Here it is:
http://www.zaphaudio.com/BAMTM.html
THIS is the one I'm going to build - I've been hoping for a design with this driver combination for some time and now it's been done, and by the man himself. Even has options for integrated subs, my favorite.
Kudos John! Will he ever stop? I sure hope not.
http://www.zaphaudio.com/BAMTM.html
THIS is the one I'm going to build - I've been hoping for a design with this driver combination for some time and now it's been done, and by the man himself. Even has options for integrated subs, my favorite.
Kudos John! Will he ever stop? I sure hope not.
Hello,
Thanks for the comments. I've been busy with work a lot lately, so it's probably a good thing I got this project posted when I did. I don't have much extra time available for projects these days. I'll participate in this thread for a little while if anyone would like to discuss this project.
I just fleshed out the options a bit more. I've got a cad drawing showing the version with integrated 10" Dayton RS subs which I hope to post sooner or later with some usage details.
Thanks for the comments. I've been busy with work a lot lately, so it's probably a good thing I got this project posted when I did. I don't have much extra time available for projects these days. I'll participate in this thread for a little while if anyone would like to discuss this project.
I just fleshed out the options a bit more. I've got a cad drawing showing the version with integrated 10" Dayton RS subs which I hope to post sooner or later with some usage details.
Hi John,
I do have a few questions:
1) How was the crossover point selected? Was it to completely
avoid the break-up areas of the Dayton? Or...?
2) Would there be any special considerations if using one woofer as opposed to two? My listening room is currently my 12x10 bedroom and I was planning on a single woof, similar to the SEAS L18 design (sealed), with small stereo subs (see #4).
3) Would the Dayton RS150/180 be a workable woofer in this design, i.e., would the crossover require much modification?
4) Since I have a small-ish listening room, and will even when I move to an apartment (where the system will be in the living room but I will of course have neighbors to consider), I really can't see having sub drivers over 8 inches, so I'm wondering what might integrate well with the design - Peerless SLS? Or perhaps the Dayton SD215-88?
Thanks much.
I do have a few questions:
1) How was the crossover point selected? Was it to completely
avoid the break-up areas of the Dayton? Or...?
2) Would there be any special considerations if using one woofer as opposed to two? My listening room is currently my 12x10 bedroom and I was planning on a single woof, similar to the SEAS L18 design (sealed), with small stereo subs (see #4).
3) Would the Dayton RS150/180 be a workable woofer in this design, i.e., would the crossover require much modification?
4) Since I have a small-ish listening room, and will even when I move to an apartment (where the system will be in the living room but I will of course have neighbors to consider), I really can't see having sub drivers over 8 inches, so I'm wondering what might integrate well with the design - Peerless SLS? Or perhaps the Dayton SD215-88?
Thanks much.
sdclc126 said:
1) The primary goal was to clear the peak in the 3rd order harmonic distortion which would mean a crossover just under 2kHz. But, thanks to the capabilities of the Seas tweeter, I crossed over just under the 5th order harmonic, enough to decrease it's audibility a bit. I really pushed the tweeter to find out how low I could go. I actually crossed over at 1Khz which didn't work well. Not only did it distort audibly at medium levels, but the filter Q had to be very sharp to bring up the rolled off response. 1450 had no issues at high levels. I hope I didn't sacrifice any of my hearing during that experiment.
2) The driver combination could work ok with one DA175 and one 27TBFCG, but the crossover would have to be redesigned. Not only because of the lower needed tweeter level and single woofer impedance, but also because the tweeter would have a different response at the top of an enclosure rather than in the middle of an MTM.
3) Yup, total redesign. The RS series have a very peaky breakup. The DA175 has only mild breakup peaking, and it gets away with only two components and no notch filter. I think there's other designs out there with the RS180 and a Seas. Jon Marsh's Modula maybe?
4) Anything that fits in the lower comparment is fair game. There are many 8's that work well in 1 cu ft. But if you can fit the 10's in the budget, this layout may work for you. I do recommend external amplification in this usage.
Thanks for all the info. I'll stick with the design as-is (love the simple crossover), and as I already have a pair of Mach 5 10" subs I might as well use them - I'll just have to keep the gain down low for the sake of the neighbors. One of these days I've GOT to move out to the country.
I do have one other question - it's only indirectly related to this design, but have you ever considered open baffle/dipole? I am intrigued by the concept and have wondered how to do a "budget" version of something like the Linkwitz Orion. The reason this is somewhat relevant to the BAMTM is that it occurred to me that its driver compliment might make a workable OB top end (with appropriate crossover and equalization), and coupled to a dipole bass unit.
As I said this question may be a little off topic, but if you have any thoughts I'd be very interested in hearing them. OB/dipoles are tricky and complex (read expensive), especially with active x-over & amplification, and I don't recall reading anywhere if you've ever delved into that area.
Thanks again for the BAMTM - it is exactly what I've been looking for.
Hopefully I'll have a build to show off here early next year.
I do have one other question - it's only indirectly related to this design, but have you ever considered open baffle/dipole? I am intrigued by the concept and have wondered how to do a "budget" version of something like the Linkwitz Orion. The reason this is somewhat relevant to the BAMTM is that it occurred to me that its driver compliment might make a workable OB top end (with appropriate crossover and equalization), and coupled to a dipole bass unit.
As I said this question may be a little off topic, but if you have any thoughts I'd be very interested in hearing them. OB/dipoles are tricky and complex (read expensive), especially with active x-over & amplification, and I don't recall reading anywhere if you've ever delved into that area.
Thanks again for the BAMTM - it is exactly what I've been looking for.
Hopefully I'll have a build to show off here early next year.
John,
I too am interested in building a BAMTM, specifically the vented floorstander. Your drawing shows damping material in the upper 36" of the enclosure. Is this supposed to be whispermat/sonic barrier as you've used in some of your other designs? Also, where you show extra damping at the bottom, do you mean insulation only on the base or stuffing the last 8"?
Thanks for sharing your designs.
pete
I too am interested in building a BAMTM, specifically the vented floorstander. Your drawing shows damping material in the upper 36" of the enclosure. Is this supposed to be whispermat/sonic barrier as you've used in some of your other designs? Also, where you show extra damping at the bottom, do you mean insulation only on the base or stuffing the last 8"?
Thanks for sharing your designs.
pete
Dawaro - Post #7 - Not speaking for Zaph here, but IMO there would need to be no mods for a center channel, save for adding bucking magnets to the drivers if you have a CRT TV set. All you'd need to do is build three and tip one on its side for the center 
Unless it takes up too much space then maybe you could use the smaller 5.25" Dayton woofs, in which case a crossover mod might be necessary.
MuaDibb - Post #8 - Here's what Zaph says in his text for the BAMTM:
"Integrated sub- A floorstanding tower with the top 1 cu ft section sealed off can give you at least a cubic foot below to work with for other uses, primarily dual integrated subs. If the MTM+sub route is taken with 1 cu ft on the bottom, look no further than the Dayton RSS265HF in sealed or the RSS265HO vented and tuned to about 25-27Hz. Side mounted would work fine with 150Hz or lower active crossover. Needs a couple hundred watts each, not too expensive if you stick to prosound amps. I'd stick to external amps and avoid plate amps for this usage. These Dayton RS subs represent extremely high performance and great value. I use them myself and highly recommend them. For other options, simply look for something that will work in this enclosure size."
JasonB - Post #9 - Though I have no measuring equipment I can only say the Mach 5s seem to be very strong and capable subs, delivering deep yet clear low end on a par with the Peerless XLSs, drivers they were apparently designed to directly compete with. They are certainly competitively priced, except for the shipping cost from Canada (I purchased mine second hand here in the states). I suspect the Peerless have better motors and thus lower measured distortion, but audible? Don't know - personally for sealed subs without room correction my experience is there are more similarities than differences, but that's just me.
Unless it takes up too much space then maybe you could use the smaller 5.25" Dayton woofs, in which case a crossover mod might be necessary.MuaDibb - Post #8 - Here's what Zaph says in his text for the BAMTM:
"Integrated sub- A floorstanding tower with the top 1 cu ft section sealed off can give you at least a cubic foot below to work with for other uses, primarily dual integrated subs. If the MTM+sub route is taken with 1 cu ft on the bottom, look no further than the Dayton RSS265HF in sealed or the RSS265HO vented and tuned to about 25-27Hz. Side mounted would work fine with 150Hz or lower active crossover. Needs a couple hundred watts each, not too expensive if you stick to prosound amps. I'd stick to external amps and avoid plate amps for this usage. These Dayton RS subs represent extremely high performance and great value. I use them myself and highly recommend them. For other options, simply look for something that will work in this enclosure size."
JasonB - Post #9 - Though I have no measuring equipment I can only say the Mach 5s seem to be very strong and capable subs, delivering deep yet clear low end on a par with the Peerless XLSs, drivers they were apparently designed to directly compete with. They are certainly competitively priced, except for the shipping cost from Canada (I purchased mine second hand here in the states). I suspect the Peerless have better motors and thus lower measured distortion, but audible? Don't know - personally for sealed subs without room correction my experience is there are more similarities than differences, but that's just me.
Zaph,
Did you have the PE pre-fab cab in mind when you designed the integrated sub section? It almost looks like a perfect fit, save for the slightly shorter depth. Then it could be a modular, removable system a la the NHT Evolution. Also, I know you recommend prosound amps and not plate amps for this project, but I noticed that one of the BASH amps, thanks to their long and narrow proportions, would fit nicely on the back panel. Granted, it would be expensive to use two of those in stereo.
Do you have any thoughts on these ideas? Thanks a lot for posting the design. Keep up the good work!
Did you have the PE pre-fab cab in mind when you designed the integrated sub section? It almost looks like a perfect fit, save for the slightly shorter depth. Then it could be a modular, removable system a la the NHT Evolution. Also, I know you recommend prosound amps and not plate amps for this project, but I noticed that one of the BASH amps, thanks to their long and narrow proportions, would fit nicely on the back panel. Granted, it would be expensive to use two of those in stereo.
Do you have any thoughts on these ideas? Thanks a lot for posting the design. Keep up the good work!
sdclc126 said:
At this point, I've done at least 1 or 2 of just about every type of loudspeaker. There are some types however you aren't likely to find on my web site (yet) because I consider others to do them better than I do. Dipoles are one type of speaker like that. But, I guarentee there will be a dipole on my web site some day. It will be fully passive (and therefore budget oriented) because I don't want to own multi-amped speakers with an active crossover.
widman said:
Yes, whispermat or sonic barrier is the optimal damping material on top. In the bottom of the vented enclosure where I specify 8" thickness of damping, packed dacron fiber will work fine. This will absorb the lengthwise pressure node. Good observation, I should add that to the page.
coolkhoa said:
Actually, a PE box on the bottom would work fine for a modular sub. If you were going to use the 10" RS sub, you'd certainly want to glue the front baffle on solid or the sub will rattle the 4 "b-rex" bolts right apart from the high pressure. Also, when cutting the side opening, you'd have to figure out a way to remove the crossbrace inside to clear the woofer.
Likewise, a person could just use the PE box on top and build subs into stands below.
One quick edit: the power supplies in some plate amps tend to hum when close to massive woofer magnets. In a smallish enclosure where space is at a premium, it's hard to put some space between these. And naturally, if space is hard to come by, an external amp works better.
Thanks for another well worked out and well documented design..
Probably several things I would want to ask eventually, but the first one is related to the comments of power handling...
I'm curious at about what power/SPL level do the "problems" set in.. i.e. the compression in the woofer you mention in the writeup when you reach the limits in driving this particular design.
I'm trying to get a feel for overall power handling and dynamic range... and at what point would the diistortion and compression start to become an issue...
Probably several things I would want to ask eventually, but the first one is related to the comments of power handling...
I'm curious at about what power/SPL level do the "problems" set in.. i.e. the compression in the woofer you mention in the writeup when you reach the limits in driving this particular design.
I'm trying to get a feel for overall power handling and dynamic range... and at what point would the diistortion and compression start to become an issue...
John,
after the nice high-end ZD5 speaker, it's good to see you back to where your roots lie .
In this design you chose to cross the tweeter at an unconventionally low frequency. The nasty breakups of the Daytons of course gave reason to try it out.
In other models with this same (very robust) tweeter you used a higher crossover point. The partnering drivers were all better behaved in the higher mids than the Daytons.
Knowing that the low crossover point works so well in this combination, do you now think that a lower crossover point might also have been good option in other designs you've previously done? What do you consider to be the pros and cons of such low crossovers?
Thank you very much, and keep up the wonderful job you are doing for the DIY community!
Regards,
Martijn
after the nice high-end ZD5 speaker, it's good to see you back to where your roots lie
.In this design you chose to cross the tweeter at an unconventionally low frequency. The nasty breakups of the Daytons of course gave reason to try it out.
In other models with this same (very robust) tweeter you used a higher crossover point. The partnering drivers were all better behaved in the higher mids than the Daytons.
Knowing that the low crossover point works so well in this combination, do you now think that a lower crossover point might also have been good option in other designs you've previously done? What do you consider to be the pros and cons of such low crossovers?
Thank you very much, and keep up the wonderful job you are doing for the DIY community!
Regards,
Martijn
Project Update....
I'm in the progress of building this design with a twist. Being very new to DIY speaker building, I am always looking to learn and understand as much as possible with this hobby. With this design, I am building a 2 cu ft tower speaker, with removable baffle and movable shelf braces. My intentions are to try out a few of the different enclosure recommendations. I will be able to do the 1 cu ft sealed, 1.5 cu ft sealed, and the 2 cu ft selaed and ported. I am hoping to understand what sounds best to me in my listening room.
The attached pictures show a completed previous project, rs150 MTM by CJD with the rs28a tweeter for comparison that I use for my HT.
I only have 4 screws in the baffle (will add more) but the test run so far has been very pleasing. I am by no means an audiophile, so I will not try and wax poetic, but I am very excited about this budget design. I must say, the seas tweeter sounds awesome, very similar to the rs28a and even $15 cheaper.
I'm in the progress of building this design with a twist. Being very new to DIY speaker building, I am always looking to learn and understand as much as possible with this hobby. With this design, I am building a 2 cu ft tower speaker, with removable baffle and movable shelf braces. My intentions are to try out a few of the different enclosure recommendations. I will be able to do the 1 cu ft sealed, 1.5 cu ft sealed, and the 2 cu ft selaed and ported. I am hoping to understand what sounds best to me in my listening room.
The attached pictures show a completed previous project, rs150 MTM by CJD with the rs28a tweeter for comparison that I use for my HT.
I only have 4 screws in the baffle (will add more) but the test run so far has been very pleasing. I am by no means an audiophile, so I will not try and wax poetic, but I am very excited about this budget design. I must say, the seas tweeter sounds awesome, very similar to the rs28a and even $15 cheaper.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
CJD has a site for his MTM here-
http://www.eldamar.net/audio/rs150mtm/
There is also a write up for BSC and non-bsc designs for a MT. I am going to be adding the non-bsc for on-wall surrounds sometime in the future. That one is here- post #62
http://www.htguide.com/forum/showthread.php4?t=18946&page=2&pp=35
If you look at the write up on his site just swap at the values in the schematic, and it will make sense.
http://www.eldamar.net/audio/rs150mtm/
There is also a write up for BSC and non-bsc designs for a MT. I am going to be adding the non-bsc for on-wall surrounds sometime in the future. That one is here- post #62
http://www.htguide.com/forum/showthread.php4?t=18946&page=2&pp=35
If you look at the write up on his site just swap at the values in the schematic, and it will make sense.
JonPike said:
Well, I wouldn't call it problems with the DA175, just limitations of a lower tech motor design. The two types of distortion we're talking about here are thermal and BL. At lower levels, the DA175 performs on par with the Seas L18. As millimeters of Xmax get used up, the DA175's generic flat and straight pole piece causes BL distortion to accumulate faster than some better motor designs that have better BL curves.
Thermal is simply the driver's ability to maintain it's measurements at higher levels as the voice coil and suspension heat up. This can be easily seen in response and impedance curves that are increased in incremental levels. For example, starting at 90 dB/1m, then running response and impedance plots in increments at levels 5 or 10 dB higher to observe the changes.
This kind of testing is still somewhat important, but I usually don't do it due to time constraints. Soundeasy can do Volterra Series Expansion, which is more of an estimate of a BL curve rather than an actual Klippel-style measurement, but still useful. Some day I'll post a set of measurements so you guys can see what this looks like. I'll use the L18 and DA175 too, as these drivers really point out the difference that motor design can make. People want to just add up the Xmax, calculate out the volume displacement and use that to determine how loud a speaker will get, but it's not that simple. A single L18, through most of it's bandwidth, will play louder with lower distortion than two DA175's. Make no mistake that the DA175 is a great woofer, but the higher price of the L18 does get some performance improvements in this case. This sort of leads into the next question.
keyser said:
The breakup of the DA175 is not really that bad. I chose the lower crossover frequency of the 27TBFCG for other reasons, compared to the 2000Hz in the L18 design. First off, MTM lobing is far worse than MT lobing and the lower crossover point helps minimize this or at least limit it to only woofer c/c issues. If you've ever seen the power response of a large MTM with a high crossover point, you'd know what I'm referring to.
Secondly, the L18 is a system that will play relatively loud. In a system like that, it's wise to cross over the tweeter with consideration to the system's overall abilities. In that system, the tweeter will not be the limiting factor, but if I'd crossed over at 1450Hz, it might be.
Finally, there is an economy to crossover topology. I could have crossed the L18 system over at 1450, but I would not have gotten away with the simple crossover design. The single notch and inductor on the woofer serve multiple response shaping purposes that only worked for the 2000Hz crossover. Crossing over at 1450 would require a much more complex crossover. Likewise, with the DA175, crossing over higher would have required a notch for the breakup and a couple more components to shape the response.
A single DA175 could probably cross over around 2kHz LR4 without distortion issues. On the other hand due to the limited output of the DA175, I don't think I'd want to use only a single one in a system unless it's specifically for low levels only.
I consider all of the above when I pick a crossover point.
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