Ultra nearfield, open-baffle planar system

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  • gbegland
    Senior Member
    • Apr 2005
    • 233

    Ultra nearfield, open-baffle planar system

    After years and years of wanting to acquire a zero gravity recliner, I finally thought to check facebook marketplace. No way I was ever going to spend $2-3K for a new one. Long story short, I scored a perfectly new looking chair for $400. That's more my style!

    As many of you long timers on here may know, over 10 years ago I worked up a rather serious system based on Raal 140-50, BG Neo10 and Rythmik servo subs. To this day, I'm still very happy with the performance, however the living situation has changed dramatically over those 10 years. A new house with much worse opportunity for a good listening space and my "instant family" (fiance and her kids moving in), have basically kept me from fully enjoying this system for quite a while. After finally acquiring the chair for use in my bedroom, I thought, why not create something specifically for use while resting in the chair and reading. I can't do headphones for very long, no matter how comfortable they are. It just drives me nuts, both the pressure and weight on my head AND the lack of correct imaging. I though back to the 2008 RMAF and remembered that there was a personal listening chair on display that year. I could do something similar, but much higher fidelity.

    So, the current plan is to use a spare set of Hypex Fusion FA253 amp/dsp modules, the new Radian LM10n drivers nearly full range, supplimented from 200-300hz down to 80hz or so by an old set of Ascendant Audio Carbon 6.5 I've also got lying around. The plan is to mount the drivers on articulated computer monitor arms from a framework that I'll attach directly to the heavy wood frame of the chair itself. It's the low end that I'd love options and ideas about. I'd like to keep things simple in terms of construction, but willing to think outside the box if anyone has any creative ideas. Ideally something open baffle that could sit just left and right of the armrests of the chair, kind of like coffee tables. Was thinking purely nude drivers, kicked up at an angle to aim directly at me. I could also get lazy and buy the dual 8" Rythmik system, but it's rather spendy to get two of those. They'll likely be within 2-3 feet of my head, so typical considerations for dipole loses and amount of EQ/power needed are greatly reduced. It think if done right, I can get very precise imaging/depth and great dynamics at my position, without too much sound traveling to the rest of the house. The room itself will have minimal effect due to the close proximity and relatively low SPL needed, but as my head will near to the corner, I'll do some acoustical treament just in case.

    I plan to experiment with acoustcal felt "cheeks" for the Radian on the sides and top/bottom, a la the foam pads on the Raal, to create wider dispersion (and hopefully knock down some of the top end peakiness), so as I change positions of the chair I don't have to constantly adjust the aim of the mounting arms. If the Radian's top two octaves are not suitable, I can do a coaxially mounted NOS Neo3 or even smaller spiral ribbon tweeter just feathered in to taste. I'm hoping this felt will also provide some additional loading to the diaphragm as Jon has been experimenting with for the Saint-Saen backchamber.

    Initial top woofer options are Daytona Ref HF series12", SB Acoustics 12″ SB34NRX75-6, or something from AE, but NOT the Dipole series. I had those initially in the my open baffles and found the Qts of nearly 1 to be too high for my liking. AE does have the LO series, but even that kind of seems overkill for the intended operating range. I was actually looking more along the lines of their IBAU or IBHT series. Ultimately, I'm more concerned with clear and tight bass than ultimate extension. Thoughts on any of these options as a place to start? Or got any store bought options that are compact that you've heard that have nice, precise bass? Ideally well below $1,000 each, because at that point, I'll get the Rythmik.

  • technodanvan
    Super Senior Member
    • Nov 2009
    • 1024

    #2
    Interesting project, I'd not heard of Radian before. Looks fun! For reasonably compact bass in the DIY realm I'd really be looking hard at the CSS SDX10 (though it's OOS at CSS right now). If you're ok spending a few more bucks I understand the Seas LROY - both 10" and 8" models now - are really nice and clean (you could get a 10" at a good price from Meniscus right now, it's 30% off). I really don't think a 12" should be necessary when you'll probably be sitting right next to it, but that's just, like, my opinion, man.
    - Danny

    Comment

    • JonMarsh
      Mad Max Moderator
      • Aug 2000
      • 15284

      #3
      It took me a while to find this page...


      The Radian LM10n is a wide band planar ribbon driverwith a recommended operating frequency band150Hz-20kHz. Its flat pattern of straight conductors isevenly distributed over a stretched polymer diaphragmand disposed in a symmetric magnetic structure.As a result, the inductive component of inputimpedance is eliminated a



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      I'd opine that like the GRS PT5010, the optimum operating range is about 400Hz to 2500 Hz, with the right enclosure support.

      Here's the PT5010 in 7.5L with Denim and acousta-stuff, polar to 40 degrees:



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      Fairly easy to develop a good midrange crossover. For ultra near field, which means lower overall SPL, pushing down to 300Hz should be reasonable, maybe even 250Hz.

      the AudioWorx
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      In Development...
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      Resistance is not futile, it is Volts divided by Amperes...
      Just ask Mr. Ohm....

      Comment


      • theSven
        theSven commented
        Editing a comment
        Thanks for finding it!
    • gbegland
      Senior Member
      • Apr 2005
      • 233

      #4
      Originally posted by technodanvan
      Interesting project, I'd not heard of Radian before. Looks fun! For reasonably compact bass in the DIY realm I'd really be looking hard at the CSS SDX10 (though it's OOS at CSS right now). If you're ok spending a few more bucks I understand the Seas LROY - both 10" and 8" models now - are really nice and clean (you could get a 10" at a good price from Meniscus right now, it's 30% off). I really don't think a 12" should be necessary when you'll probably be sitting right next to it, but that's just, like, my opinion, man.
      Radian has been around for decades as an OEM for PA system loudspeakers. Just a few years ago, they hired Igor Levitski to design an updated, improved line of planar drivers after the whole BG/Christie purchase happened and Christie basically pulled the BG drivers off the market. As I understand it, Dai-Ichi, who now owns Radian, was making those original planar drivers FOR BG, currently makes them still for Christie, AND is making this new line of planars as well.

      Those Seas LROY are outrageous! The magnet to basket ratio is off the charts. I'll call Meniscus tomorrow to see if they have any left. As to the 8-10", if I'm doing a sealed box, sure that would certainly be enough, but with the nude dipole consideration, I've got no frame of reference until I prototype something up to hear what I'm getting myself info. You may well be right, but I've got nothing hear right now to even try this idea out.

      Comment

      • gbegland
        Senior Member
        • Apr 2005
        • 233

        #5
        Originally posted by JonMarsh
        It took me a while to find this page...


        Fairly easy to develop a good midrange crossover. For ultra near field, which means lower overall SPL, pushing down to 300Hz should be reasonable, maybe even 250Hz.
        Sorry, I should have linked to the Radian page.

        During development of the original baffles, I tried the dual Neo10 crossed as low as 150hz. My god, did upright bass sing! But at higher levels and with non-acoustic music, they couldn't take it and I ultimately ended up closer to 300hz. I have a sneaky feeling I can get away with 150-200hz with the Radian for this nearfield setup. The idea to use them without tweeters is really driven from having the old Monsoon planar desktop system and listening to Radian's little desktop setup, based in these LM10n, at the ALTI convention in Orlando last month, but time will tell. If I end up needing a helper mid-bass AND add a tweeter, I'll need to re-think the sub situation, since the Hypex is a three way solution.

        A few years ago, I tested all availible planar drivers from PE, the Radian LM8k and all of the NOS BG. The PE drivers were close in many regards, but had the worst low-end performance of the bunch. The Radian had the highest sensitivity of the bunch.

        Adding another photo of further inspiration from a fellow posting over at Audio Science Review. He harvested planar drivers from a set of headphones, added a midbass driver and then built small subs that are over top of his head.

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        Last edited by theSven; 16 July 2023, 21:10 Sunday. Reason: Update image location

        Comment

        • technodanvan
          Super Senior Member
          • Nov 2009
          • 1024

          #6
          That is uh...extremely near field.
          - Danny

          Comment


          • JonMarsh
            JonMarsh commented
            Editing a comment
            No kidding!!
        • theSven
          Master of None
          • Jan 2014
          • 1059

          #7
          Originally posted by gbegland
          After years and years of wanting to acquire a zero gravity recliner, I finally thought to check facebook marketplace. No way I was ever going to spend $2-3K for a new one. Long story short, I scored a perfectly new looking chair for $400. That's more my style!

          I've been a big advocate of zero gravity workstations since 2016. I use it for work, but having one for audio would be very interesting. I had a J-20 workstation and imported it from China as it was cheaper then buying from the US option. That lasted for 7 years and finally the chair wore out and I needed to upgrade.

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          When I decided to upgrade I went with a solution that I could sit or stand as I find there are times I do want to stand. Sitting for 10 to 12 hours a day is brutal on the body! I sold the J-20 to a friend and upgraded to an Ergo Quest workstation 0B. This is a Cadillac compared to a Ford Pinto.

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          Great to see a design on HTGuide for zero gravity chairs! Looking to see how this design progresses and congratulations on getting your chair.
          Painter in training

          Comment

          • theSven
            Master of None
            • Jan 2014
            • 1059

            #8
            Originally posted by gbegland

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            I was looking at this photo closer today and realized those are Really Right Stuff ballheads for a tripod! That is an uber expensive ballhead to use for mounting speakers like that 🤣. Its the monopod head mixed with some other part:

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            gbegland, Do you have the link for where you got that photo? I'm curious to go read through that thread if he says what parts were used to assemble that chair setup.
            Painter in training

            Comment

            • gbegland
              Senior Member
              • Apr 2005
              • 233

              #9
              Originally posted by svenarajala

              I was looking at this photo closer today and realized those are Really Right Stuff ballheads for a tripod! That is an uber expensive ballhead to use for mounting speakers like that 🤣. Its the monopod head mixed with some other part:

              gbegland, Do you have the link for where you got that photo? I'm curious to go read through that thread if he says what parts were used to assemble that chair setup.
              Here you go:

              For about one year my absolute favourite listening setup is an active stereo 3-way (3 separate amplifiers) DIY construction with listening distance of 10-20 cm (depend on the Head position), made from HIFIMAN HE500, Visaton AL-180 for the bass (analogue crossover) and 2 x Dayton Epique E180 via...


              Comment


              • theSven
                theSven commented
                Editing a comment
                Thank you
            • gbegland
              Senior Member
              • Apr 2005
              • 233

              #10
              Just a little update. All parts for V1 are here now. Woofer went in a different direction, but only becuase I got a deal I could not refuse. Measurements and listening tests will determine if they stay or I go to V2.

              Look at the comparison of a standard Neo3 next to the little Radian LT2. I think it looks like a nice combination for an all planar coaxial unit. As far as the woofer, it's a JBL Arena 12. Not your typical car audio woofer that's all show and no go. Features dual differential drive just like the higher end pro woofers and a rather light cone for this type of driver.​

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              Last edited by theSven; 14 November 2023, 22:05 Tuesday. Reason: Put photos inline with post

              Comment


              • JonMarsh
                JonMarsh commented
                Editing a comment
                I'll be very curious to see how the drivers work out...
            • theSven
              Master of None
              • Jan 2014
              • 1059

              #11
              Build thread?? I'm looking forward to seeing this design built out as well.
              Painter in training

              Comment


              • gbegland
                gbegland commented
                Editing a comment
                Probably. Final version might take a while, as I've got too many home improvement projects going on simultaneously. But I'll at least mock something up soon to test the entire proof of concept and most importantly this particular subwoofer.
            • gbegland
              Senior Member
              • Apr 2005
              • 233

              #12
              Well. that's unfortunate. I just noticed that Radian is up to a MK2 version of the LT2 now. Of course, it's not shown on their own website, but that's been a hot mess for years. US Speaker has them listed though. It's got the more durable, better looking chassis that now matchs the rest of the line of planars. I wish I had known about this earlier.

              Radian LT2.2 is a high frequency Planar Ribbon driver. The Radian LT2.2 is for speaker tweeter replacement or upgrade. Radian LT2.2 features a Planar Ribbon. The Radian LT2.2 is available here. Repair your old speaker systems with Radian speaker parts.


              Looking at the tests from Vance, I expect the X-over starting point BTW LM10n and LT2 will be no lower than 3KHz ballpark. And steep too.

              For this Test Bench, Vance Dickason characterized the LT2 Ribbon Transducer and corresponding waveguide from Radian Audio Engineering. This is effectively a smaller version of the LT6 ribbon transducer reviewed in the July 2020 issue of Voice Coil, but offering much more diverse possibilities, as Vance Dickason discovers. And as the compact LT2 shows, this was designed to be more of a hi-fi or home theater substitute for any high frequency driver. This article was originally published in Voice Coil, August 2020.

              Comment

              • tktran
                Senior Member
                • Jan 2005
                • 661

                #13
                That JBL woofer costs serious $$$ (MSRP $500). I actually wonder whether most of the R&D is in automotive audio... because those customers are happy to spend big bucks.

                Some years ago Data-bass.com tested a heap of 12" + subwoofers, and the TOTL models from the likes of Rockford Fosgate, etc had advanced technology than many home audio subs did not.

                Can you share a free air impedance sweep of that Arena 12?

                Comment

                • gbegland
                  Senior Member
                  • Apr 2005
                  • 233

                  #14
                  Yeah, retail pricing on those is a no go for sure. I got both for about half price of a single driver.

                  Comment

                  • tktran
                    Senior Member
                    • Jan 2005
                    • 661

                    #15
                    Oh that’s just teasing us Greg!

                    Please post an impedance sweep when you are able…

                    Comment

                    • gbegland
                      Senior Member
                      • Apr 2005
                      • 233

                      #16
                      Finally getting back to working on this project. Click image for larger version

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                      • Winter
                        Member
                        • Nov 2007
                        • 81

                        #17
                        A test review of the Radian LM10n planar midrange written by Vance Dickason appears in the January 2024 edition of Voice Coil Magazine.

                        Comment

                        • gbegland
                          Senior Member
                          • Apr 2005
                          • 233

                          #18
                          Originally posted by Winter
                          A test review of the Radian LM10n planar midrange written by Vance Dickason appears in the January 2024 edition of Voice Coil Magazine.
                          Yes, I had seen that this was in the latest issue, but I no longer have a subscription, so can't have a peak at the results.

                          Comment

                          • gbegland
                            Senior Member
                            • Apr 2005
                            • 233

                            #19
                            We've got sound. Proof of concept for signal flow and channel to driver wiring. No measurements yet, but some basic settings in the Hypex DSP based on manufacturer plots. That's the good news. The bad news is that the Adam Audio Sub 7's I ordered on a screaming clearance sale were both bad. One was completely DOA and the other had self noise even with no source plugged in. Not too sad, as I expected they would not be very good, but for the price, I thought they'd be good for some experimentation. Back to the JBL drivers for the low end.Click image for larger version  Name:	PXL_20240121_210607067.jpg Views:	0 Size:	2.72 MB ID:	950661

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                            • gbegland
                              Senior Member
                              • Apr 2005
                              • 233

                              #20
                              New LT2.2 tweeters arrived with what are supossed to be the matching waveguides. Unfortuantely, they do not actually fit the new tweeter, which got wider as compared to LT2. The LT2 DOES fit into the recess, as expected. Radian has been contacted with the mistake, so we'll see what they have to say about it. I was hoping these would both improve the top end response, and allow me to have a simple place to attach some sort of a bridge to hold it to the LM10n. I'm sure the naked tweeter would have had some diffraction issues and I hope the smooth, curved profile of the waveguide will impove this. Construction quality of the 2.2 has certainly improved and as such, is now in line with the construction methods of the larger drivers. No more glue joints or rivets.

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                              • technodanvan
                                Super Senior Member
                                • Nov 2009
                                • 1024

                                #21
                                The waveguide seems like a nice idea, but it sure covers up a lot of the mid! Any concerns on that front?
                                - Danny

                                Comment

                                • gbegland
                                  Senior Member
                                  • Apr 2005
                                  • 233

                                  #22
                                  Originally posted by technodanvan
                                  The waveguide seems like a nice idea, but it sure covers up a lot of the mid! Any concerns on that front?
                                  For sure. The rear could be covered with acoustic felt and/or holes could be drilled out of the waveguide.....or both.

                                  Comment

                                  • gbegland
                                    Senior Member
                                    • Apr 2005
                                    • 233

                                    #23
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                                    So many options. If the felt works out, perhaps I can skip the separate tweeter altogether. Simplification would be nice, but we'll see where this all leads eventually. I don't want to box myself into any specific solution just yet. Only enough time to play with parts today. Still no serious listening or maesurements.
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