have spent the last few days planning out and executing a sound upgrade to our car. everything was going fine up until we started and step 1 took literally 6 hours lmao

can't wait to have this finished!!! have some Progress Pics

(we stopped taking photos at about 4am when we were so tired and exhausted we just Forgot)

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Day 2

can't be bothered to strip all the EXIF just yet but we're almost there. everything is wired up, no fires, etc. but we're getting some very interesting readings from our multimeter. here's our notes so far

Testing frequency response to voltages at 15/40 HU volume

OEM Sub (at the driver)

Hz	Voltage
20	.501
60	.582
80	.191
150	.068
250	.022
440	.008

OEM Rear left speaker (at the driver)

Hz	Voltage
20	.004
60	.067
80	.069
150	.111
250	.052
440	.144

At the high level input on the amp, tapped from OEM Rear left speaker near the factory amp

Hz	Voltage
20	.004
60	.058
80	.087
150	.117
250	.054
440	.151

At 30/40 HU volume, playing a 50hz sine wave

V=P⋅R−−−−√

150W⋅4Ω−−−−−−−−√=24.494V

Target voltage out from amp should be 24.494V

On minimum gain(5V), the amp was outputting 0.6V. On highest gain(0.2V) it was 1.374V.

The high level inputs while playing 50hz sine wave on 30/40 HU volume was:

• Right channel was 0.278V
• Left channel was 0.276V

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Day 3 (the final day)

just got back from jaycar, and bought some of these

after taking yesterdays readings, we decided instead of sending our speaker tap into the sub's high level input, we would send it into the low level input. when the unit was at it's theoretical max volume before distortion, it was only sending 0.277V to the amp. that's well within the low level input range (of about 0-4V?) so we instead hooked it up to a couple rca cables and hey presto, it's not as quiet anymore!

at 30/40 HU volume, playing a 50hz sine wave and measuring the amp output with a multimeter, it was outputting 1.7V!!! which is already higher than yesterday when it was at it's most sensitive. we did the normal thing of slowly turning up the gain until it reached it's target voltage of ~24.49V

150W⋅4Ω−−−−−−−−√=24.494V

our amp goes from 5v all the way up to 0.2V, and we managed to hit the target output at around 0.35V sensitivity.

and that's it, project done! we need to tidy up the boot, tuck the cables away. put some trim back on in the cabin, and flex loom the power cable under the bonnet.

aside from that, an upgrade that needs to be done soon is replacing our flimsy ground connection that we (basically failed to) soldered to the terminal with a screw and square washer. unfortunately the ground's one was missing when we got the amp, but no worries. apparently they are just like M3 or M4 screws.

something to worry about another day! fuck yes! we have a sbamp! sbamp!