JAT501 audio amplifier power tests on transformer supply

[@cassvirgillo3395]

Hey John, Good to see you again. Good job designing and building your amp. Great explanations about power supply and test. We (subs) will be here as your able, and, Thank you for all you do. I wish you, your Brother and your folks all the best, stay strong, C.

[@isoguy.]

Hey Dude, been missing you and your vids. Looking forward to the next post

[@curtislucka9954]

I like your videos - you are very resourceful. It is an inspiration for those of us with surplus components lying around! Why not use what we have on hand...

[@TheTrueVoiceOfReason]

Always good to see a new vid or post from you. (And Snickers!!) How close do you think the JAT501 is to ready? It's quite a nice design that would benefit from some board design time for "final testing." Wishing you all the best.

[@fabiotrevisan8922]

Hi John, it's been a pleasure to watch your videos since I came to know about your channel, probably an year ago or so. It was entertaining and informative to follow you on the JAT 501 project... The way you approacehd it and how you talk and explain things very clear and fun to watch, and pretty much correct in every respect (I know a bit the subject and share most of your views on circuits and concepts in general). I decided to put a comment on this video in particular beacuse it's about the power supply. It's a known fact that PS ripple subtracts from the available power and when pushed at its limit, the amplifier increases distortion. It's also known that bass is the the audio frequency that's mostly responsible for the depletion of the P.S. stored energy and, finally, that in a stereo program, the bass content is pretty much monophonic. So, I would love to hear your thoughts on the following (and maybe a video if you feel it's an interesting subject): In commonplace Stereo Amplifiers with linear, non-regulated power supplies, why nobody (that I know of) makes the channels work in opposite phases, and ultimately connecting the output speaker of one channel in reverse (on the inverted channel) and by doing so, distribute the voltage sag of the P.S. rails throughout both rails, instead of what happens in pretty much every case that I know, during the peak of the bass semicycles, each P.S. rail is depleted in alternate fashion, making that the power be limited and distortion increased by the double sag, while one channel could be depleting the positive rail while the other could be depleting the negative rail. Given the same power transformer, rectifier and smoothing capacitors, how much power could be gained by using this technique (at a given distortion level, before the P.S. sag would lead to premature clipping). Sure I reckon the overall sag spreads through many cycles and it's unavoidable that both rails will eventuall sag equally (over medium term), but in music program, quite an expressive part of the high powered peaks are short-term that happens only every once in a while... Isn't there nothing to be gained here?

[@JohnAudioTech]

Thanks for watching the channel! I think you covered it in the last paragraph. The waveform of a bass note would change polarity in short order, loading both rails of the supply. The filter caps should be sized to handle several cycles. This would balance out the load on the each rail. If you were using undersized filter caps I can see your idea working to some extent, but seems to me to be unnecessary with proper sized caps.

[@VIPINSAINI_20]

Love to see working on Rewinding that Toroidal Transformer, and those Amplifier boards , you just mentioned 😄

[@richardmiller4388]

Nice video, John. I am a long term audio amp design addict and enjoy your videos, reviews, designs and critiques. Well done and thorough. Is the JAT501 the design you had planned on making a circuit board (and possibly a kit) for? If so, did that ever come to fruition? Keep up the good work. Thanks.

[@JohnAudioTech]

I still want to make boards for it. I need to learn some layout cad software. I have a lot going on and haven't put the time into it. For now I dropped the idea of a kit. It is just too much effort to manage stock and sales.

[@richardmiller4388]

@@JohnAudioTech I understand. Can be a PITA managing inventory and becoming a retailer.

[@nareshnarasimhan9774]

Can you consider doing a IC driver input with the traditional discrete output stage

[@tebbi67]

Good Work! THX for the Video.

[@Neovo.Geesink]

Missing the connection dot at the 0-Volt point of the two rail capacitors @ 2:38 a.f. ... That should be a connection though?

[@AnthonyPrechtl]

At 12:00 you mention the bouncing waveform... how do you fix that? Higher VA rating on the transformer? Bigger filter capacitors?

[@JohnAudioTech]

Larger filter caps / better filter design to lower the ripple.

[@bobisyouruncle1]

Hi John - what amplitude did you use for the 1khz dynamic test signal? You mentioned your music player and i guess it feeds into your pre amplifier, in turn feeding the JAT. My logic is that for a dynamic test, your test signal amplitude must be greater than the anticipated power amplifier output.?

[@JohnAudioTech]

I had to perform a couple test runs to set the amplifier for max output without clipping at the dynamic peak or the test would not have been accurate.

[@bobisyouruncle1]

@@JohnAudioTech Thank you, John.

[@VIPINSAINI_20]

That Toroidal after Rewinding will be able to delivery enough power for lm3886 board , you received recently, I'm very interested in that Toroidal rewinding video, because I also have one toroidal with 18-0-18 14awg wire, 12-0-12 20awg wire winding, and I'm thinking about Rewinding that too. So I love to see you work. It'll be interesting and big help. I already assembled 2 TDA7294 BTL Stereo/Mono boards and 2 Mono lm3886 boards,

[@electronicssciencebysherry5050]

Interesting thanks

[@gkdresden]

John, what do you think about a switched mode power supply for the JAT501?

[@maker-matt]

You made me laugh, I have not heard anyone say "Its the transistors that protect the fuses" an many - many years. Like an IC will quit working if the smoke leaks out.

[@victimovtalent6036]

John,why not 220vac power line in your area?

[@HillsWorkbench]

In North America (NEMA code) we run 240VAC only to major appliances, like a clothes dryer or range, 120VAC to everything else.

[@carlfranz6805]

Could you increase your volume? Some of us listen in an imperfect environment.

[@alexfaustino5412]

3:06 depois da fonte ao retificar o negativo e positivo o zero ali no desenho dele,so poderia ser o nosso neutro. Veja o desenho dele? Ele separou o negativo do positivo no ponto zero so poderia ser o neutro.

[@alexfaustino5412]

Creio que o neutro ocorre quando as cargas magneticas negativa e positiva negativa se anulam. Quer dizer no centro do ima?

[@bravo1412]

1 question. 60w rms amp 8ohm x2= 120VA is OK @ 8 ohm, but the Most Speakers now are 4-8ohm. It is better to use the 4ohme RMS. Ideal 60w rms 8ohme = 120w rms 4 ohm x 2 =240VA. So de VA specification depends on the load?. it's always better to have more than not enough VA. And the ripple voltage is less. Or iám wrong? Thank you very much and good luck with the baby birds!!

[@vidanmitkovski7785]

Hey there I would like to know something about power resistors in the output stage of amplifiers. What if their value is higher than needed or less? I have a situation with my diy output stage where 0.22 ohms resistors are needed and i only have 0.33 ohm...will they do the job or there will be a problem?

[@akkudakkupl]

It will be OK. You will get better temp stability and some lose in efficiency.

[@vidanmitkovski7785]

@@akkudakkupl Thanks man 😁

[@1pcfred]

I thought the transformer looked good but it sure could not perform. You might be able to rewind a microwave oven transformer too? They're usually good to around 1000 Watts.

[@firuzpulatov7750]

mw transformers core does not have electric isolation between sheets and get hot. In normal use that does not matter, ovens work for not too long periods. In amp that could lead to overheat.

[@bob-ii8oe]

mr Samford and his ripple ..

[@sasmit82]

quite like this amplifier, very simple design and great performance even on perf board. Perfect to start diy adventure in builiding amps. I designed a PCB for this , cant say its perfect. Comments welcome ! drive.google.com/file/d/1E4vD0UhUS0culaR7DDquaYE36qCteMh2/view?usp=sharing

[@MrDunk66]

Stop the amplifier board testing - I have become an Aliexpress Super Buyer 😀😀😀😀😀😀