Chris.
Yes spring has sprung here. BBQ's, Boating, Fishing, and company with great friends watching long sunsets over a glass of wine. I suspect that it was the change in temperature that precipitated the o"ring failure.
I am using a HP manifold at around 18 psi.
HF Dover.
I knew that you would bring up the added weight question inside the spindle. The 30 gm adder was a guess based on 16 year old memory. Clearly my guess was well overstated. I will be removing this when I do the swing arm counterweight test to bring the arm as close to stock as possible. The 95 gm total, arm and cart weight, is accurate. This depending upon c/weights and cart used by others, being more or less the same as a standard ET2 using a mag wand.
For further discussion on how every ET2 on the planet requires the cartridge to push sideways the total arm weight when tracing an eccentric record, please read below....
> Bruce.
> I have been thinking about the horizontal effective mass of your ET2 and have a question please.
> The horizontal effective mass calculation you give in the tech section of the manual shows an arm mass of 30 grams which is then added to the weight of the cartridge to give total horizontal mass. This calculation ignores the weight of the counter weight since it is decoupled via the leaf spring.
>
> My question is around the horizontal effective mass seen by the cartridge when tracing an eccentric record. The resonant frequency of the counterweight spring assembly is 2-5 hz and the lateral tracing frequency of an eccentric record at 33 rpm is 0.55 hz.
> At 0.55 hz the transmissibility would be approaching 1, even with a counter weight spring frequency of 2 hz.
>
> This would therefore mean that the cartridge "sees" all of the counterweight weight when tracing an eccentric record?
> Thus the effective mass at this low frequency, 0.55 hz, would be the total weight of the arm and cartridge including the beam and the weights it is carrying.
>
> Many thanks
>
> Richard.
>
>
Richard,
Below the counterweight decoupling frequency cutoff ~ 2hz, the effective mass becomes the total mass. Then you have another resonance freqeuncy to add to the mix which is typically much greater than .55Hz.
So yes, it sees all of the mass below 2Hz, but the combination of those masses results in a cantilever resonance above that frequency. You should see the arm move back and forth with the eccentricity of a record at .55Hz as opposed to deflection of the stylus.
I hope this helps and thank you very much for the interest.
brucet
Yes spring has sprung here. BBQ's, Boating, Fishing, and company with great friends watching long sunsets over a glass of wine. I suspect that it was the change in temperature that precipitated the o"ring failure.
I am using a HP manifold at around 18 psi.
HF Dover.
I knew that you would bring up the added weight question inside the spindle. The 30 gm adder was a guess based on 16 year old memory. Clearly my guess was well overstated. I will be removing this when I do the swing arm counterweight test to bring the arm as close to stock as possible. The 95 gm total, arm and cart weight, is accurate. This depending upon c/weights and cart used by others, being more or less the same as a standard ET2 using a mag wand.
For further discussion on how every ET2 on the planet requires the cartridge to push sideways the total arm weight when tracing an eccentric record, please read below....
> Bruce.
> I have been thinking about the horizontal effective mass of your ET2 and have a question please.
> The horizontal effective mass calculation you give in the tech section of the manual shows an arm mass of 30 grams which is then added to the weight of the cartridge to give total horizontal mass. This calculation ignores the weight of the counter weight since it is decoupled via the leaf spring.
>
> My question is around the horizontal effective mass seen by the cartridge when tracing an eccentric record. The resonant frequency of the counterweight spring assembly is 2-5 hz and the lateral tracing frequency of an eccentric record at 33 rpm is 0.55 hz.
> At 0.55 hz the transmissibility would be approaching 1, even with a counter weight spring frequency of 2 hz.
>
> This would therefore mean that the cartridge "sees" all of the counterweight weight when tracing an eccentric record?
> Thus the effective mass at this low frequency, 0.55 hz, would be the total weight of the arm and cartridge including the beam and the weights it is carrying.
>
> Many thanks
>
> Richard.
>
>
Richard,
Below the counterweight decoupling frequency cutoff ~ 2hz, the effective mass becomes the total mass. Then you have another resonance freqeuncy to add to the mix which is typically much greater than .55Hz.
So yes, it sees all of the mass below 2Hz, but the combination of those masses results in a cantilever resonance above that frequency. You should see the arm move back and forth with the eccentricity of a record at .55Hz as opposed to deflection of the stylus.
I hope this helps and thank you very much for the interest.
brucet