Before I had the pre amp fitted I spoke to Martin and asked about the concentric control knob being a official “ Sadowsky” control knob and he reassured me it was , he fitted it very quickly which was great but meanwhile I had done the session in hand and didn’t really take much notice of the bass. He set it up great and was very pleasant to speak with . But on seeing other Sadowsky pre amp to fender conversions i then realised that something was wrong with my fit . I was supplied by Martin with the wrong Allen key also and had to order one from the net which was very cheap so that was no problem. I then unscrewed the two grub screws which are on the side of the concentric knob. I did this to see if I could lower it and not only could I not lower them the concentric is taller than than the others . This is not how a Sadowsky pre amp with TC is . Martin did explain before he fitted that he had one older pre amp in stock but would have to order or find a official concentric Sadowsky control. Once he had fitted and finished I had a brief conversation and again asked him “ you managed to get a Sadowsky concentric control etc and he said yes and that was that . I drove to the shop to pick my bass up and it was a rush as I had to leave as I only get limited time to come to London as I look after my wife who has chemo every two weeks and the visit to the gallery was a quick one ! Please don’t get me wrong they are all very pleasant and helpful, but in terms of fitting my bass with the Sadowsky pre amp was partly my fault for not checking and I’m possibly gone past being able to rectify it ? I’m going to check again and take photo and upload and you can tell me ? I could be wrong I’m not perfect 🙏🏽