BillFitzmaurice.info

Hey, everyone. Some may remember I started an Otop 12 build while I was stationed in Germany. I think that was in 2015 at some point..... Needless to say I didn't want to spend the extra cash for European equivalents, wait on orders from the States, etc... So I just waited until I got back. So here we are in balmy Minot, ND. I got my 1 car garage workshop put together, and I finished the rest of the speakers. I had to re read the plans several times, locate the proper wood, purchase a drill press, table saw, and ban saw, and it paid off. There are definitely better builds out there, and some worse for that matter. In the end, they're square, air tight, and look pretty good. All I have left to do is put together one more tweeter array and Voila! It's testing time. After the new year I start on Titan 48s.

A few more

A few more

The last ones I have

Hey welcome back!
Both home, and to the forum.

Nice builds.

Just a couple of tiny little things you might like to address.
Take a little more of your damping material away from the vicinity of the crossovers. They might get hot, you don't want fire.
Also, take the damping material away from immediately behind your driver magnets. The magnets are the heatsinks for the drivers, they need a little room to do their work...

Will do, Grant. Thank you for the tips!

Anyone willing to answer an age old question? I want to find the right amp for these 4 Otop 12s. In my previous PA systems I'd get an amp that would do slightly over the Continuous rating of the speakers, this way I never had to worry about blowing them. In this case, I'm using Eminence Delta Pro 12-450a woofers with a rating of 350 watt continuous and 700 watt peak @ 8 ohms. I plan to run in mono with two of these daisey chained to each side of the amp making a 4 ohm load. I've read that the amp should be able to produce the peak wattage of the woofer and I've heard a million other explanations. Based on that logic though, I'd be looking for an amp that will do 1400 watt @ 4 ohms. Anyone see flaws in this thinking?

But then there are voltage limitations to think about. A 1400 watt @ 4 ohm amp would produce ~75 VDC per side. This forum recommends no more than ~35 VDC per cab. With two cabs linked would that mean I'd supply 70 VDC per side? If it's only 35 VDC per side @ 4 ohms then I should only need 306.25 watts. But I feel like I'm missing something....

I run my 4 OTops in mono - 2 per side on a Crown XLS2500. More that enough power and the amp has plenty of headroom.

Take Bruce's advice

You are missing a couple of little things.
Firstly, it's not volts DC, amplifier output is AC. Please remember that.

Secondly, it's a matter of wiring.
Two cabs a side daisy chained (ie parallel wired), sees both cabs getting the same voltage eg 35V, and impedance goes down, you would need to wire the cabs in series to double the voltage, and impedance would go up...

Thanks, fellas. I appreciate the sanity check.

I run my otop12 cd horn units biamped on a crown xls1000 and xls1500 and it’s way too much power barely lights the leds on the amp!!!

ACUA, I appreciate it. Thank you

Alright, I got a DBX Driverack PA2 and a Behringer NX3000D.....both of which are awesome. Just as the plans suggested, I put a 30 Hz tone through them for 12 hours to break them in, all while searching for air leaks with 1/2" clear tubing....no leaks to speak of. After all that I LET 'ER RIP, TATER CHIP!!! Man, these things are the most clear and crisp tops I've ever heard! I put some Jompson Brothers, Skynyrd, Iron Maiden, and Queensryche through them. I followed the suggestions to pull down the 4k but I also found that reducing between 1.25k and 3k helped as well. There's some honkiness that I need to find but all in good time.

I don't think I can ever go back to conventional, front loaded speakers. With that said, I do own a nice set of active JBL PRX 812s and 818s that I use for smaller indoor gigs. I'll probably never part with those because of their convenience, small foot print, and fast set up.

I crossed over the Otops at 100 Hz with. 24dB slope. Does that sound about right?

Good to hear that you find them awesome!

Honkiness may be around 200 to 400 hz.

Bigcox4002001 wrote: ↑Sat Dec 15, 2018 7:27 pm Alright, I got a DBX Driverack PA2 and a Behringer NX3000D.....both of which are awesome. Just as the plans suggested, I put a 30 Hz tone through them for 12 hours to break them in, all while searching for air leaks with 1/2" clear tubing....no leaks to speak of. After all that I LET 'ER RIP, TATER CHIP!!! Man, these things are the most clear and crisp tops I've ever heard! I put some Jompson Brothers, Skynyrd, Iron Maiden, and Queensryche through them. I followed the suggestions to pull down the 4k but I also found that reducing between 1.25k and 3k helped as well. There's some honkiness that I need to find but all in good time.

I don't think I can ever go back to conventional, front loaded speakers. With that said, I do own a nice set of active JBL PRX 812s and 818s that I use for smaller indoor gigs. I'll probably never part with those because of their convenience, small foot print, and fast set up.

I crossed over the Otops at 100 Hz with. 24dB slope. Does that sound about right?

100Hz at 24dB slope? Works more often than not.
Depends, what subs are you using?