Boy are you all wet in generalizing that just because a tapered TL has a ratio of 10:1 there will be zero output from the terminus. I believe you are equally wrong in saying that simulations always exaggerate ripple in the terminus' output, but I can't readily prove that. I'm going to attach a word document showing three graphs representing the performance of an 18:1 tapered TL I built several years ago. The red line in the first graph is the system response, the combined responses of woofer and terminus. The red line in the second graph is that of the woofer, and the dashed blue line is that of the terminus. Clearly, the output of the terminus has far more than zero output, thereby providing plenty of bass reinforcement, which is the goal, and this is with a 18:1 taper! There are enough TL myths and incorrect Rules of Thumbs that have been postulated already over the years that continue to confound newbies; please refrain from starting new ones.
Check out some of my posts on diyaudio... I've built and measured a ton of horns, tapped horns, and a few transmission lines.
I would discourage you from building a transmission line with a ration of 10:1. With a ratio like that, there is virtually zero output emanating from the end of the line.
What you end up with is a response which is virtually equivalent to a sealed box, and a design that's a lot of hassle to build. What works better is to use a big mouth, ideally twice as big as the woofer itself. Don't fret if there's ripple in the simulated response; the simulations always exaggerate ripple.
Check out some of the designs from Bob Brines or Terry Cain - these guys know how to deliver real dynamics from a line. Designs like that are particulary exciting with low powered amps.
Could I interest you in a tapped horn?
Paul,
Thanks for that. It needed saying.
A heavily tapered line is actually capable, in theory, of producing more bass augmentation. The heavy taper improves the low pass function of the terminus so you can use less damping to get rid of the ripple, and allow more of the fundemental to get out.
dave
Thanks for that. It needed saying.
A heavily tapered line is actually capable, in theory, of producing more bass augmentation. The heavy taper improves the low pass function of the terminus so you can use less damping to get rid of the ripple, and allow more of the fundemental to get out.
dave
You are entirely welcome, Dave, and it sure did need saying. Sometimes people make incorrect generalizations based on good intentions and some resemblance to facts, but those were so off base and wrong I can't imagine why they were stated, and just couldn't "look the other way".
Paul
Paul
Patrick,
Paul and Bob Brines both make liberal use of Martin J. King's worksheets. They also have many examples of transmission line speakers designed and built so I trust the theoretical basis for their designs. I have also used Martin's work and I respect the ability of his simulations to yield the predicted results.
Jim
Paul and Bob Brines both make liberal use of Martin J. King's worksheets. They also have many examples of transmission line speakers designed and built so I trust the theoretical basis for their designs. I have also used Martin's work and I respect the ability of his simulations to yield the predicted results.
Jim
I was thinking the same thing. Only thing I don't understand why physically aligning drivers is so important. If you're ear level is vertically equidistant from a woofer and a tweeter and the woofer's acoustic center is 30 mm deeper the sound from the woofer gets to your ear 1 ms after the sound from the tweeter. If move you head down 8 cm, if you have a 4" flange tweeter and 6" flange woofer and about a meter away, the time alignment is perfect. Seems like a lot of fussiness with little to gain. Or you could lose because you're listening to the drivers slightly more off-axis.
I didn't slant the baffle because I think it looks strange and I didn't want to make angle cuts
The slope order 'steers' the HF output over a vertical arc. For example:
http://www.rane.com/pdf/ranenotes/Linkwitz Riley Crossovers Primer.pdf
GM
http://www.rane.com/pdf/ranenotes/Linkwitz Riley Crossovers Primer.pdf
GM
i agree with most of what scootmoose has said...there are pros and cons to any design philosophy...some BR's are good, some TLS are good...also whatevr TL QWTL MLTL BR there are resonances to deal wiuth somehow.
combing caused by using a pipe is more of a problem in my opinion as it affects a broader range of frequencies and is hence more audible that a narrow high q peak at over a smaller range but of equal magnitude, which is why i doubt theie audibel superiority. Impeadance and amp loading is their advantage. However, with modern amps and also in multiway designs, how much does this gain? With a valve amp the advantage would be greater i suspect and im not a valve advocate(sorry guys) excepty that is for my guitar amplifier, where the even order harms are better sounding!!
a\lso on the point of group delay...if well designed a BR CAN be very well damped and i believe it is fairly well known and agreed that delays of less than 12 ms arent audible (chorus pedals use delays 16ms + give their sound effect) so i doubt that anything other than a very poor BR would have audible group delay.
again all design are a comprimise, if i could have a full range horn system 20-20000hz i would but i dont have a spare house to put it in!!!
It is indeed too bad that you are so set in your ideas about what a good 6.5" driver can do in the properly sized and built enclosure. The sentence underlined above is absurd! I must own those "magical unicorn / enhanced Vodoo chicken footed / impossible extension speakers"! My lucky day! Do they replace a good subwoofer? Of course not. But they do go below 30Hz.
All the people at "Burning Amp 1" will disagree with you. They heard it for themselves. In a TL enclosure, underpowered in an acoustically poor environment no less. Wish you were there, this thread would not exist. No amount of information or data will make a difference, I have posted the SPLs from when the drivers weren't broken in, I would expect them to be even better now.
My hats off to "Mr. Moose and Dave" for their knowledge and support. I am a big fan of theirs. I know many others are too. Jackinnj is another. He has a set of impossible excursion speakers too!
Ron
A six and a half inch driver might look spectacular doing such cone excursions, and this does delite a certain type of audience, but how much distortion was it producing etc. you dont say, but I already know, far more than can be accepted as oppropriate for good queality sound reproduction, and I don,t need to be a genius to figure that out
rcw.
rcw.
I apologize if that was improper. I was simply stating my personal experiences of what I, and others have observed. Not theory. I also stated they do NOT replace and cannot replace a subwoofer. No one likes being impugned or belittled. It only becomes personal.
Some people enjoy monster bass in their cars from 3 15" subs. I suspect therein lies the difference, full bass or butt shakin' bass. I'm happy with my full bass, no subs needed for critical stereo listening. Movies are a different story.
Ron
Some people enjoy monster bass in their cars from 3 15" subs. I suspect therein lies the difference, full bass or butt shakin' bass. I'm happy with my full bass, no subs needed for critical stereo listening. Movies are a different story.
Ron
Interesting thread that seems to have degenerated a little. I particularly enjoyed reading MJK's posts. A lot of what has been said by others has been strong opinion backed up by little or no evidence. All this stuff has been interesting to me because I have recently completed a project where I built a pair of BR and pair of MLTL speakers with the same drivers. I bought 2 pairs so could hear them side by side. The design brief came from the other half, typical woman - make em small, and since invisible is not possible, make them look like fine antique furniture. So I thought small BR would be cute and went ahead and built them from solid wood. They certainly are cute, and she loves them. Comment from the other half - "See, you can make small speakers that sound really good" - followed by a groan from me. Then I thought it would be interesing to try a MLTL as well, so bought another pair of drivers and made the MLTL, also from solid wood. Started to regret that half way through. Cost of materials was around 3 times the BR because of the increased cabinet size, and was around 3 times as much work. They don't look so cute, and she does not like them as much as the BR. Bummer.
Now, what about sound. The MLTL unquestionably sounds better, and the other half does agree with that. Deeper and cleaner bass, and cleaner midrange. The BR sounds brilliant on some CDs, not so brilliant on others. The MLTL sounds good on just about anything. What does that prove. Not a lot. This (small FR) driver sounds better in the MLTL, and I like it, the other half likes the BR. Whatever floats your boat. It does show why there are hardly any commercial TLs. Cost. It has nothing to do with any inherant advantage of BR. As already frequently stated, both have advantages and disadvantages, and the advantages of one or the other will appeal or not appeal to individual tastes and circumstances. Personally I don't accept the strongly opinionated statements of individuals pushing one or the other, but I have built them all and have had very good success with MLTL designs. I am prepared to wear the disadvantage of bigger cabinet and cost, and I do like the sound I get from the MLTL's. This is DIY after all, do whatever you like, and there is no point in getting all hot under the collar about one design choice over another.
Now, what about sound. The MLTL unquestionably sounds better, and the other half does agree with that. Deeper and cleaner bass, and cleaner midrange. The BR sounds brilliant on some CDs, not so brilliant on others. The MLTL sounds good on just about anything. What does that prove. Not a lot. This (small FR) driver sounds better in the MLTL, and I like it, the other half likes the BR. Whatever floats your boat. It does show why there are hardly any commercial TLs. Cost. It has nothing to do with any inherant advantage of BR. As already frequently stated, both have advantages and disadvantages, and the advantages of one or the other will appeal or not appeal to individual tastes and circumstances. Personally I don't accept the strongly opinionated statements of individuals pushing one or the other, but I have built them all and have had very good success with MLTL designs. I am prepared to wear the disadvantage of bigger cabinet and cost, and I do like the sound I get from the MLTL's. This is DIY after all, do whatever you like, and there is no point in getting all hot under the collar about one design choice over another.
Driver choice was the Alpair 6. BR was tuned to 62Hz. Internal dimensions 26 x 13 x 17 cm, port diam 3cm, length 7.4cm, lightly stuffed. Constructed from solid Tassie Oak and Myrtle. Real cute, and she loves them.
MLTL internal was 11.2 x 11.6 x 85cm. Port 3cm diam, length 5.4 cm, located on the back at the bottom. Tuned to 48Hz. Driver is 19.9 cm from the top. Stuffed to 42 cm from the top at 14g/l. These I made from Tassie Myrtle, with a Jarrah base, and inlaid strip of Jarrah up the front. Elegant small tower, she accepts them.
Here they are
They won't win any prizes for bass, but what bass is there is clean and surprisingly deep for such a small driver. The BR sounds best corner loaded. I do like the MLTL. A sub would be nice, but at the moment they are in my main system with no sub. The Alpair 6 has an exceptional midrange, it does things my electrostatic does in the mids. At first I was a bit disappointed with the Alpair treble, but they do need an extended run in period to sound at their best. The other half hates my electrostatic - "It's TOO BIG", but but dear, they sound divine. Unforunately sounding divine just doesn't cut it. They are in the holiday house. Good reason for holidays!
MLTL internal was 11.2 x 11.6 x 85cm. Port 3cm diam, length 5.4 cm, located on the back at the bottom. Tuned to 48Hz. Driver is 19.9 cm from the top. Stuffed to 42 cm from the top at 14g/l. These I made from Tassie Myrtle, with a Jarrah base, and inlaid strip of Jarrah up the front. Elegant small tower, she accepts them.
Here they are
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They won't win any prizes for bass, but what bass is there is clean and surprisingly deep for such a small driver. The BR sounds best corner loaded. I do like the MLTL. A sub would be nice, but at the moment they are in my main system with no sub. The Alpair 6 has an exceptional midrange, it does things my electrostatic does in the mids. At first I was a bit disappointed with the Alpair treble, but they do need an extended run in period to sound at their best. The other half hates my electrostatic - "It's TOO BIG", but but dear, they sound divine. Unforunately sounding divine just doesn't cut it. They are in the holiday house. Good reason for holidays!
Hello again friends,
I decided to round over my ports with a 1/2" round-over bit because that is all they had at the hardware store. Then I went to the hardware store again rescently and found a 3/4" hardware bit.
Is the port likely to have less noise if I use a 3/4" round-over bit? I would have to try to smash the ports out with a hammer The pictures are where the front baffle goes. The port exits out the back and still needs to be routed out. I wish I could make my picture thumbnails smaller.
I decided to round over my ports with a 1/2" round-over bit because that is all they had at the hardware store. Then I went to the hardware store again rescently and found a 3/4" hardware bit.
Is the port likely to have less noise if I use a 3/4" round-over bit? I would have to try to smash the ports out with a hammer
The pictures are where the front baffle goes. The port exits out the back and still needs to be routed out. I wish I could make my picture thumbnails smaller.An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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Jimmy,
I don't quite understand what you are asking / saying.
"The port exits out the back and still needs to be routed out."
It looks like your building a slotted port, Is that right?
"Is the port likely to have less noise if I use a 3/4" round-over bit?"
Short answer is Yes, longer answer is it may not make much real world difference. Depends on the projected velocity and area of the port.
"I would have to try to smash the ports out with a hammer"
Are you asking about rounding over the INSIDE of the port? or the outside?
Seems like you are asking about the inside, if that's the case I'd say leave it alone and keep building.
Some more information would be helpful, what size are your drives and what is their projected max excursions?
Ron
I don't quite understand what you are asking / saying.
"The port exits out the back and still needs to be routed out."
It looks like your building a slotted port, Is that right?
"Is the port likely to have less noise if I use a 3/4" round-over bit?"
Short answer is Yes, longer answer is it may not make much real world difference. Depends on the projected velocity and area of the port.
"I would have to try to smash the ports out with a hammer"
Are you asking about rounding over the INSIDE of the port? or the outside?
Seems like you are asking about the inside, if that's the case I'd say leave it alone and keep building.
Some more information would be helpful, what size are your drives and what is their projected max excursions?
Ron
Yes.
Yeah, I'm asking about the inside. The outside I will route with the 3/4" bit where I can.
I'm using ScanSpeak 21W/8555-01 per 1.70 cu. ft. enclosure with a 1 x 8.5 x 19.5" port with .3 lbs/cu.ft. polyfill. I don't plan to play them very loud, but it would be just dandy if they could without port noise.
Why is your smiley bleeding?
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