[Manny Calavera]

It certainly improved things when I did use it with a Pro-Ject TT.

I then used that TT to upgrade,and then it saw little use.I know one other locally to me that has one,and he raved about the improvements after install.You are the first I have read,or heard of that has put it in a bad light.But I guess everyones ears are different...

 

[Duggeh]

I didn't hear much improvement with my Xpression. A little overall tightening up. Less wobbly edges on prolonged notes and harmonics. To me however the price of the unit is worth it for the fact that I don't have to go lifting up the platter to change the belt anymore. And I own quite a lot of 45RPM. So the convenience boost is much bigger for me than the sonic one.

Really though, I've found it increasingly difficult to listen analytically or critically. I think I'm at or very near the stage of audio contentedness, and might in the coming months condense the rig down to my favourite bits. That'd bring up some monies for a fistful more records. It remains to be seen though.

 

[latinaudio]

Here goes my grain of salt. I recently bought a Project Debut Carbon. Out of the box I was impressed with the depth of the bass and the 
"envelope" of the sound: rich, vivid and what I thougt "natural". On analogplanet.com vinyl guru Michael Fremer talked about the Project Speed Box II as an add on that improves the sound of the table. So I stepped into the upgrade ladder, and bought this tiny box.
First I felt "pretty disappointed with the Pro-ject Speed Box mkII", but then I made the logical move: I compare the table with and without the
Speed Box, and now I understand: Yes, it seems like if the dynamic range is lost but NO, what really happens is that the bass is tighter, less "loose", more precise, so the QUALITY of the sound is better. The treble is less piercing, more natural and maybe you think there is less "air" but  what is happening is that hte treble is sweeter, more precise but less prominent. The midrange sounds "easygoing". 
In my case, the most dramatic change was that I perceived less motor and background sound, which the Project Carbon has specially at the outer grooves. It has been +4 years since the first comment appeared here, but hearing closely and critically let me had the same experience the "pro" writers said. Thumbs up for the Speed Box II !!!

 

[ahou]

There is another problem with Speedboxes as they can stop working - then the speed becomes variable and the sound is, not surprisingly, pretty horrid.