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Limiting amplifier output via LMS

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Futendra View Drop Down
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    Posted: 18 May 2017 at 11:15pm
I want to limit the output that goes out of our DCX2496, so we would never be able to to blow our drivers by driving our amplifiers too hard.

We will be using a Behringer Europower EP1500 and a TSA 4-1300 to power our TMS-3s.

2" HF Driver:
RMS: 75W
Impedance: 16 Ohm
Calculated ideal amp power: 16 Ohm 120W / 8 Ohm 240W
Amp we will be using: Behringer Europower EP1500
Amp power: 8 Ohm 260W

2x 10" MF Driver (Calculated together in the manual):
RMS: 200W
Impedance: 8 Ohm
Calculated ideal amp power: 8 Ohm 320W
Amp we will be using: TSA 4-1300
Amp power: 8 Ohm 1220W

2x 15" LF Driver (Calculated together in the manual):
RMS: 500W
Impedance: 4 Ohm
Calculated ideal amp power: 4 Ohm 800W
Amp we will be using: TSA 4-1300
Amp power: 4 Ohm 1670 W



How do I do this correctly?


Edited by Futendra - 18 May 2017 at 11:16pm
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Conanski View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 18 May 2017 at 11:56pm
First You have to figure out what the gain differences are going to be between the drivers because it's likely the HF will totally overpower the other two acoustically if run at the same gain. This is where the driver efficiency factors in, a 2" CD on a horn could have a 1w sensitivity of 108 while dual 10's might only do 102dB so the CD gain will have to be 6dB lower than the mids to produce a balanced output... assuming the the two amplifiers have the same total gain as well. Do they?  EQ could also change this slightly but readjust again after you get the the system into the right ballpark.

How are you determining that "ideal amp power"?
Is that 200w RMS for the mids per driver of for the pair?
Same question for the LF, is that 500w for a single driver or the pair?

In either case why is the ideal less than 3dB above RMS? Is this for an EDM system or something? If it is then that is cool.. you want to limit a little over RMS but for other types of music the limiters could be opened up quite a bit.


Edited by Conanski - 18 May 2017 at 11:59pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Futendra Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2017 at 12:30am
Originally posted by Conanski Conanski wrote:

First You have to figure out what the gain differences are going to be between the drivers because it's likely the HF will totally overpower the other two acoustically if run at the same gain. This is where the driver efficiency factors in, a 2" CD on a horn could have a 1w sensitivity of 108 while dual 10's might only do 102dB so the CD gain will have to be 6dB lower than the mids to produce a balanced output... assuming the the two amplifiers have the same total gain as well. Do they?  EQ could also change this slightly but readjust again after you get the the system into the right ballpark.

Driver gains:
HF:
-2 dB
LF:
0 dB
LMF:
-2dB

How do I find out if the amplifiers have the same total gain? I'm a bit confused

Originally posted by Conanski Conanski wrote:

How are you determining that "ideal amp power"?
Is that 200w RMS for the mids per driver of for the pair?
Same question for the LF, is that 500w for a single driver or the pair?

Ideal amp power is 1.6x RMS wattage. This is usually under the program wattage. We determined it this way because we are going to play harder genres.

I think the wattage is for a pair. Not sure though, here is the manual: http://www.kirsch-akustik.de/downloads/tms3.pdf

Originally posted by Conanski Conanski wrote:

In either case why is the ideal less than 3dB above RMS? Is this for an EDM system or something? If it is then that is cool.. you want to limit a little over RMS but for other types of music the limiters could be opened up quite a bit.

It is for harder genres. Tekno, hardcore, breakcore, terror, acidcore, ...


Edited by Futendra - 19 May 2017 at 12:36am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2017 at 2:59am
Originally posted by Futendra Futendra wrote:


Driver gains:
HF:
-2 dB
LF:
0 dB
LMF:
-2dB
So both mids and highs are -2db down from the lows.

Originally posted by Futendra Futendra wrote:

How do I find out if the amplifiers have the same total gain?
Should be in the specs.
Originally posted by Futendra Futendra wrote:


Ideal amp power is 1.6x RMS wattage. This is usually under the program wattage. We determined it this way because we are going to play harder genres.
OK.

Originally posted by Futendra Futendra wrote:

I think the wattage is for a pair. Not sure though, here is the manual: http://www.kirsch-akustik.de/downloads/tms3.pdf
Yeah looks like it is for the pair.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Futendra Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2017 at 1:27pm
Can't find anything about total gain in the amplifier specs...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2017 at 2:54pm
Originally posted by Futendra Futendra wrote:

Can't find anything about total gain in the amplifier specs...


Yeah it is in there.

T-amp TSA-4-1300
Input sensitivity: 0.775v(0dB)/1.4v(5.1dB) switchable
Voltage amplification(gain): 37.8dB

Behringer Ep1500
Input sensitivity: 1.14v(3.4dB)
Voltage gain: 32dB

Looking at the input sensitivies for a moment, what this means is that if you were to connect the amps directly to your mixer you would need to push the main output to +5dB to get the t-amp to full output(when it is set to 1.4v sensitivity), while the Behringer would only need +3.4dB for full power.
But you don't want full output from the t-amp you want roughly half or 3dB less than full so that number drops to +2.1dB on the mixer.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Futendra Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2017 at 3:25pm
I don't understand much of that. Math has never been my best skill.
We will be plugging the amps in the DCX, of course.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote APC321 Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2017 at 6:13pm
A simple non-technical check to see if you have done things right:

1) Get the DJ mixer that you will be using with your rig.

2) Connect it up to your LMS and amps. Do not connect the speakers.

3) Play some tunes through the DJ mixer and max out all the eq, and red line the masters on the DJ mixer.

If none of the clip lights light up on your amps (or just flash occasionally with the music on bass or sub) then you will be fine.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Futendra Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2017 at 6:43pm
Originally posted by APC321 APC321 wrote:

A simple non-technical check to see if you have done things right:

1) Get the DJ mixer that you will be using with your rig.

2) Connect it up to your LMS and amps. Do not connect the speakers.

3) Play some tunes through the DJ mixer and max out all the eq, and red line the masters on the DJ mixer.

If none of the clip lights light up on your amps (or just flash occasionally with the music on bass or sub) then you will be fine.

It's not really about making redlining safe, we want to make sure we won't blow our drivers, because the amps we are using give quite a lot more power than necessary.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 4D Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2017 at 8:21pm

Think about use the input gain on ab & c inputs, and output gains on the six outputs for setting the gain structure correctly to maintain dynamic range without overpowering the speakers or driving the amplifiers into clip and then use the limiters as a final brick wall.


https://musicgroup-prod.mindtouch.us/04_BEHRINGER/How_Do_I_Set_Up_My_DCX2496_Unit%3F










Edited by 4D - 19 May 2017 at 8:50pm
DMZ. "The bass was intense. Girls were literally running up to stand next to the subs"
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Futendra View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Futendra Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2017 at 8:34pm
So if I set the LMF and MF output to +2.1dB gain on the DCX, I will actually be safe when driving the amps "full power"? Or what does that mean?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Futendra Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2017 at 8:37pm
So I should set the LMF and MF gain to +0.1dB (in order to have the right balance + restricting the wattage output of the TSA 4-1300) and set the HF to +3.4dB (for actual full power on the EP1500)?
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