The Raven-TA is the Time-Aligned version of the Raven. In order to do this, I replaced the tweeter with a Peerless H26TG45-06. As I had hoped, this brought the acoustic centers of the Dayton RS180s and the Peerless H26TG45 to the correct displacement for time-alignment.
Peerless H26TG45-06 Waveguide tweeter
Fig 1 – Peerless H26TG45-06 RAW and High Pass Response. No smoothing applied.
I have never used this tweeter before so it is with a bit of apprehension working with it. I was relieved when I made the RAW measurement (Black Plot). Due to the nature of waveguide, the roll-off below 2kHz shows no diffraction from the front panel. There are however, two notches, one at 2.5kHz and the other at 10kHz. This is caused by surface mounting of the H26TG45. Once I flush mount the tweeter, they’ll smoothen out.
The Red plot is with a High Pass filter. This is a beautiful response. I do not anticipate any issues crossing with the Dayton RS180s.
Crossing the Peerless H26TG45-06 with Dayton RS180s
Fig 2 – Dayton RS180s Low Pass withPeerless H26TG45-06 High Pass Responses.
The Blue plot is of the Dayton RS180s with a Low Pass filter. The Red plot is of the Peerless H26TG45-06 with a High Pass network. Acoustically, they are crossing at about 2.7kHz. The H26TG45-06 should be very comfortable at this frequency.
Raven-TA Time-Alignment Null
Fig 3 – Raven-TA Reversed Null Response
Fig 3 is the response of the Raven-TA with the H26TG45-06 wired in reversed phase. What resulted is an incredible null of almost -40dB deep.
Woofer and Tweeter Time-Alignment Verification
Fig 4 – RS180s and H26TG45 Time Alignment by REW
Fig 4 shows the arrival time of the RS180s and the H26TG45 tweeter. The Green plot is the RS180s woofer with it’s Low Pass filter whereas the Red plot is of the H26TG45 tweeter with it’s High Pass filter. It is clear that the two tips coincide exactly. This is visual proof that the sound from the woofer arrived at the same time as the tweeter. The readouts below the plot verified the time alignment as both the woofer and tweeter registered the same delay of 0.56ms from an Acoustic reference, meaning both sounds reach the microphone at the same time. Measurements courtesy of Room EQ Wizard (REW).
Raven-TA Frequency Response
Fig 5 – Raven-TA Response with Peerless H26TG45-06 wired in-phase. No smoothing applied. Response below 500Hz are in nearfield.
The Raven-TA response is spectacular. It doesn’t deviate more than +/- 3dB all the way up to 15kHz, beyond which it rolls off naturally.
Cumulative Spectral Decay (CSD) Plot of Raven-TA
Fig 6 – CSD Rise Time = 0.1ms, Window = 3ms, Total Slices = 100
Spectrogram of Raven-TA
December 22, 2017Projects