Question about change in plans

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EduBH1978
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Joined: Tue Sep 04, 2018 3:12 pm

Question about change in plans

#1 Post by EduBH1978 » Sun Sep 16, 2018 3:22 am

I know it sounds stupid, but... I can deal with woodwork and math, but not with designing the cabinet, so...

If I change the external measures (depeer, wider box) keeping the same internal volume and the same tuning (also changing the ports for round types), should I expect the same results with the same drivers in the plans?

Thanks!

Grant Bunter
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Re: Question about change in plans

#2 Post by Grant Bunter » Sun Sep 16, 2018 3:59 am

Hi and welcome to the forum :)

Which plans are you talking about?

The folded horns have width as the only variable (in order to get expected results). The trick in making horns work is folding them. Don't mess with that.

Sound though, since you're referring to ports, you're talking simplexx.
Seriously, so many different builders have built Bill's designs, and have been amazed.
That in itself should suggest don't mess with the plans...
Built:
DR 250: x 2 (melded array) with March 2012 plans. 2 more under way with CD horn
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

EduBH1978
Posts: 9
Joined: Tue Sep 04, 2018 3:12 pm

Re: Question about change in plans

#3 Post by EduBH1978 » Sun Sep 16, 2018 4:47 am

Grant Bunter wrote:
Sun Sep 16, 2018 3:59 am
Hi and welcome to the forum :)

Which plans are you talking about?

The folded horns have width as the only variable (in order to get expected results). The trick in making horns work is folding them. Don't mess with that.

Sound though, since you're referring to ports, you're talking simplexx.
Seriously, so many different builders have built Bill's designs, and have been amazed.
That in itself should suggest don't mess with the plans...
Yes, you're right, I shouldn't and I probably won't mess his plans.... What I really want is to compare his graphs with mines, since he probably measured the T/S parameters instead of using the data sheet of the drivers.
And I am.talking about the Simplexx 112!

ACUA
Posts: 348
Joined: Sun Sep 25, 2016 6:21 pm

Re: Question about change in plans

#4 Post by ACUA » Sun Sep 16, 2018 9:08 am

If you were to build the cabinet correct to plans/dimensions and then build a super thick shell around the thing only leaving the side that the ports and drivers exist on alone the thing would function correctly. Cabinet thickness can aid in structural integrity and resistance to resonance and the like but these loudspeaker designs are good and don’t need fine tuning. If you wish to change the port configuration for what ever reason you could, so long as you keep the important perimeters the same, vb, port tune port area etc. I am pretty good with designing my own bass reflex subwoofer enclosures and its my current understanding that Bill is clearly much higher on the engineering plain than I. That doesn’t mean he has a solution to everyone’s problem. If I want to build something that his plans don’t exactly fill than I attempt to design from the ground up. And usually for the money and pride of it I succeed well enough, I drink the coolaid here if I find a match in the speaker plans fit my needs/goals.. and yes the product is good but it is advanced compared to most other commercially available consumer products. You do need to know a thing or two to make the most of the products. Took me two years to feel comfortable here and that after 14 years of self teaching.
Advanced concepts underground audio

EduBH1978
Posts: 9
Joined: Tue Sep 04, 2018 3:12 pm

Re: Question about change in plans

#5 Post by EduBH1978 » Sun Sep 16, 2018 10:04 am

ACUA wrote:
Sun Sep 16, 2018 9:08 am
If you were to build the cabinet correct to plans/dimensions and then build a super thick shell around the thing only leaving the side that the ports and drivers exist on alone the thing would function correctly. Cabinet thickness can aid in structural integrity and resistance to resonance and the like but these loudspeaker designs are good and don’t need fine tuning. If you wish to change the port configuration for what ever reason you could, so long as you keep the important perimeters the same, vb, port tune port area etc. I am pretty good with designing my own bass reflex subwoofer enclosures and its my current understanding that Bill is clearly much higher on the engineering plain than I. That doesn’t mean he has a solution to everyone’s problem. If I want to build something that his plans don’t exactly fill than I attempt to design from the ground up. And usually for the money and pride of it I succeed well enough, I drink the coolaid here if I find a match in the speaker plans fit my needs/goals.. and yes the product is good but it is advanced compared to most other commercially available consumer products. You do need to know a thing or two to make the most of the products. Took me two years to feel comfortable here and that after 14 years of self teaching.
Thanks for your words! Yes , I'm trying to design from the ground, but I still don't have knowledge enough to know if it will work properly, since it's my first attempt, studying for it about a month. I don't know Simplexx tuning and VB, but guess I'll do if I buy the plains.... Then, I could use Bill's drivers data in my design and compare the simulations,
If there not much difference I'll know I'm in the right direction!

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Bill Fitzmaurice
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Re: Question about change in plans

#6 Post by Bill Fitzmaurice » Sun Sep 16, 2018 10:28 am

Using WinISD is only about 20% of the equation. 30% is knowing what you're trying to accomplish and why, 50% is translating that into an actual working design. You can learn how to use WinISD in a few weeks. The rest only comes with years or even decades of experience.

EduBH1978
Posts: 9
Joined: Tue Sep 04, 2018 3:12 pm

Re: Question about change in plans

#7 Post by EduBH1978 » Sun Sep 16, 2018 11:57 am

Bill Fitzmaurice wrote:
Sun Sep 16, 2018 10:28 am
Using WinISD is only about 20% of the equation. 30% is knowing what you're trying to accomplish and why, 50% is translating that into an actual working design. You can learn how to use WinISD in a few weeks. The rest only comes with years or even decades of experience.
In other words, I shouldn't expect similar results, since port tunings and vb are only minor part of the equation. I kindda know what I'm looking for, but I'm only in the first step of the hole path.

Thank you very much for your reply!

ACUA
Posts: 348
Joined: Sun Sep 25, 2016 6:21 pm

Re: Question about change in plans

#8 Post by ACUA » Sun Sep 16, 2018 1:50 pm

From my perspective, these bfm plans are all individually for a specific purpose, they address cost, weight, build ability, efficiency, application, the list goes on. The simplexx design is not as easy as just going to guitar center and buying off of their shelf. But they are considered the easiest plans Bill prescribes and they are good designs when you evaluate everything considered. Like I said for me unless one of Bill’s plans does not properly fit the need I will use his plans over my own attempts. Now you may want to design on your own something that sounds good I admire that attitude yes sir but I also see people at times my self included early on who can’t really engineer/design a really good loudspeaker on their own, but insist on devoting time to improving on his designs. Not exactly logical you know. With out the correct foundational knowledge and cognitive ability it’s a wild goose chase worse than Alice ever dreamed of. Stick around read the stuff from the archives 5 times or more it’s worth it. Build your own speakers and build these bfm speakers compare them it will make you better for it. I don’t benefit from posting here other than I enjoy it and I like the product produced here. I think you will to if your patient.
Advanced concepts underground audio

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