Foam Filling an Arm

[johncaul]

Hi all, has anyone got any experience foam filling their tonearm? It's something i'm toying with. I'd be interetsed in hearing about what foams people have used, installation and impact on the sound quality. I'd also be interested to hear if anyone's used the audio origami service for 15 pounds, given how good value it looks i might also be tempted to outsource! I've got a rega 251.

Cheers all
John

[hifi_dave]

IMO, not always an improvement. Try wrapping insulation tape tightly around the arm tube and see what that does before or instead of getting it filled.

[DSJR]

Firstly, a Rega RB series arm has but ONE main resonance, very very high in the upper midrange, which no amount of foam will alter IMO. According to HFW, the RB300 series has a secondary resonance which is apparently the tracking-force spring. Unlike other tonearms, which can ring like bells over a wide range of frequencies, the "best" way to "sort" the Rega pipe is possibly the Avondale way - a long threaded bolt which clamps the beam at each end, tightly coupling the ends together. I'm not sure whether this ever became a commercial entity though.

Seriously, accept the RB251 as the bargain it really is and of you must look at a modified one, get a good used Michell Technoarm, which at least is properly and professionally done. An Incognito re-wire done by Moth Marketing (Moth's Mike Harris has the proper jigs and the Rega training to do it correctly) will really be all you need - trust me.

[YNWaN]

I have considered this issue a great deal as producing a tonearm is one of my interests. Superficially the idea of running a tensioned wire within the armtube seems like a good one; but, on further reflection, I am less convinced by its efficacy and can see a number of issues relating to both it's conceptual benefit and/or implementation. At worst, it provides little more than a secondary, parasitic, resonating element.

I is also worth noting that one of the more popular Rega mods is to remove all of the paint from the armtube. This mod will definitely make the arm more lively and reduce damping. It must therefore raise the question whether damping is actually beneficial.

[hifi_dave]

Exactly, hence my comments above. Sometimes damping is a good thing, sometimes it removes the life and excitement from the item, though that might just be resonances.

[YNWaN]

Yes indeed Dave.

This article may be of interest to some (although it considers laminated structures and therefore partly details the effects of shear).

http://eprint.iitd.ac.in:8080/bitstream/2074/2378/1/singhfre94.pdf