In this version of the Wren, I replaced the Peerless BC25SC08-04 with a titanium dome tweeter, a DQ25SC16-04. This is the most convenient tweeter to use because they share the same cutout. It’ll be interesting to see whether it’ll change for the better or worse.
Fig 1 – BC25SC08 and DQ25SC16-04 Frequency Response
The Black plot in Fig 1 is the BC25SC06-04 with the High Pass network. The Red plot is the DQ25SC16-04 with the same network. Notice that below 2kHz, the DQ25 has about +5dB more than the BC25.
Fig 2 – CHP70 Low Pass and DQ25SC16-04 High Pass
The Red plot in Fig 2 is the Peerless DQ25SC16-04 tweeter. Let’s see whether the additional +5dB below 2kHz will help with the summation.
Fig 3 – Summing at Crossover Passband
The Black plot is the summed response of the two drivers. Just as I hoped, the passband is lifted to 85dB. How does it compare to the Wren-BC?
Fig 4 – Wren-DQ Frequency Response. Measurements in Nearfield below 400Hz.
Fig 5 – Wren-BC Frequency Response
Fig 4 and Fig 5 is the final responses of the Wren-DQ and BC respectively. It is obvious that in the Wren-DQ, it is flatter from 1kHz~4kHz.
Fig 6 – Wren-DQ Step Response
Fig 7 – Wren-BC Step Response
It is in the step response that we see some startling differences. Fig 6 is with the DQ tweeter. It is worse than the Fig 7, the one with the BC tweeter. What it’s actually saying is the acoustic centers of the DQ tweeter and the CHP-70 is not as close as with the BC. That is understandable because the BC tweeter has a short horn.
Wren-DQ vs Wren-BC
Personally, I prefer the Wren-DQ. The vocals are slightly more forward than the BC version. This doesn’t mean the Wren-BC sounds bad. No, it is just as good. The difference is marginal but for those that prefer to have the vocals more prominent, the Wren-DQ is the one. All other aspects remain the same.
As for the Step Responses, I couldn’t hear the difference. My ears are not that supernatural enough to make out microseconds in acoustic centers.
Peerless DQ and BC tweeter Impedances
A word of caution with using these Peerless DQ25SC16-04 and BC25SC08-04 tweeters. Though their nominal impedance is listed as 4Ω, in reality, it’s 3Ω in use. I verified this when I did an impedance sweep of the Wren-DQ.
Fig 8 – Wren-DQ Impedance
From 3kHz onwards, the DQ starts to dip into 3Ω (Fig 8). This may trigger the over-current protection circuitry in some power amplifiers. When that happens, the treble will sound harsh.
Unless otherwise stated, all measurements were made with the mic at 36 ins, tweeter axis. Impulse Window=5ms. No smoothing applied.
April 28, 2020Projects