Hey yall, I just finished TL B, except wood finish, sorry to say things did not come out as expected.
Started with idea that an 8" fr driver would supply enough bass extension, so looking at whats out there - Nirvana 8, Fostex 8, new Dayton ps220-8. Bought the Dayton and got no less than F3=150 hz. TL A is a 64" staight line, 48 in2, 1.7 cf, 22oz polyester. TL B is an 9" offset straight line with the same dimensions, which I thought would improve the situation... still F3=150hz.
Parts Express, Dayton ps220-8 specs using WT I = Fs 44, Qt .37, Qe .39,
Qm 5.3, Vas 2.2 cf, Sd 220cm2, re 6.3, le .65, 96db, BL 7.2 Tm.
Any Suggestions?
PS: I have tried and tried to convert bmps, to show a couple attachments,
couldn't figure it out- too big?
Started with idea that an 8" fr driver would supply enough bass extension, so looking at whats out there - Nirvana 8, Fostex 8, new Dayton ps220-8. Bought the Dayton and got no less than F3=150 hz. TL A is a 64" staight line, 48 in2, 1.7 cf, 22oz polyester. TL B is an 9" offset straight line with the same dimensions, which I thought would improve the situation... still F3=150hz.
Parts Express, Dayton ps220-8 specs using WT I = Fs 44, Qt .37, Qe .39,
Qm 5.3, Vas 2.2 cf, Sd 220cm2, re 6.3, le .65, 96db, BL 7.2 Tm.
Any Suggestions?
PS: I have tried and tried to convert bmps, to show a couple attachments,
couldn't figure it out- too big?
First suggestion-- convert those bmps to jpgs and you will have a lot better chance of loading.
Second -- Those three drivers require vastly different boxes. You do not mention the size of the open end. I'm guessing that it is the same area as the rest of the pipe and, yes, F3=150 sounds about right. Also 9" offset is way too little to have any real effect. But that effect has nothing to do with the tuning frequency, only reducing unwanted harmonics. you need to do some modeling if you want to get it right. the preferred software is HERE. Read the documentation there to get a handle on what the physics are with quarter-wave pipes.
Bob
Second -- Those three drivers require vastly different boxes. You do not mention the size of the open end. I'm guessing that it is the same area as the rest of the pipe and, yes, F3=150 sounds about right. Also 9" offset is way too little to have any real effect. But that effect has nothing to do with the tuning frequency, only reducing unwanted harmonics. you need to do some modeling if you want to get it right. the preferred software is HERE. Read the documentation there to get a handle on what the physics are with quarter-wave pipes.
Bob
FWIW, when I was having problems with this issue, Dave p10 posted that .gifs was the best choice for at least these forums and maybe on-line period [I can't remember now], but it has so far worked for me.
Not sure if it's typical, but the one 369 kb bmp example I've kept converted to a somewhat larger, 'whiter' displayed 832 kb jpeg/42 kb gif.
GM
Hi guys,
GIF is best for graphs because it compresses large blocks of repeating pixels. But it can't handle many colors simultaneously. It's limited to an "indexed palette." JPG is good for photos but sometimes it can make a graph with lots of solid white look a little gray or pinkish, in which case GIF is better.
GIF is best for graphs because it compresses large blocks of repeating pixels. But it can't handle many colors simultaneously. It's limited to an "indexed palette." JPG is good for photos but sometimes it can make a graph with lots of solid white look a little gray or pinkish, in which case GIF is better.
Play with this free program. For jpg's, set the max file size to 80k. Even at 800x600, the pictures will look fine on the internet and they will load in a flash.
Bob
Bob
Thanks Bob Brines for your info, the terminus for both are 6"x7". I read somewhere that
the chambered line has the lowest F3. I have read up on the Martin site, also the Augspurger tables. I leaned more toward the latter which calc'd F3 of ~70 but with a 3.3cf line. This would mean a box 2x my size (24" deep),
so goes the saying " T-Lines require a large box for bass extension ". Looks like with hind site I end up using a subwoofer for bass extension.
the chambered line has the lowest F3. I have read up on the Martin site, also the Augspurger tables. I leaned more toward the latter which calc'd F3 of ~70 but with a 3.3cf line. This would mean a box 2x my size (24" deep),
so goes the saying " T-Lines require a large box for bass extension ". Looks like with hind site I end up using a subwoofer for bass extension.
Greets!
Thanks! Yeah, found my notes, this is basically what Dave told me.
Thanks for the reminder, I've had this program for ages, but keep forgetting about it.
GM
Thanks! Yeah, found my notes, this is basically what Dave told me.
Thanks for the reminder, I've had this program for ages, but keep forgetting about it.
GM
Interesting, using Rick Shultz's Alpha TL designer based on Augspurger's tables, line length varies quite a bit for a given Fp based on whether it's fiberglass insulation or polyfil stuffed, so not sure what Fp you used, but in each case for a 44 Hz Fp the net Vb ranges from ~4.38 - 4.89 ft^3.
Using MJK's Classic TL alignment 44 Hz = ~6.98 ft^3, so yeah, 'there's no replacement for displacement' when there's a need/desire to go low at any useful SPL in a TL alignment.
For driver offset, MJK's L*0.349 works well.
GM
Who cares what it's called, providing it is clear what the goals of the cabinet are.
Alas, you don't seem to indicate a source for the article you reference above, and a brief search didn't reveal anything obvious (I don't have time to hunt down articles, assuming they're available), so I'm not sure how much use it will be at present. Got a link?
Alas, you don't seem to indicate a source for the article you reference above, and a brief search didn't reveal anything obvious (I don't have time to hunt down articles, assuming they're available), so I'm not sure how much use it will be at present. Got a link?
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Can't post a link since it appeared in Speaker Builder 2-1994 under Works in Progress. The author's speaker company website no longer on internet. There is a mention of his research in this link.
6moons.com - industry features: Terminus Longus
There has been much debate on many reviews of t-line speakers reviewed in many publications over the impedance peaks being that of a bass reflex design. There also has been much debate on t-lines on many audio forums on what the exact definition is.
6moons.com - industry features: Terminus Longus
There has been much debate on many reviews of t-line speakers reviewed in many publications over the impedance peaks being that of a bass reflex design. There also has been much debate on t-lines on many audio forums on what the exact definition is.
Ah. SB never made it to these shores. I did fire up the wayback machine though for his old site referenced on the 6moons page & he appears to be describing a damped 1/4 wave line, the density possibly decreasing toward the terminus.
Martin King has described the physics behind the twin impedance peaks referenced which are exhibited in undamped lines, or to a varying extent in those which are not ~critically damped for max-flat impedance, in considerable detail: http://www.quarter-wave.com/TLs/TL_Anatomy.pdf
Indeed there has, including multiple occasions here, so there doesn't seem to be much point in holding it [yet] again. FWIW the literal definition of the term is an untapered damped pipe with the sole object of providing the flattest impedance. It's rarely used so narrowly though.
Martin King has described the physics behind the twin impedance peaks referenced which are exhibited in undamped lines, or to a varying extent in those which are not ~critically damped for max-flat impedance, in considerable detail: http://www.quarter-wave.com/TLs/TL_Anatomy.pdf
Indeed there has, including multiple occasions here, so there doesn't seem to be much point in holding it [yet] again. FWIW the literal definition of the term is an untapered damped pipe with the sole object of providing the flattest impedance. It's rarely used so narrowly though.
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Over the years I have built many Fried t-line kits. The Fried designs and TDL designs [j. Wright] use the foam. and are free flowing. I have applied the Fried design parameters I deduced and they give flat results. Drivers with low Qts, and large Vas which have long xmas and large magnets work the best. High Qts. drivers work in t-lines but have the same limitations thay would have in other enclosures.
I dug through my closet for the 2/94 copy of Speaker Builder and read the article you reference. The author is right that the TL enclosure is a resonant design that when coupled to a driver will yield two impedance peaks, if the TL is not too highly stuffed. However, he describes the TL as having a Helmholz resonance which I believe is too simplistic. The TL's enclosure resonances are a series of standing waves with a fundamental frequency and many mathematically predictable harmonics. But the behavior is still the same and it creates two impedance peaks plus a few more smaller peaks at the higher harmonic frequencies. My TL Anatomy article goes into more details about the standing wave resonances, mating them with a driver, and the resulting system behavior.
Martin
Nice to hear from you Martin. I have discussed with you on the Yahoo t-line group the formulas I use being different then yours and Richard's for designing and finally testing the lines. I think Buggtussel Speakers has closed. The 2-94 article gave one of the best compialations of the theory about the different designs. I think it was far better then then Gary Galo's articles in 1982 about t-line theory, It is a good introductory in the basic theory. Speaker Builder and AES papers have given me the insight to many different design aspects of t-lines and series crossovers. The Fried and Wright designs are similiar. I found out from a fellow Fried speaker user that by upgrading drivers the stuffing density was greatly increased in one model the company offered an upgrade for. I suspect this is because the driver Vas are much different then the original drivers had.. His oem drivers versions had much longer motors then the stock versions. 8mm longer back plate on some models was quite common They have never given any of my amps a problem. I know of people using the same amp I have that run hot with speakers that offer a capacitive load to the amp.
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