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Old 13th June 2013, 11:55 AM   #1
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Default Simplest class D amplifier

I am new to building amps so go slow but I do know most of the basics about electronic circuitry

What I want to do is build a class d amplifier for my first amp and I know a class d is fairly complex and isn't something a first time DIY amp builder should start with but I don't really want to build anything less than a class d

I want to build an amp using a 9Vdc psu if possible but I could go with 30vdc or more as well but I would prefer 9vdc
Speakers I would like 4 ohm speakers but any will do as long as the sound is loud and clear and I will get the speakers to Mach but I do have 2 150w 4ohm car speakers laying around but I don't need to use them in this project
I would like between 50 to 360w 1 or 2 Chanel amp easiest is better I don't mind using a chip but any other way would be preferable but easiest is better
I would like to spend less than $50 not including psu and PCB boards
When I say easiest I mean less complex but I also mean what would sound the best without being to complex or going over $50 I don't mind going a little over budget
I would like an amp that I could combine in series or parallel withe another one or more the same to increase the sound output
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Old 13th June 2013, 12:12 PM   #2
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Take a mosfet gate driver ic like the TC4422/UC3710, add a comparator ic and then make a UcD selfosc topology around that, its limited to max 20V but if you use two per channel in a BTL config, u get twice the power for the same psu voltage.
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Old 13th June 2013, 12:21 PM   #3
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Tekko. like I said I'm fairly new at amp building but what I should have said is I'm fairly new at electronics full stop could you post a link to an example of what you are saying above or explain in detail please because I am a major noob.
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Old 13th June 2013, 01:12 PM   #4
Mihkus is offline Mihkus  Estonia
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I would go for TDA8920TH 50W per channel.
Its pretty simple but ou have to make PCB by yourself...
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Old 13th June 2013, 01:19 PM   #5
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But it takes a pro at smd soldering to solder it, nothing for a beginner.
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Old 13th June 2013, 01:29 PM   #6
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Quote:
Originally Posted by Trexbreath View Post
Tekko. like I said I'm fairly new at amp building but what I should have said is I'm fairly new at electronics full stop could you post a link to an example of what you are saying above or explain in detail please because I am a major noob.
I'm sorry to say this, if you at "level zero" in electronics then you should not get involved yet with class-d, there is no such thing as a simple class d amplifier no matter what people here tell you. class d is collection high speed electronics design disciplines that requires a fairly solid elementary level to deep understanding
of theory and practical knowledge. have you every designed a buck convertor ? heard of frequency compensation ? designed a high speed circuit on a PCB ? Own a oscilloscope (100Mhz at least) ?

Its a tough task near impossible task to jump into.. however.

If can, buy a pre-made design with PCB and get your small toe wet.
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Old 13th June 2013, 01:46 PM   #7
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I got stung a bit when I started in class d.
My attempts at a irs2092 based circuit failed badly.
I found I had to keep tracks as short as possible.
Decoupling close to IC and mosfets was vital.

Even then the 2092 wouldn't give me full power without resetting itself.
I had to scale the over current circuit to stop it resetting quite heavily.
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Old 13th June 2013, 02:03 PM   #8
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Yea I know a class d amp is very complicated but I would have liked to give it a go
If everyone recommends I start easier then I could give a class c amp a go
Answer to questions
No I have not heard of a buck converter and I googled it and could make little sense out of it except that its a dc/dc step down
Frequency compensation I googled this as well and what I got is that networks of resisters and condensers are created to reduce positive feedback but I understood little else
As for high speed circuit do you mean something like a multivibrater occilater using a 555 timer I googled high speed circuit and got something about the gsm network
I have a frequency counter but I am unshore as to wether it works correctly or not but I don't have an occilascop although I am trying to get one
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Old 13th June 2013, 02:22 PM   #9
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Quote:
Originally Posted by nigelwright7557 View Post
I got stung a bit when I started in class d.
My attempts at a irs2092 based circuit failed badly.
I found I had to keep tracks as short as possible.
Decoupling close to IC and mosfets was vital.

Even then the 2092 wouldn't give me full power without resetting itself.
I had to scale the over current circuit to stop it resetting quite heavily.
I'm busing designing version 2 (PCB SMT design) of my inductance test fixture the current one (on veroboard) is working very good vie already confirmed the Arnold cores for my class d amplifier seems to be able to withstand 10-AMPS easily with very good linear current ramps (and reset ones) inductance and saturation currents are now exclusively examined using my storage scope 100Mhz scope.

Anyway the point is ive already learned quite alot working with experimentation circuits like these to confidently build a working and reliable amplifier using a 2092 with local buffers all SMD with CAD modeled resonance.

The reason why you are were probably getting over current reseting is probably lack of di/dt taming which can result in false spikes if im not mistaken the 2092 uses the RDSon of the mosfet to sample overcurrent.
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Old 13th June 2013, 02:35 PM   #10
paskal9 is offline paskal9  Malaysia
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Quote:
Originally Posted by Trexbreath View Post
Yea I know a class d amp is very complicated but I would have liked to give it a go
If everyone recommends I start easier then I could give a class c amp a go
Answer to questions
No I have not heard of a buck converter and I googled it and could make little sense out of it except that its a dc/dc step down
Frequency compensation I googled this as well and what I got is that networks of resisters and condensers are created to reduce positive feedback but I understood little else
As for high speed circuit do you mean something like a multivibrater occilater using a 555 timer I googled high speed circuit and got something about the gsm network
I have a frequency counter but I am unshore as to wether it works correctly or not but I don't have an occilascop although I am trying to get one
well class d isn't exactly complicated, it's just complicated to make work.

if you never built an audio amp before, by all means, avoid starting your journey with class d. skip the scope and dump the money on getting yourself a good soldering iron, components, and better equipment. you don't really need the scope for linear amps.

if you only require a fast track to an actual working amp, then just buy any class d module available cheaply in ebay, parts-express, aliexpress, etc. that'll save you lots of money (and headache) in the process.

but yeah, where's the fun in that..
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