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MercedesBerater

DIY build - need help/advice

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I am trying to model a subwoofer box before i undertake a DIY build.

 

I have added a UM18-22 into WinISD 

 

I am trying to model sealed vs. ported for the left and right front corner locations in my HT. 

I want to build a stack of four UM18-22 in each corner.  Box dimensions roughly 22'' wide, 22'' deep, 7 feet tall.  (~22 cu/ft)

Basically - trying to build the Seaton F18's (stack of 4) for fraction of the cost.

 

When I graph out the sealed box - and the ported box (both same box dimensions) they don't graph much different. 

Is this abnormal?  I expected a box with 4 drivers, this big and ported would be 'off the charts' so to speak. 

 

they both peak at 35hz and then begin to roll off, almost identical slopes even, except the ported is 1.85db higher output at 35 hz. 

 

something can't be right.  If this is the case, i would totally build it all sealed just for simplicity sake - just mimic the Seaton F18 dimensions and be done with it.

 

any help-thoughts-insight? 

 

(ported box square vent =  18" wide x 4"tall x 35.54" length (last value won't let me change it)  

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50 minutes ago, MercedesBerater said:

When I graph out the sealed box - and the ported box (both same box dimensions) they don't graph much different. 

Is this abnormal?  I expected a box with 4 drivers, this big and ported would be 'off the charts' so to speak. 

Yes, that's abnormal.  The sealed box frequency response will show a long gradual roll off.  The ported box will model flatter till you hit the tuning frequency.  There it will have a slight rise than fall off sharply.

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@CECAA850    If you were doing a build with 4 drivers, basically a box floor to ceiling (in the corners)  would you go ported or sealed?   seems like ported is the no brainer since i have about 22cu.ft of volume -  i'm just a bit nervous about the complexity of figuring out the slot port length. 

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@henry4841  thank you for the link !    that site says i should be building SEALED with that driver,  it says not recommended as ported.  Guess that's why the Seaton F18 (same driver)  is just a sealed box, simple...

 

I didn't want to build a bunch of identical boxes to the Seatons - because i'm worried about stacking 4 subs high, and then they vibrate and topple over like a scary Jenga game.

I'd rather build one massive box and have basically a Stonehenge monolith in the corners.  :) 

 

Essentially - i want this... just don't want to spend $12,000 to get it.  I'm sure i can DIY for a few grand. 

Image result for seaton F18

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26 minutes ago, MercedesBerater said:

@CECAA850    If you were doing a build with 4 drivers, basically a box floor to ceiling (in the corners)  would you go ported or sealed?   seems like ported is the no brainer since i have about 22cu.ft of volume -  i'm just a bit nervous about the complexity of figuring out the slot port length. 

What is the desired Fs?  HT or music?

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@CECAA850  i'm 75%movies & 25% music (CD 100% of the time i listen to music)   also note, when i listen to music, it's typically turned up with the theater door open so i can hear it in  other areas of basement - so sound quality isn't paramount. i use it as a giant boom-box.  

 

the driver Fs is  19.5hz   (Dayton Audio  UM18-22)

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did you consider searching for used deals ----on subs ---

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1 minute ago, MercedesBerater said:

the driver Fs is  19.5hz 

I was asking about the desired Fs of the box if ported.

 

 

Sealed is easy.  The driver manufacturer will give you the cu ft required per driver.  They also would provide ported info if applicable in the future if you ever need it..

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28 minutes ago, MercedesBerater said:

I'm sure i can DIY for a few grand. 

Would be a fun project.

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@CECAA850  ohh, i'm not sure.  I'm trying to rapidly learn all these Alphabet soup letters and meanings and calculations.   I thought with WinISD i could input the driver & dimensions and it would say 'hey, for 22 cu/ft,  4 drivers, you need a XYZ sized port) 

 

maybe i'll stick with sealed & just base it off the 4-6cu/ft ideal range Dayton specifies and adjust the box dimensions accordingly.  That's way easier. 

 

@RandyH000   yes, i'm sure there are good deals out there on used - but there's something to be said for figuring it all out, building it, and saying 'i built that'   

and to get it to fit perfectly in my space - and the look i want - i'll probably never find used. 

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4 minutes ago, MercedesBerater said:

maybe i'll stick with sealed

If the manufacturer stated that the driver is for sealed applications only, don't even consider porting it.

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5 minutes ago, MercedesBerater said:

but there's something to be said for figuring it all out, building it, and saying 'i built that'   

and to get it to fit perfectly in my space - and the look i want -

That's what DIY is all about.

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28 minutes ago, MercedesBerater said:

 

but there's something to be said for figuring it all out, building it, and saying 'i built that'   

 

You're right ,  sometimes , nothing beats a custom build -

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9 hours ago, MercedesBerater said:

@henry4841  thank you for the link !    that site says i should be building SEALED with that driver,  it says not recommended as ported.  Guess that's why the Seaton F18 (same driver)  is just a sealed box, simple...

I have read that about the Ultimax drivers before, but there are a lot of ported designs out there using those drivers. Several versions of the Marty come to mind.

Not sure who is right. I enjoy DIY audio because I like to build things but you can also run into a lot of misinformation from self proclaimed experts.

This may be an example of that. 🙂

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@MookieStl  i noticed that too - all GSG stuff is ported, and i believe all has a recommended UM18 as driver listed.   - sealed is easier to build anyway.  i'm not entirely sure i would be missing anything earth shattering going 3-4 sealed 18's in the front corners and a couple in the rear to smooth out the room response  VS.  a stack of ported.  improvement? yes, i'm sure - worth the effort and mental headache & loss of clean lines? probably not  in my opinion. 

 

and- if i hate it, not too hard to disassemble and start over.  MDF is cheap.  🤣

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Parts Express says that the UM18-22 18" Ultimax can be used for both sealed and vented enclosures.

 

Not the 18in, but for the 15in, Bill Fitzmaurice recommends it as the premium driver for his 24 inch Tuba...

"The RSS 390-HF-4 lacks a gasket on the front of the frame, so if you order it get speaker gasket tape as well.
An inexpensive choice is the Dayton DCS 385-4, a premium driver is the Ultimax 15."
 
I was going to go with the Ultimax 15 for the empty Tuba TH that I just bought, but they are out of stock, as was the RSS 390-HF.
Solen had one RSS 390-HF in stock, so I went with it.
 
 

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if i get the green light from wife - i'll start a build thread.  i had one for my theater years ago - and that was fun to document. 

 

  • Haha 2

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15 minutes ago, MercedesBerater said:

if i get the green light from wife -

 

wait for Valentine's Day  ,  and don't forget the Chocolate and the Flowers -

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If you don't already have the drivers, I would be considering tapped horn subwoofers. You are allocating a large space for them to occupy already. You will get a lot more bang for your buck with tapped horn, and the builds are not that much more difficult.

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