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New Cart too light for my tonearm

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Posted on September 8, 2020 at 17:25:56
TGR
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Location: No. California
Joined: March 22, 2004
 I have a Garrard 301 with a Jelco 750L tonearm. For the past 3 years I have been using a Zu Audio DL-103, which was good, but I was interested in trying something else. I heard a Kiseki Purpleheart a few years ago installed in an Electrocompaniet TT, which also uses (or used, maybe) a Jelco tonearm, and it was magic. So a few weeks back ago I splurged, and I have been waiting until I had enough time (or was screwing up my courage- one of these is right) to install it.

Imagine my surprise when I found there was no setting for the counterweight that balanced the arm, not even with the cart far forward in the headshell. The Kiseki weighs in at 7 grams, and the spec on the Zu is 8.5, although it seems as though it might be heavier than that. Being Sunday, I couldn't call the retailer I purchased this from (OK, it was Music Direct). Instead I installed a Kiseki Black that I happened to have on hand - that one weighs 11 grams and fit right in, no issues (except that the Koetsu doesn't have threaded holes, and you have to use the tiny nuts to ensure it is attached correctly. What a PITA).

I did a search on this forum, and I think the answer might ultimately be with higher mass screws. But, I was really surprised that this would even be a thing. I gave up doing my own plumbing a number of years back, because every project was full of surprises, like this one.

So...why didn't I install the Koetsu in the first place? I had it rebuilt a few years ago, just before the arrival of the Garrard - it was installed in a Nottingham Space/294. I had going through some systems issues (blown amp, which fried a speaker in turn - that was a bad day), and although I had everything supposedly back to snuff, I just wasn't trusting the sound of my system. But actually, the Koetsu sounds great - more detail, more oomph, and also highs with more presence. The removable headshell on the Jelco made installation a lot easier.

 

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RE: New Cart too light for my tonearm, posted on September 8, 2020 at 18:31:48
fstein
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Posts: 2994
Location: fstein
Joined: May 18, 2006
 Tape a penny to the front of the arm. If that doesn't work try a nickel.

 

RE: New Cart too light for my tonearm, posted on September 8, 2020 at 18:37:10
B. Scarpia
 Soundsmith has a clever set of mounting hardware with 3 different weights of screws that come with washers that grip them so it's easier to use non-threaded headshells.

The problem is the screws are only 10 mm. long so measure to know the fit. I sent mine back.

If you have a hacksaw and an 1/8" piece of aluminum plate you cam make a headshell sized piece that will weigh about 4 grams. Drill some holes for the screws. That's what I did for my 4 gram ZYX. 2.5 M stainless screws of the appropriate length rounds it out.

 

I wish that I had your problems. A suggestion. (Link), posted on September 8, 2020 at 19:29:40
viridian
 Link below:

 

RE: New Cart too light for my tonearm, posted on September 8, 2020 at 19:55:34
welly
Audiophile

Posts: 1648
Location: QLD
Joined: January 22, 2001
 There are/were two counterweights available for the 750 tonearms. The standard one according to Jelco specs) is good for carts that are 4-12gr and the other for carts 12-24gr.

According to zuaudio, a Zu modded 103 is 14gr (not 8.5).

The combination of these two snippets of information, suggests that maybe your arm has the heavier counterweight fitted? Is that a possibility?

Cheers

Welly
He hoped and prayed that there wasn't an afterlife. Then he realized there was a contradiction involved here and merely hoped that there wasn't an afterlife.
- Douglas Adams


 

RE: New Cart too light for my tonearm, posted on September 9, 2020 at 01:33:38
John Elison
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Contributor
  Since: January 29, 2004
 You can add weight to the headshell as a couple of people suggested, but that might not be the best idea. Adding weight to the headshell will increase tonearm effective mass thereby causing the arm/cartridge resonance frequency to be too low. The better solution would be to reduce the mass of the counterweight. In other words, install a lighter counterweight.

Good luck,
John Elison

 

2 options, posted on September 9, 2020 at 04:12:26
Story
Audiophile

Posts: 10426
Location: NJ
Joined: December 11, 2000
 #1 - add just enough mass to headshell to allow operation until you do.....

#2 - as Elison said, take the counter weight to a machine shop and have them drill into the backside. Weigh it before and after, reducing weight appx. 5%

Or order new weight and wait.



 

I use a dime on my Syntec S-220 when fast-spinning, it adds just enough mass to keep the stylus firmly in ..., posted on September 9, 2020 at 05:04:01
J. S. Bach
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Location: Chester, SC
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  Since: June 29, 2004
 ...the groove without any hassles.

Later Gator,
Dave
Find more about Weather in Chester, SC

 

Another (possibly easier) option..., posted on September 9, 2020 at 06:23:47
blake
Audiophile

Posts: 803
Joined: May 25, 2000
 If you have and set VTF with a tracking force gauge, remove the counterweight and then re-install it backwards on the armstub with the
VTF dial on the counterweight facing backwards.

Chances are very high you'll then be able to install the Kiseki Purpleheart without having to order the lighter counterweight. If you're mounting with aluminum screws you could also go to stainless which is a bit heavier, but I'm pretty sure just reversing the counterweight will do the trick for you.

 

New Cart too light for my tonearm, posted on September 9, 2020 at 06:51:13
Basher52
Audiophile

Posts: 119
Joined: February 18, 2016
 TGR, if you don't mind putting something between the head shell bottom and top of the cart, I have lead 'shims' with notches for the screws to pass through that should provide plenty of additional weight. Some vinyl users and cart mfg's (ie Grado) don't like anything so installed, others do not object. Let me know, we can discuss delivery options. Lastly said shim is made of lead ...- maybe not allowed in CA?

 

RE: New Cart too light for my tonearm, posted on September 9, 2020 at 08:48:21
Mick Wolfe
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Contributor
  Since: September 4, 2000
 Agreed....the stock 103 weighs about 8-9 grams. The Zu bodied 103 weighs 14 grams as you state.

 

RE: Question, posted on September 9, 2020 at 08:49:04
B. Scarpia
 Does the headshell weight increase the effective mas by a like amount? I hadn't thought of that. Adding the 4 grams I only saw the beneficial effect on the VE resonance chart.

ZYX would have been happy to sell me a 4 gm. Tin plate for $400, or a Silver one, $1,000 (gasp), they hawk as a damper between cart and headshell. My plate is on top of the headshell.

 

RE: Question, posted on September 9, 2020 at 10:13:15
John Elison
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 Those weights from ZYX are a complete waste of money. You can buy headshell weights from LP Gear $3.50. You can easily fabricate your own, too. However, I think it might be better if you could find a lighter counterweight, instead.

Good luck,
John Elison

 

RE: Oh, I made my own. More concerned with your mention..., posted on September 9, 2020 at 10:32:33
B. Scarpia
 ...of the increase in effective mass you mentioned earlier. I'm betting you have a way to calculate that and then I can go back to the VE Resonance Chart and see what's what.

3.8 gms. with the longer SS screws.


 

That's a very nice looking headshell weight..., posted on September 9, 2020 at 15:21:40
John Elison
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Posts: 23900
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Joined: December 20, 2000
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  Since: January 29, 2004
 You can easily measure your arm/cartridge resonance using a test record with the required test tracks. For example, the Hi-Fi News Test Recrod has tests for measuring arm/cartridge resonance.

Ideally, you would like your arm/cartridge resonance be about 10-Hz. It's okay to go a little lower but it shouldn't go below 8-Hz if possible. Of course, the arm cartridge resonance on my turntable is about 7-Hz and it still sounds just fine. The reason for such a low arm/cartridge resonance is that the cartridge has higher compliance than it's supposed to have. My AT-ART7 is rated at 10 x 10-6 cm/dyne compliance but they installed the stylus/cantilever assembly for the AT-ART9, which has compliance of 18 x 10-6 cm/dyne. Consequently, my arm/cartridge resonance is too low.

Best regards,
John Elison

 

RE: Question, posted on September 9, 2020 at 18:01:38
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 "Does the headshell weight increase the effective mas by a like amount?"

For the most part, yes.

For that to absolutely true the added weight would all have to be directly over the diamond.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Question, posted on September 9, 2020 at 18:25:22
rivervalley817
 that doesn't sound right Tre` ... isn't the effective mass determined by the driving force across the cantilever point, weight, and balance? it's weight in motion ... damping adjusts the parameters

no?

with regards,

 

+1 on fabricate one's own counterweight. I did this one as a temporary installation that ... , posted on September 10, 2020 at 08:59:47
J. S. Bach
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Contributor
  Since: June 29, 2004
 ...became somewhat permanent; inelegant but extremely adjustable so it stayed ...



...until I got a complete Syntec S-220:



Note: That orange item is not a 45rpm adapter although it looks like one, the spindle hole is way too large although the outer diameter is correct.

Later Gator,
Dave
Find more about Weather in Chester, SC

 

"weight in motion" ..., posted on September 10, 2020 at 09:05:24
J. S. Bach
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Posts: 9575
Location: Chester, SC
Joined: November 28, 2001
Contributor
  Since: June 29, 2004
 ...:




Sorry, I just could not resist!

Later Gator,
Dave
Find more about Weather in Chester, SC

 

RE: Question, posted on September 10, 2020 at 10:14:25
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 On the vinyl Engine's "Cartridge Resonance Evaluator" page, the weight of the cartridge and mounting hard ware is added to the effective mass of the arm in order to calculate the resonance. Adding a weight to the head shell would be (in terms of the CRE) the same as using a heavier cartridge or heavier mounting hardware.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: "weight in motion" ..., posted on September 10, 2020 at 10:16:35
rivervalley817
 that's some mass right there!

 

A quote from a different forum, posted on September 10, 2020 at 10:18:22
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
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 "As someone else wrote, adding mass to the headshell most certainly DOES increase the effective mass of the tonearm, by a factor roughly equal to the added mass, in grams. (As you move down the tonearm toward the pivot, the effect of adding mass at any point on effective mass lessens proportionately.) Adding mass to the headshell will also cause you to need to move the counter-weight further back away from the pivot, in order to counter-balance the added mass and achieve the same VTF. Doing that ALSO will increase the effective mass of the tonearm, by a factor equal to the square of the change in distance from the pivot to the center of mass of the CW, times the mass of the CW. "

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

I didn't realize that Lowes sold turntable parts. nt, posted on September 10, 2020 at 10:30:33
alaskahiatt
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 nt

 

The spec for my SME type IV...., posted on September 10, 2020 at 10:31:50
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 is 10-11 grams effective mass. That is because the effective mass of the arm changes depending on where the counter balance is.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Question, posted on September 10, 2020 at 10:39:41
rivervalley817
 no doubt, and a handy on-line tool for determining resonance

however, please see the link in re: tone arm mechanics

it's a PDF showing the formulae for calculating the effective mass of tonearm / cartridge combos ... note that tracking force etc. are taken into account because the assembly is in motion

I think you addressed the OP's basic inquiry just fine, but technically there's a bit more physics involved ... I'm not a guru on the subject by any means, but your response seemed like an over simplification

best regards,

 

Having said all that...., posted on September 10, 2020 at 10:58:03
Tre'
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Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 Here's another quote. I think the math is probably correct but the posters final point seems to be counter to what SME says, unless he thinks 1 gram is not "significant".


"So effective mass in not mass - it's inertia! In fact, even the common measurement (in metric grams) is a misconception. This is brought to you here, by the tonearm manufacturers, as a curtsy to the layman. Effective mass, like any inertia, is measured in Kg/m/s2 (that is kilograms per meter per second squared). Since we're talking very small mass here - everything is divided by 1000 and so we're actually dealing with grams per millimeters per second squared. The general em formula relationships are manipulated such that we're left with grams only - but nevertheless it's Inertia!!!. Keeping that in mind it's easier to regard effective mass for what it is.

Another misconception is the relationship between 'effective mass' and mass. If you add 1 gram to the tip of the tonearm you do not add 1 gram of effective mass to the tonearm No way Jose!. You do not add a 1/3 or a half - none of it catches here. So, how much do you add? Well, that cannot be described in English, it can only be described in a math equation. This is what it looks like:

M(kg) = m(r²/L²) + (Z/3)

m is the counter weight mass
r is the counter weight distance from the pivot
L is the effective length (pivot to stylus tip)
Z is equal to twice the mass of the front end of the tonearm at the effective length. Your headshell mass is part of 'Z'.

M is the effective mass and the whole thing is in kilograms but it doesn't matter. This is just to demonstrate why the relationship between mass and effective mass is not as straight forward as one might think.

L (the leverage or effective length) will affect the importance of the real estate the most. In other words - the tip of the tonearm is the most strategic location where mass can affect inertia. Adding just a tiny amount of mass to that specific location might, just as well, be equivalent to the total effect the counterweight has on the effective mass of the tonearm. It's that important! This is where 'r' vs 'm' in the formula kicks in.

Having said that... movements of the counter weight back and forth across the back of the tonearm seldom changes effective mass by any significant amount. It's typically punched in and pre-calculated into the specs of the tonearm and it's a generic part of the given effective mass."

I added a 3.5 gram weight to the top of the head shell on my SME to get the resonance down. It made a large difference in the sound.

I could measure the resonance frequency, then take it off and measure again. That would show how much effective mass was really added.

I probably won't. I'm too lazy. :-)

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Having said all that...., posted on September 10, 2020 at 11:22:06
rivervalley817
 'added a 3.5 gram weight to the top of the head shell'

well we've certainly seen lots of coins taped to head shells 'back in the day' ... at least I have anyway

so, the guys at 'Cart Chunk' advocate for measuring in dynes rather than grams with inertia already accounted for ... but one second for disc playback covers a lot of record grooves ... yeah it's complicated and I'd rather not go through the math either ... which is why the on-line calculator you linked to is so valuable

best regards,



 

My local hardware store! )MT(, posted on September 10, 2020 at 12:50:42
J. S. Bach
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Posts: 9575
Location: Chester, SC
Joined: November 28, 2001
Contributor
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Later Gator,
Dave
Find more about Weather in Chester, SC

 

RE: Question, posted on September 10, 2020 at 13:04:07
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002



4.3 seems to back up my point.

"One myth that I have heard repeatedly is that to get the total effective mass, you must add the tracking force to the normal effective mass. This ^^^would be true^^^ if and only if you got that tracking force sim-ply by adding a mass ^^^right to the cartridge^^^...."

Until proven otherwise I still say if you add weight directly above the diamond, the weight (in grams) is added (directly, without reduction) to the effective mass of the arm for purposes of calculating the resonance frequency.

Adding a weight, such as the one pictured, where the weight is not directly above, but slightly behind the point directly above the diamond, then math would have to be done to determine what percentage of the total weight is added to the effective mass of the tonearm/cartridge system. Being close to the end of the tonearm makes me think that most of the weight is added to the effective mass.

Now if I turned this weight around so that some of the weight extended beyond the diamond then it would add more than it's own weight to the effective mass of the tonearm/cartridge system. That is to say, if 1.5 grams (of the 3.5 gram piece) were sitting beyond the diamond, that 1.5 grams would add more than 1.5 grams to the total effective mass of the arm. The part sitting behind the diamond would add less than it's own weight to the effective mass but not by much.

Sorry about all the words, I hope it's not too muddy. :-)


Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Question, posted on September 10, 2020 at 13:44:43
rivervalley817
 'The part sitting behind the diamond would add less than it's own weight to the effective mass but not by much'

providing the tone arm is re-balanced with the counter weight for proper tracking this would almost have to be the case I would think because it's part of the assembly as a whole and it's mass is moving in counter direction

agree?

with regards,

 

yes , posted on September 10, 2020 at 15:18:29
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
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 Adding mass at one end forces us to add a little more mass at the other end.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: yes , posted on September 10, 2020 at 15:26:15
rivervalley817
 that applies to women too ...

[did I just say that out loud?]

regards,

 

1 cent solution, posted on September 10, 2020 at 16:13:48
2chblast
Audiophile

Posts: 196
Location: Calgary
Joined: February 7, 2004
 Use double sided tape to attach a penny to the head shell as a trial. Canadian penny is 2.23 gm. You should then be able to balance the tonearm with the available counterweight.

 

:-) nt, posted on September 10, 2020 at 17:09:29
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
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 .
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Good idea!, posted on September 11, 2020 at 02:55:46
John Elison
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 If it works, you can fabricate a better headshell weight that attaches with the cartridge mounting bolts. You'll know how much weight you need by using the penny.

If it takes more than one penny, I still think it might be better to replace the counterweight with a lighter one.

Best regards,
John Elison

 

RE: I use a dime on my Syntec S-220 when fast-spinning, it adds just enough mass to keep the stylus firmly in ..., posted on September 11, 2020 at 05:11:49
BillWojo
Audiophile

Posts: 186
Location: NJ
Joined: July 7, 2017
 Look for a heavier headshell, there are many options out there. Jelco is no longer but they made a few. Also Audio Technica made some beautiful ones that weigh 13, 15 or 18 grams and feature adjustable azimuth. Taping stuff to the headshell will give you an idea of what you need for balance but is a half assed solution.

BillWojo

 

That seems really odd, posted on September 11, 2020 at 06:08:21
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 "Cartridge weight range: 4 to 12g (12-22g with heavy counterweight)"


Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: That seems really odd, posted on September 11, 2020 at 08:30:18
blake
Audiophile

Posts: 803
Joined: May 25, 2000
 Hi Tre:

TGR has the heavy counterweight. Worked fine with his 14 gram Zu.
Too heavy with the 7 gram Kiseki.

The Jelco counterweights are thicker at the end furthest from the pivot.
And narrower at the point closest to the pivot with the (very light) sliding/rotating dial for setting VTF there.

As I suggested below, if you reverse the (heavy) counterweight (this will render the calibration dial useless, plus you can't really see it LOL) it places the meatier part of the counterweight closer to the pivot, effectively, but slightly reducing its mass. You just end up having to set VTF with a digital scale, which most people seem to have and use these days anyway.

I do this with the heavy counterweight on a 750D, balancing out a 9.5 gram
cartridge that tracks at 2 grams. But I also use a slightly lighter headshell than the stock Jelco.

At 7 grams and stock headshell, there's a very good chance that this will work for the OP, costs nothing, and avoids having various coins taped to his headshell LOL! His Kiseki tracks a bit higher, apparently around 2.3-2.4 grams ideally, so the question will be whether the reversed, heavier counterweight can be moved close enough to the pivot while still allowing some space to achieve the higher tracking force. But I would think that it is at least a strong possibility.

Seems to me to be the most elegant and cost effective solution mentioned if it works, so worth a try.

 

"Kiseki Black" = Koetsu Black?, posted on September 11, 2020 at 10:40:01
Lew
Audiophile

Posts: 10911
Location: Bethesda, Maryland
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 I assume you made a typo, but it induced me to wondering about the new KPH. As I understood it, the original Kiseki Purple Heart was made by Sugano who eventually changed his company name to Koetsu. So who makes the new version of the Kiseki Purple Heart? Its output is analogous to a typical modern Koetsu, but its internal resistance is higher, and its compliance seems also higher than that of a typical Koetsu. On the other hand, Koetsu also has a boron cantilever, etc. Thanks.

 

RE: That seems really odd, posted on September 11, 2020 at 14:51:41
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 Is there no where he could get the other counter weight?

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: That seems really odd, posted on September 11, 2020 at 15:14:10
blake
Audiophile

Posts: 803
Joined: May 25, 2000
 Sure. He can by one off Ebay. The counterweight he has is almost certainly the 170 gram version. He could buy either the 128 gram or the 140 gram version.

 

RE: That seems really odd, posted on September 11, 2020 at 17:38:14
Tre'
Industry Professional

Posts: 17294
Location: So. Cal.
Joined: February 9, 2002
 The OP has the Jelco 750L tonearm.

"750L - 12″ - Standard 160g - Heavy 212g"

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: That seems really odd, posted on September 11, 2020 at 18:10:02
blake
Audiophile

Posts: 803
Joined: May 25, 2000
 Well then I guess he needs the 160 (if he can indeed establish that
he has the 212g).

Or he can go back to my initial suggestion of, at zero cost, reversing his existing counterweight to see if that solves his problem. ;)

 

RE: "Kiseki Black" = Koetsu Black?, posted on September 11, 2020 at 19:14:21
Sondek
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Contributor
  Since: April 5, 2002
 Herman van den Dungen (sp?), the man behind Ah! Tjoeb and more recently, PrimaLuna, was a Koetsu dealer in the Netherlands back in the day. He got fed up with the inconsistent quality and general PITA of dealing with Koetsu, so he spec'd out his own cartridge and found a Japanese builder for it. He called his cartridge company Kiseki.

When the LP nearly died, Herman quit the cart business. He is now behind the newly reconstituted Kiseki. I do not know who is building them for him. With the PrimaLuna tie-in, it should come as no surprise that Kevin Deal is the US distributor for Kiseki.

The Purple Heart NS is an absolutely stunning performer and value. I can highly recommend it.

 

RE: Having said all that...., posted on September 19, 2020 at 17:27:27
John Elison
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 > Effective mass, like any inertia, is measured in Kg/m/s2 (that is kilograms per meter per second squared).

Maybe not! ....Here's what the article "The Mechanics of Tonearms" says about the mass moment-of-inertia for a point mass:

.........


Consequently, the units of the moment-of-inertia would be mass times distance squared, eg., Kg * m2 or grams * mm2. Once you determine the moment-of-inertia of a tonearm about its pivot, you can find effective mass simply by dividing the moment-of-inertia by the tonearm's effective length squared, eg., I / mm2 = grams.

This means that effective mass is measured in grams. Effective mass is not the same as inertia. Instead, it's the same as the tonearm's moment-of-inertia divided by its effective length squared thereby yielding mass and only mass.

Another way to think about effective mass is if you imagine a tonearm whose mass is zero and you place a point mass directly over the stylus that produces the same moment-of-inertia as the actual tonearm's moment-of-inertia, that point mass would be equivalent to the actual tonearm's effective mass.

Best regards,
John Elison

 

"that's some mass right there!" true, and mis-tracking will be a serious problem. )MT(, posted on September 20, 2020 at 11:30:07
J. S. Bach
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Later Gator,
Dave
Find more about Weather in Chester, SC

 

RE: "that's some mass right there!" true, and mis-tracking will be a serious problem. )MT(, posted on September 20, 2020 at 13:11:03
rivervalley817
 coupla penny's taped to the engine should improve tracking

regards,

 

RE: New Cart too light for my tonearm, posted on October 22, 2020 at 15:43:05
sktn77a@aol.com
Audiophile

Posts: 29
Location: Raliegh, NC
Joined: June 17, 2003
 Unless you have the optional extra heavy counterweight, you should be just fine with the Kiseki:

https://www.2juki.com/index.php?route=product/product&product_id=63

 

RE: Having said all that...., posted on October 25, 2020 at 02:48:49
Yeti42
Audiophile

Posts: 161
Location: Berkshire
Joined: July 12, 2010
 There are a few posts in this blog discussing cartridge matching and some measurements, I found it interesting. scroll down to the Jan 8 one to start.

http://korfaudio.com/blog

When I decided to try an SPU Royal N on my Schröder I bought the Nifi News test record to see if I was getting a reasonable resonance using the brass cartridge mounting plate on my arm. Before fitting the SPU a tested the existing combination of a Transfiguration proteus and aluminium mounting plate, the brass one adds ~5g over the ali one. With the trans I got a wobbly at 7Hz and warbling from around 16Hz and down, no visible reaction to the virticle tracks. On the face of it this would suggest that Transfiguration quoted their compliance at 100Hz but I'm not sure they do, the cartridge was 5 years old at this point.
With the SPU and brass mount in place I set the arm horizontal and the VTF to 3g with the magnet gap to the thickness of the rather thin business card I found gauged the gap to where it had sounded best with the proteus. There was again warbling over a range of tracks but only a hint of a wobble when going from the 12 to 10 Hz tracks but not on the 11Hz virticle track. I then spent a couple of weeks optimising the parameters by ear and retested This time there was a wobble at 7Hz as I saw for the proteus, which had also set up by ear.
I found the above blog when I was trying to find an explaination for what I'd observed, thier introduction of damping into the equations might hold the solution.

 

RE: Having said all that...., posted on October 25, 2020 at 03:46:34
John Elison
Audiophile

Posts: 23900
Location: Central Kentucky
Joined: December 20, 2000
Contributor
  Since: January 29, 2004
 Ortofon always measures dynamic compliance at 10-Hz. However, to the best of knowledge, all Japanese cartridges specify dynamic compliance at 100-Hz.

An arm/cartridge resonance frequency of 7-Hz is probably okay. Theoretically, it shouldn't go below 8-Hz for optimal performance, but my arm/cartridge resonance frequency is 7-Hz and it sounds just fine to me. Therefore, as long as your turntable sounds good and you don't get any cartridge mistracking, you're probably in good shape. You're also right about cantilever damping helping you achieve adequate performance from a slightly low arm/cartridge resonance frequency.

Good luck,
John Elison

 

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