System Test and Tune

[racertomtom]

The band’s been pretty busy lately and I hadn’t had a chance to test the complete BF system even though the OT12s have been completed for a few weeks now. I wasn’t under the gun to get it done as my current PA wasn’t exactly a slouch. With no gig this weekend, I set up the complete system in the front yard. I live in the sticks with plenty of room and no neighbors to speak of, so it was time for a test and tune.

I set up 2-24” Lab12 loaded T39s, no V-plate and 2-OT12s 3012HO/NSD2005. I was already running a tri-amped system and will continue to do so. After lowering the mid cross-over to 1.25K and setting the mid limiter, I set the auto eq on the DRPA to the various pre set curves and felt that flat was the best sounding. Lowering the mids seemed to defeat the purpose of the 3012s.

After triple checking everything, I ran straight through 2 channels of the mixer at 0db and the mains at 0db with my cell phone and played Derek Sherinian’s “Czar of Steel”. This is one of my favorites for testing a PA, try it.

I was expecting this system to be a bad ass, but ………I wasn’t expecting it to actually scare me. At first I thought the 12s we distorting a bit (shouldn’t have been) but I was just to close, a few feet. I backed off to about 70 yards before stepping into the pond and thought, OMG! That is F*^#ing LOUD! What am I going to do with four of these things? Of course, I will be running at mic signal levels instead of line levels so it will be tamed quite a bit, I probably had 6db left on the table with recorded music. I not sure there is an indoor venue in my area that can handle what I did. I don’t normal play recorded music at war volume, but to the DJs out there, do you guys actually play this loud?

Shutting down and going in for a drink, my son asked, “ Trying to call the cops without a phone?”

The OT12s are now in the trailer.

[MissileCrisis]

I like my bass at 110 dB, at the listening position. The T60 can do that at like 25 feet away, a pair would get you to 50 ft. I like my highs at 100 dB, so a pair of OT is all I'll ever need to match the bass.

Experience: Hobbyist aka "for fun" DJ.

I like EDM and pretty much whatever I can get paid to play besides rock and country.

[MissileCrisis]

I've never had the pleasure of blasting full volume and seeing how far back I can go before the sound is reasonable. I usually get smaller gigs.

[Tom Smit]

I was expecting this system to be a bad ass, but ………I wasn’t expecting it to actually scare me. At first I thought the 12s we distorting a bit (shouldn’t have been) but I was just to close, a few feet. I backed off to about 70 yards before stepping into the pond and thought, OMG! That is F*^#ing LOUD! What am I going to do with four of these things?

Why, you're going to run them at lower levels, with less EQ, you are.

Shutting down and going in for a drink, my son asked, “ Trying to call the cops without a phone?”

The OT12s are now in the trailer.

Hilarious!

[Michael Murphy]

Yep they do get loud. I want to double my system to 4 T39's and 4 OT12's then Ill be happy at war volume 100ft out. Que, what amps are you running?

[racertomtom]

I like my bass at 110 dB, at the listening position. I like my highs at 100 dB,

That's reasonable.

Why, you're going to run them at lower levels, with less EQ, you are.

That's true. Curiosity got the best of me and I felt the urge to unleash it.

Yep they do get loud. I want to double my system to 4 T39's and 4 OT12's then Ill be happy at war volume 100ft out. Que, what amps are you running?

2 Crown CTS1200 on sub and mids, XLS202 on highs. CTS4200 on monitors, I'd like to have a CTS600 on highs so they would match but I don't need one.

[racertomtom]

The 1st live indoor gig went pretty well, all things considered. The 2:00 pm set up/sound check was cancelled for a poker run/karaoke/auction etc. event and set for 6:00. That turned into 8:00 before opening the trailer doors at a packed house for a 9:00 show, so the sound check consisted of click,click,click go!

We reset the set list so I could have 3 songs to set the PA. (before taking over the drum duties) This was a pretty good venue that I’m familiar with and sounding good is pretty easy. I lowered the guitars a fair amount, took some reverb out of the vocals, lowered the volume of the mid amp and went with basically the same mix, (11 channels) EQ ing the vocals the best I could on the fly. For those keeping score I was running the mains at -7db instead of 0, so the claim that the OT12s have a 6db gain over radiators must be valid. This is also 4 radiators verses 2 OT12s.

From 30 plus feet on, the 3012s/NSD2005s sounded great but a bit obnoxious/harsh any closer. Overall I’m pretty happy with them, especially not having time to dial the system in correctly. I was pleased with how well they reached the back of the venue. I got a lot more than normal compliments on how good the band sounded plus a few, “it’s pretty loud” complaints. I was not over driving the venue, it was very clear, and yes, pretty loud.

I think I’m going to back up a bit and build the next two with melded arrays. Wood already cut. NSDs bought. Here’s the problem. I have committed to a 1.25khz crossover setting by making 6” baffle circles. Should I disassemble the cabs and try to route out to 5”, cross it at 2Khz as is, or should I simply remake the two cabs? I am also considering adding passive crossovers for all four cabs, rather than bi-amping the melded array. I don’t really want to spend money on crossover components, but it would also make the amp box lighter and simplify the system a bit.

Opinions and suggestions would be greatly appreciated.

[miked]

Great review! I had a very similar reaction when testing my 4 OTops (Delta 12LF loaded/2 melded/2 straight) in my backyard, and I was running just one cheap 18-inch radiator sub. The sub was completely overwhelmed, needless to say. Once I let the auto-EQ on the Driverack PA+ do it's thing, I was completely blown away. The OTops are LOUD and clear as a bell. I was on the other side of my yard, a good 50 feet away and if I closed my eyes it sounded like the speaker was just 3 feet away from my face. The air was pressurized, outside, from 50 feet away. THAT is some serious output. They were running 2 per side on a GX500 (700 watts per side @ 4 ohms), FYI.

I am currently building four, 24" T48s with the 3015LF. I'd say they will perk up the overall system output just a tad.

RE: Your new set of cabs. I don't see how you could cut down the phaseplugs from 6" to 5" if they are already installed. You could do an ugly hack job at best, and that's not good. How "done" are the cabs? If the baffles aren't installed already, that makes things easier.

The crossovers were the biggest PITA on my cabs. They are expensive (even just the parts) and add weight and complexity to the build. Being that you already HAVE the processing and amplification needed to biamp the tops, and have already successfully done so on your first pair of OTops, I see no reason to change what is already working for you.

[sine143]

the crossovers are 35 dollars pre assembled... that doesnt seem too bad.

[miked]

True, but I was building 4 cabs and was trying to save some money...this is DIY, afterall.

I have a Driverack PA+ and was seriously debating bi-amping the OTops. My Otops sound great with the spec crossovers, but if I had to do it again, I'd just biamp.

[DJPhatman]

True, but I was building 4 cabs and was trying to save some money...this is DIY, afterall.

I have a Driverack PA+ and was seriously debating bi-amping the OTops. My Otops sound great with the spec crossovers, but if I had to do it again, I'd just biamp.

But, US$160 is a lot cheaper than an extra amp needed to bi-amp the OTops. Also, unless you are not in need of the wide dispersion of the melded array, there is no other valid reason to bi-amp the tops. Building any of Bill's mid-high designs and not using the melded array is money wasted, IMO. US$120 for 4 ASD1001, or US$440 for 4 NSD2005, compared to US$110.60 for 50 Goldwood GT-1016 piezos (enough for 4 melded arrays, with 2 spares).

[miked]

Well, I already had the amps for bi-amping, so that was a non-issue. I built 4 OTops; two cabs with melded arrays and two straight (6 element straight array). Sorry for the threadjack, racertomtom. Back to your thread.

[BrentEvans]

But, US$160 is a lot cheaper than an extra amp needed to bi-amp the OTops. Also, unless you are not in need of the wide dispersion of the melded array, there is no other valid reason to bi-amp the tops.

Valid reasons to biamp:
1. More control of the crossover slope. The passive filters do just fine, but active filters are more precise and sound better just about every time.
2. Control of time alignment between drivers. Admittedly, this isn't as pronounced with the OTop design, but it certainly is with the DRs. Time aligning my DRs made a big difference in the "tightness" of the sound.
3. Current seperation. When you have a high volume low-mid note (like a loud bass guitar or bass synth note), a passively crossed top will have distortion in the HF. HF distortion is particularly noticeable with piezos.
4. Gain structure. The HF and LF section of a cab have inherently different sensitivities. This is normally fixed with a pad of some sort on the HF (Or adding series pairs on a melded array). A biamped cab can have each section optimized, maximizing gain and minimizing corrective EQ which must be applied.

Building any of Bill's mid-high designs and not using the melded array is money wasted, IMO. US$120 for 4 ASD1001, or US$440 for 4 NSD2005, compared to US$110.60 for 50 Goldwood GT-1016 piezos (enough for 4 melded arrays, with 2 spares).

Improved sound quality is not wasted money. The melded array works great for what it is. Compression drivers (and ribbons) characteristically have smoother response. They work better. If they didn't work better, they wouldn't be in the plans, right?

OP... build what will make you happy. My DR200s started out with melded arrays. I liked them a lot, but I wasn't satisfied. I upgraded to ribbons and biamping... and now I'm satisfied. Everyone that has heard both variations of my cabs agree that the ribbons sound way better.

The cost ($150 per cab) was worth it.

[racertomtom]

Sorry for the threadjack, racertomtom. Back to your thread.

Are you kidding? The thread is finally getting interesting. Not at all a highjack.

The passive crossover melded array build is no doubt the cheapest and safest build. Those are not my best traits.

unless you are not in need of the wide dispersion of the melded array,

Interesting, the more I think about it, the wide dispersion is above 2khz which is the least of my worries. I don’t play music as a performance and, more often than not, I am competing with a back line rather than amplifying it. Wider dispersion between 1.2 and 2khz is probably more useful to me. Of course spiraling cabs works well for me too.
I bought my drivers new but pre-owned, so I actually got them cheaper than retail 2512/piezos. Since I was already capable of bi-amping, including cabling, it is probably not worth building passive crossovers and giving up tweaks in the crossover points, filter slopes and volumes.

I think I should give my tops a fair shake and give them a proper sound check. They actually sounded pretty darn good with a 10 minute, during a performance dial in. I think I’ll put another gig under their belt before assembling the other two.

Improved sound quality is not wasted money. The melded array works great for what it is. Compression drivers (and ribbons) characteristically have smoother response. They work better. If they didn't work better, they wouldn't be in the plans, right?

OP... build what will make you happy. My DR200s started out with melded arrays. I liked them a lot, but I wasn't satisfied. I upgraded to ribbons and biamping... and now I'm satisfied. Everyone that has heard both variations of my cabs agree that the ribbons sound way better.

The cost ($150 per cab) was worth it.

I'm already happy and thanks for the reassurance!