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Magnepan LRS with two 1x12 OB subs and dspNexus 2/8 DSP control center

216.36.0.64

HAL2010

Setup this system for CAF2024 last weekend in MD in room 702 to demo the dspNexus 2/8 DSP control center for speaker correction and bass management. It was an ABC demo where you could hear the stock original LRS speaker and crossover, then use DSP for speaker on-axis correction and then add two open baffle H-Frame subs with DSP EQ all speakers driven with Orchard Audio Starkrimson Monoblock amps.

Here is the Audiophile Junkies visit to the demo room video:

https://www.youtube.com/watch?v=x3o2Eo-rxUY&t=4s

Better Living Through Audio Nirvana

Follow Ups:

RE: Magnepan LRS with two 1x12 OB subs and dspNexus 2/8 DSP control center - 13th Duke of Wymbourne 17:49:38 11/17/24 (9)
Are the/will the OB subs be a product? If not, can you tell me what drivers you used?
- RE: Magnepan LRS with two 1x12 OB subs and dspNexus 2/8 DSP control center - HAL2010 18:00:35 11/17/24 (8)
  The OB H-Frame subs have installed the GR-Research SW-12-16FR servo subs being used without servo and custom EQ that I developed.
  
  Reference North Audio makes the 1x12 modular flat packs for the OB H-Frames cabinets. They have an automotive finish that I had painted locally.
  
  GR-Research offers servo amp kits with cabinets for their drivers with Rythmik Audio servo amps.
  Better Living Through Audio Nirvana
  - RE: Magnepan LRS with two 1x12 OB subs and dspNexus 2/8 DSP control center - MarcL 10:44:08 11/18/24 (7)
    A couple questions ... how are the GR drivers used without the servo? Are there better choices for a non-servo 12" in an H-frame? I built a 3X recently and tested response with the servo amp and three settings, vs a non-servo amp and I could see a definite difference in the impulse response (I used a miniDSP to get close to the shelf filter). But I didn't do listening tests.
    
    Also ... folks tend to put Norez on the inner surfaces of the H-frame. I couldn't convince myself that the mass of Norez would make a difference relative to a 100lb MDF cabinet. I didn't see any anomalies in an outdoor ground plane measurement ... dead flat ... so can there be audible resonances in an MDF H-frame cabinet?
    
    Thanks!
    Agilist, Musician, Photographer, Audiophile
    Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
    - RE: Magnepan LRS with two 1x12 OB subs and dspNexus 2/8 DSP control center - HAL2010 11:25:25 11/18/24 (6)
      I use the GR-Research drivers with custom EQ on the dspNexus and do not use the sense coils for the demo using original Orchard Audio Starkrimson monoblocks to drive the 1x12's. Since I only use the modular subs they are about 40lb each with the driver. Easier to move than the full 2x12 and higher driver arrays.
      
      The servo amp does two basic things, first is use as a current output amp and second as a servo loop control with the sense coil. There is also a DC servo loop for the current amp. The sense coil needs correction to run the servo loop. I am using EQ to correct the driver in cabinet frequency response with a standard amp, no motional feedback.
      
      There are other drivers for OB that would work in the OB H-Frame. One I have been told about is the Acoustic Elegance OB-12. They are about $600/driver so 2x the SW-12-16FR sub drivers. There are others that would fit the existing cabinet without modifications. They all require EQ to flatten the response for use.
      
      I do not use NoRez in the OB H-Frame modular cabinets I have built from flat packs, so no way to compare before and after.
      
      Any cabinet has resonances under acoustic drive. Instead of a frequency response, a waterfall stored energy plot would be better to see if there is any change in resonances. Should be able to do that with a groundplane measurement and possibly REW. MDF is usually chosen as well damped cabinet material. Subs are high SPL output, so more excitation to show if there is a problem area.
      Better Living Through Audio Nirvana
      - RE: Magnepan LRS with two 1x12 OB subs and dspNexus 2/8 DSP control center - MarcL 13:59:48 11/18/24 (5)
        
        In Reply to: RE: Magnepan LRS with two 1x12 OB subs and dspNexus 2/8 DSP control center posted by HAL2010 on November 18, 2024 at 11:25:25
        
        Thanks!
        
        Agilist, Musician, Photographer, Audiophile
        Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
        
        Thanks too. - 13th Duke of Wymbourne 10:57:30 11/19/24 (4)
        
        In Reply to: RE: Magnepan LRS with two 1x12 OB subs and dspNexus 2/8 DSP control center posted by MarcL on November 18, 2024 at 13:59:48
        
        I have been thinking about making OB 'subs' and equalizing using a miniDSP but what drivers to use? Perhaps the GR drivers are a good choice as they are proven in the application but I already have suitable amps and I can apply the equalization in DSP so I am less interested in the complete GR system. Linkwitz applied equalization to make the total Q of the drivers in the frame to be 0.5, which implies you could use drivers with a range of Qs.
        I suspect the Rythmik amps use the high GR driver Q to push down extension at the cost of transient performance.
        
        Edits: 11/19/24
        
        RE: Thanks too. - MarcL 04:39:05 11/20/24 (0)
        
        In Reply to: RE: Thanks too. posted by 13th Duke of Wymbourne on November 19, 2024 at 10:57:30
        
        Ask ChatGPT:
        
        What factors influence woofer speaker driver design with respect to compliance of the surround material and the choice of cone material, and what is the optimal choice for open baffle dipole woofers?
        
        :-)
        Agilist, Musician, Photographer, Audiophile
        Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
        
        RE: Thanks too. - MarcL 04:32:49 11/20/24 (2)
        
        In Reply to: RE: Thanks too. posted by 13th Duke of Wymbourne on November 19, 2024 at 10:57:30
        
        Fair to say the filtering required for dipole compensation can be done several ways. And it's good to be able to select amplifiers based on their design, power, etc.
        
        But one factor in answering the question of drivers is whether the GR drivers are designed in such a way that they perform best with the servo amp, and can't achieve optimal performance without it. Would a non-servo driver be designed quite differently with regard to material, compliance, damping, excursion? If so, could it perform better overall than the GR servo drivers? Or ... what are the tradeoffs?
        
        Maybe HAL2010 can comment on that.
        Agilist, Musician, Photographer, Audiophile
        Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
        
        RE: Thanks too. - 13th Duke of Wymbourne 17:43:33 11/23/24 (1)
        
        In Reply to: RE: Thanks too. posted by MarcL on November 20, 2024 at 04:32:49
        
        I am not really a speaker guy but that won't stop me from musing...
        Assuming you can get the same frequency response from the closed-loop system as applying equalization to the open-loop system the next thing has to be excursion and distortion. For the same acoustic output and the same cone area the excursions must be the same/very similar. A closed-loop system should have an advantage in overcoming deficiencies in the driver but I don't know how well this one works to reduce distortion. It is monitoring velocity, not displacement and the point of maximum excursion where the cone changes direction produces little/no velocity feedback. So I don't know if it is effective. Someone wiser than me pointed out on this forum years ago that the Rythmik feedback system was developed for sealed subs to overcome the air loading inside the box, which is not a problem for open baffles.
        
        Maybe, then, if you can get the frequency response you want and the excursion you want the rest doesn't matter?
        
        RE: Thanks too. - MarcL 09:16:38 11/24/24 (0)
        
        In Reply to: RE: Thanks too. posted by 13th Duke of Wymbourne on November 23, 2024 at 17:43:33
        
        Good points! I think the most benefit is gained by the open baffle dipole design, and the number of drivers which requires less excursion to move a given amount of air.
        
        Hard to do apples:apples with and without servo because you can't use the same amp and shelf filters. Frequency response is the same. In my tests I saw less distortion with the servo ... albeit under 2% down to 20Hz.
        
        But wow do they sound good!
        
        Agilist, Musician, Photographer, Audiophile
        Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
RE: Magnepan LRS with two 1x12 OB subs and dspNexus 2/8 DSP control center - emailtim 17:44:27 11/16/24 (2)
That is quite the computer monitor !!!
Question, why are there 8 outputs (versus 4) if you are using the stock XOs + 2 subs ?
Are the 4 extra channels for the other speakers in the room ?
TIA

.

2022/03/30 Historical Records CENSORED

Edits: 11/16/24
- RE: Magnepan LRS with two 1x12 OB subs and dspNexus 2/8 DSP control center - HAL2010 19:25:56 11/16/24 (1)
  There are always 8 outputs for a 2/8 configuration and only 4 have XLR connections installed.
  
  That block diagram also has a third pair of speaker outputs for a center channel not in use for the demo.
  Better Living Through Audio Nirvana
  - RE: Magnepan LRS with two 1x12 OB subs and dspNexus 2/8 DSP control center - emailtim 21:47:28 11/18/24 (0)
    Thanks much.
    .
    
    2022/03/30 Historical Records CENSORED
Amazingly simple approach - E-Stat 12:56:50 11/15/24 (0)
the hybrid stat companies don't get.
RE: Magnepan LRS with two 1x12 OB subs and dspNexus 2/8 DSP control center - MarcL 22:12:39 11/14/24 (1)
Nice demo and I enjoyed talking with you guys as always. Alas, I once again missed hearing the OB subs though. Hopefully next time.

Agilist, Musician, Photographer, Audiophile
Magneplanar: 3.7, CCR, MC1,LRS, MMGW, DWM; Outlaw: UltraX12, LFM-1C; Emotiva: XMC-2; Nord: Nord One NC500DM, Nord Three 1ET7040SA; Outlaw: Model 7500; OPPO 205
- RE: Magnepan LRS with two 1x12 OB subs and dspNexus 2/8 DSP control center - HAL2010 02:58:17 11/15/24 (0)
  MarcL,
  Thanks for stopping by the demo room!
  
  Had the open baffle subs running Saturday and Sunday with the LRS.
  
  Tracked the error down to a cabling problem and an easy correction once spotted.
  Better Living Through Audio Nirvana
Very effective demo - Jon L 19:30:55 11/14/24 (8)
and congrats on the latest dspNexus with newest SHARC and AK4499 DAC chips.

The demo is very impressive, but I suspect the majority of (ehem) older gentlemen around here will find the whole measurement/dsp/FIR-IIR/AudioWeaver endeavor rather daunting.

Is there any plans for simpler, easier-to-use solution in the future? I would personally LOVE (and would pay for) something as easy to use as dbx Driverack to measure/dsp/correct but with much better digital and analogue parts!
- RE: Very effective demo - saucyworchester 09:09:07 11/15/24 (0)
  Now don't be ageist Jon. I just rewired my Tardis for cleaner phase reception and clearer chocolate notes upon re-entry.
- RE: Very effective demo - HAL2010 02:51:06 11/15/24 (6)
  Jon L,
  When a customer purchased a dspNexus 2/8 from Hollis Audio Labs, I am bundled with the system to be the crossover designer that works with them to make measurements and then create the DSP crossover processing needed for the system. This includes guiding the customer through Room EQ Wizard measurements for room bass management.
  
  The implementation depends on if you are just doing speaker correction on the existing speaker and crossover or doing a fully active speaker with multiple amps. Integrating subwoofers is part of the system design.
  
  The system has a balance mic input on the front panel to work with a phantom powered measurement mic like a Dayton Audio EMM-6 or Beyerdynamics MM1 with their calibration data with a mic stand and XLR cable to use with REW for the measurements and calculate the correction needed.
  
  That is a bit different than other systems for DSP use, but the results have been improvements for all customers. This includes customers that went the DEQX route before the dspNexus.
  Better Living Through Audio Nirvana
  - RE: Very effective demo - dumpingground 05:52:35 11/15/24 (5)
    Can you share a little more details about the DSP filter crossover design choices you recommend for the customers and the improvements that result? Some of those discussions are briefly discussed in the YT video.
    Specifically,
    With DSP power, one can change the slopes and and crossover points from the OEM 1st order and 2nd order design (at least in a Mag 1.6 parallel crossover). With steeper slopes you can band limit the tweeter to higher frequencies and woofer to lower frequencies more effectively.
    What are some of the considerations for high passing the woofer panel if one has subs in the setup to remove the lower frequencies from the magnepan woofer? lower distortion? What goes into selecting the high pass specific crossover point and slope?
    
    Edits: 11/15/24 11/15/24
    - RE: Very effective demo - HAL2010 12:00:33 11/15/24 (4)
      With Audio Weaver I typically use Linkwitz-Riley or Butterworth crossovers that can be selected as 1st order to 10th order rates. I have been using 8th order L-R for the crossover 2-way or 3-way for multiamp connections. High pass on the woofers for all uses as it removed out of band signals that can cause slapping of the diaphragm when to large to reproduce.
      
      I have been using acoustical or electrical L-R 8th order crossovers to integrate subs to the Magnepan speakers at higher frequencies and using time delay on the mains if the subs are behind them. This removes more LF energy from the planars for lower distortion.
      
      All the amps benefit from direct drive use since they only have to cover a smaller frequency range for each driver. Less stress on the amp and power supplies.
      
      I use REW to measure the responses of the speaker and sub independently and see if there is a frequency that makes sense, but if the response is flat enough, then choose a frequency that is an octave above the speaker rolloff for the crossover point to the sub. The video demo uses that idea for integrating the LRS to the OB subs.
      Better Living Through Audio Nirvana
      - RE: Very effective demo - dumpingground 12:42:25 11/15/24 (3)
        
        In Reply to: RE: Very effective demo posted by HAL2010 on November 15, 2024 at 12:00:33
        
        If you change from the factory OEM crossover slopes to a 8th order L-R, do you still try and keep the same acoustical crossover point? In the case of a Maggie 1.6 which I am most familiar with the acoustical crossover is about 600hz, with OEM crossover slopes of approximately:
        LP LR 12db/oct @ 400hz
        HP BW 6db/oct @ 1475hz
        
        With the ability of a DSP based crossover of 8th order L-R that might become:
        LP LR 48db/oct @500hz
        HP LR 48db/oct @600hz
        
        I can understand the advantage of using DSP based crossover hardware to allow the power amp to directly connect to the panels and to only be responsible for amplifying the pass bandwidth of power that the active crossover passes thru. But I am trying to better understand the benefits of changing from the lower order OEM to higher order DSP crossover slopes.
        
        RE: Very effective demo - HAL2010 13:40:15 11/15/24 (2)
        
        In Reply to: RE: Very effective demo posted by dumpingground on November 15, 2024 at 12:42:25
        
        By using high rate crossovers, the driver frequency overlap is much less and out of band signals to the individual drive foils is lower. Since the 3 drive foils are on one mylar diaphragm, taking excursion out of all foils lowers distortion for the entire planar speaker.
        
        Just correcting the woofer foil output to be at the same output level as the tweeter/supertweeter foils drops the diaphragm excursion.
        
        Crossover points are the same as I am correcting the original speaker with passive crossover installed in this demo. Not a direct drive setup as I did for CAF2023 with the MG10/QR speakers and disconnected the passive crossover to run each drive coil/foil to new 5-way connectors on the plate.
        
        This is a third party on-axis measurement of the LRS speaker model. I do not see that as a flat on-axis response. I used this as the basis for the speaker correction for the LRS at CAF2024 that I then integrated to the two 1x12 OB subs.
        
        Better Living Through Audio Nirvana
        
        RE: Very effective demo - josh358 12:17:22 11/16/24 (1)
        
        In Reply to: RE: Very effective demo posted by HAL2010 on November 15, 2024 at 13:40:15
        
        What distance did he measure it at? The exaggerated bass suggests to me that he measured close up. You cannot do that with dipoles. They must be measured further back, or all you measure is the dipole equalization.
        
        RE: Very effective demo - HAL2010 19:23:10 11/16/24 (0)
        
        In Reply to: RE: Very effective demo posted by josh358 on November 16, 2024 at 12:17:22
        
        The measurement distance was 51in, which is farther than the aperture length.
        Better Living Through Audio Nirvana

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