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Check my box specs please, won't play lows well. Frankenstein box question


Cbillings1985

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Hey guys,

I have a sundown SA10 V2 D4 running on a pioneer GMD9705, sub channel is 2ohm 600w.  I have a 2017 Chevy spark LS and I'm using the factory deck and an audio control LC7I.  I built my own box to fit behind the seat in the hatch.  Based on the calculator I used I should be tuned at 33.25hz.  Here are the box specs:

 

OD measurements

Depth 12.5" double 3/4" birch baffle

Width top/1 11"

Width bottom/2 19"

Height 21.25"

Port is 9" by 1.75" by 31" long with 2 bends.

 

ID measurements

Depth 10.375"

Width top/1 9.875"

Width bottom/2 17.125"

Height 19.75"

Port is 9" by 1.75" by 31" long with 2 bends.

 

Problem I'm having is I have gone through the audio control settings and set each of the 3 gains until they blink then back it off a bit.  I have tried various settings on bass restoration and level and when playing sign waves my highest peak is 50hz or so and I can feel the sub moving all the way up to 120hz.  Factory equalizer on the stock deck is set completely flat to allow the LC7i to do the restoration work.  Also a picture attached of my amp settings.  I guess what I'm wanting to check is my box built and tuned correctly to be actually tuned at 33.25hz or did I mess something up in my calculations causing the higher frequency output?  

 

Thanks for any help or suggestions. Gonna drive with these settings today to see what it sounds like.  I just know this sub is capable of way more output than I am getting and am trying to find out where my problem lies.

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So I have been reading on my amp specs in the owner's manual. Looks like it has a built in bass boost frequency of 50hz when using the bass knob. I haven't even hooked that up yet but why would they build an amp with a boost at 50hz? The 30s-40s are what I'd assume people want boosted most.  I'm going to hook up the bass knob today and see if it's any better.

 

Any help on checking to make sure I built my box correctly?

IMG_20200116_115458.jpg

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From the knob perspective, it seems its not a gain remote knob its a Bass Boost knob, so instead of building it into the amp like all other amps they built a knob for it, all BB is centered around 50hz pretty much. Interesting but deceiving move. 

 

As for the output, unfortunately IDK enough about boxes to know and have only watched videos from 5* Car Audio on YT using the LC7i, they have good in-depth tutorials

2015 Mazda 6

JVF Customz 4.0 Proto 15>Wolfram W4500 @ .5ohm

2 Sundown Neo 6.5 + 2 CT Meso Tweeters (Front) x Kicker KS6.5 (Rear)>JL Audio VX400/4i

NSB-AMG35 (front) / 40ah Lithium Headway (Rear) built by Erni Audio & Electrical

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your port tuning frequency is when your woofer is moving the least. if it looks like it is moving a lot at 50hz, stops moving 33hz, and starts moving again at 20hz, then you have your port tuned correctly. The bass boost at 50hz typically extends from 25hz up to 100hz. any bass boosting below 25hz causes more excursion than sound, and can blow subs up. that's why car amps don't typically have lower EQ adjustment.

 

Unfortunately that box seems fairly small for how large the port is - granted I haven't ran any of the numbers in my speaker software. the numbers hit me as the port is taking up most of the box space. A ported box is typically 2-3x the size of a sealed box, and then some for the added port.

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the Audiocontrol LC7i is just a signal summing line output converter. it has no sound processing power outside of Accubass which is solely for bass roll off from an OEM deck. I'd move from the LC7i to an LCQ-1 or DQ-61 or DM608. based on what you have I'd shrink that box down to 1 cubic foot net volume and tune to 30hz.

if nothing changes, nothing changes

You don't know what you don't know, till you don't know

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According to Tores (the program I use) your box is about .8 cubic foot. Sundown recommends 1-1.25 for a ported box, so it's a little on the small side.  Also you have too much port area in my opinion.  My program says your tuning is around 38-39hz.  All that being said, you should still be getting pretty good output with that setup.

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39 minutes ago, dwpjr said:

According to Tores (the program I use) your box is about .8 cubic foot. Sundown recommends 1-1.25 for a ported box, so it's a little on the small side.  Also you have too much port area in my opinion.  My program says your tuning is around 38-39hz.  All that being said, you should still be getting pretty good output with that setup.

Thanks for the comment. When I spoke to down4sound they said the port area was a good size so I went with it I'm at 15.75sq inches.  For the V1 SA sundown reccomends 16sq inches.  Slapbox specs are at 18sq inches  Do you know if the calculator I used is typically accurate?

 

Based on the amp do you think it's capable of playing the 30s well and not lower volume?  It's just not hitting the lows as expected. Did you use the internal dims I posted for your calculations?  I attached a picture before adding the double baffle

IMG_20191227_175848.jpg

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4 hours ago, mothra said:

the Audiocontrol LC7i is just a signal summing line output converter. it has no sound processing power outside of Accubass which is solely for bass roll off from an OEM deck. I'd move from the LC7i to an LCQ-1 or DQ-61 or DM608. based on what you have I'd shrink that box down to 1 cubic foot net volume and tune to 30hz.

I'll take a look at those processors from audio control. I may have to build a new box just don't want to take my entire hatch since the hatch is already incredibly small

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15 hours ago, jamboi9000 said:

your port tuning frequency is when your woofer is moving the least. if it looks like it is moving a lot at 50hz, stops moving 33hz, and starts moving again at 20hz, then you have your port tuned correctly. The bass boost at 50hz typically extends from 25hz up to 100hz. any bass boosting below 25hz causes more excursion than sound, and can blow subs up. that's why car amps don't typically have lower EQ adjustment.

 

Unfortunately that box seems fairly small for how large the port is - granted I haven't ran any of the numbers in my speaker software. the numbers hit me as the port is taking up most of the box space. A ported box is typically 2-3x the size of a sealed box, and then some for the added port.

I was hoping the box is not too small but I don't have any software for box calculations so I used the one I found online. I posted a picture before the baffle was added to see the port inside.  This is my first box I have ever built so I'm not ruling out the possibility I made a mistake 😁.  I do have enough wood left to build another box if needed.  Is the shape going to affect my output at all? I made it that shape to take up all available space behind the seat with the smallest footprint. 

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On 1/16/2020 at 9:19 PM, jamboi9000 said:

your port tuning frequency is when your woofer is moving the least. if it looks like it is moving a lot at 50hz, stops moving 33hz, and starts moving again at 20hz, then you have your port tuned correctly. The bass boost at 50hz typically extends from 25hz up to 100hz. any bass boosting below 25hz causes more excursion than sound, and can blow subs up. that's why car amps don't typically have lower EQ adjustment.

 

Unfortunately that box seems fairly small for how large the port is - granted I haven't ran any of the numbers in my speaker software. the numbers hit me as the port is taking up most of the box space. A ported box is typically 2-3x the size of a sealed box, and then some for the added port.

So I was able to turn the volume up today for a bit and ran through a frequency sweep 1hz at a time using an app called "frequency sound generator". I moved 1hz at a time and had the most air movement at 32-38hz and was much less air than I expected.  Least cone movement at 31-32 then the cone movement got faster and started to move more/longer excursion until the 50s then tapered off. I could feel the sub moving up to around the 130s which I find suspicious since I have my LPF at 60hz and switch on 24db at cut.  

 

I am a little ignorant to systems since I haven't had one since 2004 and it was an Orion h2 15 in a sealed box, I feel that produced the low bass significantly better than what I'm finding right now.

I'm getting good output it's just at a higher frequency than I'd prefer. It sounds peaky to me. Waiting to have a co-worker get his system back in.  He has an older model sundown X12 and it's very impressive on only 400 watts from a bridged 4ch fosgate amp.  That should give me an idea if it's my amp or factory deck not producing the lows well and needing an equalizer or if it's my box

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