04-07-13: RichardkrebsRichardkrebs – Audiogon has advised that it looks like it was double posted by the original author – that’s you Richardkrebs.
Double posts and thread ghosts of the past. How does that happen?
No ghosts involved. Is it possible that whilst sleepwalking, on the night of 07-04-2013, you reposted your earlier post of 03-30-2013?
For the benefit of readers, Richardkrebs original post reads
03-30-13: RichardkrebsThis was posted again on 07-04-2013
Dover
" self taught engineering school of fabulosity."
You go too far....
I have a tertiary education in engineering. I hold an aircraft avionics qualification and a radio technicians certificate. I teach hydraulics and electronics to paying clients.
My company employs 52 people across two countries.
We specialize in the design and building of complex servo electro hydraulics.
Recent projects have been damper doors for jet engine power stations in Oman and Iraq.
These doors, 7 meters square, are required to swing thru a 90.degree arc and stop precisely in position. Fractions of a mm are possible. The doors need to do this at both high, emergency close speeds and normal slow rates. With the multi mega watt engine buffeting it with an air stream just below supersonic.
Get the Q wrong with something as massive as this and it either fails to reach the go to point in time or it shakes itself to destruction. We usually target just below critically damped to give added safety.
My public liability does not cover destroying a multi billion power station.
I understand resonance, Q, time constants, mass damping et el.
The survival of my company and potentially the power station workers and my staff depends upon it.
You cannot begin to imagine the pre qualification process a company has to go thru to be even considered to quote on projects like this.
Compared to design work like this, a tonearm is relatively mundane. Certainly a whole lot less stressful.
I know how the ET2 works.
Richardkrebs (Answers | This Thread)
04-07-13: RichardkrebsIf this is the case, what possessed you to repeat your qualifications and work experience yet again?
Dover
" self taught engineering school of fabulosity."
You go too far....
I have a tertiary education in engineering. I hold an aircraft avionics qualification and a radio technicians certificate. I teach hydraulics and electronics to paying clients…. )
Nevertheless, thank you, you have reminded me - I do have a few observations and suggestions.
You seem to object to my observation regarding your self taught engineering. I note from your post and from your website that you encourage us to read that you have some electrical trade certificates. From your website you joined the company as a storeman, after attaining these electrical trade certificates. There is nothing on the website that suggests you have had any formal tertiary education in the fields of “engineering” applicable to the design of the ET2, specifically the physics and mathematics of this arm.
This being the case, I understand more clearly now why you have difficulty comprehending the complexity of Bruce Thigpens design.
I draw your attention to Bruce Thigpens background. After completing a business degree, Bruce commenced working for W.H.Coloney, an engineering company specializing in mechanical and civil engineering. Bruce project managed the development of the Coloney air bearing TT & tonearm ( now the Walker ). He was taught air bearing technology by qualified civil & mechanical engineers.
Bruce returned to university as a post graduate student, to study Physics, Maths & Audiology to ensure that he had a comprehensive understanding of the physics and mathematics involved in developing air bearing TT’s and tangential air bearing tonearms and the outcomes. Bruce holds many patents pertaining to air bearing tonearms and others such as patents on vacuum hold-down on records.
I studied Structural & Mechanical Engineering, Physics, Maths & Inorganic Chemistry at university in the late 70’s, before switching to Finance.
Now to the issue at hand.
For some months now you have argued that users of the ET2 tonearm should add lead mass and remove the decoupling from the I beam/counterweight assembly.
This advice on your part is in direct conflict with the set up procedures in the manual.
I quote from Bruce Thigpen:
If the weight is coupled the system resonant frequency would be extremely low, a resonant frequency at 3Hz with a significant rise in response (6-12dB) results, which would affect tracking slightly because of the asymmetric position of the cantilever, we opt for splitting the horizontal resonance frequency into two points and lowering the "Q" which improves tracking.Bruce Thigpen’s contribution affirms my statements over the past 2 months that your fixation with adding lead mass to the arm and coupling the I-beam will increase distortion, affect tracking and produce an unnatural bass lift in response. My own analysis has long been based on a thorough understanding of the design principles and physics involved.
More important than tracking, the intent was to reduce the modulation effects of low frequency energy (FM and AM) that increase distortion in the cartridge,
If you go to the Eminent Technology website and read the ET1 manual ( that’s the arm that precedes the ET2 ) you will discover that the ET2 was a design decision to move away from the high mass/fixed counterweight model utilized in the design of the ET1 to the low mass decoupled counterweight model utilized in the ET2. These new design considerations embodied in the ET2 resulted in substantive improvements in the quality of sound reproduction.
The decoupled I-beam methodology employed by Bruce Thigpen in the ET2 is designed to minimize horizontal inertia and ensure the resonance of the I-beam and counterweight remains below the horizontal resonance of the arm so that the 2 resonances ( arm and beam ) do not couple together to produce a large peak at the arms resonant frequency in the bass.
All tonearms will have a lift or peak in response at their natural frequency. The tuning with the I-beam (decoupled) is designed to reduce this natural bass peak at the resonant frequency of the arm to produce a flat bass response. This is illustrated in the graphs on Bruce Thigpen's website where he has published test results.
The addition of lead mass that you continue to advocate goes directly against the design of this tonearm.
The rigid coupling of the I-beam and counterweight that you advocate is contrary to these stated design principles.
Furthermore you acknowledged in your posts dated 03-19-13 and 03-20-13 that you have only just worked out how the decoupled I-beam works after some 25+ years of ownership.
03-19-13: RichardkrebsIn light of this newfound knowledge and your assertion that you now understand how the arm works, including the I-beam, I made a polite inquiry in my post dated 04-02-13 if you had had time over the Easter break to set up your ET2 correctly as per the manual.
It could be that tuning here with springs and weights (and their position) is at least partly to do with sorting this possible frequency interaction rather than just the weight or stiffness employed.
03-20-13: Richardkrebs
The thought that there may be more going on with the decoupled counterweight was triggered by your post where you quoted BT where he said that the ibeam had a natural frequency of 2-5 hz. ,
You have not responded. Can I assume that you have no interest in setting your ET2 tonearm up correctly?
Hi Richardkrebs
Was wondering, now that you know how the ET2 works, whether you had found time over the long Easter break to remove the lead from your arm, put the decoupling spring back in, dial in the vertical effective mass ( less lead further out for your cartridge ) and set the I Beam resonance below the arm resonance as prescribed in the manuals.
Frogman, Chris & Slaw have all found significant gains with the correct decoupling strategy employed. Frogman has reported significantly more bass information loosening off the end cap as per my suggestion some weeks ago.
I would be very interested to hear what sort of improvements you get when you get the arm back to standard configuration. ,
It is clear from your continued denial of fundamental physics and mathematics and your statements disagreeing with Bruce Thigpen and myself in the design and implementation (set up) of the ET2, your continued fixation with adding lead mass and removing the decoupling from the I beam/counterweight assembly, that you do not have sufficient understanding of the principles involved in the design of this arm.
These are fundamental principles of physics, for which you would be better placed to debate if you had some formal education that is wider than what one would infer from your posts. Anyone who understands physics would not for one minute contemplate the homebrew mods you advocate.
I quote direct from the ET2 Manual p29
ET2 Manual p29Readers should be aware that this is the exact opposite of what Richardkrebs continues to advocate. Richardkrebs is advocating increasing the horizontal inertia for low compliance cartridges – the opposite of what Bruce Thigpen recommends.
It is desirable in most cases ( low to medium compliance cartridges 5x10 dynes/cm – 20x10 dynes/cm ) to use the minimum number of weights, far out on the cantilever stem. This decreases the horizontal inertia of the tonearm while increasing its vertical inertia. ,
Richardkrebs, my recommendation for you, if you are serious about owning and operating an ET2, would be to enrol in some Physics and Mathematics papers at university. That may help you to comprehend the principles that make this an excellent arm when set up correctly.
I would advise readers and ET2 owners to ignore Richardkrebs erroneous recommendations and follow the set up procedures outlined in the ET2 manuals that can be found here.
http://www.eminent-tech.com/main.html
Frogman, Chris(Ct0517), Slaw and myself have all found significant gains with the correct decoupling strategy employed. Furthermore Frogman has reported significantly more bass information loosening off the end cap as per my suggestion some weeks ago.
My own experience with tuning the decoupled counterweight correctly and using a lower weight counterweight further out on the I-beam for low compliance cartridges as recommended in the manual yielded significant improvements in speed and articulation, transparency of soundstage and lower distortion, exactly as predicted by Bruce Thigpen’s substantive testing and published results.