Well known issue with VPI and Rega tables. A cap across the power switch of the right value is the answer. I had that issue years ago when I owned a Rega.
Turntables thump when turning off?
Why? I have used 4 different tables and three phono stages in 2 different systems and all of them produce a pretty loud thump when turning off especially, sometimes when turning on. I have been muting the system each time I turn off as it seems a little much to be letting such a thump reach the speakers. Is there a cure? lift grounds? arrange cables? I was getting a pretty decent hum at times and I've noticed careful routing of the cable to the phono preamp makes a huge difference in this.
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+1 @lewm This is a common problem- if the 0.01uf 1000v disk cap across the switch fails, it will result in a thump or pop no matter where that switch is in the system and it will show up more on the phono preamp. Its caused by the magnetic field of the motor or power transformer collapsing and causing an enormous high voltage spike (the same principle that energizes spark plugs in a car BTW). This is picked up by the phono section because it has the most gain. The cap shorts out the high frequencies that are otherwise jumping across the switch contact as its opened. For this reason it also prevents the switch from being damaged- the switch contacts erode a bit every time this happens. So you do want to get this fixed rather than use the mute! |
You know what the Doctor says to patient? It hurts when I do "x" Doctor-then don't do "x"
Yeah no sheet. I was looking for a solution to having to turn down the volume or mute each time I change the record. Just pointing out that if left at normal volume that I play a record at the thump is dang loud. Obviously I don't do that and I turn it down. Sounds like plenty of suggestions. I was thinking it's probably not a fault of one of the tables. I have a VPI classic 3, a Rega RP 8 that is brand new and an old Dunlop Systemdek IIX and they all do it and with two different phono preamps and various amps and preamps. I'll try some of the more careful wire routing see if that helps. Thanks for the many useful suggestions. |
Now that's an interesting bit of information! And that causes me to think its not a failed power switch bypass cap. You have something more basic. I would investigate your AC wiring- have an electrician test the outlet to see if its properly grounded and the AC wiring is correct. This could also be caused by an unshielded tonearm cable being routed very near the turntable power supply, but this latter idea is a bit sketchy. |
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