Learned a lot; still need amp/speaker matching help
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Posted on Jul 13, 2009 07:06 pm
SolidRocker
Music Loving Hack
Member Since: Jul 13, 2009
Hi guys. My first post here. I have been reading for about 2 hours and have learned a lot. I think I have my sytem matched about right based on some previous posts but have too much $$$ tied up to screw it up. My basic set up is as follows:
Board: Allen & Heath Mixwizard 16:2dx
Amp for subs: Crown 4000 xti (1200@4ohms)
Amp for Mains: Crown 2000 xti (475@8ohms)
Amp for Monitors: Crown XLS-402d (300@8ohms; 450@4ohms)
Subs: Pair of Peavey SP118X (4ohm) (500 continuous; 1000 program; 2000 peak)
Mains: Pair of Peavey SPG3 (350 continuous; 700 program; 1400 peak)
Monitors: Up to 4 JBL JRX112M 250@8ohms
Crossover: BBE MAX-X3
The Crown 4000 xti is new and has not been used yet. If I understand some of the other posts, I should be OK from a matching standpoint because my amps are not exceeding the peak wattage and are near the program wattage. Should have plenty of headroom and will not clip. So that is my first question - did I read that right?
Second question is how will I know if I am over-driving the speakers? Can I use the ear test and wait for audible distortion?
Third and final question (at least for now), has to do with the cross over. The back of the SPG3 has input for full range and for bi-amp high (also has bi-am low, but I don't use). When I run from the crossover to the amp to the tops and plug into the bi-amp high, I seem to loose all my mids (I think it defeats the 15" in the cab). When I run into the full range, it sounds much better but I keep thinking I'm not doing something right. Could I have the crossover set up wrong?
Thanks so much for your help. There is a special place in heaven for guys like you who help guys like me.
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Jul 13, 2009 09:23 pm Hey SolidRocker.
Nice system your putting together there. And you have a lot of power to run it.
So, on your first question. Yes! You are correct. You have plenty of headroom and your amp and speakers are a very good match.
On your second question. Yes. You will hear an audible distortion coming out of the speaker if you over drive them.
On your crossover. I have a question for you. With two XTI amps, why are you using an BBE?
Inside each of the XTI, is DSP. One part of the DSP, is a crossover network. And a very comprehensive one at that. You can set the amps to run the speaker that you want, with no other connection needed.
All you need is, a computer, several Ethernet cables, and a copy of the Crown High IQ software. Which comes free with each of your amps.
Now you still can use your BBE if you wish. But, I think that you will find the XTI crossover will sound much better.
For your problem with the BBE making the 15" disappear, I think that it might be in a three way mode, as opposed to a two way crossover.
This would explain the issue that you posted. But, without seeing it in person, this is just a guess.
The only other thing that would cause that, is the unit is set wrong. You may have to pay attention to the selector switch. Weather it's a multiply, or divide switch. Those switches have gotten me before. I thought I was dividing, when in fact, I was multiplying.
So, I thought I was at 1k, when in reality, I was at 10k. And at 10k, you only get the smallest little squeak out of the PA.
Double check your settings. To start with, I think that you want to start the tops at around 120 hz on the HPF. And 120 hz on the LPF filter for your subs.
Give this a try. See if it's what your looking for in your system. Then try it with the XTI amps. Do an "A/B" comparison. See what you think.
Jul 13, 2009 10:11 pm Hey Rob - Thanks for the post. I will have to do some more research on the xti. I knew that it had crossover capability, but thought that it sent the lows to channel 1 and highs to channel 2. If that is the case, seems like I would have left side on the 4000xti and the right side on the 2000xti. However, if i can still run both lows out of the 4000 and the highs out of the 2000s and skip the BBE, that would be great. I'll jump on and do some research. That would make it an even better amp than I thought.
Jul 13, 2009 10:25 pm Yeah, I think that you can do both.
Either the lows out of 1 and the highs out of 2.
But, you can set the filters any which way you wish.
So, you can match the filters for 1 and 2, so that way, the 4000 is the subs. And the 2000 is the highs.
Jul 18, 2009 08:47 pm Rob,
I got the amps set up so that the 4000 is running the lows and the 2000 is running the top cabs. The programmable part of the xti is pretty nice.
Based on reading the spec sheets on the subs and the tops, it appears that the best crossover is at 125hz. I'm also phasing out the bottom below 33hz because the spec sheet says the useable low frequency is 31hz.
The question that I have is what kind of delay (if any) I should be programming in (delaying the highs, I think, so the bass can catch up). The crown presets for subs don't have any delay included. My typical set up is with the subs on the floor with the cabs on a stand right by them.
Any thoughts?
Thanks
Jul 20, 2009 01:51 pm Normally, you don't delay subs. Your delay the tops back to match the subs.
If you don't have some program to see where the drivers are at in time, then you have to just rely on just your ear.
Smaartlive is one of the few programs out there that will measure delay. But, the new Spector fu may, I'm not to sure on that.
I don't think that it is critical for the size that you at right now to worry too much about delay.
The only thing that I would suggest, is to measure to the drum kit from the center of the stage. Then set the input delay to that measurement.
That way, if your not putting up overheads, the cymbals will sound in time with your system.
