HiVi M5a with Denovo Mini Elliptical Tweeter
13 Liters Bass Reflex Satellite

by Michael Chua

This design is free for DIY. Not for Commercial Use.
This article may not be published in part or full without the express permission of AmpsLab.

Sound of Robin-IIa

The Robin-II is outstanding when supported with subwoofers. As stand alone speakers, they are too dry for my liking.

The Robin-IIa is designed to be used without subwoofers. In this version, midbass is now more pronounced. In "Love Will Keep Us Alive" (Eagles - Hell freezes Over), the bass tracks are loud and punchy. Vocals are still clearly discernible, not muffled by the bass. When "Money for Nothing" (Best of Dire Straits) came on, the drums are fast and the highs don't sound like screeching glass.

Fig 9 below show the changes made to the network. The new Inductor and Capacitor for the M5a midwoofer forces an earlier roll-off, increasing the apparent loudness of the bass in the process. In the Mini Elliptical tweeter, the Lpad was adjusted lightly for marginally higher SPL. To retain the presence in the vocals, the LCR network was removed. Distortion test of the Mini tweeter showed no induced distortion without the LCR (Fig 10).

Fig 9 - Robin-IIa Music Network


Mini Elliptical Distortion - No LCR

Fig 10 - Mini Elliptical Tweeter Distortion (no LCR)
(mic 20 ins Tweeter Axis | 5ms Impulse Window | 1/12 oct smoothing)


Robin-IIa Frequency Response
With the changes made to the network, the drivers cross at 3.5kHz acoustically. This is inline with my original crossover frequency.

Fig 11 - Robin-IIa Frequency Response
3.5kHz 12dB/oct High and Low Pass Networks
(mic 1 meter Tweeter Axis| 5ms Impulse Window | 1/12 oct smoothing)


Robin-IIa Distortion

Fig 12 - Robin-IIa Distortion
(mic 20 ins On Axis with Tweeter | 5ms Impulse Window | 1/12 oct smoothing)


In Conclusion

The Robin-IIa is by far, the best choice for a monitor without a subwoofer. The HiVi M5a midwoofer beats the ZA14 in the bass region. Yet, it extends high enough to be crossed at 3.5kHz without difficulties. I'm suprised that the M5a and the Mini Elliptical tweeter, two reasonably priced drivers, are capable of such high sound quality.

The Robin-IIa - a Must Have


next > Robin | Robin-II | Robin-IIa

Oct 2nd, 2013

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