[tlarwa]

Anyone have this number? I've looked everywhere. I even have the original (not photocopy) manual and it doesn't specify arm mass. Nothing on the web either. I'm trying to match cartridges, and can't use the resonance tool without the mass. Everything I read says it's a high mass arm, but what does that really mean in terms of its actual weight?

[neobop]

It's not really weight, it's effective mass which is a function of mass and distance or in this case length.

Maybe Wayner can give you an idea or the ballpark.  If it's a heavy arm, one with high eff mass then you'll need a low compliance cartridge.

Usually, there are carts known to work good in particular arms even if a compliance/mass mismatch. 

neo

[Phil_S]

Vinyl Engine lists the arm resonance at 8hz.  Does not give effective mass

[Wayner]

I don't have that info for you, but I think if you remove the counterweight and the cartridge, then weigh the arm with a digital scale, you will have your answer.

I have the 990 arm on my 598mkII, not the 980 found on the 2/398 tables.

Wayner

[tlarwa]

So the arm, pivot assembly and headshell?  What about the Dynalift assembly ... pull that off? 

[Wayner]

No. You are going to measure the weight of the arm while it's still on the turntable. You are not going to weigh the entire arm assembly itself, but how much the arm tube (and headshell) weighs from the pivots forward. You could leave in the cartridge if you know how much it weighs. So, the process is to (leaving the arm on the table), remove the counterweight, remove the cartridge (unless you know the weight), then weigh the arm assembly as it sits on the scale, at the headshell. This is the effective mass of the tonearm (whatever mass is forward of the horizontal pivots).

If you left the cartridge in, take the total weight and subtract that and you will have the weight of the arm.

Wayner

[tlarwa]

Duh ... makes sense. It'll be interesting to see how this turns out.  I'm curious if this is really a "heavy"'arm or not.  From what I've read anything >14g will qualify it as such.

Thanks, Wayner!

[Wayner]

I think it will end up somewhere on the heavy side of a medium arm. I have the Xcel sheet to do the calculations, but never did do it for the Empire, for some odd reason.

If you can, record your arm weight results here for future reference.

Thanks,

Wayner

[neobop]

Isn't that a curved arm, an S or J ?
That method is only valid for a straight tube arm.  I don't know how to calculate for tapered or curved arms.

http://www.vinylengine.com/turntable_forum/viewtopic.php?f=18&t=24136

Mark Kelly (table/arm designer) objects to this method, then retracts when he sees the limitations (p.5).

One thing to keep in mind is those calculators are only an estimate and carts often vary from spec.  Maybe if you already have a cart that might be appropriate, and a test record, you could get the resonant frequency and reverse engineer the eff mass or get close.  If this is a heavy arm You'd want to start with a cart around 15 cu (10Hz) or less.
neo

[Wayner]

Weight is weight isn't it? But most of this stuff is to get the guy into the ballpark of selecting a cartridge that is happy with the tonearm. Of course, tolerances change things, but so does an improper alignment or anti-skate setting.

Then we ask ourselves, do we hear distortions because of improper set up, or is there a compliance issue between cartridge and tonearm.

I personally don't have a lot of faith in some of the math formula stuff. While it may bridge the gap between just plain guessing and trying to mathematically prevent a purchasing error, the actual combination of cart to arm is the final judge to all the vinylphool madness (if I can use one of John, Thechairguy's quotes).

Wayner

[tlarwa]

Here's the deal.  I bought the 398 from a gentleman audiophile in Chicago who is retired, moving to AZ, and downsizing his equipment collection.  He set the table up with a Shure V15vXMR cartridge, with the original VN5XMR stylus (I'm sure he bought it new).  Now, this is by all accounts a high compliance cartridge, and in theory shouldn't work worth a damn with a "heavy" arm like the 980.  But, he ran it with the brush down (as do I) and it tracks famously and sounds absolutely terrific.  Especially running through my rebuilt Fisher 400 and Parks Audio Budgie tubed phono stage.  What I'm curious about is what the resonance is with combination, and why it sounds so much better (and tracks so much better) than it theoretically should.  Maybe the resonance is really in the correct range? 

[neobop]

Weight is weight isn't it? But most of this stuff is to get the guy into the ballpark of selecting a cartridge that is happy with the tonearm. Of course, tolerances change things, but so does an improper alignment or anti-skate setting.

Then we ask ourselves, do we hear distortions because of improper set up, or is there a compliance issue between cartridge and tonearm.

I personally don't have a lot of faith in some of the math formula stuff. While it may bridge the gap between just plain guessing and trying to mathematically prevent a purchasing error, the actual combination of cart to arm is the final judge to all the vinylphool madness (if I can use one of John, Thechairguy's quotes).

Wayner

Yes, weight is weight provided you're on Earth.  But mass and weight are not the same.  Weight is measured by the gravitational pull of the Earth on an object.  Mass describes the amount of matter that makes up an object.  Mass is measured in newtons which is a measure of force.  An astronaut in space weighs nothing, yet his/her mass remains the same as on Earth.

Effective mass is the same as moment of inertia (MOI).  This is a body's resistance to change in angular velocity while rotating on an axis. Weight and length definitely are major factors, but effective mass is a little complicated.  I don't know how close you'd come weighing a curved arm.  I think the easiest approach would be to ask other users what works.

http://en.wikipedia.org/wiki/Moment_of_inertia

neo

[neobop]

Here's the deal.  I bought the 398 from a gentleman audiophile in Chicago who is retired, moving to AZ, and downsizing his equipment collection.  He set the table up with a Shure V15vXMR cartridge, with the original VN5XMR stylus (I'm sure he bought it new).  Now, this is by all accounts a high compliance cartridge, and in theory shouldn't work worth a damn with a "heavy" arm like the 980.  But, he ran it with the brush down (as do I) and it tracks famously and sounds absolutely terrific.  Especially running through my rebuilt Fisher 400 and Parks Audio Budgie tubed phono stage.  What I'm curious about is what the resonance is with combination, and why it sounds so much better (and tracks so much better) than it theoretically should.  Maybe the resonance is really in the correct range?

The old Empire arms look heavy and I don't think you were given a bum steer.  The reason the V15 works so well on the arm is because of the brush.
The brush acts as a damper and mitigates the arm/cart mismatch.  If you put the brush in the up position and adjusted your tracking force accordingly (not recommended), you might have problems. 

In your investigations did people say what carts they were using?  We could help you figure out other carts (w/o brush) that might be suitable based on that.  I suspect most are MCs.
neo

[blakep]

That arm appears to be a bit of a beast.    It comes from the era of high mass arms; just eyeballing it I would expect it to be in at least the 18-20 gram effective mass area and quite possibly more. I'd definitely be matching it up with a lower compliance MC.

Some more information for you from an Empire afficionado on Audiokarma:


"Empire made two tonearms that went with the 208 turntable, the model 98 was introduced in 1960 and, in 1962, the model 980 tonearm. The model 98 sold in 1960 for $34.33 ($245.92 in 2009 dollars) and the 980 sold for $50.00 or $346.61 in 2009 money.

The 98 and 980 arms are high-mass tonearms; though they featured very high quality micro ball bearings in the vertical and horizontal planes that permitted extremely light and accurate tracking down to one-gram if not less, compared to other tonearms of the day. They were also dynamically balanced featuring a flat-coiled spring. This enabled them to track at any angle, even upside down. (Something I saw with my own eyes more than once.)

The implementation of the horizontal bearings also differs between the two pickup arms. The 98's horizontal bearing consists of individual ball bearings capped by a screw locked cap. This makes service difficult as you have to be careful while disassembling the arm, otherwise you'll have tiny ball bearings flying everywhere. It also makes it hard to re tighten the cap, as you have to find a balance between stiffness and ease of movement. The 980's horizontal bearings are of a captured race type that is much more service friendly with no risk of bouncing bearings getting under the rug.

The Empire 98 and 980 tonearms are very similar, and can be hard to differentiate at a glance. The main difference was the 98 has a removable bayonet pin headshell similar to the SME, and the 980 had a fixed headshell and introduced the black plastic cartridge mounting plate that existed in all Empire arms until the introduction of the model 698 turntable.

The 98 didn’t have any sort of connector to hook up a patch cord to it. It had flying leads out of the arm to solder to a suitable jack or tie points. There was also no flying fifth (ground) wire connected to the inside of the arm. Grounding was achieved from mounting the metal tonearm base to the metal base of the turntable, or by attaching a ground wire to one of the tonearm mounting screws.

No doubt part of the reason for the introduction of the 980 so soon after the model 98 was to address these small ergonomic faux pas as the 980 introduced the five-pin tonearm connecting cable (with integral ground wire) that all Empire’s had from this point on.

The 98 and 980 arm originally did not come with an anti-skate adjustment or end of record lift. Empire later offered a retrofit kit to attach a weight and pulley system to the 980 arm. Later production runs of the 980 arm featured a built in weight and pulley anti-skate system. (Seen mostly on 980 arms mated with the 498 turntable.)

The 98 and 980 tonearm were available in two versions. One for 12” maximum records, and a longer model suitable for 16” transcription discs. The longer arm was probably geared towards the broadcast industry and not for the average hi-fi enthusiast, though Radio Shack sold the 16” 98 tonearm in 1960. Existence of a 16” 980 was confirmed by two different Ebay auctions I’ve seen over the years for this longer variant.

The 98 tonearm also did not originally come with Empire’s unique “Dyna-Lift” magnetic end-of-record arm lift system, which first appeared on the 980. A separate retrofit kit was offered for sale to let you enjoy this feature on your older 98 arm and the earliest versions of the 980, which also didn’t have this feature.

The Dyna-Lift feature was unique, as it was an end of record arm lift that didn’t rely on any mechanical linkages like those on a typical record changer. It worked via a hollow cylindrical post attached to the base of the arm, which held a powerful magnet. Attached to the arm tube, near the back was a small protruding post (sometimes round, sometimes square) made of steel. As the arm nears the center of the record, that small metal protrusion enters the hole in the post and when aligned correctly, the magnetic attraction force "grabs" the arm up and off the disc as the stylus enters the run-out groove.

The action is crude and abrupt though, because being a magnet, there is no way to "damp" this action. However, I've used it for years now with a variety of cartridges and never once had an issue of damage caused by that abrupt take-off. It can also be turned "off" by pushing back on the post, which makes it cock back a good ways, rendering it inoperative. (A recent post in this thread from fellow AK'er “MrMonster” suggests the lift action is quite smooth when the arm is properly adjusted and that it is from people ignoring Empire's instructions to leave a certain set screw on the arm alone, that is to blame for the less than gentle action of most surviving Dyna-Lift examples.)

The weakest link in the 980 tonearm is the black plastic cartridge mounting plate. This alone I think is responsible for the less than enthusiastic reception given this tonearm’s performance these days. The plate is soft, bends easily under stress, and just isn’t a rigid enough platform for a good coupling of either cartridge to plate, or plate to tonearm. They are also extremely rare to find replacements for. It is a shame, because the overall build quality of the tonearm matches that of the turntable, and would mate well with any number of modern day low-compliance moving-coil cartridges that require arms as massive as these."

[tlarwa]

Thanks for all the input.  And for the record, I think I've read pretty much every thread regarding this table and arm,me it on AK, AudioAsylum, Audiogon, Audiocircle, etc.  Plus, I have all the original literature and manuals that came with the table, arm and Dynalift accessory. Not copies, mind you, but the originals!  This table is truly a time capsule, and in terrific condition! 

Regarding successful arm/cartridge combinations that I've read about, the most popular seems to be the Denon 103/103R from a MC perspective. The 110/160 is popular on the MM front.  I'm sure there's others too.  I don't have a SUT right now, so going MC isn't going to happen right now.  Maybe a HOMC?  Maybe I'll sell the Shure ... it's in great shape, with the original box and accessories.  It should bring in enough cash to afford another good MM cartridge with lower compliance.  Any other suggestions?

That said, the Shure sounds great and tracks without issue.  What danger is there in continuing to use it (brush down, of course)?

[JackD]

There is no danger. If you like the way it sounds and it tracks fine, then that is all that matters.  Sometimes the numbers and theory get in the way of real life experience.  From a practical standpoint the damping brush takes care of many of the compliance issues, if there are any.  The "Modern" Shure cartridge, the M97xe, also has the damping brush and when in use makes it a chameleon cartridge that works on almost any arm whether or not you like it's sound profile.  So if you are happy with the sound leave it alone and enjoy.

[tlarwa]

FYI... I found, on another site, that the effective mass of the 980 arm is either 17 or 18g.  That's what I'll use to try and match a cartridge moving forward.