Setting limiters on Berry LMS

Ah gotcha that makes sense :) sorry for being a bit dim

Usually is yes.

mucsavage wrote: Ah just found this, ---------- Output Specs & Terminals Master Out 1 1 x (XLR) +2 dBu / 600 Ohm 1 x (RCA) +2 dBu / 10k Booth 1 x (RCA) 0dBv / 600 Ohm Record 1 x (RCA) -8dBu / 10k Send 2 x mono (Phone Jack 6.3mm) Headphone Monitor Out 1 x (Jack 6.3mm) -------------- http://www.gereg.co.za/CodeMaster/DJ/DJM600.html Would this be the values for 0dB on the master output?

Yes, I think they will be the output for a 0dB meter reading.

The specs in the manual give the master out (XLR) as 1.23V (i.e. +4dBu) though, not the +2dBu you quoted.

http://www.pioneer.eu/uk/products/archive/DJM-600/media.html

It's the 204 model...

Spesh wrote: This is a good thread. I need to properly set the limiters on my DCX. Having CA18's powering my Labs worries me and I always have to keep an eye on things. Even if I keep the amps out of clip, I'm still not sure whether or not the drivers are getting too much juice.

For sustained musical content with minimal crest factor you need to set your limiters a couple of dB lower than you calculate to relieve thermal stress on the drivers.

If you're using an LMS that works in dBu rather than dBFS (seemingly all of them other than the Behringer) then use this:
http://www.mediafire.com/?n7f4f4110tpf2mu

It's been linked before but seems a fair few people have missed it. It helps you figure out the best attack time for the output's passband too, which is important because if you set your attack or release too fast you can end up with horrible bass distortion - an XTA unit does these calculations on the unit for you, if you want it to, and seems to do a pretty good job of it as well.

I'm going to shamelessly copy this section from page 51 of the DP548 manual, which you can get from the XTA site here http://www.audiocore.co.uk/pdfs/DP548_manual.pdf. It's this kind of thing that separates the top tier of crossover units from good but cheap ones like the DCX in my opinion:

Setting Accurate Limiter Thresholds The limiters built into the are intended to be used for loudspeaker driver protection, as opposed to amplifier protection. All modern professional power amplifiers designed for live sound use have their own limiters, which are tailored to protecting the amplifier from clipping. The following section describes how to set up the units’ limiters to provide exceptional protection against driver overheating, and cone over-excursion. Most speaker systems are given a power rating in Watts RMS. This is the maximum continuous power that the system will handle and often appears very conservative. In reality, as music program is far from continuous in nature, the peak power of the system is much higher – up to ten times the continuous figure. Any limiter, which is to protect the driver from damage, must be able to fulfil the following tasks. • Have an attack time which is calculated to allow transients through but keep the RMS level below the speaker manufacturers specification; • Have a release time which is sufficiently long to avoid the limiter itself modulating the program; • Be intelligent enough to adjust the envelope of the limiter according to the frequency content of the program material. The program limiters are capable of performing all these tasks. The only parameter that the user must set manually is the threshold, and it is crucial that this is done correctly. Consider the table below. dB Ratio Vrms Pwr 8 Ω Pwr 4 Ω Pwr 2 Ω 45 177.83 137.74 2371.71 4743.42 9486.83 44 158.49 122.77 1883.91 3767.83 7535.66 43 141.25 109.41 1496.45 2992.89 5985.79 42 125.89 97.52 1188.67 2377.34 4754.68 41 112.20 86.91 944.19 1888.39 3776.78 40 100.00 77.46 750.00 1500.00 3000.00 39 89.13 69.04 595.75 1191.49 2382.98 38 79.43 61.53 473.22 946.44 1892.87 37 70.79 54.84 375.89 751.78 1503.56 36 63.10 48.87 298.58 597.16 1194.32 35 56.23 43.56 237.17 474.34 948.68 34 50.12 38.82 188.39 376.78 753.57 33 44.67 34.60 149.64 299.29 598.58 32 39.81 30.84 118.87 237.73 475.47 31 35.48 27.48 94.42 188.84 377.68 30 31.62 24.49 75.00 150.00 300.00 Using this table it is a straightforward procedure to work out the required setting of the limiter thresholds for the system.    First, check the RMS power rating of the speaker system, and its impedance. Look up this value in the table above, using the closest value below the rated power of the speaker system. Note the corresponding ‘dB’ value. Check the gain of your amplifier, which needs to be in ‘dB’. Subtract this gain figure FROM that obtained from the table to find the required absolute setting for the limiter thresholds. Note that, for safety, always set the limiter threshold 1 or 2 dB below the maximum allowable worked out using the above method. ALWAYS REFER TO YOUR SPEAKER MANUFACTURER FOR LIMITER SETTINGS.

Unfortunately the DCX doesn't let you adjust limiter attack times, nor does it have automatic envelope adjustment as far as I'm aware. I currently use DBX LMS units, which do tick all those boxes but not on par with the quality of limiting you get from a correctly set XTA. Perhaps this is why people have damaged drivers despite thinking they have their limiters set correctly?

Edited by toastyghost - 24 August 2011 at 4:41am

hollywd901 wrote: still searching for my answer...here are my specs of my system, can someone please help with the limiter...thanks! 2 cabs loaded each with 1 eminence 3012lf speaker says 8ohms and 450 watts rms my amp is a behringer ep2500 says 500 watts rms @ 8 ohms (in stereo mode) input sensitivity of amp says: vRms (@8w) 1.23v (+4.0dbu) anyone's help is appreciated, the more i learn or think i learn, the dumber i feel...

I think is it, open to corrections though:
------------
0 dBu in Ultradrive  = -22dB
to get 1.23v out of the Ultradrive set limiter to -22dB + 4 = -18dBfs = 500W
You want this to be 450W
10 Log (500/450) = 0.4575dB
-18dBfs - 0.4575 = -19.54 dBfs
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