JAT501 amplifier first board test

[@fredfabris7187]

I too have followed this series from the start. It is one of the best solid state electronic series on KZbin. Thanks for all your hard work!

[@kernalkorn1514]

That's a nice, neat layout! That hasn't gone unnoticed man!

[@xanderguldie]

So when are you going to make a website to sell all of these boards you make? I'm guessing lots of people would be interested

[@rogerclass9923]

I'm also very interested in a pair!

[@seanmcguire6998]

Interested in a couple of boards myself

[@law-ofohms7815]

Yes please!

[@TheWillBes]

I’m interested too!

[@AnilKumar-zp2sh]

i also want one, preferably diy parts kit

[@MichaelBeeny]

The slight LF roll off may have been due to your scope being AC coupled at the time of the tests.

[@johnsonlam]

Someone nearby should sent one "old gaming machine" to John.

[@blurpy1]

Hi John, would love to see a video about that attenuation box you made!

[@watup110875]

As always keep up the good work John, helping us brain-dead to learn on each show

[@LGCHILI]

Hi, I've been following this project from its infancy to this stage. I have learned a lot from it, a lot. You're doing a great job John. Please keep it up. I was just of the thought that maybe the final board could be tweaked a little bit to allow the final stage transistors to be on the same side, this would allow to have the heat sink to be on one side and it would eventually save some space in an enclosure or a project box. Just a thought. Looking forward to rev2.

[@jstro-hobbytech]

Hey brother I sent you a patreon message if you don't mind taking a minute to answer it. I'm new to the audio side of electronics. No rush answering. Just wanted to show appreciation for your work.

[@andymouse]

Great to see its working ! I have a design of my own but cant afford to make boards just yet but would love to show you one day, cant wait to see REV2, thanks for your work....cheers.

[@1pcfred]

Seems like a good little 100 W amp to me. Tweaking a board layout is an iterative process. I know it takes me a lot of tries to get something close to optimized. Let's all press F in the chat for PCs 2020. It'll be a few years before I can think of building a new system here.

[@Swodie_Jeetin]

Are you going to sell these? Patreon rewards? You have my attention!

[@gamiwv]

Nice amplifier Not exotic components, not obsolete components. I'm waiting for the pcb final version to buy a pair. Thanks

[@johnsonlam]

May the input capacitor can stay and let a jumper or switch to bypass, good for trouble shooting.

[@JasonLeaman]

Looking Good John, I think your board could be optimized to help clean up that 2k harmonic and perhaps easier layout would help with mounting parts.

[@JohnAudioTech]

The 2K harmonic is from the computer. Distortion from the board is too low to be displayed from this computer's input.

[@sivaprakashmuruganandam5898]

Can pls explain Dolby decoder, it would help me build my project

[@CraftAero]

Google is your friend.

[@fullerjoseph12]

John hey man I've been a subscriber for several months and very much enjoy and think your videos are very useful. With that being said, do you have a suggestion for 24 volts of compact portable power. The 21v boards from parts express just are giving me fits and I'm looking for something else. Thanks in advance

[@JohnAudioTech]

Thanks for watching my videos! Just to be clear, are you looking for a portable power supply?

[@ronniepirtlejr2606]

I am still in the first 5 minutes of video but, could the humming be from your black and red wires running through your preamp, acting as an antenna for your Wi-Fi?

[@MarkTillotson]

That 0.017% harmonic distortion is likely mainly from the layout gaffe with the output inductor closely coupled to one of the emitter resistors (which is clearly wirewound). The power traces under the low level parts of the amp are also potential causes for this. Try replacing the emitter resistors with metal oxide versions perhaps?

[@JohnAudioTech]

Perhaps, but I was getting .005% with the prototype board at both 8 and 4 ohms on my old computer. This was the baseline of what I got measuring the preamp alone on my old computer (limits of my ability to test). The new board has a location for the coil so it doesn't need to be wound on the resistor.

[@pliedtka]

I found all my codec chips on different PC's I have, a various Realtek chips sound and measure slightly different. I also noticed that the 'Audio In' is rather noisy and easily overloads on some of them. I would suspect the Codec chip or it's implementation. I have to fire up ARTA and play around. For sure something like RMI or older ESI PCI card measure much better.

[@tangerinq]

A cheap semi-pro usb audio interface comes to mind. Steinberg, Focusrite, Roland all make reasonable products. If you want to go high end and expensive (which i assume you don't), there is RME.

[@eto_675cebutech5]

Hi John what topology this amp?

[@HimanshuSharma-dm8ol]

Sir when i attach miller capacitor the sound becomes distorted when i increase the volume. But when i remove it the sound becomes ok.

[@highhat5229]

Will they be for sale?

[@EngineeringEssentials]

Do that driver transistor really need heatsinking?

[@mrmax1467]

Any unpopulated boards for sale?

[@lightbit553]

Nice amp. Make sure there is not some cheap software resampling causing distortion. What, if you lower the input volume even more?

[@cuongnguyenquoc6356]

Great video!.

[@montynorth3009]

Any thoughts on incorporating the preamp chip onto the board?

[@HamBands]

Hey John! Have you yet gotten a new replacement Snickers friend? I miss seeing the old Snickers trying to walk across your work bench. My cat is always doing the same thing.

[@benhoward3049]

Snickers died? Oh man that's really sad

[@mkepler5861]

hey John, this is mike, did you ever get the transformer for your amp project, if not let me know I'm still on board to get the transformers for you and me. mike

[@JohnAudioTech]

Hi Mike! I did not get a transformer yet. I will put some thought into the power supply of this thing.

[@mkepler5861]

@@JohnAudioTech its good to hear from you John, find a transformer that you feel would do your amp justice, and let me know. mike

[@souvicknaskar4538]

Hello Jhon sir What is the input impedance of this amplifier?

[@JohnAudioTech]

~22K

[@amirshokati6377]

tnx John, what do you think about using SMD parts for signal

[@JohnAudioTech]

For a kit, they are too small for most people to fumble around with but are great for boards assembled with machinery.

[@marciojpcardoso]

Should make this available as a DIY kit on eBay. I'd buy a pair.

[@matthewridgeway9250]

Nice router theremin!

[@amitghosh6966]

I have a request- Please do reviews of audio cassette , Cd/ Dvd player music systems that were popular in past and do tell the audio chips or transistor amplifiers used in them along with power test

[@dxhighendamplifiers]

I am missing your buddy....snickers

[@JohnAudioTech]

Hard to believe he has been gone for almost a month now. I miss him.

[@Algray_]

Hi John! I have made a board with your Pre-Amp (5532), it's very simple and only has the places for resistors and basic capacitors. Would you like me to send you the file?

[@JohnAudioTech]

Hi Algray, You can send to [e-mail] Thanks for your efforts!

[@Algray_]

@@JohnAudioTech Just sent you! Hope the read isn't too long :)

[@ionutzxpo]

It gets in the preamp because you use very high pass filter at the input of it ;) I don't know why everybody cut's down they'r preamps and amps at 100khz...300khz LOL! That's.....whaaatt? I cut my Class D amp's input at 35Khz! That's more than enough for audio band!

[@FindLiberty]

IMPRESSIVE first test and layout ideas. lol, that low low THD -sounded- _specification seems just_ too good to be true. I easily hear it when upper-end piano notes/chords are played (at the same time); _They buzz or create odd harmonics_. Hoping your design will fly. Sell some PCBs/Kits before knock-off copies appear from China!

[@bradleyberthold4606]

lol you really think you can hear under 1% distortion, over a youtube video? Give me a break.

[@FindLiberty]

@@bradleyberthold4606 TY - I've corrected and clarified my comment.

[@Jibs-HappyDesigns-990]

why no place the power in the middle of U'r planned re-location?..U'r heat sink could be much smaller.& thinner.. sound like electricity pulsing!! oh yup!! wireless will do it every time!!it attracts 2 anything metal...fyi... good luck with this!

[@KuntalGhosh]

Buy a separate usb audio recorder.. there is many good ones near 100$ with excellent audio quality and low noise profile.

[@KuntalGhosh]

Focusrite makes some good usb audio interface u can use to record the audio and do these thd tests.

[@DAVIDGREGORYKERR]

Change the sample rate to 96000KHZ