Friday, July 6, 2018

The Perils of Using Tangential Arms -- Follow Up

The Perils of Using Tangential Arms -- Follow Up
The owner of the cartridge followed my advice and sent the cartridge to the manufacturer. It has just been returned and, upon inspection, I was shocked to realize how much of the original stylus shank had been worn out (Fig. 1) compared to the newly installed one (Fig. 2). For those "gurus" out there recommending air-bearing arm users tune the air pressure lower to get "fuller bodied" sound, please take a look at the two photos and reconsider your stance on the matter.


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Monday, July 2, 2018

Instrument-Based Method to Troubleshoot Hum

For years I've been advocating using instruments to aide troubleshooting hum issues, especially in vinyl playback systems. Due the diversity of component designs/implementations, the hum may be from the most unexpected causes/sources, and very often the resolution can only be found by trial-and-errors and step-by-step reductions before reaching the best outcome. Here's another recent example in my system.

After replacing the stock PSU for iPhono2 with a beefed up Acopian unit, I am quite happy with the sonic improvement, but when standing close to the speakers I can hear some humming, more prominent than my other phono stages such as the Avid Pulsare II. Even though no one can hear it at the listening position, I know the issue has to be addressed to reach optimal sonic performance, because the hum is just an indicator of how easily all kinds of unwanted noise can get into the system.

This morning I hooked up the measurement setup, and after trying out various grounding connections, I finally found the solution. Again, the best configuration is quite unexpected, and may not work at all in another system.



Turns out in the case, it's best NOT to ground the Acopian PSU and the iPhono2 chasis. Using the relative scale, one can easily see the reduction in each step.

Both grounded, the 60Hz component is set as 0dB: 

Disconnecting the ground wire on the Acopian PSU gets about -7dB:

Disconnecting the iPhono2 chassis ground gets roughly another -2dB: