How does turntable PSU work?

Sunsun22 · 28th February 2005, 03:10 AM

I recently bought a Project RPM 9 turntable. The salesman told me that the Project Speed Box is a MUST option. Other than it can change the speed of the turntable by simply pushing a button, it smoothen the motor rotation by recreating a perfect sine wave from city current and the result can produce a better sound. He lent me the speed box for one week so that I can try it out at home.

This speed box is a very small box that cost me only US$59. I tried my turntable with and without the speed box and the different is audible. The violin is silky smooth and it becomes very noticeable when I played the Eagle¡¦s Hotel California. The bongo¡¦s echo is clearly reproduced.

There is a more expensive Project Speed Box SE that cost US$370. The box is much bigger with display showing the rotation speed, calibration of speed in steps of 0.1 RPM and a 220V AC 3W outlet at the back. As explained by the salesman, this is a better option because the speed is more accurate, the sine-wave is more perfect and the AC outlet can control other turntable's AC motor provided it consumes less than 3W. However, the salesman is not able to lend me the SE for trial at home.

Since the small Speed Box is already good, does it really worth to go for the SE considering such a big difference in price? Actually, I also wish to know how does the turntable's PSU works? Is 3W able to drive most turntables' AC motors?

Thanks you

Netlist · 28th February 2005, 11:54 AM

To me this speedbox is nothing more then a regulated power supply with variable speed settings. The SE version has the advantage of a display for the readout of the speed. From what I found, the speed can be set more accurate with the SE version.
The speed box ‘light’ will (read: should) be as accurate as the SE if its well build, only the SE gives you a better and visualized control.
Personally, I think the price of the ‘light’ version is right, apart from the fun to build one yourself it will be hard to beat when you start buying parts unless you are a Frugal-phile(tm)

$370 is a bit over the top if you ask me. Sure the salesman will be happy if you buy that one.

/Hugo

28th February 2005, 03:10 AM	#1
Sunsun22 diyAudio Member Join Date: Jul 2004 Location: Hong Kong	How does turntable PSU work? I recently bought a Project RPM 9 turntable. The salesman told me that the Project Speed Box is a MUST option. Other than it can change the speed of the turntable by simply pushing a button, it smoothen the motor rotation by recreating a perfect sine wave from city current and the result can produce a better sound. He lent me the speed box for one week so that I can try it out at home. This speed box is a very small box that cost me only US$59. I tried my turntable with and without the speed box and the different is audible. The violin is silky smooth and it becomes very noticeable when I played the Eagle¡¦s Hotel California. The bongo¡¦s echo is clearly reproduced. There is a more expensive Project Speed Box SE that cost US$370. The box is much bigger with display showing the rotation speed, calibration of speed in steps of 0.1 RPM and a 220V AC 3W outlet at the back. As explained by the salesman, this is a better option because the speed is more accurate, the sine-wave is more perfect and the AC outlet can control other turntable's AC motor provided it consumes less than 3W. However, the salesman is not able to lend me the SE for trial at home. Since the small Speed Box is already good, does it really worth to go for the SE considering such a big difference in price? Actually, I also wish to know how does the turntable's PSU works? Is 3W able to drive most turntables' AC motors? Thanks you

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28th February 2005, 11:54 AM	#2
Netlist diyAudio Moderator Join Date: Jan 2003	To me this speedbox is nothing more then a regulated power supply with variable speed settings. The SE version has the advantage of a display for the readout of the speed. From what I found, the speed can be set more accurate with the SE version. The speed box ‘light’ will (read: should) be as accurate as the SE if its well build, only the SE gives you a better and visualized control. Personally, I think the price of the ‘light’ version is right, apart from the fun to build one yourself it will be hard to beat when you start buying parts unless you are a Frugal-phile(tm) $370 is a bit over the top if you ask me. Sure the salesman will be happy if you buy that one. /Hugo

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