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It is currently 23 Sep 2019, 05:16

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PostPosted: 14 Sep 2019, 22:45 
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Joined: 28 Dec 2010, 22:07
Posts: 349
Disclaimer - before you all start, I know there is a process for designing a ported box. I also know this process involves purchasing drivers with known parameters. I'm working with a set of drivers I already have so telling me to purchase X or Y isn't going to be helpful.

Having said that, I have these drivers...

(https://www.amazon.com/DS18-SLC-N4X-Coaxial-Speaker-Undiscovered/dp/B01GDZMUQM/ref=sr_1_10?keywords=4%2Binch%2Bspeakers&qid=1568518080&s=gateway&sr=8-10&th=1)

I want to make wood enclosures for them, and I'm looking at vertical towers for a form factor...

https://i.ytimg.com/vi/RM_bcZnECEs/maxresdefault.jpg

I'm toying with the idea of porting the speaker to extend my bass response. As speakers that are 4" in diameter, they won't have a stellar low-end (quoted at 100 Hz). However, I don't have T/S parameters and only know that the sensitivity of the speakers isn't great (82.4 dB/w).

So...am I largely mistaken or could I get reasonable results by trying something? I'm thinking of using some plastic pipe to make a rear-firing port at the bottom. If the interior dimensions of the tower are something like 6" square by 15" high, I would have a little room to play with. It would be helpful to find an online calculator that would help me figure the dimensions of the box and the correct port size to use, but bear in mind I don't have T/S parameters and I won't likely get them.

I'm going to make the enclosures for these anyway, but I'm considering the possibility of playing with a reflex port. Maybe someone can help me figure this out.

Ed

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PostPosted: 15 Sep 2019, 21:48 
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Joined: 23 Feb 2017, 02:02
Posts: 546
By doing trial and error and measuring the actuall frequency response over the range, you can fine tune the thing without knowing the parameters
anything below 89db sensitivty is not worth having. Need to juice way too much power to get babie sound volumes.


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PostPosted: 15 Sep 2019, 22:16 
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Joined: 28 Dec 2010, 22:07
Posts: 349
ILoveHiFi wrote:
By doing trial and error and measuring the actuall frequency response over the range, you can fine tune the thing without knowing the parameters
anything below 89db sensitivty is not worth having. Need to juice way too much power to get babie sound volumes.


That's what I had planned to do. I am going to see if there's any better way of doing it than just making random stabs in the dark. Thus, I'll be reading a lot before I get started.

ILoveHiFi wrote:
anything below 89db sensitivty is not worth having. Need to juice way too much power to get babie sound volumes.


I disagree with that. Sensitivity is good to have, but a lot of speakers have less than 89 dB/w. High sensitivity speakers are needed when you use tube amplifiers with only 1-2 watts of total power. Even with cheaper speakers, 5 watts sounds loud enough to fill the entire first floor of my house. Keep in mind that our ears would perceive 50 watts as only twice as loud in the same speaker.

Take the HiVi B4N, a popular speaker for DIY builds (link below). Its sensitivity is listed at 85 dB/w. That doesn't stop people from using it to make good bookshelf speakers and other builds. Often, since tweeters have higher sensitivity, builders make attenuation networks to lower the power at the higher frequencies, so that the output power from both drivers is equal.

[url]parts-express.com/hivi-b4n-4-aluminum-round-frame-midbass--297-429[/url]

It's nice to have 90 dB/w speakers and up, but most people aren't willing to spend several hundred on their builds. Let those who would have at it. I'm wanting to experiment with these because I have them.

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PostPosted: 15 Sep 2019, 22:43 
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Joined: 23 Feb 2017, 02:02
Posts: 546
The 902.512uk drivers 101db and 15inch cost me only 58USD from a local store
From element 14 if you buy enough money for free shipping, then some 8 inch full rage arround 89-92dB cost only 13USD each.


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PostPosted: 16 Sep 2019, 11:17 
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Joined: 11 Aug 2016, 02:03
Posts: 41
Location: Bulgaria
BowToEd- "I disagree with that. Sensitivity is good to have, but a lot of speakers have less than 89 dB/w. "

Correct!
There is so much information on the net, but efforts must be made to find it ...

I


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