Hello, that's my first post here!
I've been reading about chip amps, specially LM3886, and I intend to build my own.
I'll drive an 2 ohm equivalent load (speaker in parallel with tweeter, 50W each, 100W total)
I've followed the LM3886's datasheet and some DIY from here and the web and came up with this design:
I uploaded the image at TinyPic, in case attachment isn't good enough.
I really appreciate if you guys tell me what you think about the design. Please give me your opinion!
I've been reading about chip amps, specially LM3886, and I intend to build my own.
I'll drive an 2 ohm equivalent load (speaker in parallel with tweeter, 50W each, 100W total)
I've followed the LM3886's datasheet and some DIY from here and the web and came up with this design:
I uploaded the image at TinyPic, in case attachment isn't good enough.
An externally hosted image should be here but it was not working when we last tested it.
I really appreciate if you guys tell me what you think about the design. Please give me your opinion!
Skip the adjustable gain, and use 0.1% resistors in the feedback loop.
Insert swamping resistors in series with the output of each chip. Put a trap on the input and a snubber on the output.
Parallel chip amps don't always work as well in real life as they do on paper. Precision feedback network and swamping resistors on the output are an absolute must.
Insert swamping resistors in series with the output of each chip. Put a trap on the input and a snubber on the output.
Parallel chip amps don't always work as well in real life as they do on paper. Precision feedback network and swamping resistors on the output are an absolute must.
For a first chipamp stick with a single chip with provision for all the optional components.
use input filters at the input of the power amp and at the input if there is a pre-amp.
The buffer on your input is in the wrong place.
The volume control can benefit from the buffer.
The interconnect cables cannot benefit from a buffer.
use input filters at the input of the power amp and at the input if there is a pre-amp.
The buffer on your input is in the wrong place.
The volume control can benefit from the buffer.
The interconnect cables cannot benefit from a buffer.
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0.1% resistors are really hard to find here in Brazil...
I thought of using multi-turn pots to set the gain according to my input
Andrew, when you said "single chip" you mean one LM3886 to each speaker? So each will drive a 4 ohm load/50W (a speaker or tweeter) separately?
I'm an undergraduate at Electrical Engineering and i'm taking classes about analog circuits this semester, but I'm not a dedicated student actually...
I thought of using multi-turn pots to set the gain according to my input
Andrew, when you said "single chip" you mean one LM3886 to each speaker? So each will drive a 4 ohm load/50W (a speaker or tweeter) separately?
What are these? What they do?
I'm an undergraduate at Electrical Engineering and i'm taking classes about analog circuits this semester, but I'm not a dedicated student actually...
Thanks, Eddie!
I can import them, but it will be ridiculously expensive! hahahaha
Better buy a bunch of 1% and hand match them.
I intend to use my PC as audio source, so I have to measure the voltage from my audio signal to set the gain correctly, right?
These swamping resistors are really small, like 0,1ohm? Texas uses 0.1ohm/1%/3W? Is that good for me too?
I thought of using one chip to each speaker, but I think only 2 wires for each bookshelf speaker will be better, so I decided to parallel them
I'll make this changes in my project and send a new picture to you, guys!
Thanks a lot!
I can import them, but it will be ridiculously expensive! hahahaha
Better buy a bunch of 1% and hand match them.
I intend to use my PC as audio source, so I have to measure the voltage from my audio signal to set the gain correctly, right?
These swamping resistors are really small, like 0,1ohm? Texas uses 0.1ohm/1%/3W? Is that good for me too?
I thought of using one chip to each speaker, but I think only 2 wires for each bookshelf speaker will be better, so I decided to parallel them
I'll make this changes in my project and send a new picture to you, guys!
Thanks a lot!
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That's a shame, but you can hand match some resistors.
No! 0.5-2 ohms is sufficient.
Considering the caliber of your questions, I would recommend against trying a parallel amp. Things go wrong and if you don't understand what's going on you're not going to be successful. Please get a simple chip amp up and running first.
Read and understand this before you plan your layout. Proper grounding make or break any audio project. Grounding Principles - The Signal - Archives - TI E2E Community Read some of the other articles too. You say that resistors are expensive but here's a heaping helping of valuable information, for free.
I'm really a newbie at this amplifier thing! Hahahaha
I think I'll follow your advice, build a single chip first and test it on my speakers.
The price of the resistors are not the problem...the taxes here are!
Maybe in the future I make this investment on my amp, but for now, something that works is fine.
Thanks for the article, I'll read them all!
I think I'll follow your advice, build a single chip first and test it on my speakers.
The price of the resistors are not the problem...the taxes here are!
Maybe in the future I make this investment on my amp, but for now, something that works is fine.
Thanks for the article, I'll read them all!
Shipping to Brazil is expensive...about 30 US$ via courier delivery and the taxes are almost 100% of the cost including shipping. Postal services like USPS aren't normally taxed here if the size is not too big.
2 weeks ago I bought 600 resistors for 5$ including shipping from China! I'm sure they're not like Vishay's but will work for my first amps!
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