Planar Speaker Asylum

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Planar Speaker Asylum

RE: Let's make it simpler, then.

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In Reply to: RE: Let's make it simpler, then. posted by JBen on August 12, 2010 at 07:13:26

Yeah, the tweet scares me too.

I think though if you go through a crossover you should be ok using a small battery.

No one here remembers the bending of our minds

Follow Ups:

RE: Let's make it simpler, then. - DrChaos 10:11:23 08/12/10 (10)
How much DC will go to a tweeter behind a crossover's cap? Just about zero, right?
why not put a 10-20 ohm resistor in series with the battery?
The fuses are what, around 3 amps? If the tweet is 3 ohms and you put a 9V battery, you'll be at the design limits.
Seems if you use a 1.5 V battery and any additional resistance you'll be well under the limit.
Don't bypass the fuse for this test! You need it now to prevent boneheads.

Edits: 08/12/10
- RE: Let's make it simpler, then. - JBen 11:24:38 08/12/10 (9)
  Thanks; worry not, I'll figure it out. I have done it with the bass panel, just not the tweeter.
  
  As for realistic measuring and flatness, I summarized the conditions right over the readings but forgot to add that this is a 1/6 octave smoothing graph. Using the typical 1/3 octave smoothing, things look way too smooth! It may be the way that the lastest version of REW scales the charts but 1/3 octave does not portray enough of what I hear.
  
  I do use a calibrated mic and typically place it aiming at the center between the MMGs, right were my ears are. Along the 2 years I have been tweaking things, the response has increasingly become more uniform. I can elaborate, if you have questions.
  
  Do keep in mind that, normally, I bi-amp. These readings were taken in the process of testing the Razoring tweaks under varied conditions. In this case, a normal speaker-level xover.
  
  The question in my mind now is if what "I thought" was the same polarity, is not in fact, inverted. The original wiring is long gone. I could be wrong about the polarity.
  
  Intuitively, for the values used, I have a hard time conceiving that the center cancellations can happen with other than inverted polarity. But, such are the vagaries of phase shifts, that I'd rather question myself. After all, it appears that 2 different simulation systems (Davey's and Dawnrazor's) say that I have it wrong. If I am, I'd be the first to admit it.
  - More info - Dawnrazor 20:27:55 08/12/10 (5)
    Hey J,
    
    Check out this schematic from the archives. I shows the latest mmg crossover and the drivers are clearly have swapped polarity.
    
    Where are Davey or Neo or Hem or Andy when you need them?
    
    No one here remembers the bending of our minds
    - http://www.integracoustics.com/MUG/MUG/tweaks/tazmon/MMG_22j (Open in New Window)
    - Tested the tweeter - Dawnrazor 21:05:17 08/12/10 (4)
      with a AA battery through the crossover.
      
      No harm, but good fning luck seeing any movement! I couldnt feel any either.
      
      I think it is safe to assume that the panel drivers are consistent meaning if the left most trace of the tweeter is + then so is the left most trace of the woofer. Just keep in mind the mirror image.
      
      No one here remembers the bending of our minds
      - RE: Tested the tweeter - JBen 09:42:34 08/13/10 (3)
        
        In Reply to: RE: Tested the tweeter posted by Dawnrazor on August 12, 2010 at 21:05:17
        
        Lunch break quickie.
        
        D, I had visitors last evening so I never got to first base on checking. A few minutes ago, I looked at the current xover diag (factory) in the MUG. At first glance, not remembering what I have at home, I'd say that they do invert and so am I, unknowingly.
        
        I am scratching my head on a couple of things. It may be that the plate connector for newer MMGs is marked different from what came with ours. In my plate, though I don't really use it, I remember that the "+" is at the opposite side of where the fuse is.
        
        This diagram, showing only the back of the connector seems to suggest that the polarities are marked different in the new ones. Hard to believe they'd go to the expense, though. So, it may be that I am getting drunk on just a Ham & Cheese + Coke lunch.
        
        More - Dawnrazor 19:47:08 08/13/10 (2)
        
        In Reply to: RE: Tested the tweeter posted by JBen on August 13, 2010 at 09:42:34
        
        Hey J,
        
        You are getting old man. A lunch quickie used to be something more than a ham/cheese and a coke!
        
        I am scratching my head on a couple of things. It may be that the plate connector for newer MMGs is marked different from what came with ours. In my plate, though I don't really use it, I remember that the "+" is at the opposite side of where the fuse is.
        
        I pulled out my original plate from the closet. You have an excellent memory. But look at the schematics. The fuse is on the NEGATIVE lead.
        
        In the magnepan schematic they show the BACK of the plate so the positive lead is on the right.
        
        In the 2nd one, it shows the fuse on the negative lead.
        
        http://www.integracoustics.com/MUG/MUG/tweaks/MMG%20XO%20Diag.gif
        http://www.integracoustics.com/MUG/MUG/tweaks/tazmon/MMG_22jun99.gif
        
        So it appears to me that the fuse is indeed on the negative leg, and that is why is it far from the + lead. And that magnepan made no changes in the plates though I have not seen a new mmg, though I thing you are right in that they wouldnt change the way the plate is made.
        
        No one here remembers the bending of our minds
        
        I called them the wrong names - factory polarity is inverted for MMG panels - JBen 21:26:19 08/13/10 (1)
        
        In Reply to: RE: More posted by Dawnrazor on August 13, 2010 at 19:47:08
        
        I just finished the battery test. Every damn D & C battery in this house, 10 in series, could not force the tweeter to visibly move. The mid/bass can be observed (slightly) with just 5. Then, I remembered the cordless tool batteries. Bingo! A 18v drill bat, placed on the tweeter, did enough that I was able to see the mid/bass section next to it move. It moves in the opposite direction.
        
        Indeed, I had the names wrong. I was using the correct & proper polarity between drivers but calling them the opposite of what they really are. The factory setup is to have the panel polarity inverted. That is what the blue line in the chart really represents. That is the reason why it is flatter.
        
        Tracing back to the xover boxes, revealed a cable segment set that was inverted there. Theses boxes are not the normal ones used for bi-amp. I dusted them off for the Razoring tests. So, I must have had this in error for a while. The habit of making a frequency scan after setup changes hid the truth from me after the system achieved a "predictable sound". If a scan showed a non-linear response and it was fixed by inverting, that was usually "it", as long as the expected sound balance & imaging returned. Along the way, I lost track of the proper name for "it".
        
        Bummer, I've gotta check and revise descriptions in some of those scans of speaker-level xovers that survived the hard drive crash. Also, I have to edit postings where this type of polarity may have been mentioned ...starting with the chart above.
        
        My apologies to all who may have been mislead by my stupid oversight.
        
        BTW, D, the plate thing only called my attention because -- assuming all MMGs have that same plate -- the speaker wiring shown is at odds with the schematics shown below it. See, the Blue wire on the schematics comes from the (-). Yet, the Blue wire on the speaker wiring comes from the (+) location (at least, where the (+) is in my plates).
        
        Y'r right about the quickie, D! :-))
        
        RE: I called them the wrong names - factory polarity is inverted for MMG panels - pictureguy 22:59:31 08/13/10 (0)
        
        In Reply to: RE: I called them the wrong names - factory polarity is inverted for MMG panels posted by JBen on August 13, 2010 at 21:26:19
        
        I am glad you chased it down to 'root cause' and have fixed it.
        Now you are back on track...
        Excellent work.......
        Too much is never enough
  - RE: Let's make it simpler, then. - DrChaos 11:53:30 08/12/10 (1)
    Specifically, how does the software measure the frequency response?
    
    Is it direct (short-time, quasi anechoic) response or steady-state averaged response?
    - RE: Let's make it simpler, then. - JBen 13:48:29 08/12/10 (0)
      From REW's site: Frequency response measured using logarithmically swept sine signals ...with approx 0.36Hz resolution across the measured range or via real time analyzer with up to 1/48th octave resolution.
      
      Separately, I have used other means that yield similar results with regard to frequency response. BTW, I trust you know that FR is only part of the picture...more so with our Maggies. Yet, it is a good base indication.
  - RE: Let's make it simpler, then. - pictureguy 11:37:45 08/12/10 (0)
    depending on crossover 'orders', the cancelation can occur with drivers IN or OUT of phase (electrical).
    
    Each crossover order in ascending order shifts the phase an additional 90 degrees.
    Too much is never enough

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