Just got the new amp. It is much smaller than I expected:
I'm not a big fan of the semi-proprietary connector - I'm sure it's some sort of 8x1 JST connector, but it's pretty fragile-looking, so I'd want readily-available replacements if something broke. Also, the mounting holes are smaller than standard computer standoff size - standoffs are 32, the holes on this one are probably about 40. I'm not sure if I'll be expanding them with a file, since they are pretty close to some electrical parts. I've been using motherboard standoffs throughout this project and having to go size down is a pain.
Heatsink-wise, I'd say this thing is definitely lacking. First of all, the heatsink on seller's page is much longer - i think it's actually 2 of them put together. The heatsink also doesn't cover the whole chip - it's too thin. I'll go to Radioshack tomorrow and pickup something a bit more decent. Lastly, the thermal paste is a paste, not an adhesive, as far as I can tell. I'm not sure how you are supposed to mount the provided heatsink with this paste - I'm just gonna use my thermal epoxy.
On the plus side - I soldered the headphone jacks onto the wires, attached the speaker harness and fired it up without the heatsink. I remember that the last amp (same chip), I tried doing that and it didn't get that warm that quickly. This one did the same - I only played music for about 10-20 seconds, pretty quietly, just to make sure it works. It does indeed work. I can't tell how good the quality is since my test speakers are absolute crap. During that 20 second test, the chip barely got warm, which is a good sign. A medium sized heatsink should do the job just fine.
Epoxied a heatsink to the chip, trimmer the speaker wires:
Overall it sounds pretty nice. There was absolutely no pop when I turned it on.
I bought smaller standoffs in Radioshack for 2.99 a 4pack. The standoffs are female on both ends, which is nice - a 40 nut would not have fit on that board. Now, onto installing this thing into the case!
Very good job ! I like that !
@nivanov, I know the main reason why you got the new amp was because of your limited space. If you take that out of the equation, which amp would you recommend?
If space isn't an issue, I think I'd go with a standard external automotive amplifier :)
@nivanov, sorry, my bad... I mean, which would you recommend between the two you used with your project?
I'd go with TDA7850 with Denoiser - it's $25 and has all the features I need. It's also much smaller than amp9 and less than 1/3 of the price for the preassembled unit. The other TDA7850 is pretty good as well, but with my design, I had to relocate the RCA inputs, and, with GLIs, it was just too bulky.
Lastly, Amp9 is a very decent unit, on what seems to be a slightly better chip. However, it's never in stock assembled, costs about 3x the price of TDA7850, uses 4x2 header connector which isn't available retail and not supplied with the amp itself, and the biggest unit, to boot.
EDIT: just checked 41hz: AMP9-BASIC Assembled is back in stock. 84 plus shipping. I think it's about $92 total to get it shipped to US, so I'd definitely at least give the TDA7850 w/ Denoiser a try
To prevent thump and control the amplifier from Windows, I purchased this (if the link is dead, search Ebay for "USB Relay Controller - RS232 Serial controlled board"). It's pretty much exactly what I was going to build myself, only in a neater package. It has a usb-controlled relay which can handle up to 15A at 12V - more than enough for me. Hopefully, this is the last part!
I thought these amps are 4X50W?? Doesn't that mean 200W total, therefore needing 15A or 20A? Sorry still a newb on automotive electronics.
Originally Posted by nivanov
Also whats the advantage of this USB Relay controller? Couldn't you tap into a switched fuse from the fuse box?
As far as amplifier power draw goes, I wasn't that sure either. I've searched the boards and the most common approximation is to divide total audio power output by 10. It's a rough approximation, but I don't really need to know the exact number. With my setup (powering from the harness) I can afford a 50W power draw, which should be plenty.
Originally Posted by audballz
As far as the relay goes, I wanted an ability to turn the amp on and off from Windows - this relay lets me do exactly that. This would prevent turn-on pop as well as random noise my sound card makes before it gets initialized.