Planar Speaker Asylum

Welcome! Need support, you got it. Or share your ideas and experiences.

Planar Speaker Asylum

MG-1.7 crossover

83.226.135.220

Any information on the crossover? Is it a two-way speaker with a filler driver* like the MG-2.7?

*BeO used this in the seventies.
Roger Gustavsson

Follow Ups:

RE: MG-1.7 crossover - Peter Gunn 15:27:38 07/24/10 (6)
It's 3 drivers (barely) but it's not a 3 way, in fact it's very close to my design on the 3 series which would make it a "two and a half way". Otherwise it's a 6dB 1st order XO.

It is rather confusing stock however. As soon as I can make an understandable image I'll post it and a report (hopefully this week).

It's all about the music...
- RE: MG-1.7 crossover - Davey 09:08:23 07/26/10 (0)
  'Think you might want to check with Magnepan before posting a schematic of one of their speaker designs? (At least as a courtesy.)
  
  Dave.
- RE: MG-1.7 crossover - roger.barbara@bredband.net 02:31:30 07/25/10 (0)
  Great PG!
  
  Roger Gustavsson
- RE: MG-1.7 crossover - Davey 19:54:46 07/24/10 (3)
  For Roger....the 2.7 is not a "filler driver" system similar to the B&O approach. That system design targeted a two-way, second-order generic response, but the two drivers were connected with the same polarity. This would yield a huge dip at the crossover frequency. Enter the "filler driver" which was designed with first-order acoustic slopes at the same cutoff frequencies which, in theory, perfectly filled in the notch. In this way all drivers were connected with the same polarity and the system yielded theoretically perfect phase response. "Transient Perfect" is a label you might see applied.
  The 2.7 crossover doesn't satisfy any of the requirements for the "filler driver" concept.
  The electrical response chart posted by Neolith looks exactly correct. It matches my own perfectly.
  Hope that helps.
  Cheers,
  Dave.
  
  Edits: 07/24/10 07/24/10
  - I think PG's talking about the 1.7 crossover (being 2 1/2-way), Davey? nt - andyr 19:59:17 07/24/10 (2)
    .
    - Yes indeed. My mistake. - Davey 20:03:31 07/24/10 (1)
      Thank you.
      
      Dave.
      - No probs. :-)) nt - andyr 20:23:25 07/24/10 (0)
        
        In Reply to: RE: Yes indeed. My mistake. posted by Davey on July 24, 2010 at 20:03:31
        
        .
RE: MG-1.7 crossover - gregmacknass2@netzero.com 07:27:12 07/24/10 (7)
The 2.7 is a 3 way speaker
- RE: MG-1.7 crossover - roger.barbara@bredband.net 08:13:14 07/24/10 (6)
  Yes, I know that Magnepan say so. The midrange of the 2.7 is very limited, just filling in below the tweeter. The mid is far from the mid of the MG-III, MG-3.3, MG-3.5 or MG-3.6. Is the mid of the 2.7 just a part of the bass driver or is it separated by some clamping of the Mylar sheet?
  
  And what does the 1.7 look like under the sock?
  Roger Gustavsson
  - RE: MG-2.7 crossover - neolith 15:43:52 07/24/10 (5)
    Here's a Bode plot of the 2.7 xo
    �
    
    I plan to procrastinate my demise for as long as possible. In the meantime, I practice by putting off all the little stuff.
    - RE: MG-2.7 crossover - Davey 20:34:48 07/24/10 (4)
      Interesting electrical crossover response isn't it? :)
      
      Dave.
      - RE: MG-2.7 crossover - neolith 07:14:35 07/25/10 (1)
        
        In Reply to: RE: MG-2.7 crossover posted by Davey on July 24, 2010 at 20:34:48
        
        Certainly is. It would be nice to see the actual acoustic response with and without the tweeter or mid-driver to see what Magnepan was trying to accomplish.
        BTW, too bad that chain came off; it would have been a virtual tie going in to Paris.
        �
        
        I plan to procrastinate my demise for as long as possible. In the meantime, I practice by putting off all the little stuff.
        
        RE: MG-2.7 crossover - Davey 08:07:48 07/25/10 (0)
        
        In Reply to: RE: MG-2.7 crossover posted by neolith on July 25, 2010 at 07:14:35
        
        I'm of two minds about the chain incident. But, water under the bridge.
        
        My favorite guy in the Tour has always been Robbie McEwen. Wheelying across the line in the mist at the Tourmalet......Classic. :)
        
        Dave.
      - RE: MG-2.7 crossover - andyr 20:59:13 07/24/10 (1)
        
        In Reply to: RE: MG-2.7 crossover posted by Davey on July 24, 2010 at 20:34:48
        
        There's not much spacing between the mid HP -3dB point and the mid LP -3dB point ... I thought "well-behaved" bandpasses should have about 2 octaves separating the -3dB points?
        
        I would think it would sound better if you moved the "crossover frequency" between mid and QR tweeter from where it is (about 1,900Hz) to 2,900Hz or more. And use a res to reduce the level of the tweeter by a couple of dB.
        
        IMO, the big impedance spike at about 550Hz is a problem too. I have found from playing with lspCAD that flattening the overall electrical frequency response reduces the stock impedance spike. :-))
        
        Regards,
        
        Andy
        
        RE: MG-2.7 crossover - Davey 21:17:31 07/24/10 (0)
        
        In Reply to: RE: MG-2.7 crossover posted by andyr on July 24, 2010 at 20:59:13
        
        As I always say.....since the acoustic responses are missing it's difficult to determine anything meaningful about the overall response of the system based on just the electrical slopes. :)
        
        I don't think the impedance peak is too bad. It's only about 10 ohms. Heck, a stock 1.6 crossover "spikes" all the way to 20 ohms.
        
        Much depends upon the amplifier output impedance in determining whether these types of impedance variations are concerning.
        
        Cheers,
        
        Dave.

Post a Followup:

FAQ

Post a Message!

Forgot Password?

Moniker (Username):
Password (Optional):
	Remember my Moniker & Password (What's this?) Eat Me
E-Mail (Optional):
Subject:

Message:	(Posts are subject to Content Rules)

Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:	Automagically notify you when someone responds.

To view your new posting or follow-up, click on the RELOAD or REFRESH button on your browser.

This post is made possible by the generous support of people like you and our sponsors:

Kimber Kable