Hey, you're the one still going on about it. I only came here questioning it at first, because with a forum signature like yours, I began to wonder how anyone's experiments justified spending $3k on four woofers to be used below 80 Hz, that's all.
But you don't know what to do with those $720/each drivers you supposedly purchased. How's that an informed buying decision??
I'm not attempting to attack you, never was. I've made plenty of similar mistakes myself in the past.. even the EXACT same mistake of spending thousands on four 15" woofers! In the last several years, I've also lost hundreds of thousands of dollars all together, as a result of the mistakes I made a long time ago during a very tough time in my life. And I certainly have no problem admitting that. On the bright side, I've learned from it, and I'll never make any of those mistakes again.
Apology accepted.
Sorry for your wallet.
Cya.
thadman said:
But you don't know what to do with those $720/each drivers you supposedly purchased. How's that an informed buying decision??
I'm not attempting to attack you, never was. I've made plenty of similar mistakes myself in the past.. even the EXACT same mistake of spending thousands on four 15" woofers! In the last several years, I've also lost hundreds of thousands of dollars all together, as a result of the mistakes I made a long time ago during a very tough time in my life. And I certainly have no problem admitting that. On the bright side, I've learned from it, and I'll never make any of those mistakes again.
thadman said:
Apology accepted.
Sorry for your wallet.
Cya.
I did not pay MSRP on the woofers, the reason I purchased them was because I got a great deal on them a long time ago that I couldn't pass up. My wallet feels fine
Another thing to consider, is Live.com still doing that 30% off ebay purchase program? I've seen several NEW Crown XLS5000Ds listed at $1200 buy it now plus a $300 mail in rebate. $2400($1200 x 2) times .7 = $1680 - $600 in rebates = $1080 for 10,000 watts of amplification at 4ohms or 4x 1800 watts @ 4ohms. 10,000 watts...
XTi4000s have been listed around $750 but with no mail-in-rebate. I'd pay around $1050 for two NEW XTi4000s (1200w/channel @ 4ohms vs 1800w/channel @ 4ohms) which include a lot of DSP features.
Another thing to consider, is Live.com still doing that 30% off ebay purchase program? I've seen several NEW Crown XLS5000Ds listed at $1200 buy it now plus a $300 mail in rebate. $2400($1200 x 2) times .7 = $1680 - $600 in rebates = $1080 for 10,000 watts of amplification at 4ohms or 4x 1800 watts @ 4ohms. 10,000 watts...
XTi4000s have been listed around $750 but with no mail-in-rebate. I'd pay around $1050 for two NEW XTi4000s (1200w/channel @ 4ohms vs 1800w/channel @ 4ohms) which include a lot of DSP features.
Hey, ease guys, those are exstremely fine drivers that will do an impressive speaker setup
But I am uncertain about your goal, I mean exstreme SPL with a 6" and ribbon
You are concerned that the midbass will run out of steam
Are you sure its not the mid and tweeter you should be concerned about
But I am uncertain about your goal, I mean exstreme SPL with a 6" and ribbon
You are concerned that the midbass will run out of steam
Are you sure its not the mid and tweeter you should be concerned about
tinitus said:
The RAAL should easily manage 110dB continuous with the correct amplification as per Shinobiwan, although I would have liked to use the higher end PRO version I currently cannot afford it.
The midrange is questionable, the current candidate is the AE TD6.5M with Apollo and Alnico motor upgrades, but am awaiting on objective measurements regarding their performance before purchasing. Another option would be the TD6.5P at 97+dB, but that would require a slightly higher crossover point.
Wait just a little longer for the upcoming waveguide, do a 2-way with the TD15M (it does mids really well for a 15, as you probably already know), along with a nice compression driver with an aluminum or polyester diaphragm.. give it a continuous 120+ dB all day long, problem solved. Plus, if you were planning to go active with all this, you'd actually save money this way versus doing a 3-way. 3-ways are usually a bigger pain in the *** anyway IMO. Also, less crossovers, which is almost always a good thing.
thadman said:
As far as I know exstreme SPL can ruin the alnico making it loose its power, but cant say fore sure
About the 80hz rolloff of the TD15M
As it has a natural rolloff around 70hz, or just below, I would expect it to be rather difficult to make it rolloff at 80hz, but I havent tried it so cant say, just a suspicion
thadman said:
That should be more than sufficient. I prefer the Velodyne SMS-1 despite its cost and lower flexibility, simply because the integrated measurement system is so easy and quick to use.
thadman said:
In this forum, look for the threads in the main speaker section about setting up the Nathan10, or maybe the Vendor's Bazaar section on the DIY Waveguide kit for information by Dr. Geddes and others. I will say that since I started using his ideas to set up and integrate my subwoofer systems a couple years ago, I cannot imagine going to a different paradigm. This one just works so well.
Another interesting option (if you wanted to complicate things a little) would be to add passive radiators to form a high quality resonant system. Put each 15 in a 6 cube box loaded with a pair of Creative Sound's PR1821s with about 300 grams of mass added to each one(resulting in about a 16 hz tune). The result will be a nuclear low end capable of of over 123db from 16 hz up anechoic! Depending on your room , you'll probably get a minimum 6 db addtional gain. The downside is this system has to have a subsonic filter & you would have to spring for an additional 8pr's at a mere $139 each. Aren't decisions like this fun?
Aren't decisions like this fun?Pallas said:
BHTX said:
Sorry to thread hijack, I have talked with John about this a few times. Its not in the planning stages but a few things have been drawn on the paper napkins. This is not an easy one to do and will take some time/money to figure out.
Now back to the program of a seriously potent speaker system...........
I'm familiar with the theory behind the Geddes model, use as many sources as possible to more evenly disperse the LF energy in a way that positively excites the modal resonances within the room. But not the details of the model, where to place the subwoofers (Harmon Kardon recommends placing one at the center of each wall)...the desired rolloff...the desired level of each driver...etc I've done research and haven't been able to find the answers to these questions. The thinking assumed for mid to high frequency drivers (placing drivers within 1/4WL to avoid power response aberrations related to phase, although not always achievable this would be optimal) does not necessarily apply to LF drivers as waves behave very differently in the modal region than they do higher in the spectrum where sound behaves closer to the ray model. Could anybody offer any insight into this?
Some thoughts. placing subwoofers near the positions of the nodes of the axial modes (no excitement for that particular mode) would be easy to predict, but the tangential modes would be much more difficult and would require a very dense grid of subwoofers. The larger subwoofers designed for the lowest frequency would intuitively be placed at the positions of the lowest nodes and would gradually rolloff higher in frequency. The lower displacement drivers (ie visually less obtrusive) would be located at higher frequency nodes and would gradually rolloff below the point where the node functions.
While I'm quite familiar with the Harmon papers, I'm less so with Dr. Geddes approach. Please correct me if I have mistaken impressions.
The approaches differ in their goals.
For the harmon approach Harmon, the intent is to minimize the excitement of room modes using two techniques: locating subwoofers at nulls in the modes, and locating pairs of subwoofers such that the excite the same mode 180 degrees out of phase, canceling that mode. It's also assumed that a single equalization will be applied to all subs (this is important: Harmon is optimizing for uniformity, not necessarily flat response).
For Dr. Geddes I believe the idea is to to use a single corner placed sub to maximally excite all modes. Then additional subs are placed at random location in the room. These will re-enforce some models while canceling others. These can be used to "fill in" some of the gaps created by the strong modal excitement of the corner place subwoofer. The level of each subwoofer is adjusted to provide the flattest total response. I can't recall if Dr. Geddes assumes equalization is used.
The results in the Harmon papers are impressive, and the carefully designed placement clearly gives better results than merely hoping that multiple subwoofers will have a smooth response. On the other hand it seems impossible to apply their approach without measuring equipment and equalization. It also is less useful for strangely shaped rooms where it may not be easy to determine where nulls and cancellation pairs are located.
From what I recall of the Harmon papers, the axial modes dominate the situation, which is nice since avoiding or canceling tangental or oblique modes could be very complicated.
Dr. Geddes approach seems more practical for most home situations. It should provide more efficiency overall, since it works with the rooms modes rather than attempting to avoid them. It also is easier to adapt to unusual rooms, since corners in such rooms are still likely to excite a lot of modes. Also since the placement of the other subwoofers can be more arbitrary, it's better able to handle practical constraints of where you want your furniture, etc.
Dr. Geddes also has some data on his website, I assume from simulations. From what I recall there are two interesting details there: one is that placement of a monopole source in the middle of a wall up above the floor shows a quite even response. Also, a cardioid source placed in the corner shows the lowest variation, but not dramatically so.
Personally I'm interested in both approaches and am considering designs along both lines. I also think a vertical tapped horn with it's aperture above the floor might be an interesting approach. I suspect in my current living situation however that cardioids would be the best solution: my upstairs neighbors are very understanding but would likely welcome even a slight reduction in how much bass I couple into the frame of the house
I'd really like to duplicate the simulation results from both approaches as well as try some other ideas, but I keep procrastinating on learning enough mathematica to do so.
The approaches differ in their goals.
For the harmon approach Harmon, the intent is to minimize the excitement of room modes using two techniques: locating subwoofers at nulls in the modes, and locating pairs of subwoofers such that the excite the same mode 180 degrees out of phase, canceling that mode. It's also assumed that a single equalization will be applied to all subs (this is important: Harmon is optimizing for uniformity, not necessarily flat response).
For Dr. Geddes I believe the idea is to to use a single corner placed sub to maximally excite all modes. Then additional subs are placed at random location in the room. These will re-enforce some models while canceling others. These can be used to "fill in" some of the gaps created by the strong modal excitement of the corner place subwoofer. The level of each subwoofer is adjusted to provide the flattest total response. I can't recall if Dr. Geddes assumes equalization is used.
The results in the Harmon papers are impressive, and the carefully designed placement clearly gives better results than merely hoping that multiple subwoofers will have a smooth response. On the other hand it seems impossible to apply their approach without measuring equipment and equalization. It also is less useful for strangely shaped rooms where it may not be easy to determine where nulls and cancellation pairs are located.
From what I recall of the Harmon papers, the axial modes dominate the situation, which is nice since avoiding or canceling tangental or oblique modes could be very complicated.
Dr. Geddes approach seems more practical for most home situations. It should provide more efficiency overall, since it works with the rooms modes rather than attempting to avoid them. It also is easier to adapt to unusual rooms, since corners in such rooms are still likely to excite a lot of modes. Also since the placement of the other subwoofers can be more arbitrary, it's better able to handle practical constraints of where you want your furniture, etc.
Dr. Geddes also has some data on his website, I assume from simulations. From what I recall there are two interesting details there: one is that placement of a monopole source in the middle of a wall up above the floor shows a quite even response. Also, a cardioid source placed in the corner shows the lowest variation, but not dramatically so.
Personally I'm interested in both approaches and am considering designs along both lines. I also think a vertical tapped horn with it's aperture above the floor might be an interesting approach. I suspect in my current living situation however that cardioids would be the best solution: my upstairs neighbors are very understanding but would likely welcome even a slight reduction in how much bass I couple into the frame of the house
I'd really like to duplicate the simulation results from both approaches as well as try some other ideas, but I keep procrastinating on learning enough mathematica to do so.
The best one could do is to try alot of different sub placement configurations oneself. Room modes are so complex that rules of thump only get you so far. I ended up with 4 subs, each one in the middle of one wall, but 2 subs on opposing wall midpoints is not really worse. To be honest, i couldnt get gedlees approach to work nearly as good as the harman approach and the symmetrie in the later one makes it alot more pleasing for my eyes.
Thadman project
Thadman:
Sounds like an interesting project. I don't want to hijack your thread, and cannot really help you with your sub issue, but would like to ask you your opinion on the TD15M. Have you listened to this yet? It looks like a great driver. I'm looking at the TD series for my project also, for the range of 40 to 200. I want to avoid subs if possible.
I do want to put forth one idea for you to consider...have you considered compression drivers rather than the AE 6.5? I think that 6.5 is going to be a great driver, but do you think the limited cone area will keep up with the rest of your system? I have a TAD 12" for midbass, which is roughly comparable to your TD, crossing to a JBL 2344a at 1200 with a TDM active crossover. I chose the JBL for it's great sound, efficiency, dynamics, and 100 x 100 dispersion. In my admittedly limited experience with horns, it is the only one that to me does not sound like a "horn". It would do a beautiful job of the stated goals of your system, but would be best done actively, which is pretty cheap and easy these days.
I apologize in advance if my suggestion about the AE 6.5 is unwanted...but it is not available quite yet anyway.
Have fun!
Thadman:
Sounds like an interesting project. I don't want to hijack your thread, and cannot really help you with your sub issue, but would like to ask you your opinion on the TD15M. Have you listened to this yet? It looks like a great driver. I'm looking at the TD series for my project also, for the range of 40 to 200. I want to avoid subs if possible.
I do want to put forth one idea for you to consider...have you considered compression drivers rather than the AE 6.5? I think that 6.5 is going to be a great driver, but do you think the limited cone area will keep up with the rest of your system? I have a TAD 12" for midbass, which is roughly comparable to your TD, crossing to a JBL 2344a at 1200 with a TDM active crossover. I chose the JBL for it's great sound, efficiency, dynamics, and 100 x 100 dispersion. In my admittedly limited experience with horns, it is the only one that to me does not sound like a "horn". It would do a beautiful job of the stated goals of your system, but would be best done actively, which is pretty cheap and easy these days.
I apologize in advance if my suggestion about the AE 6.5 is unwanted...but it is not available quite yet anyway.
Have fun!
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