Capacitor Protection fro 808-8a Horn

[taudo]

Having asked this question myself, I'll pass on the answers I got:

1) Don't use any - good amps shouldn't "go DC" on you.

2) Use a cap value calculated for a 12 dB/octave crossover at a frequency 1/2 the real crossover frequency (e.g, 400 Hz if you're crossing over at 800 Hz). There are a number of "crossover calculators" online that will give you the value you want.

Sonically, my ears could not hear any _major_ degradation when I tried putting caps inline with tweeters. However, my ears have been exposed to far too many explosions and too much gunfire to be trustworthy!

It will be interesting to see what others have to say.

taudo

[Todd W. White]

Personally, I don't like them, unless they are part of a properly designed crossover network - when placed across the leads all by themselves, they make the HF sound funny to me...

Also, if you don't use really good ones of the right type, the sound can get really raunchy as the capacitors age...

[Fitts]

Hi,

I prefer to protect my horns with 1/4 amp fast acting fuses rather than any capacitor. I have blown a few fuses with the volume cranked up but never lost a diaphram yet. Don't use the slo-blow kind of fuse they can fry a voice coil before they give way.

Regards,

[HiFiPlayer]

I suggest use L-Pad (4pcs of 1/2W hi quality metal film resisters parallel, total 2W as 1 resister) to instead your capacitors protection idea. Cause hi frequency extension will be better than original. In home use, 1 to 2W resister is enough.

To the capacitor, use a same value?s Solen capacitor plus a 0.01uf Rel-Cap RT grade capacitor bypass (must Match) to replace the original one can provide more hi-fi and lovely sound.

As Taudo said, "good amps shouldn't "go DC" on you
Anyway, properly use your amps is the best way to protect your drivers.

[scootertrs]

Hi
how exactly do I protect my 808-8a drivers with capacitors and what type and size capacitor am I to use to protect my 808-8a drivers from dc pulses... how much will they affect the sound? The horns are being driven by a tube Peavey 60/60 amp... they are also protected by fuses

thanks

[scootertrs]

Well, I believed, maybe erroneously, that a capacitor when used for protection is put in series with the speaker, not accross... I guess a/c will jump accross the cap, but would look like an open circuit to a d/c voltage... any ideas?

I also think (and this is when I get in trouble) that tube amps require output transformers, so if that is the case, it would be a technical impossibility to get DC to the speakers from the Peavey 60/60. Yes? No? Maybe? Depending on the design?

As an aside... while we set up our equipment for a gig, the first thing we fire up are the 511b horns... by themselves... and play a Canned Heat CD... when "I'm going up the country" plays it sounds exactly as it did 30+ years ago in Woodstock while the roadies were setting up the stacks... you know they were using Altecs... talk about Deja vu

Thanks

[cclark65]

I have used them in series in the past, and that's how they are in the crossover. However, depending on the crossover, I think you can have other ones in parallel across the leads. I believe it has something to do with the crossover slope being 6 or 12, or even 18db. Just depends on the design of the crossover.

[thinking]

I was discussing the subject of speaker protection with Bill at Great Plains Audio a while back, about some of the floor monitors that Altec built at the end that had circuit breakers inside the cabinet. He told me that you can't simply do the math on what the speaker should be able to handle based on the numbers, that the value of the circuit breaker came out wrong. They determined what size to use by experimentation. Unfortunately most of us can't afford to blow things out to determine the correct value, so starting small (either a circuit breaker or a fuse) and working up to a value that will carry the load is the way to go. He also suggested a good quality compressor limiter in the circuit. (In this case, live sound reinforcement, and trying to keep the idiots from reving it till something blew.) It won't protect from a amp going to DC, but it will limit some other problems, like volume to high when you hit play, someone drops a mic, shorts a cord, etc.