protecting my speakers from my GC

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damitamit

Member
Joined 2003
#1
After blowing up the crossover and drive unit on one of my Kef Q1s with (i think) my gainclone. well im sure it was my gainclone.

How do i protect my speakers from any other gc mishaps?

would just putting a fuse at the speaker terminals work? what sorta amperage?

btw, what couldve caused the speaker to blow. it was playin at low volume..

thanks
Amit
 
#5
Of course you must know what you want to protect the speakers
against: DC, oscillations or just too high power?

Which of these things do the Elliott and Velleman kits check?

Edit: OK, oscillations are mostly interesting to detect to protect
the amp, since a Zobel filter should do the job of protecting the
speakers.
 
#6
Christer said:
Of course you must know what you want to protect the speakers
against: DC, oscillations or just too high power?

Which of these things do the Elliott and Velleman kits check?

Edit: OK, oscillations are mostly interesting to detect to protect
the amp, since a Zobel filter should do the job of protecting the
speakers.
Click to expand...


i don't think he's trying to protect against high power either, since he said he's playing at low power

i'll guess its dc that blew it 🙂

as i suggested, check your dc offset .. make sure its low .. mine's at 28mV w/o any problems
 
#7
elizard said:
i don't think he's trying to protect against high power either, since he said he's playing at low power

i'll guess its dc that blew it 🙂
Click to expand...

Yes, it was hardly high power that blew it in this case. For some
people it might be useful with such protection, though. My
comment was merely a reaction to the fact that people often
speak about speaker protection, without specifying what kind
of protection they mean.

DC is a good guess but I suppose it could be oscillations too,
at least it there is no Zobel filter. Did the amp get hot??

BTW, one must not forget that statistically, things do occasionally
break without any obvious reason, which could depend on
manufacturing defects, fatigue etc. I blew a speaker once
for no apparent reason. I had used the same speakers and
amp for three or four years without problem, and I didn't play
particularly loud. I replaced the faulty element and it never
happened again.
 
#8
It must be DC he's talking about...

If you forget to connect (or it breaks later) Vin+ to ground you almost get clean rail voltage at your Vout and Vin- ! Happened to me once. (It's the inverting design I'm using.) I was sensible enough to meassure the creature before connecting it to anything, so no harm was done.
 
#9
If you forget to connect (or it breaks later) Vin+ to ground you almost get clean rail voltage at your Vout and Vin- ! Happened to me once. (It's the inverting design I'm using.) I was sensible enough to meassure the creature before connecting it to anything, so no harm was done.
Click to expand...

And that's only one way to get nasties on the output! The negative rail connection from my PSU to amp broke and that put 36VDC on my terminals. Like Thomas, I was lucky enough to have tested the amp before connecting the speakers!

I've been testing my GC's with old or cheap speakers so far but will revert to using my Velleman protection modules before connecting up my precious Goodmans 201's. :nod:
 
#10
When a load is connected and negative power is missing the protection circuit of the chip kicks-in pretty fast. I would expect most reasonably powerful speakers to be safe. It will be interesting to see how much the relays in your Velleman will affect the sound quality. If the relays i've tried in the past are similar - a lot.

cheers
peter
 
#12
damitamit said:
After blowing up the crossover and drive unit on one of my Kef Q1s with (i think) my gainclone. well im sure it was my gainclone.

How do i protect my speakers from any other gc mishaps?

would just putting a fuse at the speaker terminals work? what sorta amperage?

btw, what couldve caused the speaker to blow. it was playin at low volume..
Click to expand...

Have you checked what happened AFTER the fact?

Did you check DC offset and what did you get?

A fuse will not protect from DC, only from higher levels. Unfortunately the woofers are the ones to go when DC is present, because tweeters usually have a blocking cap.

What did you blow on your Kef? If it's the tweeter then you had oscillation or high level probably.

In any case I have not seen threads on this Forum that deal with the need to protect our speakers and still have a good sound.


Carlos
 
#13
thanks for the replys!

I havent infact checked the amp after the incident. I had to go away for a few weeks and now im back, looking at it again.

The woofer blew on the Kefs.

What do you mean by the DC offset? is it just the dc at the output terminals?


btw, i did test first with a crap speaker. The amp was running fine so connected up the Kefs. They were running fine for a hour or so until this happened...

thanks
Amit
 
#18
Sometimes, speakers just fail without cause, from use. Too loud, too much bass, for too long.
If you have a REAL National Semiconductor / TI Overture chip in your amp, it should protect very well from DC and shorts.
The fake chips that are around, do not have this. A real TI chip can be shorted while playing without consequence. If it blows, it was fake. If one supply voltage fails, it will shut down.
 
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