Mass Effect

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phoner

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Mass Effect
« on: 30 May 2016, 10:27 am »
Aloha ,
as the WT Tonearm is very low mass (around 7g?) and the modern Cartridges are quite hard (low compliance) I wanted to know if anybody has experimented with additional mass to lower  the resulting resonances?

greetz

ADiG

Re: Mass Effect
« Reply #1 on: 31 May 2016, 08:41 am »
Which model? Those with the golf ball have 10 grams mass.
However, two counterweights are better than one because they are closest to the articulation.
There should be an thread about...

excuse the translation, but I'm Italian  :green:

threadkiller

Re: Mass Effect
« Reply #2 on: 31 May 2016, 09:29 pm »
Your translation is fine, your facts are off.
Two counterweights are only dictated by cartridge weight, nothing more.
Ciao! And happy listening over there...

ADiG

Re: Mass Effect
« Reply #3 on: 1 Jun 2016, 06:20 am »

threadkiller

Re: Mass Effect
« Reply #4 on: 1 Jun 2016, 03:28 pm »
Not that again... old wives tales.  :)

phoner

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Re: Mass Effect
« Reply #5 on: 1 Jun 2016, 04:54 pm »
Aloha,
thx for the info about WTA arm mass.

in my opinion the distance of the weight to the suspension point is a minor effect compared to the arm-resonance.

How i understand the situation:
The needle-suspension is a spring, the mass of the arm is an attached weight to this spring.
(the tracking force has not much to do with this and is adjusted independently of the charakteristics of this mass/spring system)

I imagine holding the spring and let the weight hang down...
If i start to move my hand up and down now, i can think about this as the modulation of the system throug the groove of the LP (or steps or not flat lps for that matter)

Three cases come to mind:
1. i move very quickly -  the mass stays where it is because the spring does all the moving.
2. i move very slow -  the mass (aka tonearm) is moving in unity with the movement of the spring
3. resonace: the weight starts to move wildly if i go  up/down at a certain speed -> resonance

we can not avoid this so we have to work with it
meaning: to keep the resonance in am area of approximately 8-12 Hz

 on my setup : Dyna Karat 17d3 + WTA  resonance comes clearly into the 20Hz range

i already have immersion of the golfball at 1/2 for damping and do not want to increase that more.

so the only solution seems to be adding mass to the arm to get the resonance frequeny in the desired range.
- additional arm weight (silver and black together)
- additional balast weight

the question is where to put this balast?
on the head ?
on the arm (middle/rear/front) ?


rob400

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  • Versalex and Audio Note for the rest
Re: Mass Effect
« Reply #6 on: 2 Jun 2016, 06:46 am »
Interesting I was told (not sure if it by was my dealer or importer) that using the two counterweights regardless of 'need' is preferable to one as the sound is better with the weights closer to the cup???

My Firebaugh is a genius IMO and understands turntable design better than any of us. I'm sure he considered Arm Mass at great length. Other than the A23 mat and removing the finger lift I for one have given up 'tweeking' my Versalex. I tried the XTC counterweight for several weeks before ultimately going back to the stock weights as I prefer them for long term listening (using my DV XV1s).

As a side note I've just made 2 new Baltic Birch racks as I needed an extra tier to what my Oak framed one gave me. They sound excellent. A great material as support for our Versalex/Amadeus decks and dirt cheap to buy and make by a competent woodworker. The Oak sounds 'dead' in comparison. My 2 x DV HX100's have both just been rebuilt by my Importer and are due to be returned to me next week. I will post pics when fully rigged up again...

threadkiller

Re: Mass Effect
« Reply #7 on: 2 Jun 2016, 02:20 pm »
About the counterweights... I asked the experts over here and was told not necessary, so I no longer worry about it.
Good to hear, Rob, that you're done. It's a good feeling.

I'd say most of you worry about things that are of little to no consequence.
The BIG thing is proper setup- getting the cartridge VTA and arm damping correct for your particular cartridge.
For example... big, long, rambling hubris on mass, when the poster with the 17d clearly has too much damping for that cartridge- 1/2 ball in. Everything else will now sound off. Who cares about mass when you have one of the basic audible areas wrong? And so it goes on here.

Work on damping, VTA... then mat, DPS for some, good cables, and then buy more records or fiddle with the rest of your system. Yes, a great rack even. And make sure the table is level.
Ciao!

mick wolfe

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Re: Mass Effect
« Reply #8 on: 2 Jun 2016, 03:10 pm »
I couldn't agree more on 1/2 level on the damping fluid. I don't even know how one could set proper VTF at that level....I couldn't. I've found 1/3 to be about ideal. As Threadkiller has hinted..... do a proper set-up and enjoy. The WT arm has been very accepting of any cartridge I've tried to date.

phoner

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Re: Mass Effect
« Reply #9 on: 2 Jun 2016, 05:22 pm »
lol, the guy with the sandwich as turntable can be so arrogant
he makes himself look like a little mister know it all
but when i asked him something specific about the difference between two products he could only give a very superficial and uninformative answer

there are experts where i live too and they tend to think a little different than you and your experts but that is okay, we are all cooking with water
(not that you give a damn, i know...)
regarding VTA, VTF, and damping
how would you know that i have not been there and done that (because you just know better...)

the "ramble" about mass was obviously not for you
if you can, accept that i am interested in sharing this topic (on my thread)
if not, just go away please
(no i dont need your commend about what i find interesting at all, i will ask if i want to know something from you, thanks)

so what knowledge has the sandwich guy shared with us here on my thread:
getting your angles right is very important -> thank you for sharing your great wisdom about cartridge setup mr killerknowledge

regular readers of this forum know that there is somewhat of a konsensus that 1/3 damping is just right -> dont dare to make it not so because it can not sound good, never ever and for no one...
and he also let us know that a level and solid placement of a TT is very important -> you are so right, thank you for sharing

so mr threadkiller,
if you dont have something interesting to say regarding: the topic (of my thread)
go away please
(if not, i will go away and you killed another thread, be proud of it)

threadkiller

Re: Mass Effect
« Reply #10 on: 2 Jun 2016, 07:39 pm »
I apologize for my perceived arrogance, not my product knowledge.

When I see posts such as yours, which go against everything Bill figured out for us with this great table, I post.
Your experts are not the designer nor distributor, so you lose. I merely hate to see some of you try to outthink the designer. He's a genius, you're not.

You asked for the differences between the two Auditorium mats, which I gave the findings of myself, the distributor, and my listening panel.
When your table is set up wrong to start with, how can I help you get tighter bass with mats?

Also, that's a cake, not a sandwich. Although I've never met a sandwich I didn't like, unlike certain turntables and audiophiles.


newvinyl

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Re: Mass Effect
« Reply #11 on: 2 Jun 2016, 11:50 pm »
How did you determine resonance?

According to resfreq.com resonance calculator you should be at 11.311 Hz.

Tonearm mass: 7.4
Cartridge mass: 5.8
Cartridge compliance: 15

phoner

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Re: Mass Effect
« Reply #12 on: 6 Jun 2016, 07:13 am »
no hard feelings, i just wanted to clear things up, now back to topic

I had not calculated anything so far i used a Test Lp with resonance testing tracks on it (i prefer experimenting to calculating).

But today i did the calculation with the accepted formula and i naturally got the same result as new vinyl.
But reality clearly shows that this formula seems to miss somethig.
What can be a theoretical explanation for that?

Here are my thoughts:

I read some papers on that and how i understand it we are dealing with inertia masses in relation to the pivot point of the arm.

Therefore the counterweights apply a "negative" force in relation to the inertia of armlenght and cartridgemass on the other side of the pivot!
(I guess thats where the the " mount counterweight near to pivot" notion comes from.)

-> For my next calculation i just ignored the arm mass and used just the mass of the cartridge and the result is around 17Hz which is much nearer to the reality (where i clearly come above 20HZ)


conclusions:

for me this answers the question where to mount the additional mass:
-> i will do it on the headshell

!   additional counterweight rises the armresonance frequencies because it lowers the effective mass   !

WTA owners can be happy because damping lowers the amplidutes of arm resonaces


question:

does anybody know the masses of the counterweights?
( i would like to make another calculation and do not want to take them off)

rob400

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Re: Mass Effect
« Reply #13 on: 6 Jun 2016, 05:16 pm »
does anybody know the masses of the counterweights?


Sadly I can't help you! Where is Watercourse when he's needed?

phoner

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Re: Mass Effect
« Reply #14 on: 7 Jun 2016, 02:54 pm »
I would be more interested to know if there is someone here that has actally tested the accuracy of this  formula on a WT-TT (or maybe any other):

f = 1000 : (2 x π x √ (M x C))

f - Cartridge resonance frequency in Hz
π - 3.14159265359...
C - Cartridge compliance lateral in µm/mN
M - Total tonearm system mass which is a sum of Mass of cartridge, Mass of headshell and screws and Effective mass of tone arm (all values in gram).

• Resonance frequency within 7-12Hz is optimal for the system.
• Resonance frequency slightly outside optimal interval 6,5-7Hz and 12-14Hz can be considered as a possible that probably can be used without problems.
• Resonance frequency outside the interval 6,5-7Hz and 12-14Hz is questionable, and the system might not work properly.


It seems to me that there is no factor in this formulation which is concerned with the notion that additional counterweight rises the armresonance frequencies because it lowers the effective mass....

EDIT:
well there actually is, in the M-variable, where it says:  Effective mass of tone arm

But:

! effective mass of the tone arm is not simply the weight of the arm tube !

as i understand it we have to consider the counterweight as negative factor to headweight  (cartridge+screws+ballast )
and possibly proportions in distance to pivot of headweight and counterweight

where is a mathematician when you need one ; P

newvinyl

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Re: Mass Effect
« Reply #15 on: 7 Jun 2016, 03:32 pm »
I'm not really into the math of tonearm geometry and resonance frequency, so I can't help you out with the formula. However, I am intrigued by this discussion. I never tested resonance frequently on my Amadeus; I just set it up and started listening to music. I'll get out my test record and check tonight and report my results back. To be honest, I'm expecting no resonance at any frequency.


phoner

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Re: Mass Effect
« Reply #16 on: 7 Jun 2016, 03:40 pm »
The needle-suspension is a spring, the mass of the arm is an attached weight to this spring.
-> there seems to be no way to avoid resonance, you can apply damping to lower resonance amplitudes but not eliminate it -> resonance frequency should be manipulated to a desirable frequenzy
that is where i am.

but i am looking forward to your results, it is perfectly possible that i have a fault somewhere in my TT-setup, so i am glad if we can double check things
(if anyone has the masses of the counterweights ready, please be so kind...)

newvinyl

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Re: Mass Effect
« Reply #17 on: 8 Jun 2016, 04:05 am »
Hi-Fi News Analogue Test LP
Step-by-Step: How to use this record

Side Two: Band 2 - Cartridge/arm resonance test, lateral - low frequency sweep 25-5Hz L+R, + 1kHz pilot. This is a visual as well as sonic test. If you watch the cartridge as it tracks this band, the resonant frequency of the arm/cartridge combination will be easily determined. What you will notice is that, at the resonance frequency of the combination, the suspension system of the cartridge becomes excited and a very obvious wobble is clearly visible. You will hear that the pilot tone starts to 'warble' rather than remain steady. Generally a resonant frequency of between 8-15Hz is considered ideal from a point of view of a cartridge's ability to track pressing warps and handle rumble.

Side Two: Band 3 - Cartridge/arm resonance test - low frequency sweep 16-6Hz L+R, + 1kHz pilot tone (vertical). Same test as above: but here, reversing the phase checks for behavioral consistency of the arm/cartridge in the vertical mode. Once again, a resonant frequency of between 8-15Hz is desirable. If you seem to have a resonant frequency higher than that desired, try adjusting the damping of the arm.

----------

My results for both Bands… wobble was never clearly visible and the pilot tone always remained steady. (I did each Band twice to double check.)
Maybe there was a slight wobble at 11Hz on Band 2, but it was very slight.
The reason I'm not surprised at these results is because I thought I read an Amadeus review once that indicated there would not be a resonant frequency.

To contrast these results to other resonance tests I've done, these results are completely different from those done on my previous Rega turntable. In that case, the cartridge cantilever jiggled around wildly at 12Hz - which was easy to see.

phoner

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Re: Mass Effect
« Reply #18 on: 8 Jun 2016, 03:15 pm »
aloah,
thanks new vinyl, i use the same test LP but i get very different results.

to be honest i find it astounding that your setup seems to behave exactly as the damned formula dictates...
are you shure you dont perceive just what you want to perceive?
i mean there are whole industries out there that want to, and perfectly can, make a living out of this effect and it is so natural that one has to be very, very careful about it.
so please dont be bothered if i want to stay skeptical about your statement.

visibility of armresonance om WT arms?
I have some resonance effects and it is in no case visible, neither the needle nor the arm. And i used a magnifing glass.
 so, seeing arm resonace... i dont believe in it, exept maybe in a case of "catastrophic system failure" ;)


here are my results:

lateral resonance test:
i can hear modulation of the 1kHz pilot starting at around 19Hz peaking at 15Hz dropping until 11Hz and rolling of. a very slight modulation stays for the lower frequencies

vertical resonance test:
is somewhat different, i have a peak in modulation at 20&18Hz then it all but goes away and another very low peak apears at 10Hz and rolls of again


maybe i hear what i want to hear the other way round and should not bother with slight modulation.
but modulation is modulation as well as distortion is distortion, if it is there i just dont want to ignore it.

my conclusion at this stage:
you mostly have to live with what you have bought into because all the changes in damping, counterweight mass and position are quite small.
meaning: I can (if at all) hear some effect but the basic resonance characteristics do not really change.

the most effective thing i did was adding +5g mass to the headshell 
-> i will follow this route for experimenting


here is a thread that cleared up things for me:
https://forum.audiogon.com/discussions/tonearm-effective-mass

regarding the damned formula:
Effective mass is a function of mass X the SQUARE of the distance from the pivot, so changing the distance has a larger effect than a change in mass.

-> this fact is nowhere to be seen in the circulating version of the formula, exept that M should represent exactly that but nobody seems to care and just adds some static value for arm-mass
-> therefore i wont trust any calculations made that way

Is there any one out there who can handle this mathematical problem?
(I tried but i dont trust myself on this, same goes for the scale i used)
also i still need the masses of the counterweights ( i got 25g and 70g but my scale is just 10g exact so i dont really know)

newvinyl

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Re: Mass Effect
« Reply #19 on: 8 Jun 2016, 04:58 pm »
I do not think your results are significantly different than mine. You did not see visible resonance and neither did I.

If you don't believe your own results, then there's nothing we can do to help you overcome your supposed problem.

As stated in the LP instructions, and from my own experience, the resonance frequency should be easily visible - like a spring bounciing up and down.

I think you're good to go. Don't worry about it and enjoy some music.