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DIY build - need help/advice


MercedesBerater

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@wvu80  i used 12 bags of the extra-fluff sheet of poly batting.  it looks like what you'd use to make a quilt.  is this ok?  I glued and stapled to the interior walls.

 

should i remove?  or add the open cell foam also?

 

this is what i used - they had it in smaller sections for $4.97 each.  fit each section between bracing absolutely perfect.  used a whole roll folded over itself to size for EACH brace cavity.  6 bags down each side. every wall is covered except the front woofer inner wall. 

image.png.0bde592ca4a03ba5fdd7fafd563c57cd.png

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7 hours ago, MercedesBerater said:

i used 12 bags of the extra-fluff sheet of poly batting.  it looks like what you'd use to make a quilt.  is this ok? 

 

You used polyfil, that's the right stuff.  I've done a few DIY speaker kits but there are many out there who know more than me.

 

7 hours ago, MercedesBerater said:

this is what i used - they had it in smaller sections for $4.97 each.  fit each section between bracing absolutely perfect.  used a whole roll folded over itself to size for EACH brace cavity.  6 bags down each side. every wall is covered except the front woofer inner wall. 

 

It sounds like what you got fit your project perfectly.  Can't ask for more than that.

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On 2/12/2021 at 3:37 PM, capo72 said:

I wrote "not that much more difficult". IMO it's worth the extra effort, but I defer to you, you're the tapped horn expert. I've only built 1. I don't know why I bother offering my opinion anywhere on the internet anymore. This forum, like so many others are so frustrating to me lately. I hate the internet, I think I need a break!

Tapped horns are easy to build, since they use all RIP cuts.

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On 2/17/2021 at 12:04 PM, PrestonTom said:

 

One trick that I have used is to make the cabinet about 10% larger and the port about 10% longer than "necessary". Stuff the cabinet and then run impedance sweeps (google on how to do this). Then start decreasing the length of the port tube until the impedance plot shows that you have "reached" the desired port tuning. It is best to run these sweeps with the cabinet in the approximate position that you will use it (i.e., near a wall or near a corner, etc). The beauty of this is that it takes some of the guess work about internal volume and compensation for drivers, bracing etc.

 

good luck,

-Tom

Excellent advice. Hear hear!

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question -- i am wondering how bad of an idea it would be to remove one of my R-115sw  amp's  (400w-rms)  and connect it to the pair of 18's  just to test them and make sure they move and function.   would it toast the amp trying to move that big of a subwoofer at low level?   2ohm circuit,  doubtful that little amp on the R115 is capable of much below 4ohm ?    

 

thoughts?  

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Well, as long as you don't turn it up very loud, it will be fine.  But lets be honest, no one would ever connect this up and be able to resist the urge to see what it can do!  So, I would say you can rewire the sub temporarily to be at an 8 ohm load. (The 18's are dual 2 ohm voice coils from what I remember when I built mine, correct?... so make each driver a 4 ohm load and then run them in series to achieve a safe 8 ohm load.)

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6 hours ago, MercedesBerater said:

... would it toast the amp trying to move that big of a subwoofer at low level?   2ohm circuit,  doubtful that little amp on the R115 is capable of much below 4ohm ?    

 

thoughts?  

 

1 hour ago, Iteachstem said:

... (The 18's are dual 2 ohm voice coils from what I remember when I built mine, correct?... so make each driver a 4 ohm load and then run them in series to achieve a safe 8 ohm load.)

 

Yes, each Ultimax 18 has 2 voice coils at 2 ohms each, so the safest way to start out, as stated by @Iteachstem, is to wire each driver in series with itself (=4 ohms) and then both drivers in each cabinet in series (=8 ohms total).

 

Start with a single jumper wire from one positive terminal to one negative terminal (of the 2 pairs of terminals on opposite sides of each sub driver), and then connect the 2 woofers in each cabinet in series also.

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2 hours ago, MercedesBerater said:

like this?

 

image.png.b40c7241f19a0d5d47237833c1da9535.png

 

 

 

That is the general idea. The need to do that also depends on the capabilities of the amplifier in use. The important thing is that the amplifier always encounters enough resistance, ohms, that it never trips the protection circuit or melts down when you crank it up. 

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2 hours ago, MercedesBerater said:

I was looking to get the SP1-4000W speakerpower amp,  if i wire in 8ohm instead of a 2ohm configuration -- maybe i don't need such an expensive amp!  maybe i can back off to the SP1-2400  and wire them as 4 ohm? or 8ohm? 

 

The website for that amp doesn't have detailed specs, so I can't say, but something like a Crown pro amp with 2 ohm specs could allow you to wire the drivers for lower ohms, and therefore more available watts.

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I’m looking at either the SpeakerPower 

SP1-4000   (4000 watt at 2ohm, 2000 at 4, etc) 

 

SP1-2400  (2400 watt at 4ohm, 1200 at 8 )

 

 

I figured  the bigger amp with almost double the watts & stable to 2 ohm was the better choice.   But if I wire them as 8 ohm, that becomes totally unnecessary, right?   Or should I just get the bigger Amp and wire them 2ohm? 

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1 hour ago, MercedesBerater said:

They have specs, it’s just under the “technical tab”  not listed in each amp page.   They have a chart.    

 

 Ok now I see. Nice amps. With the SP1-4000 you can wire each of your dual driver cabinets in series/parallel to have a 2 ohm load. There will be a whole lot of shaking going on with 4000 watts!

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WELP,.... i attempted to paint the box myself.   looked pretty good, until it dried. then i saw little pimples start showing up in the paint.  I'm thinking it's dust maybe.  tried to wet-sand it,  and the paint is so thin it's back to primer in a few swipes even with 1,000 grit.  

 

so.... off to the body shop for a quality finish.   updates in a few weeks. (hopefully)

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2 hours ago, MercedesBerater said:

WELP,.... i attempted to paint the box myself.   looked pretty good, until it dried. then i saw little pimples start showing up in the paint.  I'm thinking it's dust maybe.  tried to wet-sand it,  and the paint is so thin it's back to primer in a few swipes even with 1,000 grit.  

 

so.... off to the body shop for a quality finish.   updates in a few weeks. (hopefully)

Why not just Duratex it?

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20 minutes ago, MercedesBerater said:

@CECAA850

 

duratex looks like truck bed liner from the photos i've seen.   too rough and abrasive looking for my tastes. 

 

i'm looking for a glossy piano lacquer type finish.  (similar to what's on the SVS  PB-16Ultra) 

Be prepared to spend some major coin then.  You'll want a primer/basecoat/clearcoat finish then.

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@CECAA850  yes, i already have a few quotes.  i'd rather spend the money and have it look the way i want, versus learning on the job and trying to paint it myself.   

well, i did try it myself - and that sealed the deal to send it to a body shop. 

 

i figure,  i  did everything else in the theater exactly the way i wanted - no sense in half-a$$ing this step.   🤣

 

plus --  i sold my Denali pickup  and my 30 foot Monterey boat this year-- so i have more cushion before the wife gives me the side-eye. 

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