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In Reply to: RE: Magnepan 12QR crossover question posted by Davey on August 31, 2014 at 08:24:29
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.
Follow Ups:
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.
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