I'd reach out to Alfred Kayser with SME Tonearms in Ontario (Canada). He's been extremely helpful with my basket-case 3012.
Roll call, SME series 1 3009, 3012 arm's
- Thread starter totem
- Start date
totem
Addicted Member
My series 1 unmolested 3012 stub connector was a steal pin/rod inside a rubber sleeve/coupler, my early Ortofon long mono arm used the same steel rod construction
and rubber sleeve/coupler but the rubber was a different colour. The use of a flexible coupling for the stub connection was very common in early arm designs
and eventually fell out of favour as can be seen in modern arms
The teflon or other material solid connectors sold on Ebay had issues with being the correct size to mate with a given arm tube ID.
Personally a tight friction fit foregoing rubber and a pin is a modern approach.
and rubber sleeve/coupler but the rubber was a different colour. The use of a flexible coupling for the stub connection was very common in early arm designs
and eventually fell out of favour as can be seen in modern arms
The teflon or other material solid connectors sold on Ebay had issues with being the correct size to mate with a given arm tube ID.
Personally a tight friction fit foregoing rubber and a pin is a modern approach.
Well, kinda...
Arm tubes without isolators is the modern approach, but in order to get there the entire arm design has also been rethought. The original problem from the sixties was in managing the mechanical vibrations from the cart into the arm tube. A design with a back stub hung on a flexible isolator breaks up the vibration of the arm tubes's resonance frequency into two smaller ones, ideally tuned to not enforce each other at any of their harmonics. And also, the rubber provides an additional damping of the vibrations.
The downside of the design of course is that damping part, not only affecting the arm resonances but also effectively killing off transients and timing.
One could replace the rubber with something harder, as with the teflon parts, but the only result of that would be a return to the pre 60's designs, with the arm tube doubling as a resonator. In fact, many of us have first hand experience of this. It is exactly what happens when an old isolator rubber hardens by age through post-curing or oxidation. The result tends to disappoint, often causing the owners to get rid of perfectly well designed arms because of their dull or overly shrill sound.
The modern approach does not attempt to damp those vibrations, but to transfer them into the mass of the plinth / chassis of the machine. But to achieve that, the entire arm must be made much more solid, with all bearings tight enough to carry the vibrations to the next step of the path without increasing the bearing friction. Also, the vibration path must be built without any major variations of the mechanical impedances, since those would reflect a part of the vibrations back into the arm tube. This is pretty much the basics of the Series V, Ittoks and everything that's been built after that. (Apart from the ones from the ultra low mass years).
So yes, If you are willing to skip your Series 1 or 2, the proper solution is to get a modern arm instead. But in this case, I'm interested in having "my" (my client's, in fact) Series 2 sound as good as possible, which probably should be akin to how it was originally designed. From that perspective I'm pretty certain going undamped is plain wrong, but I would expect there to be some interesting effects to be had by adjusting the hardness, or contact areas, of the rubber isolator. I've always found SME's offer of only one type of Series 2 isolators a bit strange, considering them being used to tune arms of so different masses and materials. At least there should have been some variation between the stainless steel/aluminium tube, or 9 or 12 inch models.
Some of the silicone ones I'll be trying out have a very nice fit, giving a reasonable feel to the arm stub. But I must give them a good listen before giving any verdict.
Another question, for which I don't have any answer, is if the isolators should be tuned for different cartridge compliances. But I think this too could be interesting.
Last edited:
Good point. My guess is that SME was trying to hit some sort of middle ground durometer-wise with the coupling they chose in 1957-8.
Right so. I suppose offering different sets for different arms would have made their spare parts management and support for it too messy. This also would explain why all mention of the older isolators has been buried.
Another, alternative, explanation: it could be that they reached the conclusion that the actual level of damping provided by the isolators in fact isn't that critical, as long as the resonance frequencies of the two arm parts are correctly out of tune. That would imply I'm overthinking this, apart from the misfit between the S2 isolators and the ones I've got.
I may have misunderstood your question, but my rubber bumper on the arm lift (SME mushroom?) just died in my hands while replacing the damper fluid, so I'll have start making those too.
While reading up on those I found several parts you've asked for can be found at Riverside Audio. (Obviously no affiliation...)
FWIW, I bought some 5/16" XXX phenolic rod on advice from Alfred Kayser (smetonearms.com) and used that in place of the brass spigot and the too-tight rubber coupler on my Series 1. The rod is a tight friction fit in the counterweight stub and a slightly tighter fit in the arm tube, and I left a ~ 1/16" gap between the stub and arm tube to aid in mechanical decoupling. There is no sag in the counterweight stub and per Alfred, the phenolic should provide a level of isolation reasonably to the brass spigot + rubber coupler due to the fiber + resin composite nature of phenolic.
Interesting, but in technical terms this seems unlikely. As I wrote above, the entire point of the decoupled arm designs is to have the front and back ends decoupled from each other, to give the ends different resonance frequencies - not primarily "decoupled" as in isolating the vibrations between the two parts, or impeding the vibrations from the front end from reaching the back. What the SME designers wanted was an arm with two smaller resonance peaks, instead of one larger, in order to both reduce and "smear out" the resonance in the arm tube.
Phenolic is far too hard to allow for this kind of movement. What Alfred would seem to suggest would instead be a combined effect of the mechanical impedance in the plastic grommet, and the contrasting mechanical impedances between the metal tube halves and the plastic grommet. From this point of view, my guess would be that even the teflon parts would be more effective in isolating the vibrations from the front end to the back, since they at least are softer than phenolic. The big isolator type that I'm discussing here is much stiffer than the 2-part designs due to its brass inserts, but it does only have rubber surfaces in contact with the metal parts of the arm, precisely to allow the front and back ends of the arm to vibrate with more decoupling from each other.
I'd say what you've got is basically a SME arm modified to a pre-50s undecoupled design. I am not saying this sonically must be A Bad Thing. As I already hinted at, I'm myself interested in the effects of playing around with isolators of different hardnesses. I still haven't found the time to put "my" td124 with this arm to a proper test with the different variants I've made. But I would be a bit surprised if the SME designers would have chosen such a complicated decoupling design with custom built parts instead of a plain plastic insert without good reasons.
If someone is interested, I've written about the results from comparing different 3012 coupling rubbers in another thread here at AK: https://audiokarma.org/forums/index...ight-tonearm-decoupling.1062442/post-17776943
The results actually surprised me.
The results actually surprised me.
graciouslee
New Member
Thanks for posting your findings, this thread and the linked to one with the results of the rubber coupling tests are both interesting reading. I am hoping to take ownership of a series 1 3012 in the next few days, completely standard/unmodified as far as I know. I won't know what condition the rear rubber coupler is in until I receive it, in the interim I wonder, as I couldn't work out from the discussion above, whether the early series 2 referred to above is using the same coupler type as the series 1? And so would a replacement rubber coupler for a series 1 be available as a spare part?
I didn't have luck with the available rubber couplers as the diameter of the Series 1 brass spigot is too large (and, IMO, the rubber is slightly too soft to prevent end stub sag).
Neither could I... I think the long rubber grommet isolator is a Series I design, but obviously it survived a bit into the Series II era. I would expect it to have been necessary in at least the 12" models with their heavy lateral and counterweights.
All I can recommend is to have a look into your arm. If it does have a slotted screw head from the backside, it is of this old type; if not, it should be the later 2-part design. The longer model is not glued in place as the later ones, but only held in place by the tension from the screw. But the old rubber may have bonded to the inside of the tube; if so, I recommend using a hot air gun or a hair blower at ca. 100-130° to soften it.
I actually have what I hope will be the production moulds for these parts ready as I'm typing this. Hopefully, I'll have the first ones ready to sell after this weekend.
The dimensions in the 2-part isolators are quite off on the older type of arms, so they can't be used in those. Actually, I doubt that design would be adequate even in the later 12" models.
Something I learned from working on these long isolators is that I will not make any attempt at making 2-part isolators without having at least one 3009 and one 3012 at hand to experiment with. The results from our listening test were so surprising I couldn't possibly guess which materials and dimensions would be best without hearing them. And with the current prices on these arms, the best I could hope for would be to find someone local willing to lend me an arm or two to restore and play around with. And as we've seen, I'm not the fastest restorer to be found...
graciouslee
New Member
Thanks for the replies, I guess I will have to wait to see what is delivered. There is a slight chance that the arm is actually unused from new but even if that is so I wouldn't therefore assume that the rubber won't still have deteriorated, age/heat/cold/etc. may still have taken their toll.
graciouslee
New Member
I can now be added to the roll call, the postal and hifi gods were shining on me today and the postman delivered my parcel containing the series 1 SME 3012. Looks in lovely condition, will be some time before I get to try it out due to the turntable for it to go on is not yet finished. I haven't had time yet to properly inspect it but my brief look/feel when unpacking it leads me to think that there doesn't seem to be rear sag on this one, though I haven't tried this with the counterweight installed yet. I weighed the main counterweight: ~200g! I am thinking SPU will be needed at the front end to balance this one out, in the future when funds allow. Here it is as I unpacked it, sitting on it's original box/cardboard packaging,plus a picture of some of the accessories that has come with it, including new/unfitted bias hanger and weight
:
:
Good heavens! Was this hiding in a climate-controlled vault somewhere?
graciouslee
New Member
Opening the parcel was a bit like opening a time capsule, the four little wood screws for mounting the arm are still sealed in the plastic bag with the two allen keys, there was a boxed/unused later S2 headshell along with two boxed/unused P1 spacers and their screws (for use primarily with Garrard 301/401 turntables). The arm comes with a D2 Decca adaptor and original/early round grey screening can, and the solder points on the 4 pin plug that connects to the base of the arm have never been used/soldered (SME didn't supply an external arm cable and this one doesn't look to have ever had one fitted). I cannot know for sure because the original owner is deceased but according to the family member dealing with the estate, he was in a habit of buying things and not using them (audio/watches/cameras were in boxes/cupboards throughout the house) so the 3012 may never have been on a turntable. Certainly all the areas where you would expect to find grub/dust (around armlift lever and bearing pillar, especially) are super clean. It is missing the bakelite headshell I think would have originally been included, really not a concern considering everything else is so lovely.
I consider myself very lucky indeed to have chanced upon it and will certainly treasure it going forwards. Just to see this was a treat:
I consider myself very lucky indeed to have chanced upon it and will certainly treasure it going forwards. Just to see this was a treat:
Attachments
I'm trying to juggle two threads here at AK at the same time. I just added a post at the other one showing the parts I've started making: https://audiokarma.org/forums/index...ight-tonearm-decoupling.1062442/post-17813581
There I also noticed that he (Alfred at SME Tonearms) was more correct than I was about the vulcanisation. The insert is actually vulcanised, but only partially, which is very clever.
Like Mr. Spock?
