Floor Loudspeaker Reviews

Sidebar 1: Bolt Tension Optimization

The Monitor Audio Gold 300 6G has four tensioning bolts, clearly visible along the back of the cabinet. These bolts serve two main purposes: to compress the gasket between the driver and the cabinet to achieve an airtight seal, and to "detune" any resonances in the driver chassis. Designer Michael Hedges cites a third, smaller benefit: additional bracing for the cabinet's back panel—though he insists this has only minimal influence on the sound. After all, the cabinet is made from thick MDF—double-thick in critical spots—and already braced internally.

"Tighten 90° clockwise from just loose 'in contact,' set at room temperature," the instructions advise. "Without a torque driver, we suggest doing the bolt up to the point where it has taken up the strain, and then doing an additional quarter turn (90°)." (One member of the listening panel suggested Monitor include a torque wrench in the box.)

As noted in the main text, we experimented and found that a looser setting—45°, or an eighth not a full quarter turn—resulted in dramatic improvement. The excellence that the Gold 300 was hinting at was now realized. The stereo image was more convincingly grounded. The mild leanness of timbre we'd heard was supplanted by a densely textured foundation. The orchestra was now fully present in the hall, with spacious imaging and fine ambience. The soundstage was better focused, and microdetail and expressiveness were clearly improved. Image depth was rather better, and that elusive quality of natural spatiality was clearly established. Replay was flowing and imbued with richer timbre. Pop and jazz rhythms were more rewarding. We raced around the music library trying this and that, finding win after win.

I have always been aware that loudspeaker fixings can be a source of both imprecision and variability, but I had never encountered a musical effect as great as this.

To increase confidence in this extraordinary result, I ran another blind test, with listening-panel member Charlie Palmer. I used our optimized setting as the control. After my unsighted subject had become comfortable with the sound quality, I carefully and silently tightened the bolts according to factory specification. After just a few bars, he asked what I had done to foreshorten the stereo image, mask detail, and dilute rhythm and expression. "Please change it back at once!" he exclaimed. "I really liked this loudspeaker as it was."

Loosening the tensioning bolts from the factory setting made for a clear and obvious improvement—but perhaps the most important point is that the tensioning bolts make it possible to tune the Gold 300 6Gs, not just tonally but musically.—Martin Colloms