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Subwoofer Building Questions
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Old 21st July 2018, 09:59 PM   #31
aslepekis is offline aslepekis  United States
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Quote:
Originally Posted by WillHoog View Post
I want as little white noise as possible... Would this setup cause it?
I have no reason to think there would be an inherent amount of objectionable noise to that equipment chain, but there will also be at least six separate level controls, so you will need to pay attention to gain structure otherwise the system can easily become noisy even if the equipment itself is very quiet.
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Originally Posted by WillHoog View Post
That is the correct signal flow, but keep in mind that that miniDSP you linked has unbalanced RCA inputs and outputs, so you will need adapters between it and your mixer as well as it and your JBL's. That Pyle amplifier has RCA inputs so you wouldn't need an adapter there.

Also, I would not be surprised if Pyle wasn't being truthful about that units power output. that doesn't necessarily mean it won't have enough power for your needs, just that I doubt that it's actually 120 watts.

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Originally Posted by WillHoog View Post
(btw I was asking that one question as confirmation and it was cleared up in the next response)
Then you're progressing in understanding this, that's excellent. But I apologize for being redundant.
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Old 22nd July 2018, 12:24 AM   #32
WillHoog is offline WillHoog  United States
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Quote:
Originally Posted by aslepekis View Post
Also, I would not be surprised if Pyle wasn't being truthful about that units power output. that doesn't necessarily mean it won't have enough power for your needs, just that I doubt that it's actually 120 watts.
Yeah so I will have 50 - 60 watts headroom for any false advertising...

I can't find any miniDSPs with 1/4 connection, tbh thought those were 1/4 connections but I couldn't find any info saying what connection it really was. I would be fine with the adapters as long as they don't make the quality worse.
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Old 22nd July 2018, 12:52 AM   #33
aslepekis is offline aslepekis  United States
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Originally Posted by WillHoog View Post
I can't find any miniDSPs with 1/4 connection, tbh thought those were 1/4 connections but I couldn't find any info saying what connection it really was. I would be fine with the adapters as long as they don't make the quality worse.
MiniDSP doesn't have any models that use a 1/4" connector (as far as I know anyway). This one has balanced connections, it just uses Phoenix connectors rather than TRS or XLR. But as I said earlier, I haven't personally had issues with mixing balanced and unbalanced.
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Old 22nd July 2018, 01:56 AM   #34
WillHoog is offline WillHoog  United States
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Ok it seems I have all the amps and crossovers understood and picked out. Now back to building the subwoofer.

I posted screenshots of the design and I still should do all the exact calculations (taking away wall volume and bracing volume) to get the right volume for the right port length and diameter. Btw should I take away the volume of the woofers themselves? I don't see their volume in the product details...

I remember people saying to use something like pvc pipe for the ports, how exactly would I get pvc the exact right diameter and length and have 1 flared end?

Also I would like some clearance on what insulation/foam I should buy. Is this simple stuff or should I read about it? Videos were putting foam inside the bracing, I think these were for closed boxes though.
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Old 24th July 2018, 02:13 AM   #35
hollowboy is offline hollowboy  Australia
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Quote:
Originally Posted by WillHoog View Post
I posted screenshots of the design and I still should do all the exact calculations (taking away wall volume and bracing volume) to get the right volume for the right port length and diameter. Btw should I take away the volume of the woofers themselves?
Yes. But don't worry about making it 'exact'. If 100 litres is 'perfect', then you add 15 litres to account for bracing & drivers, it won't matter it that's 3 litres more than necessary.

The screenshots look fine, by the way. A very minor (but free) improvement: run the braces slightly to one side, rather than right down the centre of the panels. Asymmetry is good.

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Originally Posted by WillHoog View Post
I remember people saying to use something like pvc pipe for the ports, how exactly would I get pvc the exact right diameter and length and have 1 flared end?
Use anything rigid for the ports. Stiff cardboard tubes are fine.

Ports don't have to be cylinders. You can make square ports from scrap MDF.

They don't have to be 'exact'. If the simulator suggests a port of 46.72mm diameter, 50mm diameter is fine. You'd just make the 50mm port slightly longer to keep the same tuning.

If you do 'flanged and flared' ports like in the link, you can do the flaring with almost anything. A file & sandpaper would work. If the point of flaring is to reduce turbulence, then you should flare both ends.

vent tuning

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Originally Posted by WillHoog View Post
Also I would like some clearance on what insulation/foam I should buy. Is this simple stuff or should I read about it? Videos were putting foam inside the bracing, I think these were for closed boxes though.
Ported boxes use relatively little stuffing.

Don't buy special acoustic foam. Buy yourself a new pillow, and use the grody old one to stuff your speakers.
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Old 24th July 2018, 04:46 AM   #36
WillHoog is offline WillHoog  United States
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If it makes a good difference I will try but I think making the bracing uneven would complicate doing the measurements and cuts by a lot...

Right now I have a Vb of 180 put into the program. I am fine with the Fr anywhere with a Vb of 150 to 180. The thing is that the port length changes up to 10cm longer in that range. With the size of my box, how much should I approx take off the 180 to get a good acurate length?

Btw I'm building a recording booth for some people I'm working with and will be left with 3 extra 12" by 12" acoustic foams. This might not be enough to work with though.
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Old 24th July 2018, 11:05 AM   #37
hollowboy is offline hollowboy  Australia
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Bracing: if you can reduce symmetry easily, do it. It is a small benefit that costs nothing ...but not a big deal if you don't wanna bother.

Stuffing: ditto. If you cross to the top box at 200Hz, the stuffing won't do much at all, hence an old pillow will be approximately as (in)effective as anything else.

Some people leave it out entirely, because no stuffing = a slight boost to port output / bass efficiency.
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Old 25th July 2018, 02:27 AM   #38
WillHoog is offline WillHoog  United States
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Amazon.com: Precision Port 4 Inch Flared Port Tube Kit: Home Audio & Theater

Something like that seems like a good option, I would just not use the other flared end since I have 1 flared end in UniBox. It would be short by 0.33071 inches in diameter, does that mean I should make the port length longer?

Also is the port length from the start of the flared end to the other end or should I measure from where the tube itself starts?
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Old 17th August 2018, 03:54 PM   #39
WillHoog is offline WillHoog  United States
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I still have more questions, why is no one responding?
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Old 17th August 2018, 09:54 PM   #40
kylemart is offline kylemart  United States
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There are few subwoofers you can get in cheap price which works perfect. Regarding the reviews, your car model, power and lot more technical terms
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