Trans-fi Terminator T3PRO opinions please...

A thoughtful post, Dgarretson.

Even so, I do not agree that you have demonstrated that a pump with a 1 psi output is necessary and sufficient for Terminator. First a technical quibble: as you note, P and V are inversely related, so that it makes good sense to speak of pressure at a specific load, to wit, the pressure at the volumetric load of the Terminator. I am not sure that your measurement technique accomplishes this, but have not thought about it much - is this a standard engineering technique?

Second, it seems to me that you have demonstrated that Terminator works at 1 psi (your technique), but not that 1 psi is optimal. I have measured the pressure in the line, after regulation, and this is clearly different - the saddle floats at a much lower pressure, and so my measurements are approximately 10% of yours.

My conclusions are the same as yours: just as pure DC improves amplification, pure air (pressure) improves flotation. The question arising is, what is the cost/benefit curve? Or, how heroical should we get? Since I didn't know the answer, I bought a more powerful pump so that I could waste energy in smoothing, and the results are, to me, well worth it.

Terry9 wrote "I have measured the pressure in the line, after regulation, and this is clearly different - the saddle floats at a much lower pressure, and so my measurements are approximately 10% of yours."

As I noted in my post, I too measured around .1 psi after regulation-- so on this point we agree. The 1 psi drop upstream of the regulator merely indicates how much pressure is needed from the pump to produce .1 psi at the arm. At 3 psi max capacity the Rena can make .3 psi at the tonearm. So unless you want more than .3 psi at the tonearm you don't need a stronger pump.

I believe the basic math is that at margin of air pressure necessary to float the slider, the volume of air flowing through the manifold is identical with either pump. The pressure/flow relationship is a function of the pressure drop through the system-- not of pump output. The slider doesn't care about the air flow-- only that sufficient vertical force/pressure is applied to conquer gravity. However, the pressure/volume relationship changes when you introduce a leaky tank or air line. A larger pump may be needed to make up for that loss.

I can't conceive how a leaky tank could help, unless this somehow smooths pulsing.

Hello Spirit.

Maybe I'm getting too old and grouchy ...

I agree that with all who say that the Terminator is a low pressure system, and intentionally low. The question nevertheless remains: "How low? On which turntable, with what cartridge, with what auxiliary weights?"

I thought to investigate this question. First, I bought a higher pressure, higher volume pump so that I could waste energy in smoothing. This has been VERY worthwhile, in my system.

Next, I tried to float a massy wand, comprised of a massy, low compliance cartridge, which is improved with extra weights adorning the wand. Naturally, this needs a larger counterweight. This floats, barely, at 9 mm of mercury. The sound is dramatically improved. I attribute this to smoothing.

As expected, the sound changes with pressure. Higher pressure sharpens the focus, lower pressure dulls focus. Now, the question of system integration arises, and that depends very much on the turntable.

I had deliberately softened the sound of my turntable by interposing cork discs on the shelf supports, but this appears to be no longer necessary, as I can now modulate this factor with air pressure. I will remove these as soon as I can get a mover in to lift the components, so that I can get at the supports.

Specifically, the schematic is:

PUMP --> 4 l surge tank with cotton --> regulator --> pressure gauge
--> 4 l surge tank --> 20 l surge tank
--> Terminator

YMMD

DG, I don't think that air volume is constant over a pressure change of an order of magnitude. But I have no measurements to back that up.

I agree that pump output pressure is largely irrelevant, unless you have a leaky system. Which I do - leaky tank and pressure regulator. That extra volume has to come from somewhere.

As to the leaky tank, I am pretty sure that a leaky tank smooths out pulsing. So do cotton balls. Think automobile muffler, especially like those on my first cars.

Terry,
On smoothing we must focus to get out the best of our systems. A stoopid question: does a large tank alone before the arm manifold complete this job, do we really need a leaky tank in the chain ?