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Mackie Big Knob Passive

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Mackie Big Knob Passive

Postby ef37a » Fri Mar 05, 2021 9:29 am

I am prompted to raise this matter again because I have recently bought one for my son (works brill he says) and Amazon want a report and I do not want to comment on the controller's shortcomings without giving Mackie a chance to answer some questions I have about the device.

Some here may remember a contributor (forget who, sorry!) told us the controller caused distortion in his particular signal chain? This is caused by the fact that the resistance from 'ring' to sleeve on the input jacks is just 1000 Ohms and that is too low for certain op amps to drive cleanly. In any case, the minimum input load for audio gear has been 10K for many years.

While I had BK in hand and trusty Fluke I checked the Rs around the output jacks. Whoa! Tip to sleeve, 4k7 but ring to sleeve just 150 Ohms. I know of course that the higher figure is just one of the consequences of a passive controller but such resistance differences mean this box should not claim to give a "balanced" output.

I await Mackies reply. Breath? I would not hold it.
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Re: Mackie Big Knob Passive

Postby Hugh Robjohns » Fri Mar 05, 2021 11:13 am


It is perfectly possible to make a properly balanced passive controller with the appropriate input and output impedances... but not for anywhere even remotely close to the kind of money the BK-P sells for.

It's a technically compromised product, inherently -- as are most passive controllers -- but those compromises don't normally cause any real-world practical problems for the majority of users.
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Re: Mackie Big Knob Passive

Postby CS70 » Fri Mar 05, 2021 6:49 pm

Yes, before my D-Box I used to use a MPatch 2 and I must say it served me very well. Of the myriad bad mixing decisions I've made, I can't really say the controller was responsible for any :D
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