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Author Topic: Push pull configuration for LAB Horn?  (Read 18084 times)

Tim McCulloch

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Re: Push pull configuration for LAB Horn?
« Reply #40 on: August 28, 2007, 02:01:25 am »

Thank you for that stunning insight into subwooferdom.  Please drive thru.

Tim Mc
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Grant Rider

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Re: Push pull configuration for LAB Horn?
« Reply #41 on: August 29, 2007, 11:32:27 am »

Tim McCulloch wrote on Thu, 23 August 2007 15:30

30 years ago *we* got our start the really old-fashioned way: at the library.  It's the lack of preparation that probably chaps my ass more than any other single thing.  Posting a few questions on internet forums is NOT research, studying, or preparation, although it might lead to that...

Good suggestion. Check the air in your tires.
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Tim McCulloch

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Re: Push pull configuration for LAB Horn?
« Reply #42 on: August 29, 2007, 02:18:56 pm »

Grant Rider wrote on Wed, 29 August 2007 10:32


Good suggestion. Check the air in your tires.


Always a good idea.  Safety and economy.

Tim Mc
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"Will you stand by me against the cold night, or are you afraid of the ice?" Crack The Sky

Grant Rider

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Re: Push pull configuration for LAB Horn?
« Reply #43 on: October 11, 2007, 11:59:30 am »

 http://srforums.prosoundweb.com/index.php/mv/msg/24934/25264 1/0/#msg_252677

Tom Danley admits to "a certain friction which goes way back" but says he "was thinking of sending a new box (to the Tulsa sub shootout) but the first samples, while impressive sounding, were I felt too far short of the computer model".

Maybe we are seeing an end to the friction?

Tom Danley wrote on Tue, 09 October 2007 23:49

I have sent speakers to shootouts before and think proper measurements and side by side comparisons vital in getting to reality.  Personally Wayne and I seemed to exhibit a certain “friction” which goes way back and my daughter has surgery that weekend so I couldn’t go anyway.
I was thinking of sending a new box but the first samples, while impressive sounding, were I felt too far short of the computer model.    I (hope) figured out what wasn’t right and have a second set in the works.  These boxes should in a stack of 4 have about 10dB of forward directivity gain in addition to sensitivity and a lower cutoff, but hey, they aren’t measured yet.


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Wayne Parham

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Re: Push pull configuration - measurement data
« Reply #44 on: October 25, 2007, 12:28:38 pm »


I've compiled some data that shows the benefits of push-pull drive.  Response and distortion charts taken from the last few Prosound Shootouts are lined up side by side for easy comparison:

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Wayne Parham
π Speakers
PiSpeakers.com

Ivan Beaver

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Re: Push pull configuration for LAB Horn?
« Reply #45 on: October 26, 2007, 07:21:13 am »

The 2nd version of that model Tom was talking about works much better.  It is 30Wx48Tx26 deep (smaller than a lab sub and easy to move and great truck pack).  Output @30Hz with 2.83V input is over 102dB.  Combine that with 2000watt RMS power and you have an idea that it will get VERY loud and low!
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Can I have some more talent in the monitors--PLEASE?

Ivan Beaver
dB Audio & Video Inc.
Danley Sound Labs

Wayne Parham

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Re: Push pull configuration for LAB Horn?
« Reply #46 on: October 26, 2007, 10:58:41 am »


Ivan Beaver wrote on Fri, 26 October 2007 06:21

The 2nd version of that model Tom was talking about works much better.  It is 30Wx48Tx26 deep (smaller than a lab sub and easy to move and great truck pack).  Output @30Hz with 2.83V input is over 102dB.  Combine that with 2000watt RMS power and you have an idea that it will get VERY loud and low!


Too bad you didn't bring it to the Prosound Shootout.  Would have loved to see you there.

Did you notice how little distortion the 12Pi had?  Even when pushed to extreme power levels, the distortion is down at the levels of the noise floor.  Most basshorn subs have distortion that's louder than the fundamental at very low bass frequencies near horn cutoff.  The 12Pi doesn't, distortion remains low at high power even at the deepest bass frequencies.  I think that clearly shows the benefit of using push-pull drive.

One thing you notice right away is how most horns make a throbbing, whooshing, sometimes a thumping sound way down low.  I'm not talking about the jackhammer sound of the voice coil hitting the plate, I'm talking about LF distortion.  It is pure distortion, down way under the horn cutoff frequency where the fundamental is very quiet but harmonics are amplified by the horn.

The 12Pi basshorn is dead quiet when driven by signals under cutoff.  When the frequency is raised into the passband, the horn comes alive.  No distortion.

Most people don't run basshorns under the flare frequency.  Some do.  But everyone runs them down as low as possible, and the distortion reduction from push-pull drive is clearly evident in the passband, especially at the lower end.  I don't think I'd ever build a basshorn with two drivers that didn't use push-pull drive.  That's one of the biggest advantages of having two drivers, in my opinion.
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Wayne Parham
π Speakers
PiSpeakers.com

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