The Dove is based on a Dayton 7″ aluminum cone midwoofer, the DA175-8. I’ve never used her in a bass reflex before, so this is going to be a first.
Fig 1 – Dayton DA175-8 RAW Frequency Response • Baffle Width=8-3/4″
The RAW frequency response of the DA175-8 is in Fig 1. I hesitated doing a 2-way because of the early roll-off. It looks like she’s going to need a tweeter that can cross down to 2kHz. Not many dome tweeters can be crossed that low. It’s not an issue with my Seas 27TBFC but she’s almost double the cost of the DA175. For this project, I rather use a budget tweeter and I found one in the Peerless BC25TG15-04.
Fig 2 – Peerless BC25TG15-04 RAW Frequency Response • Baffle Width=8-3/4″
The Black plot in Fig 2 is the RAW response of the BC25TG15 when she’s surface mounted in my 15 liters box. The destructive effects of baffle diffraction can be clearly seen.
The Red plot is with the BC25TG15 flush mounted. The difference is stunning. Gone are the peaks and valleys. She is now flat with only a slight bump at 1.5kHz. Imagine, a $15 tweeter doing this. The BC25TG15 must be one of the most under-rated tweeters around.
Fig 3 – Dayton DA175-8 with Peerless BC25TG15-04 (Flush Mounted)
Now that I found the right tweeter, the next step is to see how well they get along. The Blue plot in Fig 3 is the DA175 with a basic low pass filter. I’m encouraged to find the cone breakup is well subdued without me having to use a notch filter. The Red plot is the flush mounted BC25TG15 with her high pass network. The two drivers are crossing at 1.6kHz.
Fig 4 – Dove Crossover Passband
The Black plot in Fig 4 shows the summation at the crossover. It looks perfectly fine as no cancellations are seen.
Fig 5 – Dove Frequency Response
Fig 5 is the final frequency response of the Dove. This is my fifth and final attempt. In my previous versions, the response was flat but the Dove failed to engaged me. I then threw caution into the wind and tuned her by ear. Now she sounds beautiful.
Fig 6 – Dove Null
The Violet plot in Fig 6 is with the tweeter wires in reversed phase. It resulted in a symmetrical null centering at 1.6kHz. The depth is not 40dB deep but is good enough. I didn’t make out any phasing issues during auditioning.
Fig 7 – Dove Nearfield Frequency Response
Fig 7 is the Dove response with a nearfield response spliced in at 500Hz (Blue plot). Notice the ugly notch at 150Hz is no longer there. That’s a floor bounce picked by my microphone. The nearfield response is an approximation of an anechoic measurement, that is without any room reflections.
Fig 8 – Dove Port Output
The Brown plot is the back port output. The microphone was inserted about 1/4″ into the tube for this measurement. There is a pipe resonance at 900Hz but it is well below the fundamental to cause any harm.
Fig 9 – Dove Step Response
The Step response of the Dove is in Fig 9. There are some jaggedness at the lower tip. I believe they are caused by the slight misalignment in the crossover. The transient is quite normal for a woofer of this size. The woofer hits the apex at 400 microsec. She’s not a “fast” woofer so I can expect the tempo of the DA175 to be ordinary.
Fig 10 – Dove Waterfall
Fig 11 – Dove Toneburst Energy Storage
The Waterfall (Fig 10) and Toneburst (Fig 11) plots are quite impressive in that they show very few artifacts in the treble.
Fig 12 – Dove Spectrogram
The Spectrogram (Fig 12) recorded a streak at 1kHz. It is benign. I did not pick up any smearing during playback. No other excess energy are shown.
Fig 13 – Dove Box Modeling
I tuned the Dove (Fig 13) like in the Soliloquy-IIb. Her bass reflex alignment is Under-damped. It’s mainly due to the DA175 highish Qts. With this tuning, I am trading the bass tightness for +3dB in loudness. If I want a better transient, I need to resort to a sealed box and target a closed box Q (Qtc) of 0.707. That would mean a much larger box. Maybe another time. Right now, it’s a 15 liters bass reflex.
Fig 14 – Dove Impedance
The impedance of the Dove is 8Ω nominal (Fig 14). She is an easy load for power amplifiers. Most of the time she’s above 6Ω, only dipping to 5Ω at 20kHz. Her electrical phase is almost linear. At the lower end, the box tuning is about 44Hz, close to what is predicted in the box modeling.
Summary of Dove
The Dove is one of those rare occasions where a speaker not only measures flat but sounds great as well. Her bass is loud and fairly detailed. There’s excellent separation between the bass and the midrange. Vocals are not drowned out by the music. Neither is she too shouty. The treble has the right amount of sparkle without being brittle or harsh.
This is only possible because of the Peerless BC25TG15-04. She allowed me to cross the Dayton DA175-8 at 1.6kHz. If not for that, I wouldn’t have been able to use the DA175 in a 2-way.
In the end, the Dove delivers incredible sound quality for very little money. The DA175 is only $30. The BC25TG15 is half that, at $15. I am so pleased with the Dove that I rate her one of my best “budget” 2-way. Highly recommended.
Unless otherwise stated, all measurements were made in Full Space (4 pi) with the mic at 36 ins, tweeter axis. Impulse Window=5ms. No smoothing applied.
March 3, 2021Projects