| edlye |
| Hi, I'm very new to diy loudspeakers and am interested to know if anyone has an idea of which enclosure will suit an Altec 409-8B. The Qts is 1.54, Fs is 91Hz and Vas is 0.61, the speaker was originally designed as a ceiling speaker. OB is not an option because of the lack of WAF. Many thanks! |
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| tubewade |
I would have suggested an OB, probably, but since that's not an option, how about an aperiodic? That high Qts is going to be a killer and your first concern will probably be trying to tame it. You may have to install a damping pad over the back of the driver. I assume that if the WAF doesn't allow for open baffles then a huge 6 cubic foot infinite baffle cabinet would be out of the question too.
Best, Wade |
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| edlye |
| Seems that OB is quite an inevitable choice, what are the options to consider? What about BLH or transmission line? Thanks! |
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| GM |
Greets!
Hmm, these specs are what's listed for the 409-8D, so don't know how accurate this will be, but a ~aperiodic TL is pretty forgiving, so worth a try since it's simple/cheap enough to get a near IB response in a relatively small footprint:
L = 53.183"
W x D = 131.28"^2
All dims i.d.. For WAF, place the vent on the bottom rear, which will have the same 131.28"^2 area. Driver at extreme top and add stuffing until it sounds right to you. Since the driver is going to be up around 49" off the floor depending on how thick a material you use, you may need to make a wedge mounting plate to angle the driver down if you sit fairly close. It's Qts is high enough that a lossy material can be used, so no high $$ plywood/whatever required.
Sim assumes a 1 lb/ft^3 stuffing density using polyfil, so the same amount of acoustic fiberglass insulation will damp out the rest of the ripple.
GM |
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| tubewade |
| I agree with GM. Cheap enough to try and would likely work well. That's what I'd try first. |
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| edlye |
| Imagine my horror when I converted the measurements to metric: 3.33meters x 1.35meters^2. My wife will toss me out of the house if I had that in the living room. :bawling: :D |
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| tubewade |
Wooops! I'm sure she would! There was an error in the math. It shouldn't be that large. I think he meant 135 cm tall with a base foot print of 29.1 by 29.1 cm (847 square cm). If that's not what he meant then GM may to have to elaborate a bit to help my density.
Best, Wade |
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| Geoff H |
Pity about the WAF - OB situ, they go quite well with a bass helper.
Geoff |
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| GM |
| quote: | Originally posted by tubewade
I think he meant 135 cm tall with a base foot print of 29.1 by 29.1 cm (847 square cm). |
No, you got it right, just add the material thickness to all sides. It's just a relatively tall column that can be square, rectangular, whatever since it will be stuffed enough that its shape won't be an issue. Indeed, it's aspect ratio is such that it will need to have wide 'outrigger' mounting legs to make it stable against being accidentally tipped over. |
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| GM |
| quote: | Originally posted by Geoff H
- OB situ, they go quite well with a bass helper. |
Agreed, and its Qts is high enough that the baffle doesn't even need to be all that wide if a decent wide BW woofer is used. |
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| Cal Weldon |
| What about an OB that doesn't look like one and a bass helper on the bottom. Something like this: |
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| GM |
| Yeah, that's what I had in mind. Impressive looking, did you DIY these? BTW, have you gotten the 1803s installed/entertaining your neighbors yet? |
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| Cal Weldon |
Horns are shipped to Sumas Wash. Hopefully pick up July 9.
Yes those are a DIY. Bedroom speakers. |
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| Geoff H |
Nice job Cal. That's the practical way to enjoy OB. True bass on OB needs a wall for the baffle. What freq do they x-over?
This baffle needs assistance under about 120 hz, but I'm still working on the top end.
Geoff. |
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| edlye |
| quote: | Originally posted by Cal Weldon
What about an OB that doesn't look like one and a bass helper on the bottom. Something like this: |
Hi Cal, how do you build one of these? Are there any plans that you can share? Thanks. |
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| edlye |
| quote: | Originally posted by GM
No, you got it right, just add the material thickness to all sides. It's just a relatively tall column that can be square, rectangular, whatever since it will be stuffed enough that its shape won't be an issue. Indeed, it's aspect ratio is such that it will need to have wide 'outrigger' mounting legs to make it stable against being accidentally tipped over. |
Hi GM, I'm a bit confused here, does that mean the enclosure will look like a 3-sided u-shaped 'trough' standing on the long end? Thanks. |
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| edlye |
| quote: | Originally posted by tubewade
Wooops! I'm sure she would! There was an error in the math. It shouldn't be that large. I think he meant 135 cm tall with a base foot print of 29.1 by 29.1 cm (847 square cm). If that's not what he meant then GM may to have to elaborate a bit to help my density.
Best, Wade |
Thanks for the clarification, Wade. I must have made a silly mistake when using an online conversion tool. :dead: But I can't figure out the conversion to get 29.1 by 29.1cm for the W & D. |
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| Cal Weldon |
| quote: | Originally posted by Geoff H
What freq do they x-over? |
it's a 4 way at 100, 1k, 10K all 6dB
| quote: | Originally posted by edlye
Are there any plans that you can share? Thanks. |
No plans as such but they look like this: |
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| tubewade |
| quote: | Originally posted by edlye
Thanks for the clarification, Wade. I must have made a silly mistake when using an online conversion tool. :dead: But I can't figure out the conversion to get 29.1 by 29.1cm for the W & D. |
You're welcome. There are 2.54 cm in one inch. This is where I got 135 cm tall. The footprint would be 847 square cm. The 29.1 cm by 29.1 cm is simply the square root of 847. In actuality, the ratio can be whatever you like that results in an 847 square cm footprint. This is not really a very large enclosure. |
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| GM |
| quote: | Originally posted by edlye
Hi GM, I'm a bit confused here, does that mean the enclosure will look like a 3-sided u-shaped 'trough' standing on the long end? Thanks. |
Greets!
Not any more confused than I am at how you arrived at a three sided 'U' shaped trough from my description of a six sided closed pipe with a driver at one end and a large cutout (vent) at the rear of the other end. I mean a 'U' shape would make it a dipole, not a TL.
GM |
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| GM |
| quote: | Originally posted by Cal Weldon
Horns are shipped to Sumas Wash. Hopefully pick up July 9.
Yes those are a DIY. Bedroom speakers. |
Cool! Pretty awesome for just a bedroom system. |
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| edlye |
| quote: | Originally posted by GM
Greets!
Not any more confused than I am at how you arrived at a three sided 'U' shaped trough from my description of a six sided closed pipe with a driver at one end and a large cutout (vent) at the rear of the other end. I mean a 'U' shape would make it a dipole, not a TL.
GM |
Ha ha, told you I'm new to all this hence the confusion. I'd rather ask and look silly than build wrongly. :D
Ok, it is a 'normal' boxed enclosure with a rear vent at the bottom with the internal dimensions of 135cm x 29.1cm x 29.1cm. How big should the vent be, is it 29.1com x 29.1cm? Are there any internal folds within the enclosure? Thanks. |
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| Cal Weldon |
| quote: | Originally posted by GM
Pretty awesome for just a bedroom system. |
It's my bedroom. :) |
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| Cal Weldon |
If it were me and I had another pair I would really like to hear them OB with a helper woofer. Back when I had those, OB didn't make sense, plate amps weren't yet invented and I no-could afford extra woofer anyway, so I just stuck them in a box. Never did like them.
If you plan on a box, GM's your man to get the best from them.
EDIT: They were my first pieces of Altec. Didn't know what all the fuss was about back then. :) |
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| GM |
| quote: | Originally posted by edlye
How big should the vent be, is it 29.1com x 29.1cm? Are there any internal folds within the enclosure? Thanks. |
Yes, no, you're welcome! |
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| GM |
| quote: | Originally posted by Cal Weldon
It's my bedroom. :) |
OK, I just don't equate 'bedroom' with such a complex, wide BW system since I only do two things there and listening to music isn't one of them ;), but whatever 'floats yer boat'. :) Not knocking it, just surprised. I guess if I'd had bigger bedrooms over the years I might have put bigger ones in though. I did have A7s wedged in mine the last summer I lived at home, but that was a parental mandate. |
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| edlye |
| quote: | Originally posted by GM
Yes, no, you're welcome! |
Hi GM, does the front or rear placement of the vent matter? Would this enclosure be also known as ML TL? Thanks. |
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| GM |
Greets!
No, as I originally stated, I recommended it be on the rear for WAF reasons. I mean a big opening stuffed with insulation wouldn't be acceptable looking to most folks, though of course you could cover it with grill cloth.
No, a MLTL would have a smaller vent to mass load the pipe (TL) to a lower Fp (tuning). With such a high Qts though, this isn't considered the way to best pipe performance, but if you want to experiment with a smaller vent opening you can to see if it sounds subjectively better, though I wouldn't make it < ~52 cm^2.
GM |
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| edlye |
Thanks for your patience, GM!
I'm getting my hands on a pair of Philips AD12202-M8 next week but only have the Fs specs at 45Hz. What enclosure would be good for these drivers? |
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| GM |
You're welcome!
Without specs, don't have a clue........ |
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| edlye |
| quote: | Originally posted by GM
You're welcome!
Without specs, don't have a clue........ |
I just found a spec sheet, but it is in German: http://www.rahaso.de/foren/msg.php?...ange&idx=18657&
Here's a translation with the help of babel fish:
nominal impedance 8ohms
d.c. resistance of the moving coil 6.6ohms
load rating 100W
max load 150W
output 0.5W
resonant frequency 45Hz
through howling tension (lost in translation?) 9V
transmission range 50Hz - 19kHz
magnet material FXD
magnet diameter 124.6mm
magnet mass 990g
energy in the air gap 498mWs
magn. flow density 1110mT
air gap height 8mm
height of the moving coil 9.7mm
minor diameter 35mm
basket diameter 313.3mm
sound opening/free space 278/5mm
depth 135mm
mass of the loudspeaker 1650g
I've also started a new thread for the AD12202 here: http://www.diyaudio.com/forums/show...threadid=104815 |
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