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Dear All,this is my first post - so i'd like to say hello to all Maggies fans and forum users !
i need some support regarding Magnepan MG12 crossover, here is the story :
i've got my Maggies as a second hand with modded crossover, what i would like to do is to bring it back to the original specs using better quality components (air coil, better caps).
After mod my crossover has no longer cable coluring (white, brown, blue etc) - every cable is black ..
The thing is, that previous owner did some mistake and while listening to the speakers i can hear they are out of phase...
Changing polarity in one of the speakers do the job and everything sounds o.k then...I'd like to correct this problemn during my rebuilding project..
i have already schematics for MG12 - but does anybody have pictures of original not modded crossovers..?
What is polarity of both bass/tweeter coils in left\right speaker (how to recognize it...?) so i can hook them up properly to rebuilded crossovers...Many thanks for any help !!
Edits: 08/29/14Follow Ups:
Told ya :) If it's info on Maggies you seek, this is the place. Hang around a while. Lot's of experience & knowledge to be shared.
The wiring on the Magnepan crossovers can get confusing because the left and right speakers are mirror images. Having all the wires black does not help matters and also it is clear that the original owner got confused so you cannot trust that he did not reverse the polarity of the tweeter and woofer on the each speaker (leaves a big hole at the crossover point).I believe the orginal color coding on the MG-12 is the same as on the MMG -- brown (+) and blue (-) for the tweeter and black (+) and white (-) for the woofer. So for the left speaker (+ -) (- +) where the first set is the tweeter and the 2nd set is the woofer. On the right side its (- +) and (+ -) --woofer then tweeter. Or with colors brown-blue white-black on the left and white-black brown-blue on the right.
You may have difficulty finding a 2.8 mH inductor as the standard E-12 size is 2.7 mH. I wouldn't worry about a 0.1 mH error -- you will not be able to hear the difference. Also you will probably find out that your replacement parts will not fit into the speaker. You will need to build an external box. This is a good thing as it will isolate the crossover from the vibrations of the speaker.
Finally one suggestion - omit the attenuator jumper and the fuse but put a 10 uH choke in series with the tweeter.
Edits: 08/29/14
Dear neolith,
what a beautiful dogs you have.... !
I also likes these fellows and have at home two German shepherds and one little Yorkshire terrier ...
they are proud members of our family... :-)
BIG thanks for explanation !
I understand from MG schematic, that both crossovers are same but only difference is how they are hooked up into the panels.
From your post and schematics i will be able to properly rewire and connect MG12 panels - that means i can start my work (i have all parts ready). !
You are right - since left/right panels are mirror images it is easy to make mistake - and such simple mistake is now affecting the sound of my Maggies...
Of course i can reverse polarity at speakers terminals, but i have a question here - would it be the same if + and - signals will flow through the crossover in opposite ?
I mean to have negative on 33uF tweeter cap instead of positive signal...?
Does such reversal influence the sound or change crossover electrical properties..?
The ladies in the picture are Lolita and Conchita and they are Havana Silk Dogs. Lolita (on the left) is quite the beauty queen and is a Grand Champion.
It will make no difference if you put the cap on the positive leg or negative leg as the plus and minus designations are arbitrary and could just as easily be named Lolita and Conchita.
Gents,
Thank you for your help !
Let me work now and i will be back with my observations right after job is done.
Neolith... i like Conchita... :-)
That polarity issue has confused many folks through the years. A left/right polarity switch is pretty easy to identify audibly, but it's the correct relative polarity between tweeter and woofer that has caused much misunderstanding. Be sure you understand that fully when making all your connections.
Dave.
Hi Dave,
i'm not sure what you are saying.... could you pls use some other words to tell what's on your mind..? (unfortunately english is not my native language)
MG12 crossover is not a very complicated one - what could be an issue (and it is, in my case) is polarity of left and right panel - it is mirror reflexed, so without proper schematic it could be tricky to hook up everything in the right way.
I understand, that i need to be consistent and hook in correct polarity not only left and right panel but also tweeter and bass section on each of them.
This should be not difficult task thanks to posted in this thread schematic.....
Because of the crossover alignment, the tweeter and woofer are connected with opposite polarity. If you look at the four connection lugs at the bottom of each transducer, the polarities are arranged as - + - +Here's a marked up schematic for you:
Dave.
Edits: 08/31/14
Dave,
I think that picture is in error - the brown and blue wires are reversed. Typically blue is negative (European system) and should be connected to the red wire and the brown is positive and connected to the black (via the attenuator jumper and fuse). Your marking of the + and - or the tweeter is correct.
No, it's not in error. This is why I always say the polarity issue is so confusing. :)Forget about the wire colors and consider just the polarities of tweeter and woofer transducers. The laid down traces never cross over each other so this means the polarity connections are - + - +.
Woofer - tweeter on one speaker and tweeter - woofer on the other speaker, but still - + - +.Or, if you consider the other side of the speaker the "front" of the speaker, then the labeling would be + - + -. (You can see why this gets so confusing.) :)
No consider the crossover itself still forgetting about wire colors. The alignment means you need an opposite polarity connection between the woofer and tweeter so this means the woofer (+) and tweeter (-) transducer connections should ultimately find their way to the input red post.
Cheers,
Dave.
Edits: 08/31/14 08/31/14
I have to say, that now i'm really confused....
I hooked up everyhing according to schematics posted by neolith and things sounds good....
then i rewire crossover accordingly to Dave's suggestion.... no change in sound .... strange..
Hmm what is the right setting...?
Should i stick to schematics posted by neolith or maybe Davey's suggestion is the right one...
Once again - i checked both and there is no difference in sound between those two...
Well.... NOW PLEASE HELP...... :-)
My "suggestion" is not mine. That is the Magnepan configured way they leave the factory.
I suppose it's possible the other configuration might yield an audible improvement in a weird circumstance with the right boundary reflection, or some other contributing factor.The deep interference null Neolith has shown on his graph would indeed be measured with the wrong configuration, but only if the microphone were in the proper location horizontally and the speaker measured in anechoic conditions.
The fact that you can't easily hear the difference between the two configurations doesn't surprise me. Your listening room is a complex acoustic environment and is factoring in. Plus, you're using music which is a poor source material for this testing.
I like Neo's suggest to play some midrange signals and see which configuration sounds louder. Preferably this would be some band-limited pink noise. That would easily make the difference audible.Cheers,
Dave.
Edits: 08/31/14 08/31/14
Hmm .. I rewired both crossovers according to MG12 schematics posted by Davey - then i hooked them up to the panels according to neolith's schematics of MMG....
is this correct....?
or am'i out of phase somewhere..?
Post a photograph of your wiring configuration.
Dave.
I can not post pictures......
I have to use web proxy to access Audioasylum - and because of that - no pictures.. at least i don't know how to upload them in such conditions.
I'll try to describe what i have :
- both panels 1 and 2, looks like on neolith's schematic of MMG (posted in this thread)
- my MG 12 crossovers are built strictly according to Davey's schematic of MG12
- i hooked everything up - panel 1 and 2 using neolith schematic of MMG
So, from my perspective - if MMG panel is equal to MG12's (at least same polarity of bass and tweeter section) i should be fine.....
assuming that "+" and "-" locations are the same for both panels, all i need, is to be careful about properly feed (hook up) crossover wires.
They are color marked as : brown, black, white, red, blue which represents polarity...
In other words - i hooked up brown, blue, black, white cables marked on MG12 schematics respectively to neolith's MMG schematics, where we can see cable colors combinations on panel 1 & 2..
Is this correct...?
I'm not sure where the misunderstanding is coming from here. I've marked up the MG12 schematic with polarities and identified the destination polarities on the transducer terminals. Just wire it up minus-to-minus and plus-to-plus and you'll be configured per the Magnepan factory configuration for the MG12.
Dave.
Dave - just one thing more - if you take a look on the speakers 1 & 2 (like in neolith post with MMG schematics) which terminals are negative and positive for bass and treble panel ?
Is it on speaker 1, tweeter section "-" "+" and for bass " "-" "+"
and on speaker 2, bass section "-" "+" and for tweeter section "-" "+"
If yes - i'm fine - if no i'm lost.... :-)
Yes, that would true.
That shouldn't be confusing because you can tell which side of the speaker the tweeter is on just with visual observation.
Dave.
O.K - my project is finished.
Maggies are back to life and i'm happy one to enjoy their great sound.. !
12QR are my first Magnepans - i was worried about bass reproduction - but there is nothing to be worry about...
OK, very deep bas could be more audible but what we have, is so good quality and so well integrated to the rest of the frequency that i don't have a feeling that something is missing - so i don't need subwoofer.
Once again big thanks for your patience and help !!!!
As should be. Great to see that you got it right! Bass from Maggies can be tricky to get proper in some environments. Evidently you got the best essence of it...not "a ton of bass" just "more of the detailed & textured lower bass"?
You don't mention the fabulous imaging that they can deliver in many places...but give them time for the parts to break in and perhaps this will start to show up.
BTW, if the time comes when you want to push the 12's further, we'll be around.
Enjoy!
Don't be afraid to experiment with placement of you Maggies. Keeps notes on distances to the front wall & side walls. When you hit that right spot, it's Maggie Magic time ;)
LOL! Rickey, "magic" is right. However, you do remind me that sometimes we have to "build up the proper location". Also, imaging can be easily thrown off by other factors.
Still, when it all falls into place, it IS magic!
i must admit, that Maggies resolution and in the same time lack of sybilants or any other harshness is magic. It is not easy to match this level of presentation ... and this stereo image....vocals....
I spent some time with positioning but it looks like i was lucky - just one day of fooling around the room and i've got sweet spot.
Now i wonder how higher models sounds... :-)
BTW - a question for Maggies experts - how would you rank MG12 in beetwen other Maggies..?
I'm just curious where the improvment is most visible (audible.. :-) )
aha - just one more thing - i decided to keep this "bad" fuse in the cicuit - just in case if too much ampers would like to flow through my semi ribbon.... is this worth to use audiophile grade fuse instead regular one...??
If your room allows it, you should try the HK/Limage setup. Quite a few of us have tried it to great effect. It works best in shoe box shaped rooms with wall length proportions of 1.1 to 1.4 (1.3 seems best) and 1.6 to 1.8 (1.63 or thereabouts is best).
Square rooms and 1:1.5 and 1:2 don't work well for the setup.
The speakers are set on the short wall and
pulled about 40$ into the room (e.g. 8' in a 20 ft long room.)
and setup 1 ft or so from the sidewalls
with the tweeters in
and the speakers facing dead forward
The listening seat is approximately 2 ft from the back wall.
You can look at setups worked out by Mark Man and Wazoo among others. You need to fine tune all the measures, but the initial figures usually do quite well.
well .. this is not available to me - my room is not that long....
BTW - actually my room is nearly square and i' surprise about quality i quantity of bass MG12 can offer...
I will give a try to the audio fuse... and write here about my impressions..
Cheers !
I'll leave the other stuff for later and/or for others; but regarding the fuses, please consider this for now.
For reference, QR tweeters are pretty darn strong. My MMGs have always had the fuses off*. These days, each tweeter has well over 200 watts of power connected directly (under line-level bi-amping). Despite my dumb errors in the past (full range signals by accident) they are merrily tweeting on.
If you cannot hear a difference between the current fuse and a straight wire in its place, worry not. Leave the fuse on. OTOH, if you do like it more without the fuse, you can leave it off at this stage and keep the wire. Then you could perhaps invest on high-end fuses. They are pricey and will be overkill in most cases. That said, you do live in Europe...replacing or fixing the 12's is not as easy as it is here.
*(this may not be wise or advisable on the high-end true ribbon tweeters. Still, some of our inmates do run true ribbons without a fuse...very carefully!)
To be sure everything is set up correctly:
1) Check that the two speakers have the same polarity: Play a stereophonic pink noise and verify that the sound seems to be centered between the speakers - if its diffuse reverse the connection to one speaker only.
2) Verify by playing a high frequency tone (> 2000 hz) and again confirm the sound is centered.
3) Do the same thing with a low frequency ( < 60 hz) signal.
To verify the correct polarity between a woofer and tweeter. Play a signal at the crossover point (~560 hz) into one speaker only. Without changing the volume reverse the wiring to the tweeter only. The louder sound is the correct relation. (Caution: Shut off your amp before making any changes).
Here is a Bode diagram for the MG-12 with the tweeter inverted compared to the woofer and with the tweeter not inverted.
Welcome to the forum, K!
I am still at work but will check later when I get home to see what I can dig out for you this evening. Hopefully, someone with 12's already has this specific stuff and will post it soon anyway.
In the meantime, have you already bought the crossover parts? Do you have a list of specific candidate parts? There are a few of us here who may have various "tweaking ideas".
JBen,
Thanks for input - i will wait for your next post...
Here are my new parts for little crossover project :
2x Jantzen wire air coil 2.8mH, 0.443 ohm
2 x Mundorf Mcap EVO Oil kondensator 0,10 uf (shunt for tweeter)
10 x Mundorf Ecap 70 VDC PLAIN 10,00 uF (5x10uF per side electrolyts for bass)
2 x Mundorf Mcap 33,00 uF
2 x Mundorf Mcap 630 0,10 uF (shunt for bass)
Wile choosing above i kept in mind to use original MG 12 crossover space - i want to keep them as close as possible to stock units - so, no external crossover.
I think, that biggest improvement will come from air coil in bass and Mundorf Mcap shunted with Mundorf Evo Oil in tweeter section....
I like Mundorfs for the sound and i hope that this combination will do the job in Maggies.
Because i was not sure about bass caps (if they can influence the sound in such place of crossover) i decided to stay with elcos and upgrade only their quality - so once again good old Mundorfs..
The Ecap electrolytics though much better than older low ESR electrolytics are still not to the level of the other caps you are using. I would suggest you use MKPs instead.
The other Mundorfs I assume are MKP metalized polyprop. They are very good. The oil cap for the tweeter is a very good idea.
Of course MKP's are better than Electrolytics .
But they are much bigger too, so no matter if i use single 50uF, or try to combine 50uF from smaller capacities - there is no way to mount them into MG12 crossover space....
I do not want to have the external one, so this is why i have to stick to electrolytics....
There are lower voltage square stacked film caps that don't occupy as much space, lots of models from Wima for example. Perhaps those would fit.
Later, if you have an extra pair of power amplifier channels, ask us about line-level bi-amp options for Maggies. These can be built active or passive (the latter, rather easily and inexpensively). With these, the issue of the large external xover boxes could be "mostly resolved". More importantly, the true potential of those 12s could be easily tapped.
Have fun! (and pls let us know how it goes)
Super! Neolith made our lives easier with this schematic, which you seem to have understood well.I see that you are all set with new crossover parts. We will have to wait and see how you find them performing after a break in period. IMHO, Neo's mention of a separate crossover box is something that you should consider, along with his other suggestions.
On the question to Neo about polarity inversion, it matters. You should be able to hear it for yourself by testing it with some recordings.
The simple fact is that most Maggies have magnets on only one side of the Mylar. The Mylar moves "out" -- away from the magnets -- with different dynamics than when it moves "in" -- toward the magnets.
This asymmetry will affect the average recording in the same fashion: dynamic impact will be better felt with one polarity vs the other. It actually is more complicated than this but this is the bottom line. The behavior changes, and it is not just about dynamic impact, which is just the most obvious sign.
The other part of your question has to do with the xover parts in one or the other polarity. Some caps do tend to behave differently depending on polarity, though usually in subtle ways. The explanation for this is longish. I'll leave it for others to elaborate. For now, you may want to explore forums where the Mundorf caps are discussed. They may have some hints if polarty should be kept in mind. OTOH, coils, if they are alone, have no such sensitivities, AFAIK.
Finally, "bass caps" as you call them do affect the sound. While I no longer use a regular xover, my [ancient] MMGs had one similar to what your 12 have (newer MMGs are different). Before I biamped them, my initial experiments with a regular xover showed how sensitive the Maggies can be to the wrong shunt cap. Both timbre and "speed" can suffer. You should be fine with the Mundorf, I think. However, if you notice less dynamic impact than before...this is one good place to look. Yet, one needs to wait out the long break-in period first.
Edits: 08/30/14 08/30/14 08/30/14
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