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Author Topic: fusing horn drivers.  (Read 1175 times)

John Sabine

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fusing horn drivers.
« on: May 06, 2014, 12:54:52 pm »

I need some help from the gurus. I want to fuse or use a lightbulb to protect the hf drivers in my line array boxes.  a couple of years ago I hand an amp go dc on the outputs and kill 8 of the 16 hf drivers in my line array. once I got the drivers replaced I put a capacitor inline with the + lead to the hf drivers to block dc. since then I've never been completely satisfied with the sound of my hf and I think that the caps are causing issues.  this weekend I came across another guy who had the same problem an had installed fuses inline with his hf drivers using external fuse holders on his jbl srx's.
my questions are is this truly a viable option? would bulbs be better? be it fuses or bulbs what is the best solution for 2 16 ohm 50 watt drivers in parallel?


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Tim McCulloch

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Re: fusing horn drivers.
« Reply #1 on: May 06, 2014, 01:09:54 pm »

I need some help from the gurus. I want to fuse or use a lightbulb to protect the hf drivers in my line array boxes.  a couple of years ago I hand an amp go dc on the outputs and kill 8 of the 16 hf drivers in my line array. once I got the drivers replaced I put a capacitor inline with the + lead to the hf drivers to block dc. since then I've never been completely satisfied with the sound of my hf and I think that the caps are causing issues.  this weekend I came across another guy who had the same problem an had installed fuses inline with his hf drivers using external fuse holders on his jbl srx's.
my questions are is this truly a viable option? would bulbs be better? be it fuses or bulbs what is the best solution for 2 16 ohm 50 watt drivers in parallel?


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About 27 years ago I have fuses inline with my Renkus SSD1800 drivers.  Finding the right value was the challenge - either the fuses blew before things got loud enough or the VCs blew before the fuse.  The light bulb might be a better approach.

In my case I was wanting 2" exit driver performance from a 1" exit driver.  Your amp going DC means you need different amps (or find out why the amp's protection circuit failed to protect).  The other fellow you encountered has the same problem I had:  Not Enough Rig for the GigŪ.
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John Sabine

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Re: fusing horn drivers.
« Reply #2 on: May 06, 2014, 01:53:28 pm »

I wasn't very specific in my previous post the amplifier actually smoked all the horn drivers upon being switched on. i've never actually blown any horn drivers on this rig while running a job although in the spirit of full disclosure I did have a few diaphragm to go bad early on due to defective glue being Used. The voice coils would cleanly.separate from the diaphragms resulting in lots of rattling.


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Richard Turner

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Re: fusing horn drivers.
« Reply #3 on: May 06, 2014, 04:18:03 pm »

I need some help from the gurus. I want to fuse or use a lightbulb to protect the hf drivers in my line array boxes.  a couple of years ago I hand an amp go dc on the outputs and kill 8 of the 16 hf drivers in my line array. once I got the drivers replaced I put a capacitor inline with the + lead to the hf drivers to block dc. since then I've never been completely satisfied with the sound of my hf and I think that the caps are causing issues.  this weekend I came across another guy who had the same problem an had installed fuses inline with his hf drivers using external fuse holders on his jbl srx's.
my questions are is this truly a viable option? would bulbs be better? be it fuses or bulbs what is the best solution for 2 16 ohm 50 watt drivers in parallel?


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Yorkville used part # 3652 on the ef508, and possibly some of the older tx2/4/5/8

by specs it is a phillips 13620 R2 Duplo-d 24v 55/50w bulb. these are used on the high freq circut in series with the HF driver which is a 2" exit B&C compression. just the high beam circut of the bulb is used but the low beam will work in a pinch till it can be replaced.

any time I went looking Yorkville was the cheapest and fastest source for them as its a not common anymore auto bulb.


On smaller 1" horns the usual suspect was an 1156LL standard tail light bulb.
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Jens Droessler

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Re: fusing horn drivers.
« Reply #4 on: May 06, 2014, 06:07:55 pm »

A fuse would be a viable way. Leave that cap in and put the fuse in parallel to the cap. So if the fuse blows, you will still have highs, just not as nice as before. The problem with the caps alone is that the settings in your processor would need a modification to include the difference in phase and response the cap adds.

A bulb OTOH wouldn't be such a good idea. They change their resistance heavily with the current flowing through them. Worst case you get pumping in the highs. Best case you get don't get enough highs out of your boxes when driving them hard, so the tonal balance tilts. Surely both aren't desirable for you.
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John Sabine

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Re: fusing horn drivers.
« Reply #5 on: May 06, 2014, 10:15:56 pm »

wow.  that's either crazy, genius, or crazy genius! :)


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Matthew Knischewsky

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Re: fusing horn drivers.
« Reply #6 on: May 07, 2014, 10:27:28 am »

Hi John,

What value capacitors did you use for protection? Usually you'd pick a value that would be considered very low for a crossover point but would be sufficiently out of band in normal operation while still offering DC protection. Also helps if there's a mis-patch or wrong processor setting used, the idea is hopefully someone would notice it's wrong before running the rig all the way up.

As has been stated, finding the "right" value for a fuse is usually trial and error.

Using a light bulb... that's a compromise too and if you are having sound quality issues with capacitors I think using a bulb is going down a similar path. That said, if I was to try a bulb the 1156 recommended by Richard would be my starting place for 50 watt drivers.

Bypassing the cap with a fuse is a good idea but one possible downside is you might not know the fuse is blown unless you inspect every fuse in the array. Yes the drivers continue to operate but with different response curves.

As always in audio...everything is a compromise.

Matt
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Joseph D. Macry

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Re: fusing horn drivers.
« Reply #7 on: May 07, 2014, 10:32:58 am »

I wasn't very specific in my previous post the amplifier actually smoked all the horn drivers upon being switched on. i've never actually blown any horn drivers on this rig while running a job although in the spirit of full disclosure I did have a few diaphragm to go bad early on due to defective glue being Used. The voice coils would cleanly.separate from the diaphragms resulting in lots of rattling.

I had a similar problem with some Community R.5's at a baseball field, powered by a QSC CX902 amp. The speaker lines have Edco lightning protection blocks in series, meant to open like a fuse if the voltage exceeds (in this case) 43 volts. Remarkably, the amp would smoke these protectors upon being turned OFF. A quick check with the multimeter showed the amp was delivering a burst of 56 VDC upon turn off. I sent it back to QSC for repair.
My point? Your amp may need service if it is delivering such a burst of DC voltage.
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John Sabine

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Re: fusing horn drivers.
« Reply #8 on: May 07, 2014, 12:00:49 pm »

the offending amp was repaired and immediately sold.


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David Allred

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Re: fusing horn drivers.
« Reply #9 on: May 07, 2014, 01:09:01 pm »

If you go the fuse route... use a slow-blo at the cont rating in-line with a fast-blo at the peak rating.
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