[Waker]

I am reading of at least two mod approaches to improving Maggie sound clarity.  John at Magnestand favors using hardwood frames to dissipate the vibrations of the mylar drivers into the frames. This idea allows the driver to recover quickly. Others have made frames that decouple the tweeter from the bass driver, and others have mentioned a more massive frame, such as Corian in place of the stock MDF, which would keep all the energy within the mylar driver.  Which idea gives better results?     

[jk@home]

In my limited experience with my modded MMGs, the wood frames (at least the ones built “Gunned” style) which in theory absorbs vibration, also adds mass to the speaker. And also IMHO, by adding extra damping material on top of that improves the performance even more.

I say “which in theory” because I personably didn’t do an A-B comparison between my wood  and MDF frames. My frames are more on the line of this design:

http://orion.quicksytes.com/content/MMGframe.htm

But other than that, were based on the “Gunned” mod, which included help from John of Magnestand in getting my series crossover sourced, and other info.

I’m still in the process of finishing the mods, need to complete the external crossover boxes and plan to cover the frames with a MG12 sock. As of right now, the speakers weigh close to 50 # each,  how’s that for extra mass.

I’ve also added Cascade VMAXMP to the back pole pieces (know as “the Razor mod”), and may even slap more on the frames before they get covered.

http://db.audioasylum.com/cgi/m.mpl?forum=mug&n=155318&highlight=Cascade+V-MAXMP&r=

So I guess I'm in the camp that thinks one should remove as much unwanted vibrations from the panels as possible. Works for me (since the posts below, I've turned my panels back around to mylar out, prefer it that way).

http://db.audioasylum.com/cgi/m.mpl?forum=mug&n=157804&highlight=Deli+frames+in+the+oven&r=










 

[andyr]

I am reading of at least two mod approaches to improving Maggie sound clarity.  John at Magnestand favors using hardwood frames to dissipate the vibrations of the mylar drivers into the frames. This idea allows the driver to recover quickly. Others have made frames that decouple the tweeter from the bass driver, and others have mentioned a more massive frame, such as Corian in place of the stock MDF, which would keep all the energy within the mylar driver.  Which idea gives better results?

Reading what you've written, Waker, I believe you are slightly confused between the different options you put forward - so let me give you my take on this.  Declaration: I have gone down the "Gunn" path in terms of using hardwood frames for my Maggies.   

As I understand it, John's theory is that:
* MDF is a pretty inert material, compared to "real wood".
* because MDF is made of dust and glue, it has no "fibre structure".
* when the mylar flaps, it causes the whole driver assembly (in particular, the "pole piece" - the holey sheet of metal which supports the magnets) to vibrate.
* this vibration of the pole piece interferes with the "pure" vibration of the mylar - which is what we want to listen to! 
* because MDF has no fibre structure, when vibrations from the pole piece hit the MDF, they are just reflected back into the driver assembly.
* in contrast, real wood has a fibre structure which is able to absorb some of these vibrations - so less gets reflected bck into the driver assembly.
* hence hardwood-framed Maggies sounds better (clearer).

Your point about "frames that decouple the tweeter from the bass driver" is only relevant to those Maggies which have true-ribbons.  Stock 2.5s/2.6s, IIIs/IIIas/3.Xs and 20s/20.1s all include the ribbon in the one frame; only the T-IV and the T-IVa had a frame for the mid & ribbon which was separate to the (2) frames each side for the bass panels.

Hoshi, on the Planar Asylum recently build separate frames for his 2.5 ribbons (as I had done with my 3-way "Frankenpans") and reported a significant improvement in SQ.

In terms of increased mass and substances like Corian - while many people have built hardwood frames, I don't think anyone has actually built Corian frames yet.  Yes, they would be more "massive" but they may in fact not be as good as hardwood ... because they lack the fibre which wood has.  Given the price of Corian, it would be an expensive experiment!    IMO, solid aluminium would be another interesting experiment.

John states that the density (ie. mass) of the wood doesn't seem to make any difference to the sound - and he's made a lot of frames out of many different woods over the years!     I'm not sure I agree with him, though - so I decided to go for mass with my first hardwood frames (for my IIIas) and used recycled red ironbark - a very hard, dense timber.  For my Frankenpan frames, I went with "Forest Red" which is not quite as dense.

Regards,

Andy

[rollo]

Great stuff men. I tell ya your perking my interest again in my 3As. Pipedreams have replaced them when I got into SETs.
  Anyways, has anyone consulted with Magnepan for an ultimate material and or frame/enclosure ? Just curious if they would help or recco anything as an alternative. Do they do anything different for the 20.1s ?

charles

[andyr]

Great stuff men. I tell ya your perking my interest again in my 3As. Pipedreams have replaced them when I got into SETs.

Charles

Don't forget you will need completely different amplification for IIIas.     Even on the ribbons, I doubt that a SET will do.

Anyways, has anyone consulted with Magnepan for an ultimate material and or frame/enclosure ? Just curious if they would help or recco anything as an alternative. Do they do anything different for the 20.1s ?

Magnepan have not shown themselves to be interested in spending the time to respond to "interesting" questions like that. 

As far as I'm aware (from seeing some pics someone posted after a factory visit), the 20.1 frame is MDF like all the others.  And they kept all the drivers in the one frame.

Regards,

Andy

[TomS]

Don't forget you will need completely different amplification for IIIas.     Even on the ribbons, I doubt that a SET will do.

Magnepan have not shown themselves to be interested in spending the time to respond to "interesting" questions like that. 

As far as I'm aware (from seeing some pics someone posted after a factory visit), the 20.1 frame is MDF like all the others.  And they kept all the drivers in the one frame.

Regards,

Andy

I've heard the stock 20.1's a couple of times in big rooms with big power and loved them both times.  One can only wonder how good they would sound with a "Gunned" frame/bracing setup or similar mod.  It would take some serious courage to just start ripping apart speakers that cost that much money to begin with.

[andyr]

I've heard the stock 20.1's a couple of times in big rooms with big power and loved them both times.  One can only wonder how good they would sound with a "Gunned" frame/bracing setup or similar mod.  It would take some serious courage to just start ripping apart speakers that cost that much money to begin with.

Unfortunately, I'm yet to hear some 20.1s.     But yes, in a hardwood frame they should sound even more amazing! 

They have a fundamental problem, though, IMO ... all 3 drivers are in the same frame (so the vibrations produced in the frame by the bass driver, shake the ribbon cage).  The old T-IV and T-IVa were the only Maggies which had a decoupled frame for the mid & ribbon - IMO they should come out with a "Statement" pair of 20Series which does this ... with magnets both sides of the bass & mid drivers.

Regards,

Andy

[josh358]

  Anyways, has anyone consulted with Magnepan for an ultimate material and or frame/enclosure ? Just curious if they would help or recco anything as an alternative. Do they do anything different for the 20.1s ?

charles

Jim Winey is on record as saying that metal frames would be better than MDF, but that they're too heavy to ship. He didn't say anything about wood. But in general, and while others would disagree, I think the same materials that work most effectively to minimize resonances in conventional enclosures are best for frames. That would likely mean aluminum, followed by Baltic birch ply. Maggies also benefit from some combination of mass and bracing to reduce the to-fro motion of the frames. There is also a school of speaker design that allows resonances, but tries to keep them musical. I'd say that the Magnestand is a planar example of that. The resonances of single-ply wood are more euphonic than those of an amorphous material like MDF.

[pelliott321]

I rebuilt IIIa's last year with lots of help from Peter GUNN (AA) and AndyR

I used a little different approach on my Padauk frames. There is no base per say. I have spikes (two)on each corner of the bottom of the frame and a support pole (Alum conduit filled with lead shot) from top center to the floor. AndyR's designed external xover is in a spiked damped box behind speaker.  I feel this better couples the frame to the floor.  I thinks the big heavy base that PG uses just stores energy.
I have recently purchased another set of IIIa's for spares and to experiment with.
I want (maybe wishful thinking) to build aluminum frames (Square stock tubing) and bolt just the panels and ribbon too. This will be the barest naked maggy. You will only see the panels.  The square stock tubing will be filled with lead shot and/or sand. Ribbon would definitely have its own stand.
 

[jk@home]

... That would likely mean aluminum, followed by Baltic birch ply...

Hey Josh. When I was originally planning my frames, I was looking at Baltic Birch ply. The type of construction I used (Davey's sandwich style) would of been much easier using two monolithic pieces of BB plywood.

PG talked me out of this idea, but I still think it would be neat to try as a substitute to all the wood joinery needed to do hardwood frames.

[pelliott321]

I used Kreg pocket screws.  It was a piece of cake
The difficult part was cutting the slot for the ribbon and all the routing for the rabbits for the panel and ribbon.   It just took time, I practiced on poplar.  My mantra was that this was my last speaker and I wanted it to look as good as it sounded.
I simplified things a lot by not using a base.   

[jk@home]

I used Kreg pocket screws.  It was a piece of cake
The difficult part was cutting the slot for the ribbon and all the routing for the rabbits for the panel and ribbon.   It just took time, I practiced on poplar.  My mantra was that this was my last speaker and I wanted it to look as good as it sounded.
I simplified things a lot by not using a base.

They look very nice! I used poplar for my frames, since I was going to cover them, didn't expect much. I had never worked with poplar before, it is a very easy wood to mill, cut, etc. Coated the frames with Minwax sealant, to slow down the expansion/contraction process. The finish turned out nicer than expected, but I still will eventually sock them, once I finish all other mods.

What are your crossover box construction details? I started making some out of MDF, to be filled with quartz sand. I'm still not satisfied with the finish/construction of the boxes, tired of messin with it.

Thinking now about going to a simple plastic container (like what Al Sekela of AA uses). Just me and the cat in the listening room anyway, no need for a "work of art" sitting behind the panel. Will be using Cardas "patented" binding posts, the nylon blocks should mount fine on the plastic.

I just have to make sure I keep the lid on the sand filled boxes, in case the cat gets an idea of her own.  Heading to Bed Bath and Beyond this morning...

[pelliott321]

I do not have pics handy here at work, I will try to post them tonight.  Even though they are hidden behind the speaker I decided to have them match the frames which are out of padauk and at the same time tie everything together with my walnut Janis sub-woofers.  So I have a heavy padauk base, walnut box and a padauk top with walnut accent.  the base is spiked to the carpet covered concrete floor. The padauk and walnut combo is interesting
I found that every time I had someone over to listen that never heard planers before (just too much fun) the first thing they do, after they close their mouth, is walk over and look behind the panels so I wanted an additional surprise with the xover box. 

[pelliott321]

here are some more pics

box is about 15LX5WX7H

All parts from Madisound, I just sent them Andys schematic and they suggested the parts

The Panel is very stable (can not tell from photo) about a 2degree tilt back (Ala PG)
The support pole is lead shot filled 1 inch aluminum conduit and spiked and weighted at the floor end.

[benie]

pelliott321 they look really sweet!!   Nice work!!
Your right about Andy + PG, both are very helpful.

[jk@home]

That's a good looking setup, sweet and simple. I think placing the boxes on the floor, decoupled from the frames makes sense.  I've talked myself into a  plan of drilling over sized holes in my bases, for a separate box platform with spiked legs coupled to the floor.

I see you have direct wire connections, no binding posts. After searching the usual places yesterday (BB&B, Target, Walmart, etc.) for plastic containers, now looking at ABS plastic project boxes  . I may do the direct wire thing myself, at least between crossover and speaker.

The dilemma is I don't want to commit to what amp to speaker cabling to use until after everything else is done, but by filling the boxes with sand, it will be a hassle to change cabling into the box after that. So, for now, need to keep binding posts there at least.

[Davey]

John,

I see you have yours orientated with the transducer side forward per the stock configuration.  Have you tried them the other way?  They certainly sound a bit different depending upon orientation, but I couldn't stand to look at the mylar side during listening.    (Unless, of course, they're going to eventually be covered with a sock.)

I can't believe placing the crossover boxes on the floor or on the speaker base is going to make any audible difference. 

Cheers,

Dave.

[pelliott321]

Davey, I did listen to them reversed (mylar out) when i was prototyping and decided that the differences were not important enough to warrant a change in design.  If I had put the mylar out I would have had to put a sock over it and that (I feel) would have taken away any advantage.

Plus, I know there is no proof here, but I have a gut feeling that the the positive pulse needs to go  toward the magnets not away from the magnets 
I know I will get blasted for that last statement and as I said it is just a gut feeling   

[Davey]

Pulse towards (or away) is an absolute polarity issue and a complete waste of time to worry about....unless a listener is going to evaluate every piece of software in their collection with both polarities and then label with a preferred direction (if there is one) for subsequent playings.

Some Magnepan owners have advocated that (absolute polarity issues aside) one side or the other should be orientated toward the listener because they sound better that way.  However, I'm not aware of any published objective data backing up those claims.  It's all subjective evaluation......which is, by definition, of little value to a larger community.

Cheers,

Dave.

[andyr]

I can't believe placing the crossover boxes on the floor or on the speaker base is going to make any audible difference. 

Cheers,

Dave.

Dave, I don't think it's so much the straight difference of resting on the floor vs. resting on the base but, rather, when people rest XO boxes on the floor, they typically put some isolation material under the box.

I agree the thought that isolating passive XO components from vibration improves the sound is way out on left field but IMO the idea has validity, due to my own experiment.  And I suspect it's the caps which are the culprit (rather than the inductors).

I don't know if you're aware of the Vibraplane, which you can buy as a (very expensive!  ) vibration isolation base for components like TTs, CDPs, amps etc.  I read about them a few years ago and decided, just as a quick experiment, I would put squash balls under my amp/XO boxes (that sit right behind each Maggie), to provide a crude amount of isolation from the floor.  Seeing as the slab floor was being excited as a result of the spikes in the IIIa bases.

I was amazed to find the sound was "cleaned up" a bit - in a camera analogy, like someone had just twisted the lens slightly, to get everything in better focus.    I didn't believe my ears at first but then I invited a rew friends over, who knew the sound of my system and they commented similarly.  So isolation of components - amps, active XOs and even passive XO boxes - definitely has merit, IMO. 

I recommend you don't try the experiment, though, because I think you'd go crazy trying to think of what to measure, in this scenario, to provide solid measurements of the difference in sound when the XO box is isolated vs. when it isn't? 
 
Regards,

Andy