Moving Iron Adventures


I have been a user of the London (Decca) Reference for the last eleven years. It has been good enough that I have had no desire to replace it—none at all! It seems a bit unusual for an audiophile to acquire some piece of kit and then say "That’s it!" for eleven years! Perhaps some of my complacency was due to having nice Quad tube amps and electrostatic speakers. But then things changed for me...

Everything got upset with moving house. My phono stage refused to work. My electrostatic speaker started to click and arc. And amongst it all, as I switched in other components to keep the music flowing, I listened more carefully to everything, including my turntable. I became aware my beloved Reference might no longer deserve that title as it was not now what it had been. Off it went to the UK, just in time as John Wright retires very shortly, for a full rebuild.

So in the meantime, I started to reluctantly expend monies on alternatives. I may have been a physician, but I had to stop working when I discovered that leukemia was to define my remaining life. Now I have to live upon my savings, and must balance audio delight against other necessities and a probable shortened lifespan. Go ask your financial advisor how to do that—I don’t have one and never have liked to think about money.

First job was to educate myself about other moving iron options, and several were available. None looked anything like a Decca cartridge: they have cantilevers! So, I learned that there were quislings who would make an MM cartridge where the magnets were not on the cantilever, but nearby both the fixed coils and the ferromagnetic mass on the end of the cantilever.They called the result moving iron. This was rubbish to a Decca user, but I realised it could only make any sense—compared to a moving magnet—if the moving ferromagnetic mass could be a whole lot smaller than the magnetic mass of an MM cartridge in the same place. Rare earth magnets have come along and make MM cartridges far better than they could be with iron magnets. Now what if the strong rare earth magnet sits still inside the cartridge body, and a small, lightweight sliver of ferromagnetic material sits on the end of the cantilever, waving around in the fixed magnetic field of the rare earth magnets, and induces a current in the fixed coils also in the cartridge body as it does so? Welcome to Grado, Soundsmith and Nagaoka. They do work, and surprisingly quite well. But don’t get excited, as they don’t work as well as the old Decca design.

Wisely or not, I bought an example from each company. A Grado Statement 3, a Soundsmith Sussurro MkII, and a Nagaoka MP-500. I didn’t tell you above that the London Reference was not my first Decca: I had bought a London Jubilee, and used it for about two weeks before I told myself that it was so good I simply had to spend twice as much to see what its big brother—the Reference—could do. I was still working then and could do that kind of thing. So now I could compare the new purchases to the Jubilee, knowing the Reference outclassed the Jubilee very handily.

All comparisons were on an SME Model 10 turntable, with a Series V tonearm. I was, and still am, surprised by the results. The MP-500 took about 15 hours to run in and after that it changed little. It was very close to the sound of the Deccas, so much so that I felt I had to take rather dramatic steps. I found another SME 10 table, used, and with the M10 arm (akin to the 309) that SME sold it with originally. I intended to sit the MP-500 on that that tonearm and table and that would delay the inevitable end of my two London Decca cartridges when they were no longer repairable after John Wright’s retirement. It is lively, dynamic and full of toe-tapping goodness.

I’ll sidetrack myself, and try to say what I’m trying to achieve. After 11 years of the London Reference, what is it that makes me want more of the same? I can’t speak to soundstage and imaging: I only have one somewhat damaged ear and I have no directional sense of hearing. Quality of sound is it—the whole thing—for me. Sure, I like some bass, and I don’t remember what my last audiogram said about high notes. But I did spend twenty five years flying to Toronto three times a year to attend two operas on each trip. I know what live orchestral music sounds like to my wretched ear, and I want more of it at home. I heard the difference when the COC moved from the O’Keefe/Hummingbird Centre to their new purpose built home. I was there for the first Ring Cycle and I mourn Richard Bradshaw’s early demise as much as anyone. In my earlier life, I had attended the Festival Hall in London for concerts (though with much cheaper seats!) As for modern live music, I have less experience. Two Supertramp concerts in Halifax, NS, and I was involved in supplying most of the pot for the Watchfield Concert in Wiltshire in 1975, where Hawkwind failed to turn up as booked. Attendees needed a lot of consolation.... So what am I looking for, aurally? Without clever terminology, it is the unconscious desire to tap my feet to the music. The sense that it is live, rather than a recording. I can’t identify anything in terms of frequency or timbre, and it probably comes down to responsiveness and timing to convince my ear that I’m hearing it live. Even SACDs through an Ayre C5-xe don’t quite match that, even if, analytically, I can’t say why they fail. Like Supreme Court Justice Potter Stewart on obscenity, "I know it when I [hear] it."

But to get back to important things, when the other cartridges came along...

The Grado Statement 3 proved to be accurate, honest and utterly boring. Very good at not reproducing surface noise. Maybe another tonearm would let it show its worth. I have gone back to it a couple of times, but I still get bored without being able to put a finger on a particular fault. Even after using an SPL meter to make sure I was comparing it fairly, it couldn’t compete against the (now returned and rebuilt) Reference.

The Sussurro MkII initially disappointed me. Eventually I RTFM and connected its 0.47mV output as an MC cartridge and set the loading to 800Ω as recommended. Now it is close to being as good as the Nagaoka, but doesn’t quite match it. But, along the way...

Like many, I have some older cartridges stored away. The Benz Micro Ruby 3 turned out to be a competitor, but the Ortofon Kontrapunkt C actually came the closest to the Decca sound I was trying to simulate. This surprised me a great deal, as I had used it some 12 years ago before the Deccas, where I thought it was an overly detailed and rather etched sounding pickup. I’m probably a bit more experienced at setting the VTA now, and my phono stage is certainly a lot more capable than the one I was using then.

So what to do now? I have spent good money and can’t honestly sell my purchases on as "you might like it but I didn’t" items. I have decided to keep my options open, with two tonearm pods custom machined to allow two extra tonearms to play on the two SME 10 tables. I was going to use my collection of SME 309 headshells, but the price of the cheapest SME tonearm still sold without a table underneath it is prohibitive. ($4.2kCDN each for the M2-9, which is more than I paid for a Series V arm!) So they will have to have Rega RB330 arms, and I can sort out the HTA and VTA by moving the pods around, and up and down). Pretty obviously pride of place on the Series V will be given to the London Reference, with the Jubilee as backup when it wears out, and if no one can be found to re-tip it at that time. The M10 arm will have the Ortofon Kontrapunkt C on it, and while I had thought I might replace when needed with a Cadenza Black, I’m now thinking I’d do better to re-tip it. The two extra tonearms will house the lovely MP-500 (I already bought two spare styli as it is that good!) and the Soundsmith Sussurro MkII. My phono stage (Musical Fidelity NuVista Vinyl) lets me attach up to five cartridges and remembers their settings as MM, MC, capacitance loading, resistance loading, ±6dB amplification, rumble filter on/off. The Grado Statement 3 goes in the cupboard with my old Benz Micro Wood H2 and Ruby 3. Should I get lucky and my recent bone marrow transplant lasts longer than expected, one day the MP-500 will replace the worn out Reference and Jubilee on the Series V arm. I don’t think that will happen in my time, but these ideas might provide guidance to others!

Right now, I allow myself one LP a day via the Reference. Everything else is played on the second table, so that provides the majority of my music now. In a couple of months the tonearm pods will be here, and I shall have three other options, populated as described, to prolong the lifespan of the Reference.

 

dogberry

Showing 9 responses by dogberry

It probably doesn't belong here, but my involvement in the weed thing was entirely accidental (yes, your Honour, it was an accident, I swear...) A funny story and one I'm happy to relate elsewhere. Believe it or not, I have never touched the stuff! It's legal here now, and I suppose I may end up with a good excuse if there has to be more chemo.

I was only 17 at the time and I can tell you I was much, much more interested in the fact there were naked women walking around the disused airfield where it took place that hot summer. We were told Hawkwind would be arriving by helicopter, but I don't even know if they were actually booked, or whether the idiots organising (to be generous) the whole affair were just using the name to attract visitors.

If I could buy another Reference it would solve a lot of problems. But there's none to be had, and it probably won't hurt me to have some variety in the way my vinyl plays.

Thank you for your kind thoughts! It's hard to remember now exactly why I bought the Kontrapunkt C. I had gone from a Shure V15VxMR on a Rega P3, to the SME 10 initially with an M10 arm, then a Series V arm, then a Benz Micro Wood H2 and then the Ruby 3. Why was I unhappy with the Ruby 3? I suspect I was seduced by enthusiastic reviews, and simply got lucky that the reviews, on this occasion, were telling the truth. At that time though, I remember regarding the Kontrapunkt C as being just a bit over-detailed, and perhaps that was just a comparison to the admittedly lush Ruby 3. It seemed to me then as if it were a bit of a guilty pleasure, maybe making my records sound like the CDs that had replaced vinyl for me for around ten years, and upon which I had spent rather silly amounts of money chasing decent sound, when all the time it was under my nose in all the LPs I never threw away. I was using an all Quad tube system then, along with their electrostatic speakers. I still do, although the 24p phono stage has been swapped out for the NuVista Vinyl. I have no desire to change anything there: it may not be perfect but after all these years it makes the sound I regard as 'right'. I have discovered how to take apart my 2905 speakers and keep the failing panels alive a bit longer with hot glue. It's a relief on one hand to have a system that I feel content to live with for as long as I can, but on the other hand it is a responsibility to maintain those parts like cartridges and speaker panels that wear out. Listening again to the Ruby 3 recently, I was pleased to find it competitive to the Deccas. Not as close as the Ortofon, but nonetheless, pretty good. I haven't seen fit yet to dig out the Wood H2, but maybe I shall once I have carts on the Rega RB330 arms and have 309 headshells to spare. Just for fun. It was a high output MC, and I have no reason to think it would be better than the Ruby 3 that replaced it, but you never know!

To get a bit fanciful, I see a consistent thread in the cartridges I like. Cutting the mass that has to be moved by the stylus/groove engine right down to the bone. The Deccas do it by taking the signal from the armature just above the stylus. (I've never heard one, but I dream about the old Ikeda MC designs that did the same.) The current MI designs have a cantilever but claim to have as little mass on the proximal end as possible. Lederman gets quite poetic describing that, and I think he is right in principal, but not all the way there in execution. I haven't heard a Hyperion, though. Now to take that as far as we can, there are new cartridge technologies that look promising: the strain gauge, where the proximal end of the cantilever doesn't have to move, just press against the gauge, and the the DS optical system that needs no mass on the cantilever other than wafers that block more or less light from internal LEDs in the body. Finally, with a nod to those old Ikedas, there's the AT ART1000 with the coils mounted on the cantilever right next to the stylus (like an old Neuman DST 62). I'd give my eye teeth to have the chance to compare those three in my system. For good or ill, it seems my canines are safe!

I understand the Statement 3 belonged to the lower tier of Grado cartridges, but they felt it was sounding good enough to be promoted to the Lineage series along with the Epoch 3 and the Aeon 3. I'm very pleased to hear that the Epoch 3 does so much for you, and I assume it is very different to the Statement 3.

There really isn't anything wrong with the Statement 3, if you value neutrality above all else. But I don't hear any excitement in the music. Perhaps I'm accustomed to a highly corrupted sound from the Deccas, and I interpret that as excitement. Who knows? But that's what I'm looking to find again.

Markus,

This is what I wrote about it:

I spent three hours today looking over the shoulder of a skillful repairman as he dissected a Quad 2905. It takes about 20 minutes to get the speaker stripped down to the point where you can see and test the panels. There are six separate panels, two bass at the bottom, two mid/high range in the middle, and two more bass panels at the top. For those who don't know, each panel is a sandwich, with a plastic grid of 2cm squares on the outside front and back. Inside this is a copper panel perforated by a grid of small circular holes, resting against a phenolic board like a PCB (again, front and rear). Between the phenolic boards is a Mylar membrane, glued at the edge to the rear plastic grid's outer edge. There is a 2-3mm gap between the Mylar and the PCB in front of, and behind it. The Mylar has a graphite coating all over except for the very edges. High voltage is fed into the copper stator on each side of the Mylar, and the graphite responds by by being drawn to or repelled from the stators. The stators are solid single pieces of copper for the bass panels as low sounds are non-directional. The mid range/treble panels have the classic Quad arrangements of concentric circles of the copper mesh, each part circle connected separately through delay lines so that the two treble panels act like one large concave/convex panel, simulating a point source.

All the delay lines must be unsoldered to remove panels, and reconnected afterwards.

My faulty panel, this time, was the lowest bass panel, and the phenolic board at the front of the sandwich with the copper stator on it was detached from the plastic frame at one side. Originally, it was glued in place. Careful probing with an insulated tool makes the loose part of the stator arc noisily as it is pushed towards the Mylar. So that panel was removed and replaced with a new one ordered from Mo-Fi some weeks ago.

However, the four original panels in that speaker (two now being replaced with new ones) all have the same problem developing, and all on the same side of the front face. They have come loose from the frame, but are not yet loose enough to cause arcing. Comparing old and new panels one can see some differences. The glue on the originals is slopped around a bit, but is extremely sparse or absent where the phenolic board is loose. The new panels have a visible bead of glue connecting the stator to the plastic grid.

So we scratched our heads for a bit, and discussed various glues. We don't want water based glue, and we don't want it to penetrate through the phenolic board. We decided to place a blob of industrial hot glue at each cross of the grid, and then used a dental pick to pull the copper stator back up against the glue as it set. We used one of the old panels as a test first to ensure the Mylar would not be hurt by the heat of the glue - it wasn't. Then I remembered the roasting bags for poultry, which I think are made of Mylar, so it should resist heat OK. At the end, all the stators on the front are well-affixed to their frame. None of the stators on the back of the panels were loose at all. Looks like a poor manufacturing process led to insufficient glue, and I'm guessing Quad became aware of it since the new panels have lots more glue on them. Then the speaker was reassembled and we set off home.
It works just fine now. So what was the point of the hot glue? As the end of the stator starts to flap in the breeze it gradually detaches for more of its length, and at some point it can move enough to touch the Mylar and it arcs. After a short (pun intended) while there is a hole burned right through the Mylar. By fixing the stators firmly with glue I hope we have reset the clock on those panels, or at least at that end of them, as the other end had no looseness, and nor did the rear stator as I said above. Time will tell.

As for doing it myself if needed, I think I can. There are airtight dust screens that look like Saran wrap on the front and rear of the speaker, to keep dust out (!) - because an accumulation of dust would increase the risk of arcing. The PCB with the delay coils and circuitry on it is coated in wax, probably beeswax, as it is outside of the sealed dust screens, and again any dust gathering between the terminals that the delay lines are soldered onto will encourage the terminals to arc. So after re-soldering the delay lines we dripped a beeswax candle onto the terminals. Not as pretty as the factory finish, but it should work.

Now the other speaker hasn't had a problem at all, so far. I could take it apart now and go at it with the glue gun if needed, but I think I'll wait until it starts to cause trouble, replace the panel that goes, and apply glue to all the others if showing signs of loosening. Fingers crossed, it won't happen...

So if you are hearing a buzzing, you probably have a panel that has begun to detach from the plastic grid. Put enough energy into it when you turn up the volume and you make it vibrate, and it will gradually come loose over a longer section. Ultimately it gets so loose it comes close to the Mylar and it arcs. Very quickly a hole burns through the Mylar and the panel is toast. The hot glue serves to affix the stator panel back to the plastic frame, so that it doesn't work loose and get close to the Mylar. I wish I'd had the foresight to photograph everything as we did it. The anatomy inside each panel is hard to describe with words alone. There are some photos on this site. At least you have but four panels in each speaker to worry about: I have six!

The older Deccas often required some special voodoo to tame or obviate their hum. Some of it was related to the common ground of the three-pin versions, some because of the thin pressed metal shell. So trying various ground configurations and doing brave things like potting the innards with bees wak was tried. The Deccapod mount was made to tame the resonance too, as were some third party efforts to encase them in wood.The recent models have much less resonant shells, and have come from Mr Wright ready potted.

I'm no expert on the older Deccas, but there is as much or more information than anyone might need in this 290 page thread:

 

A DD TT with an AC motor being rather awkward. Some people have tried shielding the motor with mu-metal.

Oddly, I have never heard any hum with my Deccas, but they are of the newer type, with proper bodies and four pins. They don't seem to mind me connecting both ground leads either (though I do connect one to the phono and one to the pre-amp.

I would make a guess that the higher output Deccas (5mV typical) with more windings on their coils, would be more sensitive than lower output MI designs. I never hear complaints of hum about Grado, Soundsmith or Nagaoka.

Having heard the Sussurro MkII transformed by treating it as an MC and playing with the resistive loading, I had to do the same with the Grado Statement 3. This has an output of 1mV, which could be treated as MM or MC. I have used it as an MM, but my phono amp lets me do pretty much what I want, so...I mounted the Statement 3 on a 309 headshell and fitted it to the second SME table and aligned it with the Feickert (Baerwald). Set the VTF to 1.8g and the VTA as dead level. I like to use Elgar's Sea Pictures for the next bit, as Dame Janet Baker has a powerful contralto voice for the top end, and the tympani provide some deep bass behind her voice. So I listened to the first track, the Sea Slumber Song repeatedly while altering the resistive loading. I kept the volume comfortable with an SPL app, between 50-60dB. I have the options of 10, 25, 50, 100, 400, 800, 1200 and 47kΩ. Starting with 47k, it was rather thin with her voice a bit much for me. Coming down to 1.2k she was tamed a bit, and more so at 800Ω. I think 400 is the first loading that sounds like a real voice, and maybe I prefer the 100Ω loading. The tympani got a bit more prominent at first as I came down from 47k, but after that stayed much the same. Having done that I moved on to the next section of my torture test, conveniently on the other side of the same LP (EMI ASD655, Barbirolli, DuPré, Baker, LSO, Elgar Cello Conc and Sea Pictures). Not the world's finest audiophile LP, but the best I know of that expresses both music and sound in luscious detail). The cello is not only a wonderfully expressive instrument, but it produces some of the richest of natural timbres. If I describe the rosined horsehair bow drawn slowly over the Cats Go strings (Cats Go Down Alleys - C, G, D, A yes?) you can feel shivers down your spine as you imagine the horsehair grab and slip many times in the duration of each note. If you don't feel what I mean you should stop both reading and listening and go and watch football.
The cartridge is dramatically better than when set as an MM, and is probably more refined than the Sussurro, which has a bit of the bouncy liveliness that makes me enjoy the MP-500. I think it is now just in the lead for one the remaining seats on my tonearms. The last seat will become a Sussurro vs MP-500 showdown. Price-wise, that should be a foregone conclusion, but it seems to me that price is not a reliable guide here in the upper troposphere of cartridges (I'd place the Reference in the lower stratosphere, but beyond that I have no experience).

And after all that......GOOD NEWS!

 

Don't know who that is, nor if armatures are to be made again, but this is excellent news!