Ingvar Ahlberg
Well-known member
No Johan, the SP3 did not have a switchable high pass filter, nor does my present SP6, on the other hand they have input and output capacitors so have a fixed filter but at a far lower frequency.I think even the Audio Research SP3 had one. Ingvar?
The GAS Thaedra has one, switchable from not engaged to 10, 20, 30 and 50Hz, this is before the volume control in the circuit so does not help when the output stage DC servo stops working so it can then produce some heavy DC output, but no rumble pass through.
A very long time ago, very long, when the first Rega Planar and Planet were introduced in Sweden and we discovered how feedback prone they were a friend got a good idea, a very good idea.
So we cut a piece of 18mm plywood the same size as the the Rega chassis and attached an 16" bicycle inner tube to that in a way gave it a "more or less" rectangular shape and inflated that, the Rega put on top of that, floating on the inflated inner tube, was totaly imune to feedback, that idea was later found in comercial gadgets, pretty expensive but still using a bicycle inner tube inflated between two layers of wood or plastic boards.
The tennis ball approach is good but only Dunlop Wimbledon grade balls work, no cheap Adidas balls.
Ingvar