Hi all. After hearing such good reviews of the Dayton Reference Series, and after trying my first open baffle build using some vifa buyout 7"ers and a the tangband 1-1/8" tweeter (just what I had lying around) I was hooked and impressed and got to thinking I'd like to try a serious open baffle project. I sort of just threw this system together for minimal cost and because I was getting bored and hadn't done any builds in a bit.
I've been thinking about the 7" reference series because of their long x-max over the 6"ers. The system will be completely equalized using a behringer DEQ so the good linearity of the daytons coupled with the 7" good xmax should be a good combo for relatively low frequency extension with good linearity and low distortion.
So I've been pondering an MTM Open Baffle with the 7"ers and some Morel MDT30s (I already have the Morels). Now I've been hearing above 1.5KHz is a sort of no-go with the 7"er so it looks like I'd either have to really push the Morel's with a "conventional" L/R 4th order. However on a discussion on another forum, I came across a few fellows discussing elliptical filters for the dayton 8" reference in a two way. They planned on pairing the 8" with some Seas Millenium Excels with a crossover frequency around 1KHz. I don't have any where near the $ for these tweeters and I love the morels. So I'm thinking of giving the morels and the 7"ers a try with the an elliptical filter such as the one discussed at the link posted on the bottom of this post. Anyone have any ideas/suggestions/impressions. I know the MDT30 has a bit of a large faceplate so I was planning on offsetting it on the baffle to get the two woofers closer.
I'm just really excited about trying the dayton reference series and am impressed with the sound an open baffle brings. Has anyone tried to mate the two yet?
http://ldsg.snippets.org/FILTERS/Cuadra/elliptic.php3
I've been thinking about the 7" reference series because of their long x-max over the 6"ers. The system will be completely equalized using a behringer DEQ so the good linearity of the daytons coupled with the 7" good xmax should be a good combo for relatively low frequency extension with good linearity and low distortion.
So I've been pondering an MTM Open Baffle with the 7"ers and some Morel MDT30s (I already have the Morels). Now I've been hearing above 1.5KHz is a sort of no-go with the 7"er so it looks like I'd either have to really push the Morel's with a "conventional" L/R 4th order. However on a discussion on another forum, I came across a few fellows discussing elliptical filters for the dayton 8" reference in a two way. They planned on pairing the 8" with some Seas Millenium Excels with a crossover frequency around 1KHz. I don't have any where near the $ for these tweeters and I love the morels. So I'm thinking of giving the morels and the 7"ers a try with the an elliptical filter such as the one discussed at the link posted on the bottom of this post. Anyone have any ideas/suggestions/impressions. I know the MDT30 has a bit of a large faceplate so I was planning on offsetting it on the baffle to get the two woofers closer.
I'm just really excited about trying the dayton reference series and am impressed with the sound an open baffle brings. Has anyone tried to mate the two yet?
http://ldsg.snippets.org/FILTERS/Cuadra/elliptic.php3
Dswiston, It's good to read of other people working on this sort of project. I just read a very interesting project liked from the PE forum- it's here http://www.mfk-projects.com/in_the_works.htm.
This gentleman's used two 7"s and two 10"s with an Usher tweeter using 4th order LR crossovers and the Behringer. It looks like there's more to it than that, but you're not alone in the idea.
I'd have a good thorough look over at Linkwitzlab.com to learn more of open baffle dipoles (i know i will before I spend money on drivers), but I believe that a wider (larger) baffle can improve the low-end max output of a dipole. This suggests to me that the 6" drivers could be acceptable in an MTM configuration if thier highpass is high enough; and they'll be more capable of crossing to your tweeters.
Your MDT30s can probably go fairly loud as you've used them before- but to push the crossover to its lower limits.... I guess that's just something to consider.
Please keep us updated on what you finally do! These drivers look quite interesting.
Joe
This gentleman's used two 7"s and two 10"s with an Usher tweeter using 4th order LR crossovers and the Behringer. It looks like there's more to it than that, but you're not alone in the idea.
I'd have a good thorough look over at Linkwitzlab.com to learn more of open baffle dipoles (i know i will before I spend money on drivers), but I believe that a wider (larger) baffle can improve the low-end max output of a dipole. This suggests to me that the 6" drivers could be acceptable in an MTM configuration if thier highpass is high enough; and they'll be more capable of crossing to your tweeters.
Your MDT30s can probably go fairly loud as you've used them before- but to push the crossover to its lower limits.... I guess that's just something to consider.
Please keep us updated on what you finally do! These drivers look quite interesting.
Joe
Thanks for the link! That fellow designing that particular project is crossing the daytons above 2KHz, and his distortion and stored energy plots are good to see. Maybe I can push the crossover to 1.8KHz or 2KHz.
BTW, I may have been unclear, but I'm not using the Behringer Crossover but the Ultra Curve Pro for equalization due to the inherent open baffle -6dB/octave bass response. I'm aiming for equalization down to about 80Hz or so, and I don't plan on having these speakers be SPL monsters, so thats why I'd like to use the 7"ers. I'm assuming the xmax/increased cone area will come in handy when equalizing.
BTW, I may have been unclear, but I'm not using the Behringer Crossover but the Ultra Curve Pro for equalization due to the inherent open baffle -6dB/octave bass response. I'm aiming for equalization down to about 80Hz or so, and I don't plan on having these speakers be SPL monsters, so thats why I'd like to use the 7"ers. I'm assuming the xmax/increased cone area will come in handy when equalizing.
dayton RS dipoles
rumor has it that darren from Parts Express is going to make a few RS driver more car audio friendly. some discussion on elite car audios forum darren posted, and asked would there be any interest in a 4ohm non-shielded (shallow) version of the RS drivers. Also, in the post was if a higher Qts design would be of interest to the car audio crowd?
from what i got the 6-7- and maybe 8inch Rs drivers will be tested soon and made 4ohm / with no magnet/shield and also of a higher Q
i would think for what your idea is dipole MTM with 7's this would be of some interest.
i have seen a few people talk about the need for EQ for the refraction of the drivers rear baskett, and the non shielded version would prolly help
just a idea, im holding out on the dayton RS drivers in hopes of the car audio specs, should be just what i need
rumor has it that darren from Parts Express is going to make a few RS driver more car audio friendly. some discussion on elite car audios forum darren posted, and asked would there be any interest in a 4ohm non-shielded (shallow) version of the RS drivers. Also, in the post was if a higher Qts design would be of interest to the car audio crowd?
from what i got the 6-7- and maybe 8inch Rs drivers will be tested soon and made 4ohm / with no magnet/shield and also of a higher Q
i would think for what your idea is dipole MTM with 7's this would be of some interest.
i have seen a few people talk about the need for EQ for the refraction of the drivers rear baskett, and the non shielded version would prolly help
just a idea, im holding out on the dayton RS drivers in hopes of the car audio specs, should be just what i need
what about the 6 inch? I think you might be able to cross it abit higher. Size wise it might be border line for open baffle but linkwitz measured afew 6.5 in drivers for use in open baffle so your pretty close. Maybe solicit opinions on that one from others here.
Are you really fixed on the dayton rs drivers. The peerless 850439 faired very well in linkwitz' distortion measurements, although is more expensive. I have heard on this forum that the csx drivers are very similar but with stamped frames. Perhaps the 6.5 in in that series would be suitable. 850122 i think.
I would like to see someone do an mtm open baffle along the lines of linkwitz with the peerless 850439 and post info but so far I haven't found anyone who's done it. There is the prototype on his site with the vifa p21 and passive xo but the vifa has worse distortion measurements then the peerless.
Anyone measured distortion of the dayton rs drivers in a meaningful way that can be compared to the linkwitz measurements?
Are you really fixed on the dayton rs drivers. The peerless 850439 faired very well in linkwitz' distortion measurements, although is more expensive. I have heard on this forum that the csx drivers are very similar but with stamped frames. Perhaps the 6.5 in in that series would be suitable. 850122 i think.
I would like to see someone do an mtm open baffle along the lines of linkwitz with the peerless 850439 and post info but so far I haven't found anyone who's done it. There is the prototype on his site with the vifa p21 and passive xo but the vifa has worse distortion measurements then the peerless.
Anyone measured distortion of the dayton rs drivers in a meaningful way that can be compared to the linkwitz measurements?
HIPCHECK:
Thanks for the info on the talks of new RS drivers. A non-shielded version would be a good thing, I have heard talk about the possible problems with the rear basket. That’s another reason why I thought the 7" driver might be better suited, the basket seems to take up less of the cone area than on the smaller drivers. My particular situation has two problems with waiting though. One is that having 4Ohm drivers would not allow an MTM configuration with the two woofers in parallel. The speaker impedance would be much to low. I am also very poor being in the third year of college, and these drivers were going to be on my Christmas list for my brother. Waiting to see what happens in regards to car audio versions won't be possible. However, thanks for the information, I will keep my eye out for possible new versions of the RS drivers in the future.
dvdwmth:
It is a tough decision between the two for me (6 vs 7). The only thing that keeps me thinking no to the 6" is that the amount of air the driver can move is not comparable to the 6.5" peerless HDS or CSX because each of the two peerless drivers has an xmax of 5.5mm compared to 4mm for the dayton. I just keep thinking that pushing the 6" driver with EQ will be too much for the driver, resulting in a much larger amount of non-linearity compared to the 7". I am however open to being convinced otherwise. Interestingly enough, I do already have a pair of speakers I designed with two of the CSX 6.5" drivers. They were actually my first pair of DIY speakers. I was impressed with the sound being that I had almost no idea what I was doing at the time. I however would like to try out the new RS series to see if they might become a new inexpensive favorite of mine.
Thanks for the info on the talks of new RS drivers. A non-shielded version would be a good thing, I have heard talk about the possible problems with the rear basket. That’s another reason why I thought the 7" driver might be better suited, the basket seems to take up less of the cone area than on the smaller drivers. My particular situation has two problems with waiting though. One is that having 4Ohm drivers would not allow an MTM configuration with the two woofers in parallel. The speaker impedance would be much to low. I am also very poor being in the third year of college, and these drivers were going to be on my Christmas list for my brother. Waiting to see what happens in regards to car audio versions won't be possible. However, thanks for the information, I will keep my eye out for possible new versions of the RS drivers in the future.
dvdwmth:
It is a tough decision between the two for me (6 vs 7). The only thing that keeps me thinking no to the 6" is that the amount of air the driver can move is not comparable to the 6.5" peerless HDS or CSX because each of the two peerless drivers has an xmax of 5.5mm compared to 4mm for the dayton. I just keep thinking that pushing the 6" driver with EQ will be too much for the driver, resulting in a much larger amount of non-linearity compared to the 7". I am however open to being convinced otherwise. Interestingly enough, I do already have a pair of speakers I designed with two of the CSX 6.5" drivers. They were actually my first pair of DIY speakers. I was impressed with the sound being that I had almost no idea what I was doing at the time. I however would like to try out the new RS series to see if they might become a new inexpensive favorite of mine.
it seems that you will be designing around alot of hurdles. I can see that the price is appealing but are you sure this is the right series of drivers to be looking at. Some of the comments you have made about the RS drivers seem to suggest that these are not appropriate for this application. Since you already have some peerless drivers that have been suggested by an authoritative source as worth considering it seems to me that the most sensible course would be to build an mtm with the peerless driver you already have two of, or just looking at another series of drivers all together.
On linkwitz's site he states the pmt1
http://www.linkwitzlab.com/proto.htm
using one vifa p21 is the smallest practical size for an OB speaker. I imagine if you get the data for air displacement of this speaker you would have a reasonable benchmark to compare other drivers you might be considering to. These considerations are linked to room size and loudness requirements so naturally you'll have to use this info in context of your own situation.
By the way, are you planning to do these passive or active?
On linkwitz's site he states the pmt1
http://www.linkwitzlab.com/proto.htm
using one vifa p21 is the smallest practical size for an OB speaker. I imagine if you get the data for air displacement of this speaker you would have a reasonable benchmark to compare other drivers you might be considering to. These considerations are linked to room size and loudness requirements so naturally you'll have to use this info in context of your own situation.
By the way, are you planning to do these passive or active?
Thanks for the additional link. I understand that the project has some hurdles, I do feel that the 7" driver has two possible downfalls. One is the driver's high frequency extension. It appears as though the crossover frequency will have to be rather low. I have already made an MTM speaker using the morel MDT30 crossed at 1800Hz using a 4th order L/R and it performs well. So I feel that if I invest my time into researching/designing higher order filters, a 1500Hz crossover frequency is obtainable while keeping the MDT30 happy and sounding nice. Secondly the backwave reflection caused by the magnet/sheilding structure might pose a problem but there is not much talk on the web yet that I could find dealing with this issue. However I enjoy the challenge and learning experience of working through such problems as I am still relatively new to this hobby.
The quality, linearity, and performance of the 7" mated with its displacement abilities makes me consider the woofer to be a good match for an MTM open baffle. The two peerless CSX woofers I currently have are also a good option, I 100% agree with you about that (although something tells me an MTM or TMM with the CSX drivers would be a much better idea). It makes it a tough call but something in me wants to try out the Daytons out of curiousity and a challenge is always welcome. Or since I already have the CSX drivers, maybe I'll just make a few test baffles and try out both.
BTW, to add to the mess, I also have a pair of MTM speakers using the exact same VIFA P21 as listed on the link you posted. Theoretically I could just design a new baffle, crossover, and give the vifa a try as an open baffle, but currently this speaker is my SPL monster (for when I feel like listening to music at a high volume), with VERY good bass extension in a sealed box actively equalized, so I do not want to give up such a pair of speakers for a new project.
Finally, I am planning on using a passive crossover. I do not have the equipment (amplifiers) to go completely active yet. I wil rely on the behringer for active equalization though.
The quality, linearity, and performance of the 7" mated with its displacement abilities makes me consider the woofer to be a good match for an MTM open baffle. The two peerless CSX woofers I currently have are also a good option, I 100% agree with you about that (although something tells me an MTM or TMM with the CSX drivers would be a much better idea). It makes it a tough call but something in me wants to try out the Daytons out of curiousity and a challenge is always welcome. Or since I already have the CSX drivers, maybe I'll just make a few test baffles and try out both.
BTW, to add to the mess, I also have a pair of MTM speakers using the exact same VIFA P21 as listed on the link you posted. Theoretically I could just design a new baffle, crossover, and give the vifa a try as an open baffle, but currently this speaker is my SPL monster (for when I feel like listening to music at a high volume), with VERY good bass extension in a sealed box actively equalized, so I do not want to give up such a pair of speakers for a new project.
Finally, I am planning on using a passive crossover. I do not have the equipment (amplifiers) to go completely active yet. I wil rely on the behringer for active equalization though.
http://home.comcast.net/~dreite/Davey/Davey.JPG
IMHO the Dayton RS drivers are not suitable for dipole usage. A much too large a magnet/basket assembly blocks the side/rear radiation quite a bit. I think the baskets of the Seas drivers are better and the polar response can be made fairly adequate with a non-complicated baffle shape.
You might want to consider the Seas CA18RLY drivers for an MTM configuration dipole setup. I used two of those and a 27TDFC per side to mate with 850146 woofers. The mid/tweet crossover is passive and the sensitivities of these drivers are nearly perfect to support a parallel connection of the CA18 drivers with no pad on the tweeter. A dedicated active crossover/EQ for the woof/mid crossover and you have an excellent dipole system for approximately $650.00.
Cheers,
Davey.
IMHO the Dayton RS drivers are not suitable for dipole usage. A much too large a magnet/basket assembly blocks the side/rear radiation quite a bit. I think the baskets of the Seas drivers are better and the polar response can be made fairly adequate with a non-complicated baffle shape.
You might want to consider the Seas CA18RLY drivers for an MTM configuration dipole setup. I used two of those and a 27TDFC per side to mate with 850146 woofers. The mid/tweet crossover is passive and the sensitivities of these drivers are nearly perfect to support a parallel connection of the CA18 drivers with no pad on the tweeter. A dedicated active crossover/EQ for the woof/mid crossover and you have an excellent dipole system for approximately $650.00.
Cheers,
Davey.
Davey,
Have you tested the RS, or are you just making an assumption based on the geometry.
From a distortion standpoint these drivers are in the same league as the Seas, besting even some of the excel.
In addition, the vent noise is very well controlled.
I can't comment on the rear response, but in many other respects these drivers outperform the competition.
The RS10" might have been a better choice than the peerless in your open baffle design than the peerless-I know since I've tested both
I can't comment on the CA18's. They're probably pretty nice.
The open basket of the Seas, and the metal seas cones are impressive, but the motor itself of the RS series is quite good. I would not rule these out without testing them first.
http://206.13.113.199/ncdiyaudio/mark/index.htm
Have you tested the RS, or are you just making an assumption based on the geometry.
From a distortion standpoint these drivers are in the same league as the Seas, besting even some of the excel.
In addition, the vent noise is very well controlled.
I can't comment on the rear response, but in many other respects these drivers outperform the competition.
The RS10" might have been a better choice than the peerless in your open baffle design than the peerless-I know since I've tested both
I can't comment on the CA18's. They're probably pretty nice.
The open basket of the Seas, and the metal seas cones are impressive, but the motor itself of the RS series is quite good. I would not rule these out without testing them first.
http://206.13.113.199/ncdiyaudio/mark/index.htm
Mark, I think you've got some really cool stuff on your page! Is there any chance that we'll see more soon? Perhaps a description of your own setup, or plans if you're building one?
I'm still considering an Orion/Pheonix- like project, and the idea that it might be possible to get drivers worthy of comparison for around $450, use a computer (already own it, and will be in the listening room anyway), a $45 sound card with kxpro for crossovers, and 6 channels of battery powered gainclones- well, that's very very exciting to me.
Can anybody on this forum quantify how big of a problem it is that the Dayton RS drivers have such large magnets? I've been looking at frequency response, distortion, sensitivity, power handling, cost, etc- and if "magnet reflection" is not a big deal- these drivers look phenomenal. (provided you use a steep crossover, and possibly a notch filter)
I've heard it before, and though I forget where I read it- I will agree that an unshieled version of the Dayton RS series would be quite welcome especially if it costs less. Better still would be a neodymium shielded version similar to the Adire Extremis for just a little more.
I'm still considering an Orion/Pheonix- like project, and the idea that it might be possible to get drivers worthy of comparison for around $450, use a computer (already own it, and will be in the listening room anyway), a $45 sound card with kxpro for crossovers, and 6 channels of battery powered gainclones- well, that's very very exciting to me.
Can anybody on this forum quantify how big of a problem it is that the Dayton RS drivers have such large magnets? I've been looking at frequency response, distortion, sensitivity, power handling, cost, etc- and if "magnet reflection" is not a big deal- these drivers look phenomenal. (provided you use a steep crossover, and possibly a notch filter)
I've heard it before, and though I forget where I read it- I will agree that an unshieled version of the Dayton RS series would be quite welcome especially if it costs less. Better still would be a neodymium shielded version similar to the Adire Extremis for just a little more.
Mark,
No, I haven't tested the RS drivers, but you may be correct. The only way to really tell is to mount on a few test baffles and check the polar response. 'Kind of a tedious process. I'm speculating on the RS drivers based on the geometry of the rear basket and mounting into 3/4 inch material. They look pretty constrictive to me.
The RS 10" driver has Xmax of only 6.5mm and the Peerless 850146 has an Xmax of 9mm. I think 9mm is already marginal considering the SPL capability of the rest of the system. I don't think the 850146 was a bad choice, but there could be some better ones. It doesn't appear the RS 10-inchers are suitable though unless the EQ or SPL capability is relaxed. I'm puzzled why Monte Kay chose these for his design. Maybe he got caught up in all the buzz these drivers are creating? They appear to be terrific drivers for a value project....but just not for a dipole project.
Cheers,
Davey.
No, I haven't tested the RS drivers, but you may be correct. The only way to really tell is to mount on a few test baffles and check the polar response. 'Kind of a tedious process. I'm speculating on the RS drivers based on the geometry of the rear basket and mounting into 3/4 inch material. They look pretty constrictive to me.
The RS 10" driver has Xmax of only 6.5mm and the Peerless 850146 has an Xmax of 9mm. I think 9mm is already marginal considering the SPL capability of the rest of the system. I don't think the 850146 was a bad choice, but there could be some better ones. It doesn't appear the RS 10-inchers are suitable though unless the EQ or SPL capability is relaxed. I'm puzzled why Monte Kay chose these for his design. Maybe he got caught up in all the buzz these drivers are creating? They appear to be terrific drivers for a value project....but just not for a dipole project.
Cheers,
Davey.
Mark, if I'm correct I've seen you on a forum I frequent much less often post about the RS drivers prior. Are you/have you tried the drivers in an open baffle configuration? Is it fesible to test the rear response in a meaningful way? If it is true that the rear assembly would hinder rear response and cause the speakers to perform very poorly in an OB, I'd really like to know.
Davey, thanks for the tip on the Seas. I fear that four of the drivers are closing in on out of my budget range currently. Unless someone wants to donate to a poor college student =) Also thanks for raising the question about the rear response. I did not realize that it might pose such a large problem for an OB, although reflecting on how an OB works, it makes sense. The real question becomes is there a problem or not.
If Mr. Monte Kay is lurking around here, please feel free to chime in with your RS experience. I noticed you are very impressed with them and are building an MTM open baffle with them. I'd not only be interested with any measurements, but the crossover design as well.
For anyone interested his webpage w/the project is here at this link:
http://www.mfk-projects.com
*EDIT I couldn't find how to get to this page from the main page so I'll post the link to the project as well:
http://www.mfk-projects.com/in_the_works.htm
Davey, thanks for the tip on the Seas. I fear that four of the drivers are closing in on out of my budget range currently. Unless someone wants to donate to a poor college student =) Also thanks for raising the question about the rear response. I did not realize that it might pose such a large problem for an OB, although reflecting on how an OB works, it makes sense. The real question becomes is there a problem or not.
If Mr. Monte Kay is lurking around here, please feel free to chime in with your RS experience. I noticed you are very impressed with them and are building an MTM open baffle with them. I'd not only be interested with any measurements, but the crossover design as well.
For anyone interested his webpage w/the project is here at this link:
http://www.mfk-projects.com
*EDIT I couldn't find how to get to this page from the main page so I'll post the link to the project as well:
http://www.mfk-projects.com/in_the_works.htm
Davey,
Despite the 9mm xmax published for the Peerless, it seems to fare no better than the RS10, perhaps slighly worse. Though this is probably too close to call from the limited data I show on my site. One could then argue about basket geometry etc. I will say, audible vent noise could be heard from the Peerless at a lower level than the RS10. Still, they're very close and they're about the same price.
dwist,
I haven't looked at dipole configurations for this driver, so it's generally hard to comment specifically. It is possible the rather large magnet assembly could cause a problem, but I wouldn't rule it out. After all, John K's NaO uses the SS drivers, which have a hefty magnet, and SL's Phoneix used the SS as well. Remember, we're talking a budget design here.
My main point is that, without some thoughful testing, there is no clear answer.
I will say I'm very impressed with Davey's design. I'm glad that we're finally seeing some well though out budget designs coming out in a dipole configuration.
Will I do a dipole? Yea, probably. But it will probably take me a year or two. I'm in no rush, have other projects, and also really want to understand what I'm doing. So, it will take some time.
I still have some traditional 3 ways to finish.
Despite the 9mm xmax published for the Peerless, it seems to fare no better than the RS10, perhaps slighly worse. Though this is probably too close to call from the limited data I show on my site. One could then argue about basket geometry etc. I will say, audible vent noise could be heard from the Peerless at a lower level than the RS10. Still, they're very close and they're about the same price.
dwist,
I haven't looked at dipole configurations for this driver, so it's generally hard to comment specifically. It is possible the rather large magnet assembly could cause a problem, but I wouldn't rule it out. After all, John K's NaO uses the SS drivers, which have a hefty magnet, and SL's Phoneix used the SS as well. Remember, we're talking a budget design here.
My main point is that, without some thoughful testing, there is no clear answer.
I will say I'm very impressed with Davey's design. I'm glad that we're finally seeing some well though out budget designs coming out in a dipole configuration.
Will I do a dipole? Yea, probably. But it will probably take me a year or two. I'm in no rush, have other projects, and also really want to understand what I'm doing. So, it will take some time.
I still have some traditional 3 ways to finish.
Yeah, I noted the 10" woofer data on your site previously. The Dayton may have been a better choice, but the Peerless seems to work well in this case.
If I send you one of my spare CA18RLY drivers will you include it in your next round of tests? I think having published data of the relative differences between drivers performed by a single individual is an excellent resource for we DIY'ers. Thanks much.
John K. used both the W18E and SS8545 in his NaO design, but I'm not sure if he investigated horizontal polar response with the baffles he tried. The different Seas drivers W18, CA18, etc all have slightly different magnet sizes but the basket assembly is the same with the large diameter spider. The magnet on the CA18RLY is actually quite small compared to the others, but I'm not sure how much of a factor that is. John K's objective with the U-frame woofer is to promote a more directional pattern so maybe this was his objective with the mid-panel as well...I'm not sure.
The problem with using 7" drivers is that they all look fairly constricted relative to some of the 8" drivers. When you rabbet them into 3/4" material it's hard to conclusively tell how much the response will be affected without some experimentation/testing. Keep in mind that any non-uniform characteristics of the polar response at various angles can not be EQ corrected without affecting the on-axis response. The only option is to revamp the baffle shape. How much this non-uniform response factors into the overall performance of the system is unclear to me, but it's something to be aware of. The baffle I used for my system is just a simple piece of 3/4" plywood with no bracing or side pieces on the rear. I attached a few different side pieces to see if I could improve the response, and I succeeded to a degree, but I'm not sure how much the improvement would audibly improve the system. I decided to keep the construction as simple as possible.
Cheers,
Davey.
If I send you one of my spare CA18RLY drivers will you include it in your next round of tests? I think having published data of the relative differences between drivers performed by a single individual is an excellent resource for we DIY'ers. Thanks much.
John K. used both the W18E and SS8545 in his NaO design, but I'm not sure if he investigated horizontal polar response with the baffles he tried. The different Seas drivers W18, CA18, etc all have slightly different magnet sizes but the basket assembly is the same with the large diameter spider. The magnet on the CA18RLY is actually quite small compared to the others, but I'm not sure how much of a factor that is. John K's objective with the U-frame woofer is to promote a more directional pattern so maybe this was his objective with the mid-panel as well...I'm not sure.
The problem with using 7" drivers is that they all look fairly constricted relative to some of the 8" drivers. When you rabbet them into 3/4" material it's hard to conclusively tell how much the response will be affected without some experimentation/testing. Keep in mind that any non-uniform characteristics of the polar response at various angles can not be EQ corrected without affecting the on-axis response. The only option is to revamp the baffle shape. How much this non-uniform response factors into the overall performance of the system is unclear to me, but it's something to be aware of. The baffle I used for my system is just a simple piece of 3/4" plywood with no bracing or side pieces on the rear. I attached a few different side pieces to see if I could improve the response, and I succeeded to a degree, but I'm not sure how much the improvement would audibly improve the system. I decided to keep the construction as simple as possible.
Cheers,
Davey.
dswiston said:
Have you looked closely at the pheonix XO. I know you don't want to go active, but these xo at 1400khz and might be the answer to your problems. I have no idea how to adapt the eq to the rs drivers though.
Using chip amps you can keep the cost of the extra amplifiers down. I usually spend about $25/channel provided I can find suitable transformers at the surplus shop which so far hasn't been a problem.
Thanks for the tip. I'm planning on using the 7" (RS180) so I would only assume that its cone breakup is a bit higher than the 8" version. From staring at the PE plot, it looks like just above 2k has a slight bump, so maybe thats the first cone breakup mode. Also, MTMs benefit from the lowest possible xover frequency, so the lower the better.
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