Quote Originally Posted by YNWaN View Post
Hi Panos, to be honest there are a whole bunch of potential issues.

With regard to the thump there's nothing you can do and nor is there any need to. If you were to tap the sub-chassis of any turntable during play you will hear some thump through the speakers (unless perhaps if it is extremely heavy and dense but that brings other issues). The chassis is supposed to be isolated from the outer plinth and the rest of the world, as such your tapping of the top plate is not an input it should see (unless you bypass the suspension by deliberately tapping on it ).

The motor issue is another matter. I'm afraid I'm not overly impressed with the OL speed controller and a friend who had one found its speed stability to be deeply questionable. Attaching it to the top plinth also means that all vibration is effectively coupled directly to the platter and arm. I realise you have added some rubber shims but that is unlikely to be having a significant effect I'm afraid. In addition, one of the primary design features of the Xerxes was the rotating motor and this has obviously been lost in your modification. Further, in general, I'm not convinced by the use of DC motors in turntables and after years of experimentation have settled on AC (but that's another long winded story).

The problem with adding compliance to the arm base is that if it is sufficiently compliant to reduce the transmission of vibration it will be decoupling the arm. The point of the chassis is to act as a drain for vibration emanating from the arm (from the cartridge originally) and adding a rubber washer will work against this. The rubber is also likely to create an uneven level of damping which is also undesirable.

Sorry, it's all a bit negative - if you like it that's cool and all that matters. Unfortunately the Xerxes power supplies have gained rather a reputation for being a bit flaky in the long term so I quite understand why you abandoned it.
Matt, the point IMHO is not to be positive or negative. I do not mind that at all. It's about sharing experiences and helping each other to do better. So, I really appreciate your sincere feedback, as it highlights points you think could be improved on my deck. Quite right so.

I had at least two failures of the original Roksan Xerxes PSU and the repairs seemed to me rather costly at that time. That's why I decided to go for something else and I stumbled upon the OL DC motor. It was before 2000 when I replaced the motor, if I remember correctly. It seemed like a big improvement to me then. From a reliability point of view I had no issue at all. Recently I upgraded the controller unit with a new 'advanced' controller from OL again. It we me to be able to maintain a very constant speed. But I have used it only for a few tens of hours until now.

I have read also various opinions in favor of both DC and AC motors. I have no personal experience or knowledge on the issue, but the AC case locking on the power network's frequency (50 or 60 Hz) in order to keep rotational speed constant, seems pretty reasonable.

I wonder whether I could try alternative motor solutions on my Xerxes to see if they work better than the OL motor. Perhaps the recent ones from Roksan could be retrofitted to my Xerxes? In any case I am not eager to pay an arm and a leg just out of curiosity.in any case, Roksan's idea of the rotating motor seems rather strange to me. I would expect than at any point the stylus friction increases, the motor will just turn, instead of trying to overcome that friction and keep the speed constant. Am I getting something wrong here?

I will continue experimenting. The method is quite clear. Trial and error... -))