2016 Porsche Macan S - stealth SQ build

[Ge0]

So my other test subject came in :




Actually a pretty cool looking sub. The logo on the dust cap is slightly cheesy (wish it was matte black) but I can live with that. It will be hidden.

Ge0

[geolemon]

Look at that sexy surround. All it's missing is a Cerwin Vega stroker front spider and pole piece clamp!

Seriously though - flat panel subs don't usually have huge Xmax or anything. I wonder if they were simply avoiding a half-roll surround just so that you could squeeze that sub really tightly firing into the bottom of a seat or a wall or floor or something? Although I suppose an inverted half-roll could do that too...

[Ge0]

Look at that sexy surround. All it's missing is a Cerwin Vega stroker front spider and pole piece clamp!

Seriously though - flat panel subs don't usually have huge Xmax or anything. I wonder if they were simply avoiding a half-roll surround just so that you could squeeze that sub really tightly firing into the bottom of a seat or a wall or floor or something? Although I suppose an inverted half-roll could do that too...

There is a totally unofficial redneck review of this sub by SDA. You should see this freaking cone move through it's stroke under serious power. Holy be-jesus!!!

Others have talked me into trying this little beast. Let's see where she shines...

Ge0

[Ge0]

So here is an interesting experiment. I was attempting to evaluate the 10TW3-D4 using the Bose stock subwoofer amp:





The stock sub is 4 ohm. The 10TW3-D4 is 2 ohm. I would have thunk this would produce a higher output. I was wrong. The Bose amp pushed the sub. But not as hard as the stock front midbasses. I took these plots over and over again. They all came back the same. The midbasses out-power the sub! Either the stock sub amp sensed the low impedance load and backed off. Or the stock sub does not do schitt in contributing to total output.


Blue is with sub connected. Red is with sub disconnected and front midbass only. Hardly a difference if at all.

My next step will be to replace the Bose stock Sub amplifier and to replace with something more substantial. Hopefully more on this coming soon.

Ge0

[Ge0]

Deleting duplicate post

[phroenips]

When I measured my stock sub, I remember the nominal impedance being something like 1.6 ohms. You can easily test your theory of how much the stock sub contributes simply by taking measurements with it connected and disconnected.

[Ge0]

When I measured my stock sub, I remember the nominal impedance being something like 1.6 ohms. You can easily test your theory of how much the stock sub contributes simply by taking measurements with it connected and disconnected.

That is exactly what I am about to do. Put the Bose sub back to the original and re-test. That, and I'm going to strap a bigger amp onto Frankensub. It's hot as hades outside today. May need to bring some work back inside until night fall

Ge0

[Ge0]

So, you know your amps DSP software is old when:




Seriously. I had to wipe the old DSP settings from my last vehicle. I don't intend on using the DSP inside the DC 500.1 on my next install. That will be taken care of by a newer processor. This sucker will just be used as a straight amp with enough muscle to push one or two subs.

Per recommendation above, I am putting the Bose sub back together to take readings off it. Something doesn't seem right with my findings yesterday. I did install these quick disconnects though. I will be using the harness into this amp for line level audio (yellow and purple) plus a remote turn on feed (white) for now.



Oh, and I stand corrected about my earlier observation. This subs coil Re is 2.5ohm +/- 1ohm. Therefore its average impedance will probably be somewhere between 2 and 3 ohm. This is just like the measurements of the JL 10TW3-D4 I just tried out. I will try to do some testing tomorrow before it gets too darn hot to be outside.

Ge0

[Ge0]

OK. I did a lot of experimentation today with sub location in 90 degree heat with 80% humidity (it has been 45 degrees here lately). This was brutal. To level the playing field I kept the factory sub and adjusted position and conditions within the vehicle to measure affect. All measurements were made in the drivers position with the microphone midway between ear positions. The idea was top study vehicle dynamics, not just equipment. The only unknown is what funky filters the Bose Factory DSP placed on the signal prior to amplification. In my opinion, if they did EQ the sub they screwed up massively.

First off. No sub installed vs. with factory sub. Note, the Macan has 8" woofers mounted in the front doors with no high pass filter:


You can see that the factory sub does not add low end. But, it does make a few funky boosts. Most notably at 80Hz. Also notice the massive suck out at 60Hz.

Next, here is the factory sub with the rear cargo deck open. Notice the attenuation's at 80Hz and 100Hz that occur when the cargo lid is open. It's like a loading affect is minimized.











Now, move the factory sub from stock location to an up firing position under the cargo floor. This is similar to implementations by a number of people who have modified this vehicle. As it turns out, the frequency response is almost identical to the factory mounted location:







Strange things happen when you fold the seats down:




Frequency response amplitude boosts slightly but shifts up in frequency by about 5Hz.

More in the next post...

Ge0

[Ge0]

Now I will move the factory sub above the hidden cargo floor and aim it all over the place.


Similar to the sub firing up under the floor but now sitting on top as if mounted in a baffle to directly fire into the cabin:




Interesting, the peak at 80Hz is reduced significantly. However, there is a significant dip created at 100Hz.




Mimicking a floor mounted sub pointed backwards:


This orientation yields a slight boost at 80Hz over the up-firing orientation. Also, the dip at 100Hz still exists but is less pronounced:




Mimicking a right side firing subwoofer that would be mounted in the left side panel:



Results are very similar to the rear firing sub orientation. Slightly less boost at 80Hz and dip at 100Hz:




Mimicking a left side mounted sub firing right. Cable lengths prevented me from moving all the way over to the right:



Results are within 1dB of right firing sub orientation. This is within measurement to measurement error:



There are a few commonalities no matter how the sub is oriented:



1.) The sub adds no low frequency extension beyond what the front doors provide.
2.) Orienting the sub differently does not add any low frequency extension.
3.) No matter how the sub is oriented there is always a suck out at 60Hz.
4.) Boost at 80Hz and dip at 100Hz varies with sub orientation
5.) Installing the subwoofer under the cargo hatch floor adds bass boost. As a matter of fact mounting under the cargo floor eliminates the dip at 100Hz.
6.) Folding the rear seats down and opening up the hatch to the front cabin harms bass response.

For sure Bose is altering vehicle frequency response through equalization. Whether or not they did a good job at this is not the point. The purpose for this exercise was to see how different subwoofer orientations impact frequency response of a known system whether it be perfect or not. It is very apparent that sub position does impact lower frequency response to varying degrees.

I also suspect that Bose is allowing the frequency range of the front woofers to overlap the subwoofer to a large extent. This may be the reason behind the peaks and valley's seen in response as the sub is moved to different positions or is mounted under the cargo floor.

Next up I will place an aftermarket sub and amplifier in the vehicle to see if I can improve bass response further.

Ge0