Hmm, if my calc was 15", then the info I had was different than these dims which calc a ~14.82" (14-13/16") i.d. offset, though of course there shouldn't be any audible/subjective difference with just a 1.2% error.
While I prefer a golden or acoustic ratio WxD, with a double ~616 Hz 1st mode due to being a square section there might not be enough acoustic energy coming off the backside of the driver to audibly excite it, though best to at least put some felt on one side and rear directly beside/behind the driver on one side/back panel just in case and of course some at the top to damp the much lower frequency pipe harmonics from reflecting out through the driver via modulating it.
GM
While I prefer a golden or acoustic ratio WxD, with a double ~616 Hz 1st mode due to being a square section there might not be enough acoustic energy coming off the backside of the driver to audibly excite it, though best to at least put some felt on one side and rear directly beside/behind the driver on one side/back panel just in case and of course some at the top to damp the much lower frequency pipe harmonics from reflecting out through the driver via modulating it.
GM
Well I didn't cut anything yet. But fractions of inches and one percent variances I can live with.
The box can be conceivably 11 1/4 in wide if I do no further trimming of
the width.
If the day comes when I have the means to get some fresh panels, I could go the whole route with a 48" length as discussed above.
For now I am still learning to use the router.
The 167e is fairly happy where it is in the small test box. I think the
3 ft. should be tuned high rather than low.
For the port dimension, I noted 3" and length of 1 1/2 in-- little more than the bottom plate. Still I want the bottom exit and stand mount.
If the speaker front wave is a balloon shape what shape is the
sound wave at the terminus? I have been notably confused by that
for a long time.
The box can be conceivably 11 1/4 in wide if I do no further trimming of
the width.
If the day comes when I have the means to get some fresh panels, I could go the whole route with a 48" length as discussed above.
For now I am still learning to use the router.
The 167e is fairly happy where it is in the small test box. I think the
3 ft. should be tuned high rather than low.
For the port dimension, I noted 3" and length of 1 1/2 in-- little more than the bottom plate. Still I want the bottom exit and stand mount.
If the speaker front wave is a balloon shape what shape is the
sound wave at the terminus? I have been notably confused by that
for a long time.
The 3" dia. x 1.5" was for the 127E. For the 167E, 4" dia. x whatever length sounds best to you. FWIW, with the smaller 11" square layout it needs to be 1.5" long to tune it to the published Fs, so as good a place as any to start.
The port functions ~as an acoustically tiny point source, so due to its low BW it radiates primarily as pressure waves and eventually many dB lower will begin radiating hemispherically once its harmonics have decayed to a high enough frequency to launch off the baffle.
GM
The port functions ~as an acoustically tiny point source, so due to its low BW it radiates primarily as pressure waves and eventually many dB lower will begin radiating hemispherically once its harmonics have decayed to a high enough frequency to launch off the baffle.
GM
Ok. What you said.
Thanks for this last little piece of the puzzle for the port. I still have some 4 inch around.
The confusing part for me is the radiation at the port.
If radiation at the terminus is 90d of the opening then the bottom is the right place for the port and the port in 'free air' rather then flush with a side or slotted in the bottom would give a better pattern of sound dispersion. That's just my take on it.
Launching off the baffle still mystifies. How would launching off the baffle work with one of those Fonkens cut at 45d?
Thanks for this last little piece of the puzzle for the port. I still have some 4 inch around.
The confusing part for me is the radiation at the port.
If radiation at the terminus is 90d of the opening then the bottom is the right place for the port and the port in 'free air' rather then flush with a side or slotted in the bottom would give a better pattern of sound dispersion. That's just my take on it.
Launching off the baffle still mystifies. How would launching off the baffle work with one of those Fonkens cut at 45d?
Consider the size of a 50 Hz sound 'bubble', its diameter is ~13560"/50/pi = ~86.3", completely dwarfing/encasing the speaker's bulk, so its radiation is effectively omni (360 deg), reflecting off any boundaries within its 'bubble' until it finally decays to half space (AKA 2 pi or 180 deg) on the baffle way up in frequency, ergo any angles are transparent to it until way up in frequency. By the time it decays to 90 deg its output is so low that we can say that the vent has become effectively damped shut, ergo any angled vent terminus can only affect its effective vent length and the baffle's eigenmodes (standing waves) AFAIK.
GM
GM
I should be doing the trim cuts on these pieces soon. I don't like to overburden my cutter with more than a once a week vist during "build season."
The inexpensive solution to damping is fiberglass sold in small roll amounts for filling things like outlet boxes in walls. But I'm not really ape about handling the stuff even with gloves.
This town must be totally gentrified. There is a new 'green friendly'
carpet place that is open by appointment only. They prob'ly do not want to take appointments for gimmes and handouts of remainders-- even if they had the felt underly stuff.
The inexpensive solution to damping is fiberglass sold in small roll amounts for filling things like outlet boxes in walls. But I'm not really ape about handling the stuff even with gloves.
This town must be totally gentrified. There is a new 'green friendly'
carpet place that is open by appointment only. They prob'ly do not want to take appointments for gimmes and handouts of remainders-- even if they had the felt underly stuff.
don't let this happen to you
Don't let this happen to you.
No I still have all my fingers (and toes.)
I finally got my trimmed pieces from the cutter, made the adjustment that GM gave o0f 14 and 3/16.
But in doing the cutout something went awry. The through cut (as opposed to the separate face cut done as a rabbet) was too small. After all the test cuts, something went wrong and I don't even know where for sure.
So I'm finishing by hand with a half round file and a piece of pvc with and sandpaper. It will take a while but I have no choice.
There is hand flaring to do on the backside cutout as well which I practiced on one of many practice circles and make-do trammel.
But right now I have to get the 167e to go into the opening yet.
Don't let this happen to you.
No I still have all my fingers (and toes.)
I finally got my trimmed pieces from the cutter, made the adjustment that GM gave o0f 14 and 3/16.
But in doing the cutout something went awry. The through cut (as opposed to the separate face cut done as a rabbet) was too small. After all the test cuts, something went wrong and I don't even know where for sure.
So I'm finishing by hand with a half round file and a piece of pvc with and sandpaper. It will take a while but I have no choice.
There is hand flaring to do on the backside cutout as well which I practiced on one of many practice circles and make-do trammel.
But right now I have to get the 167e to go into the opening yet.
What I thought would be a big job got done yet this afternoon.
Lots of elbow grease.
Having a big chamfer bit would be nmore fun than a file but
a file gives more control.
Now all I need to know is what is a good kind of file to do this--
one that hogs out a lot of material. I bought a $4. one from the Menards handyman store. It's too small but will work for this job.
Lots of elbow grease.
Having a big chamfer bit would be nmore fun than a file but
a file gives more control.
Now all I need to know is what is a good kind of file to do this--
one that hogs out a lot of material. I bought a $4. one from the Menards handyman store. It's too small but will work for this job.
The wood rasp sounds like the right one. I'm not enough of a Giapetto to throw down $16 for the file and $11 for the handle, but I
will keep my eye out for deals on rasps.
Glue up should commence fairly soon on this one. I have 2 sides of the flare left to complete.
I gave up on looking for felt. I have some 3/4 medium dense fiber fill that I had in my double pane windows. It'd still be there but that's more story than necessary. I plan to use a stapler this time to secure the
batting rather than other things like double stick carpet tape etc. The wood is too porous to hold stickum well.
will keep my eye out for deals on rasps.
Glue up should commence fairly soon on this one. I have 2 sides of the flare left to complete.
I gave up on looking for felt. I have some 3/4 medium dense fiber fill that I had in my double pane windows. It'd still be there but that's more story than necessary. I plan to use a stapler this time to secure the
batting rather than other things like double stick carpet tape etc. The wood is too porous to hold stickum well.
Looks like a favorite old JBL design I coveted years ago: It was all horns or a vertical and horizontal one plus something else. An 8 in woofer maybe. I always thought that was the nuts.
But using the fiberfill rather than fiberglass means I can rip it out and remove the staples and live to play another day, if and when it comes to that.
It usually does.
But using the fiberfill rather than fiberglass means I can rip it out and remove the staples and live to play another day, if and when it comes to that.
It usually does.
Glue up continues. This is an odd size for making end caps top and bottom-- just about an inch too big for standard boards. Temporarily, I butt joined some scraps and will maybe practice using a flush trim bit
for the rounded corner molding on the face.
I'm getting to the point where I'd like to have the first listen pretty soon.
But this rascal will be heavy. He may have to sit on the floor on some short feet or spikes. I want to make a stand for the bottom port but
it will have to be sturdy.
The 167e has been test-fitted in the baffle for the t-nuts and the
flare on the cutout is done.
for the rounded corner molding on the face.
I'm getting to the point where I'd like to have the first listen pretty soon.
But this rascal will be heavy. He may have to sit on the floor on some short feet or spikes. I want to make a stand for the bottom port but
it will have to be sturdy.
The 167e has been test-fitted in the baffle for the t-nuts and the
flare on the cutout is done.
I got some good experience with my router.
Since my previous hole cutter made a 4" hole for the _inside_ diameter of the PVC I had, I used the router and a router sled I made from a design by Bill Hylton. The sled is a plexiglass base affixed to the
router frame in place of the manufactured one.
This allowed me to place a trammel point on the base and use a drill
bit is a pin. The diameter of the router bit has to be factored in but I managed to eyeball a good spot to drill the hole for the pin.
I made 2 practice tries-- one going half way and then flipping the
piece and one going all the way through. The single sided circle cut worked much better. I was surprised at how close to zero tolerance I got. A piece of plumbers tape will take up the slight remaining slack.
Tomorrow I hope to get the front baffle secured and the pvc cut to length. Sunday may be the first listen.
Since my previous hole cutter made a 4" hole for the _inside_ diameter of the PVC I had, I used the router and a router sled I made from a design by Bill Hylton. The sled is a plexiglass base affixed to the
router frame in place of the manufactured one.
This allowed me to place a trammel point on the base and use a drill
bit is a pin. The diameter of the router bit has to be factored in but I managed to eyeball a good spot to drill the hole for the pin.
I made 2 practice tries-- one going half way and then flipping the
piece and one going all the way through. The single sided circle cut worked much better. I was surprised at how close to zero tolerance I got. A piece of plumbers tape will take up the slight remaining slack.
Tomorrow I hope to get the front baffle secured and the pvc cut to length. Sunday may be the first listen.
still fiddling
Still fiddling but getting closer.
I made the top and bottom removable at this time sealed with some window insulation foam and screws.
To review:
The box is 36 in x 11 x 11
Driver 15 " down
I followed the method shown in the pdf above in the post from Planet 10 on stuffing: one wall, top and back. Top and back stuffing of 3/4 fiberfill extend down to about 30 in. meaning the driver is in the center of the length of stuffing.
Round PVC bottom mounted vent 4" inside diameter of 1.5 length.
The top and bottom will be changed out and glued in place after the
tuning process is completed.
The build is large for a stand mount but not really large for a floor stander. With feet it could be on the floor but getting the driver positioned higher requires an open-to-the-bottom stand mount.
Still fiddling but getting closer.
I made the top and bottom removable at this time sealed with some window insulation foam and screws.
To review:
The box is 36 in x 11 x 11
Driver 15 " down
I followed the method shown in the pdf above in the post from Planet 10 on stuffing: one wall, top and back. Top and back stuffing of 3/4 fiberfill extend down to about 30 in. meaning the driver is in the center of the length of stuffing.
Round PVC bottom mounted vent 4" inside diameter of 1.5 length.
The top and bottom will be changed out and glued in place after the
tuning process is completed.
The build is large for a stand mount but not really large for a floor stander. With feet it could be on the floor but getting the driver positioned higher requires an open-to-the-bottom stand mount.
together
The build of the single MLTL for the 167e is together. I sealed up the top and bottom as described, tightened all the screws and set it up
on the Workmate(tm) which allows for the port in the bottom and close
to my amp. It's up too high but at least it's sitting there stable.
When I had up on the work table, I listed at the port. Not a long listen but at some music all I could hear at the port was a bit of fluttering.
I don't know if that's a good or a bad thing.
It plays noticeably louder than the 127e on the other channel in a BIB.
I have an A/B switch on this setup to do comparisons.
The build of the single MLTL for the 167e is together. I sealed up the top and bottom as described, tightened all the screws and set it up
on the Workmate(tm) which allows for the port in the bottom and close
to my amp. It's up too high but at least it's sitting there stable.
When I had up on the work table, I listed at the port. Not a long listen but at some music all I could hear at the port was a bit of fluttering.
I don't know if that's a good or a bad thing.
It plays noticeably louder than the 127e on the other channel in a BIB.
I have an A/B switch on this setup to do comparisons.
Still coasting
With this build, I got it off the Workmate and onto a low stand that allows the bottom port to extend through a hole in the top. Stand height is 24 inches.
I said I'm coasting because the overall effect is pleasant to listen to and I can't envision what if anything needs to be done further.
However I still need some guidance on doing the testing using the Marchand software tone generator. Since it is an elephant to move
I'm reluctant to lug it around to a different listening setup where the software is handy.
From above: If all I hear is some fluttering at the vent on the bottom, is that something that indicates the MLTL is tuned?
I thought I had another post here worrying about honkiness from the size of the box. That, to my ears, just hasn't happened.
Visually it is still pretty big for not being on the floor.
Lastly a note on room characteristics.
The only place I have to put the elephant is in a closet.
Wait. The closet has a number of bi-fold doors. Since some have indicated that putting wings on a build are advantageous for the front baffle, I have fooled around with snugging up the bi-fold closet doors to create that effect. I have not settled on if this is an amazing advance in music listening or no. The doors stay wide open and away from the baffle most of the time.
With this build, I got it off the Workmate and onto a low stand that allows the bottom port to extend through a hole in the top. Stand height is 24 inches.
I said I'm coasting because the overall effect is pleasant to listen to and I can't envision what if anything needs to be done further.
However I still need some guidance on doing the testing using the Marchand software tone generator. Since it is an elephant to move
I'm reluctant to lug it around to a different listening setup where the software is handy.
From above: If all I hear is some fluttering at the vent on the bottom, is that something that indicates the MLTL is tuned?
I thought I had another post here worrying about honkiness from the size of the box. That, to my ears, just hasn't happened.
Visually it is still pretty big for not being on the floor.
Lastly a note on room characteristics.
The only place I have to put the elephant is in a closet.
Wait. The closet has a number of bi-fold doors. Since some have indicated that putting wings on a build are advantageous for the front baffle, I have fooled around with snugging up the bi-fold closet doors to create that effect. I have not settled on if this is an amazing advance in music listening or no. The doors stay wide open and away from the baffle most of the time.
Can't recall ever hearing a vent 'flutter', but if the speaker sounds 'right' to you at typical listening distance(s) that's all that matters.
Assuming your closet is a typical one stuffed with clothes/whatever, it's damping early reflections, creating a much better virtual 2pi (half) space loading, i.e. more like a near-field experience. Closing the doors on it just makes it more so.
GM
Assuming your closet is a typical one stuffed with clothes/whatever, it's damping early reflections, creating a much better virtual 2pi (half) space loading, i.e. more like a near-field experience. Closing the doors on it just makes it more so.
GM
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