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capacitors inline with tweeters

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msoundsystem View Drop Down
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    Posted: 16 April 2017 at 2:01am
Hi all. Installing 4x 8ohm bullet tweeters in series/ parallel to make 8 ohms. I think it's 2.2uf cap that came on each tweeter. My question is, is it better to have one capacitor on each tweeter on the positive side of the tweeter or would i be able to put just one cap on the first tweeter and the rest will be ok or is it better to have indavidual caps on each tweeter? many thanks
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2017 at 10:07am
What  are the capacitors supposed to be doing? For protection, or setting the crossover point? Just using a single capacitor as the crossover is pretty basic and not very effective. Maybe ok for a small home hifi cab, but terrible for a big system.

2.2uf gives you a first order slope at around 9kHz, which may be ok for the bullets, but they will still be receiving substancial 900Hz signal. Not good. The best is to get rid of them and either use an active crossover, or a decent passive HPF placed before all the tweeters.

If you´re after some protection, you´ll need a larger (around 22uf) capacitor, again placed before the network of bullets.




Edited by Earplug - 16 April 2017 at 10:08am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote msoundsystem Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2017 at 10:31am
Sorry should of said they are being cut at 7k on processor. Caps It's what came with them, iv always installed them on every set iv had with no issues. Just added protection I guess. One cap on input or one cap on each tweeter is what I'm wondering.. Thanks mate
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2017 at 11:03am

Hi.

You will need one capacitor per pair as you are following the series-parallel scheme. Bear in mind the resistance of two speakers wired in series will increase so, you will need to recalculate the proper capacitor to attain the same roll-off point as if you were wiring one tweeter parallel. 

You can also calculate the total resistance of all the tweeters wired in the series-parallel scheme and, use one large (in value) capacitor. 


Best Regards, 



Edited by Elliot Thompson - 16 April 2017 at 11:04am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 16 April 2017 at 3:22pm
Originally posted by msoundsystem msoundsystem wrote:

Sorry should of said they are being cut at 7k on processor. 


Then those 2.2uf are going to interfere horribly with the phase - get rid of them and just put one capacitor in line.

Have a look here:

http://forum.speakerplans.com/amplifier-dc-on-2-hf-drivers-coupling-caps_topic98242.html


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Post Options Post Options   Thanks (0) Thanks(0)   Quote msoundsystem Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2017 at 8:29am
In what way will they interfear with the phase? What value would you recommend for one cap inline on 4 tweeters? Each tweeter receiving 100watts ish, the link u sent me had the voltage of caps,not the UF. Cheers for the help.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jbl_man Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2017 at 8:58am
The one situation where i would use caps for HF protection is on bullet tweeters,just to protect against wrong connection,ie,plugging them into the mid amp section by mistake etc,it can happen. Or of course your DSP crossover going tits-up and frying them.

If you must use capacitors,use the pukka hi-fi grade audio caps (non-polarised),they tend to be quite pricey for what they are,but should give you some peace of mind.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2017 at 10:11am
Originally posted by msoundsystem msoundsystem wrote:

In what way will they interfear with the phase? What value would you recommend for one cap inline on 4 tweeters? Each tweeter receiving 100watts ish, the link u sent me had the voltage of caps,not the UF. Cheers for the help.


You´re crossing over at 7kHz (BTW, is that active or passive?) - and then adding in another -3dB point at 9kHz. That´s pointless and obviously will add an extra, unnecessary phase shift.

Use a decent 15uF or 22uF capacitor for overall protection.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote msoundsystem Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2017 at 10:47am
It's passive mate. Thanks for the help. Will give 22uf ago! Will post results when iv made these mods. Peace ✌
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 17 April 2017 at 1:04pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dub Specialist Sound Quote  Post ReplyReply Direct Link To This Post Posted: 18 April 2017 at 9:06pm
Dont yu mean 1.5uf 2.2uf 

??

going by catulator chart 2.2uf is around 9k

maybe me the way i understand it 


Edited by Dub Specialist Sound - 18 April 2017 at 9:06pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote I-shen Soundboy Quote  Post ReplyReply Direct Link To This Post Posted: 18 April 2017 at 10:27pm
Yup, 22uf gives a 6db slope at 900hz For an 8 ohm driver.
So no attenuation above 900hz and precious little below.

22uf would be OK as a DC protection capacitor for tops ACTIVELY crossed at 1.6k or above. Useless as a 1st order passive for anything less than a very quiet 2". And even then...
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