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Three Pi and Three Pi Sub Plans [message #91007] Wed, 02 October 2019 14:22 Go to next message
timothyeyster is currently online  timothyeyster
Messages: 2
Registered: October 2019
Esquire
Hi, Wayne.

Firstly, thanks for sharing all of this fantastic information and for providing your products to the DIY community!

Secondly, I purchased a pair of your H290C waveguides yesterday to go with a pair of DE250s I have (thanks for shipping those so quickly, by the way), and would love a copy of your plans for the Three Pi and the Three Pi Subwoofer to look over. Could you also please point me toward the appropriate crossover schematics/layouts?

Lastly, when I decide which woofer I'd like to use in my builds, is that something I could purchase from you a-la-carte, or do you only sell those packaged within the kits?

Thanks again,

Tim

Re: Three Pi and Three Pi Sub Plans [message #91013 is a reply to message #91007] Thu, 03 October 2019 09:03 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17570
Registered: January 2001
Illuminati (33rd Degree)

We don't sell partial kits or raw drivers. But we do well the crossovers individually (assembled or unstuffed) for those that want to source their own drivers.

I'll send plans directly to your email address. The plans include the crossover schematic.
Re: Three Pi and Three Pi Sub Plans [message #91068 is a reply to message #91013] Sat, 12 October 2019 16:49 Go to previous messageGo to next message
timothyeyster is currently online  timothyeyster
Messages: 2
Registered: October 2019
Esquire
Wayne,

Thanks for sending those over!

The 3Pi design is really elegant, and, I'm convinced, would perform incredibly well. Unfortunately, after much consideration, I just don't think it will shoehorn into my space due to the cabinet size.

I started modeling alternative boxes in WinISD, and think I found a good compromise: Using the B&C 12PLB100 woofer you've identified, I tried B&C's recommended box size of 1.41 cuft tuned to 52HZ, and came up with a ruler-flat response to 60HZ that then slopes quickly to -3db at 50HZ. This seems like acceptable low frequency cutoff to me, especially if used with flanking woofers.

However, after reading your thinking behind the larger box with the EBS alignment, and how it's meant to play lower and integrate better with flanking woofers, I'm wondering if I'd lose more than just a little low end extension using this smaller box. I'm also wondering if I were to change the box alignment, if a substantial redesign of the crossover will also be required.

Having already gotten so much great information from you and this site, I feel bad asking for more. But, if you would be willing to share your thoughts on this, or point me toward further reading, I'd sure appreciate it.

Thanks again,

Tim
Re: Three Pi and Three Pi Sub Plans [message #91083 is a reply to message #91068] Mon, 14 October 2019 10:37 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 17570
Registered: January 2001
Illuminati (33rd Degree)

What you propose sounds like it would work pretty well. You would lose a couple synergies that are designed into the three π and four π models though. And you would need to test your design with acoustic measurements, paying special attention to the lower midrange. I think you'd be alright there though, because your cabinet is small enough that it would have relatively high-frequency standing waves inside, and those would be attenuated the fiberglass stuffing material. The standing waves are potentially problematic in larger cabinets.

The synergies I'm talking about are matching the baffle step with the flanking sub rolloff, which both conjugates baffle step and mitigates higher-frequency room modes and self-interference notches from nearest boundaries. This is what you get from the existing three π and four π designs when used with flanking subs.

A smaller baffle will have baffle step higher in frequency, and you wouldn't want to run flanking subs high enough to fill in that gap. So there will be a little bit of a droop between the flanking sub upper frequency and the baffle step frequency.

But you might still give it a go. I wouldn't try to compensate for baffle step with an electronic filter, I'd just live with the droop and see if it was objectionable. My guess is it would sound just fine.
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