Magnepan/ESL combo

[SM7UYJ]

Hi,

I'm planing a new winter project and would like your input!

I receantly got hold off two pairs off old Magnepan MG2 who need to be rebuilt as the coils have become lose from the membrane.
The plan is to rebuild one pair and use this as a pure basspanel in combo with a electrostatic mid/high-panel.

Now to my questions:

How would you build the mid/high section?
I have tools to cut sheet metal but max 10000mm long => one 1m section or two 7-800mm, but at what width?

Should I have the Magnepans and the stats in separate frames or build a combined one?

/R

 

[SM7UYJ]

No one

XO will be 100-200Hz.

/R

 

[DaveG]

Having MG1-A improved (similar to the MG 2 I believe) and also Acoustat 1+1's, I’ll make some comments on this.
First - I believe the full range Acoustat’s at 9” x 94” panel area have better bass than the 1A’s. Neither are perfect.
1A’s may have more apparent dynamic sound and maybe sound more like a very, very clean cone woofers than the electrostats, but the Acoustat’s are somehow more open and detailed.

The “sound” of the two panel type is different. I’m not sure they will smoothly blend together. These comments are based on my using the exact same CD player and amps. The two speakers present different/difficult loads and neither of my amps, one tube, one SS, is well suited for either of these speakers, and that may have contributed to the different flavor of sound. That is why I now use direct drive amps for the Acoustats.

To me, although the Acoustat bass is far from perfect, the seamless crossoverless quality of the lower mid/mid bass/upper bass region is a great benefit.

I once started panels using the Sanders method of sheet metal and plexi glass and never completed the project. On the long project list is to try building improved Acoustat style panels, using the light louver/wire method and I would use the wire spacing and stator/mylar dimensions and mylar gauge information from a great thread here on DIY about building Acoustat style panels.

Myself, I would build Acoustat style panels, tall and skinny, and maybe try your MG 2’s as woofers/subwoofers at a lower frequency, 100 hz or 70 hz. If you incorporate the MG 2 panels into the electrostat frames you will not have any other options to reconfigure. (well, maybe you could fill the space with more electrostatic element if you did not like it)
Keeping the 2 speaker panels separate also has it’s problems. I once set up Acoustat Model 3’s (25” x 42” panel size) as subwoofers to the Model 1+1’s. The bass was better but because of different signal path lengths it created an slight artificial reverb effect. The large Model 3’s panels could not be placed close to the main full range panels without fouling up the imaging. A future project (another on the long list) is to build a crossover with some phase/delay adjustment.

Dave

 

[SM7UYJ]

Hi Dave,

Thanks for your reply!
I have a friend who has a pair off rebuilt MG2's that play well in the lower region but to my liking, lacks in the highs.
In my DIY ESLs its just the highs that I find the best, so I taught I'll combine the two for a complete plannar setup (my ESLs are hybrids with a 12" woofer). The plan is to use active filters and separate amps to make integration "easier"!
Have you measured your Acustats? It would be interesting to know how low they play in room conditions!

/R

 

[DaveG]

Hello /R,

No, never measured, but Acoustat’s go quite low, 35-40 hz. As a reference point, the “heartbeat” on Dark Side of the Moon is very nice. Not as solid as 10 inch woofers in full transmission lines, but there is a solid feeling of the heartbeat.

I have heard better bass. But the seamless blend is always a problem for me, and for now, I have compromised on the low bass quality in exchange for the seamless blend to the mid bass/ upper bass/low midrange. And yes-I agree that the mid/highs of the electrostatics is great.

You got me thinking about the Magnaplanars today. I have never heard them with a really good high current amp. The slightly more dynamic quality they have, more impact, may be just what is needed for a good low end. You may be onto a good combination.

What do you do now for EQ and crossover point to the woofer? How low do do your panels go?

I have a Panasonic mic capsule and DB meter and signal generator. All manual, no software. Can I perform a near field measurement, just like a standard woofer, with an open electrostat?

Dave

 

[SM7UYJ]

Dave,

Right now I'm using a passive 12dB XO at 200Hz in the speakers, and dipole compensate up to 100Hz with a active filter in my preamp.

My ESL-panels f0 is abt 50Hz:

(Measured with Tombstone and a DIY-mic and DIY mic-amp)

Measurement off flat ESL panels is not the easiest, specially in the higher regions, but it shows you if your in the ball park or not!

My aim is to cross over as low as possible, but due to space considerations in my listening room, I think a 200mm wide ESL-panels is the limit my better half will accept!

With a 2mm d/s perhaps 200Hz XO is a bit optimistic?

/Roger

 

[DaveG]

Plot looks good. How wide and tall are the panels that you used for the measurement plot?

I can’t comment on the d/s spacing. Others here with a lot more building experience for that.
Are you crossing over at 200 hz to keep away from the panel resonance?
200mm width should image good. That is a bit narrower than I listen to now. How tall can you go?

But to get back to your original question of separate or combined frames - I myself like the idea of separate frames, like the old sub/satelite idea. Narrow panels image the best. Wide panels have best bass. How can one frame meet both requirements? Maybe a large tall triangle like Apogee ribbons? Maybe the Magnaplanar panels can go under the electrostats? But making it look nice may be a challenge.

I guess a lot is going to also depend on your room requirements.

Dave

 

[NewVista]

I will be trying this very thing shortly: ESL surround w/ Mag MG-1 bass panels running in infinite baffle (just found a pair of MG-1 with open circuit tweeter wires - made from fragile aluminum wire, these are often found open). But I don't care, just want 'em for the bass.
Current system has inf baffle Altec 416 horn.

 

[SM7UYJ]

I finaly got my pair off MG-IIs!

Two off the panels can be saved by rewiering the tweeter section.

And two will need to be redone compleatly with new Mylar and wire.

(one panel toataly stripped)

I have 3µm, 4.8µm and 12µm Mylar at home. Fist taught was to use the 4.8µm one, but now thinking if it's not good enough with the 12µm one?

The wire and glue weigh alot compared to the film, and the 12µm film should be easier to work with in this case.

/Roger

 

[SM7UYJ]

I stripped the tweeter section again last night...

....and rewired using 0.2mm wire.

The resistance now went down to 6.4 Ohm -alot better!

I'll try to sweep the panels in the next few days to see how well they preform!

/R

 

[DaveG]

Hi Roger - any thoughts yet on how you are going to configure the bass panels with the stat panels?
Dave

 

[kavermei]

Hi,

with this combination ESL+Magneplanar you probably have a lot more freedom in choosing the crossover point than you would in case of a ESL+dynamic woofer. Perhaps a smallish ESL panel would be quite enough -- basically taking over the function of the Magneplanar's tweeter section? Just a thought...

Kenneth

 

[SM7UYJ]

Right now I'm repairing the pair of MG-IIs that are in best condition as a "slow start" to get som feel for how to rewire.
Most likely I'll use the other pair with 5µm film and wire the whole panel as a bass panel.

Kenneth: You are probably right and a small panel makes everything so much easier - less d/s - less EHT - small audio transformer e.t.c.

I have some 1000mm stators that I can cut to 50-80mm wide strips and give it a try!

/Roger

 

[kavermei]

Sounds like a plan! I'm very curious, if the two panels will 'blend' well. I guess there's no reason why not.

 

[SM7UYJ]

Did the other panel the other night, but tried aluminum foil - works great!

No fuzz with glue - just clean the Mylar and tape the foil on the film.
A bit tricky doing the turns but I have used this foil in my ESL-speakers EHT-loops so I know how to fold it!

With a 9m long 1.5mm wide strip, I now have a 4.5 Ohm coil so I'll have to adjust the cap in the XO.

I think it sounds better than the one with the Cu-thread, but I'll do some measurments to verify.

Any one know off a good trick to solder the aluminum foil?

I've got it to stick to the binding posts using the old solder that was already on them, but would like to ad some new fresh solder as well!

/Roger

 

[chinsettawong]

Nice!

Wachara C.

 

[SM7UYJ]

"Any one know off a good trick to solder the aluminum foil?"

I found a tip on using WD-40 as fluss/air block - will give it a try!

/Roger

 

[kavermei]

Soldering aluminium is a pain in the as^2. The problem with raw Al is the extremely hard layer of alumina which forms within seconds of air contact. I done it a few times but never found an easy, reliable way. Best bet is to mechanically remove the alumina layer (e.g., by sanding) immediately before soldering, and using an acid-based flux if you can find one. Alternatively, wipe the aluminium with sulfuric acid (from hardware store or pharmacy) to dissolve the alumina. (Wear safety goggles)

Good luck!

Edit: apparently, WD-40 contains nitric acid, so yes, that could work too.

 

[john65b]

I have rewired many Magnepans, and for tweeter section rewires, I just used Copper Magnet wire from Radio Shack. Worked perfectly. Originals are aluminum, but the Copper may be a bit of an improvement if you ask me.

I have never re-Mylar'ed a panel, tho. I always got hung up on how to best tension the Mylar for proper tuning.

BTW - If anyone has ever heard bass on Magnepan Tympani Bass Panels with Icepower 1000ASP modules, it is nothing short of awesome.

 

[NewVista]

I have rewired many Magnepans, and for tweeter section rewires, I just used Copper Magnet wire from Radio Shack.

That's what I was going to try with mine , simple enameled copper. What gage ? & what resistance did you achieve ?