|It was in 2010 that I first worked on the Oriole, a 2-way featuring the HiVi RT1C Planar tweeter.
In that earlier build, I settled for a 12dB/oct crossover as I wanted to keep the passive components cost to a minimum. Now, with the Pioneer FH-X731BT, it is a breeze to have steeper crossover slopes and with active bi-amping too.
|Manufacturer’s RT1C-A Frequency Response
Fig 1 is the frequency response of the RT1C by HiVi.
From the plot, we can see that the RT1C starts to roll of at about 3,500Hz. After that, it’s fairly flat from 4kHz to 10kHz. Beyond that, it tapers off to 20kHz (-5dB).
|RT1C Measured Frequency Response
The Black trace in Fig 2 is of the RT1C with a 6dB filter at 2kHz. That can be taken as the natural frequency response of the RT1C.
The Blue trace is at 4kHz with a 24dB slope.
The Red trace is at 5kHz, 24dB/oct.
|Crossing RT1C with Tang Band W5-704
Fig 3 shows the RT1C and Tang Band W5-704 midwoofer crossing at 5kHz (24dB/oct).
I decided against crossing at 4kHz due to the RT1C knee’s rising response. This would have caused a bump when its summed with the W5.
Fig 4 is the summed response of the HiVi RT1C-A and the Tang Band W5-704. Crossover is at 5kHz (24dB/oct). Polarity of RT1C is not inverted. No equalization is applied actively or passively.
The frequency sweep is in Free Space (4pi). Bass is slightly low with the speaker away from the walls. For stronger bass, move the speaker closer to the rear wall (2pi), or bass boost can be applied electronically.
I’m pleasantly surprised at the sound of the Oriole. After I Time Aligned the RT1C and the W5-704, the Oriole is as transparent as can be. Vocal projection is superb. Treble is as expected, wonderfully natural with this Planar tweeter. No harshness. Mid-bass is defined. Not muddy.
Considering the cost of the drivers (RT1C approx $40, W5-704 approx $30), the performance is simply out of this world. This price/performance ratio cannot be met without the Pioneer FH-X731BT. The cost of passive components alone for a 24dB/oct crossover can be as much as the Pioneer itself.