Jack10 passive crossover questions

The Jack of All Trades pro-sound cabs.
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monekh
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Joined: Mon Mar 31, 2014 5:56 pm
Location: London, UK

Jack10 passive crossover questions

#1 Post by monekh »

Hi again!

I am in the process of building two Jack10s as a summer project with some kids at a local adventure playground. They want to be able to use the speakers in spaces without mains power, so we are hoping to power them using a 12v battery and a car amplifier.

The build is going well so far, but I am a bit nervous about building the passive crossovers as I have only ever bi-amped before... so I have a few questions.

- With the choice of inductor coils being affected by load impedance, does this mean we would need to wire everything in series if we want to leave the option of daisy chaining cabinets in future?

- The coils needed for a Jack 110 with ASD1001 are 0.45mH, 0.6mH and 0.9mH. The easiest place for me to buy them so that they arrive in time only seems to only supply 0.47mH, 0.68mH, 0.82mH and 1.0mH. Can we get away with using these values instead? And if so, is it better to go under (0.82) or over (1.0) in place of the 0.9mH coil?

- As the cost of the coils is quite high, I am considering instead getting one of these 12v DSPs - https://www.thomann.de/gb/the_t.racks_dsp_4x4_mini.htm - and a 4 channel amp, and bi-amping. I realise we would lose the flexibility of being able to plug a passively crossed-over box into any 2 channel amplifier... but it would save us time and faff building the crossovers, and give us better control over the output. Are there other reasons not to go the DSP route in this situation?

Thanks!

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Bill Fitzmaurice
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Re: Jack10 passive crossover questions

#2 Post by Bill Fitzmaurice »

The only load the crossover sees is that of the drivers in its own cabinet. The plans state 'A value tolerance of plus or minus 10% is acceptable'. If the cost of the inductors is high you're looking in the wrong places and/or at the wrong components. This is an example of an appropriate 1 mH coil: https://www.parts-express.com/Dayton-Au ... or-257-650

monekh
Posts: 90
Joined: Mon Mar 31, 2014 5:56 pm
Location: London, UK

Re: Jack10 passive crossover questions

#3 Post by monekh »

Thanks Bill - sorry had misinterpreted value tolerance. That's good news though.

monekh
Posts: 90
Joined: Mon Mar 31, 2014 5:56 pm
Location: London, UK

Re: Jack10 passive crossover questions

#4 Post by monekh »

I know the plans specify using an electrolytic capacitor for the woofer low pass filter, but is it possible to use polypropylene instead, or is there a specific characteristic to electrolytic capacitors that makes them better suited to this application?

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Bill Fitzmaurice
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Re: Jack10 passive crossover questions

#5 Post by Bill Fitzmaurice »

Compare the prices. You may use poly, but in a low pass filter it won't work any better while costing a lot more.

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