20W Class A - Power Tested THD & Bode Plot

Подписаться 31 тыс.

Просмотров 2,3 тыс.

50% 1

In this video I'll show the Bode Plot at 20 Watts and 1 Watt for the #20 Watt Class-A amplifier. It is titled #20 Watt Class-A Power Amplifier - Power Tested Bode Plot & THD. I'll also show THD at various frequencies and power levels. I'll start with showing the temperature rise at 1 Watt and 20 Watts. #20WattClassA #Bodeplot #THD #GWInstek
Class A Power Amplifier Playlist: • Class A Power Amplifiers
Link to Amp Chassis (very nice): ebay.us/MI5bYJ
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
Zener Diodes: amzn.to/3qlKoYH
Wire clamps: Wago assortment: amzn.to/3qkY4mQ
Keadic assortment: amzn.to/2N80vKT
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 played here:
Ravenface; Tyrants and Kings
• Ravenface - Tyrants an...
Credits:
► Ravenface:
ITUNES: www.youtube.co...
SPOTIFY: www.youtube.co...
FACEBOOK: /
RU-vid: / ravenfac...
► Free Music Download Channel
• www.youtube.co...

Опубликовано:

13 сен 2024

Ссылка:

Скачать:

Готовим ссылку...

Добавить в:

Мой плейлист

Посмотреть позже

Комментарии : 56

@nicoras8803 3 года назад

I like your pre-qualifications testing, it sure helps in finalising your product at least most of the specifications is known and you can design the rest starting off with less guessing - keep up the good work.

@KissAnalog 3 года назад

Thank you Nico! Let me know how you think as I move along - I really appreciate your input!

@nicoras8803 3 года назад

Let's follow you finishing the amp completely, it would make for an interesting build!

@KissAnalog 3 года назад

Thank you! Let me know what you think as we go forward;)

@amplidude101 3 года назад

Once again a very good video, I do like that thermo couple, I might have to find one myself. Another thing, the load is not realistic, its only resistive, with a little inductance, it needs a 1 or 2 uf capacitor across, that really stresses the amp more, and I also like to see a fft of the harmonics distortion, in my class a build I aim for second harmonics as I find them more ear pleasing. I use a soundcard and arta for those readings, and a autoranger that keeps a steady input to soundcard line in. I have watched several of your videos and feel I need to give a little back, i will set up as a patreon so you can continue making those great videos, and hope more will follow. Ps. I would put a relay with a 555 timer across that thermistor so theres no loss, let the relay close after a few seconds

@KissAnalog 3 года назад

Great input - thank you!

@pa3eka 3 года назад

Hi eddy long time ago i see you My wife died in November and my life is changed very much after 47 years merry her Succes Eddy

@nicoras8803 3 года назад

Sorry to hear it, it is bad to lose a life long partner. My father passed 13 years ago an mom never recovered from it.

@KissAnalog 3 года назад

I'm so sorry to hear this. I hope you are OK and I wish you my best. I can say that you are a lucky man to have a partner for 47 years, that is really amazing! But, that makes it all the more sad too. We have missed you here, and I am honored that you came here to share this. Hope we can help you with this channel and provide something interesting to watch.

@freelanzr 3 года назад

Really enjoying this channel... Thanks!

@JasonLeaman 3 года назад

It's a good one hey !

@KissAnalog 3 года назад

Thanks so much!!

@versace885 3 года назад

Hi Eddie, as usual another great video. Thank you

@KissAnalog 3 года назад

So nice of you

@amplidude101 3 года назад

Hi nico, yes let's see how it goes, I have a bad feeling, the toroidal looks to small, i would agree on smps, or at least a crc clc linear power supply, but the voltage drop would be substantial, let's wait and see

@nicoras8803 3 года назад

That transformer by the size of it looks about 100VA may 120VA with a little sweat, cannot imagine that the regulation is going to help much SMPS would definitely be the answer.

@KissAnalog 3 года назад

Thanks Guys for the questions. I'll do a follow up showing the final build, but I did finally get more power and did go to the larger transformer;)

@ianhaylock7409 3 года назад

Hi, nice video. If you keep this up, I'll have to build one of these amps as well. I think the toroid should be about 400va for a 20W class A amp, so your's look a bit small. Not sure if your case heatsinks will be big enough, though you could always strap a couple of fans to them. I did this on my Aleph 5 amp, and dropped the heatsink temperature by 10C.

@KissAnalog 3 года назад

Thanks Ian! I think you might be right;)

@nicoras8803 3 года назад

That is pretty good gain and phase response. Remember, you need a lot of capacitors on a class A to reduce the ripple as it draws full current all the time. We would love a schematic of the amp. Off the cuff it seems a pretty good and stable design. I would use a Capacitance multiplier to keep the ripple out of the amplifier, else you may be disappointed at it humming.

@JasonLeaman 3 года назад

a CRC psu will help with Ripple, he doesn't need "TONS" of capacitance.

@KissAnalog 3 года назад

I think I have the schematic traced out and ready to show in a video very soon;)

@TRONMAGNUM2099 3 года назад

Good video. looking forward to the finished product. I watched a video where the host said it takes more current to drive an amp at lower frequencies than higher. Like 40Hz vs 1Khz. I'd be interested in hearing your thoughts on this.

@KissAnalog 3 года назад

Thanks - that's a great question. It is interesting as the frequency gets lower it is closer to DC so less time to charge capacitors. But on the other hand, as it gets lower than 60 Hz (or 50 Hz for other parts of the world) the line power has more pulses to charge the power supply rails. It really doesn't matter that much if it is continuous power, but with real music it does. This is a great subject and I'll try to demonstrate this.

@wahng9552 3 года назад

Great video as usual, thanks. You show the phase is -15 degrees on the low and high end, is the goal to get as close to zero degrees across the whole range ? Trying to understand what less/more phase shift does to the audio.

@KissAnalog 3 года назад

Great question! Thank you! I think many amps have more phase shift because 0they roll off closer to 20 K which the phase rose off even sooner than the gain. And at the low end capacitor coupled inputs will have more phase shift as well. Yes, I think it would be ide to keep it flat. I don’t know how keen the ear is on phase shift.

@timothygrupp 3 года назад

Type K TCs and thermal epoxy with a datalogger are my favorite way to characterize temperature v time performance. The amp is certainly a good performer--corner cases will generally find the areas of most concern. My concern with a 20W amp is that I most likely would be using it for bi-amping HFs, and the testing seems to show that the worst case performance of this amp is distortion at high frequencies. Interested to see if getting thermal conditions stable would improve that performance.

@nicoras8803 3 года назад

How much THD would you expect to hear at 20kHz since the first harmonic is at 40 kHz and your hearing threshold (if you were a little at say 15 years old) drops of at about >40 dB/Oct. Thus a measured THD of -60 dB would be -100 dB to your ears, well above the noise floor in your room. I could approximate that to the noise an ant makes doing a tap dance in a pair of slippers 100 yards away. :)

@KissAnalog 3 года назад

Yes Tim, I agree! I like to have thermal couples placed in various locations so I can watch things in real-time. I wanted to move the program the heat seat to see how the temperatures spread and how well the thermal coupling was working.

@trollobite1629 2 года назад

@@nicoras8803 Excellent point but if you're addressing a member of the *golden ear* brigade you're wasting your time 👍

@BjornV78 3 года назад

9:50 Keep in mind, that the final mounting direction of the board will be different then the way it is placed on the bench, so this plays a big role in heat dissipation.

@KissAnalog 3 года назад

Thank you that is a great comment!

@nicoras8803 3 года назад

It is not a rule of thumb, just look up the temperature rise per degree centigrade. Now a Class A am is about 20% efficient, thus the heat sink must be capable of emitting the heat into the environment. A rule of my thumb would be that take an environmental temperature at 20degrees centigrade above what the hottest day is where it will be applied, then calculate what size heat sink should do the rick. A class A amp always run at maximum temperature regardless of its output. The bias current flows continuously.

@KissAnalog 3 года назад

Thanks Nico!

@JasonLeaman 3 года назад

I think that Heatsink is going to be to small. Good video Bud ! Why not use the Purple CRC psu board i sent for this ? install 6 x 10k caps 4 mur60 fred's then do the crc math for the ripple noise. That could be a good next video btw :)

@KissAnalog 3 года назад

Thanks and I think you might be right, but I wonder if playing real music versus constant power it will be OK? I'll build those purple boards that you gave me - I think that will be a fun project!

@JasonLeaman 3 года назад

@@KissAnalog Class A amps get hot the second they turn on, unless you have a fan to keep the heatsink cool, then might have an issue !

@nicoras8803 3 года назад

I think your friend would be very happy if you would get the power supply nice and clean. In fact when you hear it properly setup you may just keep it. Class A sounds completely different to any other topology and I only design class A amps for the past 25 years. It has a character of its own, few other topologies can't even dream to touch it, only downfall is its heat output (efficiency as you call it). Only the best speakers should be utilized with a well-designed class and that seems to be the case here. Keep it, give your friend a class D, you would appreciate the class A more. In my humble opinion I would use a switch mode power supply on the amp, not a toroidal, you will pull your hair out trying to get rid of hum. Switch mode are specifically designed to pass high current continuous, there are many available on eBay, look for a 27-30V 5 or 10 amp, (they normally have +-5% adjustment available) and use two to configure the +/- power supply and say 4700uF -10 000uF 35VDC capacitors on the rails.Your newly acquired amp will have little that can touch it. 20 watt is more than enough even in a large listening environment, importance is an equally good set of speakers, here the Klipsch Heresy comes to mind if you like loud rock with plenty of punch. If you can lay your hands on a pair of KEF Concertos, that pops onto eBay now and then, would also be a great speaker for this kind of amp if you like more warmth and easy listening.

@amplidude101 3 года назад

Most smps dont like extra capacitance or indicators, some become unstable and enter fault mode, trail and error I guess.

@nicoras8803 3 года назад

@@amplidude101 I have never had the problem with well designed SMPS like Meanwell, they have a low startup specifically for this application. I think you may be referring to an LED power supply, which I assume do not have soft start. Besides one can place an NTC in series with the caps to cause a soft start. 10 amp NTC will probably cast $0.50

@KissAnalog 3 года назад

I'll do a SMPS design for another project so we can compare the two. Great feedback from everyone here on this comment;)

@nicoras8803 3 года назад

THD at 20kHz is of little importance since the first harmonic is 40kHz, above that of human hearing.

@KissAnalog 3 года назад

So true Nico! This Amp is so flat for high freq that I just ran the test;) I need to do a video that explains this. Thank you!

@jamesaguirre853 3 года назад

Eddie do you have a link for the Amp Chassis case you are using, I like it.

@KissAnalog 3 года назад

Thanks James! Here's the link to the case: ebay.us/MI5bYJ

@carloverzeletti6521 3 года назад

My rule of thumb. More heatsink alloy the better... Bahahaa

@KissAnalog 3 года назад

LOL I have to agree with you;)

@johnsweda2999 3 года назад

Hi you never know! third time lucky!.? what about using a class D as the power supply driving the class A what is the cons and benefits I've heard if you split the mica into 3 parts you get a better thermal coupling. what about if it was on a ceramic heatsink plate then you could bolt transistor directly

@KissAnalog 3 года назад

I could use to help reduce the dissipation in the Power Supply section. But, for this class say I think I want to go old school all the way with the linear Power Supply. Later, now I want to be able to switch her and compare the difference. I’ve never heard of that technique about splitting the mica up. Mica is somewhat brittle and you do not want it thicker where it broke or thinner where it has not been compromised. So I don’t know about cutting or breaking it in thirds. Also, I don’t know if the thermal paste s a better thermal transfer then the Mica.

@johnsweda2999 3 года назад

@@KissAnalog I was just talking generically about the class D amplifier as the power supply, but you're going to do something in the future on that that would be interesting considering it gives a very clean analogue waveform its is a regenerator in itself in the power supply I would have thought should work well. Yes you might be right with the Mica I don't know splitting it twice should be alright, I don't know what thermal properties Mica has. Shouldn't you clean them back of the transistors before placing them on I mean rubbing them with wet and dry paper on a flat surface to get them as smooth and shiny as possible not designed engineer to be flat and what about the coating on the heat shield restricts thermal coupling and has machine marks what would reduce the thermal efficiency

@johnshaw359 3 года назад

Yeah, a class A amp will cool down as you drive it harder as some of the output current is dissipated in the load/speaker. Do you have any additional rail capacitance that you could do a comparison test?

@KissAnalog 3 года назад

Thanks John! Sounds right;) I will do this comparison as I start to finish the build - thank you. Any further input is always appreciated;)

@nicoras8803 3 года назад

Why not just fit it to the heat sink than trying tom break it.

@KissAnalog 3 года назад

Great question! ;) I like to see what each element of the thermal chain looks like or is capable of, so we know how much we need to add. It also helps those who are newer to amp designs to understand the heat path and what is needed.

@amplidude101 3 года назад

As I said in a earlier post, I dont like to just receive and give nothing back, do you have a PayPal account eddie? I searched name and mail , nothing showed up.

@KissAnalog 3 года назад

Thanks Thomas - that is very kind of you!! I'm on PayPal at KissAnalog@gmail.com, or at Patreon; Patreon.com/KissAnalog