd or 3rd order, on the low pass looks to cut into that peak at 150 Hz, meaning maximum sensitivity probably at a higher xo than 300 Hz. Doesn't mean it will sound better or worse. Coil DCR will cut that down a dB or two as well. Can gain some back with oversized caps, say 75 to 90 uF. Zobels and tweeking cap/resistor values can help too. Have fun playing with it.

[Mayhem13]

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

Excellent point on having the woofer down lower and getting it essentially in 1/2 space between the baffle and the floor.

I think that is a great plan.

Why do you say a 15" does better in that way?

I am not against the DC380 sealed. I think an F3 of low 40's sealed does very nicely integrating with most rooms.

I don't see how it has better power handling or extension than the ST305 however. Even the efficiency as rated by Dayton is within 0.8 db, and WBCD calculates the ST305 to have 1/2 db higher efficiency than the DC380 based on T/S parameters.

Perhaps a pole on the woofer is in order....

The larger surface area of the cone compliments the change from 4pi to 2pi space as it naturally has better directivity lower in frequency.......something you can't overcome with excursion.

As to the actual in box response as opposed to sims.....not sure if WBCD figures in coil inductance as Unibox does but the Le will greatly impact the overall efficiency given the limited passband of the woofer in a three way.

Don't get me wrong, I'm not completely opposed to the ST305.........it's just a case of big toys for big boys when foot stomping floorstanders are the mission! Lol

[lorenmjones]

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

I was going to trace the ST305 tonight but the .pdf is protected. Any way to get around those protected files and trace the .frd data from them?

Also, with using traced data for the LF isn't it a problem that the Dayton spec sheets state very clearly that the data below 200 hz isn't valid due to measurement technique.

This has been said before but, aside from baffle step, actually compounded, you should consider how the drivers are going tp sum. Way back, I showed a graph for a DS315/DS135. Now, that was shallower slopes and closer xo points than being discussed lately with the mid being more like filler but you'll notice it was always below the sum by a minimum of 2 dB. With steeper, further set slopes, you expose more of the mid and would need more sensitivity. That particular crossover was designed for a slanted baffle. I also planned a very low DCR Jensen toroidal inductor which gets expensive. The DS315 has a peak about 3 dB more than the ST305 at 150 Hz but it had half the power handling, which works out for a similar end result. If you trace the ST305 into FRD/ZMA files, you can use any of the "factory" DS series files and sim a suitable xo to see if you're in the neighbourhood. Guesstimate at the z-offsets until you get measurements. My guess would be that the ST305 would be close to -0.08 and I've guessed -0.021 for the DS135 before. Alternatively, you can get 500lb-bomb-close using the DS315 files and visually subtract 3 dB.

Getting more than a 3.9 to 4.3 mH coil, either 2nd or 3rd order, on the low pass looks to cut into that peak at 150 Hz, meaning maximum sensitivity probably at a higher xo than 300 Hz. Doesn't mean it will sound better or worse. Coil DCR will cut that down a dB or two as well. Can gain some back with oversized caps, say 75 to 90 uF. Zobels and tweeking cap/resistor values can help too. Have fun playing with it.

[JasonP]

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

I was going to trace the ST305 tonight but the .pdf is protected. Any way to get around those protected files and trace the .frd data from them?

Also, with using traced data for the LF isn't it a problem that the Dayton spec sheets state very clearly that the data below 200 hz isn't valid due to measurement technique.

You can stitch an actual box response below 200 hz with the response above 200 using Response Modeler in Excel. If you have box dimensions, I could do that for you if need be.

[lorenmjones]

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

Understood. I wish there was an 8 ohm 15" with 8mm or so of xmax and the ability to do 30 hz or so in a vented box of say 130 liters or less. We could easily fit that kind of volume in this box by adding a little depth. Sadly the only woofers I know that exceed those criteria and have sensitivity over 90 db are AE TD series and the B&C 15BG100 both of which exceeed $300. I would even be more enthused about DC380 if it would work in a reasonable size vented box...but just for argument's sake here is the DC380 in 117L vented with Fb 21. It helps out with output and power handling down low below 50 hz. It doesn't look that bad actually. It gives the 107.5 db for 50 watts which is it's excursion limit. That is exactly the same output level the ST305 does in 100 liters with Fb of 30. The difference is the ST305 will handle 125 watts before it hits excursion limits putting it around 4 db better for max output.

I get what you are saying about the larger piston diameter having some degree of directivity to lower frequencies.

WBCD is JeffB's box simulator. He based it on Unibox. I have seen Jeff say it matches Unibox exactly FWIW.

Anyway here is the DC380 in the box mentioned above. What do we all think???

The larger surface area of the cone compliments the change from 4pi to 2pi space as it naturally has better directivity lower in frequency.......something you can't overcome with excursion.

As to the actual in box response as opposed to sims.....not sure if WBCD figures in coil inductance as Unibox does but the Le will greatly impact the overall efficiency given the limited passband of the woofer in a three way.

Don't get me wrong, I'm not completely opposed to the ST305.........it's just a case of big toys for big boys when foot stomping floorstanders are the mission! Lol

[ngjockey]

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

I've read that any measurements below 100 Hz are invalid from one of the acoustics treatment sites. The factory measurements are, or should be, standardized in a relatively "infinite baffle". In some cases, I've seen measurements on a 9" baffle for smaller drivers. What I was suggesting was just to help get a start, before you buy drivers, not a final design.