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Compound loading 6th order quarterwave "Super Planar" horns and pipes concepts/builds
Compound loading 6th order quarterwave "Super Planar" horns and pipes concepts/builds
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Old Yesterday, 10:37 AM   #351
Matthew Morgan J is offline Matthew Morgan J  United States
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Quote:
Originally Posted by USRFobiwan View Post
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This is also an option.
Obi ,
Good one! I will save this in my collection of fold options..

It is good to have a lot of fold or layout options that we can to turn to... Makes it easier to find a fold that fits the path length and dimension requirements of a project when you have so many options to choose from......
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Old Yesterday, 04:20 PM   #352
Matthew Morgan J is offline Matthew Morgan J  United States
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Lightbulb Procedure

Quote:
Originally Posted by USRFobiwan View Post
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When modeling one of these Compound RLH/BLH designs in Hornresp the secret is to stagger the resonances in the right order and with fairly even spacing ... I will provide an example below...

If we are wanting a subwoofer cabinet with a tuning in the mid 30s there will be another strong resonance that falls in the 65hz to 75hz range as long as we have provided enough expansion in the main path (some believe this is a separate quarterwave resonance but it may also just be the Fb*3 harmonic shoved downward into our working range and made prominent due the path's expansion, either way it is very useful to us) ............................................. Next we want to tune the length of the short resonator, and i am referring to the resonator in which our driver's motor is located (in the above sketch)... This resonator is what i call the front chamber (but is referred to as the "rear vented" chamber in Hornresp) .... Adjust the length of that resonator (i adjust "Lpt" in my models for this) so that this resonance lands right between our 70hz-ish resonance mentioned previously and the next odd harmonic up (Fb*5 shifted down) which will usually end up right around the vicinity of 115 to 130hz so we should tune our front chamber to around 90hz to 100hz ... Perform this fine tuning in Halfspace (2pi) and using either the impedance graph zoomed in or the "Diaphagm Displacement" (cone excursion) graph you should be able to easily see what is going on with the dips corresponding to our resonances.

So if all goes well we could end up with resonances at 35hz, 70hz, 90hz, 120hz .....
The first three resonances are most important as they are all at play well within our working range ..... Output up around 120hz is generally not as strong (in sim) especially with multiple cabinets or additional boundary gain, and the midbass response hole is located just above that harmonic ....
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Old Yesterday, 05:45 PM   #353
Matthew Morgan J is offline Matthew Morgan J  United States
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Exclamation Now for something truly extreme

For fun , and just to see if it would work (in sim) ...

I made this cabinet a little larger than necessary in an attempt to eek out a little more efficiency ...

We are dumping 5000 watts into this iPAL and it is just starting to approach Xmax .... The rating is 22mm and we are hitting 20mm at 5000w ...

This is a lot of pressure for a 21" cone ... I wonder if it would survive?


This is a cool novelty and all but honestly two of the Super Planar 8th 600 liter cabinets (1200 liter total) loaded with the 18DS115 at 3400 watts for the pair do just as well as a single iPAL 21 cabinet (883 liters as featured here) at 5000 watts ....... The curve is almost an exact match in fact ....
The two 18DS115s cost less , but two of them do require more cabinet volume than the single iPAL ...


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Old Yesterday, 06:00 PM   #354
BP1Fanatic is offline BP1Fanatic  United States
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Where is the impedance curve to show the multiple resonances?
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Old Yesterday, 07:11 PM   #355
Matthew Morgan J is offline Matthew Morgan J  United States
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Talking Here you go!

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Originally Posted by BP1Fanatic View Post
Where is the impedance curve to show the multiple resonances?

Here it is BPIFan

As requested


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