Eminent Technology ET-2 Tonearm Owners

Dover
"Loading the tonearm with mass, as Richardkrebs has advocated, increases inertia, and as the groove moves in and out, the increased resistance to lateral movement means that the cantilever will flex more and the measurement of the groove modulation will be impaired and inaccurate.

This is the fundamental principle upon which Bruce designed the LOW mass, decoupled counterweight ET2. Richardkrebs in this thread has advocated converting this tonearm into a very HIGH Mass arm. He also advocates removing the decoupling. These alterations add 60g to the effective mass of his ET2, increasing inertia and resistance to lateral motion by over 300% compared to a standard ET2.

These gross alterations will result in destroying the inherent advantages that the LOW mass ET2 offers in
superior tracking and minimising distortion."

This is what you wrote on date xx ..... take your pick.

Repetition is the sincerest form of flattery.

The HP manifold for my ET-Two 2.0 arm arrived from Bruce yesterday. After a much easier-than-anticipated swap out of the manifolds (simple thumb-push out and in), I cranked up the regulators to deliver 17 psi to the arm and settled in for a listening session that stretched into the wee hours of the morning and much of today.

To say that the HP manifold made a significant sonic improvement would be a colossal understatement. Each and every aspect of reproduction improved by a major step function. No need to specify micro/macro dynamics, impact of attack, clarity of decay, detail retrieval, low-frequency definition, warmth/richness, soundstage imaging/layering, space/air/transparency, or other descriptives. It simply improved them all and by a large margin. Night and day. REALISM!

Keep in mind that I had already recently upgraded the air supply system (Medo compressor, DIY surge tank, dual regulators, etc) and, while these were not revelatory until coupled with the HP manifold, surely all of those upgrades now contribute substantially to the overall result. I would be thrilled even had these upgrades cost 10 times what they actually did.

Many thanks to all of you on this thread, either by documenting these improvements here or by response to me directly, and especially to Frogman for providing advice, information, and the inspiration to achieve this elevated level of performance from my analog rig.

I am eager to rediscover the sound of my LP collection "as if for the first time".

Dave

Excellent! Congrats, Dave. Let me know when you are ready and I will send you the wire loom for a straight shot from cart clips to preamp to try. I think you will find that revelatory as well.

My ET spring a leak, actually one of the o'rings failed. This necessitated disassembly. I took the opportunity to give it a spring clean and weigh it. Total weight excluding cartridge was 86 grams (95 grams with cartridge). I have on loan a standard I beam, counter weight assembly (thank you Grant) this weighs in at 47 grams, excluding the spindle clamp. This would put the total weight of a standard ET2 up to 77 grams with an aluminium wand and 85 grams with a magnesium wand. It is my intention to revisit the use of a sprung counterweight. I first did this test some 16 years ago and preferred a fixed counter weight. Before I made the decision to change, I considered the ramifications of such a move. One parameter which was looked at was tracking of eccentric records. I did not want to damage my cartridge and records with the stylus slewing about in the groove.

With this issue, resonance theory saved the day.

A way back in this thread, I posted a transmissibility graph. I had hoped that this would resolve the discussion. This shows structural movement for various excitation frequencies above and below a given resonance frequency. The resonance frequency of the counterweight assembly ranges from 2 to 5 hz. The excitation frequency from an eccentric record at 33 rpm is 0.55 hz.
If we apply this 0.55 hz input to the sprung counterweight arm, we can see what happens... transmissibility approaches 1. This means that the whole structure moves. The cartridge "sees" the counterweight.
Lets put this clearly. When tracking an eccentric record with a standard ET2, the stylus/cantilever is required to accelerate sideways, 1320 times per LP side, the TOTAL weight of the arm; wand, gooseneck, spindle, cartridge, PLUS I beam and counterweights. Depending upon the counterweights used and the weight of the cartridge, this total can approach 100 grams. The same ball park as my arm.

Just wanted to add a couple of thoughts re the HP manifold. In a couple of the previous posts there appeared to be the suggestion that the HP manifold was not necessarily a worthwhile upgrade over the original LP manifold. Dave has corroborated what I have always felt: that the HP version is very worthwhile and a very significant upgrade over the LP version. After living with the LP version for several years before upgrading to the HP, I am confident that Dave's experience mirrors mine. I bring this up since the 2.5 manifold is no longer available, so this is an interesting option for all owners of the ET2 for a very reasonable price. Of course, the pump/compressor has to be a suitable one.