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Old 12th November 2012, 07:00 PM   #11
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I would agree with Art on the distortion harmonics thing. Keeping 2nd higher than 3rd is a good thing.

I do try to do woofer sections with push-push drivers, as this goes a long ways to taking the box out of the equation.

dave
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Old 12th November 2012, 08:03 PM   #12
hoppaz is offline hoppaz  United Kingdom
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Taking aside the 2nd harmonic cancellation of the sub box/driver design what if you power said sub design that has a amplifier power source that is maybe designed deliberately to re-inforce said 2nd order harmonics? Does this give you the perfect sub?
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Old 12th November 2012, 08:11 PM   #13
tb46 is offline tb46  United States
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Hi Y'all,

Even though it does not directly address the original question, it may be interesting to note that if you combine push-pull with the ACE BAss feedback concept (e.g.: Patent #4118600) you would get more than just 2nd order cancellation, and maybe that would be the way to go if you are really concerned about subwoofer distortion.

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Old 12th November 2012, 10:31 PM   #14
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Quote:
Originally Posted by hoppaz View Post
Taking aside the 2nd harmonic cancellation of the sub box/driver design what if you power said sub design that has a amplifier power source that is maybe designed deliberately to re-inforce said 2nd order harmonics? Does this give you the perfect sub?
A "perfect" sub or sub amplifier would have no distortion.

An amplifier or speaker designed to increase harmonic content may be OK when used for a musical instrument. The Ampeg SVT, a 300 watt tube amp typically using 8 x 10" speakers sounds great for bass guitar, but I would not want to listen to it for low frequency reproduction.

There are effects such as MaxxBass that increase the even order harmonic content of low bass, giving a sonic illusion of the missing fundamental.
As they say at the midway, close but no cigar, after hearing real clean bass down in the 20-30 Hz range sonic illusions don't make the grade.

Art
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Old 14th November 2012, 11:01 AM   #15
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I'll only build push pull subs.
They sound better and are harder to localize.
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Old 14th November 2012, 04:35 PM   #16
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Quote:
Originally Posted by norman bates View Post
I'll only build push pull subs.
They sound better and are harder to localize.
Norman,

Better sounding and harder to localize than what?

A push pull using Eminence Lab 12" speakers pushed hard is quite easy to localize due to the vent noise.

Push-pull mounting can certainly benefit some speakers, but not all.

Art
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Old 14th November 2012, 11:16 PM   #17
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Better sounding than non push pull given the same design.
We are not comparing sealed, ported, tranny lines, that's a different can of worms.

In a single subwoofer, the upper harmonics are easier to hear as the loudness increases, simple harmonic distortion. Say you have 110db @ 80hz. A sealed non-push pull may be 90db or more at 160hz (it should be zero) while the push pull may be 20-40db lower. I'll have to dig to find the testing graphs.

The drivers' distortion is reduced.
Bass sounds more like organ bass instead of chunky distorted in your face bass.
I'd been told the cheaper the driver, the more the improvement.

But things like vent noise, a push pull cannot fix that.

Norman
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Old 15th November 2012, 07:06 AM   #18
hoppaz is offline hoppaz  United Kingdom
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Has anyone use this type of design in conjunction with Stahl's Ace Bass theory? I would imagine it would be pretty low on the distortion front?.
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Old 15th November 2012, 08:24 AM   #19
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by hoppaz View Post
Has anyone use this type of design in conjunction with Stahl's Ace Bass theory? I would imagine it would be pretty low on the distortion front?.

Hi hoppaz,

Nearly 40 years ago I designed and made quite a few ACE-bass based Subs using push -pull drivers, but today I think it's a moth-point:
There are many good drivers with sufficiently low distortion characteristics that when used at excursion levels with a margin lower than x-max performs blameless.

b
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Old 15th November 2012, 08:34 PM   #20
hoppaz is offline hoppaz  United Kingdom
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Thanks for the replies Gents. By the way Bjorno that was some goal by Zlatan last night!
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