Thanks for the input and charts guys.
Auplater, very nice work! Would love to see what the rest of the setup looks like.
Bjorno, thanks for those simulations. Unfortunately, I'm not 100% certain of what I'm looking at, but I think I get the idea.
Anyway, I think I might have figured out a solution to this project...
First off, I'm going to scrap the entire idea of building the LA's with the Dayton Classic drivers. Not only are they too large, but they also have those midrange issues and will not match up to the Dayton planars properly.
So what I think I will do now is this...
I will buy a total of (20) GR M-130 drivers and a total of (15) Dayton PT2C-8 planars. The left and right channels will each have EIGHT woofers and SIX planars, the center channel will be exactly half with FOUR woofers and THREE planars.
This will keep me in budget (just over $1k for drivers alone), will provide better performance due to the better quality woofers, they are smaller and their C-T-C will be closer allowing for a higher xover freq to match up with the planars (2kHz), will be a nominal 4 ohms for the main channels (nominal 8 ohms for the center channel), the main channels will probably extend down into the mid-30's pretty well, and will be like the smaller, cheaper baby brother of the GR LS-6. :thumb:
From the looks of the plot on GR's website for the M-130, even off axis, a 2kHz xover point looks to be well within reach as the driver seems to be flat at 2kHz. Since if I am staying with the Dayton planars due to their price and performance, I am stuck with a minimum xover point of 2kHz and from what I gather, C-T-C spacing with 5.25" drivers at this freq shouldn't be an issue anymore.
So what do you all think about this idea? Am I finally on the right track this time?
Auplater, very nice work! Would love to see what the rest of the setup looks like.
Bjorno, thanks for those simulations. Unfortunately, I'm not 100% certain of what I'm looking at, but I think I get the idea.
Anyway, I think I might have figured out a solution to this project...
First off, I'm going to scrap the entire idea of building the LA's with the Dayton Classic drivers. Not only are they too large, but they also have those midrange issues and will not match up to the Dayton planars properly.
So what I think I will do now is this...
I will buy a total of (20) GR M-130 drivers and a total of (15) Dayton PT2C-8 planars. The left and right channels will each have EIGHT woofers and SIX planars, the center channel will be exactly half with FOUR woofers and THREE planars.
This will keep me in budget (just over $1k for drivers alone), will provide better performance due to the better quality woofers, they are smaller and their C-T-C will be closer allowing for a higher xover freq to match up with the planars (2kHz), will be a nominal 4 ohms for the main channels (nominal 8 ohms for the center channel), the main channels will probably extend down into the mid-30's pretty well, and will be like the smaller, cheaper baby brother of the GR LS-6. :thumb:
From the looks of the plot on GR's website for the M-130, even off axis, a 2kHz xover point looks to be well within reach as the driver seems to be flat at 2kHz. Since if I am staying with the Dayton planars due to their price and performance, I am stuck with a minimum xover point of 2kHz and from what I gather, C-T-C spacing with 5.25" drivers at this freq shouldn't be an issue anymore.
So what do you all think about this idea? Am I finally on the right track this time?
Wavebourn said:
Stereo imaging has nothing to do with needing a center channel or not. A center channel is required regardless of the quality of the main channels for proper dialog playback in movies.
Side and back surrounds are not an "initial idea" that will eventually fail either. They are required for proper playback of movies. Again, they have absolutely nothing to do with the quality of the main channels.
Besides, I have already answered my own center channel question in my previous post above.
rest of setup
http://www.diyaudio.com/forums/showthread.php?s=&threadid=95603&highlight=
sub woofers..
C-T-C @ 5 1/2" will be asmaller issue at 2 Khz for sure... it's just whether or not you'll hear the lobing. It will definitely be an improvement over the 6 1/2" 'ers, though. wavelength @ 2100 Hz ~ 6.5", and ideally you'd like to keep the ctc distance well below that... to minimize irregular response... that's the problem
Jim Griffin's paper on the subject...
http://www.audiodiycentral.com/resource/pdf/nflawp.pdf
John L.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=95603&highlight=
sub woofers..
C-T-C @ 5 1/2" will be asmaller issue at 2 Khz for sure... it's just whether or not you'll hear the lobing. It will definitely be an improvement over the 6 1/2" 'ers, though. wavelength @ 2100 Hz ~ 6.5", and ideally you'd like to keep the ctc distance well below that... to minimize irregular response... that's the problem
Jim Griffin's paper on the subject...
http://www.audiodiycentral.com/resource/pdf/nflawp.pdf
John L.
chops said:
The argument is that if you sit in the sweet spot whilst watching a movie and you also have mains that image well, then they should be able to throw a phantom image using the mono centre channel signal.
If these conditions are met, then its possible you could omit the centre and maybe even have a better system for it, the front sound stage would certainly be consistent.
center channel
Ant is on the money here. My setup images the vocal tracks very well indeed w/o a center speaker. However, I also use the speakers built into my display as the center channel, giving the versatility of independently "bringing them up" if necessary on less than ideal video material. An even greater advantage of no default center channel is improved music reproduction in systems doing dual duty (as mine does)... you don't have to screw around with synthetic dsp modes and such when listening only.
With my recently acquired 7.1 channel Denon, I've managed to replace all the other gear and greatly simplify the operation of all the uses for this room (not to mention the rats nest of wiring behind the stack)
I'm getting too old to tolerate constantly switching cords, etc....
John L.
ShinOBIWAN said:
Ant is on the money here. My setup images the vocal tracks very well indeed w/o a center speaker. However, I also use the speakers built into my display as the center channel, giving the versatility of independently "bringing them up" if necessary on less than ideal video material. An even greater advantage of no default center channel is improved music reproduction in systems doing dual duty (as mine does)... you don't have to screw around with synthetic dsp modes and such when listening only.
With my recently acquired 7.1 channel Denon, I've managed to replace all the other gear and greatly simplify the operation of all the uses for this room (not to mention the rats nest of wiring behind the stack)
I'm getting too old to tolerate constantly switching cords, etc....
John L.
Nice project! And somewhat challenging as well, given your budget constraints. Some comments:
1) Given that you will use the DCX2496 as an active x-over I would not bother with impedance-flattening. As long as you take the time to measure the response of your implementation any deviations due to changes in impedance can easily be corrected with the EQ of the DCX. This will also keep passive components out of the path of these drivers, bettering amp control over them. And, at least if fed by a 24/96 source (using the SRC2496 as a frontend will achieve this) the DCX is highly transparent even at quite high levels of EQ'ing.
2) Although the M130 and PT2 combination should work well, you should try to avoid cutting the length of the lines from your suggestion of (at least) 12 + 8 per channel. To achieve line source behavior at lower frequencies (which you will want) your woofer-line should cover about 70% of the floor-ceiling distance if possible. Also, experience seems to indicate that using tweeter-lines of about the same length as the woofer-line leads to a more 'right' sounding array (probably due to a better balance in frequency response between direct and in-direct radiation).
3) The center channel is tricky, and you may be better off leaving that for later. This is because: a) Going with PT2 mounted horizontally you will want a line that is at least as wide as the width of seating for viewers = a very large center, b) Mounting it vertically you can only use 1 tweeter (which, in the case of the PT2 will have to be crossed quite high to keep up in terms of demanded SPL), more than that will get you in serious trouble in terms of cancellations at certain frequencies, and c) You may not need one as the sweet-spot of the arrays will be a lot larger than what you are used to. This is particularly true if you angle them quite aggressively (crossing in front of listening position could work out well) as this will better balance the relative SPL of the two speakers when you move to the side.
Any way - good luck with the project! Although there are some challenges to overcome I think the end-result can turn out great!
-A
1) Given that you will use the DCX2496 as an active x-over I would not bother with impedance-flattening. As long as you take the time to measure the response of your implementation any deviations due to changes in impedance can easily be corrected with the EQ of the DCX. This will also keep passive components out of the path of these drivers, bettering amp control over them. And, at least if fed by a 24/96 source (using the SRC2496 as a frontend will achieve this) the DCX is highly transparent even at quite high levels of EQ'ing.
2) Although the M130 and PT2 combination should work well, you should try to avoid cutting the length of the lines from your suggestion of (at least) 12 + 8 per channel. To achieve line source behavior at lower frequencies (which you will want) your woofer-line should cover about 70% of the floor-ceiling distance if possible. Also, experience seems to indicate that using tweeter-lines of about the same length as the woofer-line leads to a more 'right' sounding array (probably due to a better balance in frequency response between direct and in-direct radiation).
3) The center channel is tricky, and you may be better off leaving that for later. This is because: a) Going with PT2 mounted horizontally you will want a line that is at least as wide as the width of seating for viewers = a very large center, b) Mounting it vertically you can only use 1 tweeter (which, in the case of the PT2 will have to be crossed quite high to keep up in terms of demanded SPL), more than that will get you in serious trouble in terms of cancellations at certain frequencies, and c) You may not need one as the sweet-spot of the arrays will be a lot larger than what you are used to. This is particularly true if you angle them quite aggressively (crossing in front of listening position could work out well) as this will better balance the relative SPL of the two speakers when you move to the side.
Any way - good luck with the project! Although there are some challenges to overcome I think the end-result can turn out great!
-A
Chops,
I've kept an eye on your thread from the start but didn't want to try to sway you from the Dayton 6.5s since you seemed to like them so much. Now that you are looking to other options and smaller woofers, I think you should look at the drivers here.
Particularly, look at the 5.25" peerless woofers.
Similar specs to the M-130, but not quite as much x-max. Has the advantage of shorting rings and probably lower distortion over the M-130. It was crossed over to at 2.5kHz in the NHT speakers it was used in, so it should be easy enough to cross over.
The best advantage it has is price, 10 bucks apiece for what would have been a $40 woofer. If I were building a line array (wish I could right now, I'd love to try one) those are the woofers I would use.
Good luck with the project!
Regards,
David
I've kept an eye on your thread from the start but didn't want to try to sway you from the Dayton 6.5s since you seemed to like them so much. Now that you are looking to other options and smaller woofers, I think you should look at the drivers here.
Particularly, look at the 5.25" peerless woofers.
An externally hosted image should be here but it was not working when we last tested it.
Similar specs to the M-130, but not quite as much x-max. Has the advantage of shorting rings and probably lower distortion over the M-130. It was crossed over to at 2.5kHz in the NHT speakers it was used in, so it should be easy enough to cross over.
The best advantage it has is price, 10 bucks apiece for what would have been a $40 woofer. If I were building a line array (wish I could right now, I'd love to try one) those are the woofers I would use.
Good luck with the project!
Regards,
David
Hey David, thanks for the info. However, I think I have been talked into upgrading even higher and going with the M-130X drivers! 
There's no doubt I'm going to be putting some major cash into this project, and at this point I am willing to do so as long as the money is there to allow me. If the few things I have up for sale actually sell, then I should be fine with funds for the project.
If things go south as far as the sale items are concerned, I'll definately look into the drivers you mentioned. In fact, I saved the link to that page you linked to!
Again, thanks!
There's no doubt I'm going to be putting some major cash into this project, and at this point I am willing to do so as long as the money is there to allow me. If the few things I have up for sale actually sell, then I should be fine with funds for the project.
If things go south as far as the sale items are concerned, I'll definately look into the drivers you mentioned. In fact, I saved the link to that page you linked to!
Again, thanks!
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