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Electronic crossover and tweeter protection?


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Greetings, are those of you that use only electronic crossovers with multi amp setups using any passive tweeter protection? I am wondering if I should put a simple first order cap in the path after my amp to protect my tweeters or boldly trust the electronic crossover prior to do all the tweeter protecting? Even amp thump will go straight to the tweeter if nothing in the path, but I also understand the desire of exactly that.

Bit scared to run it open.

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It should be fine, on first start up, keep levels low incase you have bass freq sending to tweeter by mistake. If it sounds well to each driver then slowly increased levels.

 

Make you understand what order crossover freq is being sent to the driver at its lower recommended limit. For example, send 1500hz and above to tweeters and have at least a 2nd or 3rd order crossover for 12 or 18dB cutoff instead of 1st 6dB only, unless tweeter is designed for it.

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Thanks AL.M

I decided to do my test running with a solitary cap outside the cabinet so I can discard it once confident I have nothing nasty going on. The crossover point of the cap is just below the electronic crossover point and that is rolling off at 3rd order so the cap should be transparent. It will be interesting to see what changes when I remove it. Phase should then be correct so I expect to hear some change.

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On 23/01/2021 at 8:53 PM, Onslo said:

Greetings, are those of you that use only electronic crossovers with multi amp setups using any passive tweeter protection? I am wondering if I should put a simple first order cap in the path after my amp to protect my tweeters or boldly trust the electronic crossover prior to do all the tweeter protecting? Even amp thump will go straight to the tweeter if nothing in the path, but I also understand the desire of exactly that.

Bit scared to run it open.

 

If you're unsure... then you should probably use protection.

 

The longer answer depends on the specific tweeter .... the gain in the system (very important consideration - as even if you keep signal levels low... lots of gain can still result in loud noises for pop or thumps, or whatever) .... and how likely thumps or pop, etc. are.

 

That being said, if you have a lot of gain (and are running low level) you should probably reconsider the gain structure the system as it will improve performance, often quite dramatically.

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On 23/01/2021 at 8:53 PM, Onslo said:

amp thump will go straight to the tweeter if nothing in the path

Bit scared to run it open.

 

Yes, you do need to have an amp which doesn't 'thump' on turn on and turn off.  :)

 

On 23/01/2021 at 8:53 PM, Onslo said:

Greetings, are those of you that use only electronic crossovers with multi amp setups using any passive tweeter protection?

 

I have been 3-way actively driving my Maggies for over 20 years - without a cap for protection - and have never blown a ribbon through an amp misbehaving.  But I have had a ribbon blow from a breeze through a nearby door.

 

If you decide to use a cap - it needs to be large enough value (given it's only a 6dB slope, to make the roll-off point at least 3 octaves (preferably 4) below the tweeter HP filter's roll-off point.

 

Andy

 

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2 hours ago, andyr said:

 

Yes, you do need to have an amp which doesn't 'thump' on turn on and turn off.  :)

 

...

 

If you decide to use a cap - it needs to be large enough value (given it's only a 6dB slope, to make the roll-off point at least 3 octaves (preferably 4) below the tweeter HP filter's roll-off point.

 

Andy

 

Great advice.

 

The other option for the high-pass passive is to include it in your calculation for the tweeter crossover. Then you can spend the extra you would have on the size (at 3-4 octaves below roll-off) on a better cap. After all, it'll always be in the signal path, and a 10uF cap is much cheaper than a 160uF cap (for the same quality).

 

One other thing which I was glad about (protection) when I was testing, was the crossover 'thump'. I was initially using Behringer pro stuff to test what I was looking for, and those buggers have an almighty thump if you have the amps already on.

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29 minutes ago, Cloth Ears said:

 

One other thing which I was glad about (protection) when I was testing, was the crossover 'thump'. I was initially using Behringer pro stuff to test what I was looking for, and those buggers have an almighty thump if you have the amps already on.

 

 

Yes, crossover thump can certainly be a problem.  I can't remember whether the Rod Elliott XOs I was using before the miniDSP had a thump ... or not.  The miniDSP doesn't.

 

29 minutes ago, Cloth Ears said:

 

The other option for the high-pass passive is to include it in your calculation for the tweeter crossover. Then you can spend the extra you would have on the size (at 3-4 octaves below roll-off) on a better cap. After all, it'll always be in the signal path, and a 10uF cap is much cheaper than a 160uF cap (for the same quality).

 

 

Not sure that a cap has to be quite that large, CE?  According to my old Box Hill TAFE 'Loudspeakers' course notes, 20uF is required for a 1kHz roll-off, for an 8 ohm driver.  If the tweeter roll-off was @4kHz - 4 octaves below is 250Hz, right?  So 20uF becomes 80uF.  But, yes - still large (and expensive) for 'boutique' caps.  :(  And that value doubles for a 4 ohm driver.

 

Andy

 

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1 minute ago, andyr said:

 

Yes, crossover thump can certainly be a problem.  I can't remember whether the Rod Elliott XOs I was using before the miniDSP had a thump ... or not.  The miniDSP doesn't.

 

 

Not sure that a cap has to be quite that large, CE?  According to my old Box Hill TAFE 'Loudspeakers' course notes, 20uF is required for a 1kHz roll-off, for an 8 ohm driver.  If the tweeter roll-off was @4kHz - 4 octaves below is 250Hz, right?  So 20uF becomes 80uF.  But, yes - still large (and expensive) for 'boutique' caps.  :(  And that value doubles for a 4 ohm driver.

 

Andy

 

Rod always used to have a relay based slow start kit (which I reckon was probably a must if your transformer is any size.

 

And I was using a 2kHz crossover @8ohm for my (theoretical) choice. I actually found to the difference between a 24dB/octave and a 30dB/octave crossover is barely discernible for a cloth ears like myself...

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