One thing I noticed when I finished my new solid maple baffles was how the frequency response improved. That project can be found
here. It wasn't so much the material but the way that I decided to mount the Fostex FF165WK. This time I mounted the driver to a 0.075" thick steel plate that virtually eliminated any early reflections both inside the cabinet and outside.
 |
| Using the outside diameter of the plastic bezel on the Fostex FF165WK. The stack height of the 14 gauge stainless and the foam paper gasket behind it created a perfectly flush baffle face. |
 |
| No early reflections inside the cabinet as well. The driver is free to radiate into the cabinet. |
 |
| This is the old baffle design where the Fostex is more traditionally mounted to the outside of the cabinet. This configuration was used in my measurement comparison. |
 |
| This is the new baffle design which was used in the measurements. I'll call this 'Flush Baffle'. |
 |
| Using REW I measured both speakers using the same measurement setup. The purple trace is the old baffle. The green trace is the new 'Flush Baffle' offset by 10dB for comparison. The high frequency horn was not connected. There is no other circuits attached to the Fostex. |
To be sure that my measurements were accurate I performed the same measurements with HolmImpulse software as well. This allows me to see the impulse response as well.
 |
| The two baffles designs shown imposed over one another. |
 |
| Individual measurement of the flush baffle design. |
 |
| Individual measurement of the old baffle design |
 |
| Zooming in on the area of concern after 1 kHz it's more clear. The flush baffle is smoother especially at 4 kHz. |
Conclusion
There appears to be a slight improvement in the frequency response with the flush baffle. Frequency response is only a small insight into the overall sound, and I think there may be other ways to measure and evaluate the effect of reduced edge diffraction, if that is even the issue. Perhaps I need to look at the off-axis response as well. Or maybe I need to take my measurement setup outside for much clearer results. There is also the impulse response to look at as well, which I'm still learning.
As a side note, I decided to measure the frequency response of the new flush baffle design in the listening position 9 feet away. This is the measurement of the Fostex FF165WK with no crossover or baffle step compensation. A few things worth noting. My bass response is strong down to 48 Hz. Also the response is very smooth from 1 kHz up to where is tapers off at 11 kHz. It would seem that all my previous measurements at 1 meter show up the worst results. Listening at 9 feet away allows the overall coverage pattern of the speaker to contribute to what I'm hearing, and Fostex did a good job of creating a well balanced speaker.
|
| FR measurement of listening position 9 feet way. Speaker is half space 6" from the wall. |
Originally published at Crowe Audio.
