I hate to keep repeating myself over and over, but I guess that I have to. When I say "random" I don't mean completely random in this context. The term here comes from my discussion with Todd Welti who claimed that four woofers placed mid-way along all four walls was "the best" response obtainable. I disputed this because I showed that one sub in a corner, one along the far midwall and the other as far away from the first two as possible but above the midline and NOT in a corner would work as well with three subs as his did with four subs. Because there is so much flexibility in this approach I tend to call it "random". But there are some rules that make things work better.
I have found that random placement, but keeping the subs as far apart as possible, does work OK. Its also almost essential to put one sub in a corner, but otherwise the choice of location is rather arbitrary. So NO, its not truely random, but compared to fixed locations along the walls this IS pretty random.
I have found that random placement, but keeping the subs as far apart as possible, does work OK. Its also almost essential to put one sub in a corner, but otherwise the choice of location is rather arbitrary. So NO, its not truely random, but compared to fixed locations along the walls this IS pretty random.
I don't see how this is so difficult for everyone to understand. The one sub setup states to use four modules and place each at the midpoint of each wall. The other states to use three modules placing one in a corner, the other two around the room with one of those being placed above the mid point height wise of the room.
I can't say that I study these things at all but Geddes recommendation makes more sense to me as I have never heard about placing a sub above a centerline before. Knowing that the acoustical space is a 3 dimensional makes me think that placing a sub off of the ground should help with an even response.
A 'random' placement of three subs seems to be a lot more feasible solution than four at dedicated locations. The four subs would have to be placed in the middle of the room where possible walkways might be. Geddes solution possibly places two of the three on the front wall with the third sub being somewhere else around the room that fits the environment.
Either way, let's stop splitting hairs over the use of 'random' and the like.
I can't say that I study these things at all but Geddes recommendation makes more sense to me as I have never heard about placing a sub above a centerline before. Knowing that the acoustical space is a 3 dimensional makes me think that placing a sub off of the ground should help with an even response.
A 'random' placement of three subs seems to be a lot more feasible solution than four at dedicated locations. The four subs would have to be placed in the middle of the room where possible walkways might be. Geddes solution possibly places two of the three on the front wall with the third sub being somewhere else around the room that fits the environment.
Either way, let's stop splitting hairs over the use of 'random' and the like.
This explanation sounds like putting one sub on a node, the other two subs on anti-nodes of opposite sign,
Soongsc
There was an entire thread some time back - with math and all - mostly between John K and I about modeling the LF sound field in a room. The math can also be found in Todd Welti's paper and my comments on what he did are in a follow up letter to the AES. I am not inclined to go through it all again here if you are unwilling to look up what has already been written and discussed and read it there. And anyways this is not the forum for math, its simply not possible, nor advisable.
"This explanation sounds like putting one sub on a node, the other two subs on anti-nodes of opposite sign," Well its just not that simple. There are many modes and many nodes and anti-nodes to consider not just one or two. You'll get a lot further if you think of the problem statistically - what is the "most likely" way to achieve a smooth "spatial and frequency variance" in an "typical" room at LFs. There is simply no way to approach the problem in any other sense. Sure if you have a particular room and a particular setup then you can measure this exact situation (as I have told Markus in other threads) and improve things further, but it only makes sense to start out with the "most likely" situation to get to the best end results. No two rooms are the same and there is no fixed set of rules that will work.
There was an entire thread some time back - with math and all - mostly between John K and I about modeling the LF sound field in a room. The math can also be found in Todd Welti's paper and my comments on what he did are in a follow up letter to the AES. I am not inclined to go through it all again here if you are unwilling to look up what has already been written and discussed and read it there. And anyways this is not the forum for math, its simply not possible, nor advisable.
"This explanation sounds like putting one sub on a node, the other two subs on anti-nodes of opposite sign," Well its just not that simple. There are many modes and many nodes and anti-nodes to consider not just one or two. You'll get a lot further if you think of the problem statistically - what is the "most likely" way to achieve a smooth "spatial and frequency variance" in an "typical" room at LFs. There is simply no way to approach the problem in any other sense. Sure if you have a particular room and a particular setup then you can measure this exact situation (as I have told Markus in other threads) and improve things further, but it only makes sense to start out with the "most likely" situation to get to the best end results. No two rooms are the same and there is no fixed set of rules that will work.
I have done the analysis - about 30 years worth, starting with my PhD thesis back in 1981 - and I gave you the references. Here, I am just posting the results. They are not "guesses" they are the results of numerous studies and years of implimentations. If you want the details behind it you have to do the work to find it and read it.
I guess that there are lots or updates.
Weather conditions have forced me to move my entire "plant" from the garage to the basement. This will have a positive long term effect because of better temp and humidity control, but necessitated a large delay while I moved everything.
John has been pretty late with delivery of a trial set of Abbey enclosure parts, but he promises them next week.
I've had to completely redo all of the tooling for the waveguides owing to some problems with the edges on them curly up. I also had serious problems with the poly sticking to the steel back molds. So I have completely redone the molds for the 10" in a different material and now get a much better, more consistant cast. I will redo the Abbey tools when I get the parts from John.
For those who want to try and cast or make their own waveguides, all I can say is that I am now on my fourth set of molds. Nothing is as easy or ever goes as well as we presume it is or will be.
I am shipping full Nathan kits now with only about a week or two back log.
I also invested in a high performance spray outfit to get a better paint finish on the kits that I make. I can now get a very fine finish and it gets better all the time. As anyone who has done really high quality paint will tell you, it takes a lot of practice to get right.
I am sending out the first set of audition/demo speakers next week.
Bottom line here is that progress is slow but sure. Every step is an improvement in quality. I'll be making waveguides in 10" and 12" in poly in a very short while. The poly waveguides are highly attractive to me because they are very strong and well damped - unlike fiberglass or metal. Its really a great material for that application. It could even be molded in colors although I haven't tried that yet. They are white as that the natural material color.
Weather conditions have forced me to move my entire "plant" from the garage to the basement. This will have a positive long term effect because of better temp and humidity control, but necessitated a large delay while I moved everything.
John has been pretty late with delivery of a trial set of Abbey enclosure parts, but he promises them next week.
I've had to completely redo all of the tooling for the waveguides owing to some problems with the edges on them curly up. I also had serious problems with the poly sticking to the steel back molds. So I have completely redone the molds for the 10" in a different material and now get a much better, more consistant cast. I will redo the Abbey tools when I get the parts from John.
For those who want to try and cast or make their own waveguides, all I can say is that I am now on my fourth set of molds. Nothing is as easy or ever goes as well as we presume it is or will be.
I am shipping full Nathan kits now with only about a week or two back log.
I also invested in a high performance spray outfit to get a better paint finish on the kits that I make. I can now get a very fine finish and it gets better all the time. As anyone who has done really high quality paint will tell you, it takes a lot of practice to get right.
I am sending out the first set of audition/demo speakers next week.
Bottom line here is that progress is slow but sure. Every step is an improvement in quality. I'll be making waveguides in 10" and 12" in poly in a very short while. The poly waveguides are highly attractive to me because they are very strong and well damped - unlike fiberglass or metal. Its really a great material for that application. It could even be molded in colors although I haven't tried that yet. They are white as that the natural material color.
oh I had it in my head that you already were doing the guides in poly, or at least something other than fiberglass.
Ok well good to know its moving along and that there will be quality improvements along the way. I know its hard for you to judge, especially with delays, but if you were to give a guess range on the Abbeys for us in the first batch, what would you say. 2 months, 3 months, 6 months?
Ok well good to know its moving along and that there will be quality improvements along the way. I know its hard for you to judge, especially with delays, but if you were to give a guess range on the Abbeys for us in the first batch, what would you say. 2 months, 3 months, 6 months?
I'm talking about the stand alone waveguides in Poly. What I had been selling were fiberglass.
I am only waiting on John for the Abbey parts at this point and he says this week. I could be shipping by next week. Everything else is done. I will probably wait and build up a set to test and listen to, but that almost never results in any changes. (Although the Nathan crossover changed a little bit after the first test of production parts.)
I am only waiting on John for the Abbey parts at this point and he says this week. I could be shipping by next week. Everything else is done. I will probably wait and build up a set to test and listen to, but that almost never results in any changes. (Although the Nathan crossover changed a little bit after the first test of production parts.)
I'm not sure what you are doing with this, but if there is any assembly with the crossovers, I can do that myself. In fact, while I will take the parts since I'm paying for them, I have a box-o-parts full of crossover parts, so if small changes are made, I probably have whats needed to make the chance. For instance, if you were to increase or decrease the value of a part slightly, I'm sure I could manage that. I can measure inductance, so reducing inductance is no issue, I have lots of small and some larger value caps, so again, not a big deal.
While its way more expensive that I realized, I did buy a used coil winder on ebay, and so when it arrives, I will have the ability to wind my own coils too. I've been stalking up on old steel laminate inductors, with the hope that I can reuse the bobbins to make my own. I also bought some very large toroid cores to use in some toroid core inductors. Air core can be wound on a cardboard sleeve or even nothing at all. The biggest challenge there is the wire. It takes 100's of feet of wire just to make one, which means I really need to buy 1-2000 feet of wire in any one size just to make a few inductors. I also should pick up some hard board and craft paper tubes or cardboard tubes to wind on to set the diameter and width.
Let me know when to send the rest of the money then. I'm excited that they may come soon. I also just bought a bigger air tool setup and now have a few air sanders (Man they sound horrible), some new paint guns, a new half inch router, a 1.5" round over bit, a new drill press, and a few other assorted things.
While its way more expensive that I realized, I did buy a used coil winder on ebay, and so when it arrives, I will have the ability to wind my own coils too. I've been stalking up on old steel laminate inductors, with the hope that I can reuse the bobbins to make my own. I also bought some very large toroid cores to use in some toroid core inductors. Air core can be wound on a cardboard sleeve or even nothing at all. The biggest challenge there is the wire. It takes 100's of feet of wire just to make one, which means I really need to buy 1-2000 feet of wire in any one size just to make a few inductors. I also should pick up some hard board and craft paper tubes or cardboard tubes to wind on to set the diameter and width.
Let me know when to send the rest of the money then. I'm excited that they may come soon. I also just bought a bigger air tool setup and now have a few air sanders (Man they sound horrible), some new paint guns, a new half inch router, a 1.5" round over bit, a new drill press, and a few other assorted things.
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