Oh, i am sorry, i mis-read about the passive part. My bad.
Yes, the FE166 arrived last week-end.
I am coming close now to consider a ML TQWT for my Fostex. The link from mh-audio.nl has a basic TQWT calculator which i can work on to get the rough-cut dimensions mh-audio Tapered Quarter Wave Tube
I am going with the tuning freq = resonance freq of the driver which gives me modest dimensions catering to my room size. Please suggest if this is a wise decision considering my room size and choice of the box gemotery / loading.
BR,
Or grab a copy or Leonard Audio Transmission Line software......
Leonard Audio | Audio Engineering Resources
IMO well worth considering building a mass loaded tube rather than a more traditional one. The harmonics and resonances may be more tightly controlled.
Leonard Audio | Audio Engineering Resources
IMO well worth considering building a mass loaded tube rather than a more traditional one. The harmonics and resonances may be more tightly controlled.
That calculator is not much better than a joke. It is likely that best performance can be had with an ML-TL or ML-TQWT (considerablt larger). Use Leonard sw to simulate a decent enclosure. If Bob Brines work on an ML-TL is any indication, you will still be bass-shy.
dave
Thanks for the suggestion. The Cyburg's Needle still will be a largish enclosure for my room. Tabaq could be one option to consider. Tallish speakers is again one problem as it can give a cluttered look IMO.
Thanks to both Jerms and Planet10 for the Leonard SW link and suggesting the box geometry and calculation link. Will explore them later in the day and come out with questions.
I played with the Leonard Audio software for a couple of days / weeks and tried various geometry (tapered, straight, expanding) and finally am coming close to select the straight line TL. Mass loading the line moves the tuning frequency lower which needs me to reduce the line length even further beyond practical values.
I used the MJK alignment tables worksheet to arrive at the cross-section area and line length for a tuning freq of 55Hz (which is close to the resonance of the FE166en). The driver off-set is also as per suggested offset in the alignment table. This is giving me a slim-profile box as suggested by Jerms and i am okay with the suggested dimensions.
I am not sure if the effect of adding / removing stuffing is simulated correctly in the software but again this can be measured / listened and adjusted after subjective listening.
Will post the simulated images over the weekend.
Thanks for looking
I used the MJK alignment tables worksheet to arrive at the cross-section area and line length for a tuning freq of 55Hz (which is close to the resonance of the FE166en). The driver off-set is also as per suggested offset in the alignment table. This is giving me a slim-profile box as suggested by Jerms and i am okay with the suggested dimensions.
I am not sure if the effect of adding / removing stuffing is simulated correctly in the software but again this can be measured / listened and adjusted after subjective listening.
Will post the simulated images over the weekend.
Thanks for looking
I am now trying an expanding taper design with a Taper Ratio of 2. Below are the other parameters of the design. These have been derived from MJK's alignment tables
S0 = 77.116 sq.in
SL = 154.232 sq.in
SL/S0 =2
Leffective = 64 in
Lactual = 61 in
Tuning freq = 60Hz
Offset = 22.567 in (tweaked) calculated = 22.274 in
Preferred stuffing = 0.78 lb/ft3
This is what i get from the LA for the stuffed and unstuffed line:
It will be great if the experts pitch in and help me validate my design. I may have some free time next weekend and will start building the box with Carpenters help.
Thanks in advance.
S0 = 77.116 sq.in
SL = 154.232 sq.in
SL/S0 =2
Leffective = 64 in
Lactual = 61 in
Tuning freq = 60Hz
Offset = 22.567 in (tweaked) calculated = 22.274 in
Preferred stuffing = 0.78 lb/ft3
This is what i get from the LA for the stuffed and unstuffed line:
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.
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.
It will be great if the experts pitch in and help me validate my design. I may have some free time next weekend and will start building the box with Carpenters help.
Thanks in advance.
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This is what i will be finally deciding to built the box as. It will be a ML-Straight Line TL tuned at around 57Hz. Below are some images of the simulation on LA software,
This is how the box is going to look. The ML-terminus is at the bottom front.
Awaiting suggestions on the simulations and expert advise before the first wood is cut for the box next month.
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.
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.
This is how the box is going to look. The ML-terminus is at the bottom front.
An externally hosted image should be here but it was not working when we last tested it.
Awaiting suggestions on the simulations and expert advise before the first wood is cut for the box next month.
Last edited:
Hi
I recall many years ago building Alpha TL for the Fostex 167 not paying attention to amplifier output impedance and just following the formulas from the AudioXpress article. It turn out great, actually won a prize in a local DIY contest up against other different solutions using the same driver. Gave them away to a relative that is still using them today.
Very easy cabinet for a first build...didn't over engineer the stuffing either... just wrapped the inside with short hair carpet in the area around the back of the driver going a bit above and below the driver to reduce reflections thru the cone. Kept the rest of the inner walls on wood. Little corner feet to lift the pipe off the ground to allow bass to flow under and out. I can't recall how high was that clearance at the bottom but there was plenty of bass.
Seems to me the nature of the Alpha TL is if you plug in the values it accommodates just about any driver, but granted a driver with a very low Qts is best in horn of some kind. And your driver has a lower Qts than the 167. But still worth a try for sure before building something more difficult.
I have un-used pair of L.CAO non-Alnico with a Qts of .65 purchased years ago still the original box that I will most likely put in A-TL one day.
cheers
Paba
I recall many years ago building Alpha TL for the Fostex 167 not paying attention to amplifier output impedance and just following the formulas from the AudioXpress article. It turn out great, actually won a prize in a local DIY contest up against other different solutions using the same driver. Gave them away to a relative that is still using them today.
Very easy cabinet for a first build...didn't over engineer the stuffing either... just wrapped the inside with short hair carpet in the area around the back of the driver going a bit above and below the driver to reduce reflections thru the cone. Kept the rest of the inner walls on wood. Little corner feet to lift the pipe off the ground to allow bass to flow under and out. I can't recall how high was that clearance at the bottom but there was plenty of bass.
Seems to me the nature of the Alpha TL is if you plug in the values it accommodates just about any driver, but granted a driver with a very low Qts is best in horn of some kind. And your driver has a lower Qts than the 167. But still worth a try for sure before building something more difficult.
I have un-used pair of L.CAO non-Alnico with a Qts of .65 purchased years ago still the original box that I will most likely put in A-TL one day.
cheers
Paba
Interesting, if I recall the original article formulas didn't make it really clear the position of the driver if I recall. the length dimensions of the pipe yes but not the position of the driver. I had to contact the author...if I recall.
/Paba
Thanks Dave and GM for review of the simulations and your suggestions. When i offset the driver as per MJKs alignment table the odd harmonic wrinkles become very bad, the TL acoustic Z becomes bad. Only the 3rd harmonic spike goes away from the Electrical Z. Also the overall FR at low-end becomes weak with the offset. I have 2 questions here,
- in a ML-SL do we have to tune the speaker system @ resonace, below resonance or above resonance
- Does the MJK alignment table hold true for a ML-SL enclosure too.
Thanks in advance for your valued suggestions.
Kind Regards,
Hari.
Thanks Paba for reviewing the simulations and giving your experience with the Alpha TL geometry. I too have built a Alpha-TL but with a 2way speaker system. The line length being low allows a tight bass but the low freq extension is not very good. Also the enclosure is over-damped and removing the stuffing makes the bass a bit loose IME.
I am planning to add a ML small port to this speaker to check if i can get a little more bottom-end with this speaker. This will also help me to validate my design with the LA.
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