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RE: "Anyone here seen a .7 crossover schematic yet" ...

120.146.97.173

In Reply to: RE: Biwire binding post on mg1.6 versus 1.7i posted by ABliss on November 24, 2021 at 13:39:54

If you want to bi-amp your .7s then you don't really need to know what the actual XO component values are ... bcoz you already know that it:
* is 1st order - so has 6dB slopes
* and is a series XO.
So if you used, say, a miniDSP 2x4HD ... you could set up 6dB BW HP & LP slopes and change the XO frequency on the fly between 700Hz and 1200Hz - and decide which frequ value you preferred. (This range of frequencies covers all the 2-way Maggies.)
Andy
PS: Obviously, you need to bypass the stock passive XO to do this. And install a 2nd pair of spkr-wire connectors.

Edits: 11/25/21

Follow Ups:

RE: "Anyone here seen a .7 crossover schematic yet" ... - Davey 07:59:40 11/25/21 (37)
You DO need to know what the component values are because the crossovers are setup with different filter points for low-pass and high-pass. (This is especially true of the older models with parallel crossovers.)
And, a confirmation measurement of the impedance of the xducers should be incorporated as well.
You can't just select a single crossover frequency for both portions and vary it. You'd end up with a hugely bumped up midrange response.
Dave.

Edits: 11/25/21
- The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. - GreatSound 19:51:34 11/26/21 (14)
  Giving a optimally flat bass response..
  
  Edits: 11/26/21 11/26/21
  - RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. - Davey 21:02:35 11/26/21 (13)
    Which older Magnepans are you talking about????
    
    Dave.
    - RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. - GreatSound 10:34:29 11/27/21 (12)
      The older three series before the 3.7.
      - RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. - Davey 12:35:03 11/27/21 (11)
        
        In Reply to: RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. posted by GreatSound on November 27, 2021 at 10:34:29
        
        Well, it's debatable whether those are Butterworth acoustic alignments.
        
        Regardless, only Butterworth alignments of first-order sum to a flat response. All others have a hump of approximately 3db at the crossover frequency. Those older Maggie models are definitely not first-order.
        
        Dave.
        
        RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. - GreatSound 17:18:49 11/28/21 (10)
        
        In Reply to: RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. posted by Davey on November 27, 2021 at 12:35:03
        
        ' Regardless, only Butterworth alignments of first-order sum to a flat response.'
        All buterworth filters have the flattest response in the band pass vs other alignments.
        You are a novice that does not understand filters and crossovers.
        
        Edits: 11/28/21
        
        RE: I noticed you made a response to my post ... - andyr 23:57:31 12/03/21 (0)
        
        In Reply to: RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. posted by GreatSound on November 28, 2021 at 17:18:49
        
        and then deleted it, GS.
        
        You really need to get a hold of yourself. :-((
        
        Andy
        
        "... You are a novice that does not understand filters and crossovers. ..." - emailtim 15:13:31 12/01/21 (0)
        
        In Reply to: RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. posted by GreatSound on November 28, 2021 at 17:18:49
        
        You stepped in it knee deep with that uninformed comment.
        
        Sorry - Dave is the last person on this site that you could call "a novice"! :-)) nt - andyr 17:41:54 11/30/21 (0)
        
        In Reply to: RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. posted by GreatSound on November 28, 2021 at 17:18:49
        
        .
        
        RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. - Davey 18:09:00 11/28/21 (6)
        
        In Reply to: RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. posted by GreatSound on November 28, 2021 at 17:18:49
        
        No, I'm afraid not. :) Butterworth filter sections are maximally flat, but not the crossover alignments. Linkwitz-Riley, among others, sum to a perfectly flat amplitude response.
        'Better break out the textbooks on various filter alignments and get yourself up to speed.
        This is a page I've contributed to a few times over the years and it's pretty well sorted out now.....as Wikipedia pages go. Start with that and that'll get you back on track.
        Dave.
        https://en.wikipedia.org/wiki/Audio_crossover
        Audio crossover (Open in New Window)
        
        Edits: 11/28/21 11/28/21
        
        RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. - GreatSound 18:13:54 12/03/21 (5)
        
        In Reply to: RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. posted by Davey on November 28, 2021 at 18:09:00
        
        The MGIIIa manual suggests a butterworth alignment for the bass section when using an active crossover.
        There really is not a completely butterworth crossover, used in audio.
        
        Edits: 12/03/21 12/03/21 12/03/21
        
        RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. - Davey 19:29:56 12/03/21 (4)
        
        In Reply to: RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. posted by GreatSound on December 03, 2021 at 18:13:54
        
        You're tap dancing backwards now. As I said earlier, "it's debatable whether those are Butterworth acoustic alignments."
        I'm well aware of how these crossovers work and how to construct active equivalents or variations of them.
        
        Here's an example of 3.6 prototypes I built (still in use BTW)....and contributed to this forum over twenty years ago. :)
        http://www.integracoustics.com/MUG/MUG/tweaks/davey/mg3.6xo.htm
        
        Next time you comment on my posts, have your shit together.
        
        Dave.
        
        RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. - GreatSound 20:42:36 12/03/21 (3)
        
        In Reply to: RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. posted by Davey on December 03, 2021 at 19:29:56
        
        It is debatable whether your solution is better than the stock crossover!
        
        RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. - Davey 20:59:38 12/03/21 (2)
        
        In Reply to: RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. posted by GreatSound on December 03, 2021 at 20:42:36
        
        My solution IS the stock crossover. Curves are identical.
        Did you even read the page?????
        
        And, it's only one, possible, solution. I'm not saying it's the best solution. Line-level crossovers allow much more versatility in implementation and other improvements.
        
        Dave.
        
        RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. - GreatSound 12:54:52 12/11/21 (1)
        
        In Reply to: RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. posted by Davey on December 03, 2021 at 20:59:38
        
        "stock" is the same and not a solution to a non existent problem!
        
        A crossover design is more than "curves".
        
        What makes your solution better?
        
        RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. - Davey 18:10:49 12/11/21 (0)
        
        In Reply to: RE: The older Magnepans also used a butterworth alignment for the mid to bass portion of the crossover. posted by GreatSound on December 11, 2021 at 12:54:52
        
        Maybe one of the other fellas can school you on the basic concept.
        You have all the appearances of a troll. I can't be bothered further.
        
        Dave.
- RE: I agree with you, Dave but ... - andyr 12:09:20 11/25/21 (21)
  nowhere did I say that the HP & LP frequencies had to be the same.
  
  And if you are using an active XO setup ... the driver impedances are irrelevant.
  
  Andy
  - RE: I agree with you, Dave but ... - Davey 17:00:44 11/25/21 (20)
    You didn't say either way, but it's important to clarify items like this because it can confuse the inexperienced.
    
    Regardless, the inherent linking of the networks is one of the reasons series networks really shouldn't be used. I don't know what genius at Magnepan decided to switch all of the speakers to this configuration, but they should have left well enough alone.
    
    Dave.
    - RE: I agree with you, Dave but ... - neolith 08:11:37 11/26/21 (1)
      As you are well aware, the one advantage of a 1st order series XO is that the output curve (electrical) remains flat regardless of changes in the impedances of the drivers. This might be an advantage for cone drivers (woofers) that heat up and change impedance with use. Not so much for the planar since the heat is rapidly dispersed. Also, if the sensitivities of the drivers are the same then one gets a very nice flat acoustic output curve. OTOH it is highly unlikely that this condition is met so this advantage is somewhat moot and by varying the 3db points of the LP and HP filters, it may be possible for a parallel xo to compensate for acoustic "bumps". I vote for the parallel configuration.
      If Magnepan had stuck with the parallel configuration, biwiring and biamping would be a lot easier for the DIYer.
      
      "Our head is round in order to allow our thougths to change direction." Francis Picabia
      - RE: I agree with you, Dave but ... - Davey 08:16:01 11/26/21 (0)
        
        In Reply to: RE: I agree with you, Dave but ... posted by neolith on November 26, 2021 at 08:11:37
        
        No, I'm not well aware of that. :)
        Series crossovers tend to sum 'electrically' (an important distinction) flat. However, whether that is an advantage (or not) acoustically is project specific.
        And impedances of the drivers will alter the crossover characteristics regardless of whether it's series or parallel.
        Dave.
        
        Edits: 11/26/21
    - there is one very good reason series xo's are used - Story 07:22:46 11/26/21 (17)
      they are superior to parallel. I found this out 25 years ago with the integration of an Altec 511 horn to a 515 woofer after reading about series xo's somewhere, maybe it was Fulton. They are much more phase coherent and it was slap you in the face obvious comparing the 2.
      
      THE problem with them is the power to the drivers because the series xo's are only 6db/octave. This is with plain series types but maybe they have figured a way to make the slopes more steep and remove more of the lowest frequencies making their way to the mids and tweeters which would increase power handling.
      - RE: there is one very good reason series xo's are used - Davey 08:05:01 11/26/21 (16)
        
        In Reply to: RE: there is one very good reason series xo's are used posted by Story on November 26, 2021 at 07:22:46
        
        Total speculation. They are not inherently more phase coherent.
        And, series crossovers are not limited to 6db/octave.
        
        The reason Magnepan has switched is for practical concerns vice performance.
        The component values required are smaller (relatively speaking) and allow a crossover physically much smaller than previous ones. This allows (among other things) to dispense with the large external crossover box on the larger models.
        
        Dave.
        
        maybe you view it as such - Story 14:01:37 11/26/21 (13)
        
        In Reply to: RE: there is one very good reason series xo's are used posted by Davey on November 26, 2021 at 08:05:01
        
        and that's too bad for you. I know what I hear succinctly. Do what you want to
        
        RE: maybe you view it as such - Davey 17:05:42 11/26/21 (12)
        
        In Reply to: RE: maybe you view it as such posted by Story on November 26, 2021 at 14:01:37
        
        My opinion is based on decades of experience working with speaker systems.
        There are trade-offs in all speaker systems, but let's not be making statements about series crossovers being "superior."
        Clearly, they have a use case in some designs, but (generally) they are not the best option.
        As usual with most things audio, Rod Elliot has an excellent write-up on the trade-offs with high-level crossovers.
        https://sound-au.com/parallel-series.htm
        Dave.
        Parallel versus series (Open in New Window)
        
        Edits: 11/26/21
        
        so what, so is mine - Story 04:12:58 11/27/21 (11)
        
        In Reply to: RE: maybe you view it as such posted by Davey on November 26, 2021 at 17:05:42
        
        decades, yes decades. Anyone who views this can take my advice if they wish and build 2 xo's and verify this for themselves.
        
        RE: so what, so is mine - Davey 07:52:54 11/27/21 (10)
        
        In Reply to: RE: so what, so is mine posted by Story on November 27, 2021 at 04:12:58
        
        It's interesting that before the X.7 series Magnepan was using parallel crossovers on most of the their models for 40+ years. Why do you think they did that??
        
        Dave.
        
        why? - Story 08:46:59 11/27/21 (9)
        
        In Reply to: RE: so what, so is mine posted by Davey on November 27, 2021 at 07:52:54
        
        because they discovered the superiority of series in sound Q
        
        RE: why? - Davey 09:20:22 11/27/21 (8)
        
        In Reply to: RE: why? posted by Story on November 27, 2021 at 08:46:59
        
        It took them forty years to discover that? :)
        
        What do you think of the sound Q of bi/tri-amped systems using line-level crossovers with no high-level crossover??
        
        Dave.
        
        not quite - DrChaos 11:17:34 12/02/21 (1)
        
        In Reply to: RE: why? posted by Davey on November 27, 2021 at 09:20:22
        
        I think the SMGa also had a series crossover, and it has been often regarded as a particularly outstanding and sweet sounding model.
        
        Also the main driver properties themselves changed to QR from round wire, and of course electronic design tools and measurement equipment is notably superior to years past.
        
        RE: not quite - Davey 17:28:57 12/02/21 (0)
        
        In Reply to: RE: not quite posted by DrChaos on December 02, 2021 at 11:17:34
        
        That's why I said "most of their models" a couple of posts back. :)
        I'm well aware the SMG had a series crossover.
        Dave.
        
        Edits: 12/02/21
        
        RE: why? - Story 10:22:06 11/27/21 (5)
        
        In Reply to: RE: why? posted by Davey on November 27, 2021 at 09:20:22
        
        I'm now a fan of simplification and do passive from one amp. I've tried biamping as I've had many amps at any one time but it was too bothersome and just complicated things too much so I stopped doing it. I have Quad ESL 57's and they are my lifelong reference since 1975. I use them from 100hz up and have regular speaker cloth covering them instead of the metal grills which opens them up and extends the top end considerably. My hearing limit is still 16khz. The quads sit on Morel 9" woofers and I also have 2-16" Altec's in the corners. I use a simple parallel network, coils on the woofers wound myself on laminated cores to the frequency necessary, and caps on the 57's which have a rather complex impedance curve. It took me research and trial & error to figure out the points etc but they integrate into my particular room very well. I've witnessed and been thru measurement rigors but I still use my ears in my room to integrate everything all together. I've done all this to the point that I am not compelled to screw with things and just sit back and listen to the sweetness in the music and not obsess.
        
        BTW for anybody, many years ago I had an xover program (I forget the name) that would allow plugging in all the info and variations you want including a built in database and it had all different kinds of speaker xovers including series. If it's not around anymore I'm sure there is something else.
        
        RE: "Quad ESL 57's" ... - andyr 17:01:48 11/27/21 (3)
        
        In Reply to: RE: why? posted by Story on November 27, 2021 at 10:22:06
        
        Very nice.
        
        What amp do you have driving them, S?
        
        A mate of mine has a pair, driven by some lovely Italian tube monoblocs (a mere 18w, I believe).
        
        I understand they are a pretty wicked load - so very few ss amps can handle them?
        
        Andy
        
        RE: "Quad ESL 57's" ... - BDP24 00:18:22 12/22/21 (0)
        
        In Reply to: RE: "Quad ESL 57's" ... posted by andyr on November 27, 2021 at 17:01:48
        
        A real good amp for the QUAD ESL ("57") is the Music Reference RM-10 (Mk.1 or 2). Roger Modjeski used the ESL as his load when developing the RM-10. Roger passed away a few years back, but his assistant (who still runs Roger's business) may have one left to sell, and they occasionally turn up for sale used.
        
        RE: "Quad ESL 57's" ... - Story 17:13:01 11/27/21 (1)
        
        In Reply to: RE: "Quad ESL 57's" ... posted by andyr on November 27, 2021 at 17:01:48
        
        I've had quite a few over the years but I'm down to a pair of Dynaco III's not stock per se, a Quad 405 that has a thorough updated rebuild, and my favorite a relatively unknown Kinergetics pure class A KBA75. I had a Levinson class A at one time but the 75 was just....better, what can I say, it has an effortless authority and clarity and I don't speak a lot of reviewer speak, I just listen.
        
        RE: "Kinergetics pure class A KBA75" ... - andyr 17:19:31 11/27/21 (0)
        
        In Reply to: RE: "Quad ESL 57's" ... posted by Story on November 27, 2021 at 17:13:01
        
        Very nice! :-))
        
        Andy
        
        RE: why? - Davey 12:36:08 11/27/21 (0)
        
        In Reply to: RE: why? posted by Story on November 27, 2021 at 10:22:06
        
        Nice setup. ESL-57's are on my bucket-list for a listen. I had a short opportunity with ESL-63's many many years ago.
        
        Dave.
        
        RE: there is one very good reason series xo's are used - neolith 08:21:39 11/26/21 (1)
        
        In Reply to: RE: there is one very good reason series xo's are used posted by Davey on November 26, 2021 at 08:05:01
        
        Dave, aren't the components of a series and equivalent parallel XO the same, just the wiring is changed? The elimination of the external box is a result of using a 1st order XO rather than the higher order XOs seen on the earlier models.
        
        "Our head is round in order to allow our thougths to change direction." Francis Picabia
        
        RE: there is one very good reason series xo's are used - Davey 08:27:43 11/26/21 (0)
        
        In Reply to: RE: there is one very good reason series xo's are used posted by neolith on November 26, 2021 at 08:21:39
        
        That would be true if you were talking about textbook alignments. But start skewing the curves around to tailor the acoustic responses and you will see what I mean. The inherent interaction of the series crossover limits what you can do in this regard.
        The classic example is the Magnestand MMG crossover. It's designing for a textbook electrical (and impedance) response, vice an optimized acoustical result.
        You are correct that shallowing of the electrical slopes in the newer models resulted in simpler networks. But, I maintain, the reason for doing so is practical and not performance.
        Dave.
        
        Edits: 11/26/21

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