Yeah, the ones I messed with back then were all under-damped to a greater or lesser extent and a few of the cheaper ones had no internal damping to boot, so plenty of internal reflections to muck it up.
Converted to TL loading, even the 'dirt' cheap ones became quite usable enough for the 'market' I was building for, though ultimately I opted for TL loading 'full-range' drivers as wide BW mids/HF from ~350 -7.5 kHz with a woofer, super-tweeter system to cap them off.
With proper TL loading to damp Fs impedance and the 'FR' driver's typically inherently low inductance, I was able to get by with inexpensive 'text-book' XOs sold by various vendors.
GM
Agreed, my understanding of driver/cab relationships tells me that there's only two ideal loading schemes, with OB being the clear winner for covering our acute hearing BW.
GM
Well, I thought the peak wasn't a problem until I removed a fixed 3db 8 ohm Lpad and put a song on with bongos. Yuk, it is awful without the Lpad. I suppose the resistor across the voice coil absorbs emf generated by the resonance and makes a resistance to the cone vibrating on it's own. Too bad, this midrange sounds so nice and coffee can free when not resonating.
I'm gonna give this GM85/8 one more try, by raising the low frequency of the bandpass filter, and if no help, try a 1db Lpad.
I need a clear midrange that can handle 650-8khz. 800 is not low enough because woofer beaming is aparent when crossing a 6db filter there.
Also, it started resonating objects in the room when I had it clear (Lpad on midrange) and high volume, I had to go around removing large objects. That was funny but annoying, I had been blaming the speaker until I figured that one out.
I'm gonna give this GM85/8 one more try, by raising the low frequency of the bandpass filter, and if no help, try a 1db Lpad.
I need a clear midrange that can handle 650-8khz. 800 is not low enough because woofer beaming is aparent when crossing a 6db filter there.
Also, it started resonating objects in the room when I had it clear (Lpad on midrange) and high volume, I had to go around removing large objects. That was funny but annoying, I had been blaming the speaker until I figured that one out.
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Well I have a new laugh line for the old pro's if they don't use it already, The Bongo Baffle. 
I spent a good part of yesterday night and this morning until I realized the driver isn't resonating, the baffle is. And loudly, I thunk around the midrange driver and the exact frequency of the bongos loudly replies. It also shows on some vocals. I need to dampen the baffle, the driver mount, and an 8 inch to 4 inch adapter. I now have a 4 inch midrange where an 8 inch woofer was, a 10 inch woofer where a 10 inch passive radiator was, and a soft dome where the world's worst excuse of a tweeter was.
I spent a good part of yesterday night and this morning until I realized the driver isn't resonating, the baffle is. And loudly, I thunk around the midrange driver and the exact frequency of the bongos loudly replies. It also shows on some vocals. I need to dampen the baffle, the driver mount, and an 8 inch to 4 inch adapter. I now have a 4 inch midrange where an 8 inch woofer was, a 10 inch woofer where a 10 inch passive radiator was, and a soft dome where the world's worst excuse of a tweeter was.What a magic combo. I ended up swapping out the GM85/8 and most of the peak is definitely gone, but still with a small amount, I attribute to the bongo baffle. My 8 inch to 4 inch adapter is hard luan plywood. I was concerned that if I made it from particle board, the woofer would blow it out. I may have blown the driver from crossing too low. But on another hand, if I tap the honker at the dust cap, it has a much lower pitch than the replacement.
That mid driver really raps the baffle hard, with the amp at -30db of 0db.
That mid driver really raps the baffle hard, with the amp at -30db of 0db.
In order to get closer to the original topic, here is some inspiration to avoid blaming the closed back driver design until you do some serious tests. In my case I had a Twilight Zone combo of the driver resonant peak (at max Z), a baffle that resonates at bongo frequencies and lower vocal tones, AND a bad driver that was damaged in shipping. The frame was bent and I straightened it, used it for initial tests, and forgot to replace it. Add in one lower midrange bandpass frequency adjusted from 650hz to 1000 and it's all fixed except for some remnant bongo baffle.
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That Walmart Salsa Bowl makes a nice 5.25" midrange chamber when specially filled with no itch fiberglass. An outer layer 1/4 inch thick normal density, then puff some out and fill the void. After the driver broke in, it's doing much better. Being so tight must have caused to to be really snappy on the transients, so much so that it easily knocked the cabinet wood. A bit softer now but overall better sounding.
The bowl is a thick low resonance, maybe polypropylene plastic, A bit too small but good enough. The idea is to hold me off until I get some much better drivers. I previously used book shelf speakers and a sub woofer. That really doesn't work so well, too much program material is lost and stuffed in the middle by it's self. 10" three way is good for me now, but I may make a set of 12" three ways with the better drivers.
The bowl is a thick low resonance, maybe polypropylene plastic, A bit too small but good enough. The idea is to hold me off until I get some much better drivers. I previously used book shelf speakers and a sub woofer. That really doesn't work so well, too much program material is lost and stuffed in the middle by it's self. 10" three way is good for me now, but I may make a set of 12" three ways with the better drivers.
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