Passive crossover design |
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Modeller
Registered User Joined: 03 March 2016 Location: UK Status: Offline Points: 31 |
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Posted: 19 April 2016 at 12:37am |
Hello, I'd like to design a passive crossover for a modelling project I have underway at the moment.
I have two drivers, both with a limited acoustic range, but because of space constraints these are the only ones I can use. The bass/mid driver tails off dramatically at about 10kHz down to 13kHz and the tweeter starts at approx 2kHz to 20kHz. I'd like to have my crossover engage the tweeter at around 8-9Khz. Is there a simple PCB design using standard components that I could build to these specs? Any help you could give would be much appreciated. Steve
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Conanski
Old Croc Joined: 26 January 2006 Location: Ottawa, Canada Status: Online Points: 2543 |
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There are all kinds of textbook crossover design tools on the web that will show you what component values are needed to generate your crossover. Designing a passive crossover that sounds good goes way beyond a basic crossover though, and that is because the acoustic result is the product of the output from the crossover and the speakers they are attached to which usually have a response that is far from textbook. And you may also want to consider the polar response(horizontal coverage) you want to achieve when selecting a crossover frequency, the response of low frequency drivers narrows to a beam in front of the driver at pretty low frequencies, a 15" beams above 1khz for example, a 12" at 1.2khz and that is why most PA speakers systems have relatively low crossover frequencies. If you don't care at all about off axis coverage then use whatever crossover frequency you want.. higher is better for high frequency drivers, I'm trying to make you aware of of the tradeoff you are making.
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haymere
Young Croc Joined: 28 December 2007 Location: Liverpuddle Status: Offline Points: 585 |
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I want to do the same thing but a much more common scenario at say 1.6khz
Can you post some links Also where is best to get quality components in the uk |
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Earplug
Old Croc Joined: 03 January 2012 Location: Europe Status: Offline Points: 7216 |
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Take your pick:
https://www.google.es/search?q=crossover+design&ie=utf-8&oe=utf-8&gws_rd=cr&ei=vPEVV6jJOoGoa7iwk_AO#q=crossover+design+calculator Edited by Earplug - 19 April 2016 at 9:56am |
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Earplugs Are For Wimps!
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Modeller
Registered User Joined: 03 March 2016 Location: UK Status: Offline Points: 31 |
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Thanks Conanski and especially Earplug for the link.
Using the first link in the search it came up with a very simple crossover, attached below. This crossover links two 8 Ohm drivers at 8kHz. My application is a very low fidelity project – we're not talking audiophile quality. The sounds I'll be reproducing are engine, mechanical and environmental sounds, rather than expansive musical tone, so this simple layout seems to suit my application. One more question – where do I buy the parts? |
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Earplug
Old Croc Joined: 03 January 2012 Location: Europe Status: Offline Points: 7216 |
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Blue Aran:
http://www.bluearan.co.uk/index.php?id=CNVMPC25082_4PK&browsemode=manufacturer (Use 3 in parallel) http://www.bluearan.co.uk/index.php?id=CNVFCS016&browsemode=manufacturer Monacor: http://www.monacor.co.uk/categories/film-capacitors/vnr/112300/ http://www.monacor.co.uk/categories/air-core-coils/vnr/124760/ |
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Earplugs Are For Wimps!
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Andy Kos
Old Croc Joined: 15 May 2007 Location: Southampton Status: Offline Points: 3038 |
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This is very close to being ready to launch for public use:
just chuck in what you want on the left, and it will tell you what need from standard parts. If you're more interested in the technical side of things, try this: it's all work in progress at the moment, feel free to contact me with any feedback/comments. Edited by Andy Kos - 20 April 2016 at 10:44pm |
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just a guy with a warehouse and a few speakers... www.bluearan.co.uk
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studio45
Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3864 |
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The various wizards (that's a very good one by the way Andy, thanks!) make calculating your basic filters very easy, you shouldn't have any problems there. I charged right into the field that way before I even understood what an inductor does. However, all my first attempts sounded pretty terrible, even though I used the right filter components. It was this point that I realised there were several important things I had to understand, as well as the basic filters:
-L-Pads -Asymmetrical filters (Highpass and lowpass at different frequencies) -Notch filters -Zobel networks -Shelf filters (aka "baffle step correction") -Series resonant filters to equalise HF response -importance of proper winding technique (if making your own coils). -the differences between cheap and expensive capacitors, in terms of sound and longevity. -Speaker dispersion and how it should influence choice of crossover point. If you want to really understand, be prepared to read up on all or most of that ^^. |
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Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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DJ-Versatile
Registered User Joined: 04 March 2013 Location: United Kingdom Status: Offline Points: 392 |
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Sorry to hi-jack this thread a little, but I have a question or two. For instance if i'm making a Sub and a full range box and wanted to HPF the sub at 35hz and LPF at 120 hz, then HPF the full range box at 120 hz.
I would need to build 2 crossovers rated at 8 ohms with the above values to put in the dedicated box. Would the Amp then see 4 or 16 ohms? The aim is to get it to a 4 ohm load.... help me... my eyes have gone square from staring at the screen!
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If you are the smartest person in the room, you're in the wrong room....
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odc04r
Old Croc Joined: 12 July 2006 Location: Sarfampton Status: Offline Points: 5482 |
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When a passive crossover is working in its passband, it contributes effectively a zero resistance in series with the driver assuming no other eq etc is built in.
I advise getting LTspice and learning how to use it to sim crossovers with AC and transient analysis. Little bit of a learning curve but all the parts you need are as basic as it gets so drawing out the schematic is easy enough. |
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Andy Kos
Old Croc Joined: 15 May 2007 Location: Southampton Status: Offline Points: 3038 |
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Edited by Andy Kos - 28 April 2016 at 3:58pm |
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just a guy with a warehouse and a few speakers... www.bluearan.co.uk
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DJ-Versatile
Registered User Joined: 04 March 2013 Location: United Kingdom Status: Offline Points: 392 |
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Thanks, i'll look into it now!
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If you are the smartest person in the room, you're in the wrong room....
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