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**Ujjwal** · 08-16-2020, 12:57 PM

I will try to upload a rough diagram of the design that i have thought out.

**Psycoacoustics** · 08-16-2020, 04:33 PM

Sounds like a job for Paul K. You may want to pm him.

Good luck! Mark

**tvrgeek** · 08-17-2020, 06:55 AM

Have you searched the WEB? A quick search came up with several pages. MTTL was all the rage 20 years ago, but has almost disappeared. Why? Well a properly designed ported enclosure works better, is smaller, and is easier to build. All the wonderful attributes about clarity were above the range where the cabinet had anything to do with it, so it being a TL vs ported was really more belief than science. Yes, if one is well executed, they do work and some fine speakers have been built using them.

This is a big step as a first build. Are you aware of the complexity of the total system design? The box is just one of many factors. Do you have a full suite of measuring and simulation tools?

So, you have a concept. Clearly a few things thought out.
You have picked drivers. ( hope not bought them yet, you are not ready)
Get the manufacturing data files, .frd and .zma. If you can only get graphs, not real files, there are programs that will trace a graph and produce a data file.
Pick a box modeling simulator. I actually do not know of one for a TL, but you can use one for ported so as to get a front baffle the size and shape you will have with the TL.
Pick a crossover simulator.
Model the system and see if the drivers you picked actually will work together. If so, then you buy them. ( or ask about experiences first)
You then mock up a prototype cabinet, mount the drivers and measure how they perform in the real world. Published files usually are close, but do consider them advertising, not engineering data.
Then you mock up the crossover, measure, tweak, listen. Eventually you decide you have the design.
Build your nice pair.

One tip I could suggest is to add a tweeter. I have played with the Mark 'full range" drivers and though they are wider band than most, I fount them very ragged and harsh on the top. Cone breakup. It is one of the few mid-ranges that can push the crossover up to 5K or so, but it gets nasty higher than that. 300 to 3K, really nice driver.

**Geoff Millar** · 08-17-2020, 07:59 AM

Originally posted by tvrgeek View Post

Have you searched the WEB? A quick search came up with several pages. MTTL was all the rage 20 years ago, but has almost disappeared. Why? Well a properly designed ported enclosure works better, is smaller, and is easier to build. All the wonderful attributes about clarity were above the range where the cabinet had anything to do with it, so it being a TL vs ported was really more belief than science. Yes, if one is well executed, they do work and some fine speakers have been built using them.

I'll put in a plug for TLs.

Paul K's designs have placed very well at speaker design competitions and he's helped many people, myself included, with MLTL and 'pure' TL projects, some of which are in the PE Project Gallery or Tech Talk. He kindly designed an MLTL for me based on the SB16pfc mid-woofer and I compared test builds of a vented design and Paul's design; the MLTL had more natural and extended bass than the vented cabinet.

Yes, the MLTL cabinet is larger, but that's not a big deal as both designs will need to be placed on stands for our use, anyway. The only extra work involved in the build was putting in an internal divider and getting the stuffing right.

I happily admit that the maths and physics of TL and MLTL design are totally over my head and there's no way I could design one, whereas I can now - after much help from PETT members - design a vented cabinet with WIN ISD.

Geoff

**Adam_M** · 08-17-2020, 08:22 AM

Originally posted by tvrgeek View Post

Have you searched the WEB? A quick search came up with several pages. MTTL was all the rage 20 years ago, but has almost disappeared. Why? Well a properly designed ported enclosure works better, is smaller, and is easier to build.All the wonderful attributes about clarity were above the range where the cabinet had anything to do with it, so it being a TL vs ported was really more belief than science. Yes, if one is well executed, they do work and some fine speakers have been built using them.

Are you sure about all of the bolded information? Salk, for example has a number of TL's, and I've read comments from he and other designers stating you can get more out of the bottom octave with TL's over ported designs. No argument from me on the fact that it's easier to build the ported cabinet though. You seem to present a lot of "facts" which are really your opinion (which is still extremely valuable information). Perhaps a slight re-wording so the opinion isn't presented in such an authoritative way could be better?

**tvrgeek** · 08-17-2020, 09:41 AM

I am sure on both statements. Built both side by side using the infamous B210*. Otherwise identical including the size and shape of the baffle. I rolled them off the top @ about 1K so no differences in crossovers or tweeters. The nice thing about the laws of physics is they are immune to bias. Back then, I was expecting the hype about them being so clean, so in a way I was biased in favor. TLs are more tolerant of TS parameters, but not completely. Well executed, they can almost match a well done ported. Slope is of course closer to first order rather then the QB4 second order. Correct cross section, taper, and how corners are dealt with can be tricky. I did not say they were bad. Just basically obsolete. Play with them, build them. Not a great idea for a first build though.

Totem sold some a while back, I believe, that were nice. Not sure I know of any volume current production TLs. I imagine there are a few niche products out there. They were far more common in the '80s. so yes, they have all but gone from the market place. So have things like the Dynaco tuned friction port, inverted dome tweeters, piezo tweeters, and a host of other things that seemed great at the time. A few years ago, silk was the best tweeter material, we have now moved past that. We have even finally given paper a run for it''s money in cones. We can buy poly caps big enough. ( I remember when a film 10uF cap was as big as a coke can)

I support your argument on size. What is the difference between a little box on a stand and a bigger box of the same footprint? Shipping cost mostly.

All too much of audio is "religion" rather than physics. I get the same kinds of arguments in the British car forum about oil brands. I too went down that rabbit hole many years ago. Go build two otherwise identical systems as I have. All the fancy descriptions on "clarity", "speed" "clean" etc are not attributes of the lowest octave unless due to a serious design mistake. I climbed back out of that hole and spent my time and money on drivers with lower distortion and improved crossover design.

*Actually built three TLs of different dimensions. Removable side so I could play with stuffing. Long hair wool was the magic back then, but I found differences to be very small. Density and change in density mattered more.

**Chris Roemer** · 08-17-2020, 09:46 AM

Don't fret, Adam.

tvr built speakers 40 y.a., but I don't believe he's been "current" in the hobby for over 20 (?).
Some of his (aged) opinions are still valid, others . . .

**Paul K.** · 08-17-2020, 09:57 AM

Not all drivers will work well in a TL and a small ported box will be the better choice, but one shouldn't poo-poo ML-TLs in general if one hasn't designed literally lots and lots of TLs for people around the world, including some for Salk Sound, Philharmonic Audio and other commercial entities, as well as a large number built for personal use. A proper ML-TL design using accurate TL-based software for the modeling, will be optimized in more ways than can be accomplished with typical ported box modeling software even where the line is not particularly long, like in a floor-stander where the internal cabinet height is the line length. My appreciation to Psycoacoustics, Geoff and Adam.
Paul

**Ujjwal** · 08-17-2020, 10:26 AM

Thank you all for your opinions and tips. Let me be more elaborative about my goal. My known informations are all gathered from reading different blogs and articles, so feel free to correct me as when needed.

1. A pair of floor standers for music. Music genres are
Indian film music, jazz, country and instrumentals.

2. Suitable for listening in medium to small room. High SPL is not a priority.

3. I aim to enjoy music and good sound and not really looking for perfect sound.

4. A medium to low budget project which will give good price to performance ratio.

These are my basic goals.

I have heard Markaudio Alpair 10p in a damped air coupler cabinets and i like them. But i am looking for a lil bit more slam and more amount of air movement.

â€‹â€‹â€‹â€‹Hence thought of adding woofer.

Mids are great in Markaudio drivers. Crossover can really be a villain ..so minimal crossover ( planning to use a passive line level crossover, 1st order , around 300 to 400 Hz) and a 2- way design in order to preserve mids and getting coherent sound.

Full range drivers (mid-tweeter) will be relieved from bass duties and will produce cleaner mids with less distortion.[ woofer assisted wideband ..or F.A.S.T.]

I like clean extended bass response, hence looking for MLTL housing for the woofer( though the Peerless woofer has a Qts of 0.31 and not very ideal for MLTL application).

Markaudio Alpair 7 ms are comparatively new driver and they are spider- less. I did not listen them but have read that they are not harsh and beaming problem is much less.

Lastly in India, speaker drivers are not widely available. So i am afraid i i will not have wide array of choices to pick the most suitable driver.

I hope project goals are more clear to everyone now.Please feel free to express your thoughts.

**a4eaudio** · 08-17-2020, 12:39 PM

Originally posted by tvrgeek View Post

I am sure on both statements...

Totem sold some a while back, I believe, that were nice. Not sure I know of any volume current production TLs. I imagine there are a few niche products out there. They were far more common in the '80s. so yes, they have all but gone from the market place.

https://www.parts-express.com/dayton...-pair--300-658

**Paul K.** · 08-17-2020, 01:36 PM

Just to see what might result, I modeled an ML-TL for this Peerless woofer. This isn't necessarily what Ujjwal might want, cabinet-wise, but it shows that this driver does model quite well. The attached sheet shows 3 graphs. First is the system bass response that has an f3 of 35-36 Hz and really smooth overall response. You'll note the SPL output is just over 104 dB. The actual output will be lower once BSC is incorporated but will be 100 dB or so, and at one meter, that's plenty loud. I chose the stated input power because that's what will push the woofer to Xmax, and that is shown in the second graph. Xmax is 5.5 mm Peak, which is 3.9 mm RMS, the units on the Y-axis of the graph. The woofer reaches Xmax at 50 Hz. The last graph shows the port's air velocity as a percentage of the speed of sound. The peak velocity is ~3.3% which equals just over 11 m/s and commendably low, occurring at ~36 Hz. Ujjwal, if you want to pursue this or another design more to your suiting, send me a private email containing your email address and we can proceed. Edit: The width of the cabinet I modeled was 9" not 9.5" as stated in the attachment.
Paul
ML-TL for 830869.doc

Attached Files

ML-TL for 830869.doc (798.5 KB, 237 views)

**tvrgeek** · 08-17-2020, 05:04 PM

"Crossover can really be a villain ..so minimal crossover ( planning to use a passive line level crossover, 1st order , around 300 to 400 Hz) and a 2- way design in order to preserve mids and getting coherent sound."

Yes, if not done well they are the villain. If done right they are where the magic comes together. The crossover is 90% of a speaker system design. Boxes are the easy part. I fell for the minimal, coherent-purity stuff. I learned better as mother nature has different ideas. The center I just finished ( so much for not being active) is an LR-4 acoustic built with 3rd and fourth electrical crossovers. Zobel on the woofer, notch on the tweeter. 20mm AC offset compensated for. Measured in place using MLS, 1M within 1.5 dB from 400 to above 15K. Part of the crossover design is getting the time and phase correct through the crossover. I cheated on this as an AV center and had the ARC DSP program in my Anthem do the BSC for me. It would have needed a 12mH coil!

Phase coherent. At a point source, possible. Move a foot and they will not be. Sounds great in a magizene review but the real world has other ideas.

One of the problems with low order crossovers is you can't play with the phase and Q like you can with high order. You don't have the parts to play with! So they are actually harder to get coherent through the crossover. A fad a while back was driver offset "time alignment" Some made it work many did not. Vanderstein 2Ce got it right.

Beaming is a matter of physics. It is directly correlated to the diameter of the driver. The only way to change that is with a lens.

I can see from Mark Audio frequency plot the breakup I experienced with the older ones. Again, no magic. Just because they do a better job than others for a wider band with driver does not mean they can bend the laws of physics. Still a really good mid and should match to the woofer, but leave yourself room on the baffle to add a tweeter as you are going to want one.

Wisdom from an old guy who went through these things years ago. I don't have anything to sell and only need to please the better half and myself. Nothing I have learned has not been learned by many others. I too had to prove it to myself. The only thing that has changed is the drivers are getting better and better. Physics has not changed in 13.8 billion years.

A4,
PE is a parts and kit supplier. They are not production units available in retail stores. I searched earlier and came up with two, very limited, very expensive, never seen in a store.

Paul,
Am I reading your model right that it is a third order? What program do you have that models a TL? Last time I fooled with them we only had rough guesses on length and rumors on taper. Models did not account for reflections from folds or diffraction around dividers. Bendy plywood is handy BTW. Some insane systems have been cut from layers of MDF and laminated to get good radius internally with no reflections.

Same religious arguments on if the exit should be on the front or on the back. Mine were on the back but for no reason other than where the line finished.

Boh thunder boomer. urning off th computer.

**Paul K.** · 08-17-2020, 06:31 PM

While all TLs are inherently 4th order, the initial roll-off that results can be less, even 2nd order, depending on the driver and TL design, but at some lower frequency will become 4th order. I use Martin King's software for all of my modeling which is NLA, but I have it on 2 computers and on backup disks just in case. There's no guessing required. His software also includes stuff for sealed boxes and any kind of ported box you can imagine. I've modeled and built tapered TLs with taper ratios up to 25:1 that have worked very well. Putting curved or angled deflectors in the bends of folded lines is completely useless primarily because the wavelengths left over after the sound passes through the fiber fill are too long to even "see" the bends.The fiber fill absorbs all of the higher frequency stuff including anything from reflections. I've built TLs with exits/ports on back panels and baffles; either location is fine as long as an exit on the back isn't jammed against a wall. Contrary to some beliefs, long-fiber wool is not better than other materials; all of them work the same way but require different densities to give identical results.
Paul

Originally posted by tvrgeek View Post

[I]"
Paul,
Am I reading your model right that it is a third order? What program do you have that models a TL? Last time I fooled with them we only had rough guesses on length and rumors on taper. Models did not account for reflections from folds or diffraction around dividers. Bendy plywood is handy BTW. Some insane systems have been cut from layers of MDF and laminated to get good radius internally with no reflections.

Same religious arguments on if the exit should be on the front or on the back. Mine were on the back but for no reason other than where the line finished.

.

**Ujjwal** · 08-17-2020, 10:02 PM

Originally posted by Paul K. View Post

Just to see what might result, I modeled an ML-TL for this Peerless woofer. This isn't necessarily what Ujjwal might want, cabinet-wise, but it shows that this driver does model quite well. The attached sheet shows 3 graphs. First is the system bass response that has an f3 of 35-36 Hz and really smooth overall response. You'll note the SPL output is just over 104 dB. The actual output will be lower once BSC is incorporated but will be 100 dB or so, and at one meter, that's plenty loud. I chose the stated input power because that's what will push the woofer to Xmax, and that is shown in the second graph. Xmax is 5.5 mm Peak, which is 3.9 mm RMS, the units on the Y-axis of the graph. The woofer reaches Xmax at 50 Hz. The last graph shows the port's air velocity as a percentage of the speed of sound. The peak velocity is ~3.3% which equals just over 11 m/s and commendably low, occurring at ~36 Hz. Ujjwal, if you want to pursue this or another design more to your suiting, send me a private email containing your email address and we can proceed. Edit: The width of the cabinet I modeled was 9" not 9.5" as stated in the attachment.
Paul
ML-TL for 830869.doc

Thank you Paul. This looks very nice indeed. I will contact you.

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Help needed to model MLTL cabinet for Peerless 830869 8 inch Nomex cone woofer

Help needed to model MLTL cabinet for Peerless 830869 8 inch Nomex cone woofer

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