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2x15" front loaded horn F2B

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citizensc View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote citizensc Quote  Post ReplyReply Direct Link To This Post Posted: 12 May 2020 at 10:30am
Is it really much of an issue to add 10 or 15mm depth to the rear chamber to accommodate a wider selection of drivers, as long as you keep the same rear chamber volume? Obviously the external dimensions wont batch a real F2B but if you have no intention of stacking them with existing F2Bs then who cares? 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote concept-10 Quote  Post ReplyReply Direct Link To This Post Posted: 12 May 2020 at 11:19am
Originally posted by citizensc citizensc wrote:

Is it really much of an issue to add 10 or 15mm depth to the rear chamber to accommodate a wider selection of drivers, as long as you keep the same rear chamber volume? Obviously the external dimensions wont batch a real F2B but if you have no intention of stacking them with existing F2Bs then who cares? 

No it's not an issue, it's a good plan and while you are doing it you can get the rear chamber volume correct for the driver you are choosing, though I an not convinced it is 100% accurate to the original it is a very good starting point to make something very special.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 12 May 2020 at 12:07pm

Beyma  15LX60V2

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Post Options Post Options   Thanks (0) Thanks(0)   Quote VECTORDJ Quote  Post ReplyReply Direct Link To This Post Posted: 12 May 2020 at 12:15pm
Hi bob4, Do You have any other plans??

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Post Options Post Options   Thanks (0) Thanks(0)   Quote djeddie Quote  Post ReplyReply Direct Link To This Post Posted: 12 May 2020 at 3:57pm
Originally posted by concept-10 concept-10 wrote:

Originally posted by djeddie djeddie wrote:

Well the outside dimensions match my 'extended' F2B's. And as I've said on this forum before, try them with the PD1550!

It may well do externally but a PD1550 will not fit this plan, including the driver rebate you have about 155mm depth on this drawing, a PD1550 has a total depth of 160mm, I'm convinced this plan is not totally accurate to the original or the stretched ones.
 


There is another trick... and that's to route out a few mil in the access hatch. Wink
Chas n Dave : it's like Drum and Bass but with beards.             E=mc² ±3dB
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Post Options Post Options   Thanks (0) Thanks(0)   Quote levyte357- Quote  Post ReplyReply Direct Link To This Post Posted: 12 May 2020 at 5:06pm


How realistic are the quoted response figures ?

Has anyone tried extending this to 1220mm height, to fit across 2x modern subs?

Looking at drivers, sure it would not be difficult find drivers that match the important TS parms, and adopt chambers accordingly.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote levyte357- Quote  Post ReplyReply Direct Link To This Post Posted: 12 May 2020 at 5:12pm
Originally posted by djeddie djeddie wrote:

Well the outside dimensions match my 'extended' F2B's. And as I've said on this forum before, try them with the PD1550!


Might be good for <150hz, but would it really excel above 200hz?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jimmer Quote  Post ReplyReply Direct Link To This Post Posted: 12 May 2020 at 6:53pm
Flat upto 250 Thumbs Up
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bob4 Quote  Post ReplyReply Direct Link To This Post Posted: 12 May 2020 at 6:54pm
Originally posted by VECTORDJ VECTORDJ wrote:

Hi bob4, Do You have any other plans??


No, nothing of particular interest...... i just acted as a strawman in this case.....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote djeddie Quote  Post ReplyReply Direct Link To This Post Posted: 13 May 2020 at 8:56am
Originally posted by Jimmer Jimmer wrote:

Flat upto 250 Thumbs Up


Can concur with that.
Chas n Dave : it's like Drum and Bass but with beards.             E=mc² ±3dB
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Post Options Post Options   Thanks (0) Thanks(0)   Quote citizensc Quote  Post ReplyReply Direct Link To This Post Posted: 14 May 2020 at 12:52pm
Originally posted by bob4 bob4 wrote:

..aaaaand, first one to calculate and post hornresp inputs gets a cookie Big smile

No need for the cookie, my lock-down baking game has been off the chain! 

My goal here isn't to draw up an exact F2B copy, there is some debate about how exact that plan is and I don't think an exact copy is that useful. A design that suites a wide range of drivers and can be built by a Disco Dave with a circular saw is more my kinda thing. 

I have drawn up a slightly modified version in sketchup with the goal of making the plan easier to build. I have replaced all the 15mm pannels with 18mm, this should have negligible impact as most of that extra wood has gone in to wasted cavity space. I also changed the baffle a little bit. The baffle now consists of a piece of 18mm ply with the driver cutout and rebate stuck to a 6mm piece of ply with the throat adaptor cut in to it. 

With these changes I wouldn't call this a difficult build, id rather build this than a double punisher (iv built 7 of those and they are a pain). 

I am not sure about the method I used to find the hornresp inputs. Below is an image of how I did it, black line is the path and dotted lines are the segments, where I measured the horn diameter. Id love some feedback on this, is there a best practice way of doing it? 
2 drivers @ 4ohm
2 x F2B, 4 drivers @ 8 ohm

Once I get my sim parameters sorted, im happy to sim a number of different drivers. I will also go about increasing the depth of the rear chamber to accommodate more drivers.

Here is a link to the sketchup drawing https://www.dropbox.com/s/1quejvp5zda1b7s/hornresp.skp?dl=0


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Post Options Post Options   Thanks (0) Thanks(0)   Quote djeddie Quote  Post ReplyReply Direct Link To This Post Posted: 14 May 2020 at 3:38pm
One thing to bear in mind with the F2B is that it's a bifuricated horn... meaning it's two throats sharing one mouth, not two throats having "half the mouth" each (for want of a better phrase). Much like a HF horn that has two CD's on it... if you see what I mean.
Chas n Dave : it's like Drum and Bass but with beards.             E=mc² ±3dB
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