Shims for a taller cartridge seems wrong?

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doctor fuse
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Shims for a taller cartridge seems wrong?

Post by doctor fuse » 09 Jan 2019 07:52

I recently changed the Bias cart on my Planar 3 with RB300 arm, as I wasn't crazy about it.

I put on one of my favourite vintage cartridges, an Excel ES70EX4 with an aftermarket elliptical stylus (I broke the Shibata! :oops: ).

It is a couple of millimeters taller than the Bias, and sounds good on the arm. Except there seems to be more surface noise than this cart should transfer. I tried a thicker rubber mat and thinner felt mat but there wasn't any difference with the stock one, so it went back on. The vacuum-cleaned records play quietly on a Thorens 145 and a Technics SL-D2.

I have been reading that people recommend shims when swapping from stock Rega carts to different ones. I can't imagine there are that many there are the same height or shorter - only my Linn ASAK is shorter, of about a dozen I have.

Wouldn't a taller cart with shims make for an even more exaplggerated tail-down arm? I can't imagine how a shim would remedy VTA and stylus rake angle, unless it was a crazy short cart.

Please explain where I am making a mistake in my thinking, or if the recommendations for shims are totally off base ("but if I read It on the internet it must be true!").

DT999
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Re: Shims for a taller cartridge seems wrong?

Post by DT999 » 09 Jan 2019 10:17

When fitting a taller cartridge some fit an arm height adjustment spacer that fits between the plinth and tone arm which is what I think is what some refer to as a shim. This will raise the rear of the arm so the arm is reasonabley parallel when the higher cart is fitted.

Legrace
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Re: Shims for a taller cartridge seems wrong?

Post by Legrace » 09 Jan 2019 11:09

I have a 2mm VTA shim installed at the base of my arm to compensate for a taller non Rega cartridge. As noted in prior reply not to be confused with "headshell shims", these are normally for adding mass to an arm to better suit low compliance cartridges. Here your thinking is correct as a headshell shim is typically inserted between cartridge and headshell, thus adding height. So if you had a 2 mm taller cartridge and a 1 mm headshell shim it would be appropriate to use a 3 mm VTA shim.

On general subject of VTA shims these don't have to be an exact match. I target a tolerance of +/- 1 mm.

bbr620
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Re: Shims for a taller cartridge seems wrong?

Post by bbr620 » 10 Jan 2019 20:11

Rega Carts are 14mm in height, if the Excel ES70EX4 is 2mm higher then you need to Shim the armbase with a 2mm Shim to keep arm level. Below is a picture of a 2mm Shim installed at the armbase.

An easy way to check VTA is correct is with a piece of lined paper and looking at eye level ;)

Rega RB300 with 2mm Shim:

https://i.imgur.com/gjTFomB.jpg

VTA Check

https://i.imgur.com/O3T8daP.jpg

doctor fuse
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Re: Shims for a taller cartridge seems wrong?

Post by doctor fuse » 11 Jan 2019 02:06

Thanks for the tips, but.
Can't believe I've never thought of the lined paper check.
I have read stuff about the armbase shim needing to be about a mm higher than the additional cartridge height. So if my cart is 3mm taller than the Rega cart, I should use a 4mm shim. Because of the length of the arm and gravity and all that. Thoughts?

dysmike
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Re: Shims for a taller cartridge seems wrong?

Post by dysmike » 11 Jan 2019 03:33

I think if the arm is deflecting based on the weight of the cart, it's got bigger issues. So, nope I don't believe you have to shim more than the delta height.

dimucci
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Re: Shims for a taller cartridge seems wrong?

Post by dimucci » 11 Jan 2019 13:41

My RP10 arm (RB2000) is fitted with an Ortofon Quintet Black S, deeper than a Rega cartridge, and sounds superb.
Without any shims, the cartridge body is parallel with the record - although bear in mind that there will always be variances in the VTA when playing a180gm or "normal" weight vinyl.

Pikey
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Re: Shims for a taller cartridge seems wrong?

Post by Pikey » 11 Jan 2019 19:48

doctor fuse wrote:
11 Jan 2019 02:06
Can't believe I've never thought of the lined paper check.
There's a real handy Heybrook protractor that has lines printed on it ... look in the 'Tools' section for it!
38086

marimo
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Re: Shims for a taller cartridge seems wrong?

Post by marimo » 13 Jan 2019 07:30

Pikey wrote:
11 Jan 2019 19:48
doctor fuse wrote:
11 Jan 2019 02:06
Can't believe I've never thought of the lined paper check.
There's a real handy Heybrook protractor that has lines printed on it ... look in the 'Tools' section for it!
38086
What spacer did you use for your 2M Black? 2mm or 4mm?

Pikey
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Re: Shims for a taller cartridge seems wrong?

Post by Pikey » 13 Jan 2019 11:07

At the time I was using the Black it was 2mm , but I don't really enjoy the Black that much so I don't use it now.

I've tried several times but I find too bright and 'CD' like if that makes sense?
I know loads of other folks love the Black to bits but I just couldn't get it to sing properly , I'll try again another day I'm sure!

doctor fuse
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Re: Shims for a taller cartridge seems wrong?

Post by doctor fuse » 13 Jan 2019 16:27

Pikey wrote:
13 Jan 2019 11:07
At the time I was using the Black it was 2mm , but I don't really enjoy the Black that much so I don't use it now.

I've tried several times but I find too bright and 'CD' like if that makes sense?
I know loads of other folks love the Black to bits but I just couldn't get it to sing properly , I'll try again another day I'm sure!
The Black is rarely described as bright and cd-like (if you think a Grado sounds like that, NEVER try the AT95E!). I wonder if it is setup-related? Tail high? Not aligned adequately?

I upgraded the stylus in the Green, to an 8MZ, because it was so midrange and warm that I wanted a bit more resolution, and more controlled frequency extremes. I would still call it a slightly warm sound.

Pikey
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Re: Shims for a taller cartridge seems wrong?

Post by Pikey » 14 Jan 2019 20:15

doctor fuse wrote:
13 Jan 2019 16:27
The Black is rarely described as bright and cd-like (if you think a Grado sounds like that, NEVER try the AT95E!). I wonder if it is setup-related? Tail high? Not aligned adequately?
Well, partly motivated by your good self Doc I've just re-fitted the 2M Black to my RP6 and I'm going to give it another go! ... currently fitted with a 2mm shim , let's see if I can get this sorted out!

doctor fuse
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Re: Shims for a taller cartridge seems wrong?

Post by doctor fuse » 14 Jan 2019 22:55

Oops, you were talking about the 2M Black, which I don't know.
Cartridge swapping is fun, even on one piece arms.

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