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Past and Present Reflections

Posted 17th February 2010 at 12:17 PM by smoketest

[originally written in May 2009]

Hello, my name is Brian and I’m a user. A Magnepan user. I, like perhaps many of you, have a mixed relationship with my Maggies. This is, in a way, a sad story of more than 20 years of listening dissatisfaction. At least until recently, but before we discuss that please indulge me the time to bore you with some history.

Consider your roaring twenties, or at least consider mine. In the early 1980s I was fortunate enough to bag a full set of precut particle board for a pair of Speakerlab K-Horn woofers. I added a 15 inch woofer, a full width Altec horn mid-range, a Heil tweeter, a home brew cross-over network and our little 2 bedroom house in West Palm Beach truly did roar. In fact our poor neighbor across the street had to walk over and ask us to turn it down a couple of times. With a borrowed Audio Research D-75A and a home made tube only pre-amp, it sounded like a rock concert.

After moving those behemoth speakers a couple of times (sans roadies), I decided to sell them before I moved, yet again, to California. They went for a very reasonable $500 for the pair and I hope my good friend Rudy still enjoys them, I have to call him one day and find out.

Once settled in California, I intended to find some great and hopefully more portable speakers. However, I instead auditioned tall Acoustat electrostatics which required a “head in a vise” listening position, and the Magneplanar MG IIIa. The Maggies sounded fantastic in the store, clear and clean, open and transparent. The store proprietor, John Garland of Garland Audio, came to my apartment and helped me set them up. He noticed my Fulton Gold speaker cables and talked about once using a pair as ropes to pull down a wall when he set up his store. (Bob Fulton was one of the first heretics to claim that wire made a difference in sound. If you’ve never seen them, they make Monster Cable look like iPod headphone cord. Approximately 24 feet each of stranded silver plated oxygen free copper bigger than most auto jumper cable wire.)

When John saw my 1960s vintage Dyna Mark III 45 watt/channel amps and home made pre-amp with a big ugly power supply chassis mounted in a salvaged open top instrument chassis, he was likely horrified although he never let on. His horror was justified, because those electronics that were great with the 100+ dB efficient K-horn speakers did not have the power to drive the inefficient Maggies. I got everything set up and that system could barely drive the Maggies to a listenable level. This was a great lesson in the interdependence of components.

To get more power, I ordered a DC-100 100 watt/channel MOSFET output power amp kit from Erno Borbely. After assembling this on my apartment floor over a weekend, I hooked it up and, as I recall, it sounded great. However after 2 or 3 days it inexplicably made a popping noise and stopped working. After 20 years I still have the pieces and hope some day to debug it. I struggled on with the Dynas and Maggies for a couple of years until after the next move, this time to Illinois.

When I heard that Hafler was going out of business, I went to my local audio store in Libertyville and asked if they had anything on close-out. Turns out they had a DH-500 kit and I got it for $700 including sales tax. I thought it was a great deal at the time but now I think it was probably retail price. As I recall the PC boards were already stuffed so it was mostly a matter of mechanical assembly to get this 250 watt/channel “arc-welder” up and running.

This amplifier could definitely drive the Maggies and they sounded pretty good for a while, until the output tube in my home-made preamp died. This was a 6973 dual triode used as a low impedance follower and I could not find a replacement. Back to the local audio store, for a bargain. I wanted something inexpensive to use “temporarily” while I saved my money for a really good pre-amp. (If you’re thinking “yeah, right, you’re just a cheapskate” — bingo.) I went home with a used Harmon-Kardon Citation Eleven.

This was a decent combination of components, although the sound was not exciting nor even close to “live.” The Citation had one great feature that I was not accustomed to with my home-made pre-amp: six(!) inputs. It also has the cleanest silicone lubricated volume controls and switches you can find, and the chassis is modular so boards can be unplugged and replaced easily. After a year, it changed again from not live to truly dead – the output stage of the Citation died. I yanked out all the boards, built a regulated power supply, a phono stage and an output buffer from op-amps and stuffed them in with a minimum of modifications to the chassis wiring. Again the system was listenable but not outstanding. For about 14 years I used this system with almost no soldering required, except the time the speaker relay in the DH-500 went bad.

By now you’re wondering, “OK, SO WHAT’S THE POINT?” All right, fast forward to 2007. By now we’ve moved to Greer, South Carolina, my kids are older and there’s a little more time available for hobbies. I get interested in more serious listening again and also start messing around with circuits and maybe building some speakers. (I convinced a friend of mine with an old pair of salvage AMT speakers in his barn that he should donate them to me so I could use the Heils.) I determined that after 20 years the voice wires in the Maggies had open circuited and the diaphragms were coming apart. About the only thing still working were the ribbon tweeters.

I called up Magnepan and they said they could repair them to like new condition, so I boxed them up and sent them to White Bear Lake, MN. When they arrived the ribbons were ruptured too, so the shipping gorillas did their job. After about a month they came back as good as new and, miraculously, the ribbons were intact. Now that they were operating in good condition I spent a couple of weekends rearranging them to find the best listening position. All to no avail — there was no place they can sit in my listening room and sound great, at least no place I tried. They were positioned in the typical location about 4 feet apart, 3 feet from a front wall, centered between 2 side walls (see figure 1). The room is 15 x 18 feet with a large opening in the wall behind the sofa. They were angled to point to the sweet spot listening seat on the sofa. I moved them forward, back, changed the angle, moved them apart and closer together, nothing helped.

[IMG]http://listen.belleson.com/wp-content/uploads/2009/06/reflect1.png[/IMG]

Figure 1 – Conventional speaker placement, rear reflections can interfere.

The Maggies, as you probably know, are planar bipolar radiators, so the rear driven sound bounces off the wall behind them and can interfere with the front waves, depending on the distance. Finding a good position for them has always been one of the big challenges, again in total opposition to the K-horns that can only go in adjacent corners. So I began the search for new speakers. There are no “local audio stores” here in Greer so I was stuck perusing Stereophile, The Absolute Sound, and Best Buy (just kidding). Again the idea was to find some small, portable speakers that go from 20Hz to 20KHz in any listening room, with perfectly flat response, no resonances, and really cheap. I didn’t have much luck, I’m now paying for piano lessons and could not audition anything, so nothing new appeared in the listening room. I even listed my Maggies on craigslist.com thinking I could find something smaller and uni-directional for their selling price. Fortunately no one bit…

In summer 2008 at a friend’s house, a High School Musical CD was playing in another room. I could hear the treble beaming at my ears from a third room. This was disconcerting and I got up and moved around to see how the sound reflected from the source room to the second room then to the third room where I was sitting. Odd, even though the K-horns used internal reflections to create a bass wave front, I never realized how directionally reflective sound waves can be…

Earlier this year (2009), I finished a modified version of the Jung Super Regulator* design (that’s another story altogether) and built it. I bolted it into the Citation Eleven. Suddenly there was BASS in the music that was never there before; there was clarity and silence. There still was no stage presence and no “live” but this was such a significant improvement that I reconsidered the Maggies.

In February I took a drive to Charlotte to see Joe Grado at a headphone symposium in Charlotte. He’s a true legend, I really like the Grado SR-60 headphones and I wanted to hear anything he had to say. He told some very interesting stories, one in particular involved Frank Sinatra and I hope every syllable is true. But his primary discussion was related to his new Holographic microphone design, which is amazing. This new microphone makes no attempt to pick up the direct sound from a performer, instead it picks up reflections. I listened to it on monitor headphones and could hear and localize conversations from all over the hotel room. It was amazing.

During the discussion he mentioned that two people four feet apart can’t hold a conversation in an anechoic chamber because they can’t hear each other, illustrating that most of the sound we hear is reflected. He also mentioned that he had set up speakers in his listening room to take advantage of this fact. I tried to get more information by asking directly (I mentioned the Bose 901 Direct/Reflecting idea and he scoffed) and he said he set them up to radiate horizontally. This is closer to how Maggies work than how boxed cone drivers (point source) work, but I didn’t feel like I understood.

Over the next couple of weeks I thought about what he said, and one night while listening I had an idea. I immediately jumped up and pushed the Maggies into the corners of the room, with the planes of the diaphragms at a 45 degree angle to both walls (see figure 2). I sat down in the listening chair and there was space, imaging and source localization. I walked around the room and everywhere they sounded MUCH better than before. With this placement, the problem of front/rear interference is minimized and the wave fronts have the entire diagonal distance of the room to fill, and parallel wall interference is also minimized.

[IMG]http://listen.belleson.com/wp-content/uploads/2009/06/reflect2.png[/IMG]

Figure 2 – Speakers in the corners reflecting across the diagonal.

Finally the Maggies sound great. Well, almost. The sound stage was more like an outside concert than an auditorium. In several listening sessions I adjusted the speakers gradually closer to each other, still against the wall and with their edge pointed toward the listening seat, until the stage width seemed correct (see figure 3). Wow. It’s like hearing those MG IIIa s for the first time, after all these years.

Listening to a live swing band recording, I can localize the horns. With a Paul Desmond live recording I can almost smell the bar smoke. When I put it to 11 with a rock album it's as brash as a live concert. And one of my audiophile friends mentioned that there is more bass than he expected from the Maggies.

[IMG]http://listen.belleson.com/wp-content/uploads/2009/06/reflect3.png[/IMG]

Figure 3 – Speakers’ edge points toward the listening point, reflections go wherever.

The only small caveat is, due to the height of the speakers my listening seat sounds below the level of the stage. Note that your results may differ with different speaker types, unipolar radiators or the smaller Maggies that sit in a non-vertical angle. But with nothing to lose and for zero money, a little experimentation may yield a miraculous improvement in your listening.

June 2009 addendum: For some time the left channel sounded weaker than the right and I could never isolate the problem. On a whim I took out the 5 amp fuses from the Hafler DH500 – the fuse wire in the left channel fuse was brown in the middle. I put it on the Ohm meter and it showed 1/2 Ohm. HOLY COW. Not blown, but damaged. That half Ohm caused a 6% power loss in the left channel. New fuses in both channels and we’re back to political parity between the left and right. I wish I could afford some HiFi Tuning SilverStar fuses.

* Walt Jung, “Regulators for High Performance Audio, Parts 1 & 2,” The Audio Amateur, Issues 1 and 2, 1995.
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