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Thomasvegeta 5th December 2011 04:38 PM

Pro-Ject RPM Tonearm replacement
I was wondering if we can replace the whole tonearm on a Pro-Ject turntable, especially for the RPM models and put an other one that has the same size (in my case it would be a Sonus Formula IV that I already owned 2 years ago).
Or do you recommend to build a base for that second tonearm?
It would be nice if someone has done something like this.

Best regards


Thomasvegeta 5th December 2011 08:27 PM

Well, I didn't check enough the species about the tonearm present on the RPM turntables. So my tonearm hasn't the same seize as the tonearms present on these turntables. But I'm still curious if we can replace the tonearms on the RPM turntables.

Bksabath 7th December 2011 06:54 PM

Sorry but why replace the tonearm? IT is the best bit of the RPM turn table.

I would keep the arm and trow the rest away.

I have not changed the arm on mine but did change the cables and got rid of the plugs on the turntable box.

Much beter now

I supose if you realy have to You could use a cartridge protractor
Mark the two point on the arck of the record and from there draw traingle with new arm lenght (stilus point to center of new arm turret) drill where the vertex lay.

Maybe just get a realy cheap and nasty piece of low density chip board and try that first.

Base of RPM is just that only I could not find a chip board that cheap and nasty any where.

So whith the normal staff you could get You may even end up with a beter turntable.

Just IMO the Sonus Formula IV is such a nice arm why waste it on the RPM?

Thomasvegeta 7th December 2011 07:34 PM

I mainly wanted to know if those turntables are easy to modify.
Thanks for the informations and advices.
Well, for the Sonus Formula, the thing is that I have no turntable anymore, I sold the one I used, so I need a new turntable. I don't want to spend too much money on it, and thourght a pro-ject entry level rpm would be enough for me.
I could perhaps make a new base, that fits for the Sonus Formula, and use the platter and motor of the rpm. Still have to think about it.
But thanks for the feedback :)

sakellogg 7th December 2011 08:00 PM

sure you can.
the new tone arm just has to have the same Pivot to spindle distance.
you might have to mod the arm board to mate with a different mounting setup.
if thats the case.........i would just make a new plinth out of wood (mdf) and make the arm part as long as you need for what ever flavor arm tickles you.
the Sonus Formula sounding better on this table, i don't know. i have never heard either.
if you have a line on a rpm with no Bksabath said make a base and measure out for your arm. if you have one with the arm...mesure Pivot to spindle and cross reference here
| Tonearm Mounting Distance and Alignment Information | Vinyl Engine
sounds like a fun experiment

Bksabath 7th December 2011 11:19 PM

Don't get me wrong I had the RPM 4 a few years and it works ok for the money

But that money was mostly on the Arm
The Sonus formula deserve much better

Ease to modify yess is just a piece of MDF all you need is to drill a hole on it
the link sakelogg postested is certanly a good one take your time mesuring up and then do it again

Plater and spindle of RPM yess ok with that altrought is Just a couple of pieces of plastic and another piece of MDF
Motor maybe not.., MC pick up pick up the mains nise going to it so maybe a decent DC motor is.

Yess sound like a good experiment but maybe you could get beter second hand base for the 300/400 of the RPM.

Seen a LP12 on Ebay auction for that money.

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