Video Building a Sub Box for BMW Z3

Antm72

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I will pull my box too just waiting to get the stitches out and it might be easier !! Will see what i can do :thumbsup:
 

littlefeller

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well - i knew there was some advantage to using a clear acrylic box, just hadn't figured why till just now. so it was snowing and I got itchy fingers and decided to just wire it up in the boot and try it out (cant strip the cubby as its snowing). first of all - forgot the remote wire (head unit doesn't have one) at first I thought duff amp:( then I figured why and jumped it from the live YEH now we are in business, sat listening to the bass for a couple of min, then twiddled with the knobs finding the sweet spot YEH that's it aahhhhhh. then after about 5 min I noticed the sub box wasn't so clear any more:confused: then after about another 30 seconds the whole box was full of smoke to the point where I could not see through it anymore:eek: never have I had to de-wire something so quickly=)). well that's that then, the driver for some reason decided to spontaneously combust even though the amp is max watts 250, so in reality more like 150watts, driver is supposed to be 300 watts and a peak of 600 ummmm don't think so.
so its back to the search for a driver=)) still it did sound good (briefly) looked good too as the box changed colour, if i had used mdf I would have been completely unaware, even worse if it had put it in the cubby:nailbiting:. lesson learned, don't skimp on the driver:mad:

next time less bass boost=))
 
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Antm72

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Its all working in theory then just the sub thats not up to the job ?
Back to the drawring board or better sub ?
 

littlefeller

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It may have been me, I took the driver apart last week to see how much I could actually strip off it, they have had some good reviews (wonder if Thomsons are seconds hence the price, the reason I think this is when I took it apart some of it - ie the coil was off centre) don't know, I'm tempted to try another one (never learn). failing that I have been having a good look around, there are quite a few sellers in Germany of replacement woofers might give one of these a try if I can find the right size and wattage.

I will dig out the massive woofer in the shed and hook it up to the amp to see if its ok, the amp hasn't been used for years, it is an old maystar qtx250
 

Antm72

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I thought that it was well made but never stuck power to it.
To smoke up it sounds like a short maybe there was a coil problem.
You could check the amp out but if it was to fail normally they protect (switch off) rather than over power anything.
 

littlefeller

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probably damaged the coil taking the back off it, so the search continues.
 

littlefeller

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ok, i have come to a conclusion why i smoked the sub, i tested the amp with a larger cone today (same impedance) but now the cone is larger it is really obvious why it started smoking, i am getting loads of distortion on the same gain setting as i was using on the smaller sub, so conclusion is - need a bigger amp (or lower wattage speaker).
 

Antm72

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Under driving should not cause it to smoke though i wouldn't have thought?
Technically i think the H.K system under powers the kicker i run but no issue i have found.
Hopefully you can resolve it without mega cost !
 

littlefeller

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i dont think it was the under driving that was causing the issue, more the big distortion. i have tried the 6.5 again (still works:)) and again i watched it as i turned up the gain, about half way up it starts to push the cone quite far out, to the point you can see it distorting, i think the signal isnt man enough (or rather it gets to the point where its just noise), maybe i should try again, this time turn the gain off and wind the head unit up to just before it starts distorting, then start on the gain, thinking maybe im trying to amplify a weak signal.
 

littlefeller

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THATS IT, that is exactly what mine was doing, even the smoke=)) but others have brought and rated these drivers, ok some say you get what you pay for while others say there great, depends on what you are used to i guess, yeh sure if you have a £3000 hifi at home then yes it probably doesn't sound that great, but in a car it should be fine especially in a convertible.
at first i thought oh heck - how the hell is it not going to crash into the cross member going like the clappers like that, but again im convinced it was distortion in the signal (my amp isnt powerful enough to do this unless the speaker is actually rated at about 50w (unlikely) i tried it in another amp (so called 350w -ha- a bit overoptimistic i think what with its 15 amp fuse i dont think so) it hardly even moved but the signal was fine.

you will notice in the vid that the driver is open, it is supposed to be in an enclosure, mine wasnt either, (took the back of the box) im now wondering if without the air dampening it can over reach.
 

Antm72

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I suppose you could get too much extention of the cone but have seen these in vented enclosures so unlikely.
I think it was either a fault or when looking at other youtube vids one state no more than 120w as his just clicked and was completly shot.
Like you say though some appear to think they are great.
Mines rated at 175 Rms Max but the H.K Amp is only at 30 watt Rms Peak so still think its an over driven thing especially if on the free air side.
 

littlefeller

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think your correct, just going through some of the reviews - here one -
These subs are superb if your gonna fit them in your car doors like me.
Dont over power them ive amped them using 90w rms per door and thats enough or your cook them.
They sound the dogs b......s no what i mean. pure bass just compliment them with some good tweeters,
AWESOME DUDE!

so yes it does appear the 300w recommended will just blow them straight away, ooops:). before i twiddled with the boost and gain it did sound really good,. umm think maybe another type is in order.
 

littlefeller

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i have those in my watch list, there are actually quite a few options, all have there pros and cons, i found a sight in Germany that specialize in high end woofers recovery from returned home hifi systems, im waiting for one to come up with a decent wattage. in the meantime something like these would be good, i have even considered 2 x 5.25 inch, both at 8ohlm but in parallel would be 4ohlm increasing my wattage potential.
only problem here is would they be bass-ie enough
 

Antm72

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The HK system runs 2x 5.25" speakers back to back but i've tried this route swapping the stock speakers for new units and rewiring etc but to no avail the sound is just poor.
The single speaker is the way to go @8 ohm though you would have to drive it twice as hard for the same power/ sound.
The H.K speakers are 2Ohm as stock and replacing them at 4Ohm meant in my case that certain speakers where powered right and some quieter ,you then end up with loud distorted speakers to get the right amount of sound out of your settup so it works but its defo not ideal for getting what you want.
It may be easier on your case as your headunit powers front and rears so you could get a balance with an amp i suppose.
 
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