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Picture of Make your first Serious Amplifier
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I did it! I've always wanted to build my own amplifier, and now, finally, I made one. It's my first "serious audio" project ever.

Starting this project was daunting to me. There was a gap between buying the parts and actually making the amplifier... a two year gap, as a matter of fact. I know a thing or two about analog electronics and I can read and understand electronic diagrams, but I never made something from scratch that connects directly to a wall outlet. And I usually make stuff with electronics either for kids or as a "proof of concept", where accuracy and details matter only little. In other words, I was just insecure about me as a maker of Serious Amplifiers.

What helped me to get started is that I just needed an amplifier. I love to play music and the best sound system I had was my iMac. And that proved not good enough for me. So I had the choice between buying a cheap receiver while knowing I had all the parts for a much better amp or just get started building it. Oh boy, I am SO glad I did just that!

If you find yourself dreaming about building an amplifier now and then, but are not sure about how to get it done: Read on! I described the making of my Serious Amp as good as possible, including the mistakes and successes. The result is not a Perfect Amp, but it surely is a Serious One that is not that hard to build even if you never built one before.

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If you like this project, please vote for it in the contests. Thanks!
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This amplifier is the best one I've ever owned (that claim isn't worth very much) and I'm really, really happy with it. Even with my secondhand (€10,-) loudspeakers it sounds pretty nice. In the video, the sound is recorded with the on-camera mic. What you hear is far, far away from the real life experience.

The amp is a so called Gainclone, using one LM3886 op-amp per channel. The power supply is based on a (way too large) 230VA toroid transformer. It took me about 32 hours to build the amp and power supply.

In this Instructable, I'll describe how I made the power supply and amplifier. More important, I'll also describe what I would do different if I had to do the project again.
 
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mfaust made it!5 months ago

Thank you again for this great instructable. I've finished my first gainclone this weekend and can't count the hours I've stared on this page. Also, thank you again for your help. I forgot to ground the secondary coil during my first attempt which (according to a friend) causes a "floating" of the current. However, it finally works perfectly fine, without any noise. I've attached two pictures, the wiring is not as nice as yours, but works for me :)

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ynze (author)  mfaust5 months ago

Wow! Thanks so much for your pics and nice comment! Your amp looks GREAT, thumbs up! You added a second line-in, didn't you?

Cheers, Y.

mfaust ynze5 months ago

Yes, it's a second input. I am using the amp for CDs and PC and since I already had the parts I thought it's more convenient.

Faulty LED5 months ago

Could you give us some computer generated schematics? I find them easier to read. Eagle is a good program.

pmk2228 months ago

this is a great instructable, very easy to follow. i have always wanted to own an amp that worked well, but not having a lot of money or knowledge i figured building one would be the best but never found a good, easy to follow guide. i will definitely be using this to build one for my next serious project.

aalejo pmk2228 months ago

ok if of you have a problem with that my i suggest!!!!!!!!!!! lm386 half watt ic!!!! i try that one man makes satisfie you self if you the 386 one

aalejo aalejo8 months ago

and less cheaper than to make and too powerfull and smokey !!!! you will love it

pmk222 aalejo8 months ago

i will research the usage of this, if i can figure it out i may use this idea, thanks!

aalejo pmk2228 months ago

ill give a schematic in the breadboard i wanna make this!!! and work !!! there was a secret about my schematic that make distortion clear !!! figure it out !!!! so it will help you for first speaker and!!!! by the way!!!!!! there have some missing connection for it and is the!!!!......... hahaha figure it out!!!!. so it will may get you been un the challege!!!

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aalejo pmk2228 months ago

your welcome!!! :D

Dunluce8 months ago

Enjoyed your project and its inspired me to try to build one. My knowledge of electronics is quite limited but I have been reading up a bit on some of the sites you suggested. One question, where do you connect in your switch, LED and resistor? I don't see them in any of your schematics.

mfaust8 months ago

Awesome work! I read the article about your amp on hackaday.com and I've never heard about gainclones before. I haven't such a deep knowledge about electronics, but thought I give it a try. So I ordered all parts the next day (but skipped the Anti-interference module and the rectifier). I ordered the same toroid transformer from Conrad (Germany) and followed your instructions about the second coil, connected the red and purple wire and soldered them on the ground connector of the 220V power cable. I'm pretty sure that I've soldered everything else correctly and triple checked each connection. But after I powered it, the clamp that connected the second coil to the ground started smoking and the speaker made strange sounds!! I've no idea what I've done wrong here, so I can only guess:
Was it wrong to connect the secondary coils to the ground?

I connected every ground of the sketch (amp+power supply) to the ground of the 220V input, is that correct?

I forgot to wire the parallel capacitors (100uF and 0,1uF) on the V+ cable, but I don't think that was the problem and now I'm scared to retry without any changes.

I used a cheap 4Ohm instead of a 8Ohm speaker, just in case I break it.

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ynze (author)  mfaust8 months ago

Hi mfaust,

Thanks for the post. You obviously created a short somewhere, but I can't tell why and where... My guess is that you connected the secondary coils the wrong way.

Try this:

  • Take out the toroid transformer.
  • Compare your toroid's label with mine (enclosed image). With my model, the first sec. coil has colors Black - Red (SW-RT on the label). The other sec. coil has colors Purple and White (VIO-WS on the label). Is that the same as with your model?
  • If so: Disconnect the purple and red wires.
  • Connect just the transformer's primary coil to 230 Volts (nothing can go wrong now, as long as you make sure that the secondary coils' wires don't touch anything). With a Voltmeter, measure the Voltage between the secondary coils' wires: So measure between red and white, red and purple, red and black, etc.
  • Between two pairs of wires you should read 18 Volts AC.
  • Write down what the positive and minus leads are of each coil (you can use the Voltmeter for that. Hook up the black probe to the Voltmeter's COM. If you read +18 Volts, the black probe is connected to the coil's minus lead.

If you did this, please leave a comment with the results. We'll go from there :-)

Good luck!

Y.

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mfaust ynze8 months ago

Hello ynze,

I checked the toroid's model number, it's exactly the same you used. I measured the output AC current I on the black and white wires I connected the power supply with and got the 18 Volts. I also have the 25V output you mentioned in your instruction. So I thinks this works fine.

Anyway, thanks for your help! I just have to confess that my knowledge is not sufficent for bugfixing this circuit, so I will ask some friends for help. I let you know if I get this thing running some day ;)

mfaust ynze8 months ago

Thank you very much for the reply! It's the first thing I'm gonna try tomorrow!

maxatan9 months ago

Very cool project ! Congratulations !

You say it is a serious amplifier and it cost you about 100$.

Do you think you can build other serious amplifier but cheaper ?

Best regards

bullzebub9 months ago

Nice! i didnt know about these! a gainclone would solve much of what ive been looking for.

questions: do you think i could use a computer PSU as the power source?

also i dont really need a volume control (i could do that on the computer) ... you think replacing the pot with a fixed resistor would solve the problem with noise?

ynze (author)  bullzebub9 months ago

I'm not sure about the power supply from a PC. It might work. According to the LM3886 datasheet (http://www.ti.com/lit/ds/symlink/lm3886.pdf) you need at least 20 Volt voltage supply (|-V| + |+V|). If you can find -12V and +12V connections in a PC's power supply the opamp will work, but the power output will be far less than 60 Watts.

Yes, you can replace the pot with a fixed resistor. I haven't tried this, but I so no reason why it shouldn't work.

There is a third connection technique, called wire wrapping. You use a board that looks somewhat like a PCB but has no conductive material on it. It has rows of holes. You push the pins through and use a special tool to wrap wire tightly around the pin. You would need to be creative when it comes to the high current portions because the wire is only signal strength capable, but that is most of the wiring.
ynze (author)  mid_life_crisis9 months ago

Thanks for this! I looked it up and really like it, although I'm not sure if I can use it for a project like this. To be continued...

Agregory4139 months ago
Overall how much do you think you spent?
ynze (author)  Agregory4139 months ago

In the text I mention around €100,-, but I did this on a small budget. You can easily spend twice the money just on connectors and the potentiometer...

stevenarango9 months ago

Wow that looks great i may give this a go....

i will follow your pictures reading schematics is not my forte. but i will try it...

well done mate.

ynze (author)  stevenarango9 months ago

Thanks! Happy making :-)

sl0j0n9 months ago

Hello, all.

This is pretty cool; haven't seen anything like it since I was young.
[Nearly 60 now.]
I've got some nice speakers from a home theater system that died,
& I like to build something to drive them with,
but its been decades since I played w/ 'hobby' electronics.
Have a GREAT day, neighbors!

nerd74739 months ago
nice work dude
gluvit9 months ago
Cool
zack_man8889 months ago
For what it's worth, I would take a point-to-point hand-wired amp over a PCB any day. It just has that vintage coolness factor. If you can get really good at point-to-point, I would recommend you keep trying it, unless you are really dead-set on using a PCB.
ynze (author)  zack_man8889 months ago
Thanks for mentioning this! I didn't mention it in the steps, but I also really like the point-to-point look. I've read about it, and another reason to do it seems that it keeps the paths as short as possible. So no, I'm not set on using pcb's next time if I find a good way to keep the wiring proper.
This looks like a Very nice project! It's Clean, Useful and Practical. I LOVE how you're using the pudy to hold parts to be soldered! I'd never thought of that before. VERY well done ;)
ynze (author)  your_dragon1139 months ago
Thanks :-)
Uranio239 months ago
Looks really cool. I made a single channel amp with speakers just for fun some time ago with recycled parts from and old radio and the box was made out of ... box, shoe box and sounded good enough for a laptop or cellphone. I remember using an old gameboy advance 12V-500mA power supply.

You should definitely rewire everything again on PCB. You can use PCB plates with holes already made and coper lines arranged like a prototype board so you don't have to make the whole thing. Just place components and solder them.

I think your case is super great, I like a lot how it looks and I'm felling in the mood of making some speakers for my brother's tablet :P

PD: The noise you hear could be because you are soldering everything p2p, using PCB should get rid of the noise.
aelias369 months ago
I'd avoid using XLR plugs for connecting the power supply to the amplifier. It's generally used for audio signals, not power, in the professional audio world.
ac-dc aelias369 months ago
Not really relevant what other common use it has so long as it is labeled appropriately if the amp is ever sold or given away. XLR is a nice, robust power supply connector for those who insist on having a separate tethered power supply... which doesn't really make any sense at all if the two will forever be used together but some people do it that way regardless.

It would make more sense if it were a E-core transformer since those have higher magnetic field strength escaping to pollute the low level audio signals but even then one can just add a Mu-metal shield if they deem it worthwhile. Most consumer amp manufacturers don't feel that it is worthwhile.
ynze (author)  ac-dc9 months ago
The reason for me to make a separate PS was my hunch that my maiden amp wouldn't be perfect, so I might want to make another one someday.

Thnx for the useful comments!
ynze (author)  aelias369 months ago
A friend of mine told me something similar. XLR plugs are used for connecting mic's, right? I got the idea from Mark Hennesy's website: http://www.mhennessy.f9.co.uk/microamp/construction.htm.
ac-dc ynze9 months ago
XLR is the old school mic and connector plug because it is very sturdy, which is useful in professional environments where it may be subject to rough treatment or frequent connections and disconnections. That sturdiness also means it is capable of far more current than you'd ever need for a microphone. Connectors used to be designed RIGHT, now a days newer connectors are just designed to be tiny and cheap, on disposable electronics.
Yes, mics among other things. Worst-case is you (or someone else) would accidentally plug your power supply into an XLR socket on something that was expecting mic-level inputs, and you'd destroy that piece of equipment. Much better to use a less common connector.
I was thinking the same thing but the variety of XLR he is using is rated for 5 Amps.(according to the link in the 'ible) http://www.conrad.nl/ce/nl/product/715710/Rean-AV-RT3MPR-XLR-connector-Stekker-inbouw-verticaal-Aantal-polen-3Zilver-1-stuks?ref=list
Knightsabre9 months ago
Nice project! FWIW, you can prevent drill-through breakouts by placing a sacrificial piece on the face of the piece you want drilled. Clamp a piece of scrap material on the face that you want facing out. The compression will keep the force of the drill bit from pushing the newly cut fibers out at the edges, giving you a nice clean hole.
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