>100L is large. Sealed box of 20-30 liters would give you most return.
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Hardly. An extra octave is a night and day difference, especially with a second driver/channel. As for a 104.5L tower being large, maybe in jail cell sized room. It's footprint is only ~14.5" x 10" assuming 3/4" construction (~36.83cm x 25.4cm x 1.9cm).
GM
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Hardly. An extra octave is a night and day difference, especially with a second driver/channel. As for a 104.5L tower being large, maybe in jail cell sized room. It's footprint is only ~14.5" x 10" assuming 3/4" construction (~36.83cm x 25.4cm x 1.9cm).
GM
space is relative. you live in suburban GA; i live in Mumbai (bombay) India.
bombay houses 20 million in a space not larger than Brooklyn. yes we live in jail sized cells. some even live in smaller apts.
a colleague of mine just spent the equiv of about US $12,000 for a 380 sq. ft. one room apt which will house himself, wife, 3 kids and ailing mom. this too about 90 min by train from the city center. at $150 per month this apt is 80 months (7 years) earning.
by these standards our apt is large (and we are only 3 plus a maid) - 2 bedrooms about 900 sq. ft. today it would cost about US $ 175,000 and it 45 mins from city center.
a bit more spacious and upmarket, my moms apt is 2200 sq. ft. (3 large bedroms) and lists for about US $ 600,000 in the city center. since my mom lives alone i have taken over the master bedroom to house my audio system. we visit every weekend. my mom gets to play with her grandson, i get to listen to some music, my wife gets to socialise (i am, by her standards, a recluse).
During the week I use my HT/AV system for audio.
before dave (plante 10) pays me a visit I better get back on topic...space as you see is relative.
bombay houses 20 million in a space not larger than Brooklyn. yes we live in jail sized cells. some even live in smaller apts.
a colleague of mine just spent the equiv of about US $12,000 for a 380 sq. ft. one room apt which will house himself, wife, 3 kids and ailing mom. this too about 90 min by train from the city center. at $150 per month this apt is 80 months (7 years) earning.
by these standards our apt is large (and we are only 3 plus a maid) - 2 bedrooms about 900 sq. ft. today it would cost about US $ 175,000 and it 45 mins from city center.
a bit more spacious and upmarket, my moms apt is 2200 sq. ft. (3 large bedroms) and lists for about US $ 600,000 in the city center. since my mom lives alone i have taken over the master bedroom to house my audio system. we visit every weekend. my mom gets to play with her grandson, i get to listen to some music, my wife gets to socialise (i am, by her standards, a recluse).
During the week I use my HT/AV system for audio.
before dave (plante 10) pays me a visit I better get back on topic...space as you see is relative.
What people think about Morell's MW265 woofer (F3=30Hz, Qts=0.44, Vas=88L) with also Morell's MDT20 tweeter (F3=650Hz(, both driver are 90dB@2.38V/m, in 50L vent-box and crossing 2kHz ?
I'd simulate this in Speaker WorkShop, and it looks good, but maybe somebody tried ?
I'd simulate this in Speaker WorkShop, and it looks good, but maybe somebody tried ?
>space is relative. you live in suburban GA; i live in Mumbai (bombay) India.
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Thanks for stating the obvious, though what it has to do with Sébastien in Montreal is beyond me, nor does it shed any light on why you think higher Q drivers are unsuited for vented designs, or how a small sealed cab can compete performance wise with a dual driver pipe.
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>bombay houses 20 million in a space not larger than Brooklyn. yes we live in jail sized cells. some even live in smaller apts.
(snip)
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This is an Indian social problem that's totally irrelevant and well beyond the scope of this thread. All it means to me is that your mother appears to live considerably better than I do and that there doesn't seem to be many folks practicing and/or using effective birth control.
GM
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Thanks for stating the obvious, though what it has to do with Sébastien in Montreal is beyond me, nor does it shed any light on why you think higher Q drivers are unsuited for vented designs, or how a small sealed cab can compete performance wise with a dual driver pipe.
====
>bombay houses 20 million in a space not larger than Brooklyn. yes we live in jail sized cells. some even live in smaller apts.
(snip)
====
This is an Indian social problem that's totally irrelevant and well beyond the scope of this thread. All it means to me is that your mother appears to live considerably better than I do and that there doesn't seem to be many folks practicing and/or using effective birth control.
GM
tool49 said:
Sorry about the delay in responding. I have been really busy for the past few days, and my digital camera has been out for service. I'll try to snap a few pics of my speakers tonight and get them posted here to give you an idea of my final box.
Cheers,
Zach
Thanks GM and navin for clarifying the situation in Bombay. (Don't get me wrong this is not a sarcastic remark, I like learning about other countries. I just wish I could visit them all, but that is more than my budget could ever allow me.) I do have more space than was originally planed, turns out the living room will be 15' x 13' so I definitely can go for bigger speakers.
I received the drivers today, the quality is really nicer than expected, I mean, for $9 each I was expecting something a bit more iffy, but no! I'm out of time right now to do any testing, but I will definitely try a sealed box of 35L and a vented box of 60L and see how I like the sound of each other. Then I'll decide what my final design will look like.
Zach> Take your time, your input will be of great value since you have a working example of something I would like to achieve. I believe the wait is definitely worth it.
nobody special> yeah that's what was meant by Tau ou Phi. Here's the place where I found the most info:
http://www.mcs.surrey.ac.uk/Personal/R.Knott/Fibonacci/phi.html
GM> What exactly is an ML-TL design? How do I model it? Is it reliable enough to just build it and expect good result with a moderate amount of tweaking?
Once again, thanks for everyone's input.
Sébastien
I received the drivers today, the quality is really nicer than expected, I mean, for $9 each I was expecting something a bit more iffy, but no! I'm out of time right now to do any testing, but I will definitely try a sealed box of 35L and a vented box of 60L and see how I like the sound of each other. Then I'll decide what my final design will look like.
Zach> Take your time, your input will be of great value since you have a working example of something I would like to achieve. I believe the wait is definitely worth it.
nobody special> yeah that's what was meant by Tau ou Phi. Here's the place where I found the most info:
http://www.mcs.surrey.ac.uk/Personal/R.Knott/Fibonacci/phi.html
GM> What exactly is an ML-TL design? How do I model it? Is it reliable enough to just build it and expect good result with a moderate amount of tweaking?
Once again, thanks for everyone's input.
Sébastien
Steve> "Did you mean the .62:1:1.62 ratio for enclosures with least standing waves?"
Yes I did.
Equal dimensions are the worst, followed by mutiples of the one dimension.
Golden section is apparently the best - I personally dont have the time & resources to compare with other types of enclosures.
Sebastien - remember when testing your box for bass use a mono signal this will sum both channels so you will get a better idea of whats going on.
Personally I would recommend building pairs of boxes for listening tests.
Yes I did.
Equal dimensions are the worst, followed by mutiples of the one dimension.
Golden section is apparently the best - I personally dont have the time & resources to compare with other types of enclosures.
Sebastien - remember when testing your box for bass use a mono signal this will sum both channels so you will get a better idea of whats going on.
Personally I would recommend building pairs of boxes for listening tests.
OK, enough pictures. I used 3/4" MDF from The Home Depot for all walls. The section where the speakers are attached is double thickness MDF. All the drivers are flush mounted. The total volume of the box is about 143 liters. The calculated volume was 130 L, but I added 10% for bracing and internal padding. The external dimensions are 48" tall, 20 5/8" deep, and 11 5/8" inches wide. There are two 3" diameter ports that are 9 7/8" long. For now the x-over is very simple, and not really optimized for the drivers. I used a 4.7 uF cap in series with the tweeter, and a 0.8 mH coil in series withe the two woofers. These values are a bit of a crap-shoot. (I pulled them out of old JBL SR crossovers). I found that wiring the tweeter in inverse polarity I got a smoother response. The woofers are wired in paralell. With this arrangement, the total sensitivity of the speakers is about 92 dB. Yes, these speakers are tube-friendly. I wanted to place the ports in the back, but this just wouldn't work, as the speakers would be placed against a wall. At least I don't need baffle step compensation.🙂
As for the sound, It's pretty damb good. Even with the x-over being so makeshift it sounds pretty good. I can't believe how much bass these things put out. I have to keep reminding myself that there is no subwoofer running. I had a few friends over when I hooked them up, and they all want a pair.
Now for the things I should have done better: I really should have braced the inner walls better. I think I am losing a fair amount of low energy response through the cabinet walls. Making the walls thicker would have helped this also. One thing I plan to do is add some more sound dampening material to the inside of the cabinet walls. I was planning on using something similar to what is used in the car stereo circles to help deaden car panels. On top of this, I will glue carpet tiles to add mass and to help reduce reflections. On top of all of this, I am going to attatch the Auralex 2" pyramid foam that is in the speakers right now. This should help a lot in tightening up the bass. It should also increase the efficiency slightly since I won't be losing so much energy through the walls.
Finally, I am going to sand the boxes down and finish them. I still can't decide between piano black or a nice wood veneer. I am leaning more and more towards black right now.
Anyway, I hope this helps. I am very happy with these speakers, and considering how little they cost to build, I am even happier. They are rather large, but they sound so good that I don't care. See......My son likes them to.
Cheers,
Zach
As for the sound, It's pretty damb good. Even with the x-over being so makeshift it sounds pretty good. I can't believe how much bass these things put out. I have to keep reminding myself that there is no subwoofer running. I had a few friends over when I hooked them up, and they all want a pair.
Now for the things I should have done better: I really should have braced the inner walls better. I think I am losing a fair amount of low energy response through the cabinet walls. Making the walls thicker would have helped this also. One thing I plan to do is add some more sound dampening material to the inside of the cabinet walls. I was planning on using something similar to what is used in the car stereo circles to help deaden car panels. On top of this, I will glue carpet tiles to add mass and to help reduce reflections. On top of all of this, I am going to attatch the Auralex 2" pyramid foam that is in the speakers right now. This should help a lot in tightening up the bass. It should also increase the efficiency slightly since I won't be losing so much energy through the walls.
Finally, I am going to sand the boxes down and finish them. I still can't decide between piano black or a nice wood veneer. I am leaning more and more towards black right now.
Anyway, I hope this helps. I am very happy with these speakers, and considering how little they cost to build, I am even happier. They are rather large, but they sound so good that I don't care. See......My son likes them to.
Cheers,
Zach
Attachments
WOW!! These are some nice speakers! Thanks this is something similar to what I was planning to build except perhaps for the crossover which will need to be of the second order.
Thanks a lot for taking the time to post all this.
For the wall thickness, perhaps you could just add another ½" veneer-core plywood. That would take care of the finish and definitely add rigidity to you walls.
Now I can't wait to get started on mine.
Sébastien
Thanks a lot for taking the time to post all this.
For the wall thickness, perhaps you could just add another ½" veneer-core plywood. That would take care of the finish and definitely add rigidity to you walls.
Now I can't wait to get started on mine.
Sébastien
GM> What exactly is an ML-TL design?
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For decades they were known as tower, or column, designs, and my preferred cab design if not horn loaded. MJK's research into stuffing effects in TLs led him to develop a very accurate worksheet that's adjustable enough to model the results of them, calling it a MLTQWT (mass loaded tuned quarter wavelength tube). Since a TQWT can also define a TL (transmission line), I've gotten in the habit of calling them ML-TLs.
Anyway, a BR morphs into a mass loaded (the vent) 1/4WL resonator (the cab) as the height:width aspect ratio increases. As this occurs, the positioning of the driver and vent become increasingly more important for the best overall performance over the cab's BW. All BR box calculators assume a uniform particle density so their vent calcs are only ~accurate if the cab is built to a golden or acoustic ratio. Also, with increasing pipe action, the vent requirements change, rendering the standard BR vent calcs much too long.
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>How do I model it?
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AFAIK they can only be modeled in MJK's MLTQWT or BR Mathcad worksheets.
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>Is it reliable enough to just build it and expect good result with a moderate amount of tweaking?
====
It's as reliable as the driver specs used, even more so that the best BR programs IMO since it shows the vent size/length effects on the FR, so if the driver's published specs are 'close enough', then minor stuffing or vent length adjustment is all that's required for the cab portion of the design.
GM
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For decades they were known as tower, or column, designs, and my preferred cab design if not horn loaded. MJK's research into stuffing effects in TLs led him to develop a very accurate worksheet that's adjustable enough to model the results of them, calling it a MLTQWT (mass loaded tuned quarter wavelength tube). Since a TQWT can also define a TL (transmission line), I've gotten in the habit of calling them ML-TLs.
Anyway, a BR morphs into a mass loaded (the vent) 1/4WL resonator (the cab) as the height:width aspect ratio increases. As this occurs, the positioning of the driver and vent become increasingly more important for the best overall performance over the cab's BW. All BR box calculators assume a uniform particle density so their vent calcs are only ~accurate if the cab is built to a golden or acoustic ratio. Also, with increasing pipe action, the vent requirements change, rendering the standard BR vent calcs much too long.
====
>How do I model it?
====
AFAIK they can only be modeled in MJK's MLTQWT or BR Mathcad worksheets.
====
>Is it reliable enough to just build it and expect good result with a moderate amount of tweaking?
====
It's as reliable as the driver specs used, even more so that the best BR programs IMO since it shows the vent size/length effects on the FR, so if the driver's published specs are 'close enough', then minor stuffing or vent length adjustment is all that's required for the cab portion of the design.
GM
Well done.
Nice work usekgb!
Always good to see another project up & running.
As youve discovered bracing & damping is absolutley critical and can give significant improvements in sound quality.
Your idea of using car sound deadening material is a valid.
I used some in my latest, ongoing project, sandwiched between a layer of ply. Certainly helped reduce the panel/wall vibrations.
Keep us informed of your progress.
Nice work usekgb!
Always good to see another project up & running.
As youve discovered bracing & damping is absolutley critical and can give significant improvements in sound quality.
Your idea of using car sound deadening material is a valid.
I used some in my latest, ongoing project, sandwiched between a layer of ply. Certainly helped reduce the panel/wall vibrations.
Keep us informed of your progress.
Time is tough
Sorry for the lack of updates, I am still in the process of building these speakers. Being a student and the semester coming to an end, free time is scarce. I tried the vented vs sealed enclosures and so far I found the vented to sound more like what I wanted.
This monday I just got the wood to build the enclosures which will be around 4ft^3. I'm still debating with myself whether i'll go with a 2 way, 2.5 way or 3 way design of the crossover. I have made provision for extra faceplates so I'll try every configuration and decide which sound the best for my tastes.
Since this is my first project, I decided to go for a type of enclosure that is relatively easy to design, but I've taken good notes for my next project, so all your suggestions are appreciated.
Well thanks once again!
Sébastien
Sorry for the lack of updates, I am still in the process of building these speakers. Being a student and the semester coming to an end, free time is scarce. I tried the vented vs sealed enclosures and so far I found the vented to sound more like what I wanted.
This monday I just got the wood to build the enclosures which will be around 4ft^3. I'm still debating with myself whether i'll go with a 2 way, 2.5 way or 3 way design of the crossover. I have made provision for extra faceplates so I'll try every configuration and decide which sound the best for my tastes.
Since this is my first project, I decided to go for a type of enclosure that is relatively easy to design, but I've taken good notes for my next project, so all your suggestions are appreciated.
Well thanks once again!
Sébastien
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