Passive high pass filter for tweeters |
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dnbpc
Registered User Joined: 18 March 2010 Location: Manchester Status: Offline Points: 381 |
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Posted: 04 February 2016 at 1:37pm |
If I wanted to make a passive high pass filter for a tweeter box @ 10khz is it as simple as adding a capacitor of a certain value to the circuit or would I have to make a complete crossover? If so can anyone give me a basic explanation of where to start?
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stevie
Registered User Joined: 16 March 2008 Location: Dorchester Status: Offline Points: 425 |
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It's more complicated than that but, yes, you could make a start by adding a capacitor in series with the tweeter. A film capacitor of around 2.2uF should work with an 8 ohm tweeter. Get 3 values 1, 2.2 and 3.3uF and try them out. The Loudpeaker Design Cookbook is very good as a primer on this kind of thing.
10kHz isn't a critical area - so it could work at a pinch. Also try swapping the phase of the tweeter in circuit to see what sounds best. |
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dnbpc
Registered User Joined: 18 March 2010 Location: Manchester Status: Offline Points: 381 |
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Cheers I'll order a few different value capacitors and have a mess about, I'll make sure to check out the book as well.
Am I right in thinking that if I wanted to increase the slope of the filter I would need to add a resistor as well? |
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stevie
Registered User Joined: 16 March 2008 Location: Dorchester Status: Offline Points: 425 |
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You'll need to add an inductor.
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odc04r
Old Croc Joined: 12 July 2006 Location: Sarfampton Status: Offline Points: 5483 |
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Not necessarily. A first order high pass can be made using a single series capacitor. Start simple.
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stevie
Registered User Joined: 16 March 2008 Location: Dorchester Status: Offline Points: 425 |
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You'll need to add an inductor (rather than a resistor) if you want to increase the slope of the filter.
Edited by stevie - 04 February 2016 at 6:08pm |
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_djk_
Old Croc Joined: 23 November 2004 Location: United States Status: Offline Points: 6002 |
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I would not use a crossover with less than a 12dB slope.
1.5µF + 0.4mH = 10Khz Q=.5 (Linkwitz/Riley) |
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djk
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dnbpc
Registered User Joined: 18 March 2010 Location: Manchester Status: Offline Points: 381 |
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Right I think I've got a better understanding, so to get a 10khz 12db slope I would connect a 1.5µF capacitor and a 0.4mH inductor in series before the tweeter?
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markie
Old Croc Joined: 31 October 2005 Location: Sunny Liskeard. Status: Offline Points: 4570 |
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The cap goes in series with the tweeter but the inductor goes in parallel. This will give you an idea:-
http://www.diyaudioandvideo.com/Calculator/SpeakerCrossover/ Edited by markie - 05 February 2016 at 4:26pm |
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tv00
Old Croc Joined: 10 August 2009 Location: Denmark Status: Offline Points: 1886 |
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There's lots of crossover calculators out there, I'd do a 18/db slope one, takes a few components but for a electronic circuit it's very simple, components are big though, use at least 100V components, probably more, depending on power, so they don't blow up.
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MarjanM
Old Croc Joined: 10 February 2005 Location: Macedonia Status: Offline Points: 7810 |
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Crossovers are not made with calculators but with measurements.
Calculators assume a flat line response which never is. What is below the tweeter? Is sensitivity matched to the rest of the components?
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Marjan Milosevic
MM-Acoustics www.mm-acoustics.com https://www.facebook.com/pages/MM-Acoustics/608901282527713 |
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tv00
Old Croc Joined: 10 August 2009 Location: Denmark Status: Offline Points: 1886 |
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You still have to calculate the xover rather than connecting random components!
You're right, sensivity has to match +impedance has to match the xover, also a hard part is to get a smooth transition, drivers might couple /decouple at xover as phase also gets twisted. I really don't know too much about this, but I saw a couple of interesting posts about this. |
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