capacitors inline with tweeters |
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msoundsystem
Young Croc Joined: 10 November 2011 Location: wales Status: Offline Points: 625 |
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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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Earplug
Old Croc Joined: 03 January 2012 Location: Europe Status: Offline Points: 7216 |
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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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msoundsystem
Young Croc Joined: 10 November 2011 Location: wales Status: Offline Points: 625 |
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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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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5175 |
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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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Elliot Thompson
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Earplug
Old Croc Joined: 03 January 2012 Location: Europe Status: Offline Points: 7216 |
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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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msoundsystem
Young Croc Joined: 10 November 2011 Location: wales Status: Offline Points: 625 |
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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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jbl_man
Moderator Group Joined: 12 January 2005 Location: London. Status: Offline Points: 11155 |
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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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Be seeing you.
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Earplug
Old Croc Joined: 03 January 2012 Location: Europe Status: Offline Points: 7216 |
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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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msoundsystem
Young Croc Joined: 10 November 2011 Location: wales Status: Offline Points: 625 |
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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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Earplug
Old Croc Joined: 03 January 2012 Location: Europe Status: Offline Points: 7216 |
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Dub Specialist Sound
Old Croc Joined: 15 November 2013 Location: Smethwick Status: Offline Points: 4873 |
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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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I-shen Soundboy
Registered User Joined: 21 December 2016 Location: Big Smoke Status: Offline Points: 375 |
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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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