Mounting the cartridge

hifi-TP60The needle should be at the correct distance from the tonearm’s bearing. Thorens provided a headshell gauge as a guide for mounting the cartridge on the stock TP-60 mounting shell. Both the TP-16 and the TP-11 tonearms mounted on the TD-160 (the one I currently have) and the TD-165 (the one I owned before) turntables, respectively, have a TP-60 shell. I don’t have such a headshell gauge, so I calculated the key distances from the scale drawing on the TD-165 manual: from my calculations, the needle has to be at about 24-25 mm in vertical from the headshell’s outer edge and 7-8 mm (better lower it down to 4-5 mm – as better explained in the cartridge alignment page) horizontally from it (click on the picture at right for an enlarged drawing). With additional patience, it is quite easy take those measurements while the headshell has been removed and placed upside-down on a table. It is as simple as aligning the cartridge by sliding it back and forth until we measure the correct needle position.

The problem with certain cartridges like my Grado Prestige Gold, is that they are not “tall” enough and their needle will always be at less than 24 mm form the headshell’s “roof”. Shims must be used, spacers that were purposely provided by Thorens along with the headshell. Some are sold on the market but I couldn’t find any. So I solved the problem with a DIY solution: plastic badges holding cellular phone SIM cards are usually thrown away besides the fact they have vital PIN and PUK codes written on them; I found out their thickness is just half the one I needed to correctly position my cartridge’s needle. I cut two rectangular pieces and I placed them between the Grado cart and the Thorens headshell: the needle fell at 24 mm as required. Some Lego small bricks, those with a smooth face, possibly black, can also be used, being 3 mm thick. Even better, I’ve recently obtained them from thin PCV sheets. I real pain in the back are the cartridge mounting screws, which aren’t usually long enough to secure the cartridge after the spacers have been installed. I had to find and buy the proper Thorens-compatible, non-magnetic screws and washers.

At this point, a protractor shouldn’t be necessary, but it is still advisable to use one for a final check. It is very important the needle is at the correct position along the tonearm. There are several different thoeries about the correct alignment of a cartridge along a tonearm (see the alignment page).

headshell_leadsA very useful upgrade everybody should do on all old Thorens headshells is replacing the 4 leads that connect the cartridge to the tonearm. The original ones are very thin and the contacts are dirty and rusty. As a first step, it is a good idea to remove them and polish all contacts – even the old leads’ – with de-oxi fluid and a small brush. headshell leadsBut they should be replaced as soon as possible. Several types of substitute leads are available on the market. They are compatible with almost every headshell around. Some cost a fortune, but I managed to find good, gold plated terminals for just a few euros. I didn’t expect such a good result: it was as if the classical “veil” had been removed from the music. The leads are thicker than the originals, so they weigh more (0.18 g each); this affects the tonearm/cartridge assembly’s resonance frequency, since I have a heavy arm and a rather compliant stylus. In order to lighten the arm a bit, I removed the Thorens logo plate and a small piece of plastic form within the headshell.

Hi-Fi-News-Test-Record-imageAccording to the usual mathematical formula, I didn’t obtain an optimal relationship, but I didn’t notice tracking problems or background noises. Then I purchased the very useful HiFi News Test Record.

It contains several tracks with different signals useful to verify the correct tonearm/cartridge interaction. A really useful track is that for verifying the resonance frequency of the arm/cart system. What really surprised me was that the frequency I obtain mathematically for my TP-16 tonearm and Grado Prestige Gold cartridge is around 7.5 Hz. The optimal range according to HiFi News is 8-15 Hz. The Test Record’s track gives a resonance frequency of around 13 Hz, far better than mathematical forecasts.

Another interesting track is the one considered to be a torture even for high-rated systems. To my great surprise, after having optimized the alignment thanks to the test record itself, my Grado Prestige Gold with 8MZ stylus passed even the terrible test: it stayed in the grooves. It seems that even the acclaimed tracker Shure V15 VxMR TNT-Audio’s Geoff Husband loves so much had been “spat off the record” on his very expensive SME IV tonearm. Not bad!