Dear Williewonka: IMHO what you are hearing as a better/improved sound is more because you changed the cartridge/resonance frequency point that because the counterweight rear position. In the other side I can't be sure if in reality you are achieving real better sound or only different kind or even higher distortions that you like it more.
In terms of tonearm response and control to cartridge tracking grooves needs normally the best counterweight position is nearest to the pivot/bearing point not rear away.
Anyway, the important issue is not my opinion but what you like it.
Regards and enjoy the music,
What Raul says is correct. Moving the mass further from the pivot point increases the inertia of the tonearm. The Effective Mass calculation for your tonearm actually is based on inertia. So as you changed the tonearm mass in order to move the weight further out, you were changing the Fn, resonance frequency of your cartridge/tonearm system; just as Raul stated. The ideal range is around about 10 Hz. I had the Denon cartridge on my SME tonearm for a time. I had to add some weight to the headshell in order to lower my system Fn. The Denon was relatively light and the compliance put my system Fn out around 16Hz, as I recall. The tonearm was moving up and down and would even skip if the record had a slight rise/fall to it. I found a place in England on the web that sells headshell weights specifically for the Denon cartridge. It worked out nicely for me.
There are also headshell screws from SoundSmith of varying weights that can be very helpful as well.
I have read posts on other forums that also support moving the weight to attain a better sound. Further back for higher mass arms and closer to the pivot point for lower mass arms.
I do agree that adding weight/mass to my arm would bring the resonant freq closer to 10 hz, which accounts for most of the improved sound from everything I have read - that was the main reason for this exercise.
All I can say for certain is that the sound has improved for the better and as Raul said it's about the music and personal preference.
I'm not saying this approach would work for all cartridge/tone-arm combinations, but it did for mine. It costs very little and it may just sound better :-)
Dear Williewonka: +++++ " It costs very little and it may just sound better ... " ++++++
IMHO that you like it more not necessary means sound better, maybe different but I doubt seriously that that " sound better " is really better.
Anyway, as I posted what you like it is fine because you are the one that has to live with that kind of sound.
Regards and enjoy the music,
The correlation is contra-intuitive by the counterweight;
the heavier the counterweight the lesser the (arm)mass because a heavier counterweight get nearer to the pivot.
One can of course also reduce the arm-mass with lighter headshells (ususually done by FR- tonearms) but I don't like light headshells. This imply more counterweights as
some tonearms provide ( Triplanar, Sumiko 800, etc). The aim however is to get the resonance around 10 Hz as already mentioned. My Sumiko 800 has 5 counterweights meant for carts from 6 -22 g. My Triplanar has 4 but both have fast headshells while the obvious presupposition is to get those counterweights as near as possible to the pivot. In the discussion about the Triplanar however this presupposition is not accepted as a rule. One should experiment with different positions with the weights and choose the best sounding one. As is, alas, so often the case 'it depends'. I hate this expression btw.
Here is one of the sites I referenced that made me think about proceeding down this pathhttp://www.basisaudio.com/docs/tnm_vcr_mtw_specs.pdf
I'm not saying its correct - I'll leave that to the reader :-)
There is a tendency to believe that the tone arm manufacturer has done all the math for us and got it right. How could this be when in fact each cartridge you put on the arm would result in a different counterweight position.
You also have to account for cartridge design, cantilever materials etc. and their reactions to a given arm. It gets incredibly complex and there is no way any arm manufacturer could take this into account. At best, an arm is designed to work with cartridges having a defined compliance range and weight range.
I do think that it is worth investigating, given all of the arms on the market, each with different counterweight positions and some arms having multiple counterweights.
Raul - agreed "sound better" is subjective to the listener
The changes l have made sound better to me - all I am suggesting to forum readers is that trying this is not a huge expense for which they may achieve a "perceived" audible, improvement.
Without the master tapes and the original recording/playback equipment I am unable to definitively state the quality "sounds better", but improvements in fidelity, sound stage and detail I tend to quantify as "sound better"
Also, your "doubt" appears to be based on the assertion that the best position for all counterweights is close to the pivot point. However, you are not able to experience the improvements I have actually heard.
A thought - At one point in time people doubted that flight would be possible - just maybe there is something to this? :-)
Anyhow - thanks for the discussion
Dear Williewonka: +++++ " Also, your "doubt" appears to be based on the assertion that the best position for all counterweights is close to the pivot point. However, you are not able to experience the improvements I have actually heard. " +++++
things are that we already ( after 5+ years. ) finished our self tonearm design, a unique one.
Well, I respect A:J Conti as a person and audio item designer. First than all IMHO there is no perfect audio items designs that performs perfect during playback, always exist trade-offs and tonearms are no exception.
What MR. Conti stated is not only not something new but " things " that other tonearm designers already took in count. There are several tonearm designs that already made it that as: Moerch ( an unipivot design as the Vector. ), Audiocraft, Sony, Triplanar, Da Vinci, Talea MS, etc, etc.
now, what could be the trade-offs on what your linked information has?
IMHO a tonearm " exist " to fulfil the cartridge asked needs during playback and not only for hold and set up the cartridge parameters as: VTA/SRA/VTF/overhang/AS;etc but to help that the cartridge can ride/track in better way the precious information recorded in the LP grooves.
This " full " recovery of the recorded information is a TITANIC task for say the least where that tiny cartridge stylus must not only to move " freely " at random according to each one LP groove and stay always in touch with the grooves but that ( Here each one cartridge designer is the first responsable to makes its " job " for that could happen. )at " random " direction movements be/happen with the faster response by the cartridge stylus.
as longer effective lenght tonearm and as more rearwards the tonearm counterweight as worst will be the posibility to give ( the right and precise ) the cartridge stylus what it's asking, what say I? not asking but " screaming " for: the fastest tonearm response.
This is a main target, IMHO, for any tonearm design.
Try to tame the cartridge signal sound trhough adding some kind of colorations/distortions through the counterweight manipulation ( other that be near that 10hz resonance frequency that posted T.wins. ) is only that: a manipulation that IMHO does not helps to fufil the cartridge needs but to " fulfil " our imperfect " ears " with more distortionss and less accurate musical information.
My goal is to recovery the " 100% " of the recorded musical information adding and loosing the less. If what I'm recovering likes me or not it is not important what IMHO isimportant is to have the full informatiuon down there and if you don't like it instead to tame it adding more distortions/colorations analize where in my audio system chain I can improve to achieve a real better quality performance level adding no single distortions/colorations but trying to go lower in that regards.
Of course that is my main target that it is obvious you don't have. Each one of us have our each one targets and I respect yours as the MR. Conti or any one person here.
regards and enjoy the music,
in my post we can read: ++++ " at " random " direction movements be/happen with the faster response by the cartridge stylus ++++++
a mistake, it has to say:
++++ that at " random " direction movements be/happen with the faster response by the cartridge stylus/tonearm assembled. ++
Btw, of course I tested several counterweight tonearm positions and between other things that's one reason I posted what I posted.
Raul - a lofty goal indeed - I wish you every success in your endeavours and hope you achieve them. You seem to be well on the way based on your profile.
My goal - get the best sound possible from my very modest system - gauged by my own ears.
One last question - why 10 Hz - I've read various target value like 8-12 hz and several that mention 8_10 Hz
One reference stated 10 Hz was the frequency at which the arm starts to wobble. Any truth to that?
The goal of the tonearm is to provide a stable platform for the phono cartridge to track in the groove at the correct geometry. So the first order of business is to set up the tonearm overhang and alignment so that the stylus remains at the tangent point in the groove and aligned square to the groove from start to finish. Next, the tonearm is suspended over the record with near zero friction and coupled to the stylus through a spring suspension. In addition, forces are acting on the stylus in all three dimensions. The stylus is being pushed to the left and right, pulled on and pushed up and down (warps in the record). The tonearm and cartridge system is a classic spring/mass system which responds to this harmonic input. This spring mass system has a resonance point which is where small energy inputs cause large energy outputs. If the tonearm system resonance is too low, ie. less than 8 Hz, it will become sensitive to footfalls and the rotating record. The record is rotating at 0.5555Hz. 10 times that is 5.5555Hz which is a safe range away from resonance. 45 rpm puts the record rotation at 0.75 Hz so 7.5Hz minimum for the tonearm would be a safe range. Much higher than 10 Hz can cause the tonearm to become very lively with warps in the record and is also getting close to the 20Hz signals in the grooves. It may or may not skip but the lows can get muddy because the arm is responding to those low frequency signals in the record grooves. Record runout creates a 0.55Hz at 33 1/3 rpm and 0.75Hz at 45 rpm lateral sway in the tonearm. This is another reason to keep your tonearm/cartridge system response around 10Hz.
Thanks guys for all your input.
My turntable has never sounded so good :-)