[Voncarlos]

I am starting to make wood frames for my  Magnepan MGIIIa's.
I'm wondering what the general consensus has become on these, now that enough time has elapsed when this was such a topic 5 years ago.
I have read many past posts here on Audiocircle and on several other forums and websites.
Now that time has past, what are the thoughts from folks that have done this?
Pluses and minuses or mistakes?

I have some walnut wood flooring pieces left over and will machine these up to use.

[Roger Gustavsson]

I do not think there is a consensus on this matter. I have not seen any vibrational analysis on different types of baffles/frames. An easy way is to use a tuning fork and hold it to the baffle/frame. Wood, particle board, platsics, concrete, metal, laminations of various materials, they all have their properties. Personally, I am against a single solid type of material. I prefer to mix materials with different properties. The way the baffle/frame of Magnepan speakers is made, it is very flimsy. Are we sure that the flimsiness is all bad? Is the opposite what we want? What will sturdiness do? If we want to absorb energy, what materials will do that? Hard and sturdy? To me, a hard and solid material will not absorb very much. It will probably have a high transfer speed of vibrations but it will not absorb them much. Is not high absorption  = high loss of energy? 

[Davey]

The consensus is that there is no consensus.  There isn't even a consensus on what the objective is for wood frame retrofits.    Is it aesthetics?  Acoustics?  A combination of both?

Roger brings up the appropriate (and excellent) questions, but I've found that the answers are not really of interest to the majority of Magnepan users. 

One thing we do know......is that WAY more Magnepan's are successfully in service with stock MDF frames than with modified frames. 

If you have some leftover wood and need a project, by all means construct some wood frames.  I guarantee they'll sound different than stock.

Cheers,

Dave.

[andyr]

Sorry, Voncarlos, I'm late into this thread.

As others have said, there's not really a "consensus" about whether this is a "good thing" ... or not.  However, if you search the Planar Asylum archives, you'll find many posts by people who have gone to the trouble of either making, or getting made up, hardwood frames.  Possibly Davey is the only one who posted that he didn't get a sonic improvement.

I had some hardwood frames built for my IIIas and heard a substantial increase in dynamics - despite them already being in braced stands.  I then had the same guy build hardwood frames for my current Maggies.  While Davey makes a true statement that there are many more people whose Maggies have stock MDF frames than there are those with custom-built hardwood frames ... to my way of thinking, this is a pointless justification for not going ahead with hardwood frames.  If I can put forward an automotive example ... the vast majority of Mercedes customers buy the stock models; only a very small percentage bother with the AMG versions.  I know which I would want, were I in a position to buy a Merc! 

And Roger's comment that maybe the flimsiness of the stock MDF frame is a good thing is bizarre.  If flimsiness was a good thing then everyone who puts their Maggies into (braced) Mye stands would hear a downgrade in SQ - which is not the case.  Magnepan build them the way they do because any alternative framing solution would not enable them to keep in business.  As someone pointed out on the Planar Asylum, the equipment costs and the wood-stock costs of getting into hardwood frames is simply enormous - and cannot be justified.

So, as someone has had hardwood frames built for my Maggies (twice), I would say go for it!    If you have the timber, the tools and the competence to do the work yourself then you have nothing to lose.

One point that I would like to mention that's associated with hardwood frames - and contributes some of the benefit in dynamics that I noticed - is the method of fixing the driver to the frame.  Magnepan's use of staples is cheap - and does the job.  However, it doesn't anchor the driver to the frame as firmly as screws will, with a hardwood frame.  I can vouch for that because when my IIIas had stock MDF frames, I replaced the "staple fixing" method with some clamps made of mild steel lengths having an 'L' cross-section.  The long arm of the 'L' lay against the back of the MDF frame (with bolts through the MDF) while the short arm pressed against the pole piece (I had my mylar at the front).  This meant:
a) the driver was firmly clamped to the frame, and
b) the lengths of bolted metal 'Ls' stiffened up the MDF frame.

The result, as I said, was an amazing increase in dynamics - which was remarked upon by a friend of mine who has never liked Maggies, for the reason of lack of dynamics, compared to cone speakers ... who said he had "never heard Maggies as good-sounding as that"!  When I then moved to hardwood frames, they sounded even better!

In terms of suggestions for your build:

1. Use 1" hardwood if you can - but if your flooring pieces are only 3/4" thick, that will be fine.

2. While it's easier to build a copy of the MDF frame in hardwood, there is a worthwhile gain in SQ by putting the ribbon cage in a separate frame.  This stops vibration produced by the bass panel from shaking the ribbon cage.  (In my case, I have one frame containing a T-IVa mid panel and the ribbon, and a 2nd frame for the bass panel.)  This also allows you to angle the ribbons more than bass/mid panel and also to move it either forwards or backwards (depending on whether you have ribbon out or ribbons in) to time-align the drivers - impossible when they are all in the one frame.  The only difficultly you might have with only the ribbon cage in the (narrow) frame is keeping it stable - I did this by mounting the frame at the front edge of a wooden base, 2' long and making the back of this base much wider than the front.  There is a brace which attaches to the back of the frame and the back of the wooden base. I can send you some pics of my setup, if you PM me your email address.

3. If you don't want to drill through the driver surrounds, to make the holes to screw them to the frame, you can instead used a clamping arrangement like I did with my IIIas.  However, if you do drill holes in the driver surrounds, cover both sides of the driver itself with paper taped to the frame, first ... so the drilling scarf doesn't get onto either the mylar or the (magnetic) pole piece.


Good luck,

Andy

[Davey]

I get irritated when people put words in my mouth........especially when they're words I didn't say. 
If you search back you'll find that I didn't indicate either way if I thought the frames brought a sonic improvement.  I had a reason for not stating my opinion on the matter.....which I related at the time.  I guess you forgot that too.

You might also want to review the design I undertook for the MMG frames.  It was quite a bit different than the Magnestand scheme.

That said, other than the cost and all the work, there's not a downside to re-framing the speakers.  It's worth doing.......if you do it right.

My goodness.

Dave.

[andyr]

Hi Davey,

I'm not trying to start a war here - simply that, whereas I have stated many time that I think hardwood frames produce a definite benefit ... every time I've seen you comment on wood frames vs. MDF, I've never seen you make an explicit statement supporting the concept of hardwood frames.  So if you don't promote them ... you must think they are not a good idea! 

Now, there could be several reasons why your - poplar, weren't they? - frames were not an unequivocal success.  Whatever they might be, the way I see it stacking up is as follows:
* the overwhelming majority of Maggie owners - as you pointed out - wouldn't contemplate hardwood frames.
* the small percentage who have tried hardwood frames are all in favour ...
* except for one - you.     And possibly Roger - I can't make out whether he has tried hardwood frames or not.


Regards,

Andy

[Davey]

Hi Davey,

I'm not trying to start a war here -

You're doing a pretty good job of it.

The speculation and conclusions based on things I didn't say is.....pathetic.

How 'bout you let me speak for myself regarding my framing project and my evaluation of it?  Is that too much to ask?

Dave.

[andyr]

Well, as the OP posted here to get comments from people who had tried hardwood frames instead of MDF, that would be a great idea, Davey. 

To try to help the OP, I've posted my experiences - in some detail; I'm sure he would be interested in hearing about yours.  If you can't be bothered typing it all in again, you could always direct him to your long-ago PA post.


Regards,

Andy

[Davey]

My opinion is the reframing is worth doing....but only if you implement with a "sandwich" construction as I did.  This allows to not drill holes in the transducer frame....no mechanical fasteners are required.....and a much more even contact pressure on the full perimeter (both sides) of the transducer is provided.  It does require double the amount of wood and fabricating "spacer" strips with a fairly defined thickness so you get adequate contact pressure but still allow movement.  It also looks good from both sides.
Those are just a couple of the advantages.

I have some accelerometer testing plots of frame vibrations relative to the stock frame that show not insignificant differences.....as you would expect.
The type of vibrations created are primarily high-frequency in nature and look horrible relative to traditional accelerometer measurements evaluating cabinet panel vibrations in conventional speakers.  However, conveniently, these vibrations are also dipole in nature.  It's an interesting effect.

The re-framing concept is sound.  I first saw this employed on a set of Magnepan's about 25 years ago.  I don't remember for sure, but I think it was a set of IIb's.  The fellow employed a rabbeted construction technique from one-piece rails of 5/4 oak material.  They were actually quite beautiful.

In spite of the seemingly common belief.....John did not come up with this idea......and neither did I.  And Jim Winey was well aware of this construction approach and the advantages/disadvantages many years ago.

I think we badmouth Magnepan too much for their engineering decisions.  Engineering is all about trade-offs and their decision to utilize MDF construction and the simple assembly technique is easily understandable in my mind.

I don't mind being insulted for my objectivist approach to all things Magnepan, but I what I don't appreciate is my words/statements being mischaracterized/misquoted.  That happens far too much in the MUG community.  Others have experienced this as well and it's very disappointing.

Cheers,
 
Dave.

[andyr]

Great post, Dave - which I'm sure will be really helpful to the OP.


Regards,

Andy

[Roger Gustavsson]

My opinion is the reframing is worth doing....but only if you implement with a "sandwich" construction as I did.  This allows to not drill holes in the transducer frame....no mechanical fasteners are required.....and a much more even contact pressure on the full perimeter (both sides) of the transducer is provided.  It does require double the amount of wood and fabricating "spacer" strips with a fairly defined thickness so you get adequate contact pressure but still allow movement.  It also looks good from both sides.
Those are just a couple of the advantages.

I have some accelerometer testing plots of frame vibrations relative to the stock frame that show not insignificant differences.....as you would expect.
The type of vibrations created are primarily high-frequency in nature and look horrible relative to traditional accelerometer measurements evaluating cabinet panel vibrations in conventional speakers.  However, conveniently, these vibrations are also dipole in nature.  It's an interesting effect.

The re-framing concept is sound.  I first saw this employed on a set of Magnepan's about 25 years ago.  I don't remember for sure, but I think it was a set of IIb's.  The fellow employed a rabbeted construction technique from one-piece rails of 5/4 oak material.  They were actually quite beautiful.

In spite of the seemingly common belief.....John did not come up with this idea......and neither did I.  And Jim Winey was well aware of this construction approach and the advantages/disadvantages many years ago.

I think we badmouth Magnepan too much for their engineering decisions.  Engineering is all about trade-offs and their decision to utilize MDF construction and the simple assembly technique is easily understandable in my mind.

I don't mind being insulted for my objectivist approach to all things Magnepan, but I what I don't appreciate is my words/statements being mischaracterized/misquoted.  That happens far too much in the MUG community.  Others have experienced this as well and it's very disappointing.

Cheers,
 
Dave.

Interesting! At least someone who has measured the vibrations of the frame.  Why do some believe that strongly in that hardwood acts as a vibrational sink? How do we normally sink or kill vibrations? How do you define hardwood?
 
I think there  is a lot on a coupling between what we see (aesthetics) and what we hear. If it looks good it really sounds better! There is also a feel good factor, if it feels solid, it make us think it is better.
 
As in many cases of audio modification, there is a risk that the person behind these hear things that others wont. There is always a strong link between knowing what has been done and what we expect to hear. If you have ever been taking part in a double blind listening test or even just a blind listening test, you know what I mean... There have been tests where the only difference between to preamps were the volume knobs, one had a more massive one. In sighted test everyone heard clear differencies. In a double blind listening test, no one was able to hear a difference.

[Davey]

Yep, there is certainly an aesthetic factor to the reframing project.  The audiophile brain usually hears what it wants to hear and makes solid conclusions from said subjective evaluation.    If your eyes can hear it too.....so much the better. 

I approach everything from an objective and engineering standpoint and attempt to highlight the nonsense that is promulgated from far too many.  That's why I rarely relate my own subjective evaluations on equipment or projects that I'm working on.

The "vibrational sink" aspect is the primary underlying claim to this modification.  If we believe that is a valid engineering objective then the follow-on work is obviously to identify better materials or contact schemes to provide that 'path'......and hopefully do it in a fairly inexpensive way and one that the average handy person can implement.

Dave.

[andyr]

The "vibrational sink" aspect is the primary underlying claim to this modification.

Dave.

As I see it, the "vibrational sink" was one man's attempt at explaining why hardwood frames improved the sound.  However, so many other people had made the switch (to hardwood frames) and liked the result - so that was good enough for me to go down that route.  Philosophical musings as to why ... I leave to others. 

Andy

[kappa546]

Davey, do you you have pictures or link to a page that shows your reframing project?

[Davey]

Well, it's been a number of years now, but try this:
http://home.comcast.net/~dreite/MMGframe.htm
I have ton's of MMG photo's/information, but those outline/highlight the process fairly well.

Dave.

[Roger Gustavsson]

Thank you Dave!

[Voncarlos]

Thanks for the replies and the suggestions.
I have followed along with the re-framing ideas and post for about 5 years now, so I am already familiar with many of the folks here and their ideas.
I think the idea of using the Kreg jig and sandwiching the panel is brilliant!
I bought one of the Kreg pocket-hole jigs several years ago to make some cabinet face-frames, but sadly it doesn't get used much these days.

I have a few pics and thoughts:

Here is the progress of the base frame.


And my rough Sketch-up.


And a crazy idea I played with.


After I removed the grill-cloth from the IIIa's and began to look closely at the various construction techniques, I noticed that there were no fastening points at the bottom and top.
At first I thought, "oh that's not very good," but then I saw that the panel is actually curved.
I don't know if this is designed this way or a deform that has developed over the past 30 years of living in different relative humidity.
It's a good way to ad some strength to the panel, and I've also read that it's used to prevent the panel from slapping. 
No matter, I've got to accommodate for this.


I also noticed that Magnepan added a little bulk to the area where the panel rests under the staples.


I am wondering why these router cut-out were applied.
They are at the top and bottom of the ribbon.

[Davey]

I hope everyone appreciates the design of that "sandwich" construction.  The objective is to yield even contact on the total perimeter of the transducer unit, but not have a death grip on it.  It needs to be able to "float" within the sandwich.  The first two MUG users who attempted to duplicate my scheme completely misunderstood the concept. 

The transducer contact area should have the black paint sanded to generally smooth it and also remove any paint ridges from the initial painting at the Magnepan factory.

The pocket screw joinery works fine and is very easy to implement.  My speaker reframing was completed in 2009 and the integrity of the transducers and frames are still perfect.

The bend in the transducer units is normal and should not be "straightened out."

Dave.

[Voncarlos]

The objective is to yield even contact on the total perimeter of the transducer unit, but not have a death grip on it.  It needs to be able to "float" within the sandwich. 
Dave.

Hi Dave, thanks.
I am afraid I don't understand your terminology or maybe your concept.
The term "float" would have one thinking that the panel should be able to rattle around in it's constants.

I think the panel needs to be held firmly in place along its vertical edges but not "death gripped" to the point of deformation.
While at the same time allowing for expansion and contraction of the various component properties.
Something similar to a slip-grip.
I was thinking of adding some Teflon tape to the areas of contact to allow for slip.
And I'm working on using a wedge to make the "grip." This would allow me to adjust the tension over time.

I should also add that Magnepans solution to this is very good considering their cost constraints.

Anyways, with the way this thread has gone at times, I want you to know I'm not picking on you, I just want to clearly understand.
Thanks, 

[Davey]

It sounds like you understand the terminology and concept just fine. 

Yes, the panel should not rattle around within the sandwich, but it should be held securely enough to allow wood changes with temperature/humidity to not exert problematic forces on the transducer unit.

I think your idea of using Teflon tape is probably an excellent one.  I think I would apply the tape to the transducer unit and not the wood pieces.
Regardless, the critical part of the project is the spacer strips that create the proper gap in the sandwich.  Those should be almost the exact thickness of the transducer units.

Cheers,

Dave.