MR2 Roadster Owners Club

The Workshop => Audio / Security / Electrical => Topic started by: steveash on March 3, 2020, 19:51

Title: Small amp without a head unit
Post by: steveash on March 3, 2020, 19:51
I didn't feel the need for the slightly ropey aftermarket stereo fitted to my car so sling it in the name of weight saving and blanked off the hole. It would still be nice to occasionally connect my phone to the speakers so I wondered if it was possible to connect a small (and light) amp directly between the two as I don't really have need for a head unit.

Has anyone come across such a thing? I had a quick look on Amazon and found some 12v Bluetooth options (worryingly from a brand called 'Nobsound') but they seem to be designed to be connected to a mains transformer rather than a car battery.
Title: Re: Small amp without a head unit
Post by: shnazzle on March 3, 2020, 20:06
I have one of these. 
Just needs 12v feed from battery (with fuse) and then just hardwire the speakers into the green blocks.

Might need a more powerful one than this particular one to drive the speakers raw. But they're there between 5 and 20 quid. Don't know what impedance the stock speakers are.
Title: Re: Small amp without a head unit
Post by: steveash on March 4, 2020, 01:10
Quote from: shnazzle on March  3, 2020, 20:06I have one of these.
Just needs 12v feed from battery (with fuse) and then just hardwire the speakers into the green blocks.

Might need a more powerful one than this particular one to drive the speakers raw. But they're there between 5 and 20 quid. Don't know what impedance the stock speakers are.

Thanks. I'll have to get one and have a fiddle around. With modern phones the head unit seems rather unnecessary.
Title: Re: Small amp without a head unit
Post by: househead on March 4, 2020, 08:37
Quote from: steveash on March  4, 2020, 01:10With modern phones the head unit seems rather unnecessary.

Yes and no ... the headunit can be legally fiddled with on the move. My understanding is that even in a cradle, the phone screen / buttons can't be legally touched?
Title: Re: Small amp without a head unit
Post by: steveash on March 4, 2020, 19:45
Quote from: househead on March  4, 2020, 08:37
Quote from: steveash on March  4, 2020, 01:10With modern phones the head unit seems rather unnecessary.

Yes and no ... the headunit can be legally fiddled with on the move. My understanding is that even in a cradle, the phone screen / buttons can't be legally touched?

Good point! Although most phones can be voice controlled these days, it is a bit of a struggle!
Title: Re: Small amp without a head unit
Post by: househead on March 4, 2020, 19:49
Quote from: steveash on March  4, 2020, 19:45
Quote from: househead on March  4, 2020, 08:37
Quote from: steveash on March  4, 2020, 01:10With modern phones the head unit seems rather unnecessary.

Yes and no ... the headunit can be legally fiddled with on the move. My understanding is that even in a cradle, the phone screen / buttons can't be legally touched?

Good point! Although most phones can be voice controlled these days, it is a bit of a struggle!

Yep, but I have privacy issues so on my iPhone, Siri is activated only by a button, which in my case is on a Sony remote control stalk. Pretty handy with a CarPlay headunit saying stuff like "play Driving Tunes playlist" and "what's the weather like in Brighton?".

I hate the idea of my phone listening all the time (which it must do in order to respond to a voice prompt "from cold"). Anyway, I digress :D

Don't worry, I won't tell the boys in blue on you :D
Title: Re: Small amp without a head unit
Post by: shnazzle on March 5, 2020, 18:53
I just hooked up my little sound board to my 6ohm speakers and a 12v input.
Quite surprised actually, it drives the two speakers!
But... Not well.
If I remove one, it drives it absolutely fine. Clean bass response down to about 30Hz. More than low enough for stock speakers. Seeing as the stock speakers are 4ohm, I reckon this thing has a chance.
Worst case scenario is that you get a mini amp, feed this in, and then out to the speakers. The amp would fit easily in your glove compartment or take up very little space under the hvac controls. Along with the module.

Hmm...

IMG_20200305_184239.jpg
Title: Re: Small amp without a head unit
Post by: shnazzle on March 5, 2020, 19:33
Alpine ktp-445u looks interesting to add to this. You have to do the wiring anyway so then you can fill your boots
Title: Re: Small amp without a head unit
Post by: steveash on March 7, 2020, 11:20
Quote from: shnazzle on March  5, 2020, 19:33Alpine ktp-445u looks interesting to add to this. You have to do the wiring anyway so then you can fill your boots

The ktp-445u weighs 1.1kg and isn't small or cheap so might as well fit a head unit. I think a little Bluetooth amp should fit the bill if I can work out the wiring. Trouble is, my car is 80 miles away and I won't get to tinker with it for another month or two.
Title: Re: Small amp without a head unit
Post by: shnazzle on March 7, 2020, 13:01
Quote from: steveash on March  7, 2020, 11:20
Quote from: shnazzle on March  5, 2020, 19:33Alpine ktp-445u looks interesting to add to this. You have to do the wiring anyway so then you can fill your boots

The ktp-445u weighs 1.1kg and isn't small or cheap so might as well fit a head unit. I think a little Bluetooth amp should fit the bill if I can work out the wiring. Trouble is, my car is 80 miles away and I won't get to tinker with it for another month or two.
Eh? Maybe I linked the wrong thing. It was tiny. Not cheap you're right there.

It looks small here but you're right, on other pics it almost looks like a full size amp
https://images.app.goo.gl/xj9cN3mKmBpgHXQw5