Reverse Polarity? |
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AJ113
Registered User Joined: 11 March 2016 Location: Hull UK Status: Offline Points: 123 |
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Posted: 12 October 2017 at 7:58am |
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I was lazily reading through my Tannoy B400 user's manual when I came across this little gem hidden away in a small corner:
Important : always invert the B400 polarity if used with standard reflex loaded loudspeakers 1. So if I use my B400s (folded horns) in combination with reflex boxes I have to switch the polarity? Does this include the mids/tops if they are reflex? Or is it only referring to bass units? 2. Can anyone explain in layman's terms why this is so? I'm guessing it's beause they are horn loaded from the back of the loudspeakers, and therefore would effectively be out of phase with front loaded cabinets? 3. What is the easiest way of reversing the polarity? Swap the connections around at one end of a Speakon cable? |
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Conanski
Old Croc Joined: 26 January 2006 Location: Ottawa, Canada Status: Offline Points: 2543 |
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The idea was that with reversed polarity the horns would "better" sum with reflex boxes but the reality is horns need a lot more processing than a simple polarity flip to properly sum with reflex boxes.
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AJ113
Registered User Joined: 11 March 2016 Location: Hull UK Status: Offline Points: 123 |
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Would I be right in thinking the simplest way is to set the reflex boxes further back from the horns?
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Earplug
Old Croc Joined: 03 January 2012 Location: Europe Status: Offline Points: 7216 |
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Yes, that´s more or less it. You need to measure the horn length and place the relex cabs back that amount. |
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Earplugs Are For Wimps!
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toastyghost
The 10,000 Points Club Joined: 09 January 2007 Location: Manchester Status: Offline Points: 10919 |
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Sure. If you want to be wrong. |
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AJ113
Registered User Joined: 11 March 2016 Location: Hull UK Status: Offline Points: 123 |
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Just playing devil's advocate here a bit:
If I had say, two horns and two reflex cabs, and I set them up as a centre cluster, reflex cabs side by side and a horn either side of them, would that create a line/array, without the need to actually physically line them up in an arc? |
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AJ113
Registered User Joined: 11 March 2016 Location: Hull UK Status: Offline Points: 123 |
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Edited by AJ113 - 13 October 2017 at 6:49pm |
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Conanski
Old Croc Joined: 26 January 2006 Location: Ottawa, Canada Status: Offline Points: 2543 |
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What reflex boxes do you have and what kind of processing(EQ, crossover) do you have available?
According to the specs the B400 is only usable down to 60hz so it's entirely possible your reflex boxes could go significantly lower. If that is the case then using the b400s as kick bins crossed higher than the reflex subs may be the way to go. |
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corell
Young Croc Joined: 19 August 2013 Location: Berlin Status: Offline Points: 1161 |
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Measure Group Delay (or phase) around the x-over frequency. You will most probably notice that a BR enclosure is far from 0ms group delay.
Actually, in some cases where i had to mix FLH and BR (because customer wanted me to), i had to delay the FLH to the BR for the best solution, because it was a BR with a very high Q tuning. |
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Darkstar
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Because he always does and repeating the same things over and over can be tiresome, there's plenty of threads with this topic in which he pointed out how to do it right. Problem is the search function on this forum is a mess, just tried finding a link for you and I can bet I wouldn't find it after a full day of searching. In short you need equipment that can measure all you need to align your speakers, going the rough way can only help mitigate cancellation but will likely mess up other things. Edited by Darkstar - 14 October 2017 at 5:22am |
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Bass =/= Enough
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AJ113
Registered User Joined: 11 March 2016 Location: Hull UK Status: Offline Points: 123 |
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AJ113
Registered User Joined: 11 March 2016 Location: Hull UK Status: Offline Points: 123 |
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So if the B400s and the reflex cabs were operating at separate frequencies, presumably the phase problem is reduced to a minimum? And thinking on... As you say, the B400s are only useable down to 60Hz (although you would never believe that when listening to them!), so does it follow that there would be little in the way of phase issues below 60Hz, regardless of anything else? |
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