# Capacitor for Tweeter protection - Cheap or Higher Quality?



## edconline (Dec 18, 2014)

I am looking to order two capacitors to protect my tweeters from any turn on pop I may get when everything is done. This will be my first time running active so never needed to do this before. Using the MS8 as the processor, Tweeter will be crossed over at ~2KHz/24db. Tweeter is a Hertz ML 280.3. Fed from a JL HD900/5.

I'm looking at a 250V 100uF capacitor and wonder since this is purely for protection purposes and not going to be used as part of a crossover, should I go with come cheaper no-name ones or a better brand? Links: 

Cheaper ones

Better ones

From everything I have read, this should be an ideal size and voltage as well as type, just wondering what peoples thoughts are on quality. Thanks.


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## miniSQ (Aug 4, 2009)

why are you choosing 100uf? This one should work and is much cheaper

Amazon.com: Solen 30uF 400V Polypropylene Capacitor: Industrial & Scientific


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## edconline (Dec 18, 2014)

miniSQ said:


> why are you choosing 100uf? This one should work and is much cheaper
> 
> Amazon.com: Solen 30uF 400V Polypropylene Capacitor: Industrial & Scientific


I chose 100uF as everything I read said you want to be at least two octaves away from the actual crossover frequency you are running in order to minimize the chance that they capacitor's crossover will interfere at all. 100uF puts me just over 2 octaves from my crossover of 2KHz.


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## miniSQ (Aug 4, 2009)

then if you are going to be 2 octaves below, go cheap.


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## Alrojoca (Oct 5, 2012)

As long as it is a non polarized Polypropylene Cap it should be good, what you want to avoid is the aluminum electrolytic caps, you can get for under $2

Be prepared to have room for an aluminimum soda size can space when you are dealing with a 100uf cap.


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## evangojason (Feb 12, 2010)

Legatia: Tweeter Thermal Protection Device (For Active Systems) – Audio Intensity


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## edconline (Dec 18, 2014)

evangojason said:


> Legatia: Tweeter Thermal Protection Device (For Active Systems) – Audio Intensity



Those look cool, what is it though? As in how does it work? The price is certainly appealing I would just want to make sure it doesn't influence the sound/crossover point at all.




Alrojoca said:


> As long as it is a non polarized Polypropylene Cap it should be good, what you want to avoid is the aluminum electrolytic caps, you can get for under $2
> 
> 
> 
> Be prepared to have room for an aluminimum soda size can space when you are dealing with a 100uf cap.



It is that big?!?




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## Carlton8000 (Feb 5, 2011)

I am using a pair of Solen 27uf Caps from Parts Express on my Peavey ribbons.


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## Alrojoca (Oct 5, 2012)

edconline said:


> It is that big?!?
> 
> 
> Sent from my iPhone using Tapatalk


A 20uf 250 cap is 2.2" by 1" diameter. If you multiply that by 5, think of the size perhaps even bigger than a soda can.

If you can find a 75-150V the size may be reduced by over half of the projected size mentioned. 250V is overkill but lower V caps are not available or easy to find.

I'm curious about those HAT things, pictures can be deceiving since those look like tooth picks


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## SO20thCentury (Sep 18, 2014)

Where exactly is the best place to install these? I didn't realize they were that big when I'd planned to put it on the speaker out @ the amp.


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## SO20thCentury (Sep 18, 2014)

Alrojoca said:


> I'm curious about those HAT things, pictures can be deceiving since those look like tooth picks


me2


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## trumpet (Nov 14, 2010)

I'm not using capacitors for protection on my tweeters now since they're wired through passive crossovers. In the past I was using capacitors very similar to these: 22uF 100V Electrolytic Non-Polarized Crossover Capacitor


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## SO20thCentury (Sep 18, 2014)

That was more like I'd had in mind cuz I've got an assortment of them but on a thread last week somebody said the polypropylene was better ...don't zackly remember why...


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## miniSQ (Aug 4, 2009)

edconline said:


> It is that big?!?
> 
> 
> 
> ...


no...its like 3" long and maybe 1 3/4 deep.


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## thehatedguy (May 4, 2007)

The thermal thing seems more like a thermistor...which won't block DC.

FWIW, Parts Express has 4 different 100uf caps, and the prices are cheaper than what is listed on eBay for the same thing.

But Solen may end up being the cheapest if you buy straight from them since there will be no duties. Solen has their house brand and also Dayton from PE. The 100uf Dayton is $32.42 CAD vs $29.81 from PE here in the states.


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## edconline (Dec 18, 2014)

thehatedguy said:


> The thermal thing seems more like a thermistor...which won't block DC.
> 
> FWIW, Parts Express has 4 different 100uf caps, and the prices are cheaper than what is listed on eBay for the same thing.
> 
> But Solen may end up being the cheapest if you buy straight from them since there will be no duties. Solen has their house brand and also Dayton from PE. The 100uf Dayton is $32.42 CAD vs $29.81 from PE here in the states.



Thanks for the info! I'll stick with the capacitor, may as well have the protection from DC as well. I see Solen has an 82uF one I can order from Quebec. That will still give me two octaves of seperation. Two of those shipped to my door is $75. Probably as cheap as it's gonna happen. Especially considering $5 USD is like $100 CAD these days :mean:

Now hiding these damn things is gonna be another story, they definitely won't be able to go right next to the crossover. I don't see any issue putting them closer to the amp side right? As long as they are inline on one of the wires they should do what I need them to as I understand it. That way I can stash them in the trunk.


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## thehatedguy (May 4, 2007)

Would be AOK to put them next to the amp.


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## edconline (Dec 18, 2014)

thehatedguy said:


> Would be AOK to put them next to the amp.


Excellent, thank you!


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## evangojason (Feb 12, 2010)

This is the info I received on the HAT thermal protection device. "The hybrid device is a PTC thermistors can be used as current-limiting devices for circuit protection, as replacements for fuses. Current through the device causes a small amount of resistive heating. If the current is large enough to generate more heat than the device can lose to its surroundings, the device heats up, causing its resistance to increase, and therefore causing even more heating. This creates a self-reinforcing effect that drives the resistance upwards, reducing the current and voltage available to the device."


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## Alrojoca (Oct 5, 2012)

Interesting, I knew thermistors, can be used to regulate temperature, to keep heat in a device from overheating and turning on a heating device if the heat temperature is reduced below a certain range, almost like a thermostat.

Basically like a switch, usually in connection with another electronic controller board that will turn either a lamp or heating element, the thermistor regulates the heat by telling the controller board when to turn on or off the device providing heat, usually there is a thermal fuse in that circuit that will blow if the temperature exceeds a range for an extended period of time, the thermistor hardly ever blows.

No clue how it will work connected to a tweeter lead, I am not aware of other uses this component has besides the one mentioned, based on a bit experience working with them in certain heating parts of some devices. I would think if it gets heated above some temperature, will just block the signal, chances are once its triggered, you may have to buy another set, like if it was a fuse.


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## ATOMICTECH62 (Jan 24, 2009)

A cap chosen for one octave will be down 1 db at the crossover frequency and .5db for a cap at 2 octaves.
I doubt its even going to make an audible difference ether way.I dont even bother calculating it any more.I just grab anything from27uf-47uf to use,whatever I have laying around.The electronic crossover frequency and slope will make all the difference.I use 80uf on my 2"midrange domes.
A 80uf would be 2 octaves for 2khz with a 4 ohm tweeter and 40uf if its 8 ohm.If too large of a cap is used then there will be very little if any protection from a large DC spike.
The PTC type are more for thermal (power) protection and can pass DC.And,if you have an amp over about 30watts per channel the PTC will kick in under loud passages shutting the tweeter off right in the middle of a good jam session.Putting a resister in parallel with them will only attenuate the tweeter a few DB but it is still audible.Light bulbs in series with tweeters is the better choice for power(not dc)protection since they only cause compression which is not as noticeable as the PTC's when they cut out.


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## edconline (Dec 18, 2014)

Thank you for the more detailed description! It's really the turn on pops I'm concerned with more than anything as I've experienced them in previous systems. I'm sure the 80uF is overkill but I do want to keep it pretty far from the actual crossover. Keeping it a ways away also eliminates any phase shift the capacitor may introduce does it not?


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## cajunner (Apr 13, 2007)

Audio Note


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## edconline (Dec 18, 2014)

cajunner said:


> Audio Note


That is a cool read. I don't think I need anything that serious though, in theory the capacitor I am using shouldn't have any influence at all over the sound I am hearing.


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## beatswork (Oct 3, 2015)

Old thread but posting if it helps anyone. You can find 100UF 250v non-polar polypropylene caps on Ebay for as little as $3 each as motor starters. Looking at available specs I don't see any obvious (to me at least) reason why these would not perform the same as the "Audio" caps for DC blocking. Shout out if you do 

Search for:  100MFD 100uF 250V AC Motor Starting Capacitor


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## 14642 (May 19, 2008)

There is absolutely no need whatsoever to spend extra on a polypropylene cap for protection outside the passband. At high frequencies, the cap has no effect. 

Don't believe the hype.


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## 14642 (May 19, 2008)

The Audio Note written by Martin Colloms has absolutely no bearing here. none. Not the same circuit. 

None.


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## beatswork (Oct 3, 2015)

Andy Wehmeyer said:


> There is absolutely no need whatsoever to spend extra on a polypropylene cap for protection outside the passband. At high frequencies, the cap has no effect.
> 
> Don't believe the hype.


At $6 a pair including shipping I figured it was worth a bit of experimenting 

If there is a reasonably straightforward (and meaningful) way to test and log with RMS digital multimeter I'd be happy to post results.


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## sqshoestring (Jun 19, 2007)

Even expensive speakers come with fairly small caps for a reason. The light bulb thing is cool some used them, a bulb will be more resistant at higher current but I don't know how you size the bulb lol.

I always use a cap on a tweeter period. If your amp blows or a wire gets shorted it can toast any tweeter with no protection. Though I don't bother running active tweets anymore when I can passive them well enough I really rather not have the extra equipment, or save it to use on midbass.


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## beatswork (Oct 3, 2015)

sqshoestring said:


> Even expensive speakers come with fairly small caps for a reason. The light bulb thing is cool some used them, a bulb will be more resistant at higher current but I don't know how you size the bulb lol.
> 
> I always use a cap on a tweeter period. If your amp blows or a wire gets shorted it can toast any tweeter with no protection. Though I don't bother running active tweets anymore when I can passive them well enough I really rather not have the extra equipment, or save it to use on midbass.


Don't disagree I just wanted to experiment with active tri-amping and was afraid to run tweets naked. You can use fuses, bulbs, capacitors, poly switches all the way up through a fancy circuit with rectified diodes - in the last case I have no idea why you wouldn't just use a crossover and be done with it - but at any rate after reading far too many posts it seemed that a non-polypropylene cap around 100uf offered best protection vs. likelihood to cause non-linearity, distortion or other artifacts with crossing over mid region. YMMV


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## sqshoestring (Jun 19, 2007)

I usually ran a cap under my tweet xover so it had no effect really, but if the amp or wiring was messed up it would. Sometimes the cap was right at the xover I liked best and it seemed to work fine, though the cap is only 6db slope iirc so you don't want it too low. Certainly you can find more detail digging around here but I never noticed any ill effects. I used to cut open the xover on better tweets and buy the same value caps.


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## Alrojoca (Oct 5, 2012)

Then, why not TRUCONNEX Bass Blockers Set of 4 TCBB133-14 - Best Buy

A set for mids and set for the tweeters 


Assuming they are rated at least 30 volts each.


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## beatswork (Oct 3, 2015)

Alrojoca said:


> Then, why not TRUCONNEX Bass Blockers
> 
> A set for mids and set for the tweeters
> 
> ...


99% positive those are just generic electrolytic capacitors with some wire and shrink wrap. May work fine just saying the caps themselves would probably cost less than a $1 apiece for DIY. The point of 100uf for active setup is that they will filter approximately 2 octaves below where active crossover will be and thus only providing DC protection but no effect on crossover point.

Problem I ran in to with active setup was hiss from tweeters due to high sensitivity. L-pads would be handy but I have plenty of resistors on hand so just experimenting with what gives lowest noise floor while still allowing volume to be matched with other speakers.


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## Alrojoca (Oct 5, 2012)

It's just a convenience pack and my price would be just over $3, or maybe amazon

I have some stinger caps I will be using 

No clue if they are just a pretty plastic barrel covering some cheap electrolytic caps. I would use polypropylene not for sq, more for durability and reliability

I also found myself experiencing more silibance and SSS etc, with active pass and that was reduced changing the placement, you don't want them pointing at your face, also increase the slope to -24 db or 36db and that should reduce the hiss, and Eq if that does not fix it. Time to get a different tweeter.


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## bbfoto (Aug 28, 2005)

I think that the Bass Blockers are rated for 50 watts RMS IIRC and the XO Frequency specs listed are for 4-ohm speakers and of course provide a simple 6dB/octave roll-off. And yeah, they have to be just cheap electrolytics. The model #127BB800A2 is said to be an 800Hz XO @ 4-Ohms (so 1,600Hz @ 2-Ohm & 400Hz @ 8-Ohm). I'd also opt for better caps just for longevity, but yeah, no need for Black Gate or other "high-end" caps. 

Side note: I remember npdang providing Solen 27mfd poly "protection" caps when he sold the LCY Ribbons.


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## Alrojoca (Oct 5, 2012)

It would be interesting to open one and see what's inside
50w would not be an issue for tweeters, I think , it's just insurance.

Less work dealing with heat shrink or finding space to place a 250v cap as big as a prescription medicine orange container


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