Hello John, Great video and tips on a good build. The chip sounds good to me. Thanks fur all you do making your excellent video tutorials on chip amps, Snickers helps when he's not napping. Glad you weren't adversely affected by the crazy wind storm that hit the mid west. Hope your Brother is doing well, glad you are. We had 100 degrees over the weekend, back to the mid, upper 70's. All the best from Oregon, C.
i agree, an rf filter is necessary. i get horrible GSM buzz on mine, which a 100pf/680r folter helped with, but didn't totally eliminate. I also get an intermittent 'click' about 1hz, but only when the input is disconnected. When its connected to a source, even if nothing is playing, the clicking stops. very odd. almost seems like the chip is trying to enter a low power mode, or an automatic gain control is looking for a signal
Thanks again John for sharing. My hobby has taken a bit of a hit due to "current events" but I continue to enjoy learning from you. Is it pre-requisite that electronics guys have QC cats? Seems to be every channel I watch. My two boys, Buddy and Buster think so too.
Good little amplifiers! For their age, today we have the PAM8403 which is more powerful at 3W per channel and can run off a USB 2A charger! But it's class D and though it sounds great for portable applications, the TDA's might sound better! A comparison between the two would be great! Run both at the same time and use both channels on your oscilloscope, is it possible to have both amplifier outputs showing up on the FFT at the same time? That would be great, Being able to see both colours of the trace together and during the FFT you can see which one has a lower noise floor! If that's possible though.... Those tiny PAM amplifiers are pretty amazing for their size! I have seen another video somewhere else where someone used one to power full size 3 way Hifi speakers that had a 12 inch bass driver! 3 watts doesn't sound like much and people laugh when you tell them it's power output but the laughing stops as soon as the music starts! It might seem like I'm promoting this little amplifier, hell I don't even like class D amplifiers! But even I will admit that it's pretty impressive for it's size. If that's not enough power, it has a bigger brother that needs 12V and has a staggering 10W output and it's also pretty small for it's size... You might have already covered these Amplifiers earlier and I'm sure that if you have, I have definitely seen them but I can't remember, I'm going to go and have a look if you have a video on it...
Hi John, great video! I'm a somewhat recent subscriber so I probably missed it... you mentioned a couple times solid state amplifiers (only those chippies or generally?) have a hard time delivering low distortion at higher frequencies. Why is that?
I'm pretty sure he was talking about chip amps, if I'm remembering a previous video correctly. In answer to that question, it's mostly to do with circuit tolerances, layout, design, etc. and I'm talking internal to the chip. Discrete amplifiers (all transistor) can be "tuned", so to speak, at stages like the input, VAS and drivers, or you can take different design routes such as a cascode VAS to lower distortion figures.
Higher distortion at higher frequencies is normal with any feedback amplifier because there is less loop gain (working margin) for the cancellation of non linearities in the circuit at higher frequencies.
Can I use an amp like this with +/- 12V supply, feed it 10Hz~10KHz @ 1VPP AC from a signal generator chip, and get +/-12V AC output into a 50 Ohm load? If not, what do you recommend? My signal gen is a cheap < $10 kit and has no drive capability beyond
I don't think the chip could handle driving a 50ohm load. As for using a split supply, pin 6 needs to connect to the other side "grounds" of the chip to work, as pin 6 is negative, I don't think it would work. You can get what you want by using an opamp. You'll need one that can handle low impedance on its output.
Ultimately, you could do something similar to this sound-au.com/project113.htm using output transistors in the feedback path of the opamp which will allow you to drive lower impedance loads.
You cannot use this chip with +-12V supply. Its single supply max voltage swing is 18V. But using an audio amplifier IC is indeed a reasonable enough way to go. Note that +-12V driving a sinewave are not 12V AC but about 8.5V AC but you probably knew that. I'm thinking you're looking for something like TDA2030 or similar (TDA2050, LM1875) as the simplest thing. You can even get PCB kits with all the parts for barely no money at all, very low effort.
Was going to ask your thoughts on the TDA7052 since the 7267 was obsolete but I see that the 7052 is listed as obsolete also. Odd since I just bought some around the beginning of the year. Built up a 7052 to replace an lm386 circuit. No output cap needed.
I was going to do a new video on the 7052 and found it obsolete. I did make a video on it a while back. Being bridged, you get decent power from 5 or 6 volts.
@@JohnAudioTech Surface mount version of TDA7052 is continuously manufactured by UTC Unisonic Tech Taiwan, so you can always get a little adapter board and plop it on.
I have a question I did not seem to find a answer for. I have some more powerfull amp chips in use (from 150 to 500WRMS at 4 ohm) why do these kind of chip amps start "playing" music on their own (from the chip itself) when they are pushed to their rated power. This always concerns me that they will blow up, because this is kinda related to the amps blowing up? Any information to that?
Great video, but the question begs, why not use the next generation version of these chips, or their replacement?! There is a reason they are obsolete now. Thank you for the great info!
Look into "capacitance multiplier", there's a good EEVBlog video about it. Not sure if it's easy to handle high currents, however. Increasing the capacitors value (and quality) might be the easiest way I know of, otherwise
HI! wanna know if i hook a 4ohm 25 watt speaker to a higher output amplifier, lets say 50+watts; will it kill the speakers? if you think this is a big issue please make a video on this topic. Thank you!
@@JohnAudioTech is there any way to cap that? so mistakenly someone won't burn out the voice coils? will replacing the volume control with half the resistance work? whats the calculation here? Thanks
What is the maximum voltage can we use for Lm3886? I have a 24-0-24 5 amp transformer can I use it to power LM3886? Because after rectification it will be come 33.84V +/-. Will the chip withstand that?
NE5534 or NE5532 (dual), but I would use a push/pull emitter follower transistor "booster" on the output within the feedback network to handle the lower impedance(s).
There is/was a chipamp made for "hifi" headphone use. I don't recall the part number off hand. It has very low noise and distortion. Something I need to look into although I'm not a headphone user.
@@JohnAudioTech Me either, or I'd try to revive my electrostatics. Looking to suggest a chipamp board for my friend Kurt's pre-amp, which now has a fairly stout +/- 15V PS.
Not sure whether best and not specifically a chip amp, so no preconfigured gain, no turn on pop control, muting, etc, but i'm thinking of NJM4556, it's a high spec (very low noise and distortion) general purpose/audio opamp that is incidentally pretty good at driving headphones. The spec is 80mA current sunk and sourced but it actually won't even start struggling below like 110mA or more, and it appears to be short circuit safe. Its use to drive headphone outputs in HiFi component systems is pretty traditional, used to be found all over the place, and it's good for such higher split supply voltages. The 4556AL version is in-line and lays out beautifully on a veroboard. Another option to consider is a traditional headphone amplifier with a NE5532 opamp driving discrete output transistors, JAT made a video on one, and also ESP Project 113, which are nearly identical. These also have exemplary performance. I suppose neither is quite what you ask for, sorry :(
TDA? you mean TPA by any chance? TPA3110, TPA3116 etc. Else i don't know what you mean. Well technically you could put these up front, one per channel, and you'd get gain, and nothing horrible will happen, but this seems to not be the best idea, unless you need them to pull double duty of some kind. For one this has fixed 30db gain, and TPA chips also have onboard gain, so if you need extra gain, this seems like a lot of gain to be adding and you're not terribly likely to need nearly as much; for other TPA are vaguely close to high fidelity chips, these are a step down. You want a preamp to at least not make the amplifier worse, and there seem to be plenty parts of the parameter space where either is worse. Any typical audio opamp (even generic non-TI 4580 as perhaps the cheapest i can think of, though something more solid like NE5532 is more ideal) should just be so much cleaner.
@@SianaGearz yes i meant TPA. thanks for all that info. i was thinking about the current draw on the tda7267, as the equivalent impedance of tpa3118 is unknown. And have an old tda7267 board lying around with tone control so before i do something terrible ..
@@SianaGearz this TDA7267 takes line in from my PC n is also powered by the smps(PC) 12v rail. and it makes a ton of background noise (ssd being read, mouse movement etc)at high gain but when i change the power source from smps(PC) to ext. it goes away. so im pretty sure the TPA3118 is going to just exaggerate this noise like hell. Do tell me if there is a way to cancel this noise. i even tried the PAM8610 with line in as pc and power as 12v smps(pc) n it went into a frenzy of oscillations at the output.
@@DeeP_BosE You have a ground loop. One ground is going through the audio connection from PC to amplifier. One ground is going through the 12V connection from PC to amplifier. You might as well leave the audio ground out and it might get a whole lot better - but this isn't quite a proper and complete solution. But please just try it quick for now :D The problem with this is that you wouldn't be able to connect a floating source (i.e. powered by battery or a separate unearthed PSU) to the audio input then. Even if you use a different ATX PSU than the one powering your PC, you still deal with the ground loop, because each ATX PSU connects its output ground to the house earth, so both are still connected. In this case the ground loop is even longer and nastier. The issue is fundamentally a little bit of induced ground current, which comes from RF, it comes from your PC, it also comes from an amp, it comes from everywhere, and it forms on the loop antenna. When working against the input of the amplifier, whatever the first stage is - whether preamp or directly into the input of power amp - you will find invariably that the input impedance of the amplifier is out of the box very high, hundreds of kOhms, Megaohms, that order of magnitude, so it almost doesn't consume any current from the signal inputs. Conversely any little bit of current forced onto the audio line appears as a significant voltage on the input. PAM are particularly nasty susceptible to induced noise, and i think this has to do with input impedance more than anything, but for sure Class D are also noise sources in general. You can make use of the fact that the PC soundchip is actually designed to drive higher current loads and make it work a bit, just a little bit, by far not as hard as when driving headphones, by connecting maybe 1K resistance against the inputs, between the input ground and the corresponding signal, very close to the amplifier, as close as possible. Then the current will basically largely go into this resistance and induce orders of magnitude less voltage to be sensed on the amp inputs. Care must be taken examining the input circuit of the amplifier board, as the input coupling caps can form a highpass against the resistor, and the capacitance may need to be beefed up, or the resistance may need to be increased. Also suggested reading: Texas Instruments Application Report SLOA143 - Ground Loop Break Circuits and Their Operation. As a quick and shitty way to implement ground loop break, you can simply insert a resistor into the audio ground, value 10-150 Ohm thereabouts. You're looking for a value that is several orders of magnitude higher than PSU ground path resistance, which is going to be ideally so low, you can't even measure it. Unfortunately when used with 1k resistors or the like, like i mentioned above, against the inputs, there may be some loss of stereo separation, but i mean, it's really not necessarily a big deal, mere paper figure anyway. So what this will do is similar to removing the audio ground altogether, forcing ground currents mostly one path only and mostly removing the loop, but still maintain compatibility with floating devices. Another family of measures is filtering. You have seen those ferrite beads on the cables, they act as common mode chokes, i.e. they suppress common mode currents, especially in RF. So ideally you have signal current going up L and R channels to the amplifier, and the same amount as the sum of those currents over audio ground back in reverse direction, so that's purely a differential mode current, and a ferrite like that or a common mode choke doesn't pose a significant resistance to currents going in this configuration, but if current is trying to go the same way in L and R and in GND, so common mode, it poses a higher impedance to that. I don't find that this is usually a massive help, but it's a bit of signal hygiene that won't hurt. Like even if the output opamp can fight the induced noise successfully, ideally you want to limit it at least somewhat. You can also build a nice serious common mode choke for the power inputs to the amplifier, that can be quite effective. After the choke, you put a capacitor bank, so it also has LCL and Pi filter like action. Which measures you should choose? I don't know. Try things, different people have different preferences. JAT seems to like impedance reduction on the amplifier inputs, uses like 10k. But i mean if you have a volume control potentiometer there, it will do that too. So i would do that, but i also like winding chokes.
I was thinking while watching it's not far off the performance of my amplifier which weighs 300 times more, consumes seven times the power, runs a 100 degrees hotter and lasts less time. Triode connected single ended EL84s. Wonder how they compare otherwise?
Well, in the terms of sound, valves/tubes give a "warmer" sound and softer (often more nice sounding) clipping compared to their solid state counterparts.
@@JohnAudioTech It sounds amazing. Big as life. I've never quite understood how transistor amps diminish the apparent size of everything..Elvis ends up being six inches tall and a drum kit can fit in your suitcase. Scale, dynamics and resolution all come pouring from it tricking you into seeing a real performance.. If it is 'just distortion' I'll take it.
Ah yes, the first watt has always been the most important 1000mw of music. They should make a newer, modern version of these; and just focus on 1-watt@8ohm.
I bought some of these last year, just because these are your favorite surface mount chip amps.
They worked fine.
I've made a few of the LM386 done rights ... it plays music in background as I write this. Now I'm making this done right circuit for a friend gift.
As always, excelent job! Thank you.
Thank you Jhon for sharing.
Hello John, Great video and tips on a good build. The chip sounds good to me. Thanks fur all you do making your excellent video tutorials on chip amps, Snickers helps when he's not napping. Glad you weren't adversely affected by the crazy wind storm that hit the mid west. Hope your Brother is doing well, glad you are. We had 100 degrees over the weekend, back to the mid, upper 70's. All the best from Oregon, C.
No wind here. 100 Deg in Oregon? Wow! Treatments have shrunk my bro's lung tumor quite a bit.
i agree, an rf filter is necessary. i get horrible GSM buzz on mine, which a 100pf/680r folter helped with, but didn't totally eliminate.
I also get an intermittent 'click' about 1hz, but only when the input is disconnected. When its connected to a source, even if nothing is playing, the clicking stops. very odd. almost seems like the chip is trying to enter a low power mode, or an automatic gain control is looking for a signal
As always, more than interesting... useful!
Thanks again John for sharing.
My hobby has taken a bit of a hit due to "current events" but I continue to enjoy learning from you.
Is it pre-requisite that electronics guys have QC cats? Seems to be every channel I watch. My two boys, Buddy and Buster think so too.
No. Although cute, cats are not necessary. Lol.
Cats and a fascination with lighting devices (at least for me).
I’m the “outlier” here, I have Sadie the Doggie as a helper and inspector🐶😊
Good little amplifiers! For their age, today we have the PAM8403 which is more powerful at 3W per channel and can run off a USB 2A charger! But it's class D and though it sounds great for portable applications, the TDA's might sound better! A comparison between the two would be great! Run both at the same time and use both channels on your oscilloscope, is it possible to have both amplifier outputs showing up on the FFT at the same time?
That would be great, Being able to see both colours of the trace together and during the FFT you can see which one has a lower noise floor! If that's possible though....
Those tiny PAM amplifiers are pretty amazing for their size! I have seen another video somewhere else where someone used one to power full size 3 way Hifi speakers that had a 12 inch bass driver! 3 watts doesn't sound like much and people laugh when you tell them it's power output but the laughing stops as soon as the music starts!
It might seem like I'm promoting this little amplifier, hell I don't even like class D amplifiers! But even I will admit that it's pretty impressive for it's size.
If that's not enough power, it has a bigger brother that needs 12V and has a staggering 10W output and it's also pretty small for it's size...
You might have already covered these Amplifiers earlier and I'm sure that if you have, I have definitely seen them but I can't remember, I'm going to go and have a look if you have a video on it...
Hi John, great video!
I'm a somewhat recent subscriber so I probably missed it... you mentioned a couple times solid state amplifiers (only those chippies or generally?) have a hard time delivering low distortion at higher frequencies. Why is that?
I'm pretty sure he was talking about chip amps, if I'm remembering a previous video correctly. In answer to that question, it's mostly to do with circuit tolerances, layout, design, etc. and I'm talking internal to the chip. Discrete amplifiers (all transistor) can be "tuned", so to speak, at stages like the input, VAS and drivers, or you can take different design routes such as a cascode VAS to lower distortion figures.
Higher distortion at higher frequencies is normal with any feedback amplifier because there is less loop gain (working margin) for the cancellation of non linearities in the circuit at higher frequencies.
Thank for the replies guys, much appreciated!
Yay! :) Sounds good.
Can I use an amp like this with +/- 12V supply, feed it 10Hz~10KHz @ 1VPP AC from a signal generator chip, and get +/-12V AC output into a 50 Ohm load?
If not, what do you recommend? My signal gen is a cheap < $10 kit and has no drive capability beyond
I don't think the chip could handle driving a 50ohm load. As for using a split supply, pin 6 needs to connect to the other side "grounds" of the chip to work, as pin 6 is negative, I don't think it would work. You can get what you want by using an opamp. You'll need one that can handle low impedance on its output.
Ultimately, you could do something similar to this sound-au.com/project113.htm using output transistors in the feedback path of the opamp which will allow you to drive lower impedance loads.
Google "line driver circuit". It is an op amp with output transistors added that can drive a 50 ohm load.
You cannot use this chip with +-12V supply. Its single supply max voltage swing is 18V.
But using an audio amplifier IC is indeed a reasonable enough way to go. Note that +-12V driving a sinewave are not 12V AC but about 8.5V AC but you probably knew that. I'm thinking you're looking for something like TDA2030 or similar (TDA2050, LM1875) as the simplest thing. You can even get PCB kits with all the parts for barely no money at all, very low effort.
@@JohnAudioTech Perfect. That's exactly the info I needed. I knew they exist, but didn't know what they're called.
Was going to ask your thoughts on the TDA7052 since the 7267 was obsolete but I see that the 7052 is listed as obsolete also. Odd since I just bought some around the beginning of the year. Built up a 7052 to replace an lm386 circuit. No output cap needed.
I was going to do a new video on the 7052 and found it obsolete. I did make a video on it a while back. Being bridged, you get decent power from 5 or 6 volts.
@@JohnAudioTech Surface mount version of TDA7052 is continuously manufactured by UTC Unisonic Tech Taiwan, so you can always get a little adapter board and plop it on.
I have a question I did not seem to find a answer for. I have some more powerfull amp chips in use (from 150 to 500WRMS at 4 ohm) why do these kind of chip amps start "playing" music on their own (from the chip itself) when they are pushed to their rated power. This always concerns me that they will blow up, because this is kinda related to the amps blowing up? Any information to that?
Great video, but the question begs, why not use the next generation version of these chips, or their replacement?! There is a reason they are obsolete now. Thank you for the great info!
IMHO, these were the best of their breed. It has all moved to class D or surface mount.
Thank you for the clarification. The price seems to be very reasonable on eBay coming from China. Very cool!
the "sillyscope " hahhaahaha good one !!
How to Bridge two tda7267a chip?
Hi John
Can you give us some ideas for clean amplifier rectifier circuits with right components that reduce noise low ripple ?
Look into "capacitance multiplier", there's a good EEVBlog video about it. Not sure if it's easy to handle high currents, however. Increasing the capacitors value (and quality) might be the easiest way I know of, otherwise
HI! wanna know if i hook a 4ohm 25 watt speaker to a higher output amplifier, lets say 50+watts; will it kill the speakers? if you think this is a big issue please make a video on this topic. Thank you!
You can do this as long as you don't crank the amp to high volume.
@@JohnAudioTech is there any way to cap that? so mistakenly someone won't burn out the voice coils? will replacing the volume control with half the resistance work? whats the calculation here?
Thanks
What is the maximum voltage can we use for Lm3886? I have a 24-0-24 5 amp transformer can I use it to power LM3886? Because after rectification it will be come 33.84V +/-. Will the chip withstand that?
Yes. And according to datasheet, it's safe to run over +-40V. I won't go over +-36V though.
+/-35V as a maximum if not running into a 4 ohm load, and +/-30V if running a 4 ohm load as according to the data sheet.
Hei jonh, can you try tea2025 ic amplifier
FeeeeelTech
What is the best chip-amp for a split 15V supply? To act as a headphone amp, quality more than max output.
NE5534 or NE5532 (dual), but I would use a push/pull emitter follower transistor "booster" on the output within the feedback network to handle the lower impedance(s).
There is/was a chipamp made for "hifi" headphone use. I don't recall the part number off hand. It has very low noise and distortion. Something I need to look into although I'm not a headphone user.
@@JohnAudioTech Me either, or I'd try to revive my electrostatics. Looking to suggest a chipamp board for my friend Kurt's pre-amp, which now has a fairly stout +/- 15V PS.
Not sure whether best and not specifically a chip amp, so no preconfigured gain, no turn on pop control, muting, etc, but i'm thinking of NJM4556, it's a high spec (very low noise and distortion) general purpose/audio opamp that is incidentally pretty good at driving headphones. The spec is 80mA current sunk and sourced but it actually won't even start struggling below like 110mA or more, and it appears to be short circuit safe. Its use to drive headphone outputs in HiFi component systems is pretty traditional, used to be found all over the place, and it's good for such higher split supply voltages. The 4556AL version is in-line and lays out beautifully on a veroboard.
Another option to consider is a traditional headphone amplifier with a NE5532 opamp driving discrete output transistors, JAT made a video on one, and also ESP Project 113, which are nearly identical. These also have exemplary performance.
I suppose neither is quite what you ask for, sorry :(
@@JohnAudioTech Perhaps the OPA134?
is it possible to use this as a pre amp for tpa311* amp?
TDA? you mean TPA by any chance? TPA3110, TPA3116 etc. Else i don't know what you mean. Well technically you could put these up front, one per channel, and you'd get gain, and nothing horrible will happen, but this seems to not be the best idea, unless you need them to pull double duty of some kind. For one this has fixed 30db gain, and TPA chips also have onboard gain, so if you need extra gain, this seems like a lot of gain to be adding and you're not terribly likely to need nearly as much; for other TPA are vaguely close to high fidelity chips, these are a step down. You want a preamp to at least not make the amplifier worse, and there seem to be plenty parts of the parameter space where either is worse. Any typical audio opamp (even generic non-TI 4580 as perhaps the cheapest i can think of, though something more solid like NE5532 is more ideal) should just be so much cleaner.
@@SianaGearz yes i meant TPA. thanks for all that info. i was thinking about the current draw on the tda7267, as the equivalent impedance of tpa3118 is unknown. And have an old tda7267 board lying around with tone control so before i do something terrible ..
@@SianaGearz this TDA7267 takes line in from my PC n is also powered by the smps(PC) 12v rail. and it makes a ton of background noise (ssd being read, mouse movement etc)at high gain but when i change the power source from smps(PC) to ext. it goes away. so im pretty sure the TPA3118 is going to just exaggerate this noise like hell. Do tell me if there is a way to cancel this noise. i even tried the PAM8610 with line in as pc and power as 12v smps(pc) n it went into a frenzy of oscillations at the output.
@@DeeP_BosE You have a ground loop. One ground is going through the audio connection from PC to amplifier. One ground is going through the 12V connection from PC to amplifier. You might as well leave the audio ground out and it might get a whole lot better - but this isn't quite a proper and complete solution. But please just try it quick for now :D The problem with this is that you wouldn't be able to connect a floating source (i.e. powered by battery or a separate unearthed PSU) to the audio input then.
Even if you use a different ATX PSU than the one powering your PC, you still deal with the ground loop, because each ATX PSU connects its output ground to the house earth, so both are still connected. In this case the ground loop is even longer and nastier.
The issue is fundamentally a little bit of induced ground current, which comes from RF, it comes from your PC, it also comes from an amp, it comes from everywhere, and it forms on the loop antenna. When working against the input of the amplifier, whatever the first stage is - whether preamp or directly into the input of power amp - you will find invariably that the input impedance of the amplifier is out of the box very high, hundreds of kOhms, Megaohms, that order of magnitude, so it almost doesn't consume any current from the signal inputs. Conversely any little bit of current forced onto the audio line appears as a significant voltage on the input. PAM are particularly nasty susceptible to induced noise, and i think this has to do with input impedance more than anything, but for sure Class D are also noise sources in general.
You can make use of the fact that the PC soundchip is actually designed to drive higher current loads and make it work a bit, just a little bit, by far not as hard as when driving headphones, by connecting maybe 1K resistance against the inputs, between the input ground and the corresponding signal, very close to the amplifier, as close as possible. Then the current will basically largely go into this resistance and induce orders of magnitude less voltage to be sensed on the amp inputs. Care must be taken examining the input circuit of the amplifier board, as the input coupling caps can form a highpass against the resistor, and the capacitance may need to be beefed up, or the resistance may need to be increased.
Also suggested reading: Texas Instruments Application Report SLOA143 - Ground Loop Break Circuits and Their Operation.
As a quick and shitty way to implement ground loop break, you can simply insert a resistor into the audio ground, value 10-150 Ohm thereabouts. You're looking for a value that is several orders of magnitude higher than PSU ground path resistance, which is going to be ideally so low, you can't even measure it. Unfortunately when used with 1k resistors or the like, like i mentioned above, against the inputs, there may be some loss of stereo separation, but i mean, it's really not necessarily a big deal, mere paper figure anyway. So what this will do is similar to removing the audio ground altogether, forcing ground currents mostly one path only and mostly removing the loop, but still maintain compatibility with floating devices.
Another family of measures is filtering. You have seen those ferrite beads on the cables, they act as common mode chokes, i.e. they suppress common mode currents, especially in RF. So ideally you have signal current going up L and R channels to the amplifier, and the same amount as the sum of those currents over audio ground back in reverse direction, so that's purely a differential mode current, and a ferrite like that or a common mode choke doesn't pose a significant resistance to currents going in this configuration, but if current is trying to go the same way in L and R and in GND, so common mode, it poses a higher impedance to that. I don't find that this is usually a massive help, but it's a bit of signal hygiene that won't hurt. Like even if the output opamp can fight the induced noise successfully, ideally you want to limit it at least somewhat. You can also build a nice serious common mode choke for the power inputs to the amplifier, that can be quite effective. After the choke, you put a capacitor bank, so it also has LCL and Pi filter like action.
Which measures you should choose? I don't know. Try things, different people have different preferences. JAT seems to like impedance reduction on the amplifier inputs, uses like 10k. But i mean if you have a volume control potentiometer there, it will do that too. So i would do that, but i also like winding chokes.
I was thinking while watching it's not far off the performance of my amplifier which weighs 300 times more, consumes seven times the power, runs a 100 degrees hotter and lasts less time. Triode connected single ended EL84s. Wonder how they compare otherwise?
Well, in the terms of sound, valves/tubes give a "warmer" sound and softer (often more nice sounding) clipping compared to their solid state counterparts.
Single ended tube amplifiers perform terrible on the test gear but many people like their sound. It's your tastes that matter in the end.
@@JohnAudioTech It sounds amazing. Big as life. I've never quite understood how transistor amps diminish the apparent size of everything..Elvis ends up being six inches tall and a drum kit can fit in your suitcase. Scale, dynamics and resolution all come pouring from it tricking you into seeing a real performance..
If it is 'just distortion' I'll take it.
the tda7267A is similar to lm380
Ah yes, the first watt has always been the most important 1000mw of music.
They should make a newer, modern version of these; and just focus on 1-watt@8ohm.
That was surprisingly good small amplifier! PAM 8403 is worse than this one.
nice music John, sounds pretty " ranchera "
A shame everything is going class d, not hating class d, but still, all these great class ab chips are being discontinued.
Great video and explanation, keep up this good work! I also make videos about electronics, if you are interested, check it out.