20 Watt Class-A Power Amplifier Fail

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This video is titled; 20 Watt Class-A Power Amplifier Fail. This is a Class A Power Amplifier I purchased for my power amplifier project. But I'll show how this Power Amplifier board doesn't actually meet the rated power. #20WattClassAamplifier #20WClassAamplifier #ClassAamplifier
Yaung Jing is the brand, and the following is the specifications for it:
Basic Parameters
Supply voltage: DC +/-25V ~ +/-35V
Output power: 20W @ 8 Ohm, 40W @ 4 Ohm, 80W @ 2 Ohm
Speaker impedance: ohm 2 ~ 8 Ohm
Link to 20W Power Amplifier Board: amzn.to/3oB0VWW
Link to silicone lead set: amzn.to/3j23ksq
Link to Blue silicone mat: amzn.to/36qpIqD
Please use this link for the Hiraga Power supply kit:
rover.ebay.com... Power Supply
Please use this link for Aleph 5, Class A Amplifier kit used in this project: rover.ebay.com/...
Another Aleph 5 Class A amplifier link:
rover.ebay.com... 5 Amplifier
Bridge Rectifier with capacitors: rover.ebay.com... with Capacitor bank
Link to Hiraga power supply kit: rover.ebay.com... Power
Adjustable PCB holder: amzn.to/2XhH1pe
1 Ohm 3 Watt metal film resistors: amzn.to/2BO0h64
Audio Grade 220 uF 35 V capacitor: amzn.to/2BNFbET
Silver Solder: amzn.to/2Dv7wQL
Soldering Iron T12 tip: amzn.to/39MQARR
Heatsink TO-220: amzn.to/3gkO8EB
Thermal Paste: amzn.to/3i1AZ43
You can support this channel with this link to Patreon - I really do appreciate your support? This support helps me purchase the equipment I use for testing a reviews.
Patreon.com/KissAnalog
Or you can support this channel with a one time donation on PayPal at: KissAnalog@gmail.com
LInk to Class D Amplifier Playlist: • Class D Amplifier
Link to Part 1: How Class D Amps Work: • How Class D Amplifiers...
Link for preamp with bluetooth: amzn.to/39JzyTp
Part 5: listening test: • GaN Class D Review; Li...
Part 4: Intermodulation Distortion (IMD): • GaN Class D Review Int...
Part 3: Amplifier Distortion and THD: • GaN Class D Review Dis...
Part 2: temperature rise at 150 Watts out: • GaN Class D Review Tem...
Part 1: gain/phase plot across the audio spectrum with this GaN Class D Amplifier: • GaN Class D Review Gai...
First video in series: Future of Power Electronics GaN MOSFET: • Future of Power Electr...
Popular Links:
Micro-cap Tutorials playlist link: Micro-Cap • Micro-Cap
Boost Converter Introduction • Boost Converter Introd...
Power supply talk: • Power Supply Types and...
Link to Amazon for Boost Converter: amzn.to/32HOEFsY
Link to FLIR meters in Amazon:
FLIR DM92 multimeter: amzn.to/2ztKOXI
FLIR DM93 multimeter: amzn.to/3ebyASF
LInk to Amazon Commercial 90DM610 multimeter: amzn.to/37VXe7E
Music I used for this is credited here:
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I'm Just Good by Johny Grimes / johny-grimes
Creative Commons - Attribution 3.0 Unported - CC BY 3.0
Free Download / Stream: bit.ly/im-just-...
Music promoted by Audio Library • I'm Just Good - Johny ...
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🎵 Track Info:
Title: I'm Just Good by Johny Grimes
Genre and Mood: Hip Hop & Rap + Inspirational
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🎧 Available on:
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SoundCloud: / j...
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😊 Contact the Artist:
/ johny-grimes
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ru-vid.com...
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29 авг 2024

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Комментарии : 89

@littlebitstrouds 3 года назад

Love your channel. As an engineer in a different field, new to electrical engineering, I can appreciate how you explain things. Would you ever be down to do a VC to chat about me helping you out in video production? I think I have a few tips you'd appreciate.

@KissAnalog 3 года назад

Thank you very much! You bet. I'm always trying to improve;)

@DominicDsouza5 3 года назад

@@KissAnalog which digital amp 20w per 2.1 channel would you recommend

@versace885 3 года назад

Hi Eddie, I really appreciate the time that you put in showing these great videos. Thank you

@KissAnalog 3 года назад

You are very welcome. Thank you for your support!

@agrimm61 3 года назад

Discovered your channel tonight. Your content is entertaining, educational and delivers ASMR at the same time. I would like to thank you for the effort you put into the production of those videos. Subbed.

@KissAnalog 3 года назад

Welcome aboard! I really appreciate you! Thanks for joining;)

@friedmule5403 3 года назад

Great video and strange about the volume level. I may have an idea to you, to make it easier for you to hide cuts, and to help the viewer to follow along. When you are finished recording your video, then take photos or video of things you was talking about or are using. Now when you have a cut, can you place a photo/video of what you are talking about, over the cut. Just try it and see if it's easier to do that, maybe try to look at an interview in TV to see how they place those recordings over the recording of the interview. :-)

@KissAnalog 3 года назад

That's a great idea! Thank you, I'll give it a try;)

@MichaelBeeny 3 года назад

When I was building my L12/2 for my RU-vid channel, my first tests was using just 25/0/25 volts as I was waiting for a transformer. I must say I was a little disappointed with the results. It did get quite loud but something was missing. After I received the correct transformer to give me 50/0/50 after rectifier, wow what a difference. Huge dynamic range, just brought out all the detail, 110 watts into 8 ohms, double into 4. Real watts, not Chinese watts. Regarding your test amplifier, seams an odd thing to do, capping the internal working voltage at all, at such a low level. My be it's a dissipation issue. More volts more amps? It looks like they are selling class A rather than a useful amplifier. I think class A is one of those ideas than in theory it MUST be better, but I have not found that to be true. A good quality class A/B amplifier (like the L12/2 with high power, always sounds better, mostly due to high dynamic range. Fatigue free is the best description I can offer. Stay as far as possible away from clipping!!

@KissAnalog 3 года назад

Thanks for the great feedback! I agree on all your points here! Isn't it amazing what voltage level does for dynamics? I think a huge problem with Class A is that if you do have the voltage level, then your power level is crazy inefficient. Someone commented that Pass claims 25% to impress how inefficient Class A needs to be to be good, but even 25% might be too conservative. I think Class A may only be good for headphone amps (in the Winter);) Regulating the input stage is fine and actually may have some great merit, but it can not control and should not control the range at the output. This amp it does, and I think that it might be unwise to place a gain at the output of this amp as it is claimed to be 'no feedback'.

@nicoras8803 3 года назад

I have been designing amplifiers and in particular Class A for over 40 years. The trade-off is heat for output power and that is why these things are not as powerful as one would like. The class A designs are not really designed for varying voltage since thebias current is fixed as they are never turned off. Go look at some early designs like John Lindsey Hood, Jean Hiraga, Nelson Pass First Watt and the like, there you will get a better understanding of how class A works. Its characteristic is a perfect output until you reach the design limit and then the sound just falls apart completely. The reason is that the output current is limited, and for good reason, for good reason, it must stay well in the safe operating region of the device. This type of amplifier is unlike that of class B where you can increase the operating voltage rail and will increase the output until you reach the limit where you actually destroy the devices. The class A amplifier is very inefficient some as low as 15% and puts out much more heat than the output power it produces therefore the power supply is normally very large and filled with capacitors to keep the voltage as constant as possible. The average listening power required for a fairly large room is about 3 - 4 watt (on efficient speakers) only, peaks may reach quite a bit higher, but the amplifier is limited to the design bias current in the output devices, increasing the supply voltage only makes them run hotter since they have to dissipate more heat and will be destroyed. I suggest changing your speaker for something efficient like a Klipsh, Tanoy, or the like that performs at close to or over 90 dB SPL per watt/meter and it will blow you out of the room. Class A amplifiers has the advantage that they only generate even-order harmonics and the reason for their warm and easy sound, other amplifiers that produce many odd order harmonics (dissonant) sound maybe clearer or clinical, but edges are ruff and unrefined, if I could refer the effect of applying the "sharpen" function to a picture file, it only appears as if you are enhancing detail, but you do not. You cannot add detail that was not there in the first place. That is the reason other topologies of amplifiers sound the way they do, they have no timber, and the sound is not correct let alone fatiguing. Nice channel I will follow it with interest.

@KissAnalog 3 года назад

Wow - that’s awesome to have you here Nico!! Ok so I have designed a Class-A in the past, but years ago. I then went to Class A-B not only for effeciency but to get the peaks or more dynamic range. As you say, that’s where Class A has trouble. What’s your thoughts in that regard? The power level, efficiency, and room size that you describe. Is that for nice music levels or load R&R that you can jam too. So what I mean is what kind of sound level would you add to your description? Thank you for sharing your knowledge!

@nicoras8803 3 года назад

@@KissAnalog Hi Eddie, thanks for the welcome. In my opinion a realistic listening level (asume vocals) is that you hear the person singing in front of you at the same level you would expect in real life, the instruments are secondary, that you can do nothing about since it is in the mastering. Heavy rock is different, realistic listening levels would be at some point you imagine yourself being at the concert. Most non-audiophiles turn the volume knob up too far and although it seems louder all you are down is running into gain compression and although it sounds louder it becomes worse, but the amount of FUZZ and effects on the instruments make it difficult if not impossible to realize you are listening too, maybe your amp falling apart, that is the reason for sizing your amp with speakers in a room that would offer you that pleasure, decent sound. Those who purchase amplifiers of thousands of watts are either absolute imbeciles or have no idea what they are doing, unless you run very inefficient low impedance speakers that would need plenty of drive current to even make a squeak. These speakers are always designed to be perfectly pure and has so many cross-over components that to tailor the sound for perfect measurement that they need 100s of watt to produce moderate to reasonable listening levels. Just looking at the board in your hand, it seems too sophisticated to be rubbish, no-one in his right mind throws so many components into a class A amplifier, unless his idea was to create a "house sound"i.e. something the designer liked by the use of foregoing stages, everyone does that even the purest and biggest names in the audio industry such as Mark Levinson, Nelson Pass and all those famous guys. However, they have pure tone and can hear deficiencies in the sound and will correct what they hear (not necessarily measure alone). You do not find a tone-deaf audio designer, nobody will buy is stuff. Besides measurement, listening is the ultimate test, it can measure anyway you design it, and you can but if it sounds crap then that is your end. Try and get the schematic from the designer, seller and let's take it from there. I am retired and have not much else to do. I design amplifiers just for fun now to see what I can do with the least number of components. I will help you where I can and anyone is welcome to some advice.

@nicoras8803 3 года назад

@@KissAnalog Dynamic range is not always well understood, but it is the ratio between the softest and loudest sound that an amplifier or anything will produce. If you are listing to a program with a tiny triangle playing and you just hear it followed by a crescendo of the whole orchestra, that is dynamic range, It is the lowest signal, normally the noise floor of the amp compared to the loudest signal and expressed in dB. Headroom on the other hand is really some fictitious idea that the amp can produce sudden loud instantaneous passages. Yes this is done in crummy cheap equipment to amplifiers with insufficient power supplies and the power supply capacitance was totally relied on to produce the sudden surge of energy, this was dubbed headroom. From this the rule of thumb was developed that for every peak amp you require, you added 1000 uF to the supply rail. The run-of-the-mill amplifiers still practice this because it is cost-effective. However, properly designed and beefy power supplies will give you the best performance out of your equipment. Think of an amplifier as a device that modulates the power supply, nothing more. If you like you can mail me (nico@ras.mobi) I actually enjoy helping people achieve perfection in their designs or making it as good as practically possible. It passes my time until I die.

@nicoras8803 3 года назад

@@KissAnalog It seems that it did not post again, it was a long answer that contained my e-mail address. So lets try and fool the system nico(at)ras(dot)mobi. I am very happy assisting, what else do I have to do.

@nicoras8803 3 года назад

Looks like RU-vid squashes replies containing an e-mail address, this was the third time I wrote a very longwinded but accurate reply. I am not sure how to offer you my e-mail adress and hopefully I can discuss some of your concerns.

@andrey2149 10 месяцев назад

I didn’t think that the power of a home audio amplifier should be in the first place of importance; I used to think that low distortion and harmonic spectrum were more important.

@johnshaw359 3 года назад

Thought this might explain or help. Note: In order to reduce the hassle of installing the heat sink, the board adopts the CNC machining center carved radiator aluminum plate, but also need to be connected with a large radiator, otherwise it will be burnt because of over heat. There is test point on the board "TEXT", from the white power resistor 0.22ohm to know, if measured TEST point is 22MV, the quiescent current is 100MA X2 = 200MA, X2 is because the tube in parallel. if measured at 130MV, the quiescent current is close to 1A. Clockwise quiescent current decreases, anti-clockwise quiescent current increases. It seems they may have "turned things down" because the transistors will burn if you don't have the required heat sink.

@KissAnalog 3 года назад

Thanks for the great feedback #john shaw! You might be right, but they should have spec'd it at 8 Watts then. There was very little information with this. What you show above for setting the bias is the most I've found. Maybe the original design had directions on how to set it up for 20 Watts.

@johnshaw359 3 года назад

@@KissAnalog I think if you get the bias setting correct with the required heat sink you can get the rated output. I believe the makers set a "power limit" this to stop people connecting the board and then over heating the transistors and then returning them after they overheated. I would expect the amp to consume about 60-80 watts idle when it set up correctly however you will need adequate heat sinking to dissipate the heat. You will need to crank on the bias pot for it to work correctly by the sound of the instructions. These are monoblocks with 4 transistors, they must be good for at least 15 Watts class A. Now you see why Class A amps are not for everyone. Not sure you can fail this amp until you get it set up correctly..

@HillsWorkbench 3 года назад

I think part of the issue is your speakers aren't efficient, but is that amp really making its rated output before clipping? If the clipping isn't symmetrical there is usually an adjustment to center the amp.

@KissAnalog 3 года назад

Thanks for the great feedback! Check this video out, it explains further what is going on. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE--VRcelNAcP0.html

@coldfinger459sub0 3 года назад

It would only be good on 95+ DB efficient speakers where are you at only need one WATT to get louder output by just using one WATT of power. Like I said in the very first video on this class a amplifier they were dreaming advertising that as a 20 W class a amplifier not even rolling downhill with a back wind pushing it couldn’t even dream of approaching 20 W. And I was a D student in electronics class and just at first glance without studying it was that obvious

@nicoras8803 3 года назад

Most people will quote the peak output power for class A else it would be ridiculously low. People will just not buy it. A well-designed class A amp actually sounds louder than you would expect since it is much cleaner sounding. SE (Single ended sounds even better since it generates only second harmonic, but the efficiency is atrocious, 15% is a good figure to co by.

@coldfinger459sub0 3 года назад

@@nicoras8803 exactly, And who cares if it’s not efficient , it sounds good that’s the important part. And in San Francisco the little extra added heat is a bonus.

@KissAnalog 3 года назад

Thanks for the great communications here! It is awesome to see this community growing! By now I've come out with more videos that helped answer these questions;)

@timothygrupp 3 года назад

Was this sold as 20W RMS? It would appear that the specification is for PEAK power perhaps. I would agree that power supplies are the issue with this...for example that NE5532 op amp on the input doesn't really hit it's stride until the supplies are +/-18Vdc. For audio work and class A you need a supply with enough stored energy to deliver on the transients attacks of the music. Don't you just love the Chinese marketing, take this for example: "Pure class A output, each channel can output 10W, equivalent to 40W of class AB and 80W of digital amplifier. Enough to drive most home desktop/bookshelf/indoor/floor-standing speakers." (So how does 10W become 40W...just change to a class AB amp...really!?!) The amp described by this ad had a power supply featuring a 130VA air core toroid transformer and use Vishay Roederstein capacitors.

@PeterMilanovski 3 года назад

They are terrible, did they remember to mention in the description that it has feever capacitors? LoL... This amplifier is a copy of something old and much much better, but they have used something that it wasn't designed to work with, I'm putting my money on those output stage transistors, the majority of old school amplifiers used the T03 2N3055, I reckon if those were dropped in, the amplifier would come good instantly, I have seen it myself with other amplifiers and john from John Audio Tec's channel ran into the same problems! Someone sent in an amplifier to assemble and also gave him a set of MJE transistors which were supposed to be much better than what the kit came with, the kit's T03 2N3055's looked as fake as they come out of China, so he decided not to use them, but he had problems right from the start! He finally decided to throw in those fake looking thing's and wouldn't you know it! They worked, and all the distortion disappeared! Just like that... So that's why I think that it's the output transistor's...

@KissAnalog 3 года назад

Great question Tim, sorry to get back so late. By now I have a few more videos out that answered this question;) I am going to actually try to step up the power once more;)

@nicoras8803 3 года назад

Must say you have collected a serious number of test equipment there. How do I get hold of you, every time I post my e-mail, I get taken down. If it is audio or RF I am willing to offer you as much experience as I can.

@KissAnalog 3 года назад

Thanks Nico! Have you tried emailing a KissAnalog@gmail.com

@martinda7446 2 года назад

I just checked the link to amp supplier and it doesn't say the power AT ALL! apart from 20W and 2-8 ohm... I guess they saw your video. If I saw this and had no idea I would have guessed from power supplies suggested that it would be giving the 20W into 4 ohms. It suggests a 25v supply, which if all is perfect would give you exactly 10W RMS into 8 ohms. If as you say there is no voltage gain post op-amp, then again. if the op-amp was ideal you could expect no more than 15W, and of course in practice you will not get that.. Seems like a 10W design as it sits. Weird. Looking forward to your op-amp mods I saw listed in your homepage.

@KissAnalog Год назад

Thanks Martin for your great feedback!! Have you watched the videos in the playlist where I switched OpAmps and made modifications?

@martinda7446 Год назад

@@KissAnalog I will for sure. Great channel.

@MassimoTava 3 года назад

Why is the Purifi module so good? Maybe a topic for another video.

@KissAnalog 3 года назад

Thank you! I do like this bluetooth preamp! I'll definitely showcase it in its own video;)

@sunuk1915 3 года назад

TO-03 package stainless casing approx 5to7cent and aluminium casing approx 12-15cent

@KissAnalog 3 года назад

The cans are steal, and not aluminum. Is that an indication that they are not real?

@sunuk1915 3 года назад

@@KissAnalogthose are expensive one Good heat dissipation Thank you

@sunuk1915 3 года назад

Stainless steel vs aluminium , Aluminium better heat dissipation, But both are inside same silicon wafer, Manufacturers cost savings on theirs wire bonding and packaging

@PeterMilanovski 3 года назад

I would be probing and comparing the input and output of the opamp first to see if it's just a buffer stage or if it's adding some voltage gain and see if the sine wave is being distorted at that point, if that checked out ok, I would trace the next point, I see two transistors on heatsinks, if they aren't voltage regulators, then they are the output drivers and I would check out the signal at their base to see if the signal is clipped before or after! It would be a great shame to give up so soon without checking to see where the problem lies. It could even be those output stage transistors? I'm not a huge fan of those things... That amplifier could be a clone of a JLH (john Lindsay Hood) design or a Quad design, those two designs are all over eBay! And if that's the case, they were probably designed to run the T03 2N3055's which are much better for audio. John Audio Tec would fix this thing for sure. If all else checked out ok, I would replace the feedback resistor on the opamp to try and get more output out of it... But definitely check for clipped signal between the different stages! It might be a simple fix, the Chinese probably copied the original circuit design but swapped out the output transistors which the circuit was never designed for and couldn't work out why or didn't know why but figured that it's a famous design and people are just going to purchase it, they don't care... That's the jist of it... But please do a follow up on it, together we can do it!

@KissAnalog 3 года назад

Thanks for the great feedback! I know what you mean - I hate not to fix something, but this amp cost near 100 bucks. Also, I think you are right about the outputs that they need to be switched to the 2N3055s and that's just more bucks. And then even then, this design might just be a loser. BTW, John doesn't buy/review the more expensive amps that I do;) My wife would kill me if she knew how much I spent...;) I tried to find a schematic or more information, but all I can find is the description referring to this as a 'no feedback' amp. So, that could be a problem adding more gain to the input stage as it could make it go unstable. I'm confident that what this means is the output stage is a driver/buffer stage and that all the gain comes from the input stage. I think you are right that whoever filled the parts list might have made some value changes. I think I did find a comment on one of the sites that sold this listing parts that needed to be changed to get more power out. At the time I wasn't concerned about getting more than 20 Watts, and I hadn't purchased the amp boards yet. Now I can't find that information, and I have spent too much time looking. If I had the schematic I'd feel a lot more comfortable. The vendor offered to have me return it. I can't solder and remove parts to trace the circuit if I'm sending it back. So, do I eat the cost of this and what might be a dead end, or bail out? I have compared this board and parts (transistor count) to other designs that are on sale at various vendors, but I can't find anything that matches up. Either the front-end OpAmp or transistor count or mostly both, doesn't match up. I tried to show that it is the front end that is causing it to clip so early. I showed the regulation on the front end stage where the zener sets the voltage. And then, when I change the +/- Voltage rails from around 17 V all the way to 31 V, there's no change in the clipping level. This shows that the output is controlled by the input level. The way to fix it - without changing the gain stage is to let more voltage get to the OpAmp. It would be safe to let it go up near +/- 20 V. That would give a good 4 V higher peak, but still be woefully short of 20 Watts. Changing the feedback resistor around the OpAmp would be the more sure way to get higher gain. But, I tried to trace that part of the circuit, and I'd need to remove parts to see the trace work. Taking continuity measurements only got me so far. BTW, I'm sure that the transistors on the heatsink are the drive stage.

@PeterMilanovski 3 года назад

@@KissAnalog if that's the case, if you can send it back and get your money, that's what I would do, having no feedback to control distortion, its missing a potentiometer to either adjust the bias or mid point or DC offset makes it to difficult to make voltage change's... Just send it back... There's far better options out there, I have purchased class A amplifiers that came in a pair of two mono boards for $15Au and they had mid point and DC offset adjustment's to allow you to use them with the power supply you choose, they are only rated for 10W but because of their flexibility, you are only limited by the specs of the transistors (although they can be replaced with something better if needed), the size of heatsink and of course power supply capabilities... Also being two mono boards, they can be mounted on either side of an enclosure if you are using one of those that have heatsinks that run down either side... I realize that John only works with Amplifiers on the cheaper end of the scale but that's just what set's you apart from everyone else! It's a real shame that this amplifier didn't work out because at first glance it looks good but unfortunately it's not worth it... Send it back while you still can... Those 10W amplifiers that I mentioned earlier, they were able to rock my house, I have no complaints especially for the $15Au that I paid for them... I personally recommend getting a set if you ever come across them on eBay, they will have two multi turn potentiometers and a large blue capacitor in the middle of the board, well worth the money 💰..

@aurthorthing7403 3 года назад

I like having some extra headroom on my amplifier. I don't like pegging everything out just to get it to my preferred volume level.

@KissAnalog 3 года назад

I completely agree;)

@jesterraj 3 года назад

How about doin a review on the class d amp you bought the one with the built in fans....im intrested to see if it output is at the rated power.....

@KissAnalog 3 года назад

Thank you! I’m going to alternate projects and get that one back in the line up;)

@myelectronicsworld 3 года назад

This video has been overwritten by the 2nd video I believe.

@KissAnalog 3 года назад

Thank you!! I'm working on it now;) I really appreciate you!

@n2185x 3 года назад

Hi Eddie. Are there any published specifications for the amplifier? I have to wonder if the power delivery issue is specified at a particular frequency or frequency range. I was under the impression that lower frequencies require much more power delivery in order to achieve a given volume (which is why subwoofers use so much power compared with tweeters), so it wouldn't surprise me if the power figure is for a pure tone at the lowest frequency that the amplifier supports. Whaddya think?

@KissAnalog 3 года назад

Thanks for your feedback!

@johnshaw359 3 года назад

There is something wrong with that is there another connection for the power section?. The max voltage seems to be for the op amps, 17 volts seems kinda low for power amp rails. What's the idle power consumption etc. Are those really to3? outputs?. Can you work out what it actually is?

@MichaelBeeny 3 года назад

I think I agree John, more like power supply for the pre amp, probably a 5532/4 something like that. I don't think the regulators with those small sinks will handle the class A current. Plus WHY would you do that?

@KissAnalog 3 года назад

Great questions! You are right, this is the voltage for the rails of the OpAmps. That's what I meant to show probing the zener diode. I meant to explain that this regulation is for the input circuitry, and not for the power rails. I kind of joked that that would be too inefficient, even for Class A;) I think what the problem is, is that the gain of the OpAmp drives the final stage that has no gain, so when the input stage clips - it sends that to the output stage. I was trying to show that by demonstrating that it didn't matter what the plus and minus supplies were set to - form around +/- 17 V to +/- 31 Vdc. So I could correct that by increasing the gain of the OpAmp, and/or by increasing the zener diode range.

@KissAnalog 3 года назад

Thanks #Michael Beeny! What do you think of my response to #john shaw?

@nicoras8803 3 года назад

@@KissAnalog I don't think that you would get more than 8 or 9 watts from the class A amp. Increasing rail voltage just puts the output transistors at more risk of damage. Please check which output devices are used, and we can look up their SOA (Safe operating Area) in the data sheet. Coming from Chine these may be used (removed from another scrapped product) or even fake. Used is not so bad as it remains original. What I would say is that you should measure the total current of each output device, this is easily done by measuring the volt drop across the emitter resistors and calculating the current. This then would tell you what output power you could expect by applying P = I²R you won't get more regardless of increased supply. Also make sure that both transistors conduct the same current, else it is not class A but some other topology. This thing should be running F@$^&KING hot not even warm, I am predicting 50 degrees centigrade with even a large heat sink.

@JasonLeaman 3 года назад

Eddie, since the Chinese Amplifier was a fail, you should rip one of those TO3's out cut the top off and show people what a china faked transistor looks like ! :P

@KissAnalog 3 года назад

That would be a great idea. I don't think the problem I am having here (clipping) is due to the TO3s thought, it comes from the input stage. But, maybe the TO3s would fail with more power, so it would be nice to know if they really are real. However, the vendor agreed to accept the return, so I think I'm sending them back. I did also get 2 right channels and not a right and left.

@JasonLeaman 3 года назад

@@KissAnalog Build those Large white boards :P easy & very nice !

@reynolds087 3 года назад

Couldn't you replace the zener diodes with higher values for more headroom on the output?

@KissAnalog 3 года назад

Great question Josh! Yes, I think you can, and that would be probably the easiest step. I think you would still be limited to about 12 Watts without further improvements. I'll post a new video to explain.

@JasonLeaman 3 года назад

I think i sent you a few very nice amplifiers ! Them Green white Jean Hiraga Boards are easy to build and will do 60watts easy :) Sent you nice MJE output's too :)

@PeterMilanovski 3 года назад

The MJE output transistors are terrible for audio... When it comes to the classic T03's, the 2N3055's were used everywhere and were very good at it. Even the Chinese reproduction of them are good! That amplifier looks like a clone of an older design which was probably designed to be used with the 3055's, some person in china probably thought that it would be a good idea to add a buffer stage opamp and use what appears on paper to be a superior transistor but if the amplifier wasn't designed for them, it's not going to work... I have swapped out the 3055's for MJE's because I was reading in a forum about how good they are and everyone else was saying the same thing, I got some and tried it! It was terrible.. I would have had to put in a lot of work to get them to work... There's an old saying, just because you can, doesn't always mean that you should! That saying has never let me down..

@JasonLeaman 3 года назад

@@PeterMilanovski I would disagree with you 100% Chinese fakes = crappy performance AKA fire / Smoke. I sent Eddie some Jean Hiraga amplifier boards and some nice MJE transistors to build with. The PCB / Kit that Eddie is working on here is another perfect example of China cloned garbage that didn't work and results in wasted money ! PERIOD !

@PeterMilanovski 3 года назад

@@JasonLeaman if those boards that you sent Eddie were actually designed to work with the MJE's, then that's perfectly fine! The board's that Eddie is working with are definitely clones of something, could be a John Lindsay Hood design or another popular clone is a Quad 40 something... Whomever built this thing has decided to improve it without knowing what he was doing... I have used MJE's in lieu of the 2N3055's which the circuit was based on, expecting to get better performance and sound because everyone else on the forum claimed to be getting but that wasn't the case for me... I have built that cheap Chinese eBay Quasi Complimentary amplifier that a few RU-vidrs had a go at and got pretty good results with it and even was able to get claimed rated power but I had to increase the voltage to do so... Luckily the amplifier had the adjustment for bias and midpoint so that I can feed the higher voltage into it... The amplifier that Eddie is working with, needs to have its signals looked at between the stages to see where the clipping is happening, if it's only showing up at the output, then that's a clear indicator that the amplifier was designed to work with MJE's... I would then try different different T03's... Most notably the 2N3055's which is what it was originally designed for... The Chinese remake of the popular 2N3055 isn't as good as the original and I have seen fakes that had small signal transistor's inside, but the majority of them are okay... I have purchased heaps of them at the cheapest price available from eBay china and all that I have used thus far have been good, I always make a small purchase, test them when I get them, if they pass, I get heaps from the same seller... I have read the books by Sloan and John Lindsay Hood and even Nelson Pass, the amount of output transistor's that these guys go through to get the design perfect is insane! I have a huge respect for them, and their designs are still standing the test of time, that's why you can find clones everywhere... We shall see what Eddie comes up with when he gets the amplifier you have sent him, honestly I have never heard of it so I will be keen to see it's performance, especially with the MJE's, I have a box full of them waiting for a home.... Incidentally, just a thought! You weren't the same person who sent an amplifier kit with a set of MJE's to John Audio Tec's channel? That was a great video because it shows exactly what I'm trying to say...

@JasonLeaman 3 года назад

@@PeterMilanovski If you want a pair of boards send me an email ill send you a pair :P PM me through my channel

@PeterMilanovski 3 года назад

@@JasonLeaman no worries! I will keep it in mind, I already have more amplifiers than I know what to do with! But I'm always looking for something that looks and sounds good! I will have a good look at them when Eddie posts a video on them...

@richardgray8593 3 года назад

I might order a couple just so I can answer the question, "What kinda amps are you using? Marantz? McIntosh? Technics?" Nah, man. WunHungLo.

@KissAnalog 3 года назад

LOL This amp is hanging a bit too low;)

@ats89117 3 года назад

Your amp doesn't go to 11...

@KissAnalog 3 года назад

No it doesn't go to 11 Watts. Do you have one like this?

@RESISTAGE 3 года назад

silly. it's 20 Chinese watt. small u know.

@KissAnalog 3 года назад

LOL, I guess you are right;)

@ats89117 3 года назад

My comment was a reference to this jewel from 'Spinal Tap'. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-uMSV4OteqBE.html I don't have one, but it does look nice and I might get one. Like you, I am always amazed when people regulate voltages on power amplifiers, unless they need to be regulated to prevent destruction of components...

@KissAnalog 3 года назад

LOL Thanks for the clip;)

@Hungry_Hunter 3 года назад

Ditch those big lumps of metal around your wrists and could you please not say "What's Up" at the start of your video. Strewth.

@KissAnalog 3 года назад

Sorry I offend you. Have a nice day. Too bad you can’t focus on the content instead of a braclet I wear to remember a vacation my daughter and I took together.