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Maggie MG-20 crossover questions

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Greetings,

First time post here: I recently acquired a pair of Magnepan MG-20s (1999) with new ribbon tweeters. It's currently running bi-amped with a Marchand XM26 active crossover. Do these speakers NEED an external crossover, or can they safely be used with a single amplifier and the stock built-in crossover? Am I correct in assuming the built-in unit is in fact a passive crossover, rather than just wired terminals? If it is a crossover, wouldn't that mean I'm essentially running the signal through two crossovers? That would seem counterproductive.
Finally, is anyone else running an MG-20/XM26 combo that can advise on the best crossover frequency?

Follow Ups:

RE: Maggie MG-20 crossover questions - neolith 18:38:01 12/08/21 (3)
The external OEM crossover for the MG-20 is 3rd order LP at 133 Hz with a 1st order HP at 310 Hz, so a good approximation is 130 (or even 150) and 300 Hz. You will have to open up the unit to see what modules are present. Marchand will have labeled the modules with the frequency and order (6, 12, 18 or 24 dB). If the modules are different, you can order what you need from Marchand. FWIW, if the modules are 24db I would recommend changing them as it has been my experience that the L-R XO is not Maggie friendly.

"Our head is round in order to allow our thougths to change direction." Francis Picabia
- RE: Maggie MG-20 crossover questions - Soundbiter 20:23:17 12/08/21 (2)
  This is all good info, thanks guys. I'll have to learn about 1st-order, third-order, etc., this level of technical crossover info is all new to me.
  Neolith, I looked inside the XM26...the high-pass cards are 300Hz 6dB, and the low pass cards are 100Hz 12dB. Would you recommend trying the 150 low pass card? I find the bass kinda 'boomy'; it's present, but not as detailed as I would like. Maybe that's in part the room; which is 23' x 24', vaulted ceiling, carpeted, and a fairly open back wall behind the listening area. I've got the high-pass volume pots backed off about 50-60 degrees less than the low-pass pots (which are at full volume). What I find odd is that while listening standing up I can hear some 'air' and bloom, which I love, but that becomes lost at sitting height.
  Just today a Bryston 10b-Std active crossover presented itself available. Would that give the MG-20s more flexibility and better fidelity?
  - RE: Maggie MG-20 crossover questions - neolith 08:28:47 12/09/21 (1)
    I would leave the modules alone for the time being. What needs to be adjusted is the gain. The goal is to have both amplifiers producing the same gain. So if the bass amp has a gain of 28 dB and the treble is 24 dB, you need to compensate by adding 4 dB to the treble (or reduce the bass by 2 dB and increase the treble by 2 dB - you get the idea). The sensitivity of the amplifier is not the same as gain and sometimes the manufacturer will list the sensitivity but not the gain. To convert sensitivity to gain:
    gain = 20*log(sqrt(8*Max Watt)/sens)) Note: Sensitivity is the input voltage that produces the rated wattage with an 8 ohm load.
    
    "Our head is round in order to allow our thougths to change direction." Francis Picabia
    - RE: Maggie MG-20 crossover questions - Soundbiter 09:16:46 12/10/21 (0)
      Neolith,
      Thanks for the info on gain. I think I'm okay on that. All amps downstream from the Marchand are the same brand (McIntosh solid-state), though there's a 26 year age difference between them. With all Marchand pots at full gain, the low/high freq. mix is pretty well balanced. For my personal taste (depending on genre or song), I like fairly strong bass, though of course nothing like Rap levels, so I backed off the high-pass to get the balance that seems to work for the room and my ears.
RE: Marchand XM26 ... - andyr 23:50:11 12/05/21 (1)
Very nice! :-))

What XO config is it set up for?

Andy
- RE: Marchand XM26 ... - Roger Gustavsson 00:07:10 12/06/21 (0)
  The external crossover for the MG-20 looks like this:
RE: Maggie MG-20 crossover questions - grantv 17:35:29 12/05/21 (7)
There are 2 xovers from the factory.
Internal is midrange to tweeters.
External is mid to bass.
Unless surgery has been done by a PO, the active xover simply replaced the Magnepan external unit. Did you receive any xover boxes?
- RE: Maggie MG-20 crossover questions - Soundbiter 18:32:14 12/05/21 (5)
  Grant,
  The Marchand XM26 came with this pair (they came with Mye stands, too), but the factory external crossover did not come with them. So are you saying that the factory external crossover was a requirement, rather than an upgrade option?
  - RE: Maggie MG-20 crossover questions - Green Lantern 05:30:30 12/06/21 (0)
    Grants 100% correct, I have the MG20's but they did not come with the factory XO so I had Phil build one for me (XM44 two-way). Took a while but I was overseas so it didn't matter. Cost me $1500 in 2010 but they're around $2K now I see.
    He threw in a bunch of different modules (cards) to play around with but I haven't gotten around to them.
    
    Edits: 12/06/21
  - RE: Maggie MG-20 crossover questions - grantv 20:09:47 12/05/21 (2)
    As Tim said, you need one or the other.
    One stereo amp and the Magnepan passive xover, or 4 channels (a 4 channel amp or 2 stereo amps) with (usually) an electronic xover ahead of the amps.
    There are other options, including making your own passive mid-bass xover.
    Honestly, bi-amping is a great improvement if you can swing another amp. If not identical as existing, you'll have to horizontally bi-amp.
    Nice on the Mye Sound stands inclusion. ;)
    
    Edits: 12/05/21
    - RE: Maggie MG-20 crossover questions - Soundbiter 21:32:37 12/05/21 (1)
      Okay, great to know this! I missed Tim's informative post (operator error on my part, new to the site), but now I've read it and see the schematic he attached also. I do have the XM26 horizontally bi-amped with non-identical amps. Thank you both for the info!
      Steven
      - RE: Maggie MG-20 crossover questions - emailtim 11:48:27 12/06/21 (0)
        
        In Reply to: RE: Maggie MG-20 crossover questions posted by Soundbiter on December 05, 2021 at 21:32:37
        
        Your XM26 is a much more versatile option than the passive XO.
  - RE: Maggie MG-20 crossover questions - emailtim 19:00:44 12/05/21 (0)
    Here is the 20.0 XO posted on the MUG. The part in the dotted line is the mandatory external XO which prevents low frequencies from going to the mids and tweets.
    You need either the Marchand XM26 (or equivalent) or the passive XO to protect the mids and tweets/ribbons from the bass and sub frequencies.
    
    Edits: 12/05/21 12/05/21 12/06/21
- P.S. and P.P.S. - grantv 17:38:34 12/05/21 (0)
  Welcome aboard!
  The external xover would look something like this.

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