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ncc74656

fi bl to sp4? and amps?

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I own a 18" BL fully loaded on a kicker ZX1500.1. this has done me well as a DD setup for a year but now i want more. I am looking for more low end and more volume with out sacrificing much of my high end. my box is currently tuned at 44hz @ 5.4 cubic feet and i was planing to build a new box tuned to 35hz @ 7.99 cubic feet. i have the option to swap my 1500.1 with a 2500.1 plus a couple hundred and stick that behind the BL. would i blow it with this setup assuming im not an idiot with gains and the bass blow knob?

 

my second thought was to sell my sub and box to buy a SP4 and stick that on a BC3500.1D crachendo amp. i read that this amp can run .5 stable where as my kicker prefers to sit 1.5-2ohm. my understanding of things is if i change my parallel/series wiring on my current dual 1ohm sub that it will run at .35ohm as each coil is .7. would i blow something up running a SP4 with a BC amp at such an ohm rating?

 

I am currently satisfied with the frequency response of my BL with the exception of low end, which i acknowledge is a box design issue rather than a sub spec issue. i am unsure what route to choose. will the SP4 match the BL in sq? will the kicker be to much or to little for the BL, will the BC melt at .35ohm, am i not understanding anything correctly?

 

The box i was planing to build is .75mdf with a coat of resin and rounded edges. i assume other than changing some bracing for mount depth that a BL and SP4 could run in the same box? this is what i was planing on building:

 

http://imgur.com/a/coFsq 

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That's why it's not picking up the low end, your tuned pretty high for daily. Build a new box like you said first. If your not satisfied then buy a new amp/sub. If you don't really have the knowledge and experience, I wouldn't suggest running an amp at .5 ohms.

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start with a lower tuned box. why would you run the bc3500 below 1ohm if the sp4 is a 3000w rms sub?

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start with a lower tuned box. why would you run the bc3500 below 1ohm if the sp4 is a 3000w rms sub?

 

The Sp4 can take that power and then some.

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build new box with lower tuning..... go from there

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It is not a dual .7 that is dcr it is closer to 1 ohm

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ok so the amp sees each sub coil as maybe .8-1ohm per coil. i use silver wire so the resistance is a bit lower there. suppose that explains why my kicker has not blown up running at 1.4ohm. because its really running more like 1.7-2.2 ohm depending on various things. i should ohm it all out one day and find out exactly what the amp is seeing...    i was thinking of using a BC3500 because i believe the SP4 fully loaded could handle the power. however from what im reading now the SP4 would be closer to .5 ohm anyway and thus would deliver 3200W+ to the sub. i think that sounds like a very good pairing, no?

 

another question in regards to the baffles of the box (and maybe ill make a new thread about box construction), if i have 2 sheets of MDF on the face and 2 holes cut, one for sub basket mounting and the other for the diameter of the sub so its recessed past the outside baffle. does that still count as a double baffle? or should both holes be even so the sub screws through both sheets?

 

finally does anyone have a good link for info on how to o-scope gains/bass boost levels on the deck/amps.

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It would still be a double baffle if you counter sink the subs.

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i posted a box build question in another forum. if anyone happens to know anything about boxes id appreciate any kind of validation on whether or not im an idiot. thanks.

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You can't "ohm it out to see what the amp is seeing".  You can measure the DCR with a DMM, but this will be lower than the box impedance 95% of the time and doesn't give you any real idea of the load your amplifier will be presented...

 

You need test equipment in addition to a DMM to measure impedance.

 

There is no such thing as impedance rise.

 

You are using pure silver speaker wire?  What gauge?  Last time I used solid silver it was Kimber Kable and was over $100 a foot...

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You should see Ray's motorcycle collection. Snake oil obviously is a good business biggrin.png

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its 4ga, its silver wire and came with my kicker amp. i do not know what purity it is but i know that silver has a hair lower resistance than copper does. on a side note... your damn banner ///M5!! i cant even figure out what im going to type, totally derails my train of thought >.<

 

 

if i upgrade my sub i wont be using that wire anyway because ill be going up to 0ga through out the amp setup and i suppose maybe 4 into the sub. idk how large the terminals are on a SP4. the main concern i have is if my box that i intend to build is setup right. in some of the fi videos they talk about a certain port area that is optimal and i cant find that info on the SP4's. i have mine setup with a 16.29 squared port area right now. my thought was that adding some poly fill will make the sub think its in a slightly larger box and off set that port area, or does it not work that way?

Edited by ncc74656

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Typically poly fill is used in sealed enclosures. There are many calculators to help you figure out how to tune your enclosure properly. I highly doubt you will get 4 gauge wire into any sub terminal.

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well i think i have tuned it all right but i just want someone who knows more than me to verify it so im positive before i start gluing stuff... maybe ill just extend the length by .5" to take the box up to 7.89 cubed and then the port area will be at like 15.8" squared.

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Ok, lol that isn't silver wire...

 

Polyfill is used to change the Qtc of a sealed enclosure (make the woofer behave as if it is in a bigger box), it doesn't do the same thing to vented enclosures.  You don't need to add any fill to a vented anclosure that only operates over the bottom 2 octaves.

 

Use one of the suggested FI alignments or have someone help you with your box design.

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i cant find a pre-build for a SP4. i finished my final design cut outs last night and i think its all good. i do have one final question however. my port bends and at the bottom of my port are 2 vertical braces. does this effect the port? if so what needs to be changed? here is a picture: 

 

Zxc2uIY.jpg

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what are we looking at here with this enclosure picture....

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hell i dont know anymore. that was an old enclosure design i had built up months ago with the help of the12volt.com and SMD forums. im so far from that design now tho... im looking at 7 cubed, 118 squared port area, 33hz tune, 31.5X3.75 slot port. i have a guy who is telling me to go octo port so i might have one more box redesign in my future.

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Ohh ok, I have an sp4..and my design is on the forum.. its a basic slot port.. I keep it simple, clean, and LOUD!

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yea ive stepped back on the redesign. i am considering an octo port tho, not sure how that would work out.

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by that definition it makes me think the SP4 will have more response than the BL i had. id be very surprised if that were the case considering the power difference. 

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