Yeah, I know, I just can't leave well enough alone.
So I tried something new on the V-1 prototypes. I removed the rear firing ambient tweeter. Then I cut the back out of the compression driver. So I guess that it really isn't a compression driver any more. Now it is open backed as well.
Then I had to design a new crossover for it. The response of the tweeter didn't change a lot, but with the other tweeter gone I had to readjust everything to balance the impedances back out again. The cap value on the tweeter had to go up slightly to keep the same curve but with more power shunt back to ground on the L-pad.
I needed to drop a little of the woofers upper range down a little to so added an RC trap at the end of its circuit (zobel/impedance equalization).
The frequency response is only slightly smoother but the sound is considerably different. The spectral decay is cleaner too.
The rear tweeter was only adding a little top end air and not playing all the way down to the woofer. Now the main tweeter does play down to the woofer so the rear output is more full range. The phase relationship of the rear output is slightly off from that of the front, but no big dips in the output. It gives a slight but wide band dipped output from about 900Hz to 5kHz. This may actually help the in room response a little for most rooms. There was also one peak in the tweeters rear wave output in the 3kHz range that came up to the level of the woofers output. It appeared to be a function of the throat that was around the diaphragm and surface reflections from the back of the driver. So I cut some little circles out of No Rez and stuck it to the back of the driver. Yeah, it's not exactly pretty, but it did knock down that little peak.
I A/B'ed this one to the old version in mono and noted several real stand out advantages of this opened back version.
With the new version, vocals seemed more relaxed and more detached from the speaker. Piano was cleaner for sure. The old version held each note longer by comparison with a slight trailing edge ring now gone in the newer version.
So I built out the pair and started listening to both of them done this way. This is really special now, even more so than before. The sound stage is now more enveloping. The whole thing is just flat out cleaner and resolution is up a notch over what it was before. These speakers sound even less like speakers and even more transparent. I pulled out a lot of old stuff all over again and actually heard some subtle back ground artifacts in something that I had never noticed before.
Can this get any more fun?
