Power amp question; sorry if stupid.

[Syyle]

I own a CE2000 Crown Power amp. I am running a subwoofer (2x18 Yamaha) off one channel, and 2 JBL speakers in series (http://www.musiciansfriend.com/product/JBL-JRX125-Dual-15-2Way-Speaker-Cabinet-Pair?sku=600348)

off the other channel.

 

Now, my question is, on the front of my power amp, there are 2 black knobs that I assume are the volumes/gains for each channel. Should these knobs just be maxed out all the time or what; or is there a sweet spot in the levels, like on a tube amp?

 

a small pic of the CE2000: http://www.instrumentpro.com/Merchant2/graphics/00000001/CE2000.gif

[jwlussow]

Those knobs are not an output control, they are an input sensitivity control. They are usually better off NOT being full on. My Crown K1 is usually run about 67% or between 1:30 and 2:00.

[Syyle]

what exactly is sensitivity control? what does that mean? to me, that sounds like gain?

[stvcmty]

1st, good job not bridging the amp into the subs.

 

2nd, what do you mean the JBL speakers are in series? Are they daisy chained or are they run so it is

amp + to speaker 1 +

speaker 1 - to speaker 2 +

speaker 2- to amp -

 

3rd, do you have an active crossover?

 

In general, run the knobs on the front of the amp so the amp's clip indicators do not come on.

 

Stv

[Syyle]

 

1st, good job not bridging the amp into the subs. 2nd, what do you mean the JBL speakers are in series? Are they daisy chained or are they run so it is amp + to speaker 1 + speaker 1 - to speaker 2 + speaker 2- to amp - 3rd, do you have an active crossover? In general, run the knobs on the front of the amp so the amp's clip indicators do not come on. Stv

 

 

i mean the 2 speakers are run like this: amp --> channel 1 to 1st speaker --> 1st speaker to 2nd speaker. that's it.

 

the sub is run: amp --> channel 2 to the sub. that's it. this is correct right?

 

I DO have a crossover, but no idea in hell how to use it or where it goes in the chain of hardware (amp--crossover--mixing board....? and what exactly do I do with the crossover once it's hooked up?).

 

I am quite new to this PA system business.

 

Oh, also, on my mixing board, there are the main fade sliders on the far right side of the board (obviously the main output volume knobs), but right next to it, are 4 fade sliders designating main mix 1, 2, 3, and 4. What are these used for?

[Syyle]

well, cna we first distinguish the pros to having it at full? what does that get you? does it push the full wattage of the amp or what?

[Gregidon]

Okay let's see.

 

The knobs on the front of the amplifier determine how much voltage is coming out of the amp for how much is going in Vout/Vin. The higher you have it, the higher the sensitivity.

 

That being said you should sent the amp attentuators at the lowest setting possible to get the highest output you need. This is because the higher the attenuator is set, the most noise the amp is going to be amplifying (the noise in the signal).

 

Pros and cons to amp being set all the way up:

 

Pros: Getting the full power out of the amp.

 

Cons: Noise is amplified more (hiss is louder in the background)

[Gregidon]

As far as how to set up our system, here's a basic setup

 

Mixer Main Output --> Crossover Input

 

Crossover high output --> Amp input 1 (or A)

Crossover low output --> Amp input 2 (or B)

 

Amp output 1 (or A) --> Top Speakers

Amp output 2 (or B) --> Subs

 

 

Set the amp to crossover around 100 Hz to begin with, this should seriously help your sound.

[Syyle]

 

What is the make and model of the board? Without knowing more, I'd speculate those 4 "fade sliders designating main mix 1, 2, 3, and 4" are possibly sub groups. Sub groups have a number of possible uses, but the most common usage is for adjusting the mix of multiple inputs to the output at once. Example: Assign all of your backing vocal inputs to one sub group (possibly sub group #4). Adjust your individual input strips for the backing vocals to the balanced mix you desire. Then, when you want to bring all of the backing vocalists up or down in the over-all mix, all that is necessary to accomplish this is to raise or lower your #4 subgroup fader... as opposed to individually raising or lowering all the backing vocal input strip faders... because it can be fairly difficult to adjust 3 or 4 or more input strip faders evenly, quickly, and at once.

 

 

yeah that must be it. i accidently had all my channels subbed to these sliders, with all their volume way up, so i was getting ridiculous hum/hiss/feedback when we played. but i turned off all the subgroups, and the background noise was gone, ZERO feedback, and now the amount of volume we can put out as a whole sound, just tripled.

 

thanks for the help.

[Syyle]

As far as how to set up our system, here's a basic setup Mixer Main Output --> Crossover Input Crossover high output --> Amp input 1 (or A) Crossover low output --> Amp input 2 (or B) Amp output 1 (or A) --> Top Speakers Amp output 2 (or B) --> Subs Set the amp to crossover around 100 Hz to begin with, this should seriously help your sound.

 

damn, gonna try that RIGHT now

 

thanks

[Gregidon]

damn, gonna try that RIGHT now thanks

 

Oh course! I hope that it works our well for you!

[Syyle]

okay, i just hooked up my crossover, it's this one right here: http://www.zzounds.com/item--DBX223XL

 

there are some funny options on it that I am not sure what they do. So, how should I go about fixing my input levels and frequencies on both channels?

 

Also, on the back of the crossover, there is a button that Low Sums? What would that do with the sound?

[Gregidon]

Okay. first you need to understand that you are running a mono system, so you just need one side of your crossover.

Pick one, i'd use the left side, but it's up to you.

Set the gain to 0.

Engage the 40hz high pass (your subs really can't produce anything below this anyway.

Set both the high and low outputs to 0 (that's not zero output, that's zero gain).

 

Set the crossover to stereo mode, stereo mode is indicated by the Stereo LED being lit

 

I hope this helps. I've never actually played with that crossover before, but good luck. Start with the attenuators on your amps set low to try to protect your speakers as you play with settings.

[tlbonehead]

 

okay, i just hooked up my crossover, it's this one right here: http://www.zzounds.com/item--DBX223XL there are some funny options on it that I am not sure what they do. So, how should I go about fixing my input levels and frequencies on both channels? Also, on the back of the crossover, there is a button that Low Sums? What would that do with the sound?

 

Is there a reason that you are trying to do this w/o reading your manuals and other good basics to sound and sound setup. Don't they still have the stickie at the top of this forum? It sounds like you really need a lot more than to have a few questions answered here and there. This stuff should all be pretty basic and make sense to you if you do things in the right order. And a lot of it, (where to put certain things in the chain) is pretty much common sense just by thinking about where it would have to be in order to do its job. BTW, unless I have a really good reason, I always set my amp gains wide open.

[twostone]

Lets see amp attenuators is like a garden hose depends how much you need some like a trickle of water some like a moderate stream then there's those who wanted wide open like my self. Never understood why some guys set their amps attenuator like a trickle of water drip drip drip screw that just learn how to set your trim controls and don't add a bunch of BS processors on the front end of the amps.

[Syyle]

 

Okay. first you need to understand that you are running a mono system, so you just need one side of your crossover. Pick one, i'd use the left side, but it's up to you. Set the gain to 0. Engage the 40hz high pass (your subs really can't produce anything below this anyway. Set both the high and low outputs to 0 (that's not zero output, that's zero gain). Set the crossover to stereo mode, stereo mode is indicated by the Stereo LED being lit I hope this helps. I've never actually played with that crossover before, but good luck. Start with the attenuators on your amps set low to try to protect your speakers as you play with settings.

 

 

well, i have to run 2 channel from the crossover though correct? 1 channel for the sub, and 1 channel for the speakers? yes i have one output from the board going into 1 input on the back of crossover, i assume this is correct?

 

okay, i think i have it all nailed down now; and the 40hz high pass is the button on the back that is dubbed "Low Sum"?

[Syyle]

 

Is there a reason that you are trying to do this w/o reading your manuals and other good basics to sound and sound setup. Don't they still have the stickie at the top of this forum? It sounds like you really need a lot more than to have a few questions answered here and there. This stuff should all be pretty basic and make sense to you if you do things in the right order. And a lot of it, (where to put certain things in the chain) is pretty much common sense just by thinking about where it would have to be in order to do its job. BTW, unless I have a really good reason, I always set my amp gains wide open.

 

 

yeah i would read some manuals if i had some. i bought this stuff from someone else who didn't have the original documentation. so i am kind of learning as i go.

[jbutler1982]

No. Low Sum sums your frequencies so that if you only have one subwoofer it doesn't sound wierd - it combines the left and right low frequencies into one single output for those with only one sub.

 

Those knobs should be run full-out at all times. There is no legitimate reason for not running them full open.

[tlbonehead]

yeah i would read some manuals if i had some. i bought this stuff from someone else who didn't have the original documentation. so i am kind of learning as i go.

Did you read the goober's guide at the top of this forum page?

[Syyle]

no i didn't tlbonehead, will do now. sorry if this type of stuff has been asked before. i have just been struggling with this stuff, and wanted some quick answers.

[tlbonehead]

 

no i didn't tlbonehead, will do now. sorry if this type of stuff has been asked before. i have just been struggling with this stuff, and wanted some quick answers.

 

No, that's not a problem. It just sounds like even if you get the right answers on what to do, you still don't have the foundation to understand what you are doing and why you are doing it so that you can make necessary adjustments, etc. You really need this stuff to make sense to yourself if you are going to be able to have any chance at success with it.

[Syyle]

gotcha.

 

well, if you look close at my replies, i was asking what each setting would do, etc etc.

 

the thing i am most confused on with this crossover, is the frequency settings? what technically is it doing when i dial in a certain frequency?

[tlbonehead]

 

gotcha. well, if you look close at my replies, i was asking what each setting would do, etc etc. the thing i am most confused on with this crossover, is the frequency settings? what technically is it doing when i dial in a certain frequency?

 

See, that's my point. There is just too much to need to understand that you would be asking 20 pages of questions. As for this particular question, its very simple. It is just splitting the frequency spectrum at the set frequency on the dial and sending the frequencies below that number to the low outs on the crossover and the frequencies above to the high outputs. Its that basic.

[Syyle]

 

See, that's my point. There is just too much to need to understand that you would be asking 20 pages of questions. As for this particular question, its very simple. It is just splitting the frequency spectrum at the set frequency on the dial and sending the frequencies below that number to the low outs on the crossover and the frequencies above to the high outputs. Its that basic.

 

 

okay, the low frequency setting makes sense to me, should i match it on my high channel side too? because when i do that (set the high channel side to around 100 or so) it gets really muddy, but when i turn it way up, it gets nice and clear.

 

so it seems that there are a bunch of frequencies somewhere that aren't getting sent to either channel? so say the low side is at 100, everything bellow 100hz is sent to the subs, and then i have the high side set to like 500mhz, then all frequencies above that are sent to the speakers, but what about all that stuff in between?

[tlbonehead]

 

okay, the low frequency setting makes sense to me, should i match it on my high channel side too? because when i do that (set the high channel side to around 100 or so) it gets really muddy, but when i turn it way up, it gets nice and clear. so it seems that there are a bunch of frequencies somewhere that aren't getting sent to either channel? so say the low side is at 100, everything bellow 100hz is sent to the subs, and then i have the high side set to like 500mhz, then all frequencies above that are sent to the speakers, but what about all that stuff in between?

 

What crossover is it? There is usually just one center frequency. If you set it at, say, 100 hz, everything below 100 hz will go to the low outs and everything above should go to the high outs. Are you using a 3-way crossocer and skipping one band of the crossover? If its muddy, you need to dial it in.