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First plug in the component's power cord and switch it on. If there are relays wait for them to switch. Now check the LCD display. The number indicates the voltage on the signal ground. This can be substantial. Remember the number and switch the equipment off. Wait a few seconds, turn the power cord's plug connected to the UPC by 180°. Switch the gear back on. Read the number on the display. The lower number indicates the correct plug orientation for this outlet. Switch off the gear and if necessary turn the plug back if the first reading was lower. Now unplug the power cable on the gear end. Take your voltage probe and find the ‘hot’ connection inside the IEC. As we look for correct polarity for this particular piece of equipment, we want to mark it for future use. Thus mark the IEC receptacle’s male pin that correspondents with the ‘hot’ female equivalent with something like a red sticker. This indicates now and next time where the ‘hot’ incoming line should be connected. When done the UPC can be removed and the next piece of equipment tested.

The above works for all outlets with protective earth. In case a PE-designated outlet is for some reason ungrounded (it suffers a slipped connection or was mislabeled as grounded), the UPC will indicate this by not lighting up a LED. It is not uncommon that a PE wire got loose or is plain absent. The UPC identifies this potentially dangerous situation. Next to such errors in home wiring, there are also simple two-prong wall outlets without PE and audio equipment with the (dreaded) figure-8 two-prong connectors. No worries, Ron Kemp provided his UPC with a grounding option. With the UPC comes a wire with a banana plug on one end and an RCA on the other. Plug the banana into the receptacle on top of the UPC and the RCA into any cinch connector of the equipment under test. In case of a wall outlet without PE the LEDs will not indicate where ‘hot’ is. Here you need your voltage probe again, then mark the proper position just like for a grounded outlet.

The above procedure is slightly different than what Kemp describes in the UPC manual where he recommends to mark ‘hot’ on the female IEC connector. That’s fine when everything is static and a specific power cord remains associated with the same piece of equipment. In the real audiophile world things are different. Equipment comes and goes. It is the particular amp, DAC or other kit which benefits from correct polarity. Hence our advice to mark the device, not cable. Probing an outlet with a screwdriver-type thingie is not everyone’s chocolate cookie. Many were zapped during childhood or later to still carry a minor trauma. For them there's hope. Use a non-contact probe like those by Fluke. Instead of sticking the probe into the connector or outlet, just hold the probe in close proximity. If there's life the tip still lights up. With the probed/identified hot pin and extra wire from the equipment to the UPC, measuring to find correct polarity is the same as for a grounded wall or equipment outlet.

Because everything electrical connects with each other through the house wiring, we thought it made sense to not only check and correct all our audio gear but also all other electrical equipment. So we made a tour through our digs armed with the UPC to get as many devices as possible oriented correctly. This included the central heating, the fridges and freezer, a TV and Marja's sewing machines. Of these the PE-equipped ones were easiest to check and correct. Others took more effort to find something that would accept the auxiliary cable. How much benefit we gained from this exercise is hard to quantify. Yet there was one definitely rewarding item. The fridge in the kitchen. It now runs even quieter after we reversed its plug. Good dog. The UPC is primarily designed for audio. This assumes the use of straight power-cord plugs. Many household appliances however use 90°plugs to allow the cable to run flat. Using such plugs with the UPC obscures its LCD display. In conclusion we think the Kemp Elektroniks Ultimate Polarity Checker should be standard issue in every serious audiophile's tool box. Additionally the UPC should be in the tool belt of every self-respecting audio dealer and become part of his mandatory house call service for all customers, be they audiophiles or 'normies'.

Condition of component received: The first UPC had a faulty LED but was replaced immediately.
Reusability of packing: Many times.
Website comments: Lots of information and well maintained in English, Dutch and German.
Completeness of delivery: Included user guide.
Pricing: Fair.
Human interactions: Responsive and friendly.
Remarks: To make the UPC set as delivered complete we would like to see a set of marking stickers and an optional non-contact voltage probe like the Fluke. Another suggestion is the relocation of the LCD display to allow easy reading when using 90° power plugs. As the UPC is Schuko only, Kemp might come up with an adaptor or solution for non-Schuko markets. [This would include Argentina, Australia, Brazil, China, Denmark, India, Israel, Japan, New Zealand, South Africa and Switzerland as countries with various asymmetrical 3-prong sockets and plugs which don't allow for easy rotation like Schukos – Ed.]

After we'd penned the above, Ron Kemp commented that he has toyed with the idea to develop adapters for the American and other non-Schuko markets so that phase and neutral might be reversed. When he discussed this with his distributors in the US and Britain, their technicians thought the idea ridiculous. That's because they are unfamiliar with the power phase issue and its obvious impact on the sound. That's at least his experience. Ours is different. We even know Americans who converted part of their A/V power distribution to Schuko to to get this phasing correct. Another remark by Ron is that gear with embedded powerline filters or switch-mode power supplies has no polarity preference due to the use of Y capacitors which sit between hot and ground and between neutral and ground. Here our experience with SMPS-powered gear like the Devialet D-Premier and Hypex Ncore 1200-based power amps is different again. Using the power plug orientation which corresponds to the lowest UPC reading definitely has an audible and positive influence on the sound quality.

Kemp Elektroniks website