I get my H-frame ready for measurements, it had D 620 mm.
Green line is nearfield measurement at H-frame opening, red is same measurement FR corrected with dipole rear side radiation (inverted phase and delay), blue is AKABAK simulation for 1 m measurement point from speaker cones. At 71 Hz is H-frame resonance, rest are probably room influences.
Green line is nearfield measurement at H-frame opening, red is same measurement FR corrected with dipole rear side radiation (inverted phase and delay), blue is AKABAK simulation for 1 m measurement point from speaker cones. At 71 Hz is H-frame resonance, rest are probably room influences.
Attachments
Hmmm, looks right except for the blip at 71Hz. If you have built your H-frame with d=620mmm so each front and back tunnel is about L=310mm deep, I do not think that your 71Hz feature is the line/tunnel resonance. This should be a 1/4 wave resonance, and that would correspond to f=0.25*c/L = 0.25*345/0.31=278Hz. If your H-frame is 1.24m long overall, so there are L=0.62m tunnels on each side, then f=139Hz. 71 Hz is well below these values. It's probably a room resonance or something else outside the H-frame itself. I see it in all of your measurements. You could move the H-frame to a completely different acoustic environment (outdoors would be perfect) and do a front-side nearfield to see if that feature disappears. No matter, it's not too severe and I would not worry about it too much at this point. It might be something to investigate later on.
Sorry for the delay. I still not did a impedance measurement with my H-Frame. I had some problems with the w4-1320sj, that i have still to solve.
Hi CharlieLaub,
I now understand better your findings with the bigger drivers. But if i want to use a6 inch middriver between 325Hz -2300Hz, then the offaxis response will be wider at 1,5-2khz and then narrow with the tweeter. Did you have seen this effects horizontal off axis?
Many people like to have a single driver in the 300-3000Hz range. What makes it superior? In a good dipole speaker with a crossover in that range i think only the transient response or the vertical smooth pattern. What do you think?
Do you prefer the neo10 (or grs clone) or 1 cone driver or 2 cone driver in the mids?
