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Old 22nd April 2012, 01:23 AM   #21
sreten is offline sreten  United Kingdom
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Hi,

Well good luck with it, your going off on tangents I never explored.

In terms of separate arms and turntables compared to integrated,
I didn't consider the 505/2 arm the major weak point, but an LVX
arm will be better, and tuning of the decoupled mounting an area
I know nothing about, not the path I chose for simple mods, as
you can't "isolate" an arm from its mounting completely.

A few points though :

1) If still using the spring suspension a plinth rebuild is not effort
effective. Damping the plinth with bitumen spray is effort effective.

2) If still using the spring suspension substitution of a heavier arm
assembly / mounting will cause levelling problems requiring you
to add (a lot of) mass around the turntable to rebalance it.
(Or add a "helper" spring, which I did in one of my mods.)

3) The spring suspension is compromised laterally, allowing
the demonstrations of the dynamically balanced arm having
no problems with the turntable being tilted at extreme angles.

4) You might have issues with the minimum LVX arm height.

rgds, sreten.

I like Dual 505's, but not my choice to try and make fly.
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When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 22nd April 2012 at 01:31 AM.
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Old 24th April 2012, 07:28 PM   #22
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I am picking the Linn Lvx arm up later this evening and have been exploring various ideas about armboard mounting.

What are the recognized principles of securing a VTA arm to a board and then the board to the suspension?

Does the armboard effect the arm's mass?

Should there be damping between the arm and board?

Should the board be sound isolated underneath?
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Old 29th April 2012, 12:22 AM   #23
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The platter will be cut to remove the right-hand section when viewed from the front. A Linn arm board will be fixed using an isolated cross bar and the suspension re-designed to cater for the increase in weight of the Linn arm.
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Old 29th April 2012, 01:16 AM   #24
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Click the image to open in full size.
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Old 30th April 2012, 01:31 PM   #25
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Some more examples of what is proposed:

Click the image to open in full size.


Click the image to open in full size.
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Old 1st May 2012, 07:30 PM   #26
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I came accross this thread by accident when I was preparing to post another topic. However, I was interested because I am also using a CS505 for a rebuild. The reason is that I want a semi auto unit but I cannot find anything else that would do the job apart from a CS5000 which has the added electronics complexity. I have also decided to add a second arm which is an Audio Technica AT1005 fitted with an AT120E cartridge. The dual headshell has been stripped of some mass by removing some extraneous bits and will now balance its VMS30E cartridge without any additional counterweights. The only other thing I have done is to remove all of the damping from within the suspension springs so it now bounces quite happily.
The Dual will be transplanted to a solid wood plinth sitting on Microsorber adjustable feet.
The AT arm will be mounted on the plinth to the left hand side of the Dual at the rear, facing accross the back of the dual unit. Obviously the AT arm cannot be used when the Dual unit is floating, so in this instance, the Dual will be clamped down to the plinth with three screws mounted where the current transit screws are. The AT arm height will be set up to this clamped down height.
There will be no dust cover as the unit will be quite wide and will be housed in a cabinet anyway.
Why am I doing all this? I want the semi auto function of the Dual but want to be able to use my beloved AT arm. I also want the removable headshell of the AT, the Dual headshell is now superglued together so is now fixed. The AT arm will feed into a separate pre amp and the Dual into the amps phono input
I'll post some pictures when complete.
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Old 1st May 2012, 08:13 PM   #27
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Sounds good Dave, the CS5000 is a good sounding turntable but is let down by the cheap plinth (chipboard).

Can't wait to see some pics.
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Old 1st May 2012, 08:40 PM   #28
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Yes, I was sorely tempted toward the 5000, especially when one came up for sale locally at a good price. However, I would have probably kept it standard and that wouldn't have been very DIY would it, and I like a challenge. I have always promised to find a TT that does the AT arm full justice, and one day I will find one. However, for now, this seems like a good way of using it without breaking the bank.
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Old 6th May 2012, 11:42 PM   #29
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Change of plan - the Dual 505 suspension and plinth will be discarded.

A Linn Sondek type suspension will be built along with a new plinth.

Click the image to open in full size.

I have three Linn springs but instead of the metal circus bearing I will use the existing Dual 505 bearing fitted into a wooden replica of the suspension plate.

Click the image to open in full size.

Click the image to open in full size.


The metal toplate from the Dual will still be used and cut, the pitch control and strobe platter will also be used but the arm board and arm will be Linn. Hopefully it will look like a Sondek with a smaller platter. The plinth is being built tomorrow.
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Old 7th May 2012, 09:52 PM   #30
sreten is offline sreten  United Kingdom
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Hi,

The springs appear to be upside down. I did spring layout by experiment.

rgds, sreten.
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Last edited by sreten; 7th May 2012 at 09:59 PM.
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