Sub/amp separation?

[joshua43214]

So I started pulling interior parts out of my car so I could plan the installation of the stereo that formerly lived in my Saab.

After looking it over and talking to the Kicker tech people, I have decided to build a sub enclosure that will fit behind the backseat. The enclosure will span the entire back of the seat and be just as deep as needed to give the sub 1" clearance, then internaly blocked up to give the desired volume.

Mounting the amp is the next issue, the thing is rather large, 21"x12"x3" and weighs a fair amount. I can either mount it directly to the bottom of the parcel shelf upside down, or I can mount it to the back of the sub enclosure.

Inverted mounting gives me better access to the amps controls and wiring, but this stuff is not touched once the system is running properly so maybe not such a big deal. I just like the idea of the sub, amp and EQ all being in one nice clean assembly. Not to mention better heat disipation if its not inverted.

I like the idea of it mounting to the enclosure since I would not lose any vertical space that way, but it would put the bottom of the amp less than 2" from the magnet on the 10" sub. Is there a problem with an amp being so close to a large magnet like this? and is there any thing I can do to sheild it if so?

[Rustam]

So I started pulling interior parts out of my car so I could plan the installation of the stereo that formerly lived in my Saab.

After looking it over and talking to the Kicker tech people, I have decided to build a sub enclosure that will fit behind the backseat. The enclosure will span the entire back of the seat and be just as deep as needed to give the sub 1" clearance, then internaly blocked up to give the desired volume.

Mounting the amp is the next issue, the thing is rather large, 21"x12"x3" and weighs a fair amount. I can either mount it directly to the bottom of the parcel shelf upside down, or I can mount it to the back of the sub enclosure.

Inverted mounting gives me better access to the amps controls and wiring, but this stuff is not touched once the system is running properly so maybe not such a big deal. I just like the idea of the sub, amp and EQ all being in one nice clean assembly. Not to mention better heat disipation if its not inverted.

I like the idea of it mounting to the enclosure since I would not lose any vertical space that way, but it would put the bottom of the amp less than 2" from the magnet on the 10" sub. Is there a problem with an amp being so close to a large magnet like this? and is there any thing I can do to sheild it if so?

I don't think you will be able to shield the magnetic field. I would move the amplifier away.

And, then if I understand you correctly you want to mount the amplifier to the subwoofer enclosure - the enclosure may be subject to some vibration, depending on design. So I would possibly stay away from mounting anything to it.

[Rustam]

So I started pulling interior parts out of my car so I could plan the installation of the stereo that formerly lived in my Saab.

After looking it over and talking to the Kicker tech people, I have decided to build a sub enclosure that will fit behind the backseat. The enclosure will span the entire back of the seat and be just as deep as needed to give the sub 1" clearance, then internaly blocked up to give the desired volume.

Mounting the amp is the next issue, the thing is rather large, 21"x12"x3" and weighs a fair amount. I can either mount it directly to the bottom of the parcel shelf upside down, or I can mount it to the back of the sub enclosure.

Inverted mounting gives me better access to the amps controls and wiring, but this stuff is not touched once the system is running properly so maybe not such a big deal. I just like the idea of the sub, amp and EQ all being in one nice clean assembly. Not to mention better heat disipation if its not inverted.

I like the idea of it mounting to the enclosure since I would not lose any vertical space that way, but it would put the bottom of the amp less than 2" from the magnet on the 10" sub. Is there a problem with an amp being so close to a large magnet like this? and is there any thing I can do to sheild it if so?

Why not mount the amplifier in place of the original amp? Is it too large?

[stargazer_61]

Build something to mount it in the trunk either under the parcel tray or better yet behind the back seat panel or by the well where the old one is. The amp needs room to breathe and for heat dissipation. Like Rustam said, keep it away from the magnetic field on the sub. Isolate all of your hardware with rubber so that you don't get the rattles. Easier to show off a custom installation job, too!

[pingu]

The amplifier will internally use negative feedback to ensure that it's output signal is a faithful reproduction of the input signal.

Although there are some theoretical reasons for keeping an amplifier away from the magnet of the sub, in the real world these reasons won't be an issue. It's worth remembering that the distortion of a loudspeaker (at normal listening sound levels) is roughly about a thousand times greater than the distortion of the amplifier. No matter how much you spend on loudspeakers, the loudspeakers will be the weak link in the chain - they distort far more than any reasonable amplifier. It is, however, important to make sure that the volume of the sub enclosure is suited to the parameters (known as Thiele-Small parameters) of the subwoofer.

[Rustam]

The amplifier will internally use negative feedback to ensure that it's output signal is a faithful reproduction of the input signal.

Although there are some theoretical reasons for keeping an amplifier away from the magnet of the sub, in the real world these reasons won't be an issue. It's worth remembering that the distortion of a loudspeaker (at normal listening sound levels) is roughly about a thousand times greater than the distortion of the amplifier. No matter how much you spend on loudspeakers, the loudspeakers will be the weak link in the chain - they distort far more than any reasonable amplifier. It is, however, important to make sure that the volume of the sub enclosure is suited to the parameters (known as Thiele-Small parameters) of the subwoofer.

You don't think that the amplifier potentially can have problems with Hall Effect being in magnetic field?

[genphreak]

Sounds like a good plan, a sealed enclosure from my experience sounds best. Keeps weight more forward too.

I put my amp under the shelf. It's kinda long but it fits fine. Lost 56mm of storage height but it is easy to do and keeps the connections near to the trunk's wiring loom. Use good self-tapping screws with both a flat and a spring washer to avoid it coming loose.

If you mount to your woofer enclosure the screws will vibrate out faster than anywhere else so you have to cover this more carefully. The problem with magnetism on your amp may be real or immaterial; however if it vibrates with the woofer the PCB ideally needs to be mounted on damped supports (which it won't be) and regardless the transistors bolt to the heat sinks so you will see fasteners loose in the amp after a while or even worse dry joints cracking earlier than they normally would (so try not to do it).

Nick

[joshua43214]

Thanks for the feedback every one.

There are 3 large lugs under the parcel shelf that I can bolt an amp mounting board to, I presume they are for mouning the rear power shade. They should easily support the weight of the amp. As for the sub, The enclosure will rest on the floor of the trunk and I will bolt it through from the other side.

Once I start actualy cutting parts, I'll post some pics.

[genphreak]

There are 3 large lugs under the parcel shelf that I can bolt an amp mounting board to, I presume they are for mouning the rear power shade. They should easily support the weight of the amp. As for the sub, The enclosure will rest on the floor of the trunk and I will bolt it through from the other side. Once I start actualy cutting parts, I'll post some pics.

Do you have the new style amp? Let us know when you post how you are wiring everything- if only we had a away to use the old crossover in the later model booster amps, the sound would be guaranteed. I am still marvelling over mine, it is tight and perfectly balanced, like BMW did it all perfectly in the first place for a high power setup but forgot to any hardware to reproduce signals below 100Hz and install the correct amps... of course I'll probably blow a tweeter or two soon, but the highs are not distorted or dirty in any way, even at full blast.

[joshua43214]

I doubt I would bother to upgrade the OE system in my car. It plays music nice and clearly, but any upgrade would just be maintaining the same poor imaging the system came with. I have lived with it for 2 1/2 years since it does the job reasonably well and its a pain to install the new system. I just can't stand being able to pick out each individual driver in the system with out even listening closely.

The only parts of the OE system I will be using is the power to the head unit and the antenna, the rest will be a clean install.