Anybody got any experience with 12" arms?

[Eoin]

Thinking about an idler drive project. Bit far down the line, but I'm wondering if anybody's got any experience of using 12 inch arms? I've read the Internet bumf, lower tracking distortion, higher mass, reduced stiffness and obviously higher cost.

I could plan a plinth that'll take a large arm, anybody here tried one? Thinking I suppose of a modern SME arm in some form, also there's the Jelco one which is reasonably priced.

[crofk]

I have 2 Jelco 12" and an SME 12". I use the Jelcos on a Thorens TD124 and one on a Garrard 301. The SME is on a Technics SP10. I'm happy with them, they work well for me. Don't quite know what you are looking for if you have researched them yourself. You do need a bigger plinth if you use one. So be sure to take that into account.

kc

[Eoin]

Thanks for the reply.

It's to be a DIY replinth of a Lenco idler drive deck with attention paid to the motor, bearing and idler wheel.

Given that it's a custom plinth, the choice of arm is effectively 'free' so I can choose a 9,10 or 12 inch arm.

Not having done my geometry homework yet I am assuming that the mount point for these arm lengths will be very different. So unless I use a large arm board which can be changed then arm length will be a key consideration.

So I guess what I mean is, if you consider a 12" arm over a 9" arm is it always better, might be better but not worth the extra money, just different or 'depends'? The theory is one thing but I was hoping for some direct experience to perhaps say something like,'12" arms are better, If you are able then consider it' or maybe,'lots of money and there are downsides, be careful'.

For example, if I looked at the current modern SME range a normal 9" 309 model can be had for about £1000, a 12" 312S about £1600, and I suppose a used 9" IV or V might be got for about £1500 give or take. I'm not saying I'd use SME but they provide a range of 9&12" arms by way of comparison.

[cafe latte]

Here is a link to my idler project (Commonwealth). I decided after much consideration to go 12 inch for few reasons, first with the massive plinth I made it just looked better, second I was thinking to go Jelco anyway as they are amazing value for money and the difference in compliance is not massive and with the oil damping in the Jelco you can use carts a bit outside there compliance anyway. Also on a project like this you really want a moving coil cart which is happer on a heaver arm anyway.
Here are my links, if you have any question on building the plinth let me know.
viewtopic.php?t=34547
viewtopic.php?f=18&t=40784
Regards
CL

[J.D.]

It might be said that generally any user who's going to the effort and expense to restore and replinth a classic turntable (whether idler, direct or belt)-- is going to want to consider a twelve inch arm.

Same sort of thing, really. Like the table, this kind of arm isn't necessarily convenient, or plug-and-play simple, or stylishly 2012-looking ... but it is likely to be better, offering performance gains on what's currently available as 'stock' equipment.

From what I have owned and what I have read on the topic, any good-condition classic arm (Sme, Ortofon, Fidelity Research) and any currently available upmarket arm-- Ikeda, Sme, Orto, Moerch, Jelco-- is going to offer better performance than the nine-inch variation, assuming good setup. These companies are not in the business of offering questionable gear, so the standard "not as rigid" excuse just doesn't come into play with a perfectly functional unit. Even the other standard, "too much mass" isn't necessarily an issue, given that MC carts, as mentioned above, generally require increased mass.

So any of the top-shelf twelve-inch arms, if fully functional and well-matched to cartridge, is going to have the odds in its favor over the shorter ones. The end result of the twelve-inch edge on tracking is a more relaxed, fuller and more openly natural sound all the way through the Lp side, rather than any sense of confinement at the off-nulls, a feature of the shorter arm.

I'd offer that this is not one of those audiophile I-think-I-hear-it improvements. If you are thoroughly familiar with the performance of your Lp setup, you'll hear it clearly in one side of one record. This is also the kind of thing that is most noticeable when you have to go back to a shorter arm; there is always a more congested feel at the off-nulls with the short arm.

You might also notice as you look at the literature that the most immediate dismissal of the twelve-inch arm generally comes from owners or manufacturers of tables that could never accomodate a long arm anyway.

For my part, I regard the nine-inch arm as a concession to convenience over performance, something that a no-holds-barred project will not settle for. If you're already playing Lp Records, and on gear you've built or modified yourself, perhaps thru tubes, transformer-volume-control, Lcr-phono, and the kinds of esoteric speakers we tend to use (ie, not Polk or Bose)... you're not going to settle for the higher tracking penalties associated with short arms.
J.

[AudioSoul]

I have owned the Jelco 750D 9" and 750DL 12" arms and I like the looks and added convienience of being able to use a widder variety of carts.. I have used both of these arms with a DL-103R with great effect. The 103/103R carts. do sound better with a heavier arm though.The 750D and 750DL were on seperate TT's at different times so I don't have any direct comparisons....

[Eoin]

Thanks for all the replies. Thanks J.D. for your long write up and thanks CaffeLatte for the offer of help on the plinth. I will likely take you up on that.

Looks like a big arm will work then.

CaffeLatte, I'll read through your build thread although I read it at the time. Anything you'd change about how you'd tackle the project if done again? On the Lenco, it looks like if desired replacing the entire top deck with a laser cut steel replacement top plate is a (reasonably) cost effective way of doing it which which means that cosmetic restoration of the deck won't be needed.

For the plinth, many seem to be having sucess with a solid slate plinth which can be worked with domestic power tools. MDF or good quality plywood seem common alternatives.

However a further option is to get a slate plinth cut by a water jet to a design. This might actually be a cost effective way of doing it (I haven't got a router and so on so I'd be buying tools). There seem to be local companies that cut tiles to design by water jet so I don't think it's particulary expensive. Looks like the Lenco motor can be easily stripped and refurbed and setup, the idler wheel ditto or replacements are available (or I can make one). The bearing has a number of easy tweaks and refurb options or using a custom too deck opens up possibilities for aftermarket bearings.

I
Caffe, based on your commonwealth experience do you think a good idler like a Lenco will achieve a high standard if carefully done? I'd like a very nice turntable indeed if I can, is the £££ and the work justified for it?

[cafe latte]

Thanks for all the replies. Thanks J.D. for your long write up and thanks CaffeLatte for the offer of help on the plinth. I will likely take you up on that.

Looks like a big arm will work then.

CaffeLatte, I'll read through your build thread although I read it at the time. Anything you'd change about how you'd tackle the project if done again? On the Lenco, it looks like if desired replacing the entire top deck with a laser cut steel replacement top plate is a (reasonably) cost effective way of doing it which which means that cosmetic restoration of the deck won't be needed.

For the plinth, many seem to be having sucess with a solid slate plinth which can be worked with domestic power tools. MDF or good quality plywood seem common alternatives.

However a further option is to get a slate plinth cut by a water jet to a design. This might actually be a cost effective way of doing it (I haven't got a router and so on so I'd be buying tools). There seem to be local companies that cut tiles to design by water jet so I don't think it's particulary expensive. Looks like the Lenco motor can be easily stripped and refurbed and setup, the idler wheel ditto or replacements are available (or I can make one). The bearing has a number of easy tweaks and refurb options or using a custom too deck opens up possibilities for aftermarket bearings.

I
Caffe, based on your commonwealth experience do you think a good idler like a Lenco will achieve a high standard if carefully done? I'd like a very nice turntable indeed if I can, is the £££ and the work justified for it?

No I dont really think I would change anything that I did. I think the most important part of the restoration is the actual turntable. I spent a long time trying to eliminate as much noise as possible before the turntable went anywere near being fittied into a plinth. I had mine up on boxes (make sure it does not fall off though) and I listened to the chassis with a stethoscope for rumble. I found the main bearing and idler bearing to be big sources of noise. I spent ages cleaning and recleaning the main bearing and I replaced the idler bearing. I also replaced the motor rubbers as they were hard so transmitting noise. I dont think it is a good idea to make an idler tyre as i tried this myself by putting an o ring round the idler wheel, but o rings are made in a mold so are not perfectly round so they thump as they go round. My ider is a large rubber tyre so I eventually machined it to get to the soft rubber and ensure it was perfectly round. Not sure slate is a good plinth material speak to Cats squirrel on materials , he is also a bit of an expert on Lencos too. I think a well restored Lenco will be a fine turntalble as long as you spend the time to get the basics right.
Regards
CL

Edit.. Ikea used to do a wood block work surface that IMO would make a fine plinth it you glued 3 pieces together.

[KenCalgary]

I'm also thinking about a Lenco project (also to be finished way down the line) so your question will hopefully answer my questions as well.

[Eoin]

Many thanks again for the replies.

CaffeLatte. Great tip on sorting the deck noise first. If the bearing makes a fair bit of noise then maybe that'll need some attention. To be honest it doesn't look like the best bit of the deck, it's not very deep, there's a pretty poor arrangement with a circlip and a small metal disk to hold the bottom ball bearing and the spindle while fine has a cup arrangement on the bottom rather than a flat polished end so basically lots of room for improvement.

Luckily my watchmaker neighbour has developed an interest, particularly when he saw some of the worthy efforts people had already tried, he thinks he can improve and doesn't think that doing a very good bearing looks particularly difficult. Plan looks like doing a steel sleeve bearing housing as normal, using a plug threaded into the bottom for the base. On the lower bearing he suggests as per watch an clock practise using not a ruby ball on a steel surface but a ruby disc and a steel ball bearing on top followed by a polished flat bottomed spindle. I though the hardened steel spindle looked hard to make but he reckons not and says that silver steel can be hardened and polished as needed. For the radial type location he suggested as normal bronze sintered cylinders which are available cheaply in any size you like. The trade name of these is Oilite.

The top of the spindle is a precise taper to fit the platter, but again 'not a problem'. Well I wonder if a larger dimensioned bearing overall will help noise or not?

[cafe latte]

The Commonwealth bearing it quite a big bearing and runs perfectly quiet. It is a spindle it a tube as you described with a ball bearing at the bottom. The only difference with mine is rather than a bronze sleeve, mine is lined with white metal (the tube has the coating not the spindle). I am not sure how much difference this difference will make to a quiet running bearing though. I experimented with a few different oils and I settled on the quietest combination of spndle oil which is compressor oil, but a little grease on the ball at the bottom before putting the oil in. If you do use a bronze sleeve make sure you use spindle oil as normal oils have additives in that block the porous bronze and it will not work as quietly as it can. Also dont be disappointed if you use the bronze at first switch on. When I replaced the bronze bearing on the idler it took several days of oiling and playing for the bearing to wear in and become quiet.
Keep us updated how it all progresses
Regards
CL

[Eoin]

Ok no probs.

Lots of dire stories about very very tight tolerances being needed but frankly ultra tight tolerances is his stock in trade. I beleive 'stock' silver steel rod already comes very tightly toleranced, looks like you polish it and possibly the bronze bearing is lapped in.

What sort of dimensions is the commonwealth bearing?

[cafe latte]

Ok no probs.

Lots of dire stories about very very tight tolerances being needed but frankly ultra tight tolerances is his stock in trade. I beleive 'stock' silver steel rod already comes very tightly toleranced, looks like you polish it and possibly the bronze bearing is lapped in.

What sort of dimensions is the commonwealth bearing?

The shaft is 81mm long including the small ball bearing which is in a small machined cup, ie half the ball is visable. The shaft diameter is 15.81mm. The housing is a bit hard to measure without taking stuff apart, but the bottom of the housing is a plate which screws on and in the center is a bolt and locknut so the height of the platter can be adjusted.
Regards
Chris

[Eoin]

Chris, thanks.

Thats a big bearing. Shaft sounds like nearly 5/8". And 81 including the platter spindle bit or just the bit in the bearing? Either way that's a beast. Bolt and lock but arrangement sounds handy, that was one issue I'd been thinking about.