ok -- one thought for you. scott (screamersusa) runs a 6x10 compression opening in front of his 3015lf's in his fury sub, and runs it hard... real hard. Says he doesn't feel comfortable running his TH without a bit of compression.
Even in my insanity tests on my ss15's, I've not damaged a cone. Smelled a bit of vc glue getting warm, but not a cone issue.
Arts Suggestion still seems the best way to set this.
If you need to start somwhere here is an guess.
The PL380 can produce 1500W into 8 ohms (110V)
Djim sugested trying 750W (77.5V) per 8 ohm driver
This is 3dB less than full power.
As your amp has -10dB indicator lights limit down to that level and then add another 6 or 7db - Then check the speaker excursion. Not very scientific I know but should put you roughly at the correct level, regardless of how you have set your amplifier up
Thanks For your input Jim. I guess I just dont understand if it is the lack of compression or to much compression in this area that contributed to the damage of my speakers.
I left the tapper out of my boxes for experimentation and would like to hear the pros and cons of a tapper in the L12 area even if it does not directly effect the cone ripping problum.
Thanks Andy
Thanks for your input Xoc1; I have been finding the limiter settings seem to be more of an art than science. I have fould some formulas and calculators online that maybe helpfull but was wonduring if measuring the power to the speakers with some sort of inline watt meter would be the best.
Does this mean to limit the peaks to just 750 watts? and that normal program should be well under this.
How much would this change if I was running 2-8ohm drivers per channel?
Andy
Andy, your QSC PL380 seems to deliver;
8 Ohm per channel (1Khz, 1%THD) = 1400W
8 Ohm per channel (Dynamic) = 1800W
4 Ohm per channel (1Khz, 1%THD) = 2300W
4 Ohm per channel (Dynamic) = 3600W
2 Ohm per channel (1Khz, 1%THD) = 3000W
2 Ohm per channel (Dynamic) = 6000W
In 4 Ohm bridged = 6000W
In 4 Ohm bridged (dynamic) = 12000W
You can use 3 x SS15 cabs per channel or 6 cabs in bridged (every two cabs in series, and three of those series settings in parallel). In both ways you still have to use a limiter.
8 Ohm per channel (1Khz, 1%THD) = 1400W
8 Ohm per channel (Dynamic) = 1800W
4 Ohm per channel (1Khz, 1%THD) = 2300W
4 Ohm per channel (Dynamic) = 3600W
2 Ohm per channel (1Khz, 1%THD) = 3000W
2 Ohm per channel (Dynamic) = 6000W
In 4 Ohm bridged = 6000W
In 4 Ohm bridged (dynamic) = 12000W
You can use 3 x SS15 cabs per channel or 6 cabs in bridged (every two cabs in series, and three of those series settings in parallel). In both ways you still have to use a limiter.
Nothing wrong with the ultradrive meter.
As you can see in the manual for the DCX 0dB is +22dBu or 9.75V RMS.
Your amps gain is ether 26dB (19.953x) or 32dB (39.811x)
Using this useful calculator dB calculator for amplification (gain) and damping (loss) of an audio amplifier calculation decibel dB ratio - sengpielaudio Sengpiel Berlin you could work out the limiter setting you want.
For 77.5V and 26dB gain for the amp you want the input to the amp to be 3.88V RMS.
The change from 9.75V RMS (0dB for DCX) to 3.88V RMS is -7.994dB
So your limiter would be set at -7.994dB.
It's always a good idea to verify it working properly with a DMM, preferably with a lot lower setting.
As you can see in the manual for the DCX 0dB is +22dBu or 9.75V RMS.
Your amps gain is ether 26dB (19.953x) or 32dB (39.811x)
Using this useful calculator dB calculator for amplification (gain) and damping (loss) of an audio amplifier calculation decibel dB ratio - sengpielaudio Sengpiel Berlin you could work out the limiter setting you want.
For 77.5V and 26dB gain for the amp you want the input to the amp to be 3.88V RMS.
The change from 9.75V RMS (0dB for DCX) to 3.88V RMS is -7.994dB
So your limiter would be set at -7.994dB.
It's always a good idea to verify it working properly with a DMM, preferably with a lot lower setting.
Speakers don't come in perfect 2, 4 , 8 or 16 ohm configurations. So if you are going to use theory for calculating the 'ultimate' power loadings, start to measure the DC resistance as minimum load (the DC resistance is always a fraction lower). From there you can calculate the amounts of limiting you will need.
Because I do not what to do destructive testing I need to come up with a good theoretical number to set the limiters at so my subs will not get damaged again. I am thinking 750 watts is to high. Assuming 250 watts is my excursion limit for normal program materal, How high would I what to limit the peaks to prevent damage?
Andy
Andy
Hard to say how much power your speakers will take without damage now, as all your sub cones have been “tenderized” a bit.
Program music is a bad choice for setting limiters, as you never know exactly what is going to happen in regard to frequency and volume with the next cut on the CD the fireworks designer hands you, or how much of a LF transient a dropped microphone might have.
If I were in your position (seems like your system is somewhat unattended) I’d limit the speakers to Xmax, using pink noise, which contains all frequencies.
If that turns out to be only 250 watts ( I doubt it would be that low looking at the Hornresp sims showing Xmax for the SS15) then clamp the limiters down to 250 watts.
Looking at the cone excursion does not require any math to set the limiters to a safe excursion level, just a ruler and your eyeballs.
One thing more to consider, average power is usually what burns up speakers, if you mash hard into limiters, the speakers may see more average power than a more dynamic signal.
After setting the limiters, use the onset of limiting as a signal to turn down the level a bit, don't think that the limiter can save your speakers from every possibility of damage, unless set below the continuous rating of the speaker.
Art Welter
Andy, I have made the most HornResp from your cab based on Oliver's drawing. The minimum impedance is 5,3Ohm at 41Hz. Xmax will be reached with 56V. If you calculate the power from that it is 580Watt without the losses from power compression. The power compression is at least 3dB which means you will need at least 1160Watt to reach Xmax in reality. Since the driver is rated 900W max (EIA 426A), which is lower, I suggest 750W since it is 80%-85% of the EIA-426A max rating. Other people seem to use this figure with the 3015LF in TH's with higher compression ratio's so you will be save. Always use limiters and make sure the limiter led is not lighting the whole time.
qft. Of all the failures I've seen, only a couple have been visible failure. Most have been de-laminated voice coils from heat. I'd probably set my limiters some value around maximum peak power and just exercise caution with levels, I'd be inclined to think drivers will tell you audibly when they are operating outside of linearity.
I don't think limiters are meant to be perched on the threshold of damage so that you can ride the volume control as hard as you want for hours on end.
77.5V was a few posts up and 26dB gain came from the manual linked for your amp.
I usually use Hornresp for setting my limiter. So "worst case" won't cross ether limit.
If you want to factor in power compression and add a bit more it's up to you.
I just showed how to run the numbers. Picking the right one is up to someone else.
I usually use Hornresp for setting my limiter. So "worst case" won't cross ether limit.
If you want to factor in power compression and add a bit more it's up to you.
I just showed how to run the numbers. Picking the right one is up to someone else.
I always limit my ss15's to 500watts,
scott runs his fury subs up to about 700watts on occasion (typical 500watts) with the compression plate.
(3/4" baffle board the driver bolts to, and then 1/2" ply with the 10x6 opening in it)
I'm always playing it safe on the power numbers on my cabinets, and rarely get above 40v-56v typical, with 63v being my 'brick wall limit' value.
scott runs his fury subs up to about 700watts on occasion (typical 500watts) with the compression plate.
(3/4" baffle board the driver bolts to, and then 1/2" ply with the 10x6 opening in it)
I'm always playing it safe on the power numbers on my cabinets, and rarely get above 40v-56v typical, with 63v being my 'brick wall limit' value.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.