Symposer Defeat
 

If you're like me (don't feel bad if you're not: not many are) you don't like the sudden change when sound suddenly gets pumped into the cabin by the "symposer" system. I like to hear the engine sounds coming from the front and the exhaust sounds coming from the rear. The directionless noise that appears when I hit the right RPM and load is annoying to me.

Here's how to defeat it, and it takes only a few minutes and pennies worth of material.

Remove the engine top cover by pulling it straight upwards. There are four grommets that secure it.

Here's the fitting that connects the top of the symposer to the tube that pumps sound into the cabin. Remove the indicated bolt.

https://cimg9.ibsrv.net/gimg/www.jag...e21dd027f9.jpg

Wiggle that elbow as you pull upwards on it. It should come loose like this:

https://cimg6.ibsrv.net/gimg/www.jag...13cf9eec4c.jpg

At this point, I rolled up some ensolite insulation left over from a sound-deadening project a couple of cars back and blocked the passage. If you don't have that, perhaps a cork could be carved to fit: Maybe from some Tattinger or a nice claret.

https://cimg8.ibsrv.net/gimg/www.jag...cc4315e5fc.jpg

Reassemble and drive.

I'm probably going to try putting a ball valve into the hose, not because I think I'll ever want to re-enable it but so that I can from time to time as a reminder of why I don't like it.

Just popped the bonnet to take a look-see as I didn't believe that the convertible had this fitted...to my surprise, it does, however thankfully you can't hear it even with the hood up!

Here's the culprit...

https://cimg1.ibsrv.net/gimg/www.jag...0ceb4231c7.png

Lizzardo, some questions re: the symposer:

1. What do you mean when you say that it "pumps" sound into the "cabin"? How?

2. To what location (endpoint, outlet) in the cabin is the sound "pumped"?

3. What activates it (turns it on and off). RPM?

Thanks.

I'll refer to the diagram posted above by Tel:

The word "pump" was perhaps a poor choice. Channels sound? Directs sound? Piece #11 bolts to the intake manifold and is the source of the sound. The complex device at the bottom left (no number in the truncated diagram, but that's the "symposer") must condition the sound in some way, maybe muffling the mechanical sounds to give the desired quality.

Sound is channeled from the symposer through hose (#12) to the elbow shown in my photos (#1), through hose (#3) to #5, which bolts to the firewall. It is a small megaphone for the sound, which then resonates from behind the dash.

Parts #7 and 8 must be the switching mechanism. I don't think there is anything electrical, so it must be by manifold pressure/vacuum. It's been a while since I looked at all this carefully, but I don't recall any electrical connections.

I hope this helps. It really does take only a few minutes to try this out.

Here's a description of how the V8 Symposer works, no doubt the V6 would work in a similar if not identical way:

https://cimg0.ibsrv.net/gimg/www.jag...e980642201.jpg

Although it doesn't explain what the "targeted frequency range" or the "certain conditions" are.

Targeted frequency range is probably the same for both, in that they'd want to get rid of high-frequency mechanical noise and keep sounds in the same range as the exhaust. Certain conditions are easy enough to figure out. When I put my foot into it the car accelerates, and at a certain point the noise in the cabin jumps. The artificiality of that on/off behavior is possibly what annoys me the most.

Has anyone tried this method besides me?

I got a valve and some clamps to make mine switchable, but haven't been motivated to put it in because I've yet to convince myself that I ever want it back.

Thank you!!!

I'd rip it all off if it was easy to do.....


Dave

Save some weight :)

What do think that contraption adds to the cost of the car, including engineering? $1k?

One of the other boards here (XK?) has information about removing it, noting that it was anything but easy.

I don't think the weight is as significant as clutter. There's enough carp under the hood already.

I have no idea. I don't even understand how anyone thought it was a good idea.

"I know, let's add disembodied drone that switches on like a light switch!"
"Brilliant!"

I do still wonder if anyone else has tried my 5-minute symposer defeat. Anyone? I'm pretty sure you all know how I feel about that thing, and about the sound without it.

It's on my list, I'll try it within the week,

I want to do this, but I don't know what fire-safe material to stuff in there.

I used ensolite left over from a sound-deadening project. This is in a plastic elbow that has a complex plastic piece between it and the engine. If flames get to there, the symposer itself will already be on fire.

If you're still worried, some header-wrap material would surely be fire-safe. Something like this:

Thermo-Tec : Exhaust Insulating Wrap

I even have some, but didn't think about it for this use given the materials of the system upstream of the plug I added.

Exhaust wrap is a great idea, thanks!

It needs to block sound, not flow (it dead-ends at the firewall) so keep that in mind when making the plug.

I wonder if the XE V6 has this also? Where is this on the motor exactly, rear or front of engine?

On the rear, that's why it's a PITA to remove.
Dunno if the XE V6 has it though.