Pro-ject speedbox: Is improvement worth the $ ?

Which Graham Slee are you getting Devilboy? We may be able to recommend a cart based on the Slee's specs.

I should have added that I too use a voltage regulator, in this case a regenerator, a PS Audio Premier Power Plant, and even with the Speedbox plugged into that, there was an audible improvement.

"09-02-14: Devilboy
Hmmm. The table will be plugged into a voltage regulator so it WILL see a steady 120V."

No it won't. For that you need a re-generator.

"All of my equipment draws such little power the output always shows 120V in the display, never going up or down even one volt so I should be good there."

Your equipment isn't the real problem. Varying conditions outside your house make the AC fluctuate. If you call The Cable Company they'll send you a demo speed control so you can try it in your system first.

Zd542, the project's motor is an ac sychronous and is not dependent on
stable voltage as the speed is determined my the line frequency. As
previously stated, the 60hz US standard is highly regulated and monitored
and does have the same swing variance as does voltage.

The older PS Power Plants had the ability to both regenerate the ac voltage
and change the line frequency, therefore, they could be used as ac motor
controller, but their line frequency adjustment was too course for fine
adjustments. Both the Walker and VPI's SDS are good examples of a
successful implementation of an ac motor controller.

BTW, voltage regulators (good ones like Furman) do provide 120v stable
voltage. You don not need a power regenerator to produce stable voltage.

The Speed Box offers a feature set that would lower the noise floor, improve resolution, and increase dynamic range: The Speed Box sends the AC input through a regulated and shielded component isolated from the turntable chassis. The AC power supply is off-chassis as well. Add in quartz-regulated speed control and that's a lot of functionality for $129.

Of course the soundstage would be deeper and more delineated, and the bass deeper. Those are the kinds of improvements you get when you keep AC artifacts out of the signal chain and thereby lower the noise floor. It's especially critical on turntables, where the cartridge's job is to amplify vibration. Keep the vibrations you don't want off the main chassis. That's what the Speed Box does.