Silicone oil damps significantly. I can’t say how much it damps in the Moerch bearing since I have not seen any experiment with lateral and vertical signals neither with the DP6 or DP8 arm. My unipijot UP4 use 600 000 cst oil. It is almost solid. Have no idea what the DP6/DP8 use.
The DP-8 vertical motion is undamped. The horizontal bearing in the DP-6 and the DP-8 is a clipped ball bearing covered in silicone oil. During my visits to Mørchs production facilities I only saw one grade of silicone oil being used.
Thomas and Borchee: you will not get any answers from Mørch: he died two or three weeks ago. Requiescat.
The DP-8 is expensive (but not as expensive as the SME V), but I found it a significant improvement on the DP-6 and the UP-4.
Thomas and Borchee: you will not get any answers from Mørch: he died two or three weeks ago. Requiescat.
The DP-8 is expensive (but not as expensive as the SME V), but I found it a significant improvement on the DP-6 and the UP-4.
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If DP-8 is damped horizontally only, I expect to see the resonant frequency's behavior as following diagram.
The shadowed areas are under 20 Hz. The blue lines are the resonant frequencies I expect to see, vertical and lateral resonant frequencies respectively. I expect to see a small peak in the lateral resonant frequency because the tonearm is heavily damped in the lateral plane. However, I don't think the small peak will be completely killed by the damping as Mørch's data indicated. I also expect to see a normal peak in the vertical plane since the tonearm is not damped in the vertical plane. But in Mørch's data, there was no resonant frequency peak at all. This is why I question his method and his design.
This also leads to another problem. Some people criticize linear tonearm because of the difference between its later and vertical effective masses. The same criticism can be applied here as well. I personally think the lateral and vertical masses should be similar.
You are plotting 10-20 dB peaks in the diagram. My Shure V15Vx shows peaks of 4-6 dB depending on direction. The Moerch diagram of the vertical modulation shows a ≈3 dB "peak", and if you would change scales I am certain that you would see it more clearly.
I spoke to Hans-Henrik many years ago, and I knew he was quite old already. Sad to hear he passed away. Anyway, the 600 000 cst for the UP-4 was what I read at another forum, claimed as a direct source from Hans. At least the company seems to to continue through the family.
If you see any of the custom Ortofon OM/LM arm wands around send me a PM...
The blue lines are for illustrating purposes only. They are not real. Even though you may see a 3 dB peak in Moerch's diagram, it doesn't look like a resonant frequency at all. It extends well into the frequency above 20 Hz. The frequency is simply too flat to be recognized as a resonant frequency. I don't think it is a resonant frequency.
@ThomasA: Hans Henrik was 92 years old. A very respectable age and a life lived to the full.
@super10018:
Mørch designed the DP-8 to have different f-res laterally and vertically. You may disagree about the desirability of the aim, but the graphs demonstrate that he succeeded.
Mørch designed the DP-8 to have a controlled roll-off, both vertically and laterally (but at different frequencies). You claim that there is no f-res in the graphs because you do not see a rise in amplitude around the f-res. The lateral graph does show that Mørch achieved his design aim of an ideal controlled roll-off for frequencies under the f-res, similar to what you would see for a simple LC circuit in an electronic circuit. Compare Mørch’s graphs to this graph of a 75 Hz high-pass filter from a Mackie 1402 mixing console
As you see there is no overshoot/rise in amplitude in this filter. In fact it looks remarkably like Mørch's lateral frequency plot. There is no law of physics that says that the amplitude of a resonance must rise significantly.
Compare that (and Mørch’s graph) to this (my own measurement of DP-8 lateral resonance with SPU Royal with the blue armtube):
You may be right that damping was applied to the Kontrapunkt (but I doubt it, since Ortofon generally are very good in this aspect)
In the white paper I referred to earlier Ladegaard recommended an f-res at 15-18 Hz. For that recommendation to work, the resonance peak must be low amplitude. Mørch’s graphs show that he achieved this. he did this by providing very light and stiff armtubes and the option for variable damping (of vertical movement in the DP-6 and lateral & vertical movement in the UP-4).
You ask ''Can a silicone-damping device [eliminate the resonant peak]? and answer 'I don't think so’. In previous communications you have told us 'I don't care what method he used.’ 'I don't care if the frequency response is linear or not’ and you suggested that we disregard the results of tests when they do not correspond to what we believe they should show ('Let's assume your test is 100% correct. This is another piece of evidence that the method used by Mørch is problematic.’)
You inexplicably choose to disregard the appropriateness and evidence of the graphs and we are moving into the realm of faith rather than fact.
And, anyway, I am happy that my Mørch arm sounds fantastic and that it excels in every measure that I find relevant, be it objective or subjective.
@super10018:
Mørch designed the DP-8 to have different f-res laterally and vertically. You may disagree about the desirability of the aim, but the graphs demonstrate that he succeeded.
Mørch designed the DP-8 to have a controlled roll-off, both vertically and laterally (but at different frequencies). You claim that there is no f-res in the graphs because you do not see a rise in amplitude around the f-res. The lateral graph does show that Mørch achieved his design aim of an ideal controlled roll-off for frequencies under the f-res, similar to what you would see for a simple LC circuit in an electronic circuit. Compare Mørch’s graphs to this graph of a 75 Hz high-pass filter from a Mackie 1402 mixing console
As you see there is no overshoot/rise in amplitude in this filter. In fact it looks remarkably like Mørch's lateral frequency plot. There is no law of physics that says that the amplitude of a resonance must rise significantly.
Compare that (and Mørch’s graph) to this (my own measurement of DP-8 lateral resonance with SPU Royal with the blue armtube):
You may be right that damping was applied to the Kontrapunkt (but I doubt it, since Ortofon generally are very good in this aspect)
In the white paper I referred to earlier Ladegaard recommended an f-res at 15-18 Hz. For that recommendation to work, the resonance peak must be low amplitude. Mørch’s graphs show that he achieved this. he did this by providing very light and stiff armtubes and the option for variable damping (of vertical movement in the DP-6 and lateral & vertical movement in the UP-4).
You ask ''Can a silicone-damping device [eliminate the resonant peak]? and answer 'I don't think so’. In previous communications you have told us 'I don't care what method he used.’ 'I don't care if the frequency response is linear or not’ and you suggested that we disregard the results of tests when they do not correspond to what we believe they should show ('Let's assume your test is 100% correct. This is another piece of evidence that the method used by Mørch is problematic.’)
You inexplicably choose to disregard the appropriateness and evidence of the graphs and we are moving into the realm of faith rather than fact.
And, anyway, I am happy that my Mørch arm sounds fantastic and that it excels in every measure that I find relevant, be it objective or subjective.
Attachments
Hi Thomas,
The system will not let me send you a PM, so I am trying this way:
Are you still interested in an ICA230 arm tube (for the Ortofon LM30) for the Mørch arm. I recently bought a Mørch turntable with a UP4/ICA230. I have more than enough arm tubes for Mørch arms, so if you are interested, this ICA230 is for sale.
All the Best
maybe posted before? http://www.cartchunk.org/audiotopics/ToneArmMechanics.pdf
it explains effective mass with examples and is easy to understand
it explains effective mass with examples and is easy to understand