Using a 31 band Eq

EQ guys are using on their cabs/systems. A good starting place if you don't have your own RTA.
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byacey
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Re: finding new and unique ways to screw up

#31 Post by byacey »

Rich4349 wrote:OHH, I'm so dumb. Or ignorant. Probably a hellacious combination of both. I had the multimeter set to AC- AMPS. I saw the "20A" and thought "Oh, that should be safe, don't want to cook the meter...again. (internal fuses) It seems you can only run a couple dozen volts though one of these for a minute or less...

And, after setting the meter to V AC, the XTi produced a whopping 79V- and clipped well as expected. So set the limiter to -3dB, and got about 57V. -6dB got 40.5. So I've decided on -3dB and 6 detents down from max, making 49.5 V. Sound about right? 5 clicks down gives 52.8; still safe but apparently yielding smaller and smaller results.

But the $64 question is: Why wouldn't the XTi clip when I was measuring current, but it will when measuring voltage?
The amp was probably going into protect mode. A current shunt across the amp output terminals is essentially a dead short circuit. It wouldn't take much more than 2 or 3 volts of signal to develop 20A of current across the meter shunt, which is probably .1 ohms or so.
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Rich4349
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Re: Crown 4002

#32 Post by Rich4349 »

Bruce Weldy wrote:
Rich4349 wrote: How much better off would I be using that $750 to build another pair of T-60s or Titan 39s?
Or, you could buy a Driverack and use cheaper amps without dsp.
At this point I don't need an additional amp, I was looking at replacing my Xti4000 with the 4002, so I would still need the dsp it would have.

Does the Driverack do dB increments of 1 dB, like the 4002, or 3,6,12 like the 4000?

And how many separate channels / amps can a single driverack control?
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

Bruce Weldy
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Re: Crown 4002

#33 Post by Bruce Weldy »

Rich4349 wrote:
At this point I don't need an additional amp, I was looking at replacing my Xti4000 with the 4002, so I would still need the dsp it would have.

Does the Driverack do dB increments of 1 dB, like the 4002, or 3,6,12 like the 4000?

And how many separate channels / amps can a single driverack control?
To be honest, I really didn't pay attention to the increments - I just kept turning the knob until the voltage was right. As that was my ultimate goal, I didn't really care about that particular detail.....if I hadn't just put my rack back in the trailer 5 minutes ago, I'd fire it up and check for you.

The driverack PA or PA+ is two channels. It can control as many amps as you daisy chain off those channels. I run mono, so only use the L channel.

As my amps are in the bottom of the rack, I don't want to stand on my head to adjust controls - so, the driverack is easier to use and has more features than the dsp of an amp. But, if all you need is crossover, limiting, and some minor EQ adjustments - it makes sense.

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

Greg Plouvier
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Re: Using a 31 band Eq

#34 Post by Greg Plouvier »

Posted this before but it's good so here it is again:

http://www.m3tools.com/Gain%20Structure ... de0001.htm

The dsp in the 02 series crowns is pretty good. Much better than the original xti, both in features and audio quality.
Greg Plouvier
http://www.magnumcaseworks.com
Protective casing, speaker cabinets, Colorado BF builder, A/V installation, sales, live sound

Rich4349
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Location: Kankakee, IL

Setting Signal chain gain structure

#35 Post by Rich4349 »

"Start with all input and output gains fully down "

So my crown XTi has input gains: the knobs on the front, right? Where are the output gains, or does it have them?

And if I were playing from my pc, I start my turning all of the volume settings to zero?

"Using the oscilloscope, adjust the mixer with a sine wave tone feeding an input channel just below clipping
•Adjust each gain stage of the mixer for a level just below clipping, including the output
•Do the same for each device down the signal chain, adjusting input gain, then output gain"

Will (most) media player(s) on a pc have clipping lights? Or did I follow the signal too far back?
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

brinandi
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Location: MN and beyond

Re: Using a 31 band Eq

#36 Post by brinandi »

Rich4349 wrote:
1) I'm working on figuring out limiting, to keep it under 50v to the Tubas. Does it stay at 50v for 2 Tubas in parallel? It couldn't jump to 100, or most amps wouldn't be able to supply that, right?
I have this question as well..

I read my t-48 plans which state "With paralleled drivers
or cabs voltage is the same across each load, so the voltage limit that applies to one
applies to all."

60 volts max for the 3015lf... run 50 volts safely. When paralleled 50 volts still pushes both drivers to the max safely?

byacey
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Re: Using a 31 band Eq

#37 Post by byacey »

Yes, as long as your amp is capable of driving a 4 ohm load.
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brinandi
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Re: Using a 31 band Eq

#38 Post by brinandi »

OK, thanks! I thought so but just wanted to make sure... Kind of seems counter intuitive to keep the same power/regulation when doubling drivers. Maybe I am just thinking about it too much.. lol... I will be using a GX7 for 4 t-48s (2 per channel) FYI.

Bruce Weldy
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Re: Using a 31 band Eq

#39 Post by Bruce Weldy »

brinandi wrote:OK, thanks! I thought so but just wanted to make sure... Kind of seems counter intuitive to keep the same power/regulation when doubling drivers. Maybe I am just thinking about it too much.. lol... I will be using a GX7 for 4 t-48s (2 per channel) FYI.
The GX7 will handle that just fine.

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

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Tom Smit
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Re: Using a 31 band Eq

#40 Post by Tom Smit »

brinandi wrote:OK, thanks! I thought so but just wanted to make sure... Kind of seems counter intuitive to keep the same power/regulation when doubling drivers..
In actuality, it is not power that stays the same, but rather, voltage. Power is volts times amps. If there are two cabs that are hooked up in parallel (+ve's together, -ve's together), then the imedance is dropped ....... and that means more current will flow ...... which results in more power (watts).
TomS

sine143
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Re: Using a 31 band Eq

#41 Post by sine143 »

I hate the limters on the original XTIs. dunno if I trust em. new xtis seem solid thus far though!
Built:
2x Tuba 30s delta12lf loaded (gone)
4x Otop12 d2512 loaded
8x t48s (18, 18, 24, 24, 30, 30) 3015lf loaded
2x AT (1 mcm, 1 gto 804)
2x SLA Pro (dayton pa6, 6 goldwood piezo loaded)
1x bastard XF208

2x OT212 (delta pro 450a loaded, eminence psd)

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