First of all I thank you for making so many informative videos till now. No channel I find videos with so much information about every tiny things like yours. All others mostly do the hardware fittings, drilling and all that but your videos have lots of things to learn for beginners and hobbyists. Thanks again and great going!!🙂
Still using that chip for over 15 years now as a headphone amp and it has been very good. Runs fine on a small 250mA transformer for my 32ohm over ears. Quiet and clean with a flat response but I do have to limit input to very levels to work around the fixed high gain. This chip used to be the popular choice of budget desktop speaker manufacturers, before the advent of class D chips
Hello John, A very interesting and informative video, you definitely know how to build them right. A favorite channel for many years now, Thank you for all you do providing quality content. I wish you and your family all the best in '21, stay safe, stay at the bench, C.
Well, I for one, was not in a big hurry just to get those numbers. I'm so glad you took the time to explain the feedback setup. I've seen these configured in a few different ways, it was nice to see an explanation on what to do. (For novices) (No wonder my setup on my little breadboard didn't work) I think these are my favorite chip amps, and the little brother, the tda2822m. Sadly, I don't have many of those, but do have a few clones. (KA2209) for example. I very much appreciate the time and work you put into this video, John. Thank you
Ah yes one of my favorite chip amps. my PC speakers, Teinuro TL-M2102C which ive ran for 6 or 7 years now have a pair of those chips. when i was 11 or 12 i had one of those generic gaming chairs with the speakers on the side and its amp was a 2025B. i still have the amp board from it lol
One easy way to reduce the output noise with an amplifier like this is to add an attenuator at the input after the signal source. This will do a few things for you: it will effectively reduce the gain, reduce noise from the source, and allow for impedance matching.
Hi John. Irrelevant to this video: I have a suggestion if you can or want. When making led bulb videos it would be quite interesting to check the driver/circuit for emi filter presence. One of the problems the now widespread use of led bulbs has caused is increased electromagnetic interference and radio frequency interference. I think it's important to know whether an led bulb we are about to buy or already own has filtering or not.
It was because of John' chip amp tests, that I had to go re visit my collection of chip amps I salvaged from cheap boomboxes, and computer speakers. Turns out, I have quite a few of these. Just remember, use a higher value cap on the input, and output, if you want the lower frequency range to come through better. (Stereo set up) these chips are way better then what they were mainly used for.
I Need Some Boards Just That Size. I passed up on a pallet of boards all different sizes and types. Had no place to store them so had to leave them for another person to claim. Anyway great analysis I have a couple of these and was wanting to maybe use for mics Wont know till I try right. 👍
13:52 Given that the extra resistor (R3, say) is in series with the 50Ω resistor, shouldn't the calc be R1/(R2 + R3) + 1 = V, where R1 =10kΩ and R2=50Ω; that would give R3 = R1/(V-1)-R2, i.e. R3 = 111Ω.
I personally prefer single ended amplifiers over bridged amplifiers. I don't understand the gain limitation to 36 dB. The more negative feedback you allow the more stable a non-inverting AB amplifier works. I think, there is no problem to reduce the gain down to 50 or even 20 or 10. Relating the snubber network: you don't need two for a bridged amplifier. It works simple also with a single snubber network between both amplifier outputs.
The more feedback you apply, the the less phase margin there is. This is why they caution you on the datasheet to use additional compensation when setting the gain below a certain point to avoid instability.
@@JohnAudioTech I think, with a "real" snubber network you can avoid oscillations at higher frequencies. This helps a lot for lowering the gain. So you can probably go down to 26 dB. For bridge configuration I also use a single snubber network between the speaker connections in order to avoid to draw higher currents at higher frequencies across the ground which could influence the input signal with positive feedback.
what about building a Class D stereo amplifier based on a NE556 and using a NE555 as a clock generator and using a high power driver to drive the speakers via high pass filters and two TLO81 op amplifiers for use as the error amps driving the CV pin on the modulators.
Hello and thak you for your work! Have one from an nortek 2.1 sistem sound extraordinary with a variety of speakers, the problem is that I cannot find and I dont't kwow where to find them, I need them so much to power more speakers/subwofers, they soun great, I have and denon 7.2 receiver, sound trash compared to this small amp + yamaha/mica, etc speakers and 100W passive kenwood subwoofer, please tell do you know other sistems that include this chip? old 2.0, 2.1 amps, just need to put a good suply and a cpu cooler radiator, without vent and the magis will happen. Thank you in advance!
Hi John, In bridge mode where did you connect the earth wire from the scope? Normally not an issue on a standard amplifier but with bridge both outputs are floating and the speaker simply goes between these outputs.
I am completely ignorant when it comes to this tech stuff. I envy you brain. I need some help with a project I am thinking about and I believe the LM 1875 is what I need to start with. I would like to discuss more in detail if you are willing to share.
I would start with an lm386. The Lm1875 requires a heat sink, and is intended for dual supply operation. ( the data sheet has the circuit for single supply operation.) Also the lm1875 minimum opperating voltage is higher.
Do you know of any circuit to "improve" vintage record players with crystal cartridge because if you hook up the crystal cartridge to a solid state amp all bass is gone and it sound horrible. So I would need a pre amp that has few megaohms input Impidance.
Greetings, i recently had a JBL 305p MK2 that was working perfect for 2 days then recently started playing very very low. Sent it to a technician and was told It was the Audio Output IC chip that has gone bad, Any advice to where i can possibly buy another one for the JBL 305p MK2? Would really love your advice on to what i should do from here, JBL customer support was not helpful at all. I believe The chip is ST8500
Hello John. I need your advice. Iam building a 2.1 sound system, which is using TDA7265 for stereo and TDA7294 in bridge for bass. The total wattage will be 250watts. Can you please tell me that what value of filter caps shall i use in power supply. I will be using 24-0-24 5amp transformer. I saw a video which was advising to use 1000uf per 10watts of power, so accordingly it makes out 250x(1000/10)=25000uf. I want your advice on this. Is this concept correct or lower values will also work ? 🐱🐱
Hi John What do you think is better, MOSFET or transistor output stage and why? Also Ive always wanted to build an amp that at low volume operates in class A mode and then moves in to class AB or rather B at higher output, I have repaired amps that do this like for example a Marantz PM94 which has a MOSFET and Transistor output stage and swings between the two classes based on output levels. Ive had a few ideas on how to do this but i'd be interested in any thoughts u have on it. The marantz uses optocouplers and a op-amp for monitoring, it pulls the biasing and switches the class at higher volumes and I was going to base my design on this method. Great videos BTW!
Each transistor type has its advantages. Some EE amp designers don't like MOSFET amps but Bob Cordell gives good points and designs in his power amp design book on both types. All class AB amps operate in class A for at least a few milliwatts due to the bias. Of course there are more complicated biasing schemes that are supposed to improve the sound. If an ordinary class AB amplifier can produce less than .01% THD at 1 watt, I see no sane reason to complicate the circuit with more parts.
I am curious about that distortion measurement, there is fundamental, 3rd harmonic injected signal along with that there was a signal very left to the screen. What that indicates? Presense of zero frequency output (DC voltage) with this amplifier?
I can't answer your question, but the response you refer to as 3rd harmonic I believe is at 4.5KHz to avoid being on a 1kHz harmonic and is set to 1% of the fundamental to give some scale to the harmonics displayed.
When I tried to calculate the gain of the amplifier using my mobile phone calculator I faced the following problems - 1. On tapping the log button to convert 200 (gain) to decimal it returned 200 log( instead of decimal value 2. If I put 20 inside the bracket, it returns even larger value as gain. But if I tap log button before and then enter 200 as gain then it's returning correct decimal value and multiplying it by 20 gives 46db which is correct gain in db. What could be the reason ? Is it the phone calculator behaving like this or there's some other way out ?
Sounds like the math logic on the phone is how you would write it out. I have a calculator that I enter 20log200= and it shows 46.02... easier than standard calculator logic.
Now I have some questions - 1. Can I use a socket for this IC ? 2. What type of heatsink to be used with this chip and is it available readily or have to be made out of junk ? 3. Can we reduce the gain in bridge mode too to 36db ? 4. Can we reduce the gain of LA4440 IC in same way like you did here for this chip ?
1. Don't use a socket. The chip needs a soldered low resistance connection for the ground/heat sink pins. 2. "U" shaped heat sink with tabs that are next to the heat sink pins that solder into the board. Hard to describe without a diagram. 3. See schematic in video. Each amplifier of the bridge is ~36dB but, due to the double voltage swing, the actual gain would be 42dB. You can reduce the signal further using a resistor divider on the input. 4. Looks like that chip uses a similar scheme. You'd have to check the datasheet for a minimum gain setting.
@@JohnAudioTech 1. If Negative feedback capacitor value is increased or decreased, what will be the effect ? 2. If zobel network capacitor value is increased or decreased, what effect will it make ?
@@amitghosh6966 1. decreasing it can cause the gain to drop at lower frequencies. Increasing, the opposite effect. It should be sized to keep the gain flat in the audible spectrum.
@@JohnAudioTech I assembled an amplifier circuit using Ta8210 chip on veroboard using the same components as on datasheet but on powering up the circuit there's motorboating sound from the speaker even with no input signal. I noticed the negative feedback pin has a 47uF capacitor according to datasheet but I suspect it's making the gain too higher. The datasheet says the typical gain is 50db. 1. Could it be the reason for the motorboating ? 2. If so How can I reduce the gain of the circuit ? 3. If possible, please do a video on this chip Ta8210 for better understanding about this chip for everyone. Thanks in advance
How did you set up fft on your scope. I got my first scope (siglent sds 1202X-E) But I still didn't figure out how to set up fft. Is there some tutorial or something?
disapoint .. i have this chip TEA2025B on a 2,1 speakers system and sound amazing for them power and heatsink what they have. One chip is on bridge mode to subwoofer 6 ohm, and 2st chip are in stereo mode 4 ohm speakers . i change transformer from 9v 1.1A to smps 12v 2.5A. i dont measure power on satelites speakers , but on subwoofer i have max 10v on output. at 7,5 - 8V is not even 0,5% distorsion and nothing.something wrong on your design or power supply or heatsink is needed
So what's the problem? After I got the circuit working properly, it is a good amplifier. I see no distortion above ~.3% in bridged mode which is great for this IC. With around 1.1 amp rms max output current, I would be leary of pushing it too hard with the reactive load of an 8 ohm speaker at 12 volts supply.
@@bernardmarx6705 The purposy of this is knowledge. We get to aquire knowledge. For example, I bet that many guitar players would love to own an overdrive pedal built with this chip because of its soft clipping, I'm sure they would pay a lot for that.
First of all I thank you for making so many informative videos till now. No channel I find videos with so much information about every tiny things like yours. All others mostly do the hardware fittings, drilling and all that but your videos have lots of things to learn for beginners and hobbyists. Thanks again and great going!!🙂
Really good video. The part about adjusting the gain is very educational.
I notice the clipping after try it. What chip better Substitute ?
Thanks for the shoutout John!! And yet again another great video! This is why your channel is one of my favorites.
Which video is it?
well, here's the well balanced ''AB amp'' composer!! I'm also finding some hang-outs!! now if I can just ''learn''?
Just found your channel and now I find you here ! now I'm subbed to 2 great audio channels...cheers!
John you can go on about the functionality of the amp components as long as you want, as far as I'm concerned.
Still using that chip for over 15 years now as a headphone amp and it has been very good. Runs fine on a small 250mA transformer for my 32ohm over ears. Quiet and clean with a flat response but I do have to limit input to very levels to work around the fixed high gain. This chip used to be the popular choice of budget desktop speaker manufacturers, before the advent of class D chips
Hello John, A very interesting and informative video, you definitely know how to build them right. A favorite channel for many years now, Thank you for all you do providing quality content. I wish you and your family all the best in '21, stay safe, stay at the bench, C.
Well, I for one, was not in a big hurry just to get those numbers. I'm so glad you took the time to explain the feedback setup. I've seen these configured in a few different ways, it was nice to see an explanation on what to do. (For novices)
(No wonder my setup on my little breadboard didn't work)
I think these are my favorite chip amps, and the little brother, the tda2822m. Sadly, I don't have many of those, but do have a few clones. (KA2209) for example.
I very much appreciate the time and work you put into this video, John. Thank you
Thanks for watching!
Excelent as always !! ⭐⭐⭐⭐⭐
Ah yes one of my favorite chip amps. my PC speakers, Teinuro TL-M2102C
which ive ran for 6 or 7 years now have a pair of those chips. when i was 11 or 12 i had one of those generic gaming chairs with the speakers on the side and its amp was a 2025B. i still have the amp board from it lol
lol a chair with built in speakers
@@windshield11 right lmfao the mid 2000s were a fun time in the gaming scene
One easy way to reduce the output noise with an amplifier like this is to add an attenuator at the input after the signal source. This will do a few things for you: it will effectively reduce the gain, reduce noise from the source, and allow for impedance matching.
Hi John. Irrelevant to this video: I have a suggestion if you can or want. When making led bulb videos it would be quite interesting to check the driver/circuit for emi filter presence. One of the problems the now widespread use of led bulbs has caused is increased electromagnetic interference and radio frequency interference. I think it's important to know whether an led bulb we are about to buy or already own has filtering or not.
I do have a 12 volt LED bulb that cuts out my favorite oldies FM station when I turn it on. I might investigate.
Very cool ! I have a couple of these and this will motivate me to build an amp with them . Thanks !
Is very good chip amp. test and you will se..
@@GeoBass-89 Will do . Thank you
It was because of John' chip amp tests, that I had to go re visit my collection of chip amps I salvaged from cheap boomboxes, and computer speakers. Turns out, I have quite a few of these. Just remember, use a higher value cap on the input, and output, if you want the lower frequency range to come through better. (Stereo set up) these chips are way better then what they were mainly used for.
I Need Some Boards Just That Size. I passed up on a pallet of boards all different sizes and types. Had no place to store them so had to leave them for another person to claim.
Anyway great analysis I have a couple of these and was wanting to maybe use for mics Wont know till I try right. 👍
I love sound of 2025, bridge mode is so powerful 👍
13:52 Given that the extra resistor (R3, say) is in series with the 50Ω resistor, shouldn't the calc be R1/(R2 + R3) + 1 = V, where R1 =10kΩ and R2=50Ω; that would give R3 = R1/(V-1)-R2, i.e. R3 = 111Ω.
Yes. I commented in the text that I left out the +1 in the calculation. In either case, the next lowest common resistor value is 100 ohms.
@@JohnAudioTech Agreed.
Hi jhon!
Can you reach us about thermal protection circuits?,
Maybe adding thermal protection to one of your discrete amplifiers :)
Thanks for Great nice information alwage
I like the EEV Blog multimeter, I subscribe to Dave's channel too, he's a very smart engineer, small doses tho lol 🤔best regards
Kevin
I personally prefer single ended amplifiers over bridged amplifiers. I don't understand the gain limitation to 36 dB. The more negative feedback you allow the more stable a non-inverting AB amplifier works. I think, there is no problem to reduce the gain down to 50 or even 20 or 10. Relating the snubber network: you don't need two for a bridged amplifier. It works simple also with a single snubber network between both amplifier outputs.
The more feedback you apply, the the less phase margin there is. This is why they caution you on the datasheet to use additional compensation when setting the gain below a certain point to avoid instability.
@@JohnAudioTech I think, with a "real" snubber network you can avoid oscillations at higher frequencies. This helps a lot for lowering the gain. So you can probably go down to 26 dB. For bridge configuration I also use a single snubber network between the speaker connections in order to avoid to draw higher currents at higher frequencies across the ground which could influence the input signal with positive feedback.
what about building a Class D stereo amplifier based on a NE556 and using a NE555 as a clock generator and using a high power driver to drive the speakers via high pass filters and two TLO81 op amplifiers for use as the error amps driving the CV pin on the modulators.
Hello and thak you for your work! Have one from an nortek 2.1 sistem sound extraordinary with a variety of speakers, the problem is that I cannot find and I dont't kwow where to find them, I need them so much to power more speakers/subwofers, they soun great, I have and denon 7.2 receiver, sound trash compared to this small amp + yamaha/mica, etc speakers and 100W passive kenwood subwoofer, please tell do you know other sistems that include this chip? old 2.0, 2.1 amps, just need to put a good suply and a cpu cooler radiator, without vent and the magis will happen. Thank you in advance!
Hi John, In bridge mode where did you connect the earth wire from the scope? Normally not an issue on a standard amplifier but with bridge both outputs are floating and the speaker simply goes between these outputs.
My signal source and power supply are floating.
I am completely ignorant when it comes to this tech stuff. I envy you brain. I need some help with a project I am thinking about and I believe the LM 1875 is what I need to start with. I would like to discuss more in detail if you are willing to share.
I would start with an lm386. The Lm1875 requires a heat sink, and is intended for dual supply operation. ( the data sheet has the circuit for single supply operation.) Also the lm1875 minimum opperating voltage is higher.
Yay Snickers 😸
Are these chips anything to do with TDA? Since TEA and TDA are very similar names.
ST microelectronics (SGS back in the day) normally used the TDA prefix for chip amps, but a few were TEA. No idea why.
Do you know of any circuit to "improve" vintage record players with crystal cartridge because if you hook up the crystal cartridge to a solid state amp all bass is gone and it sound horrible.
So I would need a pre amp that has few megaohms input Impidance.
You pretty much called it. Any high impedance preamp, such as a FET input circuit or JFET opamp is the ticket.
@@JohnAudioTech Thanks. Do you have any circuit that you recommend
I built a "Pete's mosfet preamp circuit" and it works pretty good for such a simple circuit.
Suscribed!
Greetings, i recently had a JBL 305p MK2 that was working perfect for 2 days then recently started playing very very low. Sent it to a technician and was told It was the Audio Output IC chip that has gone bad, Any advice to where i can possibly buy another one for the JBL 305p MK2? Would really love your advice on to what i should do from here, JBL customer support was not helpful at all. I believe The chip is ST8500
Hello John. I need your advice. Iam building a 2.1 sound system, which is using TDA7265 for stereo and TDA7294 in bridge for bass. The total wattage will be 250watts. Can you please tell me that what value of filter caps shall i use in power supply. I will be using 24-0-24 5amp transformer. I saw a video which was advising to use 1000uf per 10watts of power, so accordingly it makes out 250x(1000/10)=25000uf. I want your advice on this. Is this concept correct or lower values will also work ? 🐱🐱
Hi John What do you think is better, MOSFET or transistor output stage and why? Also Ive always wanted to build an amp that at low volume operates in class A mode and then moves in to class AB or rather B at higher output, I have repaired amps that do this like for example a Marantz PM94 which has a MOSFET and Transistor output stage and swings between the two classes based on output levels. Ive had a few ideas on how to do this but i'd be interested in any thoughts u have on it. The marantz uses optocouplers and a op-amp for monitoring, it pulls the biasing and switches the class at higher volumes and I was going to base my design on this method. Great videos BTW!
Each transistor type has its advantages. Some EE amp designers don't like MOSFET amps but Bob Cordell gives good points and designs in his power amp design book on both types.
All class AB amps operate in class A for at least a few milliwatts due to the bias. Of course there are more complicated biasing schemes that are supposed to improve the sound. If an ordinary class AB amplifier can produce less than .01% THD at 1 watt, I see no sane reason to complicate the circuit with more parts.
You saw the hard clipping at the top because you clipped on your scope!
No. That was the amp clipping. If it were the scope, the signal peak goes off the screen (no flat line visible)
@@JohnAudioTech Well, my Rigol scope will definitely has a horizontal line displayed if the vertical range / position is off screen.
I am curious about that distortion measurement, there is fundamental, 3rd harmonic injected signal along with that there was a signal very left to the screen. What that indicates? Presense of zero frequency output (DC voltage) with this amplifier?
I can't answer your question, but the response you refer to as 3rd harmonic I believe is at 4.5KHz to avoid being on a 1kHz harmonic and is set to 1% of the fundamental to give some scale to the harmonics displayed.
@@twotone3070 thank you 👍
Can I use this circuit to design a hearing aid?
When I tried to calculate the gain of the amplifier using my mobile phone calculator I faced the following problems -
1. On tapping the log button to convert 200 (gain) to decimal it returned 200 log( instead of decimal value
2. If I put 20 inside the bracket, it returns even larger value as gain.
But if I tap log button before and then enter 200 as gain then it's returning correct decimal value and multiplying it by 20 gives 46db which is correct gain in db. What could be the reason ? Is it the phone calculator behaving like this or there's some other way out ?
Sounds like the math logic on the phone is how you would write it out. I have a calculator that I enter 20log200= and it shows 46.02... easier than standard calculator logic.
Now I have some questions -
1. Can I use a socket for this IC ?
2. What type of heatsink to be used with this chip and is it available readily or have to be made out of junk ?
3. Can we reduce the gain in bridge mode too to 36db ?
4. Can we reduce the gain of LA4440 IC in same way like you did here for this chip ?
1. Don't use a socket. The chip needs a soldered low resistance connection for the ground/heat sink pins.
2. "U" shaped heat sink with tabs that are next to the heat sink pins that solder into the board. Hard to describe without a diagram.
3. See schematic in video. Each amplifier of the bridge is ~36dB but, due to the double voltage swing, the actual gain would be 42dB. You can reduce the signal further using a resistor divider on the input.
4. Looks like that chip uses a similar scheme. You'd have to check the datasheet for a minimum gain setting.
@@JohnAudioTech 1. If Negative feedback capacitor value is increased or decreased, what will be the effect ?
2. If zobel network capacitor value is increased or decreased, what effect will it make ?
@@amitghosh6966 1. decreasing it can cause the gain to drop at lower frequencies. Increasing, the opposite effect. It should be sized to keep the gain flat in the audible spectrum.
@@JohnAudioTech I assembled an amplifier circuit using Ta8210 chip on veroboard using the same components as on datasheet but on powering up the circuit there's motorboating sound from the speaker even with no input signal. I noticed the negative feedback pin has a 47uF capacitor according to datasheet but I suspect it's making the gain too higher. The datasheet says the typical gain is 50db. 1. Could it be the reason for the motorboating ?
2. If so How can I reduce the gain of the circuit ?
3. If possible, please do a video on this chip Ta8210 for better understanding about this chip for everyone. Thanks in advance
Can I make an amplifier out of TDA4864AJ?
How did you set up fft on your scope. I got my first scope (siglent sds 1202X-E)
But I still didn't figure out how to set up fft. Is there some tutorial or something?
Kissanalog channel made a tutorial on setting up the FFT on a siglent scope. That's what helped me.
@@JohnAudioTech Oh, thanks man
disapoint .. i have this chip TEA2025B on a 2,1 speakers system and sound amazing for them power and heatsink what they have. One chip is on bridge mode to subwoofer 6 ohm, and 2st chip are in stereo mode 4 ohm speakers . i change transformer from 9v 1.1A to smps 12v 2.5A. i dont measure power on satelites speakers , but on subwoofer i have max 10v on output. at 7,5 - 8V is not even 0,5% distorsion and nothing.something wrong on your design or power supply or heatsink is needed
So what's the problem? After I got the circuit working properly, it is a good amplifier. I see no distortion above ~.3% in bridged mode which is great for this IC. With around 1.1 amp rms max output current, I would be leary of pushing it too hard with the reactive load of an 8 ohm speaker at 12 volts supply.
Hi John, I would like to send a 4 transistor amplifier pcb that you could build and review. I need the address to send it to.
Did you look in the description? There might be something in the description.
like for ampli n for cat
Two months too late... I already burnt mine...
Amp with 30 years old and obsolete crappy chip... What's the purpose of this?
To appreciate what you have now, you have to see how you got here.
30 years ago this was state of the art.
@@piconano state of the fart?
@@bernardmarx6705 The purposy of this is knowledge. We get to aquire knowledge. For example, I bet that many guitar players would love to own an overdrive pedal built with this chip because of its soft clipping, I'm sure they would pay a lot for that.
FirstName LastName , because, these are actually, pretty good little amplifiers. And, seeing them put together is interesting.
@@CalebePriester haha, go ahead..