• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Car audio build... pic heavy!

Joined
Dec 13, 2019
Messages
63
Likes
44
Location
Nottinghamshire, UK
#1
So I asked if anyone wanted to see my car audio build and got a few yes answers, so here we go.... Hopefully this is ok in here as its

I will be building a relatively high end system for EMMA car audio sound quality competition.

My background is I am a multi time up and European champion and record holder in dB drag (how loud is your subwoofer<s> competition) but I’ve always been involved in car audio and cars one way or another and my career has revolves around being a car technician/mechanic and auto electrician and now work gainfully for Nottinghamshire police as the force in car technology engineer, so daily I install/fix ANPR, tetra radio installations, trackers and anything 12v they want doing in a variety of vehicles.

My base vehicle is a Vauxhall Corsa 1.4 petrol, it was chose purely for its quality’s for doing competition.

so for a start my kit list...

Currently I have an alpine source unit which has served me well but in terms of detail and frequency response it got showed up badly by a topping and my iPhone XR, now I have acquired a clarion nx807e double din with Apple car play, Bluetooth, cd/dvd and most important a 96khz optical output so I can go digital from cd and phone to processor.

So the processor is a Helix DSP pro 2, optical and coax in, also usb or Bluetooth streaming (both of those are with hec extension cards), also 8 channels of analogue in, then 10 channels of outputs that are fully configurable, 30 band of EQ for each channel (shelf filters, parametric, graphic, all pass are all doable) high and low pass crossovers, phase in 40 steps from 0-180, and a phase 0/180 swap button also. Also does time alignment in 0.1ms (0.4cm roughly) steps which is essential in cars

to be continued...
 
Joined
Dec 13, 2019
Messages
63
Likes
44
Location
Nottinghamshire, UK
#3
So currently I have class ab amps in the form of 2x ground zero uranium 4.150sqx 4 channels and a single uranium 2.250sqx 2 channel, these are a little unusual in car audio lands as they have a variable bias, it’s not class A full on, but It increases the bias towards class A, Ive not really played with it... and I won’t be as I now have acquired a rather high end Zapco 150.6ap, the top tier of zapco amplifiers

It’s a straight up amp with no crossovers, just six ins, six outs with 6 gain pots

I will probably still use the 2.250 if I need to for subwoofer duty’s, but I will try and run 2way stereo plus a single 10” sub for the front end all from the zapco if I can... but if I need to run a pair of 8” midbass on the dash and a subwoofer in the rear I will

As an addition I will add that I measure with both a umik usb mic and also a Dayton xlr mic with m-audio mobilepre interface (I find the latter works better for phase and time alignment measurements using rew due to an all in one box solution - I’ve had timing drift due to using pc sound out and usb card for the mic) for actual audio measurements both are calibrated so I use either, the umik is obviously a bit nearer for incar use as it is one lead and way tidier!

to be continued...
BC53601C-2141-494B-A8BC-44317BC73478.jpeg
9634D014-0826-4C12-BD6F-7F951747F660.jpeg
85761D57-7E86-4959-A066-A3CB6FE4C9BB.jpeg
D3338332-991B-48BB-9D2F-16D20A8A4DED.jpeg
 
Last edited:

RayDunzl

Major Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
8,117
Likes
5,218
Location
Riverview FL
#4
My background is I am a multi time up and European champion and record holder in dB drag (how loud is your subwoofer<s> competition)

Now that is an activity for which I fail to understand the appeal...
 

Hemi-Demon

Active Member
Joined
Jan 17, 2019
Messages
140
Likes
80
#6
I love some Zapco amps. The helix dsp is the standard these days, I'd love to see one actually measured my amirm.
 
Joined
Dec 13, 2019
Messages
63
Likes
44
Location
Nottinghamshire, UK
#9
are Zapco amps better than Focal?
the top of the line focal amps are 3-4 times cheaper than the zapco ap range (the above amp is just shy of $2k I think in the states?) so I definitely would’t compare the two, (perhaps the zapco st-4/6sq maybe) but saying that I’ve never heard the focal, but I have heard the zapco and put it in the top tier against amps that cost twice as much if not more
 

pozz

Machine
Forum Donor
Editor
Joined
May 21, 2019
Messages
1,264
Likes
1,811
#10
@Dumdum I was fully expecting you to post your amp of choice as being able to handle 10kW into 1 ohm. One of those showstopping car amps.

BTW, what kind of microphones are used to measure SPL accurately. From what I know the championship cars boast >160dB SPL output.

@RayDunzl If you ever look inside one of those cars I think you'd be impressed. Even if you don't stay for the show.
 
Joined
Dec 13, 2019
Messages
63
Likes
44
Location
Nottinghamshire, UK
#11
@Dumdum I was fully expecting you to post your amp of choice as being able to handle 10kW into 1 ohm. One of those showstopping car amps.

BTW, what kind of microphones are used to measure SPL accurately. From what I know the championship cars boast >160dB SPL output.

@RayDunzl If you ever look inside one of those cars I think you'd be impressed. Even if you don't stay for the show.
Been there done that, my old little street max 1-2 dB drag car had 4x 5kw amps off a single ‘mutant’ 2000 dollar battery that measured approx 14000rms give or take into approx 1.1ohms per amp (resting load was 0.25ohm per amp)

I had 2 3” coil subs which held up pretty well for approx 80-100 full pelt burps at around 72-73hz

my scores were 164.1db for my pb, I was in the baby class with a wall with two 18” subs behind the b-pillar, the world record was actually 163.9 at one point for my class when I was doing a 163.4 at the euro finals... 0.5db sounds close, but in reality it was a world away with the exponential curve to gain every last tenth!

the 20cu ft enclosure was made of steel box section 20x20mm with a 2mm wall just stacked up and welded with 3 deep ribs at 1/3 and 2/3 height on the sides (it didn’t flex), birch ply and t-nuts were used for the front face, the rest was box with filler/fibreglass mix over the top to make it smooth

the mic is now a pressure sensor in a small plastic enclosure on sucker cups to the screen, it has measured consistently to over 183db I believe (definitely 182db as I’ve seen and witnessed that many years ago)

I have also been a judge at the dB drag world finals in the states in 2005 and was a judge in the U.K. for many years

many years ago I would’ve been showing 10kw amps off, but now I’m doing sound quality competition I am enjoying the more refined side of things :)
 
Last edited:

pozz

Machine
Forum Donor
Editor
Joined
May 21, 2019
Messages
1,264
Likes
1,811
#12
Been there done that, my old little street max 1-2 dB drag car had 4x 5kw amps off a single ‘mutant’ 2000 dollar battery that measured approx 14000rms give or take into approx 1.1ohms per amp (resting load was 0.25ohm per amp)

I had 2 3” coil subs which held up pretty well for approx 80-100 full pelt burps at around 72-73hz

my scores were 164.1db for my pb, I was in the baby class with a wall with two 18” subs behind the b-pillar, the world record was actually 163.9 at one point for my class when I was doing a 163.4 at the euro finals... 0.5db sounds close, but in reality it was a world away with the exponential curve to gain every last tenth!

the 20cu ft enclosure was made of steel box section 20x20mm with a 2mm wall just stacked up and welded with 3 deep ribs at 1/3 and 2/3 height on the sides (it didn’t flex), birch ply and t-nuts were used for the front face, the rest was box with filler/fibreglass mix over the top to make it smooth

the mic is now a pressure sensor in a small plastic enclosure on sucker cups to the screen, it has measured consistently to over 183db I believe (definitely 182db as I’ve seen and witnessed that many years ago)

I have also been a judge at the dB drag world finals in the states in 2005 and was a judge in the U.K. for many years

many years ago I would’ve been showing 10kw amps off, but now I’m doing sound quality competition I am enjoying the more refined side of things :)
Very, very cool. You mind posting a few pics?

There's the equivalent of a car sound quality competition? How are those judged usually?

How much do the designs vary? Cars are pretty uncomfortable to mount anything like a 6" woofer. I'd say the main reason most car audio suffers is because those drivers have to sit in the door around your feet. I've heard Harman did some interesting work at Lincoln but I never got around to looking at it.

Do you also find the same sort of audiophile talk in the car audio world about gear?
 
Joined
Dec 13, 2019
Messages
63
Likes
44
Location
Nottinghamshire, UK
#15
Very, very cool. You mind posting a few pics?

There's the equivalent of a car sound quality competition? How are those judged usually?

How much do the designs vary? Cars are pretty uncomfortable to mount anything like a 6" woofer. I'd say the main reason most car audio suffers is because those drivers have to sit in the door around your feet. I've heard Harman did some interesting work at Lincoln but I never got around to looking at it.

Do you also find the same sort of audiophile talk in the car audio world about gear?
sound quality is very much single seat judged these days, generally the car will have an evenly spaced stage, you sit off centre, but the centre stage will be the centre of the windscreen, with left, right, left centre, right centre evenly spaced in a good car

We use various well recorded technical tracks and the judge uses these to score spacing of the five positions, basically the cd plays vocals and various instruments in the five locations and they should all be in alignment in each of the five locations, points are deducted if for example on the centre test the triangle smears to the right of centre or the guitar seemingly moves as the frequency of the two notes is slightly different and the left right balance isn’t quite perfect

there are also technical music tracks, again well recorded by a German sound engineer/composer who makes a point of setting up each track to show up and make light of every and any inadequacy in the system

for example there is a sub bass test track with the pitch altered on a small wooden cigar box to create a track that plays at 100hz, then 80hz, then 60, then 40, then 30, your sub bass should appear to come from in front of you... you get markedly of three for each of the sounds presecence, is it around you, is it in front of you, so if it plays 30hz but it’s felt to be around you rather than in front you would get 2, if it sounds like it’s in the screen you’d get three... I will be using a pair of seas 22cm midbass drivers on the dash in a sealed enclosure to attempt to get as much of it on the dash as possible... most cars pull back on 30/40hz unless they are timed and phased to perfection, often with a front sub in the dash or glovebox area and no rear sub... but even then the lengths of the car can make it sound like it’s around you

They also evaluate stage width, depth, tonal accuracy of sub bass, midbass, mid range and treble using the various musical tracks

I am cutting my teeth the last year with a van which was acoustically awful, my new car is far better off the bat, I’ve literally bought a car purely with the intention of doing competitions, I wouldn’t normally be driving a Vauxhall corsa, but needs must :)
 
Joined
Dec 13, 2019
Messages
63
Likes
44
Location
Nottinghamshire, UK
#16
You did the welding yourself? I'd imagine the joints have to be done really well to hold up.
Me and a few mates took it in turn, an inch of weld with good penetration will break at approximately 1 ton, so we basically stitched it up as you can see with welds back and front every 12” but staggered so it was immensely strong! It also had a single brace between the rear wall of the enclosure and the edge of the massive port (the enclosure was roughly 32” tall internally and the port was about 15” wide, so approx 480 sq ins with a length of roughly 6”... but you can’t calculate it normally as the port is using the box side as a side of the port so it’s longer in reality)
 
Joined
Dec 13, 2019
Messages
63
Likes
44
Location
Nottinghamshire, UK
#17
So the current car...

A70AE411-0F63-491A-B58D-13F241CDB82D.jpeg


So currently I have cut the top section off the dash to make way for three enclosures, currently I have very undersized enclosures for my two sb acoustics sb17mfc-4 drivers of just under a litre to test various positions with the back wave trapped, the result is a rather peaky 17cm driver i can move and test to try various locations for reflections, and to test where the brain perceived the location of the sounds at various frequencies

I basically cut an18mm baffle with a 5mm recess for the driver, then copied the baffle into 4x 18mm mdf rings, then cut just the outer in 12mm birch plywood to make a very compact 0.7l enclosure, once Ive decided on a location I will then make an 8l enclosure at each end of the dash closely relating to the angles that are best in the test... which as it happens were as the above picture :)

D1F298B8-AAAE-419B-9FA4-6B3749F1F9B6.jpeg


I also use a fixed mic position perfectly between my ears for adjusting timing to perfection using my Dayton mic and m-audio interface (unfortunately the headrest kind of gets in the way so I acquired a spare headrest and made a hole :) )

B9BAF59A-F6E7-44B9-B39F-8436E84EAB3E.jpeg


I’ve also knocked up a simple fuse holder for the rear of the car, as you can see it takes four maxi fuses for second battery and the zapco (plus two spares for future expansion) and a single midi fuse which then feeds a small 6 way blade fuse fuse box which supply’s the dsp, lighting once in and the Stereo, plus it will handle two 12v remotes, one from stereo to turn the dsp on, and also one from the dsp to the amplifiers also, you can adjust the timings of turn on and off on the dsp software also
 
Joined
Dec 13, 2019
Messages
63
Likes
44
Location
Nottinghamshire, UK
#18
Tried another variation and changed the plan for the side enclosures... I began with the following...
6677B94A-C8BE-4115-890B-4F7CFBBD295C.jpeg
88AD53FC-712B-4CD1-B981-C35C7A6AB52F.jpeg


then decided i was making it harder than I needed to and could simplify it a lot more, so I then cut a ‘shelf’ shaped to the sides of the car and will now make a couple of enclosures which aim in the same orientation, this will make symmetrical enclosures and the centre section a fair bit easier to form and make it look a fair bit nicer, I’m still undecided on how to fill the midbass void of the stereo below 100hz, but in the mean time I have some satori mw16r-4 on there way now I know where the drivers will sit

I also have a mystery present on its way from randy bagby in the states, in case any of you know home audio speaker designers... yes he is Jeff bagby brother and uses sb acoustics heavily in his designs among others, he just asked me for my address and said he’d send me something... literally no clue what’s gonna be arriving, top bloke anyway :)

so it now looks like this

023A5485-216B-4432-B1D7-039372EEBF41.jpeg

the driver orientation is too far forward and has too much interaction with the drivers side glass, this in effect makes the brain think the sounds source is somewhat outside the boundary of the speaker at certain frequencys... which gives added width... woohoo... but note I said it’s frequency dependant, this in effect diffuses the centre image and is in reality bad... the number of ‘professional’ installers who say the sound comes from the speaker on some songs, from the side mirror on others, and way outside that point on others... just says to me my centre image is diffused and the position of instruments that should be placed accurately will not be so accurate if they share freqs from the three locations

it’s a catch 22, you want the most width, depth, height and stability in the stage, but it’s all a balance using reflections to give the three, but without wrecking the fourth...

it amazes me the positions I see speakers in, I just know from the dispersion characteristics of the speakers the centre will be wide, and certain freqs dragged across the screen from the passenger side (this is the hardest side to get correct as the drivers side you are sat in front of the drivers generally so reflections are up and down... as long as you can keep the side windows out of the equation to a greater extent :)
 
Joined
Dec 13, 2019
Messages
63
Likes
44
Location
Nottinghamshire, UK
#20
Wow you reformed the entire dash. Are you going to finish that will fiberglass?
It will mainly be 12mm birch ply to make a structure with some fibreglass filler and maybe sheet reinforcement and then a finer resin/body filler mix known as milk shake around the inside to make sure it’s 100% sealed

The plan so far is 7l side pods for the midwoofers (sb acoustics satori mw16p-4) then test a variety of positions and aiming for the tweeters to see how reflections effect the sound

Then when I’m happy with those build those into the A-pillars trims you meet the corner midwoofer pods neatly, then it’s start on the heavy lifting... midbass proper... in the centre of the dash, I may use sb 23cm small subs as they will be playing 100hz down, but I also have a set of seas 22cm drivers in stock already for experiments

Thinking the small 8” ‘subs’ will dig a little lower and if I can use only them and no sub in the boot I will be a very happy bunny... one of the tests on the competition disc is a heavily mixed small wooden cigar box used as a drum I think, and it plays at 100hz, then it’s pitch is shifted to 80, then 60, then 40, then 30... 60/40/30 are hard to get sounding ‘upfront’ and if it pulls back you then lose marks, every one counts at the level I’m aiming for.
 

Similar threads

Top Bottom