Armboards

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Notraddad
Scotland
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Joined: 03 Sep 2019 23:05

Armboards

Post by Notraddad » 09 Nov 2019 20:11

I have a heavy armboard with 3 holes. When I try to mount an RB 300 arm it leans too far over so the platter is only about 2mm from the top plate on the right side. I have considered reducing the circular piece underneath that is weighted. Does anyone know if it is full of lead shot that would roll out if I were to drill into it? It also seems impossible to get the substantial arm cable to go through the appropriate slot. In particular as the cable exits below the honeycomb chassis. Also, the hole in the board is offset to one corner...Is that to accommodate a 12" arm?

wine man
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Re: Armboards

Post by wine man » 11 Nov 2019 19:02

A Rega arm requires just one hole in the board for the central pillar & cable. Each PT board is machined and weighted specifically for both the fixing and geometry of each arm. It sounds as if you are trying to mount the RB300 into a non - Rega board (it definitely shouldn't have 3 holes). Where did the armboard come from?

Cloudbase
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Re: Armboards

Post by Cloudbase » 11 Nov 2019 20:22

I think the Rega 3 point thingy is used as a spacer so it can be used on the TT but usually just bolt the arm direct to the armboard.

If your TT is an Anniversary where the platter floats on the same springs as the armboard then adjust the "sleds" to balance the weight of the arm/platter including the cartridge as well.
I havnt owned anything other than a LPT (no springs) or an Anniversary so cant comment on other models but arnt the platters unsprung on those turntables?

As for the weights on the armboard, they can be removed. More info on what equipment you have would help.

Notraddad
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Re: Armboards

Post by Notraddad » 11 Nov 2019 22:47

It appears to be a PT Too from the descriptions on this site. With sprung chassis and black power supply. They collar with the 3 holes that match up with the ones in the armboard for the fixing screws is a spacer and it was too high. I think I may try fixing it just using three large washers I bored out to fit the arm & I'll probably just run the cables out of the hole in the base.

wine man
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Re: Armboards

Post by wine man » 11 Nov 2019 23:17

The rear of the armboard (where it fits to the sub chassis) should have a small rectangular cut out for cable exit - I owned a PT2 and had both Rega and SME boards, both had this feature. If you are struggling I would strongly suggest getting a knowledgeable dealer to sort this for you, PT decks need correct set up to give of their best.

Notraddad
Scotland
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Joined: 03 Sep 2019 23:05

Re: Armboards

Post by Notraddad » 12 Nov 2019 01:17

There is small slot wineman. However, as each cable is about 1/4" thick and the bottom of the threaded arm base protrudes about an inch, the cable would need to be bent up quite severely and would restrict any free movement in the suspension. I may look at replacing the heavy cable with some very thin silver wire that I have. I'll sort it myself.

tim_bissell
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Re: Armboards

Post by tim_bissell » 15 Feb 2020 23:06

Suspended turntables and stiff thick tonearm cables don't work well together; Rega seem to be particular offenders, probably as they make only fixed turntables.generally for PTs you bend the tonearm cable up through 180 degrees towards the front (not too sharply; have some sympathy!) then forward 90 degrees so it lies on the subchassis. Loop gently round through 180 degrees and exit through the cutout at the back of the plinth.

These days most phono plugs are too thick to fit through the gap, so check first. My alternative approach is to do the 180 degree the forward bit, but loop the leads in a spiral under the subchassis and out of the hole under the tonearm pillar.

tim_bissell
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Re: Armboards

Post by tim_bissell » 15 Feb 2020 23:11

One question not asked was whether you have tried adjusting the suspension? Do you have the thin-wall socket spanner needed?

The arm + cart + armboard + weight should come to about 800g altogether, if they are to evenly counterbalance the platter, and provide a nice bounce on the springs.

in general Regas need about 350g of ballast; PT glued 350g lead cylinders onto their armboards.

cgm18
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Re: Armboards

Post by cgm18 » 19 Feb 2020 23:14

hello there, as an alternative I don't have my PT set up at the moment, i purchased it 2nd hand several years ago, when it came the baseboard was just cheap thin plywood (tacky), i removed it & sat the plinth / turntable on sorbothane isolation feet at each corner. This allowed the tonearm cable to drop straight down & exit without affecting the suspension / subchassis.

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