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Multi-Way Conventional loudspeakers with crossovers

Driver ratings and protections
Driver ratings and protections
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Old 13th July 2004, 03:30 AM   #1
jackmcdowell is offline jackmcdowell  Argentina
diyAudio Member
Join Date: Jun 2004
Location: Argentina
Default Driver ratings and protections

Hi everyone! I finally got my speakers (I'll get them on thursday, they've been ordered though) but the rated watts are way below the amp level on my mid high drivers and my 10" drivers.
The setup is as follows:

15" horn loaded woofer at 8 Ohms, 200Wrms SPL +-95? (I remember it was pretty high)
10" horn loaded woofer at 8Ohms, 160W NOT RMS (just what it says on the back, so probably 80Wrms) and no idea about the spl.
1" titanium driver Selenium 210 ti 8Ohms 80Wrms @ 12db octave xover at 2000, or 60W at 12db octave at 1500
and some piezzos but that is just a resistance in series...

So my question is, my amp delivers some 200Wrms unclipped. I get the 12db crossover... BUT, I'll probably burn everything but the 15" and the piezos right?
So tell me what should I use?
Also the 1" drivers require the xover, but if for example I were to add a resistance in series to lower the current to it, wouldnt this mess up the xover since they are made to work for a specific resistance?

Please I would apreciate your thoughts, I Have searched the web for the answers for about a week now and have found no satisfying answers.
I've read about bulbs in series, polyswitches and their bulbs in parallel, resisters, so please help. These drivers are pretty expensive to me and I can't really afford to go blowing them up.

Thanks! Jack
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Old 13th July 2004, 11:08 AM   #2
hunter audio is offline hunter audio  India
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Join Date: Dec 2003
Location: Mumbai

depending upon approach there are quite a few ways for you to totally protect all your drivers and yet blast them all you like

first - jbl way (my openion the simplest and best)

take - 2 nos 220 micro farad capacitors 60 V and above (higher the v rating the better) series them in this fashion =

solder the +ve terminals together (the caps should be high quality - not chinese)

then connect them in series with the ten inch driver -ve terminal / this will c/o the diver above 80 - 100 ish and protect it

in addition you can - connect a motor cycle 40 watt head lamp in parallel to the ten inch (head lamp not halogen type) - when purchasing the headlamp check if it is beow 1 ohm anything below 1 ohm will work well

i recommend connecting the lamp only if you feel the ten inch is heating - the practical way is blast your drivers all connected and feel the heat of the voice coil directly at the centre of the back plate - if you find it heating up - then attach the bulb

in effect what will happen is - when there is a vc temp rise the resistance (or reactance what ever you like ) will increase this will inturn direct residue current to be dessipated trough the bulb - therefore in normal levels when the driver vc is not heated the buld will have hradly an effect

now for the selenium - are they magnet fluid cooled - if not cross over a bit higher than 2000

take the supply of the tweeters from the ten inch driver terminals points - that is after the 220 micro farad caps - if you want to be ultra careful

for the selenium after the capacitor of the 12 db net work connect a 20 watt bulb in parallel same as above

if you find the tweeter a bit forward connect a 10 ohm 5 to 10 watt fusable (high quality) resister in series - this will take care of spl matching and further protect the tweeter

for the piezos connect a 100 to 120 ohm 5 watt fusable resister in series (you can go up further on the ohms for level matching) - that will protect them well

happy enjoying - and blasting


transducer design engineer
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Old 13th July 2004, 11:56 AM   #3
BillFitzmaurice is offline BillFitzmaurice  United States
Join Date: May 2004
Location: New Hampshire
First, too much amp power is not a problem; too little is. The usual rule of thumb is to have at least twice the amp power as the speaker rating. Most drivers are blown due to power compression effects.

In a home setting chances of blowing things is small; you just shouldn't be playing that loud. But if you're using your system in a pro-sound environment you should have a compressor/limiter to eliminate the possibilitiy of blowing components. You also should be using multiple amps in a bi-amp or tri-amp configuration, and that means an active crossover that gives better protection to HF drivers. The best solution is a LMS like a Behringer DCX2496 or DBX DriveRack PA that does it all.
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Old 13th July 2004, 12:47 PM   #4
jackmcdowell is offline jackmcdowell  Argentina
diyAudio Member
Join Date: Jun 2004
Location: Argentina
Thank you hunter audio ! I'm going to have a chat with the guy designing my amp on thursday. It sounds like a good aproach, and that way I can be extra safe. I guess this is the best way because from what I understand polyswitches can be to slow.
What I was worried about and had never heard an answer for was if the resister would have an effect on the crossover, but I guess not.

And BillFitzmaurice, you're right, I have a triamp setup in my head, but for that I need another amp and an active crossover, both of wich I can't afford right now, although I do plan on doing this some day.

Thank you for your posts, Jack
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Old 14th July 2004, 10:08 AM   #5
hunter audio is offline hunter audio  India
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Join Date: Dec 2003
Location: Mumbai

the resistors will not have a effect on frequency - they are mostly there for spl matching - of each driver

in piezos resistors upto 120 ohms are for protection and tend to have no effect at all , in spl output too , to limit spl u will have to go higher

in my openion selenium titaniums are as goos as any - the titanium is light and thin how it should be - with a large dome profile

with this u can for go the piezos / totally a personal decision though

dont worry about using the bulbs - most comercial manufactureres uses them like jbl (though jbl wisely )

but bose seems to have bulbs all over the place plus ntc s all over the place -


transducer design engineer
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