Upgrade options for the spare tire subwoofer module

[sthulin]

I was able to get full T/S parameters and modelled it in the Audi spare tire subwoofer enclosure simulation that I made a while back. Here it is against the Ampire Bold and the Skar EVL65. I dropped the other models for clarity since none of them offer anything worth all the trouble of mounting them. Judging by this simulation, it's likely the kicker sub will be very boomy in the car. But if that's your thing, it could still be useful for you. I'm not here to judge (plenty of others will). Kicker suggests only using it in a sealed box or with their passive radiator.

I just wanted to say you've done some great work here and really presented a few options for the community. Can you talk about the install process a little bit? Inside the enclosure, is it clips that need to be cut off to get bare wires? It also looks like you had to put a ring of foam around the edge to seal things off?

[JohnEnglish]

I know 0 about car audio. I'm thinking about upgrading my speakers but I want to keep the stock look. From your comments, it seems like the Skar is the best bet?

[zac3707]

I'm not going to do any further work with the Ampire bold 6.5 subwoofer driver, so if anybody wants it, let me know and PM your shipping address. I also posted it on audiworld so I guess I'll give it to whomever asks first by time stamp.

Hey bobby sent you a PM!

[Bobby Kinstle]

I know 0 about car audio. I'm thinking about upgrading my speakers but I want to keep the stock look. From your comments, it seems like the Skar is the best bet?

I think the skar is the best sounding of all the woofers that I've tested so far. but it's not completely a drop in you will need to modify the enclosure a little bit and use a thick foam tape around the edge to fill the gap. I would also add significant amount of polyfill stuffing to the enclosure.

It seems the kicker woofer that people are using is a pretty easy fit with minor modifications as well. I'm a little concerned by the simulation data that this woofer may be boomy but it will probably be much louder than the skar. he might be able to mitigate this by adding a lot of stuffing to the enclosure as well. The rep at kicker I spoke to says that this woofer really wasn't intended for this application so your mileage may vary. I don't have one of these woofers available to test but if you do buy one you should buy the dual voice coil four-ohm version that probably isn't available yet.

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[JohnEnglish]

A few follow up questions:

- I've read some people saying that the inside of the spare tire sub woofer enclosure should be sprayed with a few coats of bed liner. Do you think this would help?
- I've read a bit about removing some test tones via VCDS. Is this necessary when replacing the subwoofer?
- Is there any benefit to adding a separate subwoofer amp or upgrading the stock amp if you're keeping the subwoofer in the existing location?

[Bobby Kinstle]

A few follow up questions:

- I've read some people saying that the inside of the spare tire sub woofer enclosure should be sprayed with a few coats of bed liner. Do you think this would help?
- I've read a bit about removing some test tones via VCDS. Is this necessary when replacing the subwoofer?
- Is there any benefit to adding a separate subwoofer amp or upgrading the stock amp if you're keeping the subwoofer in the existing location?

Hi John,

I suppose you could spray some bed liner into the subwoofer box but packing it with polyfill is a lot easier. Deadening the chassis only helps with cabinet vibrations which probably isn't an issue for the subwoofer buried under the spare tire. Packing it with foam or polyfill reduces the internal echo which can have an effect on the tightness of the bass.

Turning off the test tones only matters if you are trying to power and amplifier and the amplifier or line output converter you're using does not have enough load on the factory sub output to pass the open circuit test. If you use a resistive load below 50 ohms you don't need to worry about this.

I'm not sure I would go through the trouble of adding an amplifier to power the spare tire subwoofer. I did add an amplifier to my car to run the rear deck subwoofer but that was mainly because I wanted to change the crossover point and not because I needed more power. There are other factors in play here and why you can get a more powerful subwoofer like the skar for example if a subwoofer extends too much it may rub on the battery. Port chuffing is also a big deal at higher volumes on this enclosure and there really isn't much you can do about that. I'm currently working with mine to remove the port and install a flared precision port and that is turning out to be a heck of a lot more work than I imagined it would be. I'm going to follow through with it because I'm already past the point of no return but I don't recommend this path for anyone. I think you would be much better off installing an underseat subwoofer under the passenger or driver seat or one of those side cubby subwoofer enclosures from basser.pl

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[JohnEnglish]

Hmm OK, thanks for the response.

[JohnEnglish]

How did you wire up the Skar sub? Like what color wires to what connectors?

[Bobby Kinstle]

No I'm only using test leads since I have an S4

[JohnEnglish]

Ah gotcha OK.

[Bobby Kinstle]

I started working on installing a flared port into the subwoofer box and this is WAY more work than I imagined it would be. This bad boy is going to be a one off that's for sure. I still have some large voids to fill but should be able to test it in the next few days. This should help with the chuffing a lot and lower the bass floor a little bit.

[zac3707]

I just finished installing the same Kicker sub (4ohm dual coil) as ssanderson with no luck. I am not getting any power to the sub at all. The other speakers work so its not the fuse (checked the amplifier fuse and it is intact). Wires are correctly installed to positive and negative terminals but absolutely no power going to sub. Anyone have any ideas what could be going on?

[sthulin]

I just finished installing the same Kicker sub (4ohm dual coil) as ssanderson with no luck. I am not getting any power to the sub at all. The other speakers work so its not the fuse (checked the amplifier fuse and it is intact). Wires are correctly installed to positive and negative terminals but absolutely no power going to sub. Anyone have any ideas what could be going on?

So the 4Ohm was supposed to overload the sub amp, but only if you turn the volume up. You should still get something if volume is down. Did you try and put the old one back in and see if it works?

[JD S4]

I just finished installing the same Kicker sub (4ohm dual coil) as ssanderson with no luck. I am not getting any power to the sub at all. The other speakers work so its not the fuse (checked the amplifier fuse and it is intact). Wires are correctly installed to positive and negative terminals but absolutely no power going to sub. Anyone have any ideas what could be going on?

You have your sub wired incorrectly somewhere


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[zac3707]

I figured out that the colored wires that Audi uses to connect the OEM sub have no rhyme or reason to them. There is no consistently with which wires are positive and which are negative. I basically had to try all the combinations and go by feel and ear to decide how to hook up the wires. I'm not sure how I would conclude for sure which colors are positive and which are negative.

[zac3707]

So the 4Ohm was supposed to overload the sub amp, but only if you turn the volume up. You should still get something if volume is down. Did you try and put the old one back in and see if it works?

I think the 2ohm would overload the amp from what I read in this post. The 4ohm has a dual coil over and can connect directly in pretty much the same fashion as the OEM

[sthulin]

I think the 2ohm would overload the amp from what I read in this post. The 4ohm has a dual coil over and can connect directly in pretty much the same fashion as the OEM

You're right, i mistyped. AFAIK the 4Ohm hasn't started shipping yet.

[zac3707]

You're right, i mistyped. AFAIK the 4Ohm hasn't started shipping yet.

I bought the same 4ohm as ssanderson and found it on eBay. So far no issues other then figuring out polarity


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[Bobby Kinstle]

I just finished installing the same Kicker sub (4ohm dual coil) as ssanderson with no luck. I am not getting any power to the sub at all. The other speakers work so its not the fuse (checked the amplifier fuse and it is intact). Wires are correctly installed to positive and negative terminals but absolutely no power going to sub. Anyone have any ideas what could be going on?

If you have one coil wired opposite from the other, they will cancel each other out and the sub won't move. This will burn out the sub VERY quickly so maybe get a DC resistance on both coils before proceeding

[zac3707]

If you have one coil wired opposite from the other, they will cancel each other out and the sub won't move. This will burn out the sub VERY quickly so maybe get a DC resistance on both coils before proceeding

Can you explain how I would get DC resistance on them? Right now the sub is moving and working the way it’s wired


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[Bobby Kinstle]

Can you explain how I would get DC resistance on them? Right now the sub is moving and working the way it’s wired

If it's moving then that's not your problem (or you burned out one of the 2 coils)

https://www.wikihow.com/Use-an-Ohmmeter

[Bobby Kinstle]

I just wanted to say you've done some great work here and really presented a few options for the community. Can you talk about the install process a little bit? Inside the enclosure, is it clips that need to be cut off to get bare wires? It also looks like you had to put a ring of foam around the edge to seal things off?

Sorry I missed your question earlier. For the most part the upgrade is pretty straightforward. The factory woofer screws into the enclosure with four torx screws and then it just falls out. Depending on which woofer you need to install, you may need to dremel out some of the structural webbing inside the enclosure under the magnet. The Ampire Bold pretty much drops in, but it's not a great match for this box and the upgrade will be minimal. The Skar requires some pretty significant box modifications including enlarging the opening slightly, removing all the structural ribs behind it, and even then you'll have a gap on the top side you'll need to fill with thick foam tape. Mortys66 told me you can heat up the plastic on the back with a heat gun a little and deform the box outward with the woofer magnet to get more clearance. Wiring is simple, just connect the new woofer the same as the old woofer. If you are B&O you'll want a woofer with two 4ohm coils, and if you are on the standard system you'll want the same thing, or a single voice coil 2 ohm woofer.

Always put some poly fill inside the box. That helps a lot.

The port modifications I'm doing now are a TON of work and I don't recommend anyone undertake them lightly. I'm just doing that to see how good I can make it. So far I'm still on my original assertion that an under seat powered sub is going to be a better solution for just about everyone that wants to keep the stock look.

[zac3707]

If it's moving then that's not your problem (or you burned out one of the 2 coils)

https://www.wikihow.com/Use-an-Ohmmeter

When using the ohmmeter, what would indicate which is positive and which is negative?

[Bobby Kinstle]

An ohm meter will not indicate polarity. but it will tell you if one of the coils is open circuit or burned out or shorted internally. A four-ohm driver typically reads 3.2 to 3.6 ohms and a 2-ohm driver usually reads around 1.8 ohms.

If you take a AA battery and connect it across the terminals of the woofer and it moves forward then the plus or the battery is connected to the plus of woofer. if it moves backwards then the battery plus is connected to the negative terminal in the woofer.

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[sthulin]

Looks like the 4Ohm kicker is starting to ship. I ordered one from crutchfield today and should be here this weekend.

[Bobby Kinstle]

I was looking at the box this morning and wondering why they made the back side arched toward the battery. It doesn't need to be that shape to clear the spare tire and it would have benefitted from having a larger volume enclosure.

[zac3707]

An ohm meter will not indicate polarity. but it will tell you if one of the coils is open circuit or burned out or shorted internally. A four-ohm driver typically reads 3.2 to 3.6 ohms and a 2-ohm driver usually reads around 1.8 ohms.

If you take a AA battery and connect it across the terminals of the woofer and it moves forward then the plus or the battery is connected to the plus of woofer. if it moves backwards then the battery plus is connected to the negative terminal in the woofer.

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But I want to know the polarity of the wires, not the polarity of the speaker. Is there a way to do that?


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[Bobby Kinstle]

But I want to know the polarity of the wires, not the polarity of the speaker. Is there a way to do that?


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You can test the polarity of the original speaker to figure out the polarity of the original wiring harness.

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[delfred91]

Looks like the 4Ohm kicker is starting to ship. I ordered one from crutchfield today and should be here this weekend.

Nice! I’ve been waiting for this to slightly upgrade the terrible B&O sub.

Can you leave a part number please?


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[sthulin]

Nice! I’ve been waiting for this to slightly upgrade the terrible B&O sub.

Can you leave a part number please?


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Kicker 48CWRT674

[JD S4]

Is this "the one" ??? I want to get the right one - not the fast one.

https://www.amazon.com/KICKER-CompRT...7381503&sr=8-2

[zac3707]

Is this "the one" ??? I want to get the right one - not the fast one.

https://www.amazon.com/KICKER-CompRT...7381503&sr=8-2

Yes thats the one. I will be selling mine in about a month. I just dropped it in so its brand new, but I realized I am going to go with a new 10" sub with enclosure altogether instead of this

[Bobby Kinstle]

Yes the 4 ohm dvc is the one you want

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[sthulin]

So who in this thread made this video?

[JD S4]

That was awesome tutorial. Thanks Jeremy

So. Who’s got this and who’s happy with it?


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[JohnEnglish]

He’s using the 2 Ohm version I think.

[Bobby Kinstle]

I would really like to know how the kicker woofer compares to the skar woofer but I'm a little past the point of no return on modifying my enclosure heavily for the skar woofer.

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[sthulin]

So i put in the kicker 4Ohm sub over the weekend. Not a huge difference in loudness, but it filled in more range for sure and it allowed me to turn the gain up without it sounding horrible. That ring is a pain to get off because it's glued on solid.

IMG_2251.jpg

[Bobby Kinstle]

So i put in the kicker 4Ohm sub over the weekend. Not a huge difference in loudness, but it filled in more range for sure and it allowed me to turn the gain up without it sounding horrible. That ring is a pain to get off because it's glued on solid.

Did you notice any PFBFBFBFBFTBFTFL sounds from the port (aka chuffing) when playing deep bass?

[sthulin]

Did you notice any PFBFBFBFBFTBFTFL sounds from the port (aka chuffing) when playing deep bass?

Not really? but i'm not sure i know what i'm listening for per say. Its still not producing deep bass tones, but i think thats the box design and factory amp. I did stuff the box full of pollyfill to try and help.