I’m putting a smallish (200x2) amp in my car Real Soon Now. The factory head unit can drive the speakers well enough to sound good enough for background music or an audiobook, but when I really want to play music it sounds not awesome. Better than a clock radio from 1992 but not by much.
The thing is I want it both ways. When I’m playing an audio book I don’t need the amp and want it to play directly without the amp in the speaker circuit at all.
This isn’t something beyond my ability to solve, I could knock out a nice solution with relays and blinky lights and whatnot to do the job triggered by the antenna/amp line like the amp would be, then switch that from the dash. But if there’s an existing solution that isn’t stupid expensive I’d rather not reinvent the wheel.
Has anyone done this or am I the only one who would even want it?
One more important point: the amp will be using line level input, I’m going to install RCA lines for the future but the factory stereo has no low level outputs. It would be dead easy to do what I want if it did, but alas.
Any particular reason not to leave it on all the time? That sounds simpler. It’s not like the amp will consume much more power than the stock radio to drive about the same volume. Power is power, if you only play at 2W, it’ll use 2W whether the amp does it or the radio does it. The radio’s not also going to spend another 2W to “drive” the amp through the speaker output, it’s going to be milliwatts.
Personally I just ran an aux jack to RCA to my amps in the back and just use that all the time. It’s not like I have to run it at full blast all the time, if I want it quiet it remains quiet. But it still sounds better than the stock radio.
Because the sound will be different. The amp is going to put substantially more bass in it. I could fiddle with the sound controls, sure, but a push button to make it be just right is easier and faster to switch between.
I’m going to hook it up like a normal person first so maybe I won’t even get back to doing this, but it was an idea I wanted to explore.
Hmm, my subs actually take a fair bit of volume to kick in, when I’m playing talk stuff it’s barely audible and the bass only kicks in at higher volumes.
But I do have two amps, one for the speakers and another one for the subwoofers, and they have different levels set so that could be a happy coincidence.
Maybe try playing with the level and bass boost knobs? If you’re lucky, you may land in a spot where the bass is less sensitive and gives you more treble at lower volumes. Lowering bass on the radio and adding more bass boost might achieve this, counterintuitively.
Otherwise, it might be easier to switch in a low pass filter on the input, which can be done with just a capacitor. That’d be much easier than trying to switch the entire systems with relays and whatnot.
ah, you’re worried about the bass being overpowering in some voices.
Most subwoofer amplifiers have a +12v trigger wire that must be connected to the radio so that the amplifier knows when to turn “on”. Otherwise it would drain your battery constantly. It’s pretty simple to add a toggle or push button on/off switch inline with that trigger wire so that you can choose when you want it on or off.
most amps also have a configurable lowpass filter that lets you select the cutoff frequency for the sub, so it will not drive any frequencies above that. Generally setting it to 120hz or less will make it not react to most voice without needing to turn it on and off all the time. I run the 12" 400w sub in my old Honda around 90hz cutoff, as the speaker really can’t effectively drive anything higher than that, and it leaves basically all vocals untouched.
