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I just joined and a newbie in audio equipment. I am requesting help to set up my audio equipment. Here's my system :
1- Crown XTi2002 power amp (1) - to drive in stereo mode a set of speakers (Wharfedale EVP X215)
2- Cerwin Vega CV2800 power amp (1) - to drive in bridge mode one custom sub
3- Wharfedale EVPX 215 Speakers (1 pair) - 700watts RMS/channel at 4ohms, Freq: 40Hz - 20kHz
4- Custom Sub - 1200 watts RMS at 8ohms, Freq: 35-1500 Hz
5- DBx Driverack PA+
6- DBx 231s Equalizer
I have successfully wired all of above equipment but since I have no idea on the values I need to choose for cross over, compressor limiter, BW/LR types, etc., I need a step by step guide on how to set up properly my system. Here are some more information that I am requesting some clarifications and guidance :
1- I have no RTA mic and when I set up the driverack, I was only up to loading the new preset and not able to balance the sytem with pink noise, RTA mic, etc. How do I do this without RTA mic? FYI, both my tops and sub are not in the preset of driverack? Do I need to bother setting these up?
2- Since I have 231s equalizer, should I just leave "flat" the EQ's of Driverack and Crown amp?
3- I don't have any idea on BW or LR settings and I don't know what level of gains should I input in cross over feature setting of driverack, i.e., from 0db to what?
4- Also don't have any idea on how to set the compressor and limiter features of the driverack.
5- I was told to hook up only to High and Low from driverack. How can I use the mid? Should I buy an additional amp and pair of speakers to do this? If so, what will be the recommended speaker assuming I will just get another XTi2002? I mean the power and frequency range. Or, is there any work around to have this feature with my current equipment's?
6- How do I optimize the powers of my system without clipping or blowing any speakers or amps? I mean from input (mixer) to output which I believe should have relationship on how to use the compressor and limiter functions of driverack.
7- I wish to have different setting for Outdoor and Indoor use. For Outdoor, I will use my custom sub which I prefer to be at Bridge Mode and driven by Cerwin Vega amp. For Indoor, for now, I plan not to use any Sub but just the 2 Wharfedale speakers.
8- I also want to set up my microphone for Karaoke and manage it throu Driverack to avoid feedbacks, achieve good effects, etc.
Sorry for these very basic questions to most of you here and please bear with me this time for my ignorance. Hope somebody can help me provide a detailed set up procedures designed for beginners.
Thanks for your help.
As others have said, this probably isn't the best site to ask about setting up a PA system.
What are you're trying to use the system for? I'm guessing DJ use for parties, weddings, etc.
I'm really not the best person to offer advice on PA setup, but here's a few comments on your questions:
1. You really should get an RTA mic. Otherwise you are "flying blind" so to speak. There is not much point in having a Driverack without one.
2. If I were you I would return the DBx 231, not use the EQ in the Crown, and do any equalization in the Driverack.
3. The best crossover frequency and slope depends on the performance of your mains and subs and how much SPL you need. Generally speaking, you should choose a Butterworth filter if you need an odd-order slope (6 dB or 18 dB per octave) or a Linkwitz-Riley if you need an even-order slope (12 dB or 24 dB per octave). Without knowing anything about the performance of your subs and system usage, a reasonable starting point would be 80Hz LR24.
4. I would not use any compression unless you're finding yourself running out of headroom trying to cover a large area outdoors or something like that. Regarding the limiter, see below.
5. Since you have a pair of passive main speakers and subs, you only need to use the Driverack as a 2-way crossover for the mains & sub. The Driverack can also be used as a crossover for an active 3-way speaker system but that's not what you have so you don't need the mid.
6. If you need to use a limiter to avoid driving the speakers and/or sub over their rated power limits, I think you can do a quick calculation to convert the speaker's maximum watts to dBu based on the speaker's nominal impedance. And then subtract the gain of the Crown amplifier to give you maximum dBu at the output of the Driverack. Do the same for the sub and the C-W amp which will give you a separate value of maximum dBu out of the Driverack. Pick the lower of these two dBu values and set the limiter something like 3 dB below that. I have no experience with the Driverack but in theory this should give you something safe.
7. If you're using the Driverack's auto-EQ, you'll want to measure and use a different EQ setting for each room you put the system in because room acoustics vary from room to room. Same thing if you change the speaker placement in the room. I think for outdoor use, you shouldn't need a different EQ setting for each location. If you do end up using the sub indoors, note the sub level will need to be lower than for outdoor use.
8. I have no experience with this
Thank you for your valuable comments!
Primarily, I am using my system outdoor and yes for DJ and heavy rock en roll playbacks. I am also using it indoor without the sub.
What is SPL?
Can you please show sample calculations for the dBU conversion for limiter settings? My Wharfedale speakers have an RMS of 500watts, peak at 2000watts at 4ohms, 40Hz-20kHz, custom sub 1000watts RMS, 35-1500 Hz.
Sorry for the late reply.
SPL = sound pressure level. I mentioned it in regards to how loud you need the system to play, because the subwoofer crossover settings that produce the best sound quality and probably not the best settings for maximum SPL. You may find for example that using a lower crossover frequency (e.g. 50-60 Hz) and/or a shallower crossover slope provides better sound at moderate levels. But as you increase the level you might end up pushing the Wharfedales into heavy distortion in the bass. If so a higher crossover frequency may give you a little more headroom. 80 Hz LR24 is a good compromise to start with, but I would experiment a bit and see what sounds best.
Here's an example calculation using Ohm's law:
Power = Voltage^2 / Resistance
Power = 500W RMS
Resistance = 4 ohms
Voltage RMS = sqrt(2000) = 44.72V
dBV = 20*log(V)
44.72 Volts RMS = 33 dBV at the amplifier's output
Now subtract the amplifier's voltage gain to get the voltage at the amplifier's input. For the Crown, according to the owner's manual the voltage gain is 32.9 dB. 33 dBV - 32.9 dB = 0.1 dBV
Finally, convert dBV to dBu. 0 dBu is defined to be 0.7746V. 0 dBV is defined to the 1.0V. Converting gives me 2.3 dBu.
That means 2.3 dBu of output from the Driverack will produce 500W RMS output from the Crown amp into 4 ohm speakers.
By repeating the same calculation for 1000W into 8 ohms with the Cerwin-Vega's gain of 35 dB, I get 6.25 dBu. So the Wharefedale speakers are the limiting factor.
Real loudspeakers are not a flat resistive impedance, so the actual output into the Wharfedales won't be exactly 500W. Also, loudspeaker power handling specifications are also approximate, because the stress on the loudspeaker depends on the frequency content of the signal. So if you're going to use the limiter, I would set it a few dBu lower to be conservative, at least until you know your system's limits.
The Live Sound forum on gearslutz.com should get you lots of help.
"A man need merely light the filaments of his receiving set and the world's greatest artists will perform for him." Alfred N. Goldsmith, RCA, 1922
What will be the primary intended use of the room?
Agreed that it looks over complicated for the systems that we typically think of on this board.
Do you have further expectations?
You are in the sound reinforcement arena, that is not the same as home audio. I'm thinking a musician based website would yield more results.
You need to measure and have on-site help! I do this stuff.
The crown XTI does have it's own DSP for crossover and EQ's, compression etc.
But the Driverack duplicates these functions
The Wharfdales have a built in passive crossover - so your job is really just integrating the Sub.
And since it looks like you are doing some outdoor PA work the compression can help with loudness - assuming you are doing a live performance.
I don't know about the performance of your custom SUB (power handling/efficiency etc.
If I were setting it up I'd do out with an RTA and measure the sub performance and limits first. First at "reasonable" levels with the mains running with a 120Hz highpass.
FYI most those here are not Pro Audio familiar (some are) maybe you will get some good advice.
If a recent purchase (drive rack is not a current product) perhaps the seller can give advise.
I say this since it looks like you are in HongKong, I doubt you would like to fly me there and pay for my time....
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
I've forgotten a lot of what I used to know (not really just do as the audio guy said to do) back in my TV days...BUT I do know one thing, and that's not to use any compression if you want great sounding music.
We would compress very dynamic audio because we had to for broadcast and our mandate as editors (this is in the old tape to tape days) was to keep audio below 90%. Compressing the audio this way made it safe for broadcasting to Aunt Millie's 19 inch RCA Victor TV set with a tiny little whizzer cone but killed the dynamics.
So try taking that thing out of the chain.
As far as avoiding feedback, you have to keep the mic level low, or keep the microphone as far away from the speakers as possible. There is probably an optimum microphone level/distance that you can work out with trial and error. (carefully...don't blow your speakers)
Take my information with a grain of salt...I'm just going from dim memories!
I know one of the other innmates can be of assistance to you.
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