Crossover reverse calculation? |
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Tweeter_Box
Young Croc Joined: 23 June 2012 Location: London Status: Offline Points: 859 |
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Posted: 23 November 2014 at 12:31pm |
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found a random homemade crossover, seems to be bi-amped, luckily its labelled (hand written on the wodden board), can somebody please tell what freq and slopes its set to, found lots of crossover calculators online but none that will reverse the calculation, thanks in advance
circuit 1. UF 0.82 - MH 0.10 circuit 2. UF 8.2 - MH 2.20 |
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Earplug
Old Croc Joined: 03 January 2012 Location: Europe Status: Offline Points: 7199 |
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Formula is: f = 1/(2*pi*(square root(L*C))
Simple. So I get 1: 17575Hz 2: 1185Hz EDIT: Slopes will be 2nd order, ie 12dB/octave. RE-EDIT: Ooops - just realised I´d misread the values in (1). Edited by Earplug - 23 November 2014 at 2:30pm |
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Earplugs Are For Wimps!
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studio45
Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3863 |
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It would depend entirely on the speakers it was connected to. The impedance of the driver terminates the filter and defines its turnover frequency and damping.
Assuming an 8 ohm speaker, the 8.2 uf/2.2mH combo lowpass filters somewhere around 1000-1500Hz with a 12dB slope. Closest match I could get is 2nd order Bessel for a 10 ohm termination which would be a reasonable impedance to expect at 1200Hz for an average hi-fi woofer. The other combo would highpass filter somewhere around 10000-15000Hz for an 8 ohm driver. SO not sure why they are on the same board. There are free circuit simulation websites where you could draw out the circuit and then examine its frequency response.
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Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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Earplug
Old Croc Joined: 03 January 2012 Location: Europe Status: Offline Points: 7199 |
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Ok, just put my brain in gear a bit...
Circuit (1) is a strange one, but could be for a xover between a 16ohm tweeter and 8 ohm 2", xover point around 12kHz. |
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Earplugs Are For Wimps!
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Tweeter_Box
Young Croc Joined: 23 June 2012 Location: London Status: Offline Points: 859 |
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thanks guys
i tried em yesterday n it would seem one is a low pass (pretty nice sounding actually) using a 600v cap, n the other is a veeery high pass using a 400v cap, dunno how to measure the coils specs though, the high pass only gave real high sizle when put on a 1" but sounded good on a 2" (toned down the vocaly bits nicely)
can you recomend a site please , had a look on my fone n couldnt find much |
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Andy Kos
Old Croc Joined: 15 May 2007 Location: Southampton Status: Offline Points: 3035 |
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http://www.speakerwizard.co.uk/category/speaker-design/2nd-order-crossover-calculator/
Im sure you'll figure out where to put the numbers, once you have worked out which component is which on the diagram, it will do the reverse calculation.. but your numbers seem weird, if they are correct, it looks like they are putting in a massive hole in the response. If your Compression Drive is around 12-15dB more sensitive than the woofer, that will compensate for some of the hole, but effectively give you about 12-15 db boost around 15-20 Khz If there are no attenuation resistors on the HF, this may be part of the design. Bit crude, but it works to give the Boom Tsss disco sound without much mid-range. Kind of creating the smiley face EQ without a graphic.
Edited by Andy Kos - 24 November 2014 at 11:58pm |
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just a guy with a warehouse and a few speakers... www.bluearan.co.uk
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DMorison
Old Croc Joined: 14 March 2007 Location: Aberdeen Status: Offline Points: 1647 |
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CD EQ for a driver/horn combo with quite a sharp HF rolloff?
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Andy Kos
Old Croc Joined: 15 May 2007 Location: Southampton Status: Offline Points: 3035 |
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just a guy with a warehouse and a few speakers... www.bluearan.co.uk
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KidCreole
Old Croc Joined: 06 November 2013 Location: London (East) Status: Offline Points: 3600 |
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Shouldn't the title be. Reverse engineering? What anies cabinets are you cloning now
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Mykey Wattco
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Andy Kos
Old Croc Joined: 15 May 2007 Location: Southampton Status: Offline Points: 3035 |
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Very few manufacturers write inductor values on wooden boards...
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just a guy with a warehouse and a few speakers... www.bluearan.co.uk
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Tweeter_Box
Young Croc Joined: 23 June 2012 Location: London Status: Offline Points: 859 |
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thanks Andy no attenuation on the board, probs coz its bi amped |
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Tweeter_Box
Young Croc Joined: 23 June 2012 Location: London Status: Offline Points: 859 |
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soldering and glue makes me assume its home made, values hand written in pencil on the wood, got 2 diff martin crossovers here to mess around with now aswell, pretty sure one of them was out of the phillishaves i used to own, hopefully i can find some use for them |
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