Muu83

Thought I'd share a little project I've been working on for a upgrade to a 991.1 with SPP stereo.

To head off the first question that'll pop up, why not just buy the Musicar system? Well a few points; I'm in the UK so the car is RHD and also has a Porsche tracking system that's also in the same space and held in with fasteners with snap-off heads; I wanted control over the install, to tune it how I want; cost wise sending Danish & Italian parts to the US and back makes the tweeters costly as we'd have to pay about 25% atop once you factor in VAT & customs fees; It's a fun project and I have a background in audio. If this isn't 'fun' for you, and you're LHD just pays the monies and order up from Musicar or SIM.

This is the amp in my car...



So first stop was the tweeter, the MD102 that everyone uses as not looking to reinvent the wheel here, and the factory unit is hideous sounding. So bought some for £185 from Germany and pulled them apart to measure up:


Quick CAD model in fusion360 of the driver inside:


After many iterations this was the design I settled on, has the pretty top with waveguide and enclosed rear like some of the other printed versions I've seen:



Sent them off to print:




Assembled with driver - you can't see the press in M4 inserts before I put the rear clam in place.




Input loom made:


Fitted to car:


With grille:


Next.... the amp

Muu83

My goal was to cut nothing on the car so it's 100% plug and play, and could be returned to stock after if need be. Eagled eye'd will notice the DTM plug on the tweeter, that's because I'm running new lines to them to run active.

My amp of choice is also a mosconi but the smaller more efficient D2 80.6 DSP, easier to package and less heat with small power footprint considering where the power has to be fed from. Sure audiophiles will want class AB and tell you about their valves heating the lounge, but in the pro audio space class D is king now - have a look at the dynadio 'core' range of pro monitors. I come from an audio engineering background in TV and prefer a more linear tone anyway, and I'll be running a HK 'house curve' on this build.

First step is to understand the HU output:


This is based on lifting the signals from the factory plugs - note I found the mating pairs for the connectors so not a snipped wire in sight.


What initially caught me out is the output is balanced, the two lines are both signal carrying but in different phase to each other, like pro gear on XLR. The point being that induced noise (the signals run in a loom the thickness of your wrist) is introduced evenly into both lines, then rejected when one line is inverted and the two signals summed. Rather than your normal consumer RCA with signal and GND/Shield. The mosconi is advertised as having 'differential' inputs but here is the catch, only in speaker 'high' level mode! So you're left with two choices; run the amp in low level mode and get the gain structure you want, but it'll be really noisy; put the amp into high level mode and you'll get noise rejection but even with the HU on max and gains all the way up you'll have very little output. Musicar are smart and they have modded the amp, some other installers less so and either leave the ASK amp in play to get speaker line or just have a crap gain structure and pull back levels downstream of the DSP.


This is a common problem going being pro and consumer gear and usually I'd dig out a Neutrik box to move between impedance domains or from balanced to unbalanced etc. This is what I came up with:


Built into a new input loom:


Also finished the output loom:


Amp needs a mount tho:



Fitted in the car...

Muu83

Ok this one is a RHD thing, the amp is under the right hand seat (drivers here) like everyone else but the power distro is in left hand floorwell:



What a pain in the bum that is, as it's the same unit as the LHD cars but mounted back to front so it has to be removed and flipped to get access to the posts. I then had to fish the power line over the tunnel and through the plastic conduit that keeps the loom clear of the steering column. All tied into the factory loom and back to the amp.

Also of interest is the frequency response of the amp (I ran this test not realising i had +2 bass and +1 treble on the HU) but the falloff is much the same I imagine. Starting at 10 clicks from silent, adding 5 clicks at a time:

SF Neunelfer

WOW, Excellent job!!

kingerm

Very encouraging. Thanks for sharing your process.

Muu83

Thanks guys, happy to open source any designs or calibrations etc. Will also gather up a list of honourable mentions, as some other DIY builds had some very useful info in them.

PTS-BRG

where are you located?

Muu83

London suburbs

Porsche_nuts

Super nice job. Must sound fantastic.

flgfish

Very cool.
In the US, the ASK amp is on the passenger's side (right side) and so is the power distribution. That's convenient. I put a sub amp under the driver's seat and had the same power run around the center tunnel fun as well....
Where did you get the connectors to interface with the ASK amp input & outputs? I ended up buying a cheap Cayman amp off ebay and removed them from that...

Muu83

yes and the backwards distribution box is a nice little added extra on that job

How did you get on setting the amp gains?

So the input is a VAG item, so can be bought new with pins, can dig out the part number:




Output is the same as the BMW F10 albeit with different Ident pins, but can easily be made universal with a sharp blade. Technicpnp for this one:


Technicpnp -
https://technicpnp.com/product/logic...-applications/

flgfish

Man, I searched all over for that thing. Found the actual part number, but Mouser & Digikey wouldn't sell them to me because they're "private parts" or some nonsense... figured Tycho or Amp, can't remember who, must have had a deal with Porsche to only sell to them or their designees.

I have a thread on the build over on DIYMA... never did make a thread here.
https://www.diymobileaudio.com/threa...arrera.415081/

Setting the gain was no problem at all. I actually just followed the A-F Helix recommended procedure in the manual & never touched them again (I used a Helix V Eight)... don't remember if it was 10k Hz at 3/4 volume, something like that...
I routed the PCM outputs to amp line level inputs, front and rear, and it worked out swimmingly.

Muu83

So had a tip off to go looking for hands free kits to rob for parts, and ended up pulling that thread until I found that. Took a punt and ordered it, and it fit nicely once the thin fins that ID different versions we're trimmed out (not the 4 lugs that seat it, but keys inside).

Ah so the mosconi line inputs and other amps I've seen people complaining about at line level range of gain lack the differential input, so I built this:


Am aware of your work, you're on my honourable mentions list of builds I studied.

​​​Not setup my EQ yet with the umik-1 and rew, but already it's sounding great with just the amp and time alignment.

Bud Taylor

Hey your rennmount is on the wrong side, oh wait.

Muu83

Just ordered up some new door drivers and James and Rennspec has an idea plug and play door solution, adapter rings and cables mean no cutting.