Thought I would share my first DIY amplifier build.
My goal was to replace my Dayton APA-150 integrated amplifier with a simpler mono amplifier without spending much more than $150. This is the amplifier I use for speaker testing. After some research, I settled on a Sure Electronics AA-AB31316 from Parts Express. It was about $50. It claims to do 400 watts at 1.5 ohms. So should not have any trouble with subwoofer tests (other than 10% THD).
However, at 294 watts, is down to 1%.
Since I have many quality notebook adapters collecting dust, planned to use one of them. After trying a couple was not happy with noise issues and decided to shell out cash for the recommended Meanwell LRS-350-36. So spent another $44, but was happy with the results. Finally needed a case, so went fishing on ebay and found something in a nice aluminum case for $25. So, total was still under what I paid for my APA-150.
After spending a few more bucks for m3 metric bolts to mount the amp, here is the result...
So, a couple of worthwhile notes here. Originally planned to use a right angle rca plug into the amplifier jack. In the end, the only one I found did not fit in the case. So, tried to use some board connections for the input, but they are closer together than I liked, so removed the rca jack (it was just left of the tie wrap) and used its connections to solder a nice rca cable with a male plug on the end. This reduced the number of input splices, so all good. Btw, the tie wrap provides strain relief for the rca cable as it runs on the underside of the board. Note the similar approach for the speaker connection. I used some leftover flat speaker cable I had and terminated with some nice banana plugs. Finally, for safety sake, I ran a ground to the amp post on the underside of the lower left.
I decided the power supply would need to be better integrated, so I velcroed it to the top of the case. Not pretty, but functional as dangerous to leave flopping around haphazardly...
At this point, I put the top half of the case cover on and ran some functional tests. After running for a while, the cooling fan was coming on for short bursts. So decided to ensure I had enough air flow through the case, I got out my dremel and carved a notch out of the bottom of the end panel with the power connectors. It is about 14 mm high - just large enough to allow air flow, but small enough that my fingers would not be able to go in. Just to be sure, plan to add some plastic screen to cover it. After drilling and carving a slot for the power wiring and adding some plastic insulator around it, here is the result:
Since wanted the amp to look a bit cleaner in front, rather than another slot, decided to drill some vent holes. While working on the input connections, found that the amp had provided a standby power switch connector. I scrounged around and found a little single pole toggle and a computer wiring harness with a connector that would mate to the amplifier one. Needed another slot for the input cable and so added it on the side closest to where the input cable runs. The speaker cable fits nicely between the case side and the end panel and is more of a dull edge than if I cut a slot. So the bolts on that side are not torqued as much and added some locktite for good measure. Here is the final result:
My goal was to replace my Dayton APA-150 integrated amplifier with a simpler mono amplifier without spending much more than $150. This is the amplifier I use for speaker testing. After some research, I settled on a Sure Electronics AA-AB31316 from Parts Express. It was about $50. It claims to do 400 watts at 1.5 ohms. So should not have any trouble with subwoofer tests (other than 10% THD).
However, at 294 watts, is down to 1%.Since I have many quality notebook adapters collecting dust, planned to use one of them. After trying a couple was not happy with noise issues and decided to shell out cash for the recommended Meanwell LRS-350-36. So spent another $44, but was happy with the results. Finally needed a case, so went fishing on ebay and found something in a nice aluminum case for $25. So, total was still under what I paid for my APA-150.
After spending a few more bucks for m3 metric bolts to mount the amp, here is the result...
So, a couple of worthwhile notes here. Originally planned to use a right angle rca plug into the amplifier jack. In the end, the only one I found did not fit in the case. So, tried to use some board connections for the input, but they are closer together than I liked, so removed the rca jack (it was just left of the tie wrap) and used its connections to solder a nice rca cable with a male plug on the end. This reduced the number of input splices, so all good. Btw, the tie wrap provides strain relief for the rca cable as it runs on the underside of the board. Note the similar approach for the speaker connection. I used some leftover flat speaker cable I had and terminated with some nice banana plugs. Finally, for safety sake, I ran a ground to the amp post on the underside of the lower left.
I decided the power supply would need to be better integrated, so I velcroed it to the top of the case. Not pretty, but functional as dangerous to leave flopping around haphazardly...
At this point, I put the top half of the case cover on and ran some functional tests. After running for a while, the cooling fan was coming on for short bursts. So decided to ensure I had enough air flow through the case, I got out my dremel and carved a notch out of the bottom of the end panel with the power connectors. It is about 14 mm high - just large enough to allow air flow, but small enough that my fingers would not be able to go in. Just to be sure, plan to add some plastic screen to cover it. After drilling and carving a slot for the power wiring and adding some plastic insulator around it, here is the result:
Since wanted the amp to look a bit cleaner in front, rather than another slot, decided to drill some vent holes. While working on the input connections, found that the amp had provided a standby power switch connector. I scrounged around and found a little single pole toggle and a computer wiring harness with a connector that would mate to the amplifier one. Needed another slot for the input cable and so added it on the side closest to where the input cable runs. The speaker cable fits nicely between the case side and the end panel and is more of a dull edge than if I cut a slot. So the bolts on that side are not torqued as much and added some locktite for good measure. Here is the final result:
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