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  #31 (permalink)  
Old October 24, 2010, 06:53 PM
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Originally Posted by vulcan500rider View Post
Thanks as well for the info on lining a ported box; that's what I was working toward--I wasn't sure how one could fill the speaker, if you have a port to worry about.

To answer your question, and clarify my thoughts, I'm unsure where to locate the port itself. I've got the basic design for the MT, upon which I've based my own boxes, but none of the designs I've seen actually show the port. There certainly isn't room to locate it in the front, as I would with a sub, so do I put it in the back, above where I locate the binding posts? I get the feeling putting it under the posts (and thus straight across from the woofer) could be a mistake.

Thanks again,

Sean

EDIT: Oh, and sorry if it seems like I'm sometimes hijacking your thread; it isn't intentional--I just get excited <laugh>
or thought of passive design instead of ported

for ported gives that so low note that you feel and not rich tone of passive
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  #32 (permalink)  
Old October 25, 2010, 05:59 AM
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Originally Posted by 3.0charlie View Post
Reading all this got me thinking, and I've decided to look into building my own enclosures. After much reading from the various sites linked in this thread (thanks to all), here is the (final?) result...
Who's design is that? Hardly any 4-ways out there. The MTM spacing looks pretty big and I'm not sure what that 8" is doing there. Are those the HiVi drivers?... only yellow ones I've seen. Got a link?

[edit]Vulcan, I did post a reply to your post#29... but seems to have gone missing. The HWC site was acting up then so I guess it never got posted, I'll get on writing another reply [edit]
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  #33 (permalink)  
Old October 25, 2010, 06:26 AM
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Originally Posted by vulcan500rider View Post
Gotcha. I was kinda taking the same train of thought so far as porting goes; I figured that if I build with ports, I can always stuff them full if I don't like the sound. I didn't know about the phase difference, however, but I'm not sure it will be a huge deal with surrounds...again, though, I can always go for the trial and error solution.
Typically surrounds are built sealed for a few reasons. They're smaller and easier to find and optimal place for. Usually the recaiver is set to 'small' so all the bass that the port would have otherwise given you is cutout anyway. If you do decide to run a ported box FL there are a few things to consider. Below the tuning frequency of the port the box effectiveness gets less and less and way below the tuning frequency the speaker will act as if there is no box at all and flop around like crazy. Since movies have a lot of low bass and infrasonic bass you would/should still need a subsonic filter. If those subsonic frequencies got to the ported speakers with any kind of power the speakers will physically damage themselves. Not trying to discourage you from building the ported designs, just giving you a heads up on any potential issues.

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Originally Posted by vulcan500rider View Post
To answer your question, and clarify my thoughts, I'm unsure where to locate the port itself. I've got the basic design for the MT, upon which I've based my own boxes, but none of the designs I've seen actually show the port. There certainly isn't room to locate it in the front, as I would with a sub, so do I put it in the back, above where I locate the binding posts? I get the feeling putting it under the posts (and thus straight across from the woofer) could be a mistake.
Ports technically can go anywhere but there a few rules of thumb. Keep the end of the port (on the inside of the box) atleast 1 port diameter away from any surface but a little more is better. Don't put the port directly behind the woofer. More of the midrange - which you don't want - will bounce it's way out the port. Typically the post is put on the back of the speaker to minimize hearing the leaked midrange as well as if you get any chuffing of the port.

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Originally Posted by vulcan500rider View Post
EDIT: Oh, and sorry if it seems like I'm sometimes hijacking your thread; it isn't intentional--I just get excited <laugh>
No worries about any hijack. Point of this thread is to get some more interest going for DIY speakers.
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  #34 (permalink)  
Old October 25, 2010, 08:08 AM
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Who's design is that? Hardly any 4-ways out there. The MTM spacing looks pretty big and I'm not sure what that 8" is doing there. Are those the HiVi drivers?... only yellow ones I've seen. Got a link?
My design, it's a 3-way, and I may drop the 8" driver and only keep the 12" on the bottom.

Yup, they are Hi-Vi drivers. A local reseller has 'em in stock (Solen Electronique Inc.).
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Old October 25, 2010, 01:44 PM
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Originally Posted by 3.0charlie View Post
My design, it's a 3-way, and I may drop the 8" driver and only keep the 12" on the bottom.

Yup, they are Hi-Vi drivers. A local reseller has 'em in stock (Solen Electronique Inc.).
Yeah Solen's where I get most of my stuff.

Keep us up to date on how it's coming!
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  #36 (permalink)  
Old October 25, 2010, 04:46 PM
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Originally Posted by biff View Post
Typically surrounds are built sealed for a few reasons. They're smaller and easier to find and optimal place for. Usually the recaiver is set to 'small' so all the bass that the port would have otherwise given you is cutout anyway. If you do decide to run a ported box FL there are a few things to consider. Below the tuning frequency of the port the box effectiveness gets less and less and way below the tuning frequency the speaker will act as if there is no box at all and flop around like crazy. Since movies have a lot of low bass and infrasonic bass you would/should still need a subsonic filter. If those subsonic frequencies got to the ported speakers with any kind of power the speakers will physically damage themselves. Not trying to discourage you from building the ported designs, just giving you a heads up on any potential issues.



Ports technically can go anywhere but there a few rules of thumb. Keep the end of the port (on the inside of the box) atleast 1 port diameter away from any surface but a little more is better. Don't put the port directly behind the woofer. More of the midrange - which you don't want - will bounce it's way out the port. Typically the post is put on the back of the speaker to minimize hearing the leaked midrange as well as if you get any chuffing of the port.



No worries about any hijack. Point of this thread is to get some more interest going for DIY speakers.
Thanks again. I don't think the subsonic frequencies should be an issue; these have a similar XO to the MTM version, which should take care of filtering anything unsuitable out, shouldn't it? The designer didn't suggest any changes to XO from the sealed to the ported either; he just noted that the richness of the bass increased with the port.

Cheers for the advice on where to put the port, as well. I was pretty sure placing it behind the woofer would be a mistake, but I wasn't sure exactly where I could put it successfully...
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  #37 (permalink)  
Old October 25, 2010, 08:54 PM
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I don't think the subsonic frequencies should be an issue; these have a similar XO to the MTM version, which should take care of filtering anything unsuitable out, shouldn't it?
Nope, no subsonic filtering in the XO. I don't know how movie soundtracks are mastered so maybe they apply a subsonic filter to surround channels? I don't know. Your receiver may have it built in too without you knowing. Agian I'm not saying it "IS" going to be a problem, just letting you know to look out for it because if there is no protection (somewhere along the signal chain) then it can destroy the drivers in short order...

BTW if you want to play with box tunings download a program called WinISD (get the alpha pro version). You may have to creat a new file for you drivers (DC130's aren't they?) if they already aren't in the library. Get the data off the manufacturers spec sheets. Entering driver data can throw can spit out a lot of errors, as you enter data the software calculates other parameters and if those parameters are on the spec sheets and you enter it and they are off (be it rounding errors or what ever) you will get an error. I can't remember off the top of my head what ones to let WinISD calculate but if you have problems let me know and I'll look into it further.
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  #38 (permalink)  
Old October 26, 2010, 06:50 PM
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Nope, no subsonic filtering in the XO. I don't know how movie soundtracks are mastered so maybe they apply a subsonic filter to surround channels? I don't know. Your receiver may have it built in too without you knowing. Agian I'm not saying it "IS" going to be a problem, just letting you know to look out for it because if there is no protection (somewhere along the signal chain) then it can destroy the drivers in short order...

BTW if you want to play with box tunings download a program called WinISD (get the alpha pro version). You may have to creat a new file for you drivers (DC130's aren't they?) if they already aren't in the library. Get the data off the manufacturers spec sheets. Entering driver data can throw can spit out a lot of errors, as you enter data the software calculates other parameters and if those parameters are on the spec sheets and you enter it and they are off (be it rounding errors or what ever) you will get an error. I can't remember off the top of my head what ones to let WinISD calculate but if you have problems let me know and I'll look into it further.
Ooo...I guess I'm going to have to look into that, then...Maybe the manual for my receiver has that info...I would hate to destroy the drivers...

Thanks for the tip on WinISD, as well; I'll have to give it a try.

Sean
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Old October 27, 2010, 10:04 PM
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Ooo...I guess I'm going to have to look into that, then...Maybe the manual for my receiver has that info...I would hate to destroy the drivers...

Thanks for the tip on WinISD, as well; I'll have to give it a try.

Sean
Sean,

Sorry I was too focused on getting the subsonic -don't wreck your speakers- point across I only focused on the bad points of ported designs WRT HT, there is a plus side. Porting the boxes will make the driver play lower (obviously) before it starts rolling off. If your drivers are capable of playing lower and if your receiver has an adjustable crossover, then you can set that crossover lower which has a couple benefits. Each channel will sound 'fuller' and your sub will be playing less of the higher frequencies which makes it less 'locatable', as in you just have bass - and you can't hear that the sub is 'right there'.

I'll post up some graphs though showing what I was talking about sealed vs. ported concerning low frequencies. The HDD on my garage computer (where I had all my modeling software) crashed a couple days ago so I'm just getting it set back up... and my internet's been a bit iffy the last day or so, so it may take a couple days to get it up.

BTW do you already have the parts for the surrounds? and if so were you going TM or MTM?
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  #40 (permalink)  
Old October 28, 2010, 06:00 AM
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Sean,

Sorry I was too focused on getting the subsonic -don't wreck your speakers- point across I only focused on the bad points of ported designs WRT HT, there is a plus side. Porting the boxes will make the driver play lower (obviously) before it starts rolling off. If your drivers are capable of playing lower and if your receiver has an adjustable crossover, then you can set that crossover lower which has a couple benefits. Each channel will sound 'fuller' and your sub will be playing less of the higher frequencies which makes it less 'locatable', as in you just have bass - and you can't hear that the sub is 'right there'.

I'll post up some graphs though showing what I was talking about sealed vs. ported concerning low frequencies. The HDD on my garage computer (where I had all my modeling software) crashed a couple days ago so I'm just getting it set back up... and my internet's been a bit iffy the last day or so, so it may take a couple days to get it up.

BTW do you already have the parts for the surrounds? and if so were you going TM or MTM?
No parts yet, just the boxes themselves (no ports drilled, b/c I haven't got them for exact sizing). The boxes are the TM design, though. It's funny, though; having made them (I hope) according to Curtis' design, they're actually deeper and wider than the MTMs, just not as tall. I don't have any pics of the finished boxes yet, but here's the face (primed, not painted):
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