Turntable power supplies for decks with AC motors
AC motors spin at the speed set by the frequency of the mains supply they are connected to, in the UK this is 50Hz (I.e. 50 cycles of a sine wave form per second).
Which decks respond to power supplies?
Basically if your turntable doesn’t already have an electronic power supply (either internally or externally) and uses an AC motor then it should really benefit.
In terms of matching a power supply to your deck all you really have to be aware of is its power consumption, which is generally listed on the back of the deck or in the manual. However as a generalisation most decks on the market (Linn LP12, Rega, Systemdek and so on) use basically the same type of motor and will work with any of the universal power supplies.
Why do they work?
The circuit inside most turntables is in essence a very basic Resistor/Capacitor network. The capacitor is in place to make sure that the platter always spins in the right direction when you turn it on. This is a very cheap and simple way of making a turntable, and in a perfect world would be a perfectly satisfactory. However this not being the case the motor ends up directly seeing all the impurities and irregularities that are a feature of the mains supply.
For example whilst in the UK the mains is supposedly 50Hz it actually varies*, this can results both in absolute pitch change and stability problems. So the ability to generate a new mains waveform can be very beneficial, not only do we guarantee that the speed remains stable but it should also be possible to make it much cleaner with less noise and distortion than exists on the mains.
*in fact all the electricity board have to do is maintain an average of 50Hz with a 1% tolerance throughout the course of 24 hours, to ensure that AC powered clocks keep good time over the course of a day.
Why are some power supplies more expensive than others?
Despite the apparently simple brief of producing a power supply that outputs a simple sine wave there’s a lot more to it than that. The quality of the waveform produced (in terms of its distortion), its tolerance of frequency variation and background noise are all elements that go towards explaining why some are more expensive and (all things being equal) better sounding.
Project Speedbox MkII £105
Specifically intended for use with Projects own turntables, this box outputs a high quality wave form for the 16V motors used on their decks. It also provides the convenience of electronic speed change.
The Rega TT PSU is designed for use with all the latest 24 volt motor Rega turntables,
including the P3 24v as well as the P5 and P7 (and all older Rega turntables that
have been retro fitted with their 24volt motor upgrade kit). The TT-
The latest version picture here features improved power supply regulation, output circuit protection and a new anti vibration circuit. It is available in both black (pictured above) and silver caswork.
Rega TT-
The Edwards Audio Iso1 uses a high quality mains isolation transformer, an approach
we’ve been championing for many years due to the excellent results they achieve.
This can be used with any turntable, from Regas through to Garrards and can also
be beneficial when used before other turntable power supplies (as well as CD players,
pre amps -
The resulting improvement in sound is greater timing and dynamics, with blacker backgrounds and a generally cleaned up sound, and due to its near universal nature it can stay with the system as you upgrade, making it a very cost effective upgrade.
Edwards Audio Iso-
The Project Speed Box SE is the most affordable universal turntable power supply we’ve come across, its has two output on the back, one 16vAC feed for Project turntables and also a conventional 13A mains socket rated at 3 watts (although this figure seems a little conservative).
We found it works brilliantly with many turntables including the Rega Planar 2, 3 & 25, Roksan Radius 5, Nottingham Analogue models, Wilson Benesch Circle, Systemdek IIX, Clearaudio Emotion & Champion, the Manticore Mantra and many others.
The Speed Box SE not only produces a good quality signal with the sonic improvements you’d expect, it also provides fine speed adjustment in 0.1rpm increments and the convenience of a 33/45 speed change switch, as well as a standby mode to stop the platter spinning.
Project Speed Box SE II power supply: £410
Martin Bastin Wave Mechanic: £500
The Wave mechanic is a mains regenerator much like the Project above, but as its price suggests its made to a much higher standard. It outputs a single frequency so you don’t get the convenience of speed change buttons (you have to move the belt on its pulley as before), but it does allow very fine tuning of the speed via the front mounted rotary control. It is supplied with a female IEC connector to fit to your turntables power cable as well as a strobe disc to ensure that the speed is set accurately.
The standard version has a power output in the region of 7-
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Above: rear of Wave Mechanic
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