[djcxxx]

The ribbon is delicate. Without the magnetic strip in place, just putting the speaker back in the box can cause it to rupture. Mishandling the speaker may cause more warranty claims than actually "blowing out" the ribbon by overdriving, particularly if the fuses are left in place. 

[josh358]

Josh,

Re:  Trip to Magnepan - Sweet!  I wasn't into high end audio in my college days when I lived in the Twin Cities area 30 some years ago.  I did visit Van Alstines stereo shop back then.  My buck list is full of modest goals, one of them being taking a trip back and visting Magnepan and Audio Research, along with an old friend or two.

P.S. - Try get a picture of you and Wendell standing next to x.7 circuit diagrams...

Regards,

Steve

Heh. "Oh, Wendell -- would you try standing over there where the light is better? That's right, next to the CAD monitor, the one with the sign that says "company secrets, keep away!"

[josh358]

Josh:

That what I first posted, again, in less technical terms. However, I still have an inkling that they feel that there is a loss of revenue due to repairs under factory warranty.  Having worked for the man so to speak and been involved in the executive process, if there was a concern over undue repairs and the simple solution was to eliminate the source, e.g., bi or tri-amping, and it wouldn't alienate but a rather small segment of their customer base, so be it.  Business is rather black and white, more so in times of financial turbulence. 

The mere fact that they do need to bold print that Ribbon Ruptures are not covered is a good indication that there is concern in this arena.  While they can't do a thing about under or over amplification from a single source, they can from bi or tri-amping.

Understand, the true die hard's who want to bi or tri-amp still will, but without the benefit of the 3 year limited warranty.

The only other alternative is that Magnepan feels that the employed x/o is superior and the end result of tone/resolution/clarity/dynamics justifies the end.  I will let the reader choose which option is best as there is no way a company will come out and say they did it to cut down on warranty repairs.  However, Wendell is known to be pretty straight forward and might spill the beans if under the influence of Josh's charm and with a dose of good music

Jim

Check this 3.6 schematic, though. They appear to have idiot proofed it, so that even if you tri-amp, the connection is ahead of the tweeter crossover components:

http://www.integracoustics.com/MUG/MUG/tweaks/mag3.6xover.jpg

The 20.1 is similar:

http://www.integracoustics.com/MUG/MUG/tweaks/mg20,1xo.gif

Of course, you could always bypass the filters by wiring directly to the tweeter terminals, but you can do that with any model if you're feeling suicidal.

[Robin Hood]

Does anyone know about the XO in the DWM? I believe the DWM woofer is stated as being flat from 40 Hz to 1500 Hz, yet the internal XO is set to approx 300 Hz.

The Magnepan website states: "The DWM and DW 1 were designed for use with any of the "small" Maggies, such as the motorized MMC 2 on-wall speakers, MC 1 on-wall speakers, desktop Mini Maggies or for bass augmentation of any of the Magneplanar center channel speakers. In addition, the Maggie Woofers can be used for fine-tuning the bass and midbass performance of floor-standing models.

Multiple subwoofers are commonly used to smooth room bass response. Although an expensive solution, this technique has been proven to be superior to EQ of a single subwoofer. Using the same fundamentals of acoustics, Magnepan has a solution which can fine-tune the bass and midbass of Magneplanar floor-standing models--- the Maggie Woofer (DWM and DW 1). When both time domain and frequency response has been optimized in a given room, smaller, floor-standing Maggies can begin to replicate the "Gold Standard" of bass reproduction--the Tympani series Magneplanars."

I would think you may want a different XO point if you are using a DWM woofer or woofers with any of the Magnepan speakers. I assume that requires disabling the internal XO, voiding the warranty of the DWM and using an external XO.

So someone with 3.7 Maggies who wants better bass using multiple DWM woofers would run both the 3.7 and DWM full range within the limits of the respective internal crossovers. But would you still want to run the DWM woofers up to 300 Hz, instead of say 200 Hz? And why would you assume that the crossover point is the same for the 1.7, 12, or MMGs.

[josh358]

AFAIK, they run them full range when they use them to augment the woofer panel area of the floor standing speakers. The Mini Maggies are fed off their internal crossover. If you're using them with wall mounts that cross over at 80 or 100 Hz, I assume you'd set the speakers to "small" in the receiver and send the bass to the DWM's. They aren't really subs, so I don't think you'd want to cross them over to the big panels, just use them in parallel. The exception might be the smaller speakers like the MMG and MG 12 that don't necessarily go down to 40 Hz, not sure what they recommend in that case. MMG's will play louder if you cross them over to a sub a bit high, at say 80 Hz, but I'm not sure what the SPL capability of the DWM's is, they use the wall reflection to increase effective baffle size but they're still small speakers.

[andyr]

I want to think the Josh is correct, that the .7's have series x/o necessitated by the use of quasi-ribbons in the bass/mid's. 

Jim

Jim, why do you think that using ribbon-wire on the mylar for the bass panel in the 1.7 (vs. round-wire for the bass panel in the 1.6) necessitated a change from the classic Magnepan parallel XO to a series XO? 

Regards,

Andy

[andyr]

I'm not sure I understand. In my biamped IIIA's, I use one stereo amp for the bass drivers and one for the mid/highs so the only difference between this arrangement and the stock arrangement is the bass panel is on its own amp. I still have the outboard passive crossover that splits the mids and highs and the bass is separated out at the active crossover upstream. I'm using a Dahlquist LP-10 which has active control on the bass output but the mids/highs are separated with a single cap.

In this scenario, the ribbons are protected by the passive crossover in the same way as in the stock setup (I've rebuilt the passives outboard of course). I also keep a fuse on the ribbons just for extra protection.

The only way I could see the ribbons being possibly damaged would be in a tri-amp setup where there is a dedicated amp to the ribbons. I've found that the bulk of the load is in the bass panels so this setup allows a beefier amp on the bass panels and a less powerful one on the mids/highs. I've been really happy with this setup for several years now. The dynamics and control over the panels is hard to beat compared to a stock arrangement.
Steve

I can't be sure from your description of what you've done, Steve, but your use of the term "bi-amping" seems to be very different to mine? 

Forget the sub - are you driving your IIIas with 1 stereo amp or 2?

If you're driving them with 1 amp, you are not biamping your IIIas ... the second amp (and its active XO) are associated with the sub.  If you are driving them with 2 amps (1 for the bass panels and 1 for the mids/ribbons) ... do you emply the external passive XO box (or a replacement) or a 2-way active XO?  If the former, you are "passively bi-amping" and I suggest you are not getting as much SQ out of that scenario as you would if you junked the passive bass/mid XO and went for active here.

Regards,

Andy

[medium jim]

Andy:

We know that Magnepan went to the quasi ribbon as it doesn't delaminate as did the round aluminum wire did.  In the same vein, to control warranty repair costs. 

As to why they may have opted for series vs parallel, I would assume there were different electrical characteristics associated with the quasi ribbon setup and that series might make them slightly more efficient with respect to spl.

Maybe these are a couple more things that Josh can inquire when he's speaking to Wendell.

Jim

[andyr]

Andy:

We know that Magnepan went to the quasi ribbon as it doesn't delaminate as did the round aluminum wire did.  In the same vein, to control warranty repair costs. 

Jim

Probably.  However, the fact that more area of the mylar is covered by the flat-wire (than with round-wire) suggest to me that it controls the mylar better ... so there's a sonic improvement at play here - not just an expected reduction in warranty-repair costs. 

As to why they may have opted for series vs parallel, I would assume there were different electrical characteristics associated with the quasi ribbon setup and that series might make them slightly more efficient with respect to spl.

Davey will have more competence to answer that, than I, but I can't see how using flat-wire rather than round-ware will influence a choice for a series XO vs. a parallel XO.

However, the idea expressed earlier that by stopping people from biamping, Magnepan is again reducing the likelihood of warranty repair ... makes sound business sense, IMO.  And Magnepan is a very pragmatic company. 

Regards,

Andy

[medium jim]

Andy:

So basically we are in agreement on both accounts, so why the interrogation?  Don't you think that the goal was to increase QC or in other words, a reduction in warranty or otherwise repairs?

One of the major issues with round aluminum wire and Mylar was delamination. The fact that the cure, full quasi ribbon panels resulted in what some say, sounds better, was a good outcome.

I agree that Davey would have a good working knowledge of why series vs parallel was opted for, if indeed it was.

Jim

[Davey]

My theory on the series/parallel change...if it really is a change...is that system impedance swings created by the non-textbook electrical alignments of the crossovers are more benign with the series networks.
With a "textbook" electrical crossover (that sums electrically flat) it wouldn't make any difference whether the network was parallel or series.  (It would be a flat line impedance.)
However, all of the Maggie speaker networks I've seen are considerably skewed from an electrically flat response.  If you simulate you'll see the series network creates a nicer looking impedance curve for (equivalent) non-textbook networks.
This wouldn't be an issue with power amplifiers that are functioning as voltage sources (very low output resistance), but it seems many audiophiles nowadays don't use power amplifiers that achieve that standard.  (Many vacuum tube amps.)  Thus you could have wildly different tonal balances depending upon the amplifier used.  This "variation" can be reduced somewhat by switching to a series network.

Some other theories regarding reduced warranty costs, reduced production costs (no external crossover for the 3.7), etc, etc, probably have validity too.  Me thinks that Josh will strike out getting information from Wendell on these questions, but no big deal.

Just my two cents worth of speculation.

Cheers,

Dave.

 

[Robin Hood]

AFAIK, they run them full range when they use them to augment the woofer panel area of the floor standing speakers. The Mini Maggies are fed off their internal crossover. If you're using them with wall mounts that cross over at 80 or 100 Hz, I assume you'd set the speakers to "small" in the receiver and send the bass to the DWM's. They aren't really subs, so I don't think you'd want to cross them over to the big panels, just use them in parallel. The exception might be the smaller speakers like the MMG and MG 12 that don't necessarily go down to 40 Hz, not sure what they recommend in that case. MMG's will play louder if you cross them over to a sub a bit high, at say 80 Hz, but I'm not sure what the SPL capability of the DWM's is, they use the wall reflection to increase effective baffle size but they're still small speakers.

I agree that when using the DWM woofers with the floor standing Maggies the idea is to run both the floor standing Maggie and DWM woofers full range in parallel.

The problem is that the top end of the DWM woofer, which is flat to 1500 Hz, is limited by its internal crossover which is fixed to approximately 300 Hz. The bottom end of the floor standing Maggie is limited by the low frequency response of the specific Maggie and varies among the different models.

Thus when you use multiple DWM woofers to achieve the Tympani gold standard of bass with the floor standing Maggies, the top end of the DWM woofers is always approximately 300 Hz unless you disable the internal crossover in the DWM and either run them up to 1500 Hz or use an external crossover to limit the DWM to whatever you want, say from 80 Hz to 500 Hz.

So if you want to use multiple DWM woofers in parallel with the 20.7 you may want to set the external crossover to the DWM to 60 Hz to augment the woofer panel area of the floor standing speakers. Perhaps for the 3.7 you may want to set the external crossover to 80 Hz. Perhaps for the 1.7 you may want to set the external crossover to 100 Hz. 

For the smallest Maggies, the Mini Maggies, you may want to set an external crossover to 300 Hz, though in this case you would never want to run the Mini Maggies lower than 300 hz, since I believe that is the optimum frequency limit of the Mini Maggie midrange/tweeter panels that Magnepan has determined. Of course in the case of the Mini Maggies the cost effective solution is to just use the internal crossover in the DWM woofer and run the midrange/tweeter panels in series.

If you were using the DWM woofers in parallel or series with one of the Martin Logan hybrid electrostatics, you would want to disable the internal DWM crossover and use an external crossover set to about 500 Hz for the top end of the DWM. For the Martin Logan hybrid, you would want to disable the cone woofer and use the external crossover set to about 500 Hz for the low end of the electrostatic panels.

I may be mistaken but I am beginning to believe that the DWM woofers have not been around long enough for people to explore the possible uses and mods, especially since it involves voiding the warranty DWM woofers. Of course I also believe that many Maggie modders have found that crossover mods to stock Maggies have been very worthwhile.

[andyr]

This wouldn't be an issue with power amplifiers that are functioning as voltage sources (very low output resistance), but it seems many audiophiles nowadays don't use power amplifiers that achieve that standard.  (Many vacuum tube amps.)  Thus you could have wildly different tonal balances depending upon the amplifier used.

Cheers,

Dave.

Wow, Davey, hope you've got your flame-proof undies on, coz the tube jihadists are going to be coming your way!! 


Regards,

Andy

[medium jim]

Wow, Davey, hope you've got your flame-proof undies on, coz the tube jihadists are going to be coming your way!! 


Regards,

Andy

Nice, blame it on us "Bottleheads" who love tubes.   

Jim

[josh358]

Andy:

We know that Magnepan went to the quasi ribbon as it doesn't delaminate as did the round aluminum wire did.  In the same vein, to control warranty repair costs. 

As to why they may have opted for series vs parallel, I would assume there were different electrical characteristics associated with the quasi ribbon setup and that series might make them slightly more efficient with respect to spl.

Maybe these are a couple more things that Josh can inquire when he's speaking to Wendell.

Jim

Sure, added it to the list. (Which is growing amazingly long!)

I don't think delam or warranty costs is why they went to the foil, by the way. It's a signal quality issue -- foil sounds better since, as someone just pointed out, it controls more of the diaphragm. It also seems to damp it better, at least, judging by my informal "tap the MMG" tests and the observation that the .7's don't have the "Mylar noise" in the background that the wires do. It may also be worth noting that the first Maggie ever made used foil, and that Jim Winey intended to use foil in production but couldn't for reasons that I haven't seen specified. And every time they've replaced wire with foil the reviews have said the foil sounded better. It does have some disadvantages, e.g., you can't double the foil to get more current (well, you can, but I think it requires a different fabrication technique -- the planar drivers that do that, like the little BG's, use etching or sputtering rather than foil and glue).

The delam issue should have been solved by the new adhesives they introduced in 2005. Also, according to Wendell, it costs more to apply the foil than it does to apply the wire.

[josh358]

I agree that when using the DWM woofers with the floor standing Maggies the idea is to run both the floor standing Maggie and DWM woofers full range in parallel.

The problem is that the top end of the DWM woofer, which is flat to 1500 Hz, is limited by its internal crossover which is fixed to approximately 300 Hz. The bottom end of the floor standing Maggie is limited by the low frequency response of the specific Maggie and varies among the different models.

Thus when you use multiple DWM woofers to achieve the Tympani gold standard of bass with the floor standing Maggies, the top end of the DWM woofers is always approximately 300 Hz unless you disable the internal crossover in the DWM and either run them up to 1500 Hz or use an external crossover to limit the DWM to whatever you want, say from 80 Hz to 500 Hz.

So if you want to use multiple DWM woofers in parallel with the 20.7 you may want to set the external crossover to the DWM to 60 Hz to augment the woofer panel area of the floor standing speakers. Perhaps for the 3.7 you may want to set the external crossover to 80 Hz. Perhaps for the 1.7 you may want to set the external crossover to 100 Hz. 

For the smallest Maggies, the Mini Maggies, you may want to set an external crossover to 300 Hz, though in this case you would never want to run the Mini Maggies lower than 300 hz, since I believe that is the optimum frequency limit of the Mini Maggie midrange/tweeter panels that Magnepan has determined. Of course in the case of the Mini Maggies the cost effective solution is to just use the internal crossover in the DWM woofer and run the midrange/tweeter panels in series.

If you were using the DWM woofers in parallel or series with one of the Martin Logan hybrid electrostatics, you would want to disable the internal DWM crossover and use an external crossover set to about 500 Hz for the top end of the DWM. For the Martin Logan hybrid, you would want to disable the cone woofer and use the external crossover set to about 500 Hz for the low end of the electrostatic panels.

I may be mistaken but I am beginning to believe that the DWM woofers have not been around long enough for people to explore the possible uses and mods, especially since it involves voiding the warranty DWM woofers. Of course I also believe that many Maggie modders have found that crossover mods to stock Maggies have been very worthwhile.

I think you're right, there hasn't been much experience with them yet. Hadn't thought about using them with the Logans, I can see wanting to disable the internal crossover if you did, as well as using an external crossover as you suggest for situations in which you'd want to cross over lower down. One concern I'd have about disabling the internal crossover is power response -- I don't know what the width of the panels is but whatever their frequency response, they're going to start to beam as wavelength approaches the width of the driver. Also, you need to have frequency response above the crossover point because the driver is still making a sonic contribution several octaves up, depending on the slope of the crossover, and you can hear the contribution until it's something like 24 dB down. But if the Logans don't go below 500 Hz, you'd definitely want to do whatever you could to fill in the gap, so bypassing the internal XO would certainly make sense.

With the 20.7's etc. you might want to have some fill in the 100-250 Hz region, not just below 100 Hz, because you can get suckouts there depending on room modes and speaker/listener positions. It's going to vary from room to room, as Wendell points out they can only tune bass response for an average room and position.

[medium jim]

Sure, added it to the list. (Which is growing amazingly long!)

I don't think delam or warranty costs is why they went to the foil, by the way. It's a signal quality issue -- foil sounds better since, as someone just pointed out, it controls more of the diaphragm. It also seems to damp it better, at least, judging by my informal "tap the MMG" tests and the observation that the .7's don't have the "Mylar noise" in the background that the wires do. It may also be worth noting that the first Maggie ever made used foil, and that Jim Winey intended to use foil in production but couldn't for reasons that I haven't seen specified. And every time they've replaced wire with foil the reviews have said the foil sounded better. It does have some disadvantages, e.g., you can't double the foil to get more current (well, you can, but I think it requires a different fabrication technique -- the planar drivers that do that, like the little BG's, use etching or sputtering rather than foil and glue.

The delam issue should have been solved by the new adhesives they introduced in 2005. Also, according to Wendell, it costs more to apply the foil than it does to apply the wire.

Funny thing Josh, you and I both like our older Maggies', go figure . 

Understand, I'm not faulting Magnepan and as Andy properly noted "Magnepan is a very pragmatic company." emphasis added  If Magnepan was able to:

1 Make their .7 series perform better because of flat ribbon as opposed to round wire;

2 Decrease overall production costs;
a Increased initial production costs + less warranty costs= decreased costs;

3 Keep the MSRP close to what the 3.6 and 20.1 was a decade ago;

4 Have low consumer complaints, i.e., lack of ability to bi-amp.

You have a recipe for success!

Jim

[berni]

Maybe a stupid idea..
Josh you wrote:
With the 20.7's etc. you might want to have some fill in the 100-250 Hz region, not just below 100 Hz, because you can get suckouts there depending on room modes and speaker/listener positions. It's going to vary from room to room, as Wendell points out they can only tune bass response for an average room and position.

I know that planars have some problems in the range you already wrote about (100-250 hz) because of the drum resonances and other things, so you have to tune the foil to get it sorted in a way. But depending on room size and shape the tuning had to be individual. How about a way to tune it to our needs?

[josh358]

Maybe a stupid idea..
Josh you wrote:
With the 20.7's etc. you might want to have some fill in the 100-250 Hz region, not just below 100 Hz, because you can get suckouts there depending on room modes and speaker/listener positions. It's going to vary from room to room, as Wendell points out they can only tune bass response for an average room and position.

I know that planars have some problems in the range you already wrote about (100-250 hz) because of the drum resonances and other things, so you have to tune the foil to get it sorted in a way. But depending on room size and shape the tuning had to be individual. How about a way to tune it to our needs?

Not silly at all, I was thinking similar thoughts earlier this evening.

Apogee did have adjustable tension on their woofers but that's expensive and I think it would have limited utility, you have to be able to tune individual resonances.

So that leaves electronic correction, which isn't really great for suckouts since it reduces maximum SPL.

I did think that if they built in a rolloff switch, it would help people who want to use them in small rooms. But that would add to the cost of the speaker and most people don't need it, so I doubt they'd want to do it.

So unless someone can think of something fiendishly clever, I think we'll have to stick with what we have now -- some combination of placement, room treatment, extra woofers, and EQ.

That last would be a lot easier if someone made a little digital EQ box that doesn't digitize the highs. I'm not sure if this is practical though because of latency through the digital section. You couldn't use a linear phase FIR filter, you'd be limited to minimum phase IIR filters. It would also require bi-amping. So it rapidly becomes a costly fix in an analog system. In a digitally-sourced system, it's trivial.

[medium jim]

Some have opined that the flat quasi ribbon now used on the 3.7 and 20.7 controls the mylar better, isn't this sort of what the Razor Mod does, i.e., dyna mat on the mylar in strategic points to dampen? 

Jim