design of dalines (transmission lines)

[kneadle]

Originally posted by Dave Jones


As I've said before, the Mathcad 8 demo will not work on my machine. (No, I don't run a virus scanner.)

Do you need help troubleshooting your system? Do you know what might be causing this difficulty? I'd be glad to help.

Dave

[Dave Jones]

Originally posted by kneadle



Do you need help troubleshooting your system? Do you know what might be causing this difficulty? I'd be glad to help.

Dave

Not a clue. When I open Dr. King's file, nothing appears to happen. It also does not refresh properly, and sometimes crashes. I really don't have a lot of time to look into it.

[Dave Jones]

Originally posted by GM
Well, if the demo won't work then neither will the 'real deal', and since no other program except possibly Hornresp or equal can't sim a Daline/TL, you're SOL unless others will take the time.

If you can read MS Word docs I can send you a cut n' paste of the sim I did of the Focal Daline done 'my way' to give you an idea of what to expect. I can send one for the little JX92S pipe also.

GM

That's very kind of you. I would love to see them. My email address is djones (at) innovativeroboticsNSPM (dot) com. Replace the (at) with @ and (dot) with a period and remove "NSPM". (Dag nab spammers crawl the web for email addresses.)

Actually, I'm off on another tack now. I was interested in dalines because I thought I could design the box in the shape I want, to wit, tall and shallow. What I would really love to see is a sim of the response from this system:

JX92S driver
straight tube, closed on one end, completely open on the other

height 48"
cross sectional area 35sq.in. (Perhaps 3.5" by 10")
damping, Poly fiber 1.65 lb per sq foot, completely filling the tube

[BAM]

I, however, am interested in continuing this discussion about Dalines. I have a design for a daline that uses two of the famous Parts Express "NSB" 4" wide-range drivers, which cover the range from 75 to 15,000 Hz, and a mylar semi-dome supertweeter. The discussion began in this thread:

Just for the sake of asking... (about Bass)

Based on what kelticwizard said:

Actually, Bam, your Qtc in the box is going to unaffected by the box volume much. So your Qtc ought to be close to the Qts of your NSB, wihich is 0.79. Tha Qtc for the top chamber of the System IV was 0.83,(very close), so you should be right on.

Also, Steve's Fs of the Bandor driver was 65 Hz. The Fc of his top chamber, (if it were sealed), would be around 97 Hz. Your Fc should be about 105 Hz, which is your Fs.

My guess would be to make a port, (Line) that is 56 inches long, (1/4 wave of 60 Hz), that tunes the line to 40 Hz. That would be my guesstimate.

Don't get nasty if comes out lousy. I am just trying to figure out by suppositions here.

Remember, the wavelength of 1 Hz = 13,500 inches. To find the Quarter Wavelength of 60 Hz, we go:

13,500 in ÷ 60 Hz ÷ 4 = 56.25 inches.

With that in mind, I came up with the following design, and I want you to take a look at it and see if you notice any problems. I would check it myself with the Mathcad worksheets, but I can't figure out how to use them beyond changing the T/S parameters, line length, and line dimensions. I see no provision anywhere for modeling the top chamber.

I have some drawings that I made of what the design would look like, and I will post them here in a few minutes.

[BAM]

Here is a picture of what the front, side, and interior of the design will look like.

[BAM]

By the way, I will be gone next week (just on the off chance that someone replies and sees that I am not here to answer and thinks that I have given up on the design.)

And yes, that thing is just slightly over four feet tall...

[Dave Jones]

Originally posted by BAM
By the way, I will be gone next week (just on the off chance that someone replies and sees that I am not here to answer and thinks that I have given up on the design.)

And yes, that thing is just slightly over four feet tall...

So... Fs = 65Hz, Qts=0.79. What is Vas?

[jackinnj]

here's a new link:
http://www.tech-diy.com/daline.htm

[planet10]

Originally posted by jackinnj
here's a new link:

It is interesting, that the B110 XO has what look like a BSC & Zobel networks

dave

[BAM]

No, 65Hz is not Fs in the NSB dalines. The drivers' Fs is 105 Hz, but its stated frequency response goes down to 75 Hz. 65Hz is the line tuning point. That is, the line is a quarter-wavelength of 65 Hz. The line being tuned to that point takes advantage of the Daline's ability to extract deeper bass from a driver through its quarter-wave action.

[BAM]

Well, if no one is willing to help me out on here, will someone please refer me to a person with whom I can carry on an email correspondence about this? I'd like to arrive at a viable Daline design because the Daline enclosure holds much promise for my particular application.

[GM]

For me, it's not a matter of won't help, but can't, due to the physics of the matter. How you figure these are suited for Daylines is beyond me. As I already stated somewhere in one of these threads, assuming the published Vas/Qts is remotely accurate, these are completely unsuitable for a Daline. The cab volume required to minimize the suckout above a way too low Fb for these drivers means that most of the 'line' is inside the cab. If you add a long vent it will be tuned extremely low, probably down in the 20-25Hz range. For Daylines, relatively high Vas/low Fs/low Q drivers is what you need.

FWIW, the lowest a driver can be loaded for good performance is ~Fs*0.707, so tuning a 105Hz Fs driver to 65Hz is not a good plan IMO.

For best overall performance, sticking them in a well stuffed ML-TL is probably your best bet with these, and add a sub for the bottom 2-3 octaves.

Using the PE specs I get:

L = 34.59"

6.96"w x 4.31"d

driver down 14.03"

vent = 3" dia. in 3/4" material

0.8-1.0lb/ft^3 stuffing

For two drivers:

L = 34.59"

9.86"w x 6.09"d

drivers down 15.31"

vent = 4.25" dia. in 3/4" material

0.8-1.0lb/ft^3 stuffing

These sim aneochoically flat to ~70Hz with a ~2.5dB gain above reference out to ~350Hz. Really, the sim looks much better than I would have thought. Also, instead of doing the driver layout per your dwg., I recommend using a bipolar layout for smoothest performance/baffle step compensation.

GM

[BAM]

Darn. I don't know scrap about ML-TLs. Could you refer me to some other projects that are ML-TL so I can see how they work?

[MJK]

My site has several examples of ML quarter wavelength designs, including the one that created the "ML" designation.

[kelticwizard]

BAM:

Now that I have Martin King's software functional, the next step is to figure it out. I have been looking at it, but it doesn't seem that intuitive. At least not for me.

I have wanted to use his software for many months, so I plan to go at it in the next few days. Once I get the "hang" of it, I will be glad to model both your Daline and Dave Jones'. Give me a little time here.

PS: Do you have Excel 2000? Because Excel 2000 will allow you to run a version of Unibox which takes the pipe resonance of a reflex into account. Since a Daline essentially appears to be a bass reflex with a port set up as a Transmission Line, it seems to me that you might be able to model one with Unibox-at least the version that takes pipe resonance into acount.

I don't have Excel 2000, so I am out of the picture, Unibox-wise.