[doctorcilantro]

Chrome doesn't let me post more than a paragraph, so let's try again.

I am ordering a Soundsmith Voice. I currently use a 20cu Grado with no issues, 10hz vertical resonance, on an MG1 airbearing.



Peter advised against the 28cu model which confuses me because Trans-Fi owners are use 32cu carts with what seems to be much more lateral mass.

Should the horizontal effective mass be high in order to use high compliance? I have calculated that the tad heavier SS cart and higher compliance will actually drop down my vertical resonance to maybe 8 (and the I used the calculator to estimate 10hz and test records bore this out as accurate). The effective lateral mass of the MG1 is stated at about 28g.

"Keeping the wand short reduces resonances within the arm which typically colours the music. It is probably one of the major influences contributing to the overall sound of a tonearm. Manufacturers of conventional pivoted arms go to great lengths to try to eliminate resonances. They have a hard job!
Together with a lightweight slider, Terminator has the lowest lateral inertia of ANY airbearing tonearm on the market weighing in at just over 80g including the saddle, counterweight & cartridge, allowing safe tracking of the fussiest high compliant cartridge."

[*Scotty*]

doctorcilantro,it is unlikely that a high lateral compliance cartridge is going to work well with a tonearm with high lateral mass. I suspect that you will run into trouble with records that have off-center holes. The arm will tend to stay in the same place due the high inertia is has when the groove suddenly goes sideways because the hole is off center. To a point the mass of the arm gives a stable inertial reference that the low mass stylus moves in relation to. If the mass/inertia of the arm were low enough in a near frictionless system the stylus motion would be very low to non-existent and you wouldn't generate any output voltage. Obviously not  a real world condition, but many cartridges that weigh in the 5 to 6 gm. range sound better when mass is added directly to the sides of the cartridge and the total cartridge weight around 8.5 to 9gm.
I don't understand Peters recommendation either, the MG-1 has 35% of the lateral mass than the Trans-Fi
has. If you weigh the MG-1 its mass should correspond to the claims made for it by Advanced Analogue.
Scotty

[doctorcilantro]

Scotty,

Thanks. I just posted about my desire to possible sell the MG1, but I know these unanswered questions need to first be sorted out.

Is lateral effective mass not the total weight of all moving parts (wand, weight, bearing, etc.)?

Vic says his is one of the lightest at 80g.

Analogue Audio may have meant 28g w/o the counterweight. Off to check now.

[*Scotty*]

By my reckoning the lateral mass equals the total weight of the arm/cartridge combination as there is no rotation of the tonearm in the horizontal plane. The vertically moving mass in the system could by approximated by subtracting most of the weight of the hollow tube which runs on the air manifold from the total weight of the arm tube and the counter-weight assembly. With your ability to directly measure the vertical resonant frequency the actual vertical mass can the compensated for by altering your tonearm counter-weight or adding mass directly to your cartridge.
Scotty

[*Scotty*]

doctorcilantro,
What pressure are you running your tonearm at?
Also have you experimented with higher pressures above that which is recommended by the mfgr?
Scotty

[doctorcilantro]

I'm just using the Alita? pump now, it's got quite a bit of flow. I'd guess at least 5psi?

I weighed the upgrade arm with everything except the cart, so adding that it is about 65g. The counterweight and majority of the actual bearing are on the scale; the only thing is the wand, which while connected, is sticking out.

[*Scotty*]

Well there you are, a 40 gram discrepancy, you are still 20 grams to the good compared to the Trans-Fi at 80 grams. If you give Peter the hard weight data he might change his recommendation in favor of the higher compliance cartridge. What are the sonic advantages to the higher compliance version of the cartridge vs. the medium compliance cartridge? Also has Peter mentioned any failures of the ruby cantilever
while tracking highly dynamic passages? This was actually a fairly common problem with the Dynavector Ruby 23R.
Scotty

[doctorcilantro]

I'll have to let him know my findings. Trans-Fi owners are using really high compliance carts according to Vic.

I know he was worried about possible damage to the cantilever so your mention of the failure is interesting.

I'm very interested in the Trans-Fi, which would allow easier use of an outer ring, and the very short wand.

[*Scotty*]

My vote would be in favor of the MG-1. From the pictures of the two arms it appears that the Trans-Fi has a conventional bearing for the vertical arm motion and an air-bearing for the lateral motion. I like the idea of near zero friction for both axes of motion and the fact that you have a captured air-bearing on the MG-1 as well as a damping trough.
  Raising the pressure on the arm and stiffening the bearing might give you better information retrieval. As I mentioned in my post in the other thread I am running a Gast pump. I can raise the pressure to over 40psi. and still have plenty of air  volume. I put almost  $600 into the air supply system I put together 11 years ago. I have two 60in.tall by 6dia. accumulators, an in line pressure regulator and bleed off valve and a proportioning valve to feed air to the platter and the tonearm. You haven't mentioned having an accumulator in-line to the arm to filter out any air pulsation that the pump may produce, if you don't already have one, adding one should give you better sound. Any pulsation degrades the solidity of the images in the sound-stage.
Scotty

[doctorcilantro]

Wow, what arm are you using btw?

I have a small ballast tank, and since we had to move without warning to an apt., I don't have as much leeway to make a massive ballast tank.



What do you mean by stiffening the bearing? With more air pressure?

[doctorcilantro]

He has this beast on his site:

http://adanalog.com/index.php?page=shop.product_details&flypage=shop.flypage&product_id=149&category_id=10&manufacturer_id=0&option=com_virtuemart&Itemid=35

[*Scotty*]

My TT is a Maplenoll Ariadne with an air bearing platter and tonearm. The tonearm has high lateral mass,not the best design, the platter weighs about 11lbs. and is made of lead. The plinth is a composite of corian,lead and MDF and weighs about 60lbs. Check out my gallery for a photo of the TT in my bookshelf/rack.
   Your ballast tank might be enough at the pressure you are running,you don't for sure until you make a bigger one and it doesn't improve anything thus equaling a PITA for nothing.
When you increase the pressure in a captured bearing design this is the equivalent of having closer tolerance bearings. Less information gets lost in bearing play and imaging is solider and more three dimensional. It will sound like the noise floor is lower and your low level resolution is improved. My ballast/accumulators are schedule 40 PVC pipes with flat schedule 40 PVC caps so that I can stand them on end in the closet with the pump. The flat caps reduce the peak pressure I can attain in the system they are much weaker than a domed cap of the same thickness.
  They have .5 lbs/cu.ft. of polyfill in them to help damp out the pulsations produced by the pump. For all of their size they are only .65 of a cubic foot in internal volume. They wind up being a good shape to hide in the closet and not take up too much floor space. The pump is noisy enough that is must be located in another room and the air is carried to the TTwith 50ft of aquarium tubing. The long length of tubing will also help damp out pulsation in the air flow.
You could easily put a 75ft. coil the tubing on the output of ballast tank and help suppress any remaining pulsations that the ballast tank didn't take out.
Scotty

[doctorcilantro]

The pump I have:

- Voltage: (V) AC 115 (AC 110/115/120 or AC 220/230/240)
- Rated Pressure: 10 kPa (1.4 psi)
- Rated Performance: 20 lpm (0.7 cfm)
- Rated Input Power: 26W
- Sound Level: 29 dB
- Weight: 2.4 kg (5.4 lb)
http://www.aquacave.com/alita-al15a-linear-airbr-pump-1020.html

[neobop]

I am ordering a Soundsmith Voice. I currently use a 20cu Grado with no issues, 10hz vertical resonance, on an MG1 airbearing.

Peter advised against the 28cu model which confuses me because Trans-Fi owners are use 32cu carts with what seems to be much more lateral mass.

Should the horizontal effective mass be high in order to use high compliance? I have calculated that the tad heavier SS cart and higher compliance will actually drop down my vertical resonance to maybe 8 (and the I used the calculator to estimate 10hz and test records bore this out as accurate). The effective lateral mass of the MG1 is stated at about 28g.

I couldn't get through all the posts on this thread, but perhaps I could be of assistance.

10Hz res fr is considered perfect. Recommended range is 8 to 13Hz.

Eff mass should be low, whether horiz or vert, to use a high compliance cart. You know this, I'm sure. What would work on a Black Widow (3 or 4g arm), a high compliance MM or a stiff MC?

Effective mass is NOT the sum of the mass of all the parts of arm/cart. You add cart/screw mass to Eff mass for res fr Estimates. Total mass is a non sequitur for this consideration. Both arms and carts can have different compliance horiz vs vert plane. If the horiz eff mass of the MG-1 is 28g (heavy), then for res fr calc, you would want a stiff or low cu cart for optimal performance. I suspect that an air bearing acts as a damper, much like a silicone damper, in the horiz plane. That's why a relatively high cu cart can be used on a Jelco 750, for example. It's a 20g arm, but the damper effectively......

Bottom line - Performance is ideal with the Grado (20cu/10Hz). The SS 22cu version is more appropriate. It's also more appropriate for a wider range of arms. Peter knows what he's doing.
neo

[*Scotty*]

The air bearing has effectively NO horizontal or vertical friction, the only resistance to motion is that of inertia in the horizontal or vertical axis. This is why you so frequently see damping troughs included in the design.
  I level my table in part by using the tonearm with no tracking force applied, when it shows no tendency to drift from left to right or right to left I know the X axis is leveled. The front to back or Y axis is leveled with a spirit level.
As stated earlier in the thread the total horizontal mass of the arm has to be taken into consideration when the lateral resonant frequency is concerned. When a lateral force is applied to the tonearm from a record with an off-center hole that force is applied to the entire arm in the horizontal plane. Only linear motion is possible in the X axis.
Scotty

[doctorcilantro]

Peter is worried about damaging the cantilever; maybebecause it is ruby?

The res. Freqs arent much different between 20, 20, and 28cu....so the question is given how an airbearing works, and adding some fluid damping, is the fear of cantilever damage unwarranted given that a 20cu cart works flawlessly in my current setup.

The cart weights are very similar. People are using Shure Ultras on the Trans-Fi.

I'm making a big investment on the Voice and if I can step performance up a notch at no cost with higher compliance,that would be great.
 

[*Scotty*]

If you are running the trough and your total mass is lower than the Trans-Fi I can't see why you should have any higher a risk of cantilever damage than the Trans-Fi owners.
  Yes,because it is a ruby, rubies don't bend they break. He may give you specific instructions regarding the trough set up and damping fluid viscosity with regards to his cartridges. I don't know enough about the Voice cartridge to comment further on it's compatibility with your arm.
Scotty

[neobop]

You guys aren't making a whole lot of sense. Lateral mass and lateral friction are 2 different things. Didn't you say that horiz eff mass was 28g?

I assume you're talking about the Ultra 500? Dynamic compliance is 20cu same as a V-15V. The VN5MR is the alternate replacement stylus. Perhaps 32cu is static compliance? What makes you think high compliance is better?

Peter makes those carts under license from B&O. The orig carts were designed for the ultra low mass B&O arms. The 28cu versions are for low mass arms. That's a high number for dynamic compliance. Probably the highest of any cart being produced today. Ortofon makes carts that will track up to 100 microns, with lower dynamic cu. What's the point?
neo

[*Scotty*]

Lets look at this from an inertial standpoint. The higher the mass an object has the more inertia of rest it has as well as higher inertia of motion. In the case of the air-bearing tonearm with a high lateral mass, once it is in motion it will tend to resist a change in vector or velocity more than a tonearm with lower mass.
    The first consideration comes from a mismatch in cartridge compliance versus tonearm mass.
The particular failure mode of a cartridge with a ruby cantilever involves a lateral or vertical acceleration of the stylus that places a stress on the cantilever which surpasses the ruby's beam strength. This can occur if the inertia of the tonearm prevents the arm from following the groove modulation. Theoretically the tonearms motion should only involve a constant velocity towards the center of the record, in actual fact it wiggles back and forth trailing the stylus motion,this is the tail wagging the dog as it were. Ideally the tonearm should provide a fixed inertial reference in relation to the stylus motion so that any acceleration of the stylus by the groove wall results in a corresponding electrical signal with no loss of amplitude due relative motion of the cartridge . In the real world the cartridge motion trails the stylus motion induced by the groove wall this accommodation helps the stylus stay in the groove at the expense of tracing accuracy,this is a necessary compromise for real world operation.
When the mass of the stylus and cantilever is lowered and the compliance is raised there is less of the tail wagging the dog,however the cantilevers mechanical limits of motion are more easily reached and when exceeded snap goes the ruby. Damage of some kind can occur anytime there is a gross mismatch between cartridge compliance and arm mass regardless of the type of cantilever material used.
  The other lateral mass problem that can occur comes in when a record with an off center hole is introduced into the equation. The mass of the arm in combination with the lateral compliance or spring rate of the cartridge suspension forms a resonant system. When the off center hole in the record introduces oscillation into the resonant system
the frequency of this oscillation may correspond to the resonant frequency of the tonearm/cartridge combination. When this happens elementary forced resonance occurs due to the application of an external periodic frequency that matches the natural resonant frequency of the arm/cartridge system. The end result being ever increasing amplitude of oscillation in the system until structural failure of the phono cartridge suspension occurs. Adding damping to the system will prevent the runaway oscillation from occurring in the first place.
  The damping trough can cure the undamped oscillation problem but it won't cure a fatal mismatch between cartridge compliance and arm mass.
Scotty

[neobop]

Scotty,
That's not what doesn't make a whole lot of sense. High lateral mass is a problem with most air bearing linear arms. What I don't understand is the desire for for the high cu cart, and the insistence that it's better.  Especially in this situation, it seems extra inappropriate. As you said previously, a damping trough should take care of it. Isn't the Trans-Fi even heavier laterally? The Shure Ultra has a beryllium cantilever. Beryllium is brittle too, probably more so than ruby.
neo