Discrete audio amplifier project PT21 project completion 

That’s one of the best series on RU-vid if you want to learn about solid state amplifier circuits!! Thank you for walking us through all those details and steps, I learned a ton! Your an amazing teacher . Thanks

A huge thank you to from this olde guy who dabbles in electronics down here in New Zealand!. Really enjoyed the ride as i experienced the actual process from design to working amplifier (my hat's off to you for having so much knowledge & skill). Oh... and give The Snickers a treat to celebrate the the 501's completion & a chin scratch on behalf of myself... another 'techie' who likes cats!

you made a good introduction to making amplifiers, I followed from the beginning :)) greetings from Croatia

@2:44, Snicker's thinking " What is my human doing ? Very Interesting ! "

Great project ! It's been very educational following along. Always enjoy your videos. You give easy to follow explanations (narration) with enough detail to understand without over complicating things. Thanks from Canada.

Fantastic project! I learned so much from this project. It’s been an amazing journey. At some point I will make a PCB for this project. When I do, I will be sure to share it with you. Hopefully then you’ll correct my mistakes. Thanks again for this project. Those who can, do. Those who can’t, teach. You belie this entirely. Greetings from the UK.

So interesting to follow! I have tired and failed a few times with these types of projects but would love to give this a try once you have boards made up. Thanks for taking the time John.

Thank you 4 sharing this whole process. It has been one of the best learning processes I have been through for years. Thank you.

Congrats on finishing this long project. It's unique on RU-vid and I think quite a valuable resource for people. You have too many amps. Maybe you should build something that needs an amp next? How about a "busker's box" battery powered mini PA for street musicians? I think you should use your discreet amplifier as your main computer amp, too. I couldn't believe it when you tossed it on the pile... You did a great job, though. Thanks for making vids your own way.

Nice Work Buddy I'm Impressed These Would Power Some Nice Studio Monitors

Awesome work and you're really great to watch! Thanks for taking us along for the process, keep up the great work because it's inspiring for many of us new guys!

Great work John and congratulations at the finish line!

Thanks, John, it's been a great following along.

The amplifier sure looks good.

Very nice work John!!

Hey John, Good job as usual. It's been a great series, always learn a lot. Thank you for sharing your knowledge. Happy Year End, all the best from Oregon, C.

good job john. i learned alot from you. thanks. pcb design and manufacturing would be nice to see in future.

Thank you for all the work you put into this and for the share of schematic and parts list as it looks to be a very nice amp, would have been interested in a couple of boards but think shipping to UK would be rather expensive so will have to look into putting my own board together from you very helpful information.

Hey John, I'm really happy to have found your channel! I'm teaching myself audio electronics and your work is great for that, especially this project! I'm slowly going through your videos and enjoying every minute. Would be very interesting to follow the process of creating the board layout as well. I know this process might be messy with lots of mistakes that get eventually ironed out, and I think that mistakes and the discussion around them have more educational value than the final result.

Well done John 👍 I would like this for my guitar amp build 🤔

Congratulations 👍

At last it's done. Bravo. It's a sexy looking schematic.

Howdy. I admire your persistence and stamina. Regards.

I am definitely up to make this amplifier!!! It's a great work!

Great job

Hi. Thank you for the really interesting series on this amp. Can you clarify the process for setting the bias using a multimeter?

Enjoyed watching this series, John. I have a pile of old MusicMan guitar amplifier power transformers that might be a good fit for this circuit, so I might build a set of mono blocks out of this for kicks. (All of my amp builds are generally with valves, but I'm not afraid to use sand in those projects, so what the heck, branch out a bit!)

Muy bueno tu proyecto. Saludos desde argentina

Great! I was expecting this to arrive one of these days. It was very interesting following this development. I surely want to build the amp. I will feed it perfect DC with my stash of about 300 perfect Li-ion cells for which I have no other use for the time being. So, a large battery pack in the range of 32-36 VDC will do nicely with amphours a galore. The pre-made board would be welcome.

John, put me down for a few bare boards if you decide to have them done. I will gladly pay in advance.

hey john, can you share the file for the simulation, i'd like to fiddle around with it, thanks :), btw well done i've been following along this series, now finally i can create my own layout for this amplifier and listen it on my own

Awesome

Yes, I want to build this amp. Could you talk about adding more power transistors ? Also, what about 1. using your o-scope to sum input and output out of phase for null to display output distortion ? 2. using opamp in place of o-scope to display output distortion ?

....great selection of components , john . . Should be Very quiet front-end . . . .....shalom,a.j.

Whoooo Hooooooo,,, Right on John,, way to go,, Can you provide a source of proper power transformers for us.. ?

such a long journey

501 amp like the jeans. Is it truly that good? Maybe sitting in 501 jeans while getting a JAT501 full body message.

You shown amplifier testing videos feeding 1 Khz signal as input but will we get the same output power from an audio chip when playing music/songs (having various frequency bands) from phone ?

Can make some sound test demo with song sir for know how sound this amp

Where did you get this heatsink - it's huge. For the amp load simulations I actually use something very much like, say 2way spkr with crossover. The spkr drivers simulate quite similar to real drivers. One thing - depending on the crossover the actual impedance for 4 ohm drivers may drop as low as 2 ohm plus +/-60 degrees phase shift - not an easy load. When simulating with simple resistors as load I usually add capacitor in parallel, starting with 1nF and increasing until 1uF and watching for oscillations. But that's just simulations, things are most likely more complex in real life.

Hi john, can you share the file for the simulation, thank you, great project :D

Yes premade boards

Also wanted to add,, IF the boards are going to be limited quantity ,, maybe an JohnAudioTech Fan could do boards up for the rest of us? WhattyaThink??? :)

Pre-made boards please! Maybe 2 channels on one board... Just an idea

What about pcb layout and performance testing with that? Possibly send to amir from audiosciencereview to measure it fully?

Thanks, appreciated. Where Can We Get TRANSFORMERS? I searched for them about a year ago, and, basically could find almost nothing! Please link to 100va and 200va center taped transformer sources. When I was a kid, getting into electronics, every supply house had any transformer you could imagine, if not in stock, they got it quick. What happened from then to now? Maybe I forgot how to search for stuff a year ago?

Why changed to darlington transistors

You've got lots of SI multipler/unit case mistakes in the BOM I'm afraid. Case matters for SI symbols. H = henry, F = farad, K = kelvin, V = volt, k = kilo, f = femto, h = hecto, v isnt an SI thing I believe - sometimes these distinctions are crucial, confusing milli (m) for mega (M) for instance. All unit names like henry and ohm are not capitalized, the people they are named after are capitalized as in Ohm's law (only exception is "degrees Celcius", for obscure reasons). Be consoled by the fact you are not alone in this, but please fix it :) And of course great to see it complete and wrapped up - looking good!

Then, let's move to other topics. Cheers from Indonesia

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I will probably build your amp for my car audio system! That is unless I can find a good class D design for DIY that has the same output power/THD parameters as this one. I am going to include external protection circuit for sure, though.

I built this amp. It works but I'm only getting around 6V across my 4ohm sub at max volume ( max volume isn't as loud either) at +-36V...any suggestions as to why

Bro i would like to send u some pictures of a class A audio amplifier .. its 45w rms ahuja (indian brand with very good reputation of quality products) the amplifier circuit quality is really good , like the builders have taken care of it while making & its like 70$ for 45w .. now the amplifier whan warms up makes some noise like pak pak pak... Would be happy if u help me .

Sign me up for a circuit board!

Hello, John: The Link you posted for boards (BLUE) by 576PINOY_TECH has a board that has a schematic that is not the same as yours Q1 thru Q4 are wrong also no C2 his schematic is the same as his boards I have some I can send you 1 just need an address I remember you said you were dumping your PO Box let me know if you want one.

How to set quecent current of this amplifier??

Care to share the LTspice files?

hi John is this capacitor characteristic relevant to hi-fi ? ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-2287hcWFqe8.html

so, you aren't going to make a kit with board! disappointing!