Jump to content
SAU Community

Recommended Posts

I have a single 12" sub in my R33 and I face it towards the end of the car.... Sounds good! I've had a sub pointed into the car in my R31 when i could fold the seats down and almost sit it inside the cabin, but there's not as much bass as being faced the other way and as an enclosed unit (boot)

Just looking at my R32 it seems logical to mount a sub in a sealed box through the plate behind the back seat.(see my posts #18 &

#22 " Where's the bass? " this forum). I've run this idea past a few installers and most have recommended something else for one reason or another. One guy quoted a couple of articles on bass loading in CSA magazine. I found these articles (issues #5 & #9) and I must say that in these tests the forward facing mounting position had the lowest SPL and very uneven frequency response. The main difference between my idea and their setup is that my cabin will be sealed from the boot and their's fires through an open ski-port.

Gester,

The answer to your question is "none of the above"

Try standing in the middle of a room (of any given size) and speak at a normal level. Now go to a corner, face the wall and repeat...

This is why manufacturers of Hi-Fi speakers ALWAYS recommend positioning at least 40-50cm from a side wall - The bass response would lift considerably and "muddy" the soundstage. In a car where you WANT lift face the driver toward the rearmost corner in your boot. You won't win any fashion contests doing this, but you will optimize bass response using the natural acoustics of your car.

Let me know if it makes a difference !

  • 2 weeks later...

wow... almost looks like there is some boot space left there with that setup! :P

My 12" sub should be ariving any day now.. Will be interesting to see what i can do as well. I don't want to lose too much boot, but i know that i will in one way or another.

With bass, low frequencies are a lot more omni directional than higher frequencies, therefore staging is not as important in general in a sub. If you think about it, higher frequencies have less area and therefore bounce around more and are affected more by where it is positioned - so its important to get that part right.

That is why most home theatre applications they generally say you can position the sub most of time where it fits when there is all these theories of where you should be positioning all your other speakers.

I think where you position the sub is not as important as the enclosure (where it develops most of its sound) and the mounting itself (not loose). The key is to make sure there is no non-harmonic vibration or "buzzing" developed. I wonder whether adding sound insulation into the wells and other "open" spaces in there is going to help aswell so less sound can escape?

There is probably a massive art to getting it all perfectly right and requires many complex tools that us peeps probably don't have access to. I'd say unless you do something really stupid its going to sound pretty good - and bass in the end is only part of the equation (for me anyway!)

btw: I don't think that side setup would be that optimal, as really there is really little room for proper resonation behind the speaker, other than the side wells (which are pretty small really and not that effectively shaped)... however you would have good resonation from the front of the speaker, as there is no box filling the rest of the boot. I still think the former is more important though.

I'd say while more practical, you would be sacrificing some volume and quality there.

Originally posted by predator666

With bass, low frequencies are a lot more omni directional than higher frequencies, therefore staging is not as important in general in a sub. If you think about it, higher frequencies have less area and therefore bounce around more and are affected more by where it is positioned - so its important to get that part right.  

That is why most home theatre applications they generally say you can position the sub most of time where it fits when there is all these theories of where you should be positioning all your other speakers.  

you are partly right predator.

in terms of a room, with a large air volume and semi-infinite space, the location of a sub is not "as essential". However, within a car, the primary governance in terms of the effectiveness of bass drivers is the relationship between active and passive wave cancellation.

wavelengths for bass travel are typically in the order of 3m. as governed by c=f x lambda (assuming c=3.3, and f=80 Hz mean). for the best amplitude response, the listener should be positioned at the anti-node of the source. in terms of a woofer driver, this amounts to a multiple of the wavelength.

In short, the MOST CONSISTENT way of acheiving this is to direct the driver toards the back f the trunk. this allows reflecion of the sound wave off rear boot surface (approximately 0.5m) and then travel from the boot to the front of the vehicle cabin (about 2.5m, depending on the car).

this method typically produces best resullts for single driver setups in sedan sized vehicles in terms of SPL. some experimentation may be necessary to determine whether the sound is better when the driver is facced into the LH or RH corner or directly backwards.

  • 3 weeks later...

Gester I'm still undecided as to whether to put the sub behind the seat or in the wheelwell. I don't see it being too difficult to go behind the seat once you've relocated the battery though. I'm still toying with the idea of facing it foward through the arm rest hole but if I do this I can only fit one 10". If i face it backwards I can fit 2 x 12"s easily.

Has anyone managed to put the Sub in the compartment with the battery?

Yep, done it. Single 10" drivers side, facing into the boot, and currently working on the second once I have relocated the battery. 12"s would fit no problem, provided they arent going to be too deep. You can always bring the false wall forward to compensate though, just means less boot space (tis why I have 10") All I need to do now if buy decent 10"s rather than the Sony's I was given :):D

I got mine like the pic above with the driver facing the left suspension tower roughly. Its a solobaric L7 square so the box is absolutely small and the sound is mad for such a small driver in such a miniscule box. also get some brown bread deadener and deaden the boot lid and anywhere else you can fit some if there is any left exspecially the boot floor.

perfect

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Surely somebody has one in VIC. Have you asked at any shops?  Is this the yearly inspection or did you get a canary?
    • This is where I share pain with you, @Duncan. The move to change so many cooling system pieces to plastic is a killer! Plastic end tanks and a few plastic hose flanges on my car's fail after so little time.  Curious about the need for a bigger rad, is that just for long sessions in the summer or because the car generally needs more cooling?
    • So, that is it! It is a pretty expensive process with the ATF costing 50-100 per 5 litres, and a mechanic will probably charge plenty because they don't want to do it. Still, considering how dirty my fluid was at 120,000klm I think it would be worth doing more like every 80,000 to keep the trans happy, they are very expensive to replace. The job is not that hard if you have the specialist tools so you can save a bit of money and do it yourself!
    • OK, onto filling. So I don't really have any pics, but will describe the process as best I can. The USDM workshop manual also covers it from TM-285 onwards. First, make sure the drain plug (17mm) is snug. Not too tight yet because it is coming off again. Note it does have a copper washer that you could replace or anneal (heat up with a blow torch) to seal nicely. Remove the fill plug, which has an inhex (I think it was 6mm but didn't check). Then, screw in the fill fitting, making sure it has a suitable o-ring (mine came without but I think it is meant to be supplied). It is important that you only screw it in hand tight. I didn't get a good pic of it, but the fill plug leads to a tube about 70mm long inside the transmission. This sets the factory level for fluid in the trans (above the join line for the pan!) and will take about 3l to fill. You then need to connect your fluid pump to the fitting via a hose, and pump in whatever amount of fluid you removed (maybe 3 litres, in my case 7 litres). If you put in more than 3l, it will spill out when you remove the fitting, so do quickly and with a drain pan underneath. Once you have pumped in the required amount of clean ATF, you start the engine and run it for 3 minutes to let the fluid circulate. Don't run it longer and if possible check the fluid temp is under 40oC (Ecutek shows Auto Trans Fluid temp now, or you could use an infrared temp gun on the bottom of the pan). The manual stresses the bit about fluid temperature because it expands when hot an might result in an underfil. So from here, the factory manual says to do the "spill and fill" again, and I did. That is, put an oil pan under the drain plug and undo it with a 17mm spanner, then watch your expensive fluid fall back out again, you should get about 3 litres.  Then, put the drain plug back in, pump 3 litres back in through the fill plug with the fitting and pump, disconnect the fill fitting and replace the fill plug, start the car and run for another 3 minutes (making sure the temp is still under 40oC). The manual then asks for a 3rd "spill and fill" just like above. I also did that and so had put 13l in by now.  This time they want you to keep the engine running and run the transmission through R and D (I hope the wheels are still off the ground!) for a while, and allow the trans temp to get to 40oC, then engine off. Finally, back under the car and undo the fill plug to let the overfill drain out; it will stop running when fluid is at the top of the levelling tube. According to the factory, that is job done! Post that, I reconnected the fill fitting and pumped in an extra 0.5l. AMS says 1.5l overfill is safe, but I started with less to see how it goes, I will add another 1.0 litres later if I'm still not happy with the hot shifts.
    • OK, so regardless of whether you did Step 1 - Spill Step 2 - Trans pan removal Step 3 - TCM removal we are on to the clean and refill. First, have a good look at the oil pan. While you might see dirty oil and some carbony build up (I did), what you don't want to see is any metal particles on the magnets, or sparkles in the oil (thankfully not). Give it all a good clean, particularly the magnets, and put the new gasket on if you have one (or, just cross your fingers) Replacement of the Valve body (if you removed it) is the "reverse of assembly". Thread the electrical socket back up through the trans case, hold the valve body up and put in the bolts you removed, with the correct lengths in the correct locations Torque for the bolts in 8Nm only so I hope you have that torque wrench handy (it feels really loose). Plug the output speed sensor back in and clip the wiring into the 2 clips, replace the spring clip on the TCM socket and plug it back into the car loom. For the pan, the workshop manual states the following order: Again, the torque is 8Nm only.
×
×
  • Create New...