How would you design the Ultimate Magnepan?

[AJ Soundfield]

are panels something that you have considered experimenting with?

No.
I've heard plenty in my time.

I was thinking of that Gilbert Briggs quote when he first heard Quad's ESLs.

The Quads are quite different, with the concentric arrangement, closer to a point, than line source, like the typical planar-mags and ESLs (Magnepan, ML, etc).
I prefer point source/horn dynamics, no panels for me. I get my diffuse energy by other methods. Of course my horns are planar-mags, so there is some preference there too.

cheers,

AJ

 

[Purité Audio]

I have heard quite a few different panel designs, I remain indifferent , planar magnetic drivers, I am not familiar ,
we used to retail LANSCHE loudspeakers they used a plasma tweeter which was fun, but you wouldn't want to stick anything in it.
Keith.

 

[amirm]

I have heard quite a few different panel designs, I remain indifferent , planar magnetic drivers, I am not familiar ,

Well, I am quite familiar with planar magnetics. We had a high-end one for about a year or more:

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For the benefit of AJ who probably can't tell a speaker from hole in the wall, the top row are JBL Synthesis speakers. That was intended to be our " back up" system if the planar magnetic speakers below them didn't perform. But we were "sure" they would. The planar magnetic system has two parts. The speaker array of small drivers for the low end and the ribbon drivers on their side. Both systems were crossed over at 80 Hz or so and hence were not responsible for playing deep bass.

Note that these are NOT dipoles. The Planar Magnetics have an enclosure behind them and you are just seeing the face of them in the above picture.

The initial impression of the planar system was very positive. Grand wall of sound that would come at you. In the midst of getting everything running, Bruce Brown came over for a visit and I demoed that system to him. To AJ's dismay, he asked me a critical question, "do your customers like that large sound?" And then it hit me like brick. Everything I was playing for him regardless of album, had that grand and tall impression. For some music that was the right thing. But I quickly grew tired of the effect and the sameness it gave to everything I played.

The problems did not stop there. I would often find vocals to sound wrong. The system came with Audyssey Pro so we messed endlessly with that. That was when I developed my dislike for Audyssey just the same . You would run the calibration twice in a row and get two different results down to it detecting "out of phase" errors. And of course it would lie about what it had accomplished because it would never make a measurement post correct.

Meanwhile the little, ugly JBL Synthesis system performed from day one at half the price (the planar magnetic system retailed close to $150,000 with its included amplification and processor). The acoustically transparent system as you see below allowed for perfect blind A/B comparisons, stopping the eye from preferring the much prettier planar magnetic system:

I then did some measurements to get to the bottom of it. I don't have the picture handy but the response from the planar system was not pretty. The crossover was very poorly handled and the response was just ugly. Long story short, we ripped out the system until recently when we upgraded to JBL M2, the JBL system powered the theater allowing us to sell tons of systems with its performance.

The second round of my experience in this manner which I have documented a number of times was taking the Harman test twice and giving very poor scores to the ML speaker in blind evaluation. Here is a cell phone shot in the dark (and hence the blurriness) of my scorecard for the first track that played:

Speaker "A" that I gave the rating of "4" to out of 10 is the ML.

All of this is "recent" experiences in the last 4-5 years. Prior to that, I always liked the these speakers but now, for good or bad, no longer prefer them. And can "hear" the same issues I have with them at shows.

Let me emphasize again that the effect that these speakers add to the sound can be captivating when it works. That large wall of sound can be amazing on such things as organs, orchestral music. And even other types. If you don't get tired of it as I did, then more power to you.

 

[amirm]

How Ethan sat beside him and Amir worked with him....and still didn't pick up anything is beyond me....

Get your facts right buddy! I hired JJ and made him the audio architect in my team to spearhead the re-write of the terrible audio pipeline in Windows XP which he did. Having spent plenty of time with him, the one thing I know for certain is that 99% of people can't follow what he says as he uses short-hand speech and assumes you are equal to him in knowledge of mathematics and signal processing. That means I am confident there is not a thing you have learned from him. Live with that buster!

 

[Thomas savage]

Kind of sounds like what my old krell amp did, everything sounds big so ruins the beauty of many more subtle recordings. Big rock band... Sounds massive, just a girl and a guitar still massive. Gets boring quick.

 

[Purité Audio]

Is that Neil Young, or you when you had hair?
Keith

 

[amirm]

It is not me. It is someone who worked in the company and I asked him to stand there to give it scale. I am MUCH nicer looking.

 

[Purité Audio]

Remember we have all seen you grabbing the mic at that AP lecture!
Keith

 

[amirm]

Ok lets see if we can wrap this up quickly before Fitz says something even dumber.
Back to what JJ said, in the "Time alignment" thread, he's referring to (inter) driver phase integration at the source, not inter channel. He was a bit ambiguous with the "surprisingly low", but to my knowledge, 700hz on up and you're good to go, especially with as you noted percussive attacks. I'll have to dig through my library for the AES references, but suffice to say, your XO being 180hzz and the panel running full bandwidth above that is going to automatically take care any multi-driver phase integration issues >700Hz.
Note I'm not saying inter-ch isn't important but relates more to spatial effects than the percussive ones you referred to, which is a source issue. Btw, some great quotes from JJ there and his linked ppt is even better. If you can understand what he's saying (sorry Fitz), you'll see it aligns quite well with Dr Toole, Greisinger, etc.
It's like a blueprint on how to make speakers, being gifted for free.
How Ethan sat beside him and Amir worked with him....and still didn't pick up anything is beyond me....
As to Brians comments, well as you say those were old measurements...and still make no sense to me.
Ok, so to complete the thread jack, I'm guessing you took issue with Amirs poo-poohing of panels, but as I stated, those results are based on specific models with issues beyond the large radiating diaphragm and dipole>monopole bass integration.
Lastly what we measure with a single pressure mic sample at some point in the soundfield, is quite different from what we hear perceptually with binaural hearing. There is some relevant data there, sure, but limited. Things are a bit more complex that that, I'm still not sure what your "mono" measurement is showing, but for a panel with 180hz XO, a 1/6th octave resolution FR from each channel independently > 500hz or so is mostly what one would need, imho.

cheers,

AJ

Maybe someone else is able to see the answer to Ray's question but I don't. Here it is again. This is his measurements:

He is asking why, the phase graph line at the bottom, flatlines and no longer changes like it does for everyone else's measurement.

 

[amirm]

Remember we have all seen you grabbing the mic at that AP lecture!
Keith

That's right. I looked handsome there despite the fact that they did not get my good side! They shot me without my knowledge and permission so it is not the best portrait of me.

 

[Thomas savage]

That's right. I looked handsome there despite the fact that they did not get my good side! They shot me without my knowledge and permission so it is not the best portrait of me.

Hey amir are those guys from that presentation still not returning your calls and cancelling the workshops you sign up to at the last minute when they see your name on the list

 

[amirm]

They are. So I have registered as AJ for Axpona. His questions are always dumb so they don't mind that one bit.

 

[DonH56]

I sort of quit following this thread and was sick as a dog yesterday so am way behind. Flat phase is often a consequence of the crossover design. It is not necessarily a good thing but not bad either. Linear change in phase with frequency leads to constant group delay. That means every frequency is delayed equally and such a design provides excellent pulse (transient) response. A number of speaker designers have taken that as a goal but there are so many variables that I am not sure it has won or lost market share; just one more design variable in the sea.

Planar magnetics use a long coil of wire or a ribbon structure, either of which tends to be mostly resistive. A number of them use low-order crossovers and present an almost purely resistive load. I personally prefer higher-order crossovers, but unless you do it actively, that leads to larger impedance variations (planar dynamic or not).

ESL's have a big ol' transformer through which the signal flows to drive the panels. Technically, the diaphragm in an ESL is usually at a fixed DC (voltage) potential, and the stators (usually metal plates with holes on front and back of the speaker) are driven by the signal from the transformer to provide a "push-pull" drive. The panel itself is a capacitive load, but the impedance is more complex due to the transformer coupling. It's been a while, but I think most ESLs exhibit a falling impedance with frequency but few "bumps".

Both planar types have some impedance ripples due to things like panel modes and crossover design (especially hybrids like ML, Sanders, etc.)

Conventional speakers use a voice coil that looks mostly inductive, and often a more complex crossover, plus may have features like ports, so the overall effect is that they tend to have more more impedance variation over frequency. Like, 5 or 10 to 1 on the high side, and may dip to 1/2 or 1/4 nominal impedance on the low side.

All IMO based on foggy memory - Don

 

[RayDunzl]

Phase is such an obtuse topic that it definitely merits discussion, if not here, then in another thread.

That's a topic I have some interest in. I double-dawg-dares you to start one. Take your time. Maybe put it in the Library section.

Maybe someone else is able to see the answer to Ray's question but I don't. Here it is again. This is his measurements:

He is asking why, the phase graph line at the bottom, flatlines and no longer changes like it does for everyone else's measurement.

My real question is to see measurements for other planars or other speaker types at all.

I figure mine 'flatlines' because it doesn't muck up the phase much. What do others do?

 

[AJ Soundfield]

He is asking why, the phase graph line at the bottom, flatlines and no longer changes like it does for everyone else's measurement.

No idea since he also says it was a "stereo" measurement!
A single channel one of his MLs and maybe the 363 for reference would have been helpful.
Anyway, going to listen to some MLs tomorrow, may drag my portable measuring setup for S&Gs.

 

[AJ Soundfield]

I figure mine 'flatlines' because it doesn't muck up the phase much. What do others do?

While waiting for Fitz to tell us the answer, I thought about it some more - can't help but wonder if it isn't the overwhelming amount of FRs you would have summed at the mic in the far field with both speakers driven!
IOW exactly what "phase" have you measured there with such a method?
Have you ever asked JohnM on the REW forum on HTS?
Anyhow, in terms of binaural perception, I don't think that tells you much if anything. The summed FR at least gives you something regarding spectral balance at the mic, though I most definitely wouldn't use it for EQ >500hz or so.

cheers

AJ

 

[RayDunzl]

He is asking why, the phase graph line at the bottom, flatlines and no longer changes like it does for everyone else's measurement.

I haven't seen everyone else's measurement.

While waiting for Fitz to tell us the answer, I thought about it some more - can't help but wonder if it isn't the overwhelming amount of FRs you would have summed at the mic in the far field with both speakers driven!

Here's the left speaker only, at the listening position.

As for "overwhelming", well... Here's both speakers with the phase of the right speaker inverted.

 

[DonH56]

Don, if you had to put in order of effectiveness the various Magnepan tweaks. What would top your list, vertical biamping, active crossovers, DSP, Razoring, etc...

Any thoughts on the 3.6s vs 3.7i's with their 1st order crossovers and quasi ribbon bass panel instead of the wire like mine. I would like to upgrade to the 20.x series speaker but my room is only 12'.5 wide by 26' long.

Hi sir, I missed this in the mass of posts, sorry. Disclaimer: It has been years since I did any mods on mine or anybody else's speakers. And these are my opinions, based on my current system (unmodified) and past experiences. I must also make very clear that I have moved over the years from an "I can hear the gnat on my cable elevator" golden-eared audiophile to a confirmed skeptic on most tweaks.

I would put room treatment first, especially damping the back wave, for the improvement in imaging it provides. Next would be properly integrating a good subwoofer; panels in general do not fare well with large LF signals. Distortion goes through the roof.

As for the panels themselves, bi-amping with an external crossover is what I have found yields the largest benefits. I prefer a higher-order crossover but there are always trades. I have never tri-amped my personal pair but have for others who swear by it. After years of doing it, my current system is driven normally and I find it works OK for me. Just got tired of the multiple amplifier and crossover hassles.

Since Magnepan crosses bass to mid/treble fairly low and with fairly low slopes, I have found little difference between vertical and horizontal bi-amping with similar amps, and Magnepan's require well-matched amplifiers. I bi-amped for years for "flavor" using a tube upper amp (ARC D-79) and SS hybrid (Counterpoint SA-220) for the bass. The bass amp was a compromise; much tighter bass than the tube amp, not as good as the big Krell and Levinson amps I tried around the same time, but provided the best integration with the D-79. These days I prefer a big SS amp for its tight bass and ability to handle the HF dip due to the ribbon tweeter, and can't afford a big tube amp.

Stand mods I have made, but rarely on mine, and have none currently. IME they measure a little better but do not sound different in a DBT (opinions vary).

While a number of folk claim significant improvements with crossover mods, again IME there was little change assuming stock frequencies and slopes were maintained. A number of mods make changes beyond just basic component swaps, changing the FR, and thus doing more than they expected. As for me, I have noticed improvements with after-market inductors that significantly lower series resistance, but little change with capacitors (I didn't really notice audible changes with capacitor swaps).

DSP is a great benefit in reducing the impact of the room but is not a complete panacea. Dipoles are tough due to that big back wave and a lot of DSP systems struggle with it IME (Audyssey, MCACC, YPAO, and now Dirac Live). And some of the schemes set a curve I do not favor, and/or don't allow me to tweak.

I don't know what "Razoring" is (may know it by a different name).

I don't have enough listening time on 3.6 or 3.7i models to say how they compare. The QR implementation is not all that different from your panels and my guess is, despite the hype, they aren't a huge difference. I do not think the 3.7i's use push-pull magnet structures like the 20.x's; that and panel size is the biggest difference. I did a lot of trials way back when and a little more recently (hard to find a dealer with 20's in stock, and when they do it is usually on display only for a day or so before going to someone who special-ordered them). I haven't heard anything to convince me to get 20's in a small'ish room (mine is about 13'3" W x 17'7" L by 8'6" H). So my advice, which is worth almost nothing in this case, would be to stick with 3.x and do some serious listening, preferably at home, to see if the 3.7i is a worthwhile upgrade from your 3.6's.

 

[TitaniumTroy]

Thanks Don, razoring is using Dynamat on the metal perforated sheet and the pole piece. You have to cut the strips pretty fine, as to not block the sound from passing thru. It is also used in a few other places but on the frame, but never touching the mylar, as I understand it anyway.

Amir, when I heard the Wisdom speakers at a dealer in FL. I too thought they sounded like a wall of sound coming at you, but nothing distinct you could point at imaging wise. I also heard a hybrid/monopole Wisdom speaker at one AXPONA show, with out the back dipole wave it sounded very forward, as did NewForm Research hybrid planers, also monopole. I prefer the laid back sound of a dipole compared to these speakers.

 

[DonH56]

Ah, yes, have seen that done, never did it myself AFAIK, not sure the benefit. Using various materials, soft and hard (saw one pair reinforced with welding rods, hmmm...) The theory is to dampen the magnet structure (magnets and frame) and add mass so it has less sympathetic vibration. I suspect the impact is small but cannot say from personal experience. Sounds like a lot of work!