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Directions in SPUs - Tonearms, advice sought, reflections on gear...

Discussion in 'classic' started by naimnut, Dec 22, 2021.

  1. G T Audio

    G T Audio Trade: Manufacturer and Distributor

    There is nothing to stop you using an SPU with a modern conventional tonearm. Just go for one of the nude versions (SPU Classic N or SPU Royal N). These are 13 grams. We used one of these at the 2012 Munich show in a €1M system and it sounded superb.
  2. montesquieu

    montesquieu pfm Member

    Thanks Scott.

    Really interesting on the 51mm drawing, I've mainly focused on modern SPUs which are pretty consistently 52mm, but I've had a few vintage ones measure 51mm (and also one SPU #1S), I always put the shorter cantilever down to variable quality control but it seems it was likely intentional at least with the vintage ones.

    Not having any SPUs any more I now set my Japanese arms up at 50mm ... I used to use the handy Technics alignment tool which was set for 52mm (interesting actually .. I guess that means Technics geometry is set up for SPU!) but when I moved to 50mm, I made a 2mm shortened version of the tool, and also melted some additional slots to accommodate headshells with pins or guides on both sides .. incredibly useful things for removable headshell tonearms.


    Funnily enough that's what's inside the 'Swing' headshell in my pic above with the RMG309i .. an SPU Royal N. Tonearm mass issues still apply though, it's just as low compliance as the other SPUs, even if coming without the additional 16g of headshell attached.
  3. Shuggie

    Shuggie Trade: Ammonite Audio

    Effective mass is all about inertia at the stylus point, so I tend to agree with you here. Any G or A shell SPU is so heavy that the arm's actual mass is not so important, assuming it can cope with the weight of an SPU and balance it out. What is important with SPUs is how the arm deals with the rather high levels of energy that these cartridges push back into the arm's structure, so arm designs like Glanz that take resonance control seriously will tend to yield much better results with even the cheapest SPUs. Note that I am talking here about resonance control, and not damping! Here, the best arms that I've heard to partner SPUs are Groovemasters and Glanz, both high mass designs.

    As Tom has said, it's very easy to get disappointing results with SPUs, certainly compared with most modern MC cartridges, but pair them with a good arm and a well-matched step-up, then a certain musical magic happens. Yes, they are in many ways quite flawed, but forgiveably so given the vibrant, colourful and dynamic sound character that is a joy to hear. But, not all the time! Like Tom, I listen with SPUs when the mood takes me, which to be fair is quite often.
    Nagraboy likes this.
  4. G T Audio

    G T Audio Trade: Manufacturer and Distributor

    I wouldn't touch anything made by Project, having been involved with them indirectly when they first started out. I remember supplying an amplifier/speaker system to a client in 2008 who couldn't afford a Platine Verdier at the time, so he bought a new Project turntable and tonearm. It was fitted by a dealer in the west midlands. The client wasn't impressed when I pointed out the carbon fibre headshell was about 3 degrees off from central. It was replaced very quickly after that. Even when the tonearm was replaced with a "straight" one it still didn't sound that good.
  5. G T Audio

    G T Audio Trade: Manufacturer and Distributor

    Note: Modern SPUs weigh between 28 grams and 35 grams depending on model and require between 3 grams and 5 grams of tracking force. Older models may well be heavier. Some of the Classic GMs I supplied in the 1990s and early 2000's were 32 grams. The 1950/60's SPUs will have the internally mounted piggy back MC transformers fitted, so will be heavier still.

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