Magnepan 1.6 upgrades

geoff727

Hello all,

Here is a modification I just completed to a pair of Magnepan 1.6 speakers. The 1.6's were supplanted in Magnepan's line by the 1.7 this year. The 1.7 introduced the aluminum "quasi-ribbon" driver on the bass panel as well as the treble, and also included an outer q-r trace as a very high frequency driver, improving the high frequency dispersion over the 1.6. In essence, the 1.6 is a two-way speaker, the 1.7 is a 3-way speaker.

The first, and essential (at least I think so) mod is to replace the Magnepan stock feet with MyeStands from Grant VanderMye (http://www.myesound.com/). Some on this forum have used Grant's spikes, which are very nice.

Here's a couple comparison pics of the stock feet and what the MyeStands look like.

More to come.....

geoff727

The next thing to do was to improve the 'ruggedness' of the stock frame. A lot of folks have built custom wood frames for their Maggie's. I decided not to go that route, instead just concentrating on beefing up what was already there.

Here's what the Maggie looks like without the cloth. Look hard and you can see that the magnet/driver panel frame is held to the main frame by lots and lots of staples, inserted sideways. The flange on which the magnet/driver frame rests is only about a third of an inch deep.

I wanted to improve that, as well as make the speakers actively vertically bi-amped, which means removing the passive crossover.

On the "empty frames" photo, one is forwards, one is backwards. Note there is a large amount of 'unused space' between the edge of where the magnet frame goes and the main frame's rounded edges.

geoff727

To improve the rigidity of the main frames, on the backs I glued in long pieces of MDF to both sides, top, and bottom. These pieces had nicely rounded-over edges from router work. I also did a lot of filling (with a resin filler) and the requisite sanding and shaping to get everything looking smooth and coherent.

The space from which the passive crossover was removed was no longer necessary, so it required a lot of filling.

These pieces increased the depth of the magnet panel mounting flange from about one third inch, to about one inch (or so). A big increase in strength.

geoff727

I knew I didn't want to hold the magnet frame to the main frame with staples, so I cut a 4-piece retaining frame. Two sides, top, and bottom, with rounded-over inside edges. Once the magnet frame lays into the main panel, the retaining frame goes on top of that and holds the magnet frame in place, evenly across the whole panel.

Here are pictures of the retaining frame, and the main frame when it was cmpleted. I included vinyl damping layers, which go in front of and behind the magnet frame. 2 layers in front (on the retaining frame), 2 layers behind (on the main frame's mounting flange). The fit was not absolutely perfect (the damping vinyl was about 1/128 inch too thick), so I had to include a thin felt layer on the main frame to ensure that the "sandwich" was absolutely flat and accurate.

geoff727

Test fitting the reatining frame into the main frame.....

geoff727

And once the main frames were all refinished in black, smoothed, and cleaned, it was time to insert the magnet/driver panel, and sandwich it into place with the reataining frame.

Each retaining frame has 99 counter-sunk screw holes. When screwed down, each with a certain value of torque, the magnet/driver panel is held firmly in between the 4 vinyl damping layers.

geoff727

All those screws would, of course, be visible through the cloth "socks" that cover the speakers, so I finished off the retaining frames with felt. No more visible screws!

geoff727

Before the socks go on, the new binding post plates and hook-up wires need to be installed. I used the stock binding post plates, with an 'inner plate' that was CNC'd by Front Panel Express, here in Seattle. These folks always do nice work, I've shopped there a lot.

The original Maggie binding posts were replaced with Cardas CCGG's, the wiring is Neotech solid-core OCC w/ teflon insulation. I somewhat foolishly used a much larger gauge than what I really needed.

The original connection between the passive crossover and low & high panel wires was made with quick-disconnects. I did away with those and (thanks to McLendon's hardware in Seattle) pieced together some contraptions that served as very solid, tight compression fittings. The hook-up wires are connected to the panel's wiring by direct, strong contact under pressure. I didn't want to risk soldering, as the mylar which forms the driver panel (melting point around 300 degrees) is only an inch away from the hook-up junction.

Even the pressure fitting requires care. I made a 'snake' in the bass panel's wiring to distribute the pressure (visible in the photo). With thin wires like this, one can occasionally compress one's way right through a thin wire with enough pressure.

geoff727

Backing up just a bit, I did a test on both speakers for an hour or so, before completely **** down the retaining frames. This verified that the "all-active" system was working as planned.

geoff727

To finish, the socks go back on, get carefully tacked down, and the binding post plates get re-installed. Before re-installing the MyeStands, I decided to re-do the side trim in oak. I was never really crazy about the original dark trim (even though I did order it that way). I like the oak a little better, though. It defines the vertical line of the speaker better, and goes with the rest of my system better.

Here's the new oak trim, MyeStands re-installed, and everything hooked up.

geoff727

And finally, here they are on the system. The system is now fully active, with 6 channels of amplification.

Each Maggie gets it's own Odyssey Audio Khartago Stereo Extreme, with the McIntosh 6900 integrated doing pre-out duties only. Channel 1 of each Odyssey goes to a treble panel, Channel 2 goes to the bass panel. Each Rythmik F12SE sub has it's own internal amplifier. The crossover is made with a dbx 234XL. I'm using this until I fully tweak the crossover points. Then I will order the plug-in resistor cards for my Bryston 10B-LR's.

Here's some pics of the system as it is today. I was rather meticulous and methodical in speaker placement, and the resulting placement yielded a non-visually-symmetrical arrangement. I can't move the racks, because the amp's power cords aren't long enough. And, I just have 4 outlets to choose from (good audio doesn't come easy in a 1-bedroom apartment!). The subs ended up behind and offset from the main speakers, with some interesting cable runs resulting.

How does it perform? Well, I don't know how much can be attributed to speaker upgrades, how much can be attributed to rack upgrades, how much can be attrributed to component selection, and how much can be attributed to going to a fully-active system. The result, for me, is simply fantastic. I've had (and demo'd for a few other Polk fans) these speakers for over 2 years. Now, the system is vastly exceeding any previous level of performance, in all areas.

jimmydep

Very nice well thought out mod......I'd love to have a pair of Maggie's some day.

Excellent job!!!


Jim

Ricardo

Wow. you went through a lot of work there. Nice job.

You could have replaced the MDF with wood with just a little more work. It does not need to look fancy, you could do it with the same dimensions and still use the socks if you want.
The benefit? MDF rejects vibrations and send them back to the panel. Wood absorbs vibration and dissipates as heat. Or so I've heard. But the truth is that it does wonders for the sound. You should try it.

dorokusai

Great post. I've used Grant's stands for years.

Toolfan66

WOW!!! Beautiful job..

george daniel

wow, very nice work indeed sir,,appears that you have devoted alot of time and effort into that rig.Thanks for posting your upgrade pics too.I really enjoyed reading(and seeing) the step by step upgrades.

disneyjoe7

Very nice upgrade beautiful.

AudioGenics

excellent workmanship and detail

geoff727

Ricardo wrote: »

You could have replaced the MDF with wood with just a little more work. It does not need to look fancy, you could do it with the same dimensions and still use the socks if you want.
The benefit? MDF rejects vibrations and send them back to the panel. Wood absorbs vibration and dissipates as heat. Or so I've heard. But the truth is that it does wonders for the sound. You should try it.

Hmmm. Now we could have an interesting conversation on this. Do you have a reference for the 'vibration rejection' qualities of MDF. That is something I haven't heard before; I'd like to read it.

When I decided to use MDF, I decided based on simplicity of construction, cost of construction, and a basic comparison of material properties. With large open baffle panels like this, flexural and vibrational modes are always a relevant consideration. In a source that I routinely draw from in making 'modification decisions', it talks about the flexural and vibrational Q's of quite a few construction materials, including MDF and different types of wood. And also, the basic resonant properties and Young's Modulus of each are compared.

Without getting too much into it, if I had to make the decision regardless of cost, I would probably make the frames out of something like this:

First choice: diamond
Second choice: Aircraft grade aluminum.
Third choice: Some types of tempered and laminated glass

This obviously gets to a point that's somewhat ridiculous. So, when I decide on what to do, I always approach it with a cost:performance consideration, and also on a basis of 'sticking with a known quantity'. For example, what will be the specific change in flexural Q of a given plank size of oak that is ripped vs. cross cut? All I know is that there will be a change, but without specific info on it, it's tough to make a decision based on that. Baltic birch plywood will obviously be a much more consistent material, and MDF is a very consistent material.

In the end my thought train goes something like this:
Ease of construction + cost + known material qualities + other construction considerations (size, weight, damping used, etc.) - material quality unknowns - time I want to take to do this = decision.

Anyway, if you have a reference for that, I'd like to se it. Thanks
G~

kcoc321

So that is what you have been so diligently working on... Looks like quite the improvement and a great write up as well. I would think the 'clamp' system vs the staples would be an upgrade that Magnepan should do.

I can't wait to hear them, as well as the 'new' amps

geoff727

dorokusai wrote: »

Great post. I've used Grant's stands for years.

Thanks. I forgot to mention, the struts of the MyeStands are sand filled. Have you tried this?

geoff727

kcoc321 wrote: »

I would think the 'clamp' system vs the staples would be an upgrade that Magnepan should do.

I don't disagree. But, the reality is, if they did something like that then the retail price would jump by at least several hundred dollars because of the labor involved. Maybe a thousand dollars. Who knows. And one of the things I like about Magnepan is that the cost is kept within the means of a lot of audiophiles like myself.

The cost of the 1.7 is the same retail as these were, with better stock performance. And decisions like that will probably see the company through these hard economic times.

I think you will like them. I hope. I wouldn't want you to think poorly of me.

Ricardo

geoff727 wrote: »

Do you have a reference for the 'vibration rejection' qualities of MDF. That is something I haven't heard before; I'd like to read it.

Let me start by pointing out I followed my statement with "Or so I've heard"
I do not have any reference to this other than what I read in Peter Gunn's site. I know. He makes a living from selling these wood frames. But I have confirmed that the improvement his mods produce is impressive. How much comes from the wood frame and how much from the xover? No idea.

Anyway, here it is:

http://www.indiespinzone.com/mag/mag4.html

"Magnepan speakers in stock form have a few issues, but they have one major problem. Vibration. It is the biggest source of sound degradation maggies have. If you observe a pair of maggies playing moderately loudly with their socks off you will see more vibrating on the driver than you would have imagined, and in fact some people manage to get theirs to make a "slapping" noise. (from the mylar actually striking the magnets, the culprit here almost always being an underpowered amp) Maggies make sound by vibrating the mylar, but once made, ideally we'd like those waves to vanish and not interfere with the next ones. However the maggie driver is attached to an MDF frame which does not accept any of this energy. In fact, because of MDF's normal refusal to accept vibrational energy a large portion of it has no choice but to return to the driver from where it came where it meets and destroys those new waves being formed, with the net result being major loss of detail and smear.

Sadly, for many years people misunderstood why this smear happened and they incorrectly assumed the problem was that the speakers were moving or shaking. They tried to solve this non existant problem by "stiffening" the panels with struts and metal frames. Since adding these things had some effect on the sound, people felt vindicated doing it, and it became the accepted truth. Yes, attaching struts to stock maggies will yield some improvement, but not for the reason thought. To add a strut you also need to add a base, and all three, speaker, struts and base come together in a triangle. This triangle naturally provides more floor coupling which allows more of the vibrational energy to bleed off into the floor than would normally escape the frame. However only a smaller amount more is getting off and they are not solving the inherent problem because "stiffness" isn't the actual problem.

We know that the real problem lies in the fact that the MDF frame refuses to take up and diffuse the vibrations the maggie driver makes. Imagine the maggie driver as a body of water and the waves generated stemming from a rock thrown into it's center. This first wave set is beautiful and very clear and distinct. However when it reaches the shore line it has no where else to go, whereupon it rebounds back in the direction it came from. When this wave front collides with the next set of waves it makes "choppy water" which is no longer clear or beautiful and that is exactly what a maggie driver in MDF looks like when playing and sounds like when playing - Choppy Water. The solution therefore is to remove these waves entirely and stiffening will not do that.

---

Fortunately it turns out that there is an ideal medium which can do this: Wood. It has a natural ability to absorb vibrational energy and diffuse it. In fact, that is one of the main jobs it is designed to do. It's cell structure is compliant and this shifting ability of it's cells allows it to turn vibrational energy into heat (friction) and dissipate it. An interesting thing I discovered is if you hold a stock maggie by the MDF frame while playing, you really don't feel a lot of vibration, but if you look at the driver it will be bouncing all over the place. If you hold one of my frames while playing the amount of vibrational energy one can feel is startling, however if you look at the driver, no movement can be seen, even at high volumes. The sound you'll hear proves I am correct, and the fact that my frames move and vibrate so much while doing this disproves the "stiffening" argument as well.

Magnestand frames accept the wave energy reaching it, turn it into heat thru cell friction and simply bleed it off, therefore it NEVER comes back into the driver and that energy never contaminates the subsequent waves. What you get is one of the purest sounds in audio, which has been compared to and even beaten electrostats in its delicacy and beauty.

We do still use struts in the design because they add to the over all strength, but I have played modded maggies without them installed and I have yet to be able to say I can tell a difference. That's because the wood frame is doing the job so well, there is nothing left for them to really do as far as draining away wave energy and "stiffening" as we've proven is not a real issue. "

dorokusai

geoff727 wrote: »

Thanks. I forgot to mention, the struts of the MyeStands are sand filled. Have you tried this?

Yes, I use shot.

geoff727

Ricardo wrote: »

Let me start by pointing out I followed my statement with "Or so I've heard"
I do not have any reference to this other than what I read in Peter Gunn's site. I know. He makes a living from selling these wood frames. But I have confirmed that the improvement his mods produce is impressive. How much comes from the wood frame and how much from the xover? No idea.
[/I]

Thanks. I thought a lot about doing Peter Gunn's upgrade. He definitely does beautiful, inspiring work on these. The woodwork is exquisitely attractive.

I have read this before, and will do so again. It would be interesting to do a direct comparison between different frame improvement methods on these and hear exactly what does what. I should note that, the driver panel frames now have 4-layer constrained damping, 2 on each on each side of the panel. This was to counter what I think is the exact thing you're talking about.

In the end, I'd be willing to bet that, like all things audio, the "improvement" would be a matter of personal subjectivity.

G~

geoff727

Some more brief notes on the speakers...

I owe a big thanks to my stepdad, who provides shop tools and a lot of help and time. And my mother, who tolerates her garage being dustied and cluttered up for projects like this.

Crossover points are 50Hz and 600Hz. This may be slightly tweaked. All frequencies below the low-pass crossover are sent to the subs. This has the advantage of the Maggie bass panels not having to worry about reproducing frequencies that generate a lot of panel excursion, but that are reduced in amplitude because of dipole cancellation. I hope this results in less fatigue on the bass panel over time.

It also confers a slight advantage in amplification, as a bit of extra headroom is preserved (the Odyssey's don't have to worry about reproducing those frequencies, either). Since those frequencies are sent to the subs' amps, it moves the "equal power split" (usually around 300-350 Hz) a bit higher, which is where the crossover is taking place by virtue of design of the speakers. Nice and convenient!

Ricardo, have you heard any 'Gunned' Maggie's? I never have had the chance.