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Old 31st January 2012, 12:31 AM   #21
kctess5 is offline kctess5  United States
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Quote:
I also suggest you to place the terminating port facing the rear side of the sofa,that will be near a corner and the enclosure will be shaped like an L with a constant rectangular CSA = (2* wood +driver frame width) * X; X = (S1/dfw+S4/dfw+3*wood) where S1 is the larger area and S4 the terminating area.

The total internal length is 290cm that when folded once will be just 145 cm=
~57.087"+2x wood, thus the gross volume is~ CSA*L.

The folding expansion is Par = parabolic opposed to conical as shown in the HR program.

You can when *Exporting* the CSA from HR choose an arbitrarily section length to reflect your intentions.

You really need to consult the HR built in Help facility.
Once again thanks for your help!

I must say I'm a bit confused though, will my design work as is or do you think I should change it? If so what should it look like, what should the taper be, what should the cross sectional area be, how long should it be (sorry for a lot of questions)?

My design is just under 10' long, almost exactly the 290cm you suggested, the CSA is 150 sq in (approx, +/- 10ish) with no taper (i.e. constant csa).

I prefer to go with the straight TL with no taper rather than an expanding horn for ease of design, build, fitting into that shape etc

I don't know if I mentioned this but everything must be on the front panel because it will almost be touching the wall on the other 3 sides, my design has the drivers, port, and amp all on the front. I played around with a bunch of fold schemes but this was the only promising one, also the max width is 4'

I prefer to have two drivers rather than one for vibrations and things like that which I mentioned earlier

Quote:
Yes, IME you will not notice the bass emitting when your sitting on your sofa but instead from your main speakers wherever they are located if using a 24 dB LPF.
This is exactly what I was thinking! Ive got an active crossover so I can mess around with it to whatever measures the best in room

Btw the reason I'm not using hornresp myself is first of all because I have a mac and second of all because I have absolutely no idea how to.

The attachment dimensions are not exactly right, they were pretty arbitrary at the time I made the model. Refer to what I said earlier about the length and cross sectional area and the attachment for the general shape, keep in mind that this shape was optimized for 2 drivers

Sorry for being a bit slow, I've only been doing this a few months and I'm in highschool... hence budget restrictions
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Old 17th February 2012, 04:49 PM   #22
kctess5 is offline kctess5  United States
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Default Build

Two days ago I found a way to get onto HornResp, after a bit of a learning curve I figured it out, mostly. I came up with a very promising design that modeled quite well and called it a night. Yesterday during school I tried to fold it (very tedious) and near the end I realized it wouldn't fit. I made a few minor adjustments without hornresp hoping it would be close enough and managed to get all the dimensions. When I got home I modeled it and with one or two very minor adjustments I decided it was good to go.

I finally got a chance after school to go to home depot an get some MDF and start cutting. I started by drawing the 1:1 scale detailed drawings on the bottom piece of MDF, taking into account the 3/4 thickness and converting everything to the nearest 16th.

After some very precise cuts I got to the point where I'm at now. I laid it all on top of the bottom sheet on top of the drawing. I have not yet glued and screwed those on but thats going to happen today.

My dad thought it was really cool, he's done a a lot of building stuff also (the tools I use are his) so he was pretty impressed with the geometry and how precise my cuts were. My mom on the other hand is happy that the drivers haven't arrived yet (backordered from parts express hopefully arriving at the end of the month)

At some point soon I'll post all of the hornresp information and the detailed dimensions I drew for anyone who likes the design in the spirit of open source.

Does anyone have any suggestions for putting the top on? I need to make sure that the screws actually go into the vertical pieces but I won't be able to see them. I was thinking about putting glue on the top of the vertical pieces and very carefully lining the top piece up then lowering it down. Then I would quickly take it back off and drill through the top where ever there was glue, lower it back where it was and screw through those holes, then hit it with the nail gun in between the screws. Alternatively I could measure everything but That may not be as acurate
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Old 17th February 2012, 05:49 PM   #23
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Your glue idea would work, but is messy, believe me, I have done it that way and regretted it.

You could tape wrapping paper (or tape together newspaper) to the sides of the cabinet, then run a carpenter's pencil lightly sideways to outline the boards, then transfer the paper to the cover and use it for a template for screwing.

Last edited by weltersys; 17th February 2012 at 05:51 PM.
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Old 17th February 2012, 06:09 PM   #24
kctess5 is offline kctess5  United States
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I like that idea. I could get some white butchers paper from my school and use that. It would go faster too cause I could just use the pneunatic nail gun with a million nails.

I just got a gallon of glue so I'm set. I also got a piece of sonotube that I'm going to cut up and put in the corners to minimize reflections. We've got some caulk left over and I'm going to seal this puppy up
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Old 21st February 2012, 03:53 AM   #25
kctess5 is offline kctess5  United States
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Default The saga continues...

This weekend I got two days in working on the sub and I got as far as I can without my woofers or stuffing.

I need to go to my cabin where I have a a large amount of soundproofing material that I'm going to use for stuffing (I need a lot and I don't want to have to buy that much)

The drivers are set to be in to parts express on the 28th so I should get them around the 4th of next month.

The build went pretty smoothly, no big problems arose though keeping everything accurate and according to my design was tricky.

The sub right now is in three pieces, when its all done it will be in two pieces. The back/armrest are one piece that gets bolted to the top of the subwoofer enclosure. I did this to make it easier to take upstairs and work on it in the future.

I finished it with some cheap black fabric and put a large cushion to top of it. The grill is held in place with some neodymium I had, mostly its to keep my cat out of the maze but also to make it not recognizable as a subwoofer.

It barely fit in place, theres probably only one or two millimeters of clearance.

This thing is incredibly heavy, it weighs around 200 lb as it is now, with two woofers its going to be a bit heavier

The stand for my electronics is going to change soon. I am going to get rid of that sub in a few weeks for obvious reasons, I'm using its plate amp and stealing its driver for later use. I'm going to extend the flexy down to the floor and build a special shelf for the laptop thats big enough for its screen to be up and a peltier cooler rack to keep its fan from coming on (very annoying with hulu). Also I'm going to extend the rear piece of allthread up and mount the screen on it so it can be adjustable and rotate the screen.
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Last edited by kctess5; 21st February 2012 at 04:00 AM.
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Old 28th February 2012, 04:34 PM   #26
kctess5 is offline kctess5  United States
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I got the drivers yesterday and dropped them into place. I cant close it up yet because i don't have the stuffing or the time. Even though it wasn't sealed I must say when I sat on it and tested it it sounded pretty great. I can't wait to seal it and get the drivers all broken in.

I'm not really sure what to do about stuffing it. I have a bunch of sound proofing material at my cabin but were not going for a few weeks. Is it worth the wait for that? Would i line all of the inside walls with it or just part?

If theres something better (and cheap!) What would it be? Usually I use batting but I don't really want to pay $25 for that when i have some other stuff for free. What about in wall insulation? I imagine that's pretty cheap.

Im having a hard time finding the norm as far as stuffing goes for where to put it and how much. I've seen that .5lb/ft^3 is pretty standard.

Any help appreciated thanks!

Last edited by kctess5; 28th February 2012 at 04:36 PM.
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Old 29th February 2012, 01:24 AM   #27
bjorno is offline bjorno  Sweden
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Hi kctess5,

In post21 you wrote:

Quote:
...My design is just under 10' long, almost exactly the 290cm you suggested, the CSA is 150 sq in (approx, +/- 10ish) with no taper (i.e. constant csa)..I prefer to go with the straight TL with no taper rather than an expanding horn for ease of design, build, fitting into that shape etc...
Sorry for missing this question, See the submitted OD-TL sim of your changes from my T-TQWT into your OD-TL using two drivers:

Looking at the FR and the fact that you have designed a multi-folded path to the terminus the HR OD-TL sim. is not reliable when entering stuffing(using multiple folds too) into the equations.

Stuffing by taste is not recommended as SPL could be lost unnecessarily as the damping material density profile might not optimal.

The lower peak seen in the HR sim will not cause problem and should disappear due to the foldings but the peak at 90Hz should be lowered a bit but the upcoming peak at ~200Hz to a greater degree.

Quote:
Originally Posted by kctess5 View Post
..I can't wait to seal it and get the drivers all broken in..
You've done a great job so far with this sofa TL but now you need IMO slow down a bit because of the complex airways:

The entire outline needs to be traced down by making a list of all used CSA:s and section length's.

Then if simulated in an appropriate program the localization of the damping material / different stuffing density and weights can be determined.

Quote:
.. Is it worth the wait for that? Would i line all of the inside walls with it or just part?..
To being with,I would do that: I.e. spray gluing a 1/4"-1/2 felt at least 2/3 of the length but only stuff precisely as much as needed per built section down to the very last bend. IME:The needed weight of stuffing will then be minimized and not visible if looking into the terminus.

Quote:
What about in wall insulation? I imagine that's pretty cheap.
Very effective if mineral wool based but a disaster for your health, so ruled out and not recommended as micro size particles could be emitted into the room.
But if used : Leave at least 25% of air-columns to be formed between the mineral wool battens(~2 thick) and do not use any stuffing to fill/shut the open airways up as the attenuation when using mineral wool is by far more effective than any normal speaker stuffing material.

Quote:
..Im having a hard time finding the norm as far as stuffing goes for where to put it and how much. I've seen that .5lb/ft^3 is pretty standard..
There is no norms but an density interval to use: Typically a span of~0.1-0.5lb/ft^3 that is mostly used. 0.5lb/ft^3 or even up to 1 0.5lb/ft^3 is about standard for a traditional totally filled TL but could be to much if followed in your case:

Be patient and post a list containing all CSA: and section lengths. If you want a hint from me you have to list(calculate all) the CSA:s in terms of the Driver Sd area.

( Section area (cm^2)/ Sd(cm^2) = Decimal Number.

The section lengths should be listed in inches. See your photo where I doodled hints on where to measure the required section lengths and CSA:s.

When this is done all the data could be entered into MJK:s most advanced program(tedious work but IMO very rewarding if done and wort waiting for ) and the return would be the weight of stuffing material using a certain density to be filled in between (per section) the (sometimes different) CSA:s enclosing volumes.

It must also be clear that the driver(s) you are using have T/S that are close to whats earlier was given. I give no guarantee for any posted calculations if the T/S are far off.

b
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Old 29th February 2012, 02:24 AM   #28
kctess5 is offline kctess5  United States
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I actually have a plan with the exact dimensions on paper. I'll take a picture and post it. It may be a bit hard to read, let me know if you can't see a dimension. I spent about 2 hours on this getting the taper right and I built the sub quite accurately after it. I would say the accuracy on all of the dimensions is +/- .0625 inches, for the lengths, all of the widths are more exact than that. Is there any reason for me to measure everything if I'm quite certain its the same as the plans?

I need to fire up the jet engine (my pc laptop with an incredibly loud fan) and take screen shots of the models that correspond to the plans, it actually from memory is flatter and lower than that model you just posted, ill post it sometime tonight

Also I don't have that software and have no idea how to use it, also isn't it not free?
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Old 29th February 2012, 05:15 AM   #29
bjorno is offline bjorno  Sweden
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First I must make a small revision of my last posting:

Quote:
peak at ~200Hz
:

Should read: peak at ~145Hz. Then the label TH at the posted screen-shot of HR main screen should be read OD instead.

Quote:
Originally Posted by kctess5 View Post
I actually have a plan with the exact dimensions on paper. I'll take a picture and post it. It may be a bit hard to read, let me know if you can't see a dimension..
If I had your speaker in front of me, I would take the measurements needed in sequence and enter all into MJK:s program but as I don't have access to your sofa, only my own and it's difficult to read your numbers in your last picture where I also immediately noticed quite a few vital numbers were missing, I would normally and move on to another thread and...

Unless a complete list of the numbers(or a complete drawing with printed numberings) I,m asking for( Some must be DIY calculated) I see no reason to spend my time of something that would meet a dead end after say half an hour sojourn with MJK:s program.

Quote:
I spent about 2 hours on this getting the taper right and I built the sub quite accurately after it. I would say the accuracy on all of the dimensions is +/- .0625 inches, for the lengths, all of the widths are more exact than that. Is there any reason for me to measure everything if I'm quite certain its the same as the plans?
Thats only the coffee brake time taken for a true DIY'r, he will if necessary spend a whole day to get it right (I don't think it matter if you built the sub with an accuracy or 0.4” of every dimensions) but you have to understand here, that all ...measured... sections/ CSA:s is what counts, not the accuracy, they must be entered correctly in order to ..reflect.. your sofa-sub air-ways.

I counted 22 CSA:s and I wont accept an area/section presentation other than what I'm earlier asked for,you have to do the required number-crunching too.

Quote:
I need to fire up the jet engine (my pc laptop with an incredibly loud fan) and take screen shots of the models that correspond to the plans, it actually from memory is flatter and lower than that model you just posted, ill post it sometime tonight
Much appreciated if you take my requirement seriously! If your model is in reality flatter and lower. It would for sure affect the required numbers I,m asking for.

Quote:
Also I don't have that software and have no idea how to use it, also isn't it not free?
It's not free but IMO very affordable.

b

Last edited by bjorno; 29th February 2012 at 05:32 AM.
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Old 29th February 2012, 06:34 AM   #30
kctess5 is offline kctess5  United States
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Ok I'll take all the measurements and post the sims as soon as I can. Sorry I didnt have time to get the other computer out tonight. Time is something I don't have a lot of between all of my AP classes and pole vault and everything else I have going on.

Thanks for your time! I'm sorry if I'm frustrating you at all

Quote:
Thats only the coffee brake time taken for a true DIY'r, he will if necessary spend a whole day to get it right
That was just the time I spent folding the thing once I knew the taper. I spent another 3-4 hours getting the models right and tweaking them for my real world constraints

Luckily tomorrow I have my engineering class and assuming it goes like usual I should be able to model the thing on inventor and get some really detailed drawings with all of the cross sections and lengths annotated
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