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VW Golf MK3 (1995) Concept/SQ build

46K views 248 replies 31 participants last post by  deltasaurus 
#1 ·
So, another car, another build thread. My other/main project can be viewed here: VW Passat -00.

I have a ton of stuff just collecting dust on the shelf and I'm tired of driving a car without proper sound during the entire winter season. I wanted a car that was easy to modify and work with and a Golf mk3 was almost ideal for this. Most of the gear isn't super high-end and flashy but it will do the trick with proper install and setup. I will probably need to buy some gear anyway but I'll try to keep costs to a minimum. What I'm trying to archive is competition-grade SQ system by the use of measurement gear through the entire process. I will to get the most of every part in the system and avoid as many issues as I can in the process. This build might get technical, theoretical, weird and it's very probable it never will be completely finished. Think of it as infinite ongoing or something as I will try out lots of the stuff that were to troublesome to implement in my main build.

Equipment list (so far):

HU: Sony CD/MP3/AUX-in (dunno model nr yet - not new model)
DSP: Behringer DCX2496 (as I write this, not yet modified for 12V)
Amplifiers: Soundstream STEALTH (2x 4ch) (1x mono)
Sub: ? (Got several subs)
Midbass: Seas L18 H1224
Midrange/Widebanders: ? (Maybe Dayton RS125)
Tweeters: ? (I have 3 candidates)
Power: Banner Running Bull 70Ah AGM - Stock 90A alternator.
Cables - Power: 0GA (50mm²) Main Power cable - fused 200A.
Cables - Signal/Speakers: Audison or DIY / OFC 2,5 - 4mm² to all drivers.

Ok. I got 3 tweeters, one pair of "Amega QW1" - Swedish car audio brand. Moderately expensive kit. I have 1 pair of Peerless HDS large flange drivers and 1 pair of Vifa BC25 (horn loaded/waveguide version). The Peerless drivers are probably the best performing overall, however the size is a drawback. The Amega drivers have high Fs (resonance) of 1500Hz and sound best above 4000Hz or so, the Vifa's goes slight lower - I'd say ~3kHz with a steep crossover slope.

The tricky part is that the DCX has 6ch output which means passive crossovers between midrange/tweeter. The driver with the cleanest bottom have an edge over the others if I were to use a simple cap in series for a 6dB/oct electical filter (which might not at all have to mean a 6dB/oct acoustic slope), it's important to differentiate the two. Crossovers will be determined my measurements of both driver and environment and modeled in LEAP speaker design software to get optimal crossover component values.


Midranges: Got a pair of Dayton RS125 and RS52 domes. Also some TB w3-871s widebanders, a pair of 2" Cambridge kevlar OEM widebanders (decent drivers). Also a pair of 4" Canton midranges (plastic cone?). The OEM dash speakers measure 3,5" so any driver with a flange of 10cm(4") will fit there (IF I where to place them there, that is). A pair of Vifa TG9 would be perfect, sold those drivers a year ago unfortunately, would have to buy another pair. I'm leaning towards the Dayton Rs125, they have an exceptional lower midrange.

Sub(s): Got like 12 subs in my little stash. Leaning towards my old Atomic 12" sub, it's like 20 years old but still in excellent condition. Slightly high Q (0,55) limits the enclosure alternatives to IB/Sealed/AP. I have two TB w8-740s, mid Q drivers around 0,4 - they will work in vented enclosures as well as BP enclosures and more exotic designs like tapped horn/TL. They are 8" drivers with "standard" X-max so output will be limited in sealed/IB. Also have a 12" MacAudio STX sub, an old Pioneer 12", an Atomic 10", two Canton OEM 12" drivers, a TB w10-8...? driver, some MDS Audiophile 12" and two unknown PA 12" drivers... Suggestions? ;)

*I might get some HU with iPod support, IF I buy a HU it will probably be an Alpine or a Pioneer 80PRS.

*Might buy another widebanders/midranges if the price is right and it's good for my application. Vifa TG9, Dayton ND-series, Vifa NE-series perhaps?

*Before I even start with drivers I must determine the acoustic response at different positions in the car. The Schroeder frequency (the transition to the modal lower frequencies) and the lower octaves highest modal peak (should occur around 50Hz in this car). How the cabin gain looks is important for modeling enclosures and get the response to match as good as possible towards my target response.

-- The amps are custom anodized by Grizz Archer, bought them from him some time ago, shall be fun testing these amps. They are not available in Sweden as far as I know so they are kinda rare over here ;) --
 
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#3 ·
More ****ty stock cables removed:



Soldered new ground cables:



New cabling/fuse around battery (HU fuse directly below the big one);



Alternator cap filter (total 650uF):





Welded a fuse holder:







New alternator cable:





New ground:



 
#4 ·
The old owners where complete dumbasses, 100% morons. Dunno what they did but they managed to screw up the entire electrical system. Replaced 10-15 vital components by now. They even cut the cable to the lambda oxygen sensor, I mean wtf?

Removed crap;



Mess...



Doors:





New HU wiring:



Dunno why they cut a damn hole aside of the OEM mounting hole... idots. I will have to fix that.



Random pics below:

Disassembled Seas l18 driver (it was damaged)







Great depth in the doors, lots of space for enclosure designs.



Replaced instrument cluster (to the silver one). Replaced all bulbs to green LEDs:



Dayton Rs125, stock midrange location



RS52... damn huge flange



Peerless HDS tweet, fits perfectly :p



Some tech-flex rolls and speaker collection lol...



 
#19 ·
Dampening has arrived. Bought another car just like this one to take some parts from, I'm picking it up on Saturday. I will remove the entire dash and mod it to accompany larger drivers, but I need an extra to work with since I drive this car daily ;)

Detailed driver testing on the Seas L18 and Dayton RS125-8 is coming shortly. Still looking for a tweeter I can use. I've decided on a new headunit, the Sony won't fit my design and it doesn't got iPod support. So either a new Pioneer or Alpine HU. I really like Alpine better but Pioneer's features are better for the price (Comparing 80PRS vs 137BTi). Since I have an external DSP I'm only interested in iPod support, fast USB/iPod control, good multiline display, multiple illumination color choices to match the car and active crossovers (for the tweeters or sub ch since the DCX2496 only support 6ch output). Any suggestions aside of 80PRS and 137BTi? With some modification I could fit a 2-din HU as well.
 
#20 · (Edited)
#27 · (Edited)
Kenwood DDX-3023 | Car Audio Direct

This unit seems to be pretty cool. Kenwood usually makes decent stuff aswell.

Edit; Even better, this unit; AVH-X1600DVD - <b>NEW!</b> - 2-DIN Multimedia DVD Receiver with 6.1" WVGA Touchscreen Display, MIXTRAX, and AppRadio Mode for iPhone® 4S and iPhone® 4 | Pioneer Electronics USA.

I think I'll go for a 2DIN unit after all. Never had one so, why not? ;)
*edit*
Oops. Too late.

Glad I don't live in Sweden! LOL That radio goes for about $239 here.



I like 2dins mainly for the better user interface. I have no interest in watching video while driving. Why not move up to the 2600BT?...then you could do streaming (I know, not best for SQ, but nice for convenience and lack of cables), and hands free calling.

Price difference is like $50, IIRC (street prices)

And if you are looking at single dins, why not the Alpine 149? They sell for sub $300 and have time aligment and EQ functions built in.
Jay
 
#22 · (Edited)
I went for the Pioneer X1600DVD unit. Got an awesome price (about $350) for a BNIB.

Nice unit indeed.



I've measured the Dayton RS125-8 drivers, here's the results:

FR (Farfield, havn't figured out ARTA merging near/farfield yet)



FR into 0-15-30-45-60-90deg axis. Notice the breakup at 4kHz and the massive one at 8,5kHz. You seriously don't want that driver anywhere remotely close to that 2nd breakup. Considering power response, the driver is usable to 3kHz with a steep slope.



Same thing displayed as above, differently



CSD below. Shows no serious issues, except from the HF area (above 10kHz or so).



Burst decay shows decay as periods of each frequency instead of a fixed time unit as the CSD does. The burst decay therefore displays the "ringing" so you can compare different frequency ranges so eachother. The CSD is a bit "biased" there since a cycle at 10kHz is much shorter than one at 100Hz.

Things starts to get bad around 6-7kHz.



Harmonic Distortion at 92dB/1m equivalent. Shown as % vs amplitude.

Great performance in the lower midrange/upper midbass. Merely average above 1kHz.



Some random IMD (Intermod distortion) tests to see how it relates to the harmonic distortion. Both are non-linear distortion.

200+1500Hz (4:1ratio) - 92dB/1m equivalent.



400+3000Hz (4:1ratio) - 92dB/1m equivalent.



Verdict:

Decent driver performance, seen better. It performs good from 125-1000Hz, slightly high HD in the 1-3kHz area but it's not THAT bad. Dispersion drops off above ~3kHz. Wanna cross them before that. So basically this is a driver usable from 125-3000Hz with steep slopes both ways. A 160Hz highpass would probably be more reasonable if you tend to push them a little.
 
#24 ·
can someone explain the alternator cap filter? I know caps filter out noise, but I have never seen one on the alternator wire. How do you come up with the value to use and do you really see a benefit? It also doesnt look like it is hooked in line with the positive wire, so trying to figure out how it is wired in?
 
#25 · (Edited)
It's connected on B+ and alternator chassis ground (edit: On one of the pictures it's not connected, must have taken it before I connected it lol). The cap is composed of 2200uF+100uF+1uF+100nF+4,7nF in parallel. The a filter "ladder" eating up much of the HF overlayed on the DC output. The cap acts like lowpass and not like a notch or something.

Placed a similar cap over the terminals of a Alpine PDX amp. The noise is clearly reduced as seen on the picture below. Seen AC reductions below 1kHz with a $1 DIY cap like mine. A friend had alternator whine in his setup for some reason, placed a 470uF cap over the alternator and the noise was reduced by 50% or so.

 
#29 ·
Started to apply some CLD and foam today. I noticed it smelled like gasoline in the trunk, removed the cap to the fuel pump access and it seems like the previous owners (idiots) hadn't bothered to put back the gasket correctly which sealed the big hole to the tank. I had to fix that little issue so I never came to finish my dampening work today, which I had planned... Well anyway, here's some pics;







Aluminum foil tape









The fuel pump/tank is below that silver-ish round cap btw.
 
#32 ·
Sure. I'll make a circuit diagram later. It's nothing complicated though.

Taking care of the noise at the source is more effective. The car's ECU doesn't mind getting a clean DC feed either ;)

Sent from my Samsung Galaxy 3 via Tapatalk.
 
#36 ·
excited2see whadcha gonna make of this!!!!
always found the golf mk3 a nice n solid car to install .
Indeed it is. Wonderful car to mod and build audio systems in. Everything is quite easy and uncomplicated, which makes the actual modifications funnier/easier to make. I had quite a few frustration moments with my newer Passat, there's so much crap everywhere so it sometimes makes an seemingly easy modification almost impossible to archive and it's simply annoying. This car is refreshing because I can do almost everything I want without hassle.
 
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