Speaker protection

[Dominick22]

I have been seeing alot lately about speaker protection and I do not have this in my LM4780 amp. Just wondering if this is a huge risk I am taking that I should remedy fast or not.

Also, Some of my speakers have built in protectors. Is this suffiecient or should I still be running pros on the amp itself??

Dominick

[Stocker]

How many amplifiers have you fried by shorting the terminals or overloading the output stage? If = >1, then you might consider protection. If = >5, seriously consider it.

I for one, don't think it worth the effort, especially for a chipamp as economical to replace/repair as the LM-series.

[Dominick22]

Well, I have fried one chip although I am not %100 sure why. So the speaker pro protects the chip??

I thought it protected the speaker?? Call me crazy!LOL
*not trying to be sarcastic-I am really trying to understand*

Dominick

[Peter Daniel]

My chip amps are constantly powered on and so far I didn't experience any problems (for last two, three years). However, one needs to be certain that the source equipment does not produce any DC offset.

Whenever I change something with the equipment, making mods to the amps, connecting new sources or change PS, I always disconnect speakers from the amp first, and before connecting them back measure the DC offset.

At one time I was experimenting with a preamp and that produced 24V DC at the speakers, but I acted quicly and it didn't damage anything. I got only once in trouble blowing two of my Triangle midwoofers ($250 ea.) but it happened with a different amp: the A75.

The drivers I'm presently using are quite expensive ($800pc and 1000Euro/pc) but I still chose not to use any protection. You can check one of the older threads dealing with a subject: Amplifier and speaker protection circuits

The chips are protected for output short and will not produce DC offset if one rail fails. So you don't really need a circuit to protect chips, if anything, you need something to protect the speakers.

[carlosfm]

Originally posted by Peter Daniel
The chips are protected for output short and will not produce DC offset if one rail fails.

Peter, they will produce DC offset if one rail fails.
Otherwise you wouldn't need an output cap when using single supply.

[davidsrsb]

Another thing never mentioned in the data sheets is what will happen if one of the supply rails goes open (likely with fuse protection) or short to ground.

[Peter Daniel]

Originally posted by carlosfm


Peter, they will produce DC offset if one rail fails.
Otherwise you wouldn't need an output cap when using single supply.

I checked it, and it does not produce offset. But you need a load connected, otherwise you will see the offset.

[Peter Daniel]

And least one other forum member tried it as well: http://www.diyaudio.com/forums/showt...803#post229803

[mastertech]

Dominick22 -
I have been seeing alot lately about speaker protection and I do not have this in my LM4780 amp. Just wondering if this is a huge risk I am taking that I should remedy fast or not.

Also, Some of my speakers have built in protectors. Is this suffiecient or should I still be running pros on the amp itself??

Dominick
-------------------------------------------------
those spks that have protection yes theyre protected

typical of spks protection is provided with polyswitches,fuses ...,etc

cheers

[Bazukaz]

Well , if we need to protect loadspeakers only , why not use a simple fuse ? It should blow much quicker than a loadspeaker , if current rating is chosen correctly...