What RB250/RB300 counterweight mod? - diyAudio
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Old 9th November 2008, 02:33 PM   #1
Shaun is offline Shaun  South Africa
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Default What RB250/RB300 counterweight mod?

I am trying to help a friend decide which offering to go for regarding the modification of a Rega RB300 tonearm counterweight.

Options we are aware of are:

Michel TechnoWeight
Origin Live Structural Upgrade
Audio Origami Counterweight
Expressimo Heavy Weight
Audio Mods Counterweight

I'm looking for opinions from anyone who may have had the opportunity to compare these options, as well as recommendations.

The budget is tight, so he is looking for the most cost-effective option.

Thanks!
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Old 9th November 2008, 04:42 PM   #2
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Make your own?

I've seen & heard a diy one made from Teflon & brass that is very good.

dave
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Old 9th November 2008, 04:47 PM   #3
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Hi Shaun


Has the Rega been rewired? IME it's the only cost effective upgrade. All these fancy counterweights certainly change the sound but not necessarily for the better. Either diy or buy a better arm.
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Old 9th November 2008, 08:52 PM   #4
Shaun is offline Shaun  South Africa
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Quote:
Originally posted by planet10
Make your own?

I've seen & heard a diy one made from Teflon & brass that is very good.

dave

Quote:
Originally posted by analog_sa

Has the Rega been rewired? IME it's the only cost effective upgrade. All these fancy counterweights certainly change the sound but not necessarily for the better. Either diy or buy a better arm.
I believe that DIY is certainly in the realm of possibility, including rewiring. I can't make the mechanical parts myself, but I can find someone who can.

So, some questions need to be answered:

(1) What is rewiring meant to achieve (apart from the cheap phono plugs and earthing via the signal ground)?
(2) What is the principle of operation of the counterweight mod? Is it simply about tighter coupling to the stub? Can I, for instance, just add a grub screw to the counterweight? ...claims of lower centre of gravity improving matters?

"Buying a better arm" does not fall within the scope/budget of this effort.
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Old 9th November 2008, 09:33 PM   #5
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Hopefully Tubenut reads this as he would be much better prepared to recommend rewiring options. What i like about the rewiring is that the materials cost very little and the entire exercise is easy and fully reversible. At the time i listened to two sets of wires cellotaped to the Rega tube which made it easier to compare to the original wiring. Ended up with a single 1m length of screened Cardas awg33 with the screen removed inside the arm. Also used Cardas cart clips which made a surprisingly big difference.

When Origin Live started the entire business of counterweights for the Rega they specifically warned against keeping the original stub and adding a grub screw. Maybe it was just marketing. A lower centre of gravity seems beneficial.
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Old 9th November 2008, 09:55 PM   #6
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Quote:
Originally posted by analog_sa
A lower centre of gravity seems beneficial.
Why? This arm do not have a unipivot (single point bearing).

Roger
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Old 10th November 2008, 03:32 AM   #7
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Quote:
Originally posted by Shaun

(2) What is the principle of operation of the counterweight mod? Is it simply about tighter coupling to the stub? Can I, for instance, just add a grub screw to the counterweight? ...claims of lower centre of gravity improving matters?
The idea with this one is to have less coupling.

dave
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Old 10th November 2008, 04:48 AM   #8
Nanook is offline Nanook  Canada
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Default p10...

well yes and no...

the brass "slugs" lower the CofG substantially. So there are two benefits to that particular counter-weight: decoupling and lower CofG.

by lowering the CofG of the counter-weight, the likelihood of setting the cartridge end in motion due to a large vertical movement (such as a warp on a record) is greatly reduced, as it will require a larger force to overcome the Inertia of the counterweight.

If the CofG of the counterweight is higher than the plane of the record, a smaller force acting on the cartridge (and thus "pushing up against it), can create a larger change in the force acting on the counterweight, thus upsetting it.

draw ye some vector diagrams (remember those , my friends?), and you can easily convince yourself.

stew
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Old 10th November 2008, 06:52 AM   #9
atavid is offline atavid  Australia
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For what its worth, i've changed to the Michell Technoweight and i noticed an immediate increase in the weight of the bass and a little less coloration in the mid areas.The change is not subtle, so you will be in no doubt as to its effect on your system.How it will sound with your combination of components is anyones guess.I suppose we all take a chance when we modify our gear.
Like all of us I would hate to think i spent $200 on a mod that didnt improve my system, but i am not one to try and fool myself just because i did spend the money,however i can say that in my system, i like the changes the Technoweight made to the music i listen to.
Ive also just purchased a Pete Riggle VTAF but havn't had a chance to listen to it yet as i am in the process of doing some more major modifications to my turntable.
The last mod i will be doing is the Incognito rewire in a few weeks time after i've had a chance to listen to the effect of all the other mods.
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Old 10th November 2008, 01:53 PM   #10
AMV8 is offline AMV8  United Kingdom
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shaun

If it is the RB300 that is being modded I think the best mod is to remove any influence of the weight setting spring. ( This does not apply to the RB250 which does not have the weight setting spring fitted.) I find that the playing weight is best set by moving the counter weight along the arm.

The next best mod I think is to substantially increase the weight of the counterweight so that the tracking force can be set with the counterweight closer to the pivot. I added a lead ring around my counterweight.

I also dispensed with the set screw idea and tightened the counterweight by added a few wraps of plumbers PTFE tape in the threads.

(I have never tried changing the stub so I do not know what difference that makes.)

These mods made a big difference and made the mid and top cleaner when I upgraded my RB300 and RB250.

I think better wire also helps and I use silver wire.

At the end of the day the final result you will get is really set by the quality of the bearing in your particular arm. Thr Regas seem to be to a very high quality for the price. You have to pay much more to gat a much better bearing. But, you do get some variation in the Rega bearings and that is probably what will limit your particular arm.

Don
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