Planar Speaker Asylum

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Planar Speaker Asylum

not quite sure how to read this

68.1.131.10

In Reply to: RE: addendum query - Ashly 2001 posted by Davey on October 24, 2009 at 21:41:23

I appreciate the suggestion and it's certainly reasonable, although I hoped to avoid something like the DCX2496 (not many choices at that price point). I hoped a product like the Ashly might be suitable as a permanent solution, but that depends upon (beyond its build quality, which is an unknown for me) the suitability of its slopes to the architecture of the junior Maggies, but what made that specific choice intriguing is the fact that one can tweak its behavior at the XO frequencies.

The other scary thing about a digital XO is the daunting range of configurations. I think my heart would be content with a little less fiddling than the DCX2496 permits, but I could be wrong. It might be fun to experiment with the myriad permutations such a device affords, but what if I end up back where I started? At least I would have exorcised the demon. Oh what a can of worms this upstream shift has opened!

"Jazz is not dead - it just smells funny" FZ

Follow Ups:

RE: not quite sure how to read this - Davey 07:43:19 10/25/09 (7)
What I mean to say is that a DCX2496 allows to experiment with a variety of configurations easily (and repeatably) for subjective and objective evaluations.

In my view, the DCX2496 is not suitable (un-modified) for a permanent solution in a high resolution system. It's much too veiled sounding relative to an analog counterpart. However, it is a powerful development tool.

Anyways, using a DCX to experiment with various configurations (but keeping in mind what can be realized with a final, analog circuit) is an excellent way to go for Maggie DIY'ers. Your final crossover would be a dedicated, analog, active crossover specifically designed to your application with no extra frills and extra circuitry that a commercial unit like the Ashly would have.

Construction might be a daunting and/or expensive task for the non-DIY'er, but there are fellas like Phil Marchand who can use an existing platform like the XM-44 to achieve whatever might be required.

All that said, you'd be venturing well into "re-designing" one of Magnepan's speaker systems. Some folks are not comfortable with that. :)

Cheers,

Dave.
- but what about the slopes question? - wazoo 09:48:27 10/25/09 (6)
  I understand the utility of the DCX2496 as a design tool, but I also fear that you're correct about its less than stellar sound quality. It has a few features that are very appealing - like the ability to save numerous profiles and call them up on demand. That would permit me to correct mixes to some extent - or, at least, configure them more to my taste. In fact, even if I discover a particular set of points and slopes to be ideal (to my ears), I'd love to preserve level adjustments in the final design.
  The paucity of off the shelf active XO solutions is disappointing in light of the benefits of the line level approach. It looks like only the pro audio products have the degree of configurability that I desire.
  Maybe I should rethink my approach. You know precisely what I'm using right now - I'd like to push the points closer to stock and provide some low end filtering. I actually have a convenient, single-point level adjustment for my subs in the dbx120. So, if I just had the ability to adjust the top end a little (and that would be easy with what I'm using at the present), I'd have my balancing desires met.
  I'm still left with my original question - what about the slopes? In your opinion, is it best to stay in the realm of 6dB/octave slopes? How about assymetrical slopes like those of the initial MMG (I rather liked the passive I built of that design)? How do the steeper slopes work with MMGs? I guess I know your answer. Buy the damn DCX2496 and find out!
  Okay ;- )
  
  "Jazz is not dead - it just smells funny" FZ
  
  Edits: 10/25/09
  - RE: but what about the slopes question? - Davey 08:05:23 10/26/09 (2)
    I can only speak from experience about the MMG's.
    
    In my view, any kind of generic Linkwitz-Riley electrical crossover will yield a too fat mid-range response because of the constant-voltage design. The transducers broad overlap and non-flat response sum to an acoustic response which is not flat when using an electrically "flat" crossover. (I did have some success equalizing it though.)
    
    Thus, the vast majority of commercial units that implement generic slopes and don't allow separate adjustment of high/low turnover frequencies are not suitable.
    
    I don't believe there's much to complain about with the 6db/6db electrical slopes utilized in the latest MMG's. Electrically, this crossover has a broad, deep dip in response, but the acoustic result is beautifully flat in my listening room. I did add a shunt capacitor in the high-pass section to lower its turnover frequency just a bit, but this was a minor change. A line-level version is, of course, better than a passive crossover at speaker level.
    
    Anyways, I don't believe you're going to get significant improvement from your present mid/high crossover setup. However, optimizing your sub/MMG crossover might yield some significant improvements.
    Taking some/all of the bass workload away from the MMG panels yields noticeable improvements. (Even without framing modifications.)
    
    I much prefer dipole woofers to any box solution. My current setup utilizes MMG's with a 80Hz active crossover and woofer equalization mated to "H"-frame dipole woofers using two 10" drivers per side.
    
    IMHO, I don't believe there's an MMG-based system anywhere that sounds better than mine. Terrific for all types of well-recorded music, but only lacks the maximum SPL capability that larger Maggies could provide.
    
    My two cents.
    
    Cheers,
    
    Dave.
    - RE: but what about the slopes question? - mäç 17:31:12 10/26/09 (0)
      > > IMHO, I don't believe there's an MMG-based system anywhere that sounds better than mine.
      
      Including the ones from PG? (lol).
    - okay - wazoo 10:58:48 10/26/09 (0)
      I'll stick with the PLL XO, but, as I mentioned, I want to change the values to approximate behavior which is closer to stock - certain things irritate me with the current values. Currently, I don't have any XO between my subs and the MMGs - that's definitely an issue I want resolved. I've seen a few active devices for sale (such as the NHT X2) that look interesting. I have too much invested in my current subs to change paths, so I'm sticking with my hybrids as they are - I just want to get the XO nailed down.
      
      "Jazz is not dead - it just smells funny" FZ
      
      Edits: 10/26/09
  - RE: but what about the slopes question? - Dawnrazor 15:11:05 10/25/09 (2)
    Dude,
    
    Here is what Andy had to say when I asked the same question.
    
    It starts at the RE 1200hz part
    - http://www.audioasylum.com/forums/MUG/messages/14/145052.htm (Open in New Window)
    - 6dB/octave rules for MMGs - wazoo 11:02:02 10/26/09 (1)
      I cannot argue, and it just seems right to me that it should be so. I'm not so sure about the points, but I think the 1st order slope is proper for these speakers (and the only comments I've received affirm that suspicion).
      
      "Jazz is not dead - it just smells funny" FZ
      
      Edits: 10/26/09
      - RE: 6dB/octave rules for MMGs - Satie 19:15:42 10/27/09 (0)
        
        In Reply to: RE: 6dB/octave rules for MMGs posted by wazoo on October 26, 2009 at 11:02:02
        
        I am all for 6 db slopes.
        
        I am finalizing my mod Tympani PLLXO and the clarity vs. the Marchand 44 LR is significant if not startling.
        
        Removing the speaker level coil I used for a contour circuit for the midrange and integrating it into the PLLXO, now that was startling.
        
        I had everything setup with in phase (electric) crossovers for the Mid/Bass and combined acoustic and electric phase for Tweeter/mid.
        
        I could not apply a first order on the woofer panels because of a rising midrange bump there, so I reverted to a Bessel second order LP in phase with the 1'st order bandpass on the mids.
        
        The challenge turned out to be the matching the tweeter crossover and the preamp (tube) requirement for minimum load impedance while matching volumes with the other amps. Namely because of the lack of very low capacitance caps for my 5-6 khz crossover point (0.003 uF was the lowest I could find at the time), which lowered the required resistance.

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