Power Supply Project for Class AB Amplifier - JAT Collaboration ep#1
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- Опубліковано 5 жов 2024
- In this video ‘Power Supply Project for Class AB amplifier - JAT Collaboration’, I’ll present the power supply idea or ideas for John’s Amplifier at JohnAudioTech. This will be our first Collaboration where I will design a Power Supply or Power Supplies (to compare) for this amplifier. I hope to develop the boards and have a way to make them available.
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I'm an Audio Engineer that mixes on arena sized PA systems. ALL of the amplifiers in the pro world now use SMPS due to the high output for less weight as well as all the reasons mentioned in the video. Not that us audio guys knew about all of the benefits mentioned but the lighter amplifiers alone made the switch a no brainer. Can't wait to see how this little powerhouse series turns out.
Thanks so much for this great feedback! I appreciate you!
I'm definitely encouraging you guys to choose the SMPS route. Especially since that's what I'm interested in learning 😊
I am really looking forward to your fully regulated, switch mode power supply design Eddie. I have a little bit of experience using both fully regulated switch mode and also completely unregulated switch mode and also "linearly" regulated power supplies. These aforementioned topologies were implemented in high-end, high power audio amplifiers, from which I accumulated experience over the last thirty (30), or so years with, but I do not have anywhere near as much power supply design experience as you have. I am very excited to be able to learn from your upcoming, fully regulated power supply solution/design(s). I am particularly keen on finding out what type of transformer (flat wire, toroidal, employing perhaps an optically isolated flyback design) and I am equally interested in the switching frequency of your power supply solution. Will you be using a PWM controller that employs a continuously variable duty cycle to maintain your secondary (positive/negative rails) capacitor reservoirs? You have definitely piqued my interest on this one Eddie and I look forward to learning what your final power supply design will ultimately look like. Fred
Great video Eddie, cheers!
Thanks so much! I appreciate you!
I've been waiting for this. I seen your first message to him and that's how I found your channel
Yes I was so hoping for this one! Now I got that of my chest let me watch the video :D
Perfect!
I follow you and John audio tech couple of years and I really like what you are doing , And now that the two of you build a ( kind of ) SMPS , Measuring with microcap , developing a pcb , Good job working together 🤗
Thanks Bert! Let me know what you think of this series as new videos come out;) I'll be interested in your feedback!
Looking forward to the project. Thanks for sharing.
Thanks so much!
Hi. Looking forward to see your next videos on this! Thank!
Thank you! I appreciate you!
This is getting very interesting. I am Looking forward to seeing the performance of the SMPS in the Analog Audio World. Great stuff.
Thanks Sparky! This should be fun and educational ;)
Hey Eddie. Love your channel. Always informative & explained in an easy to understand way. Looking forward to seeing you psu come to life. Keep up the great work!!
Thanks so much Arthur! I appreciate you!
Hi Eddie, thank you for the great video. 🙏
Thanks so much!
Remember a friend putting together a big power PA come HiFi MOSFET output stage high power audio amplifier (back in the 80's when it was all the rage to use such new-fangled devices) & out of interest he tried a commercially available SMPS (that was actually a spare part to other equipment) that while he waited for traditional mains transformers to be wound to order.... The SMPS had around +60V & -60V split rail supply. The amp ran fine but we noticed it would suddenly draw some big current during no input signal. It was the MOSFET stage that would randomly start to oscillate at around a crazy 100MHz! We could only believe the MOSFETS were seeing a weird as impedance looking back into that SMPS that tripped then becoming "RF oscillators".... Anyway the big transformers came in & he finished the project with the hefty as 'Linear' approach & the RF thing never happened....
Thanks for this great feedback! It could be that power supplies awhile back needed a minimal load or they would have higher ripple noise. This noise could have set off the MOSFETs if they didn't have a pull down resistor on the gate (which helps them stay off).
I really enjoyed this video and am really looking forward to the next installment. I believe your swps could be adapted easily to replace the "linear" power supply in one of my Hafler amps. I will be sure to watch your next video on this topic to see what might be involved. I'm not sure how to send a jpeg file of the schematic in this comment section, but if I figure it out, I will follow up with a schematic.
that is kinda a new approach to a seemingly already solved problem. Really curious of the result. Thanks for innovate 🙂
Thanks so much!
Sir your videos is highly useful thanks sir
How to test transformer max output power
Thanks so much!
I am looking forward to the development of this power supply. THX
I look forward to seeing your results for comparing a linear supply to a switcher! I like having built in current limiting on the power supply, along with all the other advantages you mentioned. However even though it is nice for preventing fires, it could still deliver quite a lot of power to a load in case of a speaker terminal short. You can still toast a speaker with 1A continuous DC because the air cooling motion ceases with DC. So you still need a smarter protection scheme built into an amplifier to save speakers and protect the amp itself from damage in case of a short. This is especially true of single supply bridged amplifiers that are lifted from ground.
This is quite exciting. It'll be great to have a solid amplifier power supply for amateurs like me who don't yet have the technical knowledge to design something this intricate.
I really enjoy your equipment reviews and explanations of newer technologies like the GaN chips as well. Keep up the good work!
I am a firm believer of the old school unregulated massively over built where size and heat and power consumption are not negatives in my camp lol 😂
But you now have me very interested in regulating my power supply using a combination of the two old school and newer improvements
Because I know power supply design is in your camp and switch mode power supplies is your profession and you’re going to be putting your heart and soul into this thing not being designed and marketed by a corporation with bean 🫘 counters.
Knowing your background watching your channel it looks like you got me building my first highly regulated/linear/kind of switch mode power supply lol 😂 and I believe it will be a superior product 👍
This is going to be fun
By the way the average big transformer recommended for Nelson Pass do it yourself projects the big boys around 500 VA to as much as 800VA so that 500VA IS a good minimum size to start with.
Thanks for this great response! I appreciate you!
Well there may be "hum", just not in an audible frequency. Great video!!!
Great point! Thanks!
Great. Waiting for the awesome series to start.
Hi, I hope yours is just a big provocation, now it is too early to tell if your approach in power supply design is right or wrong. The power supply is a defining element in the construction of a classy audio amplifier, not an accessory as is too often seen. This project interests me a lot, I'm waiting for the next episodes. Thank you very much and greetings from Italy. 😎
Sorry for my English.
How beautifully stated ! Your English appears wonderful to me. I will not be angered by the conclusion however, no matter which way the results point, but will continue on my quest to the " Absolute Sound ". ( electronically reproduced ) and take this as one more advancement toward that goal. I've never had the opportunity to be as close and one on one with a PS Engineer, focused on the Audio world, as Eddie has offered here . I too am anxiously waiting for the next episodes.
@@sparkyskinner4729 Oh thanks a lot! My thinking is that to condemn linear power supplies just because their only advantage is in ease of design is very simplistic. But it is too early to open a discussion on this topic, I prefer to wait and see how and where our Eddie will go in the next videos.
More and more power amps from renowned brands like for example Benchmark, NAD, Topping, Halcro are using SMPS. I don't know much about their specific topologies. I heard that some of them are tracking supplies, which increase voltage when needed. A friend of mine has the NAD and we still hear the power cables. 😄
Obrigado!
Thanks so much!!
Glad to know more about the design of switching power supply, some questions: Will the ultrafast diode help on the bridge? Now there are active rectify, will that help? Also will the super capacitor benefit in the "cleaning" process or not? Curious to know how they compare. Always thanks for your teachings.
Thanks for the great questions! I'll be sure we hit these points along the way in this series.
@@KissAnalog Sorry being a question boy, wish I'm not annoying.
I like the questions - so keep them coming;) I'll show how to select all these parts in this series.
I would like to see you design a voltage regulated linear power supply to be used as a comparison with a smps w/pf supply.
In class ab amplifier try to simulate with ac power and diode ratification and capacitor and find out that the output has little bit noises 😳 in it if using linear power supply because of rippel voltage that goes in to input stage how to fix
I appreciate you!
The opposition to the SMPS is coming from the "not easy" cons. I mean, 'anyone' that can put together an audio amp can size up a bridge rectifier and some caps, maybe put in a transistor or two for a linear power supply. I guess, less than 1% of them can design a SMPS with the same ratings. If anyone could design them at the drop of a hat, the resistance to them would drop as well.
Thanks for this feedback! What you say as a lot of truth - except the percentage is probably closer to 0.01% ;) Or maybe less, but I have a playlist of videos where I am teaching how to design them. It is taking a lot of videos from different perspectives so that I can fully cover the concepts. I just finished a video showing the issue with the low frequency switcher. This also took a number of videos and I just posted a summary video. ua-cam.com/video/sTiDKPl2FXA/v-deo.html
Now I'm back on the SMPS design;)
Have you thought about using a capacitance multiplier in addition to these big capacitors? All my friends use it and I've been shown that it reduces the ripple impressively.
Thanks for the great question. Are you referring to the regulated Linear PS? If so, yes it will have some type of capacitance multiplier;)
@@KissAnalog Thank you. Yes, I meant the llinear PS, although if it makes sense, why not use it on the switching one as well? It's interesting to me because I've seen great results with it, yet this circuit is still somewhat underexposed outside of forums. Especially the measured performance is something to behold. A comparison between it and a regular capacitor filter is a nice material for a video in itself i think.
I agree with you. This will make a great video. In switching power supplies it isn't really a thing. The feedback loop takes care of the regulation and is faster and more efficient.
Personally I would love to see you start with a SMPS. Many people already know how to make a standard linear PS. The biggest issue I have found with SMPS is which ones can you trust. The ICE SMPS (under a generic name) I have used with the 50 volt output version, and a number of my viewers have said they like to blow up! I also have had 2 of them fail for no apparent reason. Each time the rectangular potted item that contains quite a bit of circuitry completely blows it's self to bits. The distributor of these will not supply replacement parts so the complete PS is e waste.
Another issue is overheating, heatsinks too small on some units. These days I always use one with a fan.
If you are adding high frequency switching after your linear supply, I'm not sure it's really any better than a SMPS. The cost must be double, but what more will you get in the real world? A bit more efficiency on the mains transformer. Expensive and large for just a little more efficiency on power draw maybe?
Thanks for the great feedback Michael! I have looked at the ICE chips but don't know much about the PS using the ICE name - presumably because they use the ICE chips;) I'll look into these for comparison to other options. I like the name, but maybe I don't know if I want to use the ICE name since others have:)
I think the trouble is that to make a large power output from your amp you need a large power input. How much would it cost to produce or buy an smps that can kick 2000w for a power amp constantly compared to a toroidal transformer and filtering?
Also you could use opto couplers to measure the rail current across shunts then have relay protection for both speaker and supply that would run off a seperate low voltage regulated supply. It would need to make use of a power on off circuit that can inhibit restart so it doesnt constantly loop on off on off until its reset.
This is the epic question! Thank you! the switching power supply would be lower cost and provide a regulated power supply which the low switching power supply can not compete.
As a fellow EE working in the broadcast industry for 30+ years, as well as an active electronics hobbyist since childhood, here are my thoughts! I must agree with Douglass Self and Randy Sloan, who both say the best amplifier power supply is a simple unregulated rectifier / capacitor supply. I have tried both over the years and I too find simple power supplies sound the best.
Now, that's not to say you are wrong and I know another respected EE who plays in your camp of regulated supplies always! Here is what I think is going on:
An un-regulalted power supply is going to sag even at modest listening levels. That is a fact and can be easily measured. So what does this rail sag mean n terms of sonics? Well it will modulate the amplifier gain to the extent of the power rail sag. Now remember DBX in the 1970s (sorry, you and I and I are about the same age). they made numerous dynamic range expander products based on various VCA technology and in the end right before CD in the mid 1980s, they were quite good. I still use one today even with streamed audio.
Well the fluctuating power rails would tend to produce the same effects in a power amplifier, the severity depending on the circuit topology. And most people like that effect. But is it sonically accurate? No, I don't think so. Critics of power amp supply regulation point this out, claiming such designs sound flat. And based on listening tests I must agree. But which is right? The job of a power amplifier is to reproduce the signal exactly except with enormous power gain, nothing more. Does a regulated rail power amp accomplish this? Yes I think it does. But does it sound good to us compared to an unregulated power supply? Perhaps not. But again the amplifier should not be an effects processor. Leave that now to modern DSP technology that could create a killer dynamic range expander without the pumping issues of the old DBX units by delaying the audio and applying gain coefficient at the exact proper time in the audio data stream.
All my DIY home theater power amps, 24 channels worth for Dolby Atmos, are classic unregulated simple power supplies with exception of the LCR main speakers triamped class A tweeter amps. These are a single ended SE with a current sink. They produce 20 watts max but each amp consumes 2.7 amps with +/- 24v even at idle. As +24v was a popular voltage for larger legacy disk drives, there are plenty of NOS surplus 24v, 300w+ SMPS power supplies to be had cheap. So I used a couple for +/-24V. Though I took only reasonable engineering noise precautions, I have zero issues with EMI/RFI. I checked it! And these are open frame PC board supplies to boot! No shielding! But then for a class A SE tweeter amp, the load is fairly constant anyway so this is not a good comparison of regulated/unregulated power amp analysis.
Just my thoughts on this subject.
A power amp is a power amp, it's deliberately not a static regulator imo.
@@johnshaw359 I'm not sure what you mean? The discussion here is about the benefits and disadvantages of regulated power supplies for audio amplifiers.
@@andydelle4509 I mean it should be free running not restricted it only has to deliver AC power into varying impedances, so I don't see the point of adding rail regulation that will also have a delay in its response time to deliver the extra current needed for fast transients. SMPS are inherently regulated, so no option if using one.
If you want to win over the audiofools, make it a polyphase output so you can use a buzzword that isn't "switching."
LOL - thanks for that idea;)
I think it is funny that you call conventional unregulated supplies switchers. Please have a look at choke (Inductor) input power supplies. I have seen high end companies occasionally use these. I refer to them as the original switcher. It is covered in the Radiotron Designers Handbook.
BTW... Do you ever fly the helichopter at the top of your rack?
LOL when I find the remote unpacking my storage - then I'll have to try. It has never flown;)
Eddie...We all need an adult libation, after a hard work week!
Yes Don, I agree;) Thanks!
I was expecting loads of LM338 regulators. Seen that all too often.
Thanks!
can you please do a clip about opamp fedback compensation regarding linear power supply? i mean using a opamp to control a transistor or mosfet is so hard to get it stable under series of conditions. I think everyone should do their own linear psu before into the high end.........
Question, will You use an active rectifier bridge in this power supply (e.g. based on mosfets)?
I am asking because you are going to create a project of a switching power supply that can become a power source for many project and not only amplifiers, and because it is a high-power PSU, the use of such a bridge will reduce power losses.
I have been searching YT on this topic for some time now and there aren't many interesting materials, and even if someone does it, they create a power supply with a ridiculously low power, completely ignoring the legitimacy of using this solution.
I think you're waveform is going to have some bad ringing on the output. It needs a clamp to chassis using a zener to inductor with an x2 from chassis to input...lol
I'm yanking your chain. Very cool video Ed.
LOL you funny guy! ;)
Does all of this really mean that much if you keep enough headroom to not go near the rails?
Hello sir, how are u pls I want to no how to calculate output impedance ohms amplifier.
Thanks for the great question! I will do a video on this very soon.
Hi, I have a general question for powesupply components. I'm in the process to build a linear power supply, 18V to my streamer. As a base I have Chinese kit plus an R-core transformer. My question is, I assume that the quality of these components might not be the highest so if I'm about to replace some which should I start with to get the best sound out of my new supply? What would be the second choice?
Thanks for asking. What specific components are you concerned with? In general, I'd recommend using Vishay parts (or Bourns, Littelfuse, or EPCOS). These companies own many good companies of various parts.
@@KissAnalog Thanks for your answer but let me rephrase the question. Out of the parts should I go for the best transformer, or the best capacitors or maybe the best resistors. What would give me the best sound improvement?
That’s a great question. You need a transformer that can deliver the power needed without drooping too much in voltage, but it doesn’t have to have a great brand name;) The caps are very important to be sized big enough, but going bigger or better is not going to pay off either, but can make up a little for an undersized transformer. The resistors are all great these days (metal film is everywhere).
@@KissAnalog Thank you, that puts my mind at ease.....
yeah microcap are you going to print the schematics? are you going to make it selectable for different output voltages?
Thanks for the great questions! I will provide schematics and I will show how to make it flexible;)
@@KissAnalog
I was thinking is it not better to have it auto selectable for different voltages? up to 52 volts
and to cope with high consumption demands, say 900 Watts so less stress on the power supply!
@@KissAnalog another thing came to mind could you not have a chip to Bluetooth it to your phone to see wave patterns, draw current, voltages, and digital filtering, you can put in yourself like a 5 band EQ where the user can change the frequency of each band manually so you could just have low frequency or mid-range and just highs, so you can fine adjust your own slight filtering to +/-2db. i don't know of anything like that and that would be really good for multiple different types equipment.
Great idea for the amp section!
@@KissAnalog
what amp section in the power supply?
Antek tx @ 500v is about 70$ us..
That was my first thought when he said 100. I figured with shipping, close enough. The point he was making still stands
Thanks for the tip. There is a large quality difference between Toroid Transformer manufacturers. So, I was going with a proven (to me) vendor, but maybe Antek is just as good?
Antek is really nice IMO. @@KissAnalog
I should be getting "filthy" rich soon when I open my new school that teaches the new generations different "strategies" and efficient "algorithms" for doing the way you laugh. Would love to have you as an honorary guest professor from time to time (and to share the filth ;) ). Another project I did is I downloaded all your simulation software tutorials (with the free software that I have never hear of before you brought it up because I never in my life time owned $4700) and will start selling them as a course to the unknowing and send you a commission if you are as an unrighteous opportunist as myself. Thank you boss, you got me hooked
I have a quick question from a junior piece of nothing (me) to a power electronics expert (you). I am trying to choose the gauge of a couple of feet of wire to use to supply a load of about 200A (close to short circuit) from a car battery that only works for 10-20 milliseconds at a time. My idea is to use a gauge that would stand a fraction of the 200A continuous and to take the whole resistance of the load and the wire (to be chosen) read with a milliohmeter or a current source+voltmeter in to consideration, but is there a real math out there? what do you think? I am pretty confident that you had to make that choice through the years.
in (Vegas) - out (family)
what you do in Vegas, stays in Vegas, nothing to do with family. Your family stays untouched. I like to think this way how SMPS work
LOL thank you!
SMPS, yes! Switcher + AB. I am amazed at how the audiofools spend so much on power cables, yet the power supplies in their hifalutin amps ARE NOT REGULATED! Duh! SMPS is the way of the future. Linear regulation is no longer acceptable as it's not efficient enough.
Although you are switching at 100khz which is out of our hearing, but the pwm regulation can inject audio freq noise on top of the 100khz. What is your plan to avoid pwm modulation noise?
Thanks for the question! Are you referring to the feedback bandwidth? We'll have to see what if any modulation we get. The output will be closely regulated, so I don't think we will see much there.
@@KissAnalog I think that is what I am talking about. I am not a power supply guy so I don't know the best terminology. But my understanding is that the feedback can modulate the switching base frequency at an audible frequency.
Thanks Ed - great question! A switch mode power supply should not be audible. But there are cases that it can if not done correctly. I'll try to point these out as we go along.
Aim for at least 500w
Amps/ Speakers are power hungry
I love the cocaine. I love cocaine. Momma won't you wait! Good tune
LOL - you are having too much fun;)
@@KissAnalog those days are behind me lol
Dirty little RF switchers Vs clean mains frequency magnetic collapse. Bah, humbug. You can't even power a small portable radio for the noise from switchers, they're only good for charging phones.