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1995Tercel

EXPERTS ONLY PLEASE Building the perfect transmission line box, many questions

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On 11/8/2018 at 4:00 PM, hispls said:

Do download and figure out how to use hornresp software.  EVERYBODY I have ever seen trying to build any type of horn, bin, or quarter wave box uses it. 

You can safely say you'll lose an inch from the diameter of the driver for surround, that should get you close enough.  Speaking of close enough if you're off on an end 3hz change in tuning of a box is inaudible in my experience and even 5hz is barely audible so don't drive yourself crazy there.

According to that source the unwanted high resonances that you think you want to tame with stuffing are only an issue in full range system so you should not need any batting unless you're trying to cheat a shorter line and from my experience with stuffing in general while you can change response slightly you pay for it with efficiency.

I do not believe you need a chamber for a true transmission line, that becomes more of a horn or just a ported box.  AFAIK true T-line is the woofer firing into the line which is consistent length throughout.  Having an odd size chamber puts you more into horn territory, though I suspect the hornresp software will have options where you can play with that.

Lastly I think if you want to play down to 20hz you will not be able to build this without a bend.   You are getting into a LONG wavelength, and that said I'm not sure how far below FS you can go with a t-line.   There have only been a handful of guys on this forum who have built these so if you want better, do a forum search and see who has done them, PM those guys and hope they're still active.  Good luck and please post a build log as you go.  I've heard one proper T line in person and it sounded very nice.   Almost worth the space and the wood.   Mind you, with today's EQ options and how cheap power is and how robust our woofers are there's no reason you can't get flat from 20-80hz in the same space a few different ways these days.   I'd consider T-line not something you "have to have" in order to get a particular sound but just an alternative as something to do if you like a good DIY woodworking challenge and interesting conversation piece.

Good luck and please post a build log here.

Thank you for your response. I downloaded hornresp, there is a learning curve to say the least.

 

The batting wont help with any of the harmonics below a certain Hz? Even thought my sub box will have a low pass filter (i think thats what it's called) won't it still produce multiples of the 39hz Fs that are problematic?

I am currently trying to find a woodworking shop (or audio shop) that will rent me their space on the weekend to work on the box, still no concrete dimentions. I'll try to document my progress once I start.

14 hours ago, Boomin_tahoe said:

I'm currently running a T-line tuned to 34Hz. Will play down to 28Hz and upwards of 90Hz. It's a very bandwidth enclosure. Sub is a DC Audio m3 8

So would your box be a modified horn, because it has the chamber behind the sub? From my elementary understanding, doesnt the parallel wall directly behind the sub load it with air and create many resonances? Beautiful finish on that box, what kind of wood/stain/sealant/wax? What's the box underneath the subs? Mid drivers in an enclosure?

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23 minutes ago, 1995Tercel said:

Thank you for your response. I downloaded hornresp, there is a learning curve to say the least. 

Yep.  Definitely not as simple or user friendly as WinISD or other simple box design software.  Other forums have guys that really geek out on it though so you should be able to find answers with google.

25 minutes ago, 1995Tercel said:

The batting wont help with any of the harmonics below a certain Hz?

It's the higher stuff that becomes an issue, but that's really only true (audibly) if you're, for example, using Fostex 7" full range (popular for various exotic horn type boxes)to try to make some bookshelfs where your total power is a 40WX2 tube am and you wind up with issues at audible levels at the higher multiples fighting with your midrange.  Safe to say with what we do in a car and a true subwoofer any of that higher stuff could be ignored.    Batting probably won't hurt but we simply don't see it used in cars.

 

35 minutes ago, 1995Tercel said:

I am currently trying to find a woodworking shop (or audio shop) that will rent me their space on the weekend

 

I'd think for liability reasons you won't get anybody to bite unless you're close personal friends with someone there.  Better bet might be to finalize a cut-sheet and ask a cabinet shop how much to cut those pieces.    

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12 hours ago, Popwarhomie said:

 

Who would PM you asking for your help?

 

You run stock electrical.

You have never built a box

You couldn't re glue a subwoofer surround. 

You run coaxial door speakers off headunit power.

You keep giving advise to things you have ZERO experience with.

 

You are a stay at home mom who smokes 4 packs a day yet complains about not being able to afford anything and yet your english and grammar is still horrible.

 

mom? i'm 51 mom died 15 yrs ago

 

 

 


KENWOOD X301 HU, PRECISION POWER Phantom 1000, FU 750 12, 2.1cfad ported, soundqubed 6.5" coax/doors, hp & lp xover on hu, AGM starting batt...

Boomin_tahoe said:
2 ohms rule

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6 hours ago, hispls said:

Yep.  Definitely not as simple or user friendly as WinISD or other simple box design software.  Other forums have guys that really geek out on it though so you should be able to find answers with google.

It's the higher stuff that becomes an issue, but that's really only true (audibly) if you're, for example, using Fostex 7" full range (popular for various exotic horn type boxes)to try to make some bookshelfs where your total power is a 40WX2 tube am and you wind up with issues at audible levels at the higher multiples fighting with your midrange.  Safe to say with what we do in a car and a true subwoofer any of that higher stuff could be ignored.    Batting probably won't hurt but we simply don't see it used in cars.

I'd think for liability reasons you won't get anybody to bite unless you're close personal friends with someone there.  Better bet might be to finalize a cut-sheet and ask a cabinet shop how much to cut those pieces.    

Yeah I definitely have to look up what all the abbreviations mean. Almost none of them match the units on the Sundown Spec sheet for the sub.

 

Ah makes sense. I'll try to keep this project simple.

 

By cabinet shop, do you literally mean kitchen cabinet place? Would I supply the wood?

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11 hours ago, 1995Tercel said:

Thank you for your response. I downloaded hornresp, there is a learning curve to say the least.

 

The batting wont help with any of the harmonics below a certain Hz? Even thought my sub box will have a low pass filter (i think thats what it's called) won't it still produce multiples of the 39hz Fs that are problematic?

I am currently trying to find a woodworking shop (or audio shop) that will rent me their space on the weekend to work on the box, still no concrete dimentions. I'll try to document my progress once I start.

So would your box be a modified horn, because it has the chamber behind the sub? From my elementary understanding, doesnt the parallel wall directly behind the sub load it with air and create many resonances? Beautiful finish on that box, what kind of wood/stain/sealant/wax? What's the box underneath the subs? Mid drivers in an enclosure?

No. It's still a T-line. That chamber you see is just a void area that needed to be filled to get the correct "volume" and maintain the necessary width/length for the super long port. I used a stain from Lowes called English Chestnut. Something not too light or too dark of a finish but in between. Once applied, it's the polyutherane that really brings out the shine and colorness of the stain. That "box" under my enclosure is where my amp is...

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97 4 dr. Tahoe

Interstate battery

Alpine 9835

Polk Audio MM6501 comps

Wolfram amps coming soon, 3000.1, 125.4

2 Sundown Audio X 15's Tuned @ 30Hz.

Knukonceptz/Royal Excelene wiring

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20 hours ago, Popwarhomie said:

 

Who would PM you asking for your help?

 

You run stock electrical.

You have never built a box

You couldn't re glue a subwoofer surround. 

You run coaxial door speakers off headunit power.

You keep giving advise to things you have ZERO experience with.

 

You are a stay at home mom who smokes 4 packs a day yet complains about not being able to afford anything and yet your english and grammar is still horrible.

 

20 hours ago, Popwarhomie said:

 

 

 

 

Are you on FB at times?

 


97 4 dr. Tahoe

Interstate battery

Alpine 9835

Polk Audio MM6501 comps

Wolfram amps coming soon, 3000.1, 125.4

2 Sundown Audio X 15's Tuned @ 30Hz.

Knukonceptz/Royal Excelene wiring

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4 hours ago, 1995Tercel said:

 By cabinet shop, do you literally mean kitchen cabinet place? Would I supply the wood?

Yes.  Any shop that builds custom cabinets for homes should be able to make perfect cuts and deal with pieces about the size of what you'll want.  They may or may not use MDF, do not use particle board unless you plan to coat it with resin (which you probably wouldn't for this project).  Any decent 3/4 ply should do the job too.

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11 hours ago, Boomin_tahoe said:

 

Are you on FB at times?

 

Yep. Always trolling facebook.


2016 Focus ST3 - Rockford DSR1 / PPI 900.4 / Silverflute 6.5" mids / Massive CT2 tweeters /Sundown Xv2 15"/ Taramps DSP3k / Stinger Roadkill / KNU wiring / Northstar SMSAGM80 /

2010 Focus coupe 157@46hz

Pioneer 80prs /(8) FU Audio 750 12"s / (4) FSD 2600s / (1) FSD 125.4 / (1) FSD 85.4 / (4) Crescendo UN-10" mids / (4) Crescendo FT1 tweeters / Stinger Roadkill / 2/0 EB flex wire / (5) Powerware 90AH batteries / DC 270XP Alt /

https://www.youtube.com/popwarhomie

too many freq at once, burn the coil, we all know, over 40-50hz, its all coilburning material.

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