ahhh rental systems and how to prevent damage...there may be technical solutions...but the most effective are strict contract terms such as high priced refundable deposit fee so that you can recoup costs for damage.
if the operator cares at all about what he's doing he'd benefit by not pushing things to the brink even the most well protected system starts sounding gross long before the point of damage is reached.
keeping the gain structure in check or locked out as is possible with many system controllers is the best tool to prevent speaker damage there's no good reason to allow unbridled access to excessive gain or EQ to throw things out of whack.
if the operator cares at all about what he's doing he'd benefit by not pushing things to the brink even the most well protected system starts sounding gross long before the point of damage is reached.
keeping the gain structure in check or locked out as is possible with many system controllers is the best tool to prevent speaker damage there's no good reason to allow unbridled access to excessive gain or EQ to throw things out of whack.
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Then you won’t get anywhere near the system’s potential when being run normally. It will act like a lower power rig. Some operators are just going to turn things up until it is distorting like crazy. Hell, I do it myself for effect. You just don’t let that type of customer anywhere near your good rig. Sometimes you just NEED a “B-rig” that can be turned up until you can’t even tell what song is playing anymore with no damage. Use that one when this type of behavior is anticipated. It won’t sound as good as your A-rig, but sounds infinitely better than a blown one. And if done properly, guaranteed not to quit in the middle of a show.
THAT Corporation Audio Technology, their 215x and 2181are great. Extensive documentation and app notes on there site. Also look at their analog engines. E
I designed this some time ago.
Works with VCA. SSI 2164 is a better new version by Sound Semiconductor. It allows a 10k feedback resistor.
The limiter works with peak rectifiers, very fast
The schematic has some parts left out
View attachment Limiter.pdf
Works with VCA. SSI 2164 is a better new version by Sound Semiconductor. It allows a 10k feedback resistor.
The limiter works with peak rectifiers, very fast
The schematic has some parts left out
View attachment Limiter.pdf
recommend you use DSP for this as you need a lot of compressors/limiters to ensure total protection. I use:
Fast peak limiter (per driver)
slower average power limtier (per driver)
slow medium knee compressor pre crossover that is set to engage just before the other limiters on program material. This is the one that's mostly limiting average volume, it will get quite distorted before the others are engaging, they mainly try and ensure that the drivers are saved.
Fast peak limiter (per driver)
slower average power limtier (per driver)
slow medium knee compressor pre crossover that is set to engage just before the other limiters on program material. This is the one that's mostly limiting average volume, it will get quite distorted before the others are engaging, they mainly try and ensure that the drivers are saved.
There are not many DIY projects for compressors aimed at PA use. I have designed compressors for instruments but the technique is different for PA. It seems you need a near term solution and something like a used DBX zonepro would fit your needs. Yamaha also made some rack mount modules including preamps and digital eq/compressors with remote setup. Another route is multi-effects processors which go for little money, as plugins have taken over. Conventional rack compressor limiters leave the door open for people to fiddle when you are not around.
The DIY part is getting the solution to work with your rig. Deaf mixers are a sad part of life.
The simplest compressor is an opto one using NSL 32SR3. You just need an audio buffer feeding a rectifier circuit providing enough current to drive the LED. A bridge rectifier can be used. It does not need to be precision. You don't even need a filter as the opto resistor stores enough energy, but a cap can be added after the bridge.
The DIY part is getting the solution to work with your rig. Deaf mixers are a sad part of life.
The simplest compressor is an opto one using NSL 32SR3. You just need an audio buffer feeding a rectifier circuit providing enough current to drive the LED. A bridge rectifier can be used. It does not need to be precision. You don't even need a filter as the opto resistor stores enough energy, but a cap can be added after the bridge.
Add an individul limiter at each power amp.
Copy the very simple/cheap one used in APEX amplifiers (in this very Forum), think the 500W amp has one.
Optical LED-LDR type, self triggers when peak signal gets within some 6-8 V from supply rails, avoiding clipping.
Self adjusting so no need for complex calibration, and independent of signal source driving amps.
Cheap and simple, some 5-6 parts total
Here:
You only need: R1 - R26 -the NSL32 Led/LDR optocoupler (which can be DIY with a high efficiency Red Led, a 5mm CDS cell and heat shrink) - D7 - Z3
+VH is the positive rail, OUT is Speaker Out.
There are other optocouplers such as VTL5C but they can be relatively expensive, I always make my own.
EXTRA super important bonus: if you add this inside each amp, (no need for PCB, you can build it on perfboard or a terminal stip) OPERATORS CAN NOT TAMPER WITH OR DISABLE IT.
Copy the very simple/cheap one used in APEX amplifiers (in this very Forum), think the 500W amp has one.
Optical LED-LDR type, self triggers when peak signal gets within some 6-8 V from supply rails, avoiding clipping.
Self adjusting so no need for complex calibration, and independent of signal source driving amps.
Cheap and simple, some 5-6 parts total
Here:
You only need: R1 - R26 -the NSL32 Led/LDR optocoupler (which can be DIY with a high efficiency Red Led, a 5mm CDS cell and heat shrink) - D7 - Z3
+VH is the positive rail, OUT is Speaker Out.
There are other optocouplers such as VTL5C but they can be relatively expensive, I always make my own.
EXTRA super important bonus: if you add this inside each amp, (no need for PCB, you can build it on perfboard or a terminal stip) OPERATORS CAN NOT TAMPER WITH OR DISABLE IT.
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DIY Audio guru-extraordinaire Rod Elliott uses a simple limiter in his complete P.A. project:
Project 137-1
that I think would work quite well for you. Simple, cheap, and effective.
Project 137-1
that I think would work quite well for you. Simple, cheap, and effective.
What wg_ski is referring to is this: the amplifiers discussed so far are pretty small in the PA world. A dramatically under-sized amp driven hard into square waves is very unlikely to destroy anything, but it will also leave a lot of potential performance on the table.
As you want to make more and more use of a given driver, you need larger amplifiers and better limiters.
I'd recommend taking a look at what Powersoft and Linea Research have been up to. Things have really moved on from the days of 400w/ch class AB.
Chris
As you want to make more and more use of a given driver, you need larger amplifiers and better limiters.
I'd recommend taking a look at what Powersoft and Linea Research have been up to. Things have really moved on from the days of 400w/ch class AB.
Chris
Hmmmm....you must not have taken a close look at Rod's design---it's a bi-amp with differential LF outputs. With my slightly bigger supply (38 volts), it'll do 300 watts LF and 50 watts HF. I guess that's small compared to a big class-D amp, but it could blow up many speakers if not for its simple but effective limiter, which can be set as you like.
Hi.
You could look at Yorkville active speakers.
They implement a limiter that appears to be both peak- and "RMS"-limiters.
I think you would need to simulate/test component-values to find a solutions that works for each specific case. Its a complicated circuit. Be prepared to experiment.
Look at NX55p-2 for example. I think the complete service-manual is on their page.
It wont save a speaker in every (torture)-case, but I guess it will do a lot.
Kind regards TroelsM
You could look at Yorkville active speakers.
They implement a limiter that appears to be both peak- and "RMS"-limiters.
I think you would need to simulate/test component-values to find a solutions that works for each specific case. Its a complicated circuit. Be prepared to experiment.
Look at NX55p-2 for example. I think the complete service-manual is on their page.
It wont save a speaker in every (torture)-case, but I guess it will do a lot.
Kind regards TroelsM