Continuing from the discussion here:
http://www.audiocircle.com/index.php?topic=30522.0It had strayed to a new idea so I am starting this part as a new thread.
The idea was for an omni-directional, free standing speaker to be primarily used as surround channels.
I threw together a test box to see how the drivers performed in this application and to see what the limitations or difficulties might be.
I mounted one M-130 woofer firing straight up and side mounted a GR-T2 tweeter.
I slotted the bottom and made it adjustable to also experiment with a transmission line type loading. I may still go to a single port though.
The off axis response of the woofer was really smooth and mating the GR-T2 tweeter to it was no problem.
The impedance was really flat with a little ripple in the 200Hz range due to a little cavity resonance. I'll have to look into that later.
The spectral decay was really clean too.
Listening revealed something else though. It, like the A/V-1RS design, picked up quite a bit of room gain and on up into frequency ranges to around 1000Hz or so. The vocal area was a little thick and heavy. Taking an RTA (room response) measurement and un-gated MLS response showed it was heavy in the lower end. Measuring a standard A/V-1 setting right next to it confirmed this as well. It was going to have to have a response that was tilted heavier to the top end to have a more balanced room response. I did this with the A/V-1RS as well.
So I re-balanced the response to look like this.
This, like the last posted response, was a gated, 1 watt/1 meter measurement.
Yes it looks hot in the top end and it is at this distance and with no room gain. But the in room responses show otherwise. Listening impressions leave me feeling like it is still just a tad heavy in the 1000Hz and down region.
But, it does sound pretty damn good. It has a big sound to it. Instruments like a piano have a very real sense to them. It played into the room and not at me. I look forward to finding the time in the coming weeks to design a pair from what I learned in this test and finding out just how good a pair can sound.
These may not only be killer good surround speakers but might make good left and right mains as well.
How about this impedance response?
And the spectral decay... Man that is clean.
If I can tweak this to my satisfaction, the kit price will be very inexpensive. It will no more than a standard A/V-1 or A/V-1RS. The only thing that might bump the kit price a little is the addition of floor spikes, but the inductor values get smaller on a design like this and it might offset.
More later.
