MM cartridges

Dover and Dougdeacon, what is it about the Audiomods arm that makes it unsuitable for use with Decca/London cartridges? The common wisdom has always been that they like damped unipivots, but London importer Warren Gregoire tells me they actually require a stiff arm tube and good bearings, both of which the Audiomods arm possesses. As to effective mass, the compliance of the cartridges is 10X10-6cm/dyne vertical and 15X10-6cm/dyne lateral, which requires an arm of medium mass to get the arm/cartridge resonance around 10Hz. The Audiomods can be had with a counterweight of several different masses, one of which will enable that figure to be reached. Are there other considerations than those I've mentioned?

Bdp24,
I would agree with the Decca importer - stiff arm tube and good bearings. I have set up about 20 Deccas in various arms.The most common back in the day here was the Linn Ittok. Results were variable.The best results I got from a Decca were with a Zeta tonearm, stiff arm tube and good bearings. I had an Audiomods arm on my Verdier briefly - it is excellent value for money - but I would not put a lower compliance cartridge in it. It is a bit like putting formula 1 or Indycar tyres on a Toyota Prius. Yes the tyres are better but the handling will be worse. At worst I have seen damaged records from mistracking Decca's ( remember there is no cantilever ) where the arm has not been good enough.
Arm cartridge matching is a bit of a lost art today, because with internet purchasing dealers cannot afford to carry a variety of arms & cartridges. Specifications do not always tell the story. Because nothings perfect even the best arms and cartridges are a panoply of resonances - thus results vary considerably with different combinations. The Decca is at the low end of the compliance and due to the lack of a conventional cantilever does impart a lot of energy that has to be managed by the arm. I would only recommend it with a top arm.
Probably the best analogy I can give you is the Rega RB300 back in the 80's when it was launched. A lot of folk on a budget put Koetsu Black cartridges on the Rega RB300 because the arm was "good enough", that is, it did not mistrack and they like the Koetsu sound. However it was easy to demonstrate that if you replaced that with a much better arm ( e.g. Zeta/Alphason/SME ) and a good quality medium compliance MM ( e.g. Grace F9E ) then the overall result was more relaxed, more musically coherent and ultimately more enjoyable.
Another example of the TT/Arm/Cartridge hierarchy - I initially set up the Verdier with the Audiomods and a Goldring MM. In the same system I had running an SME20/SME V/Lyra Skala SL. The Verdier combo absolutely left the SME combo for dead despite the disparity in cartridges.

Great Dover, thanks for all the info. The Kuzma Stogi Reference looks like it might be able to handle all the physical energy the Londons (or other low-compliance designs) throw into an arm. The arm tube is pretty massive (similar in shape to the SME V), and Frank's bearings appear to be respectable, though they are only common carbon steel of a good but not excellent grade. Have you mounted a Decca/London on a Reference?

Oops, sorry for hijacking the thread. I shan't do it again mates!

I running the Decca Jubilee on a Graham 2.2 (unipivot), and have consistent excellent results. I would consider it in my top 5 (out of 70+) cartridges. I also used it on my JVC 7045 'S' shaped arm with the same excellent results.
Of course you want a arm with good bearings! Why would anyone want a are with 'bad' bearings?