Leaderboard

Alright here comes big post about my sound system design. I’ve spent months researching car audio and coming up with a design for the system, I’m gonna do a brain dump of the whole process, but the end result is this: Tweeters: SB accoustics SB21SDCN-C000-4 Midrange: Morel MM2 Midbass: Studio Integrity TM8 Sub: none Amp/DSP: Helix V Eight MK2 Head Unit: Sony AX5500 I love music and all things audio and set out to design the best sound system I possibly could for the Datsun. To make a sound system in a car sound good, rather than just loud, there’s a bunch of issues that need to be overcome that aren’t present when you listen to 2 speakers in a room: Time alignment (listener is not equal distance from both speakers) Many sound reflections causing EQ issues Directionality - music is designed to come from in front of you, but there is not much space in a car cabin in front of the driver for speakers The first 2 of these issues can mostly be solved with something called a Digital Signal Processor (DSP). A DSP a little computer that processes the music signal before it’s sent for amplification, and it does this separately for each individual speaker. This allows each channel to be EQ’d separately, and certain channels to be delayed in time so that the sound arrives at the listener from all speakers at the same time. The other thing that the DSPs made by Helix allow you do is a “2 seat tune” which is a way to make the music sound good for both driver and passenger, rather than tuning the whole system around the driver. The general concept of this is for the center information in the music to play out of a dedicated center speaker, rather than being a combination of left and right playing at the same time (which doesn’t work well cause time alignment can’t be done for passenger and driver at the same time). 2 seat tune was a really important thing for me cause since my partner is allowing me to spend all this money on a sound system, I want it to sound as good as possible for her too, not just myself. The third issue to be overcome is that music is designed to come from in front of you and often each instrument has a distinct placing on this “sound stage” in front of you, from left to right, and close and far. This is hard to achieve in a car cause there is limited space for speakers in front of you. Door and kick panel speakers are an improvement over speakers in the back, but are still a big compromise to sound quality. There is one factor working in our favour though and that is that humans can’t perceive direction in sound below around 200hz. So we can design a split system where the above 200hz information plays out of a speaker pod in the dash or attached to the a pillar, and the low frequencies play from anywhere else. And this is indeed what high end audio builds do. So with that in mind, I had 3 options: Cut the dash to put speakers in (ugly) Build a dash or a pillar pod for the speakers (not really possible with the sharp slope of the windscreen and also ugly) Put the speakers in a sub optimal position like doors At this point you’d probably wonder, why bother? And especially why put a good sound system in a 3.1L stroker Z which already sounds insane and is pushing legal Db limits? Reason is… for science. I wanna push the envelope and see what’s possible. So I was coming to terms with having to cut big ugly holes in the dash for my midranges. Then I came across a very special speaker, the Morel MM2 midrange. Although these don’t quite go down as low as the target 200hz, they’re absolute tiny for a midrange, so small that they fit into the dash cowl area up front near the windscreen. So the idea became - mount the speakers into the dash cowl. After some testing, keeping the dash cowl in one piece wasn’t possible, it’s hard enough getting that thing in and out already, with speakers mounted in it would be impossible to install without removing the windscreen. So I decided to cut up the dash cowl and make mdf speaker panels for the sides so everything fits. Lachlan’s shop helped do the cuts to the cowl for me and got the circles for the speakers perfect. While I was at it, I also made a speaker pod for the center. Photos attached for how these ended up looking. I think these turned out okay given I have zero prior woodworking experience. I’m mostly just happy everything fits and works cause it was playing with fractions of a millimeter trying to get it all to work. But I’m not completely happy with them and I’ll have another go again some time and make them nicer. For the tweeters, I went with sb accoustics SB21SDCN-C000-4. Reason being crazy good off axis peformance, aesthetics, rave reviews, and low price. For the low end, I’m going with a stereo integrity tm8 8 inch midbass, which will run from ~60hz to 500hz. These will be mounted into the riser behind the seats and will be mounted in an “infinite baffle” setup. I decided to go with 8 inches rather than traditional 6 inches in a 3 way setup cause 8 inch covers the frequency range I need <500 Hz way better, and the car audio forums are going crazy for these speakers. I’m going to try this setup first without a dedicated sub woofer cause I’m thinking I’ll be getting more than enough low end from the 8 inchs for the type of music I listen to. Other goodies being added in Sony touch screen head unit with apple car play Reverse camera Helix controller for volume, tone, and preset selection (1 vs 2 seat tune) Next step now is to get the professionals to install it all. I’ve reached the end of the road in terms of what I’m comfortable doing myself and I don’t mess with electrical stuff.