Just a quick question for you Pro Audio Gurus
I am setting up an Ultimate Pre Amp as a DSP (ADDA and Filters) in a Pro System, you could call it a main speaker management device.
Analog-Precision
Being a newbie and just getting started want to ask how important adding a compressor as a "limiter" is to a live performance
I know I can use the DSP as a master maximum overall volume limit provided there is no clipping on the inputs of the pre amps and somewhat facilitate some reasonable protection of my new old speakers
Speakers JBL Cinema Series 4634M HF and some hand made 21" Twin bass reflex enclosures, amplification, Holton Precision Audio DIY dual monos, x 3, 250 x 2 onto 8 ohms.
First big gig for this rig is in 9 days, 13 performing groups for 6 days, off grid on battery systems and to 400 people.
Thanks in advance for any advice
Photo is of the speakers before the riot and rain protective grills went on
I am setting up an Ultimate Pre Amp as a DSP (ADDA and Filters) in a Pro System, you could call it a main speaker management device.
Analog-Precision
Being a newbie and just getting started want to ask how important adding a compressor as a "limiter" is to a live performance
I know I can use the DSP as a master maximum overall volume limit provided there is no clipping on the inputs of the pre amps and somewhat facilitate some reasonable protection of my new old speakers
Speakers JBL Cinema Series 4634M HF and some hand made 21" Twin bass reflex enclosures, amplification, Holton Precision Audio DIY dual monos, x 3, 250 x 2 onto 8 ohms.
First big gig for this rig is in 9 days, 13 performing groups for 6 days, off grid on battery systems and to 400 people.
Thanks in advance for any advice
Photo is of the speakers before the riot and rain protective grills went on
Attachments
It is always good to have some protection. If you can do brick wall compression(limiting) and set it so that the amps never clip that should provide some useful speaker protection. 250w/ch isn't much for subs but it's plenty for mid/hi horns so you may even consider limiting the amps driving the high end to something less than full power.
Cheers, sure
Interestingly the 250 x 2 's are driving a speaker (bass/low mid) at 4 ohms per channel and real power is more like 1800w to the 4 drivers. There are 4 x 625va Transformers lurking under the covers of the Holtons.
Advice taken though, will definately look at working with compression limiting on those nice new bass speakers.
Filters for those are set as per the build, 24Hz as a HP and 200Hz as a LP.
The 21's were tuned to 23Hz and sound insane in field, 100bB efficient at 50Hz, down 3dB at 24Hz where the Helmholtz resonator stops working.
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Forget using the limiter to prevent amp clipping, set it to prevent excessive power from blowing drivers. But setting a limiter for that is non-trivial. Speakers blow because of excessive RMS power, so you need a fast RMS detector driving your limiter and not a peak detector. You need to know the maximum continuous (RMS) power rating for each driver (couldn't find that based on your data). If you can do an RMS limiter in the DSP (can't tell that either), then work back into the limiting threshold from a calculation of amp gain, input level, and power to the driver. Faster time constants for HF drivers vs woofs. Lacking an RMS-based limiter, you can use a peak limiter, but then you have to calculate the threshold based on a low peak:rms ratio signal (in dB, a square wave is 1:1, a sine wave is 3:1), which will work but technically be based only on peak energy, which will cause it to be overly conservative, but at least protect your drivers.
Nice system.
Curious about , care to elaborate on that?
6 x 250W amps , so assuming some 2500W consumption, time ... what? .... 8 to 12 hours a day? (assuming overnight recharging somwehere else) makes me think humongous battery stacks.
Hey Yea, this is really a delicate balancing act and the first time this rig is to be used to be completely honest. )it is a rather cool system thanks Man I love it to bits(
Still finalising some things before the first Gig.
Have been building this system for a few years to get it to this due to the insane expense
First gig is 400 people, playing over 5 days with 13 ensembles plus speakers
Some are up to 6 piece. We intend to mic up the guitar amps and drum set + run up to 3 fold backs
I managed to get a look at the site today via a video today and thankfully is a wide open field, weather is great this time of year
Now the numbers.
We are capped at 120dB at 1m from a bin and intend to run at about 115 peak majority of the time or less unless asked quietly to arc it up a little.
Thakfully is not a rock and roll or full on DJ Festival.
This will mean that the class A/B amps will be just pottering along at around 100w each for the bins and 20w for the HF
Have done some testing and found the main speakers and amplifier with mixer and some other stuff consumes around 400w, peak, 250 solid
With this in mind the class D/AB/ dual amped monitoring fold backs will not be run loud, just loud enough actually so for the 3 when used for some performances add another 150w
Class A Guitar/bass amps are not that bad either and since mic ed don't need to be run full throttle, so 150 w would go fairly close there.
At end of day if we can cap the load at a Kw, things will go really well on a 550 Ah 24v Gel (BAE tube plate) or 13Kwh @ C10, a 4.2 Kva Magnasign LF Type Isolated Inverter will do the heavy lift at about 90% effiency
Run time after dark, which is about 20:30 here in Tasmania Australia at the moment means at least 10 hours of run on a full battery, mind that;s all the battery.
Lighting being all LED on DMX is set up on a second separated system carrying local area lighting at 190Ah 24v Full River AGM Battery pack which has about 4Kwh of usable power capacity and fairly easily run a little projector and laptop as well intermittently 1000w Inverter
A third system same as the second will be ticking over lighting up an second area with an active speaker, mic and pre.
24v LED Festoon Lighting, for a little added safety and ease of set up.
22 x 270w solar panels will be temporarily set up on site as main generation
an 8 Kva Generator is also going to site to back the main stage PA and operated during the day only, if the weather is ok, not at all.
Phew, makes me dizzy just thinking about it, better get cracking 8 days before the truck rolls and I'm yet to set up the new processor although I have a miniDSP if that doesn't eventuate (which it should)
Being a no drug or beer Festival running mainly "Hippy" music is my saving grace
Thankfully the speakers are stupidly efficient as in 110dB for the HF and 100 or the bass to 30Hz wooo hooo 600 liter Twin 21's Man they are jus soo cool
@upfront is helping with set up so are a few other well respected part time roadies as I couldn't do it alone.
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We'll work it out mate.Dry site
I won't tell if you don't, going to be thirsty work
Thanks for the input, will carefully go over that again, have a good idea what you mean about fast acting limiters though, read the post on the battery power and I think we would both come to agree, the system won't be pushed really. I's more of an experiment gone crazy at this stage, but it is paying enough to keep me interested\\
if interested will post full specifications on the speakers tomorrow. GN ALL
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