Hi,
I have no science or test data that will back this response so it's purely subjective.
[*]I'm wondering what the differences in sound between the Deltalites compared to higher qts drivers (Alpha 15A's, GRS, etc)? I assume with the Deltalites it might be cleaner and a tad leaner than higher qts drivers?
- I wasn't sure how low the NEO8-PDR line could be driven in OB so there was a chance the woofer array might be playing up to 500hz. I've had the Alpha/GRS/Goldwood OB drivers in a different application running up to 500hz. I liked the sound of the Deltalite running in that frequency range better than the others mentioned. Low frequency was harder to pic a winner assuming excursion wasn't the deciding factor.
[*]How would a coaxial type setup with 5.25 to 8" drivers flanking the tweeter line be different in sound?
- I wanted a OB setup for a large portion of the frequency range. If a coaxial design is intended then the front (tweeter) LA would/should be sealed configuration. Not sure what effect having essentially a wall right behind the HF array would do to the dipole radiation or presentation in the listening position.
[*]What effects does a coaxial OB LA type setup have on lobing and comb filtering?
- With small format sealed midrange/tweeter array being flanked by an OB woofer array, I can see this working our rather nicely. I wanted to try this too. Maybe my next build
. I was looking into the small full range AURA drivers, I think they were the whispers NSW1-205-8A. Those in a LA in a sealed arrangement flanked by a OB woofer array coming in below the schroeder frequency of the room might be something very special.If you ask the specialists there is a definition difference between lobing and comb filtering. I wanted the midrange panel to be within 1/4 wavelength of the woofer panel since the drivers are located side by side instead of vertical. Same issues as a regular speaker but the axis will be flipped.
I used rectangular drivers to try and minimize vertical dispersion of elements in the LA. To my ears my LA doesn't sound worse or better in the HF than my point source speakers with drivers located vertically. The Jim Griffin LA white paper suggests a shaded array to combat comb filtering in a straight array but I suspect the CBT handles this issue better. I did not want to go with the CBT for this one.
[*]Why the GRS Slims vs the regular 8s? The distortion plots looked better on the reg 8's.
- I'm using the BG NEO8-PDR not the GRS slims. I did this build before the GRS was available. The BG might play a litter lower than the GRS slims but if I was going to use the GSR drivers, I would use the slims as they seem to have better horizontal dispersion. I managed to get the BG NEO8-PDR before the price increase.
I'm still using this setup and have no bug to change at the moment. They still perform well and have me smiling on a daily basis!! Your speakers goals may be different though. I had very specific objectives/goals going into this build so yours might be different. LA are a lot of manual work and are costly.
Hey mlee, I finally ran some FR sweeps on the Dayton PT-mini6 planar tweeters bought on your recommendations. I can say without a doubt you are using them the right way, crossing as high as you do (10kHz, right?).
At ~102 dB/1m, THD is 0.75% at 10kHz, but rises pretty quickly. By 6k, it's up to 4% and hits a peak of 8% at 4 kHz.
I know -- 102 dB/1m is way louder than you usually have it. At 93 dB/1m, the 10kHz THD is just 0.2%.
You only hear these tweeters in their most well-behaved band.
I'd love to hear them some time -- after we're all vaccinated, right?!
At ~102 dB/1m, THD is 0.75% at 10kHz, but rises pretty quickly. By 6k, it's up to 4% and hits a peak of 8% at 4 kHz.
I know -- 102 dB/1m is way louder than you usually have it. At 93 dB/1m, the 10kHz THD is just 0.2%.
You only hear these tweeters in their most well-behaved band.
I'd love to hear them some time -- after we're all vaccinated, right?!
Thanks! Yes they are crossed around 10khz and have very wide horizontal dispersion. Of course with 24 of them per side you can use them a bit lower.......around 5khz or so. Almost don't need them but they do add that extra something the NEO8-PDR doesn't have in that last octave. They work really well in the 8kz to 20khz range if you can live with the vertical dispersion limitation.
Yes once we get the vaccine hopefully its happy listening time. Your welcome to take a listen at your volume levels hehe.
Thanks for the responses to the questions. I've really enjoyed reading about your projects!
I've been a long time fan of line sources/arrays ever since owning some newform ribbon speakers and researching the acoustic properties / benefits of LA's. Plus, some of the work StigErik has done with the BG / dipole project was very inspiring.
With the GRS slims, I'm looking to do a mixed HT LCR / studio setup built into a front baffle wall with an AT 2:35 screen.
I understand the benefits of floor to ceiling LA's but what are the consequences of truncated arrays to fit behind an AT PJ screen?
I'm looking at using the Alpha 15's for a coaxial type LA setup with the slims potentially backed with felt/absorption, or smaller 4-8" woofers flanking the GRS slims. Low end will be augmented by 4 subwoofers. Active DSP will be used as well as proper acoustic room treatment in a dedicated room.
I'm liking the idea of less work with the coax 15's setup, especially if I create smaller in-wall LAs for the surrounds, plus the deeper frequency extension could be a plus if needed afforded by the 15's. But, the potential "cleaner / tighter" sound of smaller flanking woofers may be a bigger benefit??
Sorry in advance, not trying to hijack this thread just wanted to get feedback from folks directly experienced with LA's. Should I create a new one?
I've been a long time fan of line sources/arrays ever since owning some newform ribbon speakers and researching the acoustic properties / benefits of LA's. Plus, some of the work StigErik has done with the BG / dipole project was very inspiring.
With the GRS slims, I'm looking to do a mixed HT LCR / studio setup built into a front baffle wall with an AT 2:35 screen.
I understand the benefits of floor to ceiling LA's but what are the consequences of truncated arrays to fit behind an AT PJ screen?
I'm looking at using the Alpha 15's for a coaxial type LA setup with the slims potentially backed with felt/absorption, or smaller 4-8" woofers flanking the GRS slims. Low end will be augmented by 4 subwoofers. Active DSP will be used as well as proper acoustic room treatment in a dedicated room.
I'm liking the idea of less work with the coax 15's setup, especially if I create smaller in-wall LAs for the surrounds, plus the deeper frequency extension could be a plus if needed afforded by the 15's. But, the potential "cleaner / tighter" sound of smaller flanking woofers may be a bigger benefit??
Sorry in advance, not trying to hijack this thread just wanted to get feedback from folks directly experienced with LA's. Should I create a new one?
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Lots to unpack here!!!! Posting here is more than ok.
Thanks!!! Mine were a lot of work but I do really enjoy them. A bit more background on my system and then I could comment on your proposed setup, although I have not implemented a truncated array in any space so I'd ultimately be guessing. I almost bought 4 newform ribbon but could not get off axis measurements for them so couldn't justify the price to try them out.
For my current setup I've spent a lot of time A/Bing the difference of having my PT-mini array integrated or just the NEo8-PDR running to 20khz. There is very little difference after everything has been optimized and I think I'd have trouble telling them apart unless I really paid attention during an A/B comparison. If I just had to just guess to what I'm listening to I'm not sure I'd be able to tell the difference. So with that said I think the GRS slim would be a good driver to use in your proposed Coaxial design with no tweeter line.
Just thinking out loud but I like your coaxial proposed design idea. I almost want to try that but it will be a lot of work for me. I'm assuming some very heavy foam on the back of the GRS drivers to try an minimize the rear firing SPL of the LA. Again, not sure if that will be a problem or not. Something tells be a small encloser for the GRS LA might not perform as good as your proposed foam but it would be nice to get them in a sealed enclosure to ensure the rear wave does not cause problems although that causes depth problems (CTC spacing issue) for the larger drivers.
If going coaxial I'd use the larger drivers as the CTC spacing will be pretty close. Assuming your crossing around 500hz I believe that is around 6.75" to 7" for the 1/4 wavelength CTC spacing in hopes to minimize crossover issues. If you can get the both LA lines close together then this should be doable but I'd check the depth of the cone for the large drivers to ensure you are close to this requirement. I've always liked the presentation of the larger drivers below 400hz than multiple smaller ones. No science to back that up though, your experience might be different. I'm assuming the larger drivers will be sealed (but maybe not?). I would probably use different drivers than the Alpha 15 since you might be going up higher in frequency than I'd like with that driver. Also the Q is pretty high for sealed but EQ might be able to tame the peak in response. I've not played with the Alpha in a sealed config so I don't know what it might sound like in that application running at 500hz. I'd use a driver with a lower q for sealed. If doing infinite baffle then it might be ok but I do like other drivers better as outlined in a previous post. I might be in the minority but my experience has been I have better luck with the larger drivers in the 400hz and below range. The smaller drivers always sound small for some reason but I might be listening with my eyes an not my ears?
If going side by side LA GRS slim and smaller drivers, I'd go with a single line of like 5.5" or 6.5" drivers to adhere to 1/4 CTC spacing at crossover. I get picky about this as you have to be careful with lobing. The lobing radiation pattern in the horizontal plane "might" be an issue in your room, but it might not. Tough to say but your proposed driver selection could eliminate a potential issue before it is a problem, then why not?
Regarding the truncated arrangement......as you know the floor to ceiling LA kindof depends on the ceiling and floor boundary image to perform optimally (ignoring frequency shading) so I'm guessing you might get a presentation a bit like increased floor/ceiling bounce as compared with a full floor to ceiling array. This might not be a problem if you are handling the floor and ceiling bounces and lots of people have point source speakers that don't deal with this issue and it still sounds great. Tough to really make any concrete assumptions without building it and comparing in your specific room. Some people claim a truncated LA will enlarge the sonic image. I don't have experience with that as I've never heard one. The closest I've heard is the maggie 1.6 but that was with unfamiliar music and a quick 15 min session.
I wish I had the screen to do a proper center channel. Let me know where your build thread is located as I'd be interested in hearing your impressions of your proposed LCR setup. I think either setup could be more than satisfactory.
Last note.................if I had a choice I'd see if I could get the coaxial implementation working. Less holes to cut/wire and I do like those large driver sonic presentations!
Thanks! Based on the feedback I'm leaning more towards larger drivers in a coaxial setup. Worse case scenario, I can still do a side by side setup with both LA elements.
I'm still wondering what large woofers would give the best presentation for ~50 to ~700hz for around $100 each. May bite the bullet if the Deltalites are the best option out of these OB woofers also suggested in another thread:
"Peerless SLS 830669. Clean, medium efficiency and good xmax. Easy to use.
SB Audience Bianco 120B150. Similar to the Peerless above. A bit more money.
Parts Express GRS 15. Excellent OB qualities and bang for the buck.
PRV 15W700. Good build quality. Large displacement. Must get out by 350 Hz.
Goldwood GW-1858. Lots of grunt down low. Great in parallel pairs.
PE - Dayton PA400. QTS is a bit low but well built and with nice roll off. Also good in a parallel dual format.
Peerless FSL-1830R06-08. Tremendous output, especially if used in parallel pairs. Midium QT. But must be out by 300 Hz."
So far idea is;
SPL goal is to get to Atmos reference levels across the board
I'm still wondering what large woofers would give the best presentation for ~50 to ~700hz for around $100 each. May bite the bullet if the Deltalites are the best option out of these OB woofers also suggested in another thread:
"Peerless SLS 830669. Clean, medium efficiency and good xmax. Easy to use.
SB Audience Bianco 120B150. Similar to the Peerless above. A bit more money.
Parts Express GRS 15. Excellent OB qualities and bang for the buck.
PRV 15W700. Good build quality. Large displacement. Must get out by 350 Hz.
Goldwood GW-1858. Lots of grunt down low. Great in parallel pairs.
PE - Dayton PA400. QTS is a bit low but well built and with nice roll off. Also good in a parallel dual format.
Peerless FSL-1830R06-08. Tremendous output, especially if used in parallel pairs. Midium QT. But must be out by 300 Hz."
So far idea is;
- OBLA w/ optional back absorber for (6) 8" GRS Slims placed in front of the woofers.
- OBLA for 3-4 TBD (12"-21") woofers for LCR's
- (4) TBD IB/Boxed subwoofers placed in the lower and upper corners.
SPL goal is to get to Atmos reference levels across the board
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That looks pretty cool! Can't wait to see em.
Its tough to see from the pics but are your LCR OBLA running OB away from the wall? If yes how far? Or are they going to run as IB?
Since you are running dedicated subs you don't have to reach down as far. I be tempted to do the SB. Nice efficiency and should be good in the intended frequency range. I like the QTS and as a last resort, you could do sealed if needed, keeps the options open.
Since you are running dedicated subs, you should be able to reach the dolby spec with most of the drivers listed. I like the pro drivers as they will take a beating and are higher efficiency.
Its tough to see from the pics but are your LCR OBLA running OB away from the wall? If yes how far? Or are they going to run as IB?
Since you are running dedicated subs you don't have to reach down as far. I be tempted to do the SB. Nice efficiency and should be good in the intended frequency range. I like the QTS and as a last resort, you could do sealed if needed, keeps the options open.
Since you are running dedicated subs, you should be able to reach the dolby spec with most of the drivers listed. I like the pro drivers as they will take a beating and are higher efficiency.
IB is a different beast than OB. I've not had the pleasure of listening to an all IB installation. From what I've read there are a lot of advantages to that.
One of the things I like about OB is the lack of impact in the bass in my room when the volume goes up. Some people like that, others don't like it at all. It is a personal presentation/preference choice. Not sure where you sit on that front.
It might be easier to lock down driver choice and implementation once you've decide how much space to allocate for the design. Just a wild guess is a very damped rear wave GRS Slim or even sealed enclosure for the mid+tweeter LA then IB woofer LA implementation Coaxial. That would be neat. The consensus for IB implementation is QTS for the woofer should be around 0.7 or close to it but your crossing over to subs so it might be ok to relax that a bit.
I remember reading some HT theatre literature that the tweeter should be placed very close to the AT screen for best performance. You might want to google that to make sure I'm not lying, its been a while. There were measurements of the HF performance of different distances from the AT screen.
I assume your going full active to make things easier? Maybe a different thread for implementation could be started as IB sealed coaxial is getting a ways away from 3-way full OB LA implementation. We can continue the discussion there so please link the thread. Also more people will comment with ideas as more ideas are always great
. The AVS forum has a lot of stuff for HT implementation but I found it light on full custom LCR like your proposing but there are some good posts for AT screen and speaker placement + room treatment.Cheers!
Mike
Hi Mike did you make the LAIB is a different beast than OB. I've not had the pleasure of listening to an all IB installation. From what I've read there are a lot of advantages to that.
One of the things I like about OB is the lack of impact in the bass in my room when the volume goes up. Some people like that, others don't like it at all. It is a personal presentation/preference choice. Not sure where you sit on that front.
It might be easier to lock down driver choice and implementation once you've decide how much space to allocate for the design. Just a wild guess is a very damped rear wave GRS Slim or even sealed enclosure for the mid+tweeter LA then IB woofer LA implementation Coaxial. That would be neat. The consensus for IB implementation is QTS for the woofer should be around 0.7 or close to it but your crossing over to subs so it might be ok to relax that a bit.
I remember reading some HT theatre literature that the tweeter should be placed very close to the AT screen for best performance. You might want to google that to make sure I'm not lying, its been a while. There were measurements of the HF performance of different distances from the AT screen.
I assume your going full active to make things easier? Maybe a different thread for implementation could be started as IB sealed coaxial is getting a ways away from 3-way full OB LA implementation. We can continue the discussion there so please link the thread. Also more people will comment with ideas as more ideas are always great
Cheers!
Mike
Hi,
Yes. 6, deltalite 2515 for the woofer array and 10 bg neo8-pdr per side. Played with a tweeter array of like 24 pt-mini. Could go either way with tweeter array. Some might like it, but you could get away without out it. It's a subtle change. Xover is 320hz and 9khz.
The ob woofer array is really something. It loads the room differently than a point source ob. Gives the ob presentation buy huge and effortless. I'm really glad I did the project.
