W8-740Q: what am I doing wrong? - diyAudio
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Old 30th July 2014, 05:00 PM   #1
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Default W8-740Q: what am I doing wrong?

Alright,

I got a pair of those Tang Band to play with.

I wanted to build a folded horn for. Them, but I still have to understand Hornresp software.

In the mean time, I fired up Winisd and to my surprise, it gave me a 6 litres box. Now, I'm not even sure I can fit this driver in a 6 l box!

What am I doing wrong here?
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Old 30th July 2014, 07:36 PM   #2
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Well, you're not doing anything wrong! The low Qts (0,28) and Vas (15,69L) will result in a rather small (adviced) box. Making such small box might be do-able.

But if you want to port it you'll have a bigger challenge. Because a reasonably low tuned port will be (relatively) large with such a small box.

I'm having a hard time getting a reasonable response with this driver hornloaded in hornresp btw, but that was just a quick check.
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Old 30th July 2014, 07:52 PM   #3
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by perceval View Post
Alright,

I got a pair of those Tang Band to play with.

I wanted to build a folded horn for. Them, but I still have to understand Hornresp software.

In the mean time, I fired up Winisd and to my surprise, it gave me a 6 litres box. Now, I'm not even sure I can fit this driver in a 6 l box!

What am I doing wrong here?
What is your size constraint and how low of bass extension do you want. It may be doable with a PPSL bandpass box where the vent wraps along the inside wall with a fold. It should work for horn loading too but need size constraint and low freq you want.
I am guessing you are OK with a 3 cu ft box and would like 30 Hz?
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Old 31st July 2014, 01:45 AM   #4
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Ok, good to know that I was not going crazy!

I could build an enclosure that small just to burn them in for a while, until I have my horn loaded done.

3 cuft gives me the rough sizing of 12"W x 18"D x 24"H. That's very doable.

I know how to input data into Hornresp, that's of course the easy part, but I don't know how to use the resulting calculations to design a folded horn.

I've looked for tutorials on the net and youtube, but I can't find anything that will give me the basics by example. Most tutorials assume knowledge of Hornresp!
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Old 31st July 2014, 05:44 AM   #5
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I've been playing with Hornresp a bit.

Tried to open the Help file, but Windows 8 told me it cannot open that file, missing something....

So, I went to the designer part of Hornresp, played with the sliders, trying to understand what the sections are and such,...and this is the only way I could get a flatter line... but looking at the numbers, I believe that makes no sense!
Attached Images
File Type: png hornresp.PNG (53.8 KB, 157 views)
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Old 31st July 2014, 06:25 AM   #6
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Wow that is huge, for an 8" correct?
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Old 31st July 2014, 08:13 AM   #7
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I've been learning more.

Basically took one of Bjorno's post and studied it a bit.
Oh, and found that the help file is opened from the program directly, not from double clicking on the file itself. That's going to help me even more!

To keep the build simple, I saw that S1, S2 and S3 are the same width. Playing with driver's placement to get a reasonable line and then, trying to flatten the line with some EQ.
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Old 31st July 2014, 01:31 PM   #8
GM is offline GM  United States
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This spreadsheet may help: Easy Horn Excel Spreadsheet

GM
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Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
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Old 31st July 2014, 01:40 PM   #9
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There are a few things wrong with the attached pic. idk if you have changed the chamber size (Vrc) in the wizard, but you should have a chamber if you're aiming for a FLH. Also input the Lrc (length of the rear chamber) Vtc (volume throat chamber) and make Atc the same as SD. Also, you made S3 9cm^2, that will basically be closed.

Understanding al the inputs and some common sense will help a lot. Hovering over the inputs will show you what they mean. Also model in Par instead of Con. An easy build will be using only 1 section of Par.

Perhaps you could tell us what u want your subwoofer to do? (max size? how low? aiming for sensitivity? do you have dsp for corrections?) A folded horn may not be suitable for your driver or application. Perhaps a ppsl (or something else) will work a lot better.
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Old 31st July 2014, 02:05 PM   #10
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GM, I had a look at the spreadsheet, but again, a bunch of numbers which assumes I know what I am doing there. I learn by hands on experience, I need to see and feel it.

My ideal box would be about 12"W x 18"D x 24"H... could get taller if needed.

30ish Hz is fine by me. Wife would kill me if we had earth shaking low frequency (we get that from real earthquakes, but they usually do not match up with the soundtrack!) ... that's why I chose those 8" which were highly recommended.

I made a second try at Hornresp and like I mentioned, looking at Bjorno's posts, I started to understand a few things. I still don't know how to calculate the bends and turns if I want the enclosure to be anything else than a very tall box.

I don't even understand what the green and red circles are. My guess is the drivers position, green is front and red is back, right?

Maybe I could draw the resulting picture in Illustrator and fold it in there, keeping the width and the length.
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