Thanks! Yes, though without the corner boards and had planned to mention bipolar loading along with dims if approved, so glad you added it to the layout.
GM
Hi.I decided to make a box just like this.Finally wife gave permittion about putting the drivers in front of the box.(i should paint speakers cone to white before putting them first for permittion,they were gray coloured)
Each driver has about 120cm2 Sd so i filled in the blank on web page as 240cm2 .
I have some questions
1) How important is the volume of the box for double 100w approx 87dB woofers? Can i have same bass amount if i reduce volume of box but line lenght will be the same?
2) I want to use long fiber wool for damping(I read it is the best damping material and it is plenty of available in our country).But my little daughter has an allergy to wool.Allergic sinusitis.Doctor forbid to use any of wool in house.Do you think she can be affected?(maybe mites can go out from hole of speaker)
3)I will make 80cm height box.(As many people told high qts drivers may be adjusted to lower than Fs.) Is it low height value for 0,67qts,50hz Fs woofer ? What can be ideal height for you?
4) My friend suggested TQWT instead of transmission line at same siz.What can be the differences?
Thank you for your suggestions.
Each driver has about 120cm2 Sd so i filled in the blank on web page as 240cm2 .
I have some questions
1) How important is the volume of the box for double 100w approx 87dB woofers? Can i have same bass amount if i reduce volume of box but line lenght will be the same?
2) I want to use long fiber wool for damping(I read it is the best damping material and it is plenty of available in our country).But my little daughter has an allergy to wool.Allergic sinusitis.Doctor forbid to use any of wool in house.Do you think she can be affected?(maybe mites can go out from hole of speaker)
3)I will make 80cm height box.(As many people told high qts drivers may be adjusted to lower than Fs.) Is it low height value for 0,67qts,50hz Fs woofer ? What can be ideal height for you?
4) My friend suggested TQWT instead of transmission line at same siz.What can be the differences?
Thank you for your suggestions.
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Wool (or felt) is very good but it is nothing sacred except to TL cult followers. You are fine by buying lots of pillow stuffing or the nice stuff from Parts Express (or equivalent) and the more you use the more you'll remove noxious peaks, esp higher up in freq. Just bag it in cheesecloth (or plastic window screening) and staple it (or hot glue) in place.
The recent discussion of adjustable "aperiodic" BR vents might be of interest to you as it is pretty much the same issues. The familiar shorty QWL - like BRs - has big "primary" resonance that most adherents don't want to compromise. But they do so at the cost of transmission of the higher, undesirable partials.
You'll find some REW measurements at:
17 foot pipe sub 12-230 Hz ±5dB
B.
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Keep in mind that the more stuffing used in a TL, in terms of stuffing density and/or stuffing length, in addition to smoothing out the response, you will also detrimentally affect the bass response, raising f3. Using a larger taper ratio, like 10:1 or more, and not locating the woofer(s) close to or at the beginning of the line, will automatically reduce/eliminate those unwanted dips in the response and require far less stuffing, thus allowing a deeper bass response.
Paul
Paul
For optimum results, the driver's center should be located in one of two places from the beginning of the line ; at or near 1/5 of the line's length or at or near 1/3 of the line's length (if there are two drivers, the midpoint between them would be the location of importance). An optimum taper ratio will be determined, along with the line's length, by the 1/4-wavelength resonant frequency appropriate for the driver's fS and Qts. You really need to model with accurate software in order to determine all of this, including stuffing density and location.
Paul
Paul
Yes, if you want to throw away a whole lot of pipe, you can follow the official rule and get a bit less of that noxious upper partial resonance. Works perfectly if you have undying faith in the precision of the dozen assumptions between buying the driver from a catalog and installing your TL in some spot chosen by family and other constraints in your own room.
Better to think in terms of how you'd like to sequester the rear wave and exiting it somewhere where it can mix-and-match with the front wave suitably for your room. In a few words: longest pipe you can make and lots of stuffing.
Long pipe to sequester rear wave
B.
Better to think in terms of how you'd like to sequester the rear wave and exiting it somewhere where it can mix-and-match with the front wave suitably for your room. In a few words: longest pipe you can make and lots of stuffing.
Long pipe to sequester rear wave
B.
Despite the impression some might gather from my little post, I have no problem with the Laws of Acoustics and, for sure, respect your in-depth experience.
If a person had a carefully measured T/S values and carefully built TL, then perhaps the anechoic (and maybe even the near-field) response could be predicted to the satisfaction of all, just as you say.
But as far as the path from catalog specs to arm-chair, that's a far longer chain. Anywhere but the most elaborate recording studios, the room's influence over-whelms (or at least whelms) all other influences, including basic resonance.
So the TL (or BR or most other boxes) will be unpredictable*.
B.
*Anybody fitted an eigentone app to their room and compared to their REW plot? And then moved their mic 30.48 cm? Maybe my tape measure is wonky when I measured the walls....
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Most diyers are using tools that pull values off the T/S curves that are not near as useful as the factory numbers and some of those tools are only making a vague estimation of the parameters as they are extrapolating values and not measuring them directly..
It certainly helps a whole lot knowing what you are doing, and we know that at the frequencies involved, the room DOMINATES. But the tools can add in at least a rudimentary room…
And you don’t get that experience without starting on the journey… it hust behooves our best interest if a diyers 1st project is a success — so they become addicted
dave
Hi.I have built only one tower with the parts that i cut myself with free thrown parts(mdf pieces that i cut with jigsaw are not very accurate) There are some blanks between the panels.Sorry for bad looking.
I listened to them with and without stuffing.
There is a huge difference with some polyester stuffing!Sound is much better with stuffing!
It was just for trying because of i am impatient for transmission line.I built TQWT with 5inch Aucharms in the past and liked it but i wanted to listen bigger dual drivers for bigger bass.
I know how to use winisd but I should learn using Hornresp too when i get some spare time.
TL Taper ratio is almost 1. (13cm a side and 12,5cm c side)
Do you think it will sound better with more expensive drivers?
I made TL a bit longer,80cm instead of 75cm.I thought i can use lower frequency drivers in future.It corresponds 47Hz though.
Eastech magnets are small( 7,5cm)
My aucharm Fullrange magnets are 10cm and it seems better quality built.
Eastech seems not very quality.
Some people say it is not worth to pay extra for subwoofer drivers.But i think it will make difference.
I listened to them with and without stuffing.
There is a huge difference with some polyester stuffing!Sound is much better with stuffing!
It was just for trying because of i am impatient for transmission line.I built TQWT with 5inch Aucharms in the past and liked it but i wanted to listen bigger dual drivers for bigger bass.
I know how to use winisd but I should learn using Hornresp too when i get some spare time.
TL Taper ratio is almost 1. (13cm a side and 12,5cm c side)
Do you think it will sound better with more expensive drivers?
I made TL a bit longer,80cm instead of 75cm.I thought i can use lower frequency drivers in future.It corresponds 47Hz though.
Eastech magnets are small( 7,5cm)
My aucharm Fullrange magnets are 10cm and it seems better quality built.
Eastech seems not very quality.
Some people say it is not worth to pay extra for subwoofer drivers.But i think it will make difference.
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FWIW, I modeled your line using Martin King's software. I'm pretty sure I understand the line's physical dimensions: 160 cm long with the driver's center located 30 cm from the line's beginning, a starting area (closed end) of 520 cm2 and an ending area (open end) of 120 cm2, smoothly tapered from beginning to end. I've attached a document showing two graphs of the predicted anechoic performance for an input of 2.83v/1m; the first graph for the line completely unstuffed and the second graph where the line is stuffed with polyester fiber in the first 2/3 of the line's length at a density of 0.75 lb/ft3, requiring a total of ~17.5 ounces of fiber (~500 grams if my conversion is correct). The stuffing density and length is typical of what I use for tapered lines, and it isn't necessarily the "best" in all cases.
Paul
Paul
Thanks, Dave, for making what I modeled more readily accessible. I want to add a few more details. Without any stuffing in the line, the system tuning frequency is ~36 Hz, but with it added as I modeled, it decreases to ~33 Hz. Also, an input of 15w/1m is about all I'd consider as a safe, continuous input; the output SPL increases to an average of 98 dB, compared to 89 DB for the input of 2.83v/1m, and the driver's excursion doesn't exceed Xmax until about 30 Hz.
Paul
Paul
Hi.Do you think it is the best ratio for these drivers ?I made some simulations but i could not decide.Wife does not accept doing trial anymore. I should build final speakers it asap.With rapid glue and spray and and 45degree angle cut.It also makes box cheaper.White coloured mdf also does not need painting by this way
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