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Gain Structure

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Lucasdude View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lucasdude Quote  Post ReplyReply Direct Link To This Post Posted: 06 March 2022 at 12:04pm
Originally posted by Aymara Aymara wrote:

So the qsc mx3000a isn't ideal at all for sub? And i heard that you can bridge it at 4ohm, the factory just didn't put it on the sheet.

That's not what I said. It's up to you what you do with your kit, but I suspect that amp will not be happy driving the 2000w 4ohm load you have, either bridged or on a single channel. I also asked you which cabinet type the drivers are in, as this will affect the amps performance. If you drive a subwoofer cabinet below its tuned frequency at high power levels, particularly with an amp with a less than stellar damping factor you can expect problems of the expensive kind.
What sort of crossover or speaker management do you have?


Edited by Lucasdude - 06 March 2022 at 12:05pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fat_brstd Quote  Post ReplyReply Direct Link To This Post Posted: 06 March 2022 at 12:11pm
The MX3000a went on to become the RMX5050a & CMX2000a, both are based on the MX3000a design and all 3 are great amps. Nothing wrong with the MX3000a on bass at all, great tone and decent power for the time is was made. Only issue would be the age of the unit, they will be at least 20 years old now.

The easiest way to fix this is to turn the output gain on the DCX2496 on the sub out channel down so that the amp hits clip when you are the limit of the mixer. You will probably need to set it to something like -12dB for it to work. with the rest of your system.
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Aymara View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aymara Quote  Post ReplyReply Direct Link To This Post Posted: 06 March 2022 at 12:11pm
They are in paraflex O type cabins, it's something new: https://www.facebook.com/groups/bassaz/posts/5102095523138867
And for crossover, it's in my processor (behringer dcx2496), I would cross on 30Hz - 80Hz or something.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aymara Quote  Post ReplyReply Direct Link To This Post Posted: 06 March 2022 at 12:13pm
So on the behringer dcx i need to set -12dB for the sub channel?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fat_brstd Quote  Post ReplyReply Direct Link To This Post Posted: 06 March 2022 at 12:23pm
Originally posted by Aymara Aymara wrote:

So on the behringer dcx i need to set -12dB for the sub channel?


You will need to experiment to find out what is the correct setting but it will be somewhere around -12dB on the sub channel gain. Without having everything in front of me I cant give you an accurate figure, that is something that you have to work out yourself because it is different with every set up. This is part of the gain structure.

The output gains on the crossover should be adjusted so that each section of your system is balanced in sound and that the amps hit maximum power when you have the output from the mixer at maximum.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 06 March 2022 at 4:54pm
Originally posted by Aymara Aymara wrote:

Sorry for al the confusion
My setup is jb systems talent mixer - behringer dcx2496 - qsc mx3000a - void v18 1000
Looks like that mixer only has RCA outputs so what are you using to connect to the DCX.. RCA to XLR cables? If so that is fine but it makes the results you are getting even more puzzling because that mixer probably only produces consumer level(-10db) output levels.. I don't know I can't find a spec sheet. That means you should have the opposite problem with not enough drive signal, so the only possibility I see is that you have the gains cranked up in the DCX.

So.. what are the current settings inside the DCX?

Routing?
Summed mono or stereo?
Input and output gain levels?
Crossover?
EQ?
Limiting?

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Peter Jan View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Peter Jan Quote  Post ReplyReply Direct Link To This Post Posted: 06 March 2022 at 9:05pm
Unless you have your mixer in "red" and/or the DCX EQ boosted, levels at + several dB and things like that, I think the amp is in for a checkup/repair. Knowing those amps and certainly the age they have now, it might be one of the the higher voltage rails/amps of the three stages that don't work for whatever reason. In that case you'll have an amp of a few 100 Watts, which is what seems to be the case here... clipping with barely some input.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aymara Quote  Post ReplyReply Direct Link To This Post Posted: 07 March 2022 at 9:19am
Originally posted by fat_brstd fat_brstd wrote:

Originally posted by Aymara Aymara wrote:

So on the behringer dcx i need to set -12dB for the sub channel?


You will need to experiment to find out what is the correct setting but it will be somewhere around -12dB on the sub channel gain. Without having everything in front of me I cant give you an accurate figure, that is something that you have to work out yourself because it is different with every set up. This is part of the gain structure.

The output gains on the crossover should be adjusted so that each section of your system is balanced in sound and that the amps hit maximum power when you have the output from the mixer at maximum.
 So on the behringer dcx i need to set -12dB for the sub channel?
But if i do that, it's very silent...
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Aymara View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aymara Quote  Post ReplyReply Direct Link To This Post Posted: 07 March 2022 at 9:20am
I don't know how to quote a message so this is a very unclear message haha
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DMorison Quote  Post ReplyReply Direct Link To This Post Posted: 07 March 2022 at 10:29am
Use the "Quote" rather than "Reply" option.....


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Post Options Post Options   Thanks (0) Thanks(0)   Quote DMorison Quote  Post ReplyReply Direct Link To This Post Posted: 07 March 2022 at 10:33am
Re: Setting output level on the DCX: Disconnect your speakers from the amp, play Pink Noise as a test signal, put the output of your mixer where you want it, turn down the output of your DCX until the clip lights on the amp stop lighting up. Reconnect speakers, play normal program material, check the balance between mains and subs - adjust main outputs down on DCX to get good balance with the sub level.
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Aymara View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aymara Quote  Post ReplyReply Direct Link To This Post Posted: 07 March 2022 at 10:49am
Alright i try that when i'm home but what do you mean with "turn down the output of your DCX until the clip lights on the amp stop lighting up"? 
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