# Capacitors harming tweeter performance?



## jrodefeld (Dec 21, 2018)

After inadvertently blowing some tweeters when I went Active, I bought some capacitors and some better tweeters than the old ones I was using.

Here's what I'm currently running:

Pioneer DEH-80PRS
ScanSpeak Illuminator D3004/6020-00 tweeters
Focal Flax mid-woofers (came with the PS165F component set)
Morel Ultimo SC 124 12" subwoofer
Arc KS1200.1 mono amp
Arc XDi 850.5 5-channel amp


By all accounts, the Scan Speak tweeters should be a substantial upgrade from the Focal tweeters they are replacing. However, I haven't been overly impressed so far.

I'm wondering whether I bought the wrong capacitor or installed it wrong? I'm thinking maybe it's degrading or changing the sound of the tweeters in some way.

The capacitors I bought were: 22uF 100V Electrolytic Non-Polarized Crossover Capacitor

I got them from PartsExpress dot com

They are VERY cheap. I installed them on the + wires going to the tweeters right next to the amp.

According to what I've read, a 22uF capacitor should block all frequencies lower than 1807hz. This is pretty close to my crossover point of 2500.

I recently read that it's better to have a capacitor that's two octaves below the crossover point. In this case, that'd be around 600hz.

According to the AudioFrog tuning PDF, it says:

"In an active system in which your tweeters are driven by an amplifier directly, install a capacitor in series with each tweeter to protect it from erroneous crossover settings, turn on and turn off pops and other failures that may destroy them. Choose a capacitor value that provides a -3dB point about an octave below the tweeter’s Fs."

The ScanSpeak tweeters have a very low fs rating of 700hz. I'm not sure what value a -3db point an octive below 700hz would be, maybe someone could translate this for me?

Anyway, it looks like the capacitors I've chosen are not the right ones based on these recommendations.

What I'm most curious about though is whether they'd really degrade performance?


One final question I have is whether or not there is any difference in the method of setting the amplifier gain controls in an Active system? The gain controls on both the tweeter and mid-woofer channels are set pretty low as it is but I'm sure they're not really dialed in correctly.

Thanks for the help.


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## SkizeR (Apr 19, 2011)

get a 47uf or higher. That said, they dont effect performance to a noticable degree if the signal passing through is unaffected.


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## Sine Swept (Sep 3, 2010)

I found this chart

http://techtalk.parts-express.com/filedata/fetch?id=1134633


The thing I always wondered was if having the protection capacitor affects the 24 db slope I have set in my DSP. ie is my slope now 24 db + or - the capacitance added by the protection capacitor?


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## unix_usr (Dec 4, 2013)

68mf for a 4ohm driver yields approx 600hz, that said - read this post (much better than any other description I’ve ever come accross)

https://www.audiofrog.com/community...p-tweeters-in-systems-with-active-crossovers/


Sent from my iPhone using Tapatalk


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## maybebigfootisblurr (Nov 4, 2011)

How much running time do you have on them? I'm running inferior tweeters, but they are 1" textile domes and they definitely improved quite a bit after a month or so of playing.


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## Nirvana (Sep 18, 2009)

The high-pass, first order filter from the cap that close to your crossover will most likely be altering the phase at your crossover. Try a 3rd order crossover or change out the protection cap.


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## Holmz (Jul 12, 2017)

Can you put a picture or a sketch of how they are installed?


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## bassace (Oct 31, 2011)

In a capacitive circuit voltage lags the current. I wonder if this has any effect on tweeter performance? 

But there is also an inductive load at the tweeter. Buuuut furthermore, there is greater inductive load with the larger drivers. 

Where's that Patrick Bateman guy when you need him? :snacks:


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## GEM592 (Jun 19, 2015)

I really like Scanspeak mids. I have nothing whatsoever to say about their other stuff. I don't even want to comment on why they feel the need to have a full 4 ohm tweeter line. Whoever invented the 4 ohm tweeter needs counseling.


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## dcfis (Sep 9, 2016)

GEM592 said:


> I really like Scanspeak mids. I have nothing whatsoever to say about their other stuff. I don't even want to comment on why they feel the need to have a full 4 ohm tweeter line. Whoever invented the 4 ohm tweeter needs counseling.


DVC 2ohm ftw!


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## dcfis (Sep 9, 2016)

https://www.audiofrog.com/community...p-tweeters-in-systems-with-active-crossovers/


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## bluesman1 (Mar 2, 2010)

You'd want a cap to filter at least 1 octave below your active crossover point. It should be pretty well transparent there. You can go 2 octaves below but the lower you go the more low frequency energy is going to make it to the tweeter if there is a mishap with the active filter or a turn off or turn on "pop". I'm guessing that the reason why Audiofrog is suggesting using a protection capacitor at a crossover point that is 1 octave below the tweeters resonant frequency (FS) is because the tweeters impedance peaks at it's resonant frequency. But if you decide to calculate the protection cap value at 1 octave below an FS of 700 hz, that's 350 hz and, again, that allows for a good deal more energy to reach the tweeter in the event of transient pops or a failure or mistake with the active crossover. One octave below the 2500 hz active crossover frequency should be a safe point to calculate for the protection capacitors value in terms of both sonic transparency and protection. A 47uF cap should go to work at about 1 octave below your 2500 hz crossover point. If you're bound and determined to find a value 1 octave below the tweeters FS then 150uF should work. These values are roughly derived by looking at the response plot for impedance/frequency.

Those bi-polar caps are cheap enough. Buy a couple of each value to try.


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## Adrock (Jan 21, 2019)

The research I've done on this very topic has led to a one octave target. The starting crossover point rule of thumb is at least double the Fs, which should be 1400 Hz for those tweeters. You have selected 2500 Hz, so one octave would be 1250 Hz. This should put the cutoff outside of the 24 db slope enough as to not cause issues with phase shift and a cutoff to high in the 24 db slope. 

Also, the DC resistance of the tweeter should be used to calculate the capacitor rather than the nominal impedance rating of the tweeter, which is 4 ohms. The last post in the AF forum is where Andy mentions the use of DCR to calculate. 

Get your digital multimeter out and measure the DCR. Then calculate the cap using the DCR to get you close to the 1250Hz or go lower as you see fit. Or, go low enough to not affect anything if you want to change your crossover point to be lower than 2500 Hz in the future.


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## Eric Stevens (Dec 29, 2007)

capacitor quality will affect audio quality when used in series as a filter, no if's, and's or but's about it. 

If you think the capacitor is causing issues remove it from the system and test, it is only to protect when amplifers clip as that is post signal processing so full range/bandwidth.

I would suggest the highest quality non polar electrolytic you can afford at around 500 Hz with a high quality .1 or 1 uf poly bypass cap in parallel.


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## Chris12 (Sep 20, 2018)

Eric Stevens said:


> *capacitor quality will affect audio quality when used in series as a filter, no if's, and's or but's about it.*
> 
> If you think the capacitor is causing issues remove it from the system and test, it is only to protect when amplifers clip as that is post signal processing so full range/bandwidth.
> 
> I would suggest the highest quality non polar electrolytic you can afford at around 500 Hz with a high quality .1 or 1 uf poly bypass cap in parallel.


Wow. Andy directly contradicts this in the link provided above. His take on non-polar electrolytic capacitors is that the consumer should buy the cheapest available part that fits their needs.

But, I am also using 68uF caps on my tweeters (gs10’s), and they really don’t sound that good. Removing them (the caps) would be pretty involved, but you’ve very got me thinking..

Edit:

“*Finally, there are lots of different kinds of caps. Which one should you choose? Some people will tell you that you need one of those super-duper polypropylene caps and that you should NEVER use an electrolytic cap. For this application, that's hogwash. For this exercise, I've used an electrolytic cap. Below are pictures of the two caps that are available from Parts Express. The first is an electrolytic. It's costs about $1.75.



The second one is a polypropylene cap. It costs about $29.


Be sure to choose NON-POLAR caps. Those are the ones without the stripe and the (-).

Either one is fine for this application. Spending the additional $27.25 is, from a technical perspective, completely unnecessary. Get your car washed a couple of times instead or take your sweetie to a movie.”*


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## bluesman1 (Mar 2, 2010)

Aside from the "boutique" folks the consensus on the Parts Express bi-polar electrolytics is pretty good as far as bi-polar electrolytics go. 

For a more "upscale" bi-polar electrolytic, there aren't a ton of options. If someone really wants to go that route then look at:

-Nichicon Muse ES 
-Audio Note Kaisei (careful, they have both polarized and bi-polar) and maybe
- Jantzen Elko or Mundorf E-cap Mlytic (plain/smooth film versions). 

Personally I don't think a higher end cap makes much of a difference in this application nor do I think a bypass cap will make any difference. If you really want to bypass an E-cap here, go with a film bypass of at least 10% of the total capacitance. These are nothing more than my opinions.


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## Eric Stevens (Dec 29, 2007)

Chris12 said:


> Wow. Andy directly contradicts this in the link provided above. His take on non-polar electrolytic capacitors is that the consumer should buy the cheapest available part that fits their needs.
> 
> But, I am also using 68uF caps on my tweeters (gs10’s), and they really don’t sound that good. Removing them (the caps) would be pretty involved, but you’ve very got me thinking..
> 
> ...



I agree that a polypropylene film cap is overkill and un-necessary. But I dont think buying the cheapest available option is the correct approach either. A high quality non-polar electrolytic is not that expensive especially when compared to the cost of the other components in the system.


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## Eric Stevens (Dec 29, 2007)

Only reason in most systems to have the capacitor is to protect the tweeters from amplfier clipping. I personally would not put one in my system intended for SQ. If in a system that will see use as a portable rave system or the volume is always at 11 there is a case for adding a capacitor in series with the tweeter for protection.


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## Holmz (Jul 12, 2017)

Eric Stevens said:


> Only reason in most systems to have the capacitor is to protect the tweeters from amplfier clipping. I personally would not put one in my system intended for SQ. If in a system that will see use as a portable rave system or the volume is always at 11 there is a case for adding a capacitor in series with the tweeter for protection.


How does it protect from clipping?
The idea that amp would be clipping seems more probable in a passive system than in a active system.

In an active system the amp clipping for a tweeter would seem to happen seldomly if at all. And if it did clip on a tweeter spectrum, then how would that be much of a problem if it is in the 2 to 20 kHz range?


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## I800C0LLECT (Jan 26, 2009)

I had a bad RCA and zero caps on my active Tweeter. First time I ever blew one. That RCA popped and scared the hell out of me. Took me a couple days to realize that was the culprit. I was pissed.

Sent from my ONEPLUS A6013 using Tapatalk


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## GEM592 (Jun 19, 2015)

Holmz said:


> How does it protect from clipping?
> The idea that amp would be clipping seems more probable in a passive system than in a active system.
> 
> In an active system the amp clipping for a tweeter would seem to happen seldomly if at all. And if it did clip on a tweeter spectrum, then how would that be much of a problem if it is in the 2 to 20 kHz range?


+1

As I've said before, I don't think adding caps does much to protect against clipping. It mitigates it some, but damage can still be done and you are better off not clipping.


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## GEM592 (Jun 19, 2015)

dcfis said:


> DVC 2ohm ftw!


I admit I would want to hear them, but I would only have like 12 seconds to.


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## GreatLaBroski (Jan 20, 2018)

A 22uf cap on your D3004/6020-00's will act as an 1st order 1800hz butterworth crossover. This means you'll have a slope of -3db from 1800hz, about -1.5db at 3600hz, and so on up to above 30khz.

So yes, it can affect it. I'm not sure if that's what you're hearing though. What are your crossover points?


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## Holmz (Jul 12, 2017)

GEM592 said:


> +1
> 
> As I've said before, I don't think adding caps does much to protect against clipping. It mitigates it some, but damage can still be done and you are better off not clipping.


We are not even sure that there I should clipping, and even if if was, then how does a capacitor protect the tweeter?

One could pump a square wave into the tweeter and the coil should be moving if it is well above the minimum frequency. Or moving if it not maxing out.


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## Eric Stevens (Dec 29, 2007)

Holmz said:


> How does it protect from clipping?
> The idea that amp would be clipping seems more probable in a passive system than in a active system.
> 
> In an active system the amp clipping for a tweeter would seem to happen seldomly if at all. And if it did clip on a tweeter spectrum, then how would that be much of a problem if it is in the 2 to 20 kHz range?


When an amplifier clips it is not filtered as it is after any processing including filters on the input of the amplifier. The low frequency content of the clipped signal is what does the damage. The capacitor blocks the worst of the signal caused by the clipping that would damage the tweeter.

I agree this is not going to be a common occurence, but it does happen in the systems that spend a lot of time at full tilt or are used as portable rave system.

To be totally accurate we arent protecting from clipping we are protecting the tweeter from low frequency information that can happen when an amplfier is overdriven or has other problems like a DC offset for example.


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## Holmz (Jul 12, 2017)

Eric Stevens said:


> When an amplifier clips it is not filtered as it is after any processing including filters on the input of the amplifier. The low frequency content of the clipped signal is what does the damage. The capacitor blocks the worst of the signal caused by the clipping that would damage the tweeter.
> 
> I agree this is not going to be a common occurence, but it does happen in the systems that spend a lot of time at full tilt or are used as portable rave system.
> 
> To be totally accurate we arent protecting from clipping we are protecting the tweeter from low frequency information that can happen when an amplfier is overdriven or has other problems like a DC offset for example.


This seems 100% true, but the low frequency content would become a square wave at something over the crossover frequency. It is not exactly like DC going to the speaker.. it is higher frequency square waves.

There is really no low frequency information going to the tweeter in an active system.

Any turn-on popping, or miswiring the speakers are protected, but one should not really need a capacitor except for preventing rookie mistakes... and the amp spewing out DC, which is rare.
(But I used them anyhow)


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## evo9 (Jul 6, 2005)

jrodefeld said:


> After inadvertently blowing some tweeters when I went Active, I bought some capacitors and some better tweeters than the old ones I was using.
> 
> Here's what I'm currently running:
> 
> ...



I would use a 30uF capacitor

I recommend you go here https://www.the12volt.com/caraudio/passive-crossover-calculator.asp#ccc Input the tweeter information to get the correct value capacitor. Be sure to double the resonance frequency 

Or

https://youtu.be/hscMuzfyxQ4






.


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## BMW Alpina (Dec 5, 2012)

I just installed capacitor to protect my tweeter (Dynaudio Esotar 110) last week, I use Solen Capacitor and I did NOT hear any effect in SQ at all. The Solen Capacitor are reasonably price if you worry about an electrolytic capacitor effecting the SQ. They are large in size though..., but I am sure you could find a place to hide them if you want to.


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## JCsAudio (Jun 16, 2014)

I just used 22 uf to protect mine and went electrolyte because for just protection purposes it’s all you need. Works out to about 900 Hz at 4 ohms.


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## metako (May 19, 2012)

With a series cap the whole of your tweeter signal is going through the cheap cap. Its going to affect the sound quality. A quality polypropylene cap line a Jantzen will make a big difference even over a cheaper Solen. You will hear it.


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## Holmz (Jul 12, 2017)

metako said:


> With a series cap the whole of your tweeter signal is going through the cheap cap. Its going to affect the sound quality. A quality polypropylene cap line a Jantzen will make a big difference even over a cheaper Solen. You will hear it.


Is there some evidence that a cheap capacitor does something to the sound?
Like graphs and traces, rather than my uncle Bob told me so.

Otherwise the concept of a cheap capacitor making a cheap sound, might be more like propaganda.


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## metako (May 19, 2012)

Holmz said:


> Is there some evidence that a cheap capacitor does something to the sound?
> Like graphs and traces, rather than my uncle Bob told me so.
> 
> Otherwise the concept of a cheap capacitor making a cheap sound, might be more like propaganda.


I proved this to myself through listening tests using my own ears and not by looking at graphs and traces. But if you'd rather look at traces here's a link I found after a quick google:

The "Sound" of Capacitors

The traces of the electrolytics can be seen via a link half way down. But why not just do the listening experiment yourself and trust your ears? If you can't hear any difference then great - your wallet will thank you. Unfortunately I can hear the difference. If your looking at which caps sound better here is a good place to start:

Humble Homemade Hifi - Cap Test


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## flgfish (Jan 17, 2019)

metako said:


> I proved this to myself through listening tests using my own ears and not by looking at graphs and traces. But if you'd rather look at traces here's a link I found after a quick google:
> 
> The "Sound" of Capacitors
> 
> ...


Neither of those links actually support your argument. Both of them are talking about using capacitors in the frequency range you're listening to (being used as passive crossovers, for example). 

This thread is about capacitors sized so that the effect is outside of the range your crossover is set at in an active network (the capacitor isn't being used a passive crossover network!). The further outside that range, the less the effect. If you can hear it, you've messed up and chosen a bad cap value. You're not actually sending frequencies the cap touches unless you screw up the crossover in the DSP, something breaks, or your amp/dsp does something "bad". And the cap is there to stop the, heaven forbid, "bad thing" from blowing up your tweeter.


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## flgfish (Jan 17, 2019)

One other interesting installation thing to consider, as far as capacitor types go. In the picture, the left one is a 8.2uF 250V Polypropylene cap, the right two are 10uF 50V and 160V electrolytic caps.

The electrolytic are much easier to integrate into an install. They're more durable, as well - the leads on that polypropylene cap are very fragile (you can see the glue being used for strain relief around the shrink-wrap).


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## rob feature (Nov 15, 2015)

I've always gone by a rule of 2 octaves outside the pass band. Not sure where exactly that came from, but the justification for the 2 octave gap was avoiding phase shifts. And I always understood it as at least 2 octaves. I'm using the cheap PE 100 uF electrolytics and no complaints with the tweeters. Caps mounted at the amp. Really digging Alpina's idea above though. 

As far as cheap caps vs pricey caps go (or no cap at all), wouldn't it be easy enough for someone with the right gear to test? You'd be able to see a difference on an oscope if it existed, yeah?...a change in the waveform? Or would it manifest itself in some other way?


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## Holmz (Jul 12, 2017)

metako said:


> I proved this to myself through listening tests using my own ears and not by looking at graphs and traces. But if you'd rather look at traces here's a link I found after a quick google:
> 
> The "Sound" of Capacitors
> 
> ...


Well do Sir.
I'll accept that the ceramics curves look distinctly different and therefore should sound different.

The rest looked linear.


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## planaport (Feb 27, 2018)

Sorry don’t mean to thread jack. But i couldn’t find a consensus whether to cap or not. I ordered AF GS 10 and GS690 and plan on running them active using the crossovers in my Nex 2440. So do I need caps for the tweeters ? If yes which ones ?


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## Hillbilly SQ (Jan 26, 2007)

To the OP-you not liking the Scanspeak tweeters could just be your ears are used to the Focal tweeters. Scanspeak tweeters are known for being warmer sounding and not as sparkly as tweeters like Focal.

To GEM-what's wrong with 4 ohm tweeters? Today's technology makes it easy to pull the levels down to blend with just about anything.


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## GEM592 (Jun 19, 2015)

Hillbilly SQ said:


> To the OP-you not liking the Scanspeak tweeters could just be your ears are used to the Focal tweeters. Scanspeak tweeters are known for being warmer sounding and not as sparkly as tweeters like Focal.
> 
> To GEM-what's wrong with 4 ohm tweeters? Today's technology makes it easy to pull the levels down to blend with just about anything.


There is nothing wrong with 4 ohm tweeters in theory, I find they are practically a little harder to use, and usually the lower impedance doesn't get you much.

This could just be my application. On the other hand, there is probably a reason so many high end manufacturers (Scanspeak excepted) still mainly use higher impedance designs, even for car audio applications. To get an underhung design with minimal mounting depth sure I guess, but how much is that really worth, especially for full-formats that are space hogs anyhow.


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## Hillbilly SQ (Jan 26, 2007)

But how does 4 ohm vs 8 ohm effect the sound of a tweeter? I honestly would like to know. And what does impedance have to do with mounting depth?


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## GEM592 (Jun 19, 2015)

I think a 4 ohm driver will tend to take more power than an 8 ohm driver, more of the power will be in the form of current, the amp will work harder, etc. This makes sense for lower frequency drivers such as subs, where distortion is less of a concern, and mechanical cooling is inherently more available, but I don't see the benefit on the high end. More heat to handle per Watt (without good inherent mechanical cooling), less need for high Wattage anyhow in the higher range, etc. 

Halving the impedance easily allows voice coil height to be reduced, which allows for an underhung design with less mounting depth. Basically, higher impedance drivers will have taller coils, and thus require deeper motors.

These are just generalizations.


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## GEM592 (Jun 19, 2015)

Just generalizations I subscribe to and have found to be true, mind you.  I'm sure there's a way to do a 4 ohm tweeter that would change my life completely.


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## Hillbilly SQ (Jan 26, 2007)

Audiofrog gb10 would probably change your life and it's 4 ohm. There's a reason so many people love them. Only reason I'm not still running mine is because they would have taken fabrication work I didn't want to do.


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## GEM592 (Jun 19, 2015)

They would certainly make walking around easier, as my wallet would be decidedly lighter.

Better than Morel ST 1048, which I'm currently using? I mean in your experience, having heard both in a variety of applications?

I really have no interest in changing tweeters, or really buying anything Audiofrog to be honest. And before you say it, I know I'm missing out. They are a great company, etc.

There are many underhung designs with high impedance and small mounting depth (many high end Focals, for example) out there, but power handling is lower and they are hard to use for different reasons. I guess my generalizations apply more to full-format designs, if anywhere.


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## flgfish (Jan 17, 2019)

planaport said:


> Sorry don’t mean to thread jack. But i couldn’t find a consensus whether to cap or not. I ordered AF GS 10 and GS690 and plan on running them active using the crossovers in my Nex 2440. So do I need caps for the tweeters ? If yes which ones ?


The guy that designed your stuff advocates the cap.

https://www.audiofrog.com/community...p-tweeters-in-systems-with-active-crossovers/

It's a 4 ohm nominal tweeter. Let's say you plan on crossing it over at 4000Hz. Some people shoot for 1 octave lower than that, some 2. So choose a target of 1000-2000Hz. A 22uF cap lands at 1800Hz; that's a standard size and probably a good choice.

Others may have different advice but that's about where I'd be thinking. I put 22uF in series with my Dyna MD-102's.


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## JCsAudio (Jun 16, 2014)

Underhung vs overhung designs in a tweeter discussion seems kind of silly to me because in a driver such as a woofer or subwoofer the voice coil design or architecture are tied into xmax and how much distortion is produced the further the voice coil travels. How much does a voice coil in a tweeter actually travel? I’m no expert, but seems to me that these things become much less important for a tweeter design and the lightness/weight of the voice coil and diaphragm together are more important. 

What I don’t know is if the weight difference between two identical tweeters such as one being 4 ohms and one being 8 ohms really matters. If I look up the specifications of a Satori TW29DN, which are available in 4 ohms and 8 ohms, than I see that the 4 ohms tweeter has a moving mass of .45 grams and the 8 ohm version has a moving mass of .43 grams. The 4 ohm version has a much higher sensitivity rating but worse off axis response. What does this translate into for real word sound differences? This I don’t really know but i’ll guess you can’t really tell and your 75 wpc amplifier won’t care because it will have more than enough power on tap for either.

Obviously you need that protective cap on the tweeter because the voice coil wire is thin and light and bass frequencies carry with them larger currents which would overload the tiny tweeters wire, overheat it quickly, and potentially blow the tweeter. As stated, this can happen with something like a speaker pop. If the tweeter is playing frequencies for which it was designed, than the most it will likely see would be ~ 15 watts. Depending on the crossover point, it may not even get close to that so amplifier requirements should be moot with how cheap amplifier power is today. 

As for the AudioFrog tweeters, I now have them and they are the real deal. I’ve run so many tweeters, both car audio and home audio tweeters in my car and these GB tweeters are very very good sounding. I will say one home audio tweeter that I still have that is damn close to my GB15 (i’m Still evaluating this) is the SB29.


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## Holmz (Jul 12, 2017)

GEM592 said:


> I think a 4 ohm driver will tend to take more power than an 8 ohm driver, more of the power will be in the form of current, the amp will work harder, etc. This makes sense for lower frequency drivers such as subs, where distortion is less of a concern, and mechanical cooling is inherently more available, but I don't see the benefit on the high end. More heat to handle per Watt (without good inherent mechanical cooling), less need for high Wattage anyhow in the higher range, etc.
> 
> Halving the impedance easily allows voice coil height to be reduced, which allows for an underhung design with less mounting depth. Basically, higher impedance drivers will have taller coils, and thus require deeper motors.
> 
> These are just generalizations.


Since the average tweeter maybe uses 1W, the sensitivity of a 4 or 8 Ohm in watts is the same.
And the power handling of a 4-ohm or 8-ohm tweeter being ~1W is much less than mid woofer..
Which all points to 8-ohm, or 16, being more than enough.

The amp cannot work a lot harder with 4-ohm as it is hardly working at all.


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## jrodefeld (Dec 21, 2018)

So, I didn't want to leave this thread hanging after I got so many great replies.

I did end up replacing my capacitors. I'm now using Jantzen Premium Elko caps with a value of 56uF.

This should put the capacitor nearly two octaves below my crossover point so it won't affect the slope but it still should provide enough protection for the tweeters.

The Jantzen brand is a bit more premium, each cap costing about $10 as opposed to $1.50 or so for the PartsExpress caps. For this application it probably doesn't matter but I opted for the more expensive caps for peace of mind.

Anyway, everything is sounding pretty good now. I haven't done any tuning yet, so my EQ is still flat but even so it seems like everything is performing the way it should. I don't know if the other caps actually affected performance, or if I needed more time to "break in" the new tweeters and/or get used to their sound.

Anyway, thanks for the tips regardless.


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## GEM592 (Jun 19, 2015)

Thread summary: No need for low impedance tweets, and no need for blocking caps. But do either if it makes you feel better, to each his own.


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## rob feature (Nov 15, 2015)

I'm going to toy around with the scope tonight & see if I can't see some sort of difference. I don't have any fancy caps lying around, but I do have some cheap PE 100 uF electrolytics that I can compare to nothing at all. 

The idea is to run some power through both setups & observe the waveforms. I'm posting this up in advance fishing for advice or tips on this. I'm going to use test tones at the same level, but am not entirely sure what would be considered appropriate. Maybe 3 kHz as it's near the lower end of where many of us play our tweeters. Also planning to use an old Silver Flute woofer for the load. 

Thoughts?


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## flgfish (Jan 17, 2019)

rob feature said:


> I'm going to toy around with the scope tonight & see if I can't see some sort of difference. I don't have any fancy caps lying around, but I do have some cheap PE 100 uF electrolytics that I can compare to nothing at all.
> 
> The idea is to run some power through both setups & observe the waveforms. I'm posting this up in advance fishing for advice or tips on this. I'm going to use test tones at the same level, but am not entirely sure what would be considered appropriate. Maybe 3 kHz as it's near the lower end of where many of us play our tweeters. Also planning to use an old Silver Flute woofer for the load.
> 
> Thoughts?


That's going to put the first order crossover down near 400Hz with a 4ohm speaker, so you'll need to measure around there & below to see the difference. Just FYI so you know where to look. By all means though, please measure the full range.

I'd use mono pink noise just like you would doing an RTA tune.


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## rob feature (Nov 15, 2015)

flgfish said:


> That's going to put the first order crossover down near 400Hz with a 4ohm speaker, so you'll need to measure around there & below to see the difference. Just FYI so you know where to look. By all means though, please measure the full range.
> 
> I'd use mono pink noise just like you would doing an RTA tune.


Well, the idea is to test it where it'd potentially make an audible difference as a protection cap for a tweeter - not a passive high pass. 

I was hoping to get to this tonight, but wound up working a silly long day and just drove 4 hours back from Colorado Springs (usually under a 2 hour drive) so I'm in no mood to fool with all that right now.


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## Holmz (Jul 12, 2017)

jrodefeld said:


> So, I didn't want to leave this thread hanging after I got so many great replies.
> 
> I did end up replacing my capacitors. I'm now using Jantzen Premium Elko caps with a value of 56uF.
> 
> ...


What are you trying to protect them against?

"2 octave below" is likely well below they would be happy, so it is not protecting them against frequencies that could destroy them, just protecting them against a steady state DC.

Note: I ran the same value, but I cannot conjure a good reason to choose that value.


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## Pb82 Ronin (Jun 6, 2018)

If it helps you OP, I used 22uF caps in my install and my tweets sound fantastic. I don't believe that caps hurt response from tweeters at all, UNLESS you plan on installing a cap that blocks higher "usable" freqs from getting to the tweet. They call them "bass blockers" for a reason. By the math I used the 22 uF blocks any freq below 2600 Hz from getting to my tweet. My X-over is set a 6500 Hz on the low end, so for me, the cap is a non-issue. Also, I get ZERO "speaker pop" from the amp (from the tweets) on start-up.


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## rob feature (Nov 15, 2015)

Finally giving this a go










Not sure what I'm going to be able to present to you folks without a hold function on this old-ass scope, but going to give it a whirl since I dragged it all out anyway. I'm open to suggestions while I have this out, but the idea is to play 3 kHz sine wave created in Audacity and fed through an MP3 player, through one channel of a JL XD 400/4 to a TM65 - monitored by the BK Precision Model 1465 oscilloscope. Just doing a couple runs - with and without the cap. I'm going with quick & dirty this round - just using a handheld phone cam. If it proves unworthy I'll see if I can't get the old Nikon on a tripod & get a better set of photos.

Here goes nothin'


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## rob feature (Nov 15, 2015)

I really do need to put a camera on a tripod so I can get the same images, but here's the 1st go

No cap










100 uF Cap










Pathetic 1st attempt though. Gonna see what I can do to church it up a bit.


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## Holmz (Jul 12, 2017)

If it has a reference input, then the amp side of the cap could go there and the speaker side of the cap into the other input.
That should reference one relative to the other, so an amplitude and phase offset, which gets more linear as the frequency goes up.


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## rob feature (Nov 15, 2015)

Thanks Holmz! There is another input. Not sure if it's a reference input - I don't have a lot of time on this unit, but here's a somewhat better shot of the controls & inputs


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