Yamaha YSP-1 Measurements

It was fairly easy to measure the YSP-1 outside in free air. For the 4.5" mid-woofer I did a close mic'ed measurement while the YSP-1 was pointing straight up. This gives a reflection-free curve with no curve-smoothing required. With the software set at 80Hz for the crossover the woofer curved out as seen below. Note how sharp the digital filter cuts off the mid-woofer at 1000Hz!

Please don't get too excited by the 114.5dB (average) SPL reading. This SPL is with the microphone almost touching the woofer cone so SPL readings are inaccurate. The woofer itself appears quite linear, ±1.25dB. It is -3dB at 68Hz which is very good performance for such a small driver. When moving the internal crossover up to 100Hz this 4.5" driver will stay more linear at higher power levels than if the crossover were kept at 80Hz. Listening tests (below) confirm the validity of the 100Hz, crossover-to-subwoofers choice.

The graph below indicates the left channel frequency response for the system in Stereo mode. As can be seen in the upper microphone-speaker photo this measurement was taken with the mic 8" above what was assumed to be the left channel 1.25" speaker cluster.

From 200Hz and below you're seeing the response of the 4.5" woofer, which, at this measurement position, is about 12" away and at a 45º angle from the microphone. Note that the curve from 200Hz to 1000Hz is quite a bit choppier than the close mic'ed curve of the woofer only. This might indicate that the 1.25" "steer-able" drivers are brought down and overlap the woofer's frequency response in this range.

Normally such a frequency overlap is a no-no with hi-fidelity speakers made specifically for music reproduction. But the guess here is that the overlap helps with effectively implementing the Beam Tone mode, using the larger piston area of the 4.5" drivers in conjunction with the little 1.25" drivers when, for instance, +5dB of bass boost is dialed-in.

To finish up this curve, note that with all tone controls set to flat the 1.25" drivers exhibit a 5.5dB average bump centered at 6100Hz. The response does extend out fairly well to almost 15KHz but with the 6100Hz peak presence these upper frequencies are more likely to be obscured rather than heard if no attention is paid to attenuating the treble response via the internal treble Tone Control.

The final curve is a splice, at 1000Hz, of the composite woofer and tweeter curves. In this case the internal Tone Control was used to set the tweeter level to - 3dB. This setting yielded the best overall frequency response for the YSP-1.

This type of smiley-curve response is most comfortable to hear when listening non-critically to music and will usually be perceived as more than adequate treble extension within the context of TV or movie viewing. Also, the bump at 6100Hz most probably corroborates well with frequencies beginning lower, at around 3KHz in rendering the "floating-in-space" sound portrait the YSP-1 is capable of rendering.

The caveat to the 6100Hz peak is that with movie music not specifically re-EQ'ed for DVD, instruments with lots of high frequency harmonic energy, like a tambourine, become immediately fatiguing. The same holds true for the CD and most music-only formats. As it is, the YSP-1's frequency response appears to have been specifically tailored to achieve maximum beam- throwing efficiency as is hinted by the inclusion of the multiple-frequency polar pattern chart contained in Yamaha's YSP-1 white paper.