Speaker Protection Schematic?

samsagaz · 17th November 2010, 06:19 PM

Hi guys can someone please point me to some schematic of some cheap speaker protection design? i want to add one to each of my speakers.

Exist some IC that help me to that?

THanks in advance

bob91343 · 17th November 2010, 07:30 PM

I suggest nothing more complex than a fuse.

Yes you can build an elaborate circuit that will use a relay to protect the speakers. If you must do it that way, look at some amplifier diagrams and you will find many circuits. Some simply cut off the speakers if the dc level exceeds some small amount, others actually monitor the signal and protect from large signals. None of these circuits is especially simple, and none as effective as a fuse.

What size fuse? Well figure the speaker impedance and decide how much current is too much. A regular fast blow fuse will pass rated current for an indefinite period but will open with larger currents, say 10-20% above rating. The higher the current, the faster the fuse blows, perfect for speaker protection.

Slipstreem · 17th November 2010, 07:42 PM

Agreed, and I'd be inclined to place the fuse inside the amplifier's negative feedback loop so that any change in the fuse's resistance with changing output current would be corrected for.

samsagaz · 17th November 2010, 07:59 PM

fuse will not lower the signal quality?

Slipstreem · 17th November 2010, 08:59 PM

If it's inside the amplifier's negative feedback loop, no. If it's outside it, just maybe at high output power levels.

Atilla · 17th November 2010, 09:01 PM

Fuses are a very questionable form of protection. If something messes up and your speaker sees full-rail DC across it, it'll literally blow up faster than your fuse can say "whoops". Also, picking the right rating for them is tricky - too low and they'll blow up for no reason, too high and they'll never save you.. If you want good protection, you'll have to do better than fuses.

As for sound quality, it's not the best thing to have in the signal path. It'll raise THD at low frequencies. But it's doubtful if it can introduce any audible changes, we're talking about distortion levels waaay down.

Get a nice, cheap, ready-made board from ebay, if you don't want to bother and you're done. Test it before you install it, just to be sure. I'm using quite a few different ones and apparently - it's hard to get them wrong

Minion · 17th November 2010, 11:18 PM

This IC will protect your speakers from DC

http://www.datasheetcatalog.org/data...ec/UPC1237.pdf

Redshift187 · 18th November 2010, 01:48 AM

I bought a kit off ebay for $13.50 and it has saved my speakers a few times. Just search for speaker protection and you'll find a few.

17th November 2010, 06:19 PM	#1
samsagaz diyAudio Member Join Date: Aug 2004 Location: Argentina	Speaker Protection Schematic? Hi guys can someone please point me to some schematic of some cheap speaker protection design? i want to add one to each of my speakers. Exist some IC that help me to that? THanks in advance

18th November 2010, 01:48 AM	#8
Redshift187 diyAudio Member Join Date: Aug 2008	I bought a kit off ebay for $13.50 and it has saved my speakers a few times. Just search for speaker protection and you'll find a few. __________________ Tyler

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17th November 2010, 07:30 PM	#2
bob91343 diyAudio Member Join Date: Mar 2010	I suggest nothing more complex than a fuse. Yes you can build an elaborate circuit that will use a relay to protect the speakers. If you must do it that way, look at some amplifier diagrams and you will find many circuits. Some simply cut off the speakers if the dc level exceeds some small amount, others actually monitor the signal and protect from large signals. None of these circuits is especially simple, and none as effective as a fuse. What size fuse? Well figure the speaker impedance and decide how much current is too much. A regular fast blow fuse will pass rated current for an indefinite period but will open with larger currents, say 10-20% above rating. The higher the current, the faster the fuse blows, perfect for speaker protection.

17th November 2010, 07:42 PM	#3
Slipstreem diyAudio Member Join Date: Oct 2010 Location: UK	Agreed, and I'd be inclined to place the fuse inside the amplifier's negative feedback loop so that any change in the fuse's resistance with changing output current would be corrected for.

17th November 2010, 07:59 PM	#4
samsagaz diyAudio Member Join Date: Aug 2004 Location: Argentina	fuse will not lower the signal quality?

17th November 2010, 08:59 PM	#5
Slipstreem diyAudio Member Join Date: Oct 2010 Location: UK	If it's inside the amplifier's negative feedback loop, no. If it's outside it, just maybe at high output power levels.

17th November 2010, 09:01 PM	#6
Atilla Soldering Gun Fanatic diyAudio Member Join Date: Jul 2008	Fuses are a very questionable form of protection. If something messes up and your speaker sees full-rail DC across it, it'll literally blow up faster than your fuse can say "whoops". Also, picking the right rating for them is tricky - too low and they'll blow up for no reason, too high and they'll never save you.. If you want good protection, you'll have to do better than fuses. As for sound quality, it's not the best thing to have in the signal path. It'll raise THD at low frequencies. But it's doubtful if it can introduce any audible changes, we're talking about distortion levels waaay down. Get a nice, cheap, ready-made board from ebay, if you don't want to bother and you're done. Test it before you install it, just to be sure. I'm using quite a few different ones and apparently - it's hard to get them wrong

17th November 2010, 11:18 PM	#7
Minion diyAudio Member Join Date: May 2006	This IC will protect your speakers from DC http://www.datasheetcatalog.org/data...ec/UPC1237.pdf

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