I'll try again, first time out with new OT212s

[brodave2]

I previously built 4 OT12s, two with crossfiring array, and two with melded array. All four had horn flares. I just built two OT212s, no horn flares, again with melded array. The new ones sound great without any eq, the first pair with crossfiring array, need considerable eq to sound good. I have never tried the second pair of OT12s without the first pair, so I don't know how good they sound alone. The first pair I didn't check my piezos, so that might be part of the problem. Also, on the first 4 cabs I put the port too close to the bottom panel, so this might be a problem.
So, I'm really happy that the newest ones sound incredible, but at the same time, now I have to work on the older cabs to see what I did wrong. I want them all to sound as good as the newest ones. I can fix the port problem with the older ones if that would be worth it. I definitely will fix the piezo problem on the oldest ones.
Might anyone have any suggestions regarding why the older ones don't sound as good as the newer ones? All have 2510 12s in them.

[DJPhatman]

Because the older cross-fired use less piezos in the array. You now have first-hand knowledge of the difference between the cross-fired and melded array. It's the reason Bill dropped the cross-fire option in all the plans. The melded is that much better.

As for fixing the older OTops, retro-fit them with a melded array and install the high-pass and low-pass filters in all of them. Then you will never ask yourself if they could be better.

BTW, it's a DeltaLite II 2512, although some users swear by the Delta Pro 12. My personal preference is more, smaller, single-driver, dedicated tops.

[brodave2]

Because the older cross-fired use less piezos in the array.

same number of piezos melded vs. crossfiring

yup, it's 2512, I mistakenly wrote 2510

[camrynekai]

Also the 2 differ by 4 deg in horn flare and 1/2" in horn depth.

[bgavin]

OP, what is your take on the sound quality and loudness?

[brodave2]

OP, what is your take on the sound quality and loudness?

The newest batch sound incredible. All of them are loud. I did some comparisons with the first OT12s I built, compared them to Peavey PR15. Now I need to do some more comparisons, because the new ones sound much better. The first two I built have the crossfiring array, but I did not check the piezos before I built them, so it's completely possible that some of them have reversed polarity. The old ones need eq to sound good, the new ones don't. Also, the old ones have horn flares, the new ones don't. The eq difference doesn't appear to be so much in the piezo range, it's more in the lower mids.

[Bill Fitzmaurice]

Also, the old ones have horn flares, the new ones don't. The eq difference doesn't appear to be so much in the piezo range, it's more in the lower mids.

The added interior volume of the cab with the flares is a bit more, and that will cost a dB or two in the lower mids. Try adding a solid block of polystyrene or urethane foam to reduce the rear chamber volume to compensate.