Two years or so ago I embarked on building a amplifier.
I never got around to doing a proper write up so here it is! (minus the proper part)
I saw a kit on eBay and read some reviews about the LM3886, all of which were good. Decided this would be my first amplifier project.
As usual I ended up spending far more money than I had intended. It started out partly as a money saving venture, a good quality amp is expensive but DIY is cheap.
Well it's cheap when you know what you're doing.
In the end I was happy, it sounded great and I learned a lot in the process.
I had built a small tube buffer amplifier (another kit from China) which exposed me a bit to transformer/mains voltage, I asked a coworker to give me a hand wiring up the transformer which gave me a bit more confidence dealing with mains voltage.
This project however I did myself and helped increase my comfort with mains - no shocks!
Looking back at this work I am somewhat unhappy about the wiring which is pretty sloppy. I'm pretty sure I covered up the mains connectors, and I'm pretty sure I
connected a chassis ground. I know however I checked for continuity to earth ground.
In the end this amplifier ended up in the hands of my friend. I had purchased another kit to build one for
him, and well it didn't happen and I ended up giving this one away.
This was the kick I needed, my old amplifier (A $2 acquirement at a garage sale - worked great
but came no where close to the great clean sound the LM3886 produced.
I'll eventually get the photos of that new amp I built which I'm much happier build wise with.
One thing I still have not been able to figure out is the volume control.
With a loud input source the pot works great, however
it's difficult to drive the amp to it's limits as from my computer the sound-card clips before the
amp does.
I believe I need a preamp in there and as of 2015-05-29 I have ordered a few other kits to try and fill in this gap.
I highly suggest this amplifier, other than the caps I did not switch out any of the components.
Folks on http://www.diyaudio.com/ have many suggestions for components to swap out.
At some point I may give it a go, but I think my speakers are now the weak link and I have no complaints
about the sound!.
I saw a kit on eBay and read some reviews about the LM3886, all of which were good. Decided this would be my first amplifier project.
As usual I ended up spending far more money than I had intended. It started out partly as a money saving venture, a good quality amp is expensive but DIY is cheap.
Well it's cheap when you know what you're doing.
In the end I was happy, it sounded great and I learned a lot in the process.
I had built a small tube buffer amplifier (another kit from China) which exposed me a bit to transformer/mains voltage, I asked a coworker to give me a hand wiring up the transformer which gave me a bit more confidence dealing with mains voltage.
This project however I did myself and helped increase my comfort with mains - no shocks!
Looking back at this work I am somewhat unhappy about the wiring which is pretty sloppy. I'm pretty sure I covered up the mains connectors, and I'm pretty sure I
connected a chassis ground. I know however I checked for continuity to earth ground.
In the end this amplifier ended up in the hands of my friend. I had purchased another kit to build one for
him, and well it didn't happen and I ended up giving this one away.
This was the kick I needed, my old amplifier (A $2 acquirement at a garage sale - worked great
but came no where close to the great clean sound the LM3886 produced.
I'll eventually get the photos of that new amp I built which I'm much happier build wise with.
One thing I still have not been able to figure out is the volume control.
With a loud input source the pot works great, however
it's difficult to drive the amp to it's limits as from my computer the sound-card clips before the
amp does.
I believe I need a preamp in there and as of 2015-05-29 I have ordered a few other kits to try and fill in this gap.
I highly suggest this amplifier, other than the caps I did not switch out any of the components.
Folks on http://www.diyaudio.com/ have many suggestions for components to swap out.
At some point I may give it a go, but I think my speakers are now the weak link and I have no complaints
about the sound!.
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Transformer
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I bought the transformer from the same eBay seller and s/he had shipped it all together.
So in transit one of the Capacitors was damaged. The seller was happy to replace it but being in a rush to get things underway I ordered some caps from digikey - Nichicon UFW1H103MRD - $8 a pop!
So in transit one of the Capacitors was damaged. The seller was happy to replace it but being in a rush to get things underway I ordered some caps from digikey - Nichicon UFW1H103MRD - $8 a pop!
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| Damaged cap! |
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| Nichicon UFW1H103MRD |
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| Pot, I believe this is a ALPS 100k |
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| Step attenuator I ordered - I never build it |
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| some progress on the amp pcb |
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| bottom of psu pcb |
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| Bottom of the amp pcb |
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| Power-supply PCB almost populated |
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| All done! |
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| Basic test using a scrap heatsink |
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| Messy workbench! |
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| Speaker protection board |
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| The testing setup. |
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| Small device that has some RCA plugs and is wired to the pot. Useful for the testing process |
Getting the heat sinks mounted was a exercise in frustration
Drilling the holes in took way too much effort. If only I had a drill press.
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| I tried to drill the other way, it sorta worked. |
It all worked out in the end.
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| Starting to figure out how to lay everything out |
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| IEC Connector with the integrated fuse holder |
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| Hey not bad! |
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| Starting to wire up everything |
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| The embarrassing layout |
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| Sitting open while I do tests |
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| Close up of the IEC connector, you can see how much of a struggle I had cutting that hole. It wasn't perfect but it's on the back, so hey no one will notice! |
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| close up of the power button |
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| Power button switch |
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| Speaker binding posts installed |
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| All the components laid out on the bottom plate of the chassis |
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| It's a mess in there.... |
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| Back of the amp with stuff connected |
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| Turned on, look at that pretty power glow! |
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| Hey you can see ole reliable still on the shelf! |
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