I've had a pair of Magnepan MG-12 sitting here for over a year. I have to redo the goo holding down the wires on the right panel because I'm getting some buzz out of it on bass-heavy material. While I have it apart I'm going to redo the XO and probably set them in wood frames while I'm at it, basically do the entire Peter Gunn approach. I found his original XO schematic posted on the IA/MUG forum, which was based on the SMGa. However, many of the Magnepan models had parts selected to tailor the crossover point to that particular panel, and of course the PG parts list was an ever evolving work in progress. Also, I'd like to get a clarification on the below diagram because it doesn't make sense:
First, why is the panel on the left shown as "right speaker" and vice versa? I suspect it has to do with flipping the panels but I still can't get my brain to understand it. Also, where is the resistor for the tweeter? PG quite clearly talked about using a single resistor there.
If anyone has a recent schematic and parts list appropriate to my panels please DM me.
First, why is the panel on the left shown as "right speaker" and vice versa? I suspect it has to do with flipping the panels but I still can't get my brain to understand it. Also, where is the resistor for the tweeter? PG quite clearly talked about using a single resistor there.
If anyone has a recent schematic and parts list appropriate to my panels please DM me.
I think you just set the record for the fastest response to a thread in DIYA history!
BTW, PG said that storage wasn't a good place for these unless they were sitting in a cool and very non-humid environment.
BTW, PG said that storage wasn't a good place for these unless they were sitting in a cool and very non-humid environment.
The drawing is a picture of the wiring as viewed from behind the speaker.
An attenuator resistor would be placed in series with the tweeter (blue wire going to the panel).
I don't believe PG's crossover mod was based on any engineering. I would leave the stock crossover as is unless you thoroughly understand the speaker's design.
You may be interested in my article on Modeling the MG1.6.
Ed
An attenuator resistor would be placed in series with the tweeter (blue wire going to the panel).
I don't believe PG's crossover mod was based on any engineering. I would leave the stock crossover as is unless you thoroughly understand the speaker's design.
You may be interested in my article on Modeling the MG1.6.
Ed
Thanks for the detailed info Ed, it's very appreciated.
I'll have to review my convos with PG to be certain but what I was given to understand is that he had a friend who would model the crossovers for him in software. He called him his "CAD guy" and they'd been collaborating for a number of years. PG tweaked the parts values for certain speakers - and some panels like the 2.7 I believe required some re-design since they offered a midrange section in addition to the bass and treble of the typical Mag - but otherwise the crossover was the same across all the models.
So far I've found these speakers a lot more sensitive to room treatment than anything else I own now or in the past. I redid my room and gave these some serious listening with a wide variety of music. I found I liked some of the character and didn't like some of it. There was a little bit of harshness to the highs, despite the excellent image, that reminded me a little of the old MP3 sound. In the past I found this had to do with crossover components, either age in the case of lytic or poor choice in the case of film caps. When I pulled the bottom cloth up to look at the XO I was surprised to see Solen parts in there. Decent quality but of a very old series that isn't available anymore. I put new Solens in and took the attenuator jacks and the fuse out of the signal path. The sound didn't improve. I figured I'd look into replacements so I'd like to try the Gunn mod. His Magnestand approach appeals to me. The wood adds a nice visual note to the speakers that will pair very well with the old Bell O'Ghetti audio furniture I have here. If I decide I don't like it, I can always return to the old crossover or even go to an active setup at any time, all of which is made easier since the wood frames require an outboard crossover. In fact I could probably come up with a bunch of different ones and A/B them to see what I like.
I'll have to review my convos with PG to be certain but what I was given to understand is that he had a friend who would model the crossovers for him in software. He called him his "CAD guy" and they'd been collaborating for a number of years. PG tweaked the parts values for certain speakers - and some panels like the 2.7 I believe required some re-design since they offered a midrange section in addition to the bass and treble of the typical Mag - but otherwise the crossover was the same across all the models.
So far I've found these speakers a lot more sensitive to room treatment than anything else I own now or in the past. I redid my room and gave these some serious listening with a wide variety of music. I found I liked some of the character and didn't like some of it. There was a little bit of harshness to the highs, despite the excellent image, that reminded me a little of the old MP3 sound. In the past I found this had to do with crossover components, either age in the case of lytic or poor choice in the case of film caps. When I pulled the bottom cloth up to look at the XO I was surprised to see Solen parts in there. Decent quality but of a very old series that isn't available anymore. I put new Solens in and took the attenuator jacks and the fuse out of the signal path. The sound didn't improve. I figured I'd look into replacements so I'd like to try the Gunn mod. His Magnestand approach appeals to me. The wood adds a nice visual note to the speakers that will pair very well with the old Bell O'Ghetti audio furniture I have here. If I decide I don't like it, I can always return to the old crossover or even go to an active setup at any time, all of which is made easier since the wood frames require an outboard crossover. In fact I could probably come up with a bunch of different ones and A/B them to see what I like.
Your MG12 and my MG1.6 are similar enough to share the same foibles.
They have an amazing ability to disappear on recordings made with two microphones (which are usually of orchestras, small ensembles, or solo instruments). These are the only types of recordings that can be used to assess accuracy.
Unfortunately, a lot of recorded music is not made that way. The resulting mix sounds phony (at best) to downright awful.
The MG1.6's dipole compensation is approximate. I can hear the tweeter coming in (which is the slight harshness that you noted).
Magnepan switched from parallel to series crossovers in the newer models. I suspect the series crossover improves coherency but does not offer as much low-frequency boost. I have not heard the newer models.
Ed
They have an amazing ability to disappear on recordings made with two microphones (which are usually of orchestras, small ensembles, or solo instruments). These are the only types of recordings that can be used to assess accuracy.
Unfortunately, a lot of recorded music is not made that way. The resulting mix sounds phony (at best) to downright awful.
The MG1.6's dipole compensation is approximate. I can hear the tweeter coming in (which is the slight harshness that you noted).
Magnepan switched from parallel to series crossovers in the newer models. I suspect the series crossover improves coherency but does not offer as much low-frequency boost. I have not heard the newer models.
Ed
Have you tried adding the resistor? I have the 12 and 1.7. Never had the need. The room is reasonably damped. Big persian rugs are your friend. No coffee table!
How about playing with aiming the speakers? ( I run the tweeters to the outside and aim the speakers half way to the listener... seat is about 12 feet away, speakers are about 8 feet from each other, five feet from back wall, three feet from side walls... the whole thing then offset by ~6 inches to the left. Open passage to the left and long fireplaces to the right... )
Change amplifiers? Tubes and Alephs and MOSFET sound the best. You need power. Lots of power. 100 wpc entry level. Recently I went to bridged F4 in an all balanced chain. The bass is astonishing. The treble is fine, I hear no harshness... perhaps the amps are the reason?
How about playing with aiming the speakers? ( I run the tweeters to the outside and aim the speakers half way to the listener... seat is about 12 feet away, speakers are about 8 feet from each other, five feet from back wall, three feet from side walls... the whole thing then offset by ~6 inches to the left. Open passage to the left and long fireplaces to the right... )
Change amplifiers? Tubes and Alephs and MOSFET sound the best. You need power. Lots of power. 100 wpc entry level. Recently I went to bridged F4 in an all balanced chain. The bass is astonishing. The treble is fine, I hear no harshness... perhaps the amps are the reason?
I spent a lot of time experimenting with resistors. My conclusion was that Magnepan got the stock response right.
The parallel crossovers in the MG12 and MG1.6 are very sensitive to the amplifier's output impedance. 0.5 ohms of output impedance will boost the midrange by 1dB. The crossover works properly with near-zero output impedance.
Harshness is due to tipped-up treble in pop music recordings. Classical music recordings can have "bite" in brass instruments and "delicacy" in string instruments, but the sound would not be described as "harsh".
Ed
The parallel crossovers in the MG12 and MG1.6 are very sensitive to the amplifier's output impedance. 0.5 ohms of output impedance will boost the midrange by 1dB. The crossover works properly with near-zero output impedance.
Harshness is due to tipped-up treble in pop music recordings. Classical music recordings can have "bite" in brass instruments and "delicacy" in string instruments, but the sound would not be described as "harsh".
Ed
I use to run a pair of ICE amps into the 12. They had exceptionally tight bass. As I remember, they have very low output impedance. If only the treble were so good.
Perhaps try an NCore amp? Years ago I bought an NC225MP board with a chassis but never got around to putting it together... perhaps I should.
I'm also using Kimber 8TC single-wire to the Maggies, so, I believe that's a low impedance cable as well.
Perhaps try an NCore amp? Years ago I bought an NC225MP board with a chassis but never got around to putting it together... perhaps I should.
I'm also using Kimber 8TC single-wire to the Maggies, so, I believe that's a low impedance cable as well.
I use my amp, which is (for all practical purposes) perfect.
My solution for poor recordings is not to play them loudly. 😉
Ed
My solution for poor recordings is not to play them loudly. 😉
Ed
Ed you've obviously put a lot of thought into the source, and Tony you're offering some good tips to try. You guys both made some good contributions so I hope you don't mind me combining this into one response.
When I started with these things I was just getting moved into that room so the furniture consisted of a single chair on a bare wood floor, rectangular, with tall windows behind the listening position. Basically, it was set up to fail. Classical music such as Wagner gave terrible results. The bass was deficient and muddy which I know had a lot to do with the room. The bottom third of the right panel seemed dead too. PG told me to check the fuse. It was intact but the plastic holder was broken into pieces. It probably wasn't making perfect contact. I installed a new holder and fuse, and the speaker seemed to be functioning fine after that. The drivers run vertically not horizontally, so it makes zero sense to me why the problem existed, or why this fuse service worked, but it did. Along the way I tried some early digital Sheffield Labs music, which sounded much better than the excellently recorded Wagner, but it wasn't perfect.
While this was going on PG gave me a good long lecture about room treatment, reinforced by the article and pics on his site. I did the first level of what he recommended, with carpet, curtains, and furnishings. On top of a huge area rug I added a 12 foot long, overstuffed suede theater couch. Heavy blackout shades covered two of the windows. There's a big slider behind the couch and I'm trusting the couch to take care of most of the reflections. I finished the room with a bookcase full of stuff on the right wall, and a huge CD shelf unit on the left. The sound improved immensely. The room is far from done, and it may end up getting combined with an adjacent room, but it'll do for now.
I tried a lot of amps. I started off with a Proton D1200, a couple of Carvers (200wpc and 375wpc), I think I used my Hafler DH500, before settling on a Perreaux 2150b for the best results. I used an NAD 1240 for the preamp, and a couple of different CD players. I played a lot with the positioning, and I found best results with them about 10 feet apart, with the support legs almost touching the baseboard and a slight turn towards the center. The outer legs are probably 6-7 inches away from the wall, to give you an idea of the toe-in. I also found these speakers are sensitive to wires. My home brew speaker cables came across harsh, but some ancient Monster cables sounded best. I think I'm using Ethereal interconnects now.
The thing about Maggies... they are relatively inexpensive.
But they are very sensitive to the components that drive them.
Your room is ~13 feet wide? I dunno, but seems to me, from your description, that you have your speakers almost in the corners?
One of the things we did in our living room was to get a rather large, 6' tall by 4' wide, CURVED glass curio cabinet. It sits on the far wall, about six feet from the couch. Does a wonderful job of sort of "diffusing" the back wave without absorption.
But they are very sensitive to the components that drive them.
Your room is ~13 feet wide? I dunno, but seems to me, from your description, that you have your speakers almost in the corners?
One of the things we did in our living room was to get a rather large, 6' tall by 4' wide, CURVED glass curio cabinet. It sits on the far wall, about six feet from the couch. Does a wonderful job of sort of "diffusing" the back wave without absorption.
The room is a shade wider than 18 feet, and close to 14 feet from the LCD panel to the back wall. I have a flattened U-shaped 12 foot wide theater couch sitting on top of a 10 foot wide area rug that goes from the TV wall back to couch, where its just long enough to cover all of the foot area in front of the couch. The speakers are 8 feet apart and as close to the back wall as I can get, with the outside feet about 6-8 inches off the wall for the toe-in.
Actually I should say "were", since I took them out of service until they're sorted out. I switch between a nice assortment of floor standers and bookshelf on stands in the meantime.
Actually I should say "were", since I took them out of service until they're sorted out. I switch between a nice assortment of floor standers and bookshelf on stands in the meantime.
Magnepans need some space. If you run your speakers less than four feet from the back wall it's just not enough. Less than two feet is not good at all.
What I do is move the speakers into position for listening and bring them back against the wall when not. The Persian rug has a nice pattern so I know where to place the speakers without resorting to tape on the floor.
I've thought of using the 12s in my HT, but it would require me to put them too close to the back wall. My current speakers in there are about 18" deep and the front sit about 24" from the back wall... so, having 20" from speaker to wall would be problematic... so they are kept in the box and the 1.7 are in duty.
I keep thinking of going quad... but where do I put those 12s?
It seems like you have your set up on the short wall? Can you flip it around and put the TV along the long wall? Then you might have more space to give the speakers more depth behind them. Even though they will always sit in front of the TV screen.
What I do is move the speakers into position for listening and bring them back against the wall when not. The Persian rug has a nice pattern so I know where to place the speakers without resorting to tape on the floor.
I've thought of using the 12s in my HT, but it would require me to put them too close to the back wall. My current speakers in there are about 18" deep and the front sit about 24" from the back wall... so, having 20" from speaker to wall would be problematic... so they are kept in the box and the 1.7 are in duty.
I keep thinking of going quad... but where do I put those 12s?
It seems like you have your set up on the short wall? Can you flip it around and put the TV along the long wall? Then you might have more space to give the speakers more depth behind them. Even though they will always sit in front of the TV screen.
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The tv is on the long wall. I'm sorry Tony, I think I'm being too wordy and it's messing up the description. Let me try this again...
Room: 18' wide x 13'6" deep
- tv and speakers on the long wall
area rug: 10' wide x 8' deep
- the rug is centered on the tv, wide edge against the baseboard beneath the tv
couch, mild u-shape : 12' wide
- the couch is a 4 seater, with a 2 person center seat flanked by wedge-shaped storage consoles, with a single recliner outboard of the consoles at either end
- the center section of the couch (2 person linear side-by-side config) is parallel to the tv wall, and comes up to the edge of the rug
- the distance from the center two seats (hifi listening positions) and the wall is just over 8'
- the distance behind the center two seats and the rear wall is about 3'
MG-12 : placed against the long wall, centered on the tv, and spaced 8' apart, tweeters out. The speakers are close to the wall. toe'd in by pulling the outside leg 6 inches into the room
Now the problem here is that if I use the 4' rule you mentioned for back-spacing then I'm going to have only 4' to 5' from my ears to the horizontal alignment of the speakers. And since this is a mildly U-shaped couch then the speakers are really close to the two end recliners. I can't push the couch any further back without interfering with egress through the balcony doors behind the seating. I suppose I could try 2' backspace but then I'm just 7' from the speakers to the seats.
If I combine this room with the one adjacent, I'll have 32' wide and 15'5" deep. Better - and perfect for something like Polk SDA - but still not perfect if I'm supposed to have 4' of spacing behind these speakers. Now I'm wondering if I should just button these up and sell them instead of trying to redo my house to accommodate them.
Room: 18' wide x 13'6" deep
- tv and speakers on the long wall
area rug: 10' wide x 8' deep
- the rug is centered on the tv, wide edge against the baseboard beneath the tv
couch, mild u-shape : 12' wide
- the couch is a 4 seater, with a 2 person center seat flanked by wedge-shaped storage consoles, with a single recliner outboard of the consoles at either end
- the center section of the couch (2 person linear side-by-side config) is parallel to the tv wall, and comes up to the edge of the rug
- the distance from the center two seats (hifi listening positions) and the wall is just over 8'
- the distance behind the center two seats and the rear wall is about 3'
MG-12 : placed against the long wall, centered on the tv, and spaced 8' apart, tweeters out. The speakers are close to the wall. toe'd in by pulling the outside leg 6 inches into the room
Now the problem here is that if I use the 4' rule you mentioned for back-spacing then I'm going to have only 4' to 5' from my ears to the horizontal alignment of the speakers. And since this is a mildly U-shaped couch then the speakers are really close to the two end recliners. I can't push the couch any further back without interfering with egress through the balcony doors behind the seating. I suppose I could try 2' backspace but then I'm just 7' from the speakers to the seats.
If I combine this room with the one adjacent, I'll have 32' wide and 15'5" deep. Better - and perfect for something like Polk SDA - but still not perfect if I'm supposed to have 4' of spacing behind these speakers. Now I'm wondering if I should just button these up and sell them instead of trying to redo my house to accommodate them.
Yes, I got my facts backward, you were correct in your description to begin with.
Seems to me like your setup is not conducive to get the best from Maggies. Maybe some mini monitors on stands and woofers right below them.
Seems to me like your setup is not conducive to get the best from Maggies. Maybe some mini monitors on stands and woofers right below them.
I agree with Ed.
My room is effectively 22 by 14... Talon's room is not small for the small Maggies. I run mine along the "far" short wall. Our TV is in another room. You could keep the TV in the room. in the middle of the short wall, move the speakers four feet from the wall for music and two feet for HT.
This would also give you room to install surround speakers behind you, heck you could likely do a 7.xx set up. Having side and rear surrounds makes a big difference for the HT.
Heck, if you could do a 35' by 15.5' and put the speakers along the short wall, you have the potential for a very nice room for Maggies. Put your dining room at one end and the HT/Audio at the other 2/3rds. You'll likely have to move the couch off to the side, against a side wall, so you can walk around it.
My room is effectively 22 by 14... Talon's room is not small for the small Maggies. I run mine along the "far" short wall. Our TV is in another room. You could keep the TV in the room. in the middle of the short wall, move the speakers four feet from the wall for music and two feet for HT.
This would also give you room to install surround speakers behind you, heck you could likely do a 7.xx set up. Having side and rear surrounds makes a big difference for the HT.
Heck, if you could do a 35' by 15.5' and put the speakers along the short wall, you have the potential for a very nice room for Maggies. Put your dining room at one end and the HT/Audio at the other 2/3rds. You'll likely have to move the couch off to the side, against a side wall, so you can walk around it.
Unfortunately that rearrangement wouldn't work for me. Never mind the shotgun effect of going on the short wall (what PG called the "coffee can") this room is going to serve double duty as both a 2 channel hifi listening area as well as a home theater. The TV will be staying, and I can't tell me wife with a stray face to squeeze past the couch to get across the room. And if I did go ahead and do that, I'd have a wall of glass windows on one side and drywall to the other, which is going to lead to weird reflections. I'm dealing with that now since my SDAs are downstairs in the living room, with the left speaker <3' from a wall and the right channel has 16 feet of empty space between it and the other wall. Both the SDA and the MG12 will get moved upstairs to that hifi room if I expand it, so I can take advantage of that wide space.
I'm going to redo these Mags and test them out. If I can keep the backspace to 2' or less I'll keep them. Otherwise, they go.
Now, I have to find that MG12 crossover schematic.