Hardware Review: 41hz.com Amplifier Kit
As some of you may know I was looking to find a good solution for an 'in dash' amp that wasn't built into a headunit (I've got nowhere to put one since the screen is going there!)
I considered trying to get one of the mondeo amps but had a hard time finding one and wasn't sure if it would fit behind the dash anyway!
So.. new plan, a few people suggested the amps from 41hz.com so I checked out their site and ended up buying the AMP9 12v Kit.
This amp is 4x60w and its pretty damn small (50mm x 160mm)
Two days after ordering my kit arrived from Sweden, I was pretty impressed with the delivery speed and couldn't wait to get stuck in building up the kit!
I opened up the package to find all the components neatly packed and then it dawned on me... what have I let myself in for, I'm no master solderer by any means.. but I was willing to give it a shot!
After a quick breakfast and a good study of the bill of materials to make sure everything was there I got stuck in soldering the components onto the bottom of the board... this is around 1 hour in, a long way to go yet!
Soldering these components definatley gets easier as you go along, but if you've not but much component soldering before then I'd recommend you get the SMT solder kit thats available from 41hz, this is simply a dummy board with components to help you hone your skills
Here we are at around 3 hours in, bottom side is now finished and I'm around half way through the top of the board..
One you get past soldering the Tripath chip, which I found a little tricky due to the closeness of the contacts the rest of the top is fairly plain sailing... that is until you reach the Toroid Inductors!
The Toroid Inductors are the 8 Rings you see on the top of the board that are wound with wire, when the kit arrives you get the 8 rings on their own and 8 strips of wire.. you know whats coming next
You have to wind each toroid with 52 turns of wire.. it took me around 25 minutes per toroid, so that was done while watching some evening tv.
One thing I will say is that if you keep the center of the ring tight with your winds you do get exactly 52 winds before you are back at the beginning, makes life much easier when trying to count them!
You may want to put a plaster or something over your working fingers while winding the toroids as after winding 8 rings you fingers get rather sore!!
After another hour or so I finish up the top of the board.
In my haste to test out my work I decided to hook the power up via croc clips onto the board via my bench PSU.. BAD IDEA!!
I hadn't realised that all along the edges of the board (between the layers when you look side on) there are copper tracks exposed, this must be connected to ground since when I fired up the amp for the first test it shorted with the positive croc clip
Once I realised my mistake I soldered up an ISO connector for the power and audio outputs since this is what I'd be using in the car anyway..
I got quite disheartened on the second test of the amp when I didn't get any output.. fearing I had burnt something out with my earlier escapades I started checking for damage.
Not finding anything obvious I double checked the online troubleshooting guides at 41hz.com and realised that by default the amp is muted, you are required to jump two pins to bring it out of mute I tested this with a peice of wire and there was life!
I've now mounted the amp into a case which will also house my steering wheel control interface for the carpc.
Here is a shot of my test setup using my trusty Zune as a source;
So far I'm extremely impressed with the output of this little amp, it stays cool, sounds great.. and its really pretty loud!
Just need to get the rest of the install finished now