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

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  • lorenmjones
    replied
    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.

    Originally posted by ngjockey View Post
    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.

    Leave a comment:


  • Mayhem13
    replied
    Re: Is there interest in a large three way "monkey coffin" collaboration?

    Originally posted by lorenmjones View Post
    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

    Leave a comment:


  • ngjockey
    replied
    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.

    Leave a comment:


  • lorenmjones
    replied
    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....

    Originally posted by Mayhem13 View Post
    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.

    Leave a comment:


  • Mayhem13
    replied
    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.

    Leave a comment:


  • Mayhem13
    replied
    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.

    Leave a comment:


  • rpb
    replied
    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.

    Leave a comment:


  • lorenmjones
    replied
    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.

    Originally posted by JasonP View Post
    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.

    Leave a comment:


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

    Originally posted by lorenmjones View Post
    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.

    Leave a comment:


  • lorenmjones
    replied
    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....

    Originally posted by Jay1 View Post
    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

    Leave a comment:


  • lorenmjones
    replied
    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.

    Click image for larger version

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    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?

    Originally posted by jhollander View Post
    Reading the graph it's -7 to get flat at 20 hz.

    Leave a comment:


  • Jay1
    replied
    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

    Originally posted by lorenmjones View Post
    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.

    Leave a comment:


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

    Here's a pic of a 3 way with the raw driver responses. The low woofer response is not accurate below 80 hz due to the test enclosure
    Attached Files

    Leave a comment:


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

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

    Leave a comment:


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

    BDS puts the -3db of baffle step at 150 and starting at 300.
    Here is a BDS graphClick image for larger version

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    So perhaps we lose a couple db from the woofer and a couple db from the mid? I understand baffle loss if it occurs in the middle of the passband of a midbass in a 2 way. I don't clearly understand how it is managed if it occurs in the midst of the crossover region.

    Originally posted by jhollander View Post
    Where are you thinking the baffle step is going to drop the woofer sensitivity to?

    Leave a comment:

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