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4-18" Fi Q HT's Project

post #1 of 39
Thread Starter 
I have spoken to many of you before this purchase as to my goals and I appreciate all of your input. My drivers arrived today. 4-18" Fi Q HT's S2. I have a couple other projects that need completed before I begin on this one pushing this to Spring. However I wanted to share my pictures and ideas.









Next to a 12" AA Arsenal



Enclosure: I plan on 4 individual slot ported enclosures under the tv. The enclosures will be 20"(W)x 28"(H)x 25"(D) with a countersunk double baffle. Internal cf before port and driver displacement is 6.45cf. I am still deciding on the tune. I am a little stuck there and need to decide between 17Hz and 20 Hz. I am leaning toward the 20 Hz tune as I listen to a lot of music in comparison to movies. The length of the port tuned to 20Hz is 2x 9"(W)x 3"(H)x 52.2"(L) ~.5cf. The driver displacement is .24cf. Net after port and driver displacement would be 5.71cf. I am not sure if I am going to use dowels or scrap MDF for bracing so I will refrain from trying to estimate the volume they will use. This is as large (W) as I can go and still have room for my mains, which are yet another project in my book. I can increase the height to 30" and increase the gross internal cf to 6.63cf but I don't think there will be any discernible increase in output and would cause the tops of the enclosures to block too much of the windows. I was given clearance to do so, however I don't want to push my luck. smile.gif

Power: As soon as my project funds are replenished I plan on buying the iNuke6000DSP. I chose this option due to the built in DSP and power output. I will be ordering and replacing the stock fans at that time.

AVR: Yamaha RX-V2400. I have considered upgrading this unit, but the budget just isn't there this year. Until then, this will be the AVR.

Sources: PS3 for movies (both DVD and BR) and games. My laptop to stream Pandora and my mp3 collection. and finally the Direct TV HD receiver.

If anything looks off, please feel free to give me input. After learning how to successfully input driver data into WinISD, the program no longer works. I have to force close it when I try to use it. I think I may invest some time into trying another method for modeling. Scott Simonian suggested Unibox. I need to get Excel first. I had it on an older laptop I used in school but it has recently died.

Chris
post #2 of 39
Man those drivers look stout-hot damn!
post #3 of 39
Thread Starter 
Quote:
Originally Posted by gpmbc View Post

Man those drivers look stout-hot damn!

I was thinking the same thing. smile.gif I wish I had one of my older 12" AA Havoc's to put in the picture too but I sold it a few weeks ago. I am really looking forward to building these. I know this is an average everyday build for the folks here, but it is as big as I have ever attempted in a house.
post #4 of 39
subscribed
post #5 of 39
Hey!

Holy crap. This thread totally fell off the radar.

How did this turn out? smile.gif
post #6 of 39
Quote:
Originally Posted by Scott Simonian View Post

Hey!

Holy crap. This thread totally fell off the radar.

How did this turn out? smile.gif

How in the world could it? eek.gif It's your fault Scott biggrin.gif:
post #7 of 39
Thread Starter 
This got put on hold while I build the SEOS12/DNA360/AETD12M mains. I was just researching cabinets and chatting with other members today about some options. smile.gif Time for me to get this rolling again.
post #8 of 39
I am still waiting to see others with FI black frames. They told me all the newer frames are black and I have yet to see any from the HT guys.
post #9 of 39
Thread Starter 
That would be very cool. Although I would never see them once installed.

Notice the AA driver in the picture above did have a black 12spoke. No idea why the AA drivers I have had were all black and the Fi drivers were all silver. I never asked that question.
post #10 of 39
I spoke with Scott a while back and they told me the woofer baskets were going to all be black now. They had a flaking problem with the first batch but now that is taken care off. So I will be ordering in about 2 months a 15 or 2. And since mine is going in a TH I would prefer black if I can. Either way glad to see your build it starting back up again. biggrin.gif
post #11 of 39
Thread Starter 
It is those little touches that can sometimes make all the difference. smile.gif
post #12 of 39
Thread Starter 
I unburied the 18"s today. I had a spectacular fall at a restaurant a couple weeks ago, so as usual things are going at a snails pace. I am discussing my enclosure options with a few others via PM. I will be able to pick up the material needed for the enclosures after Oct1 although I will be waiting on power. One step at a time. smile.gif I am going to measure my maximum space and figure out from there what to do about specifics. So here is where I am at for now.

post #13 of 39
Thread Starter 
I have 45" of width, 36.5"(Height of center channel) of height, and would like to keep the depth to 22-24". So I wasn't too far off with my initial measurements in the first post. So for all intensive purposes each cabinet 22-22.5" wide, 36.5" high, and 24" deep. So using the maximum dimensions I have a gross of 9.57cf to work with per cab. As some of you may know my inspiration for this build is Archaea's Captivator thread. I have looked at JTR's site and tried to come up with a guess on their enclosure but have been unable to fit the port at 17.5Hz, and the required ~6cf airspace for the driver in within the outer dimensions they have listed. These are my target numbers that were recommended by Fi.

If anyone would like to take a stab at running through some options with me, that would be awesome. My concern is port noise. and I have had no luck with Win ISD in trying to model.

Enclosure: 24" x 22.5" x 36.5" = 9.5703cf gross

Here is what I have experimented with for ports:
21" x 2" @ 17.5Hz = 33.2707" taking 0.8087cf leaving 8.7613cf net. Less .24cf for driver displacement = 8.5213cf

21" x 3" @ 17.5Hz = 51.3784" taking 1.8732cf leaving 7.6968cf net. Less .24cf for driver displacement = 7.4568cf

21" x 4" @ 17.5Hz = 69.6749" taking 3.3869cf leaving 6.1831cf net. Less .24cf for driver displacement = 5.9431cf

Although this doesn't include any bracing, with this sized enclosure it seems I can come close to my target with any of these options. Is there a way to verify the best option as far as port velocity is concerned? These drivers should model very similarly to the standard Q.

Edit: I am going to run all those again but doing 19.5" wide instead of 21". This is just for perspective as this is what I did with the enclosures for my mains.
post #14 of 39
This site has a calculator for minimum port area. I don't know the stroke of those drivers or I would plug in the numbers for you.
post #15 of 39
hey bud, is the problem with winisd entering the parameters or something else?
post #16 of 39
those:


in this:
http://www.avsforum.com/t/1489541/large-ported-dayton-ho18s#post_23711186


give this:


it's the attack of the marty sub again!

as for the port, i think we ended up at 2.5" height in the marty, but that was before research showing the end correction for slot ports chops off a significant amount of their length. doing it over, i'd say go to a 3" or 3.5" port as the length will fit no problem. for a slot port, my best guess is to chop off about 15% of the projected length in winisd to get to the actual required build length for a given tuning.




Edited by LTD02 - 9/19/13 at 6:27pm
post #17 of 39
Quote:
Originally Posted by LTD02 View Post


as for the port, i think we ended up at 2.5" height in the marty, but that was before research showing the end correction for slot ports chops off a significant amount of their length. doing it over, i'd say go to a 3" or 3.5" port as the length will fit no problem. for a slot port, my best guess is to chop off about 15% of the projected length in winisd to get to the actual required build length for a given tuning.

Winisd calculates rectangular port length correctly. However, it assumes that the inside end of the port doesn't share a wall or 3 with the outside of the box. It's well known on the DIY bass cab forums, since we use a lot of slot ports, that winisd is no good for slot ports.

The link I posted 3 posts up has an option for slot port that takes this into account.
post #18 of 39
Thread Starter 
Quote:
Originally Posted by nograveconcern View Post

This site has a calculator for minimum port area. I don't know the stroke of those drivers or I would plug in the numbers for you.

Nice! Thanks for the link. Bookmarked it too.
post #19 of 39
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

hey bud, is the problem with winisd entering the parameters or something else?

I managed to enter a new drivers parameters but when I tried to cycle to another window the program would freeze. I have down loaded a copy of Excel and Unibox but haven't had the time to sit down and go through that program yet.
post #20 of 39
ah, I see.
post #21 of 39
"Winisd calculates rectangular port length correctly. However, it assumes that the inside end of the port doesn't share a wall or 3 with the outside of the box. It's well known on the DIY bass cab forums, since we use a lot of slot ports, that winisd is no good for slot ports."

well known? ok.

"The link I posted 3 posts up has an option for slot port that takes this into account."

it is well known that slot ports can share 1, 2, or 3, walls with inside of the sub and depending on how the sub is placed in room, 1 and perhaps a second on the outside, thus having a single correction for "slot" vs. "no slot" port is no good. :-)~
post #22 of 39
this guy has performed a study on effective end correction and got multiplier effects ranging from 49% to 82% in just one rather small study, so end correction really is all over the map: http://www.troelsgravesen.dk/vent_tuning.htm
post #23 of 39
and of course there are questions about what correction factor (k) to use:



http://www.ctc-dr-weber.de/speaker/PortCorrection.jpg
post #24 of 39
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

those:


in this:
http://www.avsforum.com/t/1489541/large-ported-dayton-ho18s#post_23711186


give this:


it's the attack of the marty sub again!

as for the port, i think we ended up at 2.5" height in the marty, but that was before research showing the end correction for slot ports chops off a significant amount of their length. doing it over, i'd say go to a 3" or 3.5" port as the length will fit no problem. for a slot port, my best guess is to chop off about 15% of the projected length in winisd to get to the actual required build length for a given tuning.




Yeah man! I was following that and just read through it again. I need to shrink that enclosure down a bit though as I don't have enough room for one quite that large. Given my size constraints and using the calculator provided by nograveconcern, the length for the 21" x 4" port was cut from ~69" down to ~59". Using your suggestion of subtracting 15% from my calculations I get almost dead on the same thing. smile.gif

In either case it brings the port displacement down to 2.8680cf from 3.3869cf respectively. Leaving 6.462 net less bracing when considering the 4" option. Pretty much dead nuts on what I was looking for.

Is 4" too large? I wanted to do a multiple of the ports on the mains for aesthetics, but only if it is not detrimental to the project.
post #25 of 39
Quote:
Originally Posted by LTD02 View Post

"Winisd calculates rectangular port length correctly. However, it assumes that the inside end of the port doesn't share a wall or 3 with the outside of the box. It's well known on the DIY bass cab forums, since we use a lot of slot ports, that winisd is no good for slot ports."

well known? ok.

"The link I posted 3 posts up has an option for slot port that takes this into account."

it is well known that slot ports can share 1, 2, or 3, walls with inside of the sub and depending on how the sub is placed in room, 1 and perhaps a second on the outside, thus having a single correction for "slot" vs. "no slot" port is no good. :-)~

Bolded part is what is well known elsewhere. I'm not saying it to be argumentative, but every slot port thread goes into talking about port length calculations in Winisd, which doesn't work. It doesn't work because it doesn't attempt to calculate a slot port of any kind. I'm trying to get that well known here. wink.gif

The link assumes 3 walls and gets you close. Building a slot port box to an exact tune in an iterative process. You have to build, measure, adjust.

Thanks for the links to the studies.
post #26 of 39
^^ interesting #24 & #25. :-)

the only potential problem of a port that is too large is that it has too be too long.

too long of a port will lower the first resonance into the pass band and create a hiccup in the frequency response.

for a sub that will be crossed at 80, a good rule of thumb is to keep the first resonance up around 160hz or higher, so it doesn't enter the passband and that generally means a port with a length of around 3 feet or so.

the larger the port, the longer that it must be for the same tune, so to get the port down to around three feet long or so, either make it slightly more narrow or make the box a lot larger.

marty attacks. :-)~

post #27 of 39
Thread Starter 
I am going to have to process this in the morning. smile.gif I will run the numbers again for 19.5" and re calculate with both 3" and 3.5" of height.

Do you have a good explanation of a first port resonance?

Thank you both for your input!
post #28 of 39
Quote:
Originally Posted by filtor1 View Post

Yeah man! I was following that and just read through it again. I need to shrink that enclosure down a bit though as I don't have enough room for one quite that large. Given my size constraints and using the calculator provided by nograveconcern, the length for the 21" x 4" port was cut from ~69" down to ~59". Using your suggestion of subtracting 15% from my calculations I get almost dead on the same thing. smile.gif

In either case it brings the port displacement down to 2.8680cf from 3.3869cf respectively. Leaving 6.462 net less bracing when considering the 4" option. Pretty much dead nuts on what I was looking for.

Is 4" too large? I wanted to do a multiple of the ports on the mains for aesthetics, but only if it is not detrimental to the project.

21x4 is about perfect for that driver...except that it's too long as LTD02 has stated.

So to get port length under 36" you can:

make the box bigger

tune higher

under-size the port

user a driver with less throw
post #29 of 39
Thread Starter 
Here is the 19.5 calculations:

19.5" x 3" @ 17.5Hz = 47.4789" taking 1.6074cf leaving 7.9627cf net. Less .24cf for driver displacement = 7.7227cf.

End correction of 15% = length of 40.3571"

19.5 x 3.5" @ 17.5Hz = 52.5500" taking 2.0755cf leaving 7.4945cf net. Less .24cf for driver displacement = 7.2545cf

End correction of 15% = length of 44.6675"

Changing the tuning to 20Hz:

19.5" x 3" @ 20Hz = 34.8714" taking 1.1805cf leaving 8.3896cf net. Less .24cf for driver displacement = 8.1495cf

End correction of 15% = 29.6407"

19.5" x 3.5" @ 20Hz = 41.2296" taking 1.6284cf leaving 7.9416cf net. Less .24cf for driver displacement = 7.7016cf.

End correction of 15% = 35.0452"

It looks like I may have to tinker with the tuning and not go as low as the Caps to avoid the first port resonance issue and still keep air speed under control as well.

Is the first calculation here pushing my luck at ~45" using the 19.5" x 3.5"? I feel like I am close

I have been referencing this thread as well. http://www.avsforum.com/t/1018171/18-easy-button-end-tables-24-x-21-x-36-hwd smile.gif Although it doesn't seem to address the issue of first port resonance (76" port length), it does get my brain fired up.
Edited by filtor1 - 9/20/13 at 9:38am
post #30 of 39
Here is a thread that talks about port resonance. From what the thread is saying, you wouldn't want the port to be any longer that that 40". Shorter would be better.
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