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LIMITER

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1 LIMITER le Lun 28 Oct 2013 - 15:09

jhon-sound


Hi, im quite new in the forum, first of all thanks for all this forum is awesome!

Now my problem, i want to limit 2 MHB 4818 loaded with RCF LF18g401 , amp: proline 3000 (2X1100 8ohm and 2X1500 4ohm)

Ive been looking the calculators in this page but im not sure if parameters are correct, my idea is put 2 mhb per channel (4ohm), can somebody tell me if this values down are ok for 2 mhb per channel?, idont know the gain value in dB of this amp how can i know this?




Type charge : Charge ouverte


Puissance HP totale :1800 Watts AES

Impedance totale HP : 4 Ohms

Puissance ampli à l'impédance totale HP : 1500 watts RMS

Gain ampli:¿?(how can i know this value on dB)

THANKS!!!

2 Re: LIMITER le Lun 28 Oct 2013 - 15:58

RIKOIDB


gain ampli: 45.5

3 Re: LIMITER le Lun 28 Oct 2013 - 16:00

RIKOIDB


To calculate amplifier's gain, send a signal to the receiver to 50Hz sine (Room EQ Wizard or any other software). Level is then measured in amp input with a multimeter AC volts position. If the connection is symmetric, the voltage between point 2 and 3 of the XLR, so hot spot and cold spot is measured, but does not use the mass (which distort the measurement). Then without changing gain, the amplifier output voltage is measured. Once the two voltages noted, they fall into this calculator that will give the exact gain

4 Re: LIMITER le Lun 28 Oct 2013 - 16:18

jhon-sound


thanks for quick answer!
im quite lost i understand how to measure volts but i dont know how to " send a signal to the receiver to 50Hz sine"

you mean send to the amp? and how do you know 45.5? is this max gain on proliune 3000? and the last thing is that in this calculators they answer for :
-T.Racks DS2.4 and -DCX2496 but i already have a crossover (behringer cx pro 3400)
should i use T.racks or DCX for xover and limiter? or behringer cx pro 3400 and other limiter (none of these 2) wich will be the better option?
THANKS

5 Re: LIMITER le Lun 28 Oct 2013 - 17:07

Marc34

avatar
definitely, you must use digital limiter in LMS like T.Racks, they are better. LMS have also delay and eq.

T.Racks has a very good RMS limiter, but is limited on eq (not bad at all)

DCX2496 has more flexible eq, but a peak limiter, not bad, but RMS is better.


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Calculatrices Audio Android
Bons plans Thomann

6 Re: LIMITER le Ven 20 Déc 2013 - 20:22

jhon-sound


Hi! i already have my digital processor!! but now I'm quite disappointed about one thing:
-when i calculate the limiter threshold limiter for 2X900 per channel (1800w hp total power 4ohm total impedance and 1500w total amp power) is -11db
-and when i calculate for 1 per channel (900w hp total power and 8ohm total impedance and 1100w total amp power) is -10 db

both with amp gain 45.5

Is this okay? it seems strange to me that i will have to limit less while putting 1 per channel

THANKS!!

7 Re: LIMITER le Ven 20 Déc 2013 - 20:35

Chris Kazvon

avatar
Hi,

if your HP power handling is AES, then we have:

1800WAES @ 4ohms
=> we take 1800/1.53 = 1176.47W "rms"

this is 68.6V @ 4ohms
=38.94dBu

with 45.5 of amp gain, the threshold will be:
38.94-45.5= -6.66dBu

how do you get -11dB ?


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8 Re: LIMITER le Sam 21 Déc 2013 - 1:11

jhon-sound


well i get my -11dB in the calculatrices of this page but it seems id did it bad
it asks you for:
-charge type (i wrote open for mhb 4818)
-total hp power AES (i wrote 1800 in first case and 900 in second)
-total hp impedance ( 4ohm in first 8 in second)
-total amp power (1800 in first and 1100 in second)
and 45.5 amp gain,
what i did wrong?
really thanks!

9 Re: LIMITER le Sam 21 Déc 2013 - 12:53

Chris Kazvon

avatar
My mistake !

You got the DCX ?


EDIT: I mean you made the calculation when using the limiter of the DCX ?


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Chris Kazvon

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10 Re: LIMITER le Sam 21 Déc 2013 - 13:27

jhon-sound


I´m using ds2/4 Thomann limiter

11 Re: LIMITER le Sam 21 Déc 2013 - 14:33

Chris Kazvon

avatar
Sh*t Sh*t Sh*t Sh*t !

Sorry for my first post, made a huge calculation mistake  Embarassed 

Let's go back from how it works Smile

The calculator works this way:

Case 1  Amp Power > 2 x (PAES/1.53) -> we limit the power at PAES/1.53 (this was my first calculation)

Case 2  Amp Power < 2 x (PAES/1.53) -> we limit the power at 1/2 x Amp Power


Here in your first example we got PAES/1.53=1176W, and Amp Power is 1500W, so we are in the second case, so we limit the RMS power sent to the speaker at 1500/2=750Wrms

750Wrms@4ohms is 54.773Vrms, or 36.98dBu.

We limit then at 36.98-45.5 = -8.5dBu

This is the result we got in the calculator SmileSmile
As the 0dB on the T.racks is around +2dBu, the calculator gives then -8.51dBu <=> -12dB on the T.racks !

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Same for the second one:

We got PAES/1.53=589W, and Amp Power is 1100W, so we are in the second case, so we limit the RMS power sent to the speaker at 1100/2=550Wrms

550Wrms@8ohms is 66.333Vrms, or 38.64dBu.

We limit then at 38.64-45.5 = -6.9dBu

Same result as the calculator !!

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And same trick with the T.racks value that in this case is -10dB Smile


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Chris Kazvon

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12 Re: LIMITER le Lun 23 Déc 2013 - 9:38

jhon-sound


wowowowoww Very Happy Very Happy Very Happy Very Happy Shocked Shocked Shocked Shocked 
RRREEAALLLYY REALLY thanks i really wanted to knew this informationn!!! verryy helpful!!!!

13 Re: LIMITER le Lun 23 Déc 2013 - 9:39

jhon-sound


PD: and what will happen with closed charge?

14 Re: LIMITER le Lun 23 Déc 2013 - 15:19

Chris Kazvon

avatar
You're welcome Smile

With a closed charge the speaker does not cool down the way it does with a vented charge.

So instead of taking PAES/1.53 we take PAES/2.5 (if my memory's good) in order to take this cooling problem in consideration.

The rule of thumb is:
threshold closed charge = threshold vented charge - 2dB


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