My friend has asked me to build him a pair of speakers. I have a pair of Alpair 10.2 on the way and I am having difficulty deciding what enclosure to build for them. It is pretty-much down to either Mr. Brines' "M10-A10" enclosure, or Woden "Silbury" enclosure. WAF is not an issue for my friend, but he does not want to supplement bass with a sub. He will be using an NAD 315BEE for the foreseeable future.
I have read Bob's listening notes on the "M10-A10", but I have not been able to find much of the same on the "Silbury".
My friend's goals are maximizing the bass potential of these excellent drivers, but quality, speed and cohesiveness of said bass must not suffer.
Has anyone heard the A10.2 in both of these enclosures?
Bob and Scott, what do you feel are the design highlights of your respective designs?
Does anyone think there is an even better enclosure for the 10.2 ?
Thanks in advance for any/all opinions!
I have read Bob's listening notes on the "M10-A10", but I have not been able to find much of the same on the "Silbury".
My friend's goals are maximizing the bass potential of these excellent drivers, but quality, speed and cohesiveness of said bass must not suffer.
Has anyone heard the A10.2 in both of these enclosures?
Bob and Scott, what do you feel are the design highlights of your respective designs?
Does anyone think there is an even better enclosure for the 10.2 ?
Thanks in advance for any/all opinions!
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See this thread from post 65 onward and understanding will arrive with the subtlety of a bat in the bicuspids 
http://www.diyaudio.com/forums/full-range/227544-what-best-full-range-driver-3.html
I'm afraid I don't discuss the enclosure of mine that you mention on the forum since I'm here purely as a DIYer. However, FWIW:
Without knowing more about your friend's room, system, taste in material & acoustic presentation it's difficult to say anything especially profound. I suspect by 'quality, cohesiveness and speed' we're largely discussing group delay, in which case Bob's MLTL instantly has an advantage since the output from the rear is not expected to go down about 9ft of folded pathway. Since sound travels ~1.13ft / ms, the back-horn in this case has a delay in its functional BW of about 7.96ms. The audiblity depends on the operating BW of the design, the acoustic low-pass slope, and the individual. The lower in frequency you go, the more our hearing acuity drops off, and the less likely you are to hear it, particularly if you've got a steep acoustic low pass. I can say that Silbury is better than many back-horns in this regard, but some people are more sensitive to group delay than others, and either way, Bob's MLTL is inherently superior on this front, and since this is a major consideration, is the obvious choice.
As for any 'better' options; again, this depends on the exact requirements. Neither of the enclosures mentioned are going to be ideal if you're listening in a small box-room in a 1930s British semi-detached house for example in which case you'd likely be better off running it in something like a 10 litre sealed box or similar. Likewise if you're wanting to fill a ballroom, something the size of a Kleinhorn may be in order.
http://www.diyaudio.com/forums/full-range/227544-what-best-full-range-driver-3.htmlI'm afraid I don't discuss the enclosure of mine that you mention on the forum since I'm here purely as a DIYer. However, FWIW:
Without knowing more about your friend's room, system, taste in material & acoustic presentation it's difficult to say anything especially profound. I suspect by 'quality, cohesiveness and speed' we're largely discussing group delay, in which case Bob's MLTL instantly has an advantage since the output from the rear is not expected to go down about 9ft of folded pathway. Since sound travels ~1.13ft / ms, the back-horn in this case has a delay in its functional BW of about 7.96ms. The audiblity depends on the operating BW of the design, the acoustic low-pass slope, and the individual. The lower in frequency you go, the more our hearing acuity drops off, and the less likely you are to hear it, particularly if you've got a steep acoustic low pass. I can say that Silbury is better than many back-horns in this regard, but some people are more sensitive to group delay than others, and either way, Bob's MLTL is inherently superior on this front, and since this is a major consideration, is the obvious choice.
As for any 'better' options; again, this depends on the exact requirements. Neither of the enclosures mentioned are going to be ideal if you're listening in a small box-room in a 1930s British semi-detached house for example in which case you'd likely be better off running it in something like a 10 litre sealed box or similar. Likewise if you're wanting to fill a ballroom, something the size of a Kleinhorn may be in order.
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In my last place I had a very small room with a 1/3 octave wide suck out centered around 45hz. In my new place in a massive room I have a beautiful peak about a 1/2 octave wide nice and low q peak centered around 52hz and have no suck outs until output drops off below 13hz. Not sure the size of room is a good indicator. Really need to measure the speakers anechoic response and then response at the LP to know how the room responds to the speaker.
See this thread from post 65 onward and understanding will arrive with the subtlety of a bat in the bicuspids
I'm afraid I don't discuss the enclosure of mine that you mention on the forum since I'm here purely as a DIYer. However, FWIW:
Without knowing more about your friend's room, system, taste in material & acoustic presentation it's difficult to say anything especially profound. I suspect by 'quality, cohesiveness and speed' we're largely discussing group delay, in which case Bob's MLTL instantly has an advantage since the output from the rear is not expected to go down about 9ft of folded pathway. Since sound travels ~1.13ft / ms, the back-horn in this case has a delay in its functional BW of about 7.96ms. The audiblity depends on the operating BW of the design, the acoustic low-pass slope, and the individual. The lower in frequency you go, the more our hearing acuity drops off, and the less likely you are to hear it, particularly if you've got a steep acoustic low pass. I can say that Silbury is better than many back-horns in this regard, but some people are more sensitive to group delay than others, and either way, Bob's MLTL is inherently superior on this front, and since this is a major consideration, is the obvious choice.
As for any 'better' options; again, this depends on the exact requirements. Neither of the enclosures mentioned are going to be ideal if you're listening in a small box-room in a 1930s British semi-detached house for example in which case you'd likely be better off running it in something like a 10 litre sealed box or similar. Likewise if you're wanting to fill a ballroom, something the size of a Kleinhorn may be in order.
Yes, I am following that thread. Bob's comment there about knowing the players and then deciding for oneself how much salt to consume along with the advice is bang on.
However, I think it is quite fair for both you and Bob to openly discuss these two (non-free) designs and what you feel are the pros and/or cons of each. I have directly asked you both, and it is no secret that one of you will be paid for whichever design is ultimately chosen. It is a level playing field.
While it might seem to break some sort of rules to discuss designs which you and Bob respectively profit from, it is certainly to my advantage as the potential customer to hear them discussed in an open forum (this is not to infer that I think either one of you would be less than honest in a one-on-one conversation).
Anyway, I appreciate your objective approach to the subject thus far.
My buddy's room is about 15'x20', and he has the flexibility of moving things around if necessary, so his placement options are numerous. He did say he'd rather have the speakers within 6" or so of the back wall, as he doesn't like the idea of "wasting" a meter of his room just for better "imaging or whatever".
I'll have to talk to him more about his wants/needs, but in the meantime, is it right to assume that if the A10-M10 wins at bass timing, the Silbury wins at "sheer amount of bass", or do they both pretty much hit F3~40Hz and F10~30Hz? I look at that big Silbury cabinet and my gut tells me it goes lower than the MLTL... Is my gut wrong?
Scott, have you got simulated or measured FR curves of the 10.2 Silbury?
I'll have to talk to him more about his wants/needs, but in the meantime, is it right to assume that if the A10-M10 wins at bass timing, the Silbury wins at "sheer amount of bass", or do they both pretty much hit F3~40Hz and F10~30Hz? I look at that big Silbury cabinet and my gut tells me it goes lower than the MLTL... Is my gut wrong?
Scott, have you got simulated or measured FR curves of the 10.2 Silbury?
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We have M10-A10 here. No Silbury thou. We have had Bernie's Victor here (broadly similar to Silbury with FE166). That produces more bass with greater ease than M10-A10. Given greater bass capability of A10.2 over FE166 my guess would be that Silbury would have more kick... only a guess based on an extrapolation.
dave
dave
Says it all about room acoustics.
I concur with Bob's remarks. Re the latter, I take your point, but there are two further considerations at play. Firstly, I have a basic stance, and I try to stick to it, without exception. Secondly, the site in question is not linked to by me, nor is it advertised. As far as I'm concerned, it sits quietly where it is, minding its own business. If people run across it, like what they see, and wish to buy something, that's very nice. If they don't, I'm honestly not fussed. It pays for the occasional tank of fuel for the car, perhaps a new CD / DVD or similar. That's it. I make no attempt to sell anything there at all.
Indeed I have. My usual response though is 'what would you like them to look like?' This is the issue with in-room response curves; within certain broad trends, it's possible to make them look pretty much however you want them to look by changing the measurement / simulation conditions. FWIW though, here's an example. Box angled 45 degrees into the room; 1m distance, on-axis, carpeted floor, 8ft ceiling, edges of the front baffle 2ft from the front & side walls. As you can see, it's a high-gain design to allow greater placement fexibility since you can get rid of what you don't require. Once damped to ~flat, F10 will be similar to Bob's MLTL, but the overall sound will be very different on the bottom end given the respective radiating areas etc.
FWIW, I still suspect your friend will be better off with Bob's MLTL.
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Clear as mud
But at least you leave no doubt about the fact that you are not trying to sell your design Now all we need is for Bob to log in and say that he thinks the Silbury is better for my friends' needs.
Honestly, I am tempted to go with the Silburys simply because it sounds like Scott owns the only pair. My friend might not even be able to tell the difference between the two...
Scott, with a horn, can you nearfield mic the driver and the horn mouth and combine them like a ported speaker, or how do you do that? I've got no experience with horns. I worked on a horn with the alpair10BW but wasn't sure what to do with that. I wasn't so concerned with bass anyways, just the >300hz frequency response which wasn't affected by my farfield measurement.
Edit - I did measure impedance which was crazy in the bass region. This wasn't a surprise really though, I expected that. I wasn't sure how to determine tuning from it though. 2 or 3 troughs in the impedance iirc.
Edit - I did measure impedance which was crazy in the bass region. This wasn't a surprise really though, I expected that. I wasn't sure how to determine tuning from it though. 2 or 3 troughs in the impedance iirc.
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You can, assuming quasi-anechoic is required. If you've got a design that employs boundary loading, i.e. the room boundaries actualy form a part of the horn expansion, it gets a bit more complicated, since removing that means the final part of the horn has gone AWOL, which throws the results.
The impedance measurements you mention you took sounds about par for the course, since the cabinet presumably wasn't impedance matched down to the 1/4 wave cutoff frequency (F0). Ergo, below Fc (the frequency to which it's impedance matched) you've got pipe harmonic resonances. Here you go; a series of impedance values arranged in two columns, top to bottom. This is a pipe of fixed axial length, throat area, and driver location, expanding in a linear fashion (i.e. a conical horn). The driver is generic, the actual dimensions of the pipe were fairly arbitary, although I set length to approximately 1/2 wave at 100Hz. Top left has the smallest terminus area. Bottom right the largest. You can see the harmonics gradually vanish as terminus area increases until its finally getting near to being impedance matched at F0, leaving just the single large peak at tuning.
I don't have a pair myself; I don't have the space. There are a couple out in the wild though.
He would. Back horns don't often sound like a regular box speaker; if he hasn't heard any & is considering these, I'd strongly advise he listens to a pair with a similar terminus configuration if possible (FH3 or something like that) & thinks long & hard before making a decision.
The impedance measurements you mention you took sounds about par for the course, since the cabinet presumably wasn't impedance matched down to the 1/4 wave cutoff frequency (F0). Ergo, below Fc (the frequency to which it's impedance matched) you've got pipe harmonic resonances. Here you go; a series of impedance values arranged in two columns, top to bottom. This is a pipe of fixed axial length, throat area, and driver location, expanding in a linear fashion (i.e. a conical horn). The driver is generic, the actual dimensions of the pipe were fairly arbitary, although I set length to approximately 1/2 wave at 100Hz. Top left has the smallest terminus area. Bottom right the largest. You can see the harmonics gradually vanish as terminus area increases until its finally getting near to being impedance matched at F0, leaving just the single large peak at tuning.
I don't have a pair myself; I don't have the space. There are a couple out in the wild though.
He would. Back horns don't often sound like a regular box speaker; if he hasn't heard any & is considering these, I'd strongly advise he listens to a pair with a similar terminus configuration if possible (FH3 or something like that) & thinks long & hard before making a decision.
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May I say the following:
I don't do back-horns because they are too big to ship by FedEx and WAF will not permit very tall speakers.I don't do corner-horns because my home doesn't have any suitable symmetrical corners. A MLTL for the A10.2 is a no-brainer. The A10.2 works very well in a remarkably small BR, but that's another story.
When I was doing the the design for the M10-A10, I needed something to break in the the drivers, so I built a pair of Pensil's. Six boards and some polyfil. Done! They sound pretty darn good too. I have a problem, though, with stuffing out unwanted harmonics. So I went about designing out the majority of the bad harmonics, and rather that stuff the cabinet, I line the cabinet with 1" fiberglass. The result is a cabinet with much less volume and somewhat better bass response. I am told that the M10-A10 can be a bit boomy, and if yours is, a bit of port damping will fix it.
I am quite happy with the M10-A10. It is one of my better designs, up there with my FT-1600 and the TT-2000. But then, the choice is yours.
Bob
I don't do back-horns because they are too big to ship by FedEx and WAF will not permit very tall speakers.I don't do corner-horns because my home doesn't have any suitable symmetrical corners. A MLTL for the A10.2 is a no-brainer. The A10.2 works very well in a remarkably small BR, but that's another story.
When I was doing the the design for the M10-A10, I needed something to break in the the drivers, so I built a pair of Pensil's. Six boards and some polyfil. Done! They sound pretty darn good too. I have a problem, though, with stuffing out unwanted harmonics. So I went about designing out the majority of the bad harmonics, and rather that stuff the cabinet, I line the cabinet with 1" fiberglass. The result is a cabinet with much less volume and somewhat better bass response. I am told that the M10-A10 can be a bit boomy, and if yours is, a bit of port damping will fix it.
I am quite happy with the M10-A10. It is one of my better designs, up there with my FT-1600 and the TT-2000. But then, the choice is yours.
Bob
I have a thread that talks to my MLTL design for the Alpair 10.1 and later for compatibility with the 10.2. You might read that thread:
http://www.diyaudio.com/forums/full-range/137585-mark-audio-alpair-10-mltl-design.html
I also did an open back 10.2 version in 2011 with an active DSP crossover from an Eminence 3015LF Neo Kappalite 15" woofer. The latter is one of my best speakers from a sound viewpoint but it is too much machinery and spacing into the room for your friend's needs.
My MLTL performs similar to Bob Brines but his design has more maturity and data points at this time. If the cost of Bob's plans choke the horse, get back with me and I'll help work the details of my design with you. Otherwise, I have confidence that Bob's design will fill your needs.
http://www.diyaudio.com/forums/full-range/137585-mark-audio-alpair-10-mltl-design.html
I also did an open back 10.2 version in 2011 with an active DSP crossover from an Eminence 3015LF Neo Kappalite 15" woofer. The latter is one of my best speakers from a sound viewpoint but it is too much machinery and spacing into the room for your friend's needs.
My MLTL performs similar to Bob Brines but his design has more maturity and data points at this time. If the cost of Bob's plans choke the horse, get back with me and I'll help work the details of my design with you. Otherwise, I have confidence that Bob's design will fill your needs.
Scottmoose,
This is the open baffle thread:
http://www.diyaudio.com/forums/full...rk-audio-alpair-10-2-open-baffle-project.html
Jim
This is the open baffle thread:
http://www.diyaudio.com/forums/full...rk-audio-alpair-10-2-open-baffle-project.html
Jim
Oh, they're doing fine. I finished the prototypes and they are the current speakers in my 2-ch. I have offered they for beta testing through my personal forum. The boxes I will use for demo's are in cherry with a high gloss finish. Pictures attached. The bass that comes out of those little boxes is crazy. F10 just below 40Hz, and at an 80dB listening level, there is room for some bass boost. For those going to Dallas for LSAF, I will have these there.
A note on the high gloss finish: I did it just to prove to myself that I could do it. But it anyone wants to buy a set, add $200 just for the finish. It is a mother bear.
Bob
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Jim,
Thanks for the link to your MLTL thread. I like the design, but I'll have to see if my friend feels the same way.
Yes, I had seen that OB + H frame system thread before. Very cool setup. I can just imagine the sound. Low WAF, lots of space usage, extra gear... as you say.
The cost of plans is quite small, all things considered, so this is really about what design my friend will like the best. I do appreciate you putting your design out there for us DIYers and I think if it was me I might chose your design. I like the fact that they are tall.
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