Been binge watching your videos this week. I have an cheap pre made(don't hate me) single supply tda2030 and was wondering if it's possible to change the bandwidth to use it as a mini subwoofer amp? Between 40hz-140hz -ish? I don't know very much about it but you said the input capacitor affects the low frequencies. Maybe change it to 4.7uF or so? How about the high frequencies? Thanks btw I love how you explain things in your vids. Keep em coming!
mine is very very noisy (noise that has a hint of the music not the music with noise) and the produced sound is unusable, is it because I did it on a breadboard or my ic is faulty?
Hi John. Enjoy your audio amp videos and I think you're the right kind of person to ask a problem I found with the LM1875. I built this audio amp with the plus and minus power supply and as closest I could following the schematic provided in its datasheet. Now my problem is that it heats up too much with NO load applied to it, and just working with +- 8 volts the heat increases. Then as the voltage increases even more, so it does the heat to the point it gets too hot to touch it, and even with a good heat dissipation. Is that something normal with this type of IC's? I'm trying to use it with a +-20 volt supply but I can't even get close to it because of the heat. I'm worried it would fry up. Any recommendations? I will greatly appreciate it, thanks.
Hello John, Great video m8. I have a question about power supply's for this circuit. I have a linear with three outputs two being variable 0-30v at 5 amp each and a fixed 5v 3amp. Can I use it to build this circuit? I am new and confused about +25v and -25v. Cheers.
MonkeyMagic Elecifun The chip needs what's called a bipolar supply. Relative to the ground (or 0 volt line), it needs a positive voltage and a negative voltage. Most dual power supplies allow you to set them up this way (check your manual). You have enough voltage and current. Use + & - 25 volts for 8 ohm loads and + & - 18 volts max if your load is 4 ohms. You can also use a single supply but you need extra parts to make it work. (too much to explain here).
Hello John, I love your videos. You do s really good job making videos. You seem to answer the questions I have as I m watching . I do have a question though. In the data sheet it shows a 2200uf cap on the positive output to the speaker. I see you don't use any capacitor Why does the data sheet show such a large capacitor? Thanks in advance. And keep up the GOOD WORK.
Hey john, I'm a bit confused about the + and - rails and if you connect the - rail to the grounds on the board or the ground to the grounds on the board. Anyway, great video and keep up the content! Cheers.
+GkAudioTech With a dual rail supply that has +, ground and -, connecting the - to ground would short it out. Connect only the ground of the supply to the ground of the amp circuit. In the case of the LM1875, the negative rail goes to pin 3 and the positive to pin 5. Many thanks for watching my videos.
HI John AT, Good job, learning a lot about chip amps, thanks to your videos. Been looking for new uploads. Do you build your own dual supply, pos, neg to power your amps? Probably easier to buy one, but not as much fun. I've built my own positive supply for a Ruby Amp I am working on, dual not much different. Thankyou for videos, and, Have a Happy Thanksgiving. C.
I have two questions - 1. In some branded home theatre systems, there are two different input sockets. One is RCA type and marked "Cd/Dvd player" and another is Stereo type which is marked "Computer". Are these both sockets directly connected to the amplifier input or have some special function ? 2. Where can we get the heatsink with larger fins you used here ?
1. They are probably both line level and just labeled that way for convenience. 2. I got the heatsink from an old TV. Heat Sink USA sells them of various sizes.
hi John. If I wanted to build a top notch version of this 100 bucks or less just for the amp boards could you give me the parts list. I wanted sound quality first in this build. Thanks in advance for your time and effort.
Really enjoy your Channel, just subscribed. I'm looking to build my second amp with this chip and struggle with determining the wattage for the resistors. I understand Ohm's Law, but I generally see one resistor that is larger (in size) from the others, which I'm assuming is 1/4 or 1/2 watts. Can you shed any light on this or share what the wattage value is for that one larger one? Much appreciated.
Could you tell me how much voltage you were supplying to your + and - rails? I am building a similar project and Im not getting anywhere near 25-30 watts of output. Also I am using the schematic that came with the 1875.
Philip Geraci At +&- 18v rails I measured 25w of clean power into 4 ohm load or +&- 22v into 8 ohms for the same 25w. Supply voltage is measured with amp delivering the 25w with continuous sine wave. Of course, voltage will be a higher at idle. Those are the max voltages I'd use with this IC. If you need more power use a stronger IC like the LM3886 or LM3875.
I have it going pretty well now, but it is doing something strange. It sounds great at first but after about a minute or two the lows start getting distorted more and more. I am thinking maybe a heat issue? Of course I do have it heat synced decently, or so I thought.
Philip Geraci Likely a component layout issue. You have to keep the parts close to the IC and be sure high currents from the output and power supply are not flowing in the same leads as the small signal grounds (input and feedback).
Hey John, thanks for the videos! Do you have a idea for an amp that can be used to run a dynamic mic? I hacked a Aiwa cassette player by tapping into the cassette head but that won't drive the mic. It also produces a lot of hum when I plug in a guitar and touch the strings. Thanks for your help.
zardozica Hi, Op amps are good pre amps that are in front of the power amp for the extra amplification needed for a mic. You can also use a transistor preamp stage. I might do a preamp video at some point. Be sure the ground is not reversed with input on a guitar or you will get very loud hum when touching metal parts on it.
I tried building this amp as a project with the single supply schematic on the datasheet, but it doesn't work. There's nothing coming out of the speaker, it only makes a "pop" sound when i turn it on/off. What do you think this could be?
I took the amp out and inspected the board very carefully, and I noticed a small solder bridge between a resistor and ground. I rectified it and now the amp works perfectly! If you hadn't responded I probably would've never taken it back out again. Cheers man!
Yes 1A is fine per amplifier (2A for stereo). It has to be rectified using a full wave bridge to create a +12 and -12 volts split supply. Google a split (or dual) powersupply for correct setup.
Hey John, I have watched a lot of your video's and have enjoyed them all. In one of your LM1875 video's, you have one with flat, straight leads. Do you have the part number for that variation? It would work well for the setup I am working on. I could straighten the leads on ones I have but the leads are very brittle and easy to break. I do not want to solder the chips directly to my board, I have purchased sockets made for these 5 lead chips. Spent more on the sockets than for the IC's. Thanks for your video's. Here is a link to the socket if you are interested: www.digikey.com/product-detail/en/TCC05DCSN-S1403/S9635-ND/4213430?OCE19RT&US&so=58032316&mkt_tok=eyJpIjoiTVRka1lURmtaREppWmpsaCIsInQiOiJMT2F2TDFOZ3FvTnh1ZDY1NDFqVGRpdWFjWGk5c1BXR0dNS3JDQ3RSekk1Q1VkQnRcL0lwQ2hGRUpaMXlQQVdyZWx6b2MyTkdYTFhQb2RNTUp2eERGajArUERaTkdTU3o0a1R0b29KVFdvMEZWMDhTeE5ueHhzTVd3TzNvcTVIdVwvIn0%3D
Well done. And thank you for the upload.
Thanks for watching!
I noticed Mr. John that you did not recommend to use a fan when you think the heatsink is not enough.
thANK YOU, John.
Thank you John...
Why all the interested in the LM1875? They are a cheap single chip low component count solution for entry level HI-FI gear, been around for decades.
Great video John. What happened to you tidy bench....?
Been binge watching your videos this week. I have an cheap pre made(don't hate me) single supply tda2030 and was wondering if it's possible to change the bandwidth to use it as a mini subwoofer amp? Between 40hz-140hz -ish? I don't know very much about it but you said the input capacitor affects the low frequencies. Maybe change it to 4.7uF or so? How about the high frequencies? Thanks btw I love how you explain things in your vids. Keep em coming!
mine is very very noisy (noise that has a hint of the music not the music with noise) and the produced sound is unusable, is it because I did it on a breadboard or my ic is faulty?
Hi John. Enjoy your audio amp videos and I think you're the right kind of person to ask a problem I found with the LM1875.
I built this audio amp with the plus and minus power supply and as closest I could following the schematic provided in its datasheet.
Now my problem is that it heats up too much with NO load applied to it, and just working with +- 8 volts the heat increases. Then as the voltage increases even more, so it does the heat to the point it gets too hot to touch it, and even with a good heat dissipation.
Is that something normal with this type of IC's?
I'm trying to use it with a +-20 volt supply but I can't even get close to it because of the heat. I'm worried it would fry up.
Any recommendations? I will greatly appreciate it, thanks.
Hello John,
Great video m8. I have a question about power supply's for this circuit. I have a linear with three outputs two being variable 0-30v at 5 amp each and a fixed 5v 3amp.
Can I use it to build this circuit? I am new and confused about +25v and -25v.
Cheers.
MonkeyMagic Elecifun The chip needs what's called a bipolar supply. Relative to the ground (or 0 volt line), it needs a positive voltage and a negative voltage. Most dual power supplies allow you to set them up this way (check your manual). You have enough voltage and current. Use + & - 25 volts for 8 ohm loads and + & - 18 volts max if your load is 4 ohms. You can also use a single supply but you need extra parts to make it work. (too much to explain here).
Hello John,
I love your videos. You do s really good job making videos. You seem to answer the questions I have as I m watching . I do have a question though. In the data sheet it shows a 2200uf cap on the positive output to the speaker. I see you don't use any capacitor
Why does the data sheet show such a large capacitor?
Thanks in advance. And keep up the GOOD WORK.
Thanks Rodney! I think what you are seeing is the amp setup in single supply mode where a coupling capacitor is needed on the output.
Hey john,
I'm a bit confused about the + and - rails and if you connect the - rail to the grounds on the board or the ground to the grounds on the board. Anyway, great video and keep up the content! Cheers.
+GkAudioTech With a dual rail supply that has +, ground and -, connecting the - to ground would short it out. Connect only the ground of the supply to the ground of the amp circuit. In the case of the LM1875, the negative rail goes to pin 3 and the positive to pin 5. Many thanks for watching my videos.
+JohnAudioTech Thanks mate,
I just looked at the datasheet of the amp chip and realized how stupid that question was.
HI John AT, Good job, learning a lot about chip amps, thanks to your videos. Been looking for new uploads. Do you build your own dual supply, pos, neg to power your amps? Probably easier to buy one, but not as much fun. I've built my own positive supply for a Ruby Amp I am working on, dual not much different. Thankyou for videos, and, Have a Happy Thanksgiving. C.
Cass Virgillo Hi cass, Glad to hear the videos are helpful! Yes, I build my own dual supplies.
I have two questions -
1. In some branded home theatre systems, there are two different input sockets. One is RCA type and marked "Cd/Dvd player" and another is Stereo type which is marked "Computer". Are these both sockets directly connected to the amplifier input or have some special function ?
2. Where can we get the heatsink with larger fins you used here ?
1. They are probably both line level and just labeled that way for convenience.
2. I got the heatsink from an old TV. Heat Sink USA sells them of various sizes.
hi John. If I wanted to build a top notch version of this 100 bucks or less just for the amp boards could you give me the parts list. I wanted sound quality first in this build. Thanks in advance for your time and effort.
Please stay tuned as I have an LM1875 board to review whenever it gets here. The board layout appears ideal for a high quality amp.
Sounds good. Ill be watching.
Really enjoy your Channel, just subscribed. I'm looking to build my second amp with this chip and struggle with determining the wattage for the resistors. I understand Ohm's Law, but I generally see one resistor that is larger (in size) from the others, which I'm assuming is 1/4 or 1/2 watts. Can you shed any light on this or share what the wattage value is for that one larger one? Much appreciated.
Glad that you enjoy the channel! The larger resistor is part of the output zobel and should be at least 1 watt.
@@JohnAudioTech Thank you, John, for the helpful reply. Cheers! -Norm
JohnAudio Tech can you make a video on how to make subwoofer amplifier thx
I'm working on a subwoofer preamp/filter circuit now.
Could you tell me how much voltage you were supplying to your + and - rails? I am building a similar project and Im not getting anywhere near 25-30 watts of output. Also I am using the schematic that came with the 1875.
Philip Geraci At +&- 18v rails I measured 25w of clean power into 4 ohm load or +&- 22v into 8 ohms for the same 25w. Supply voltage is measured with amp delivering the 25w with continuous sine wave. Of course, voltage will be a higher at idle. Those are the max voltages I'd use with this IC. If you need more power use a stronger IC like the LM3886 or LM3875.
I have it going pretty well now, but it is doing something strange. It sounds great at first but after about a minute or two the lows start getting distorted more and more. I am thinking maybe a heat issue? Of course I do have it heat synced decently, or so I thought.
Philip Geraci Likely a component layout issue. You have to keep the parts close to the IC and be sure high currents from the output and power supply are not flowing in the same leads as the small signal grounds (input and feedback).
+Philip Geraci maybe you'r using chinese made ic
Hey John, thanks for the videos! Do you have a idea for an amp that can be used to run a dynamic mic? I hacked a Aiwa cassette player by tapping into the cassette head but that won't drive the mic. It also produces a lot of hum when I plug in a guitar and touch the strings. Thanks for your help.
zardozica Hi, Op amps are good pre amps that are in front of the power amp for the extra amplification needed for a mic. You can also use a transistor preamp stage. I might do a preamp video at some point. Be sure the ground is not reversed with input on a guitar or you will get very loud hum when touching metal parts on it.
Good video, thanks. What is the metal can transistor @ 00:26 and what are you building with it?
Many thanks! The can transistor is a 2N3866 5 watt power RF transistor. I hope to experiment with RF at some point
Nice, look forward to the resulting vids.
I tried building this amp as a project with the single supply schematic on the datasheet, but it doesn't work. There's nothing coming out of the speaker, it only makes a "pop" sound when i turn it on/off. What do you think this could be?
Could be many things, but measure the voltage on pin 1. It should be about 1/2 the supply voltage.
I took the amp out and inspected the board very carefully, and I noticed a small solder bridge between a resistor and ground. I rectified it and now the amp works perfectly! If you hadn't responded I probably would've never taken it back out again. Cheers man!
Can I hook it up at +12V 2A power supply? Pin3 to the ground.
It requires a dual supply.
Will a 12v-0-12v 1A suffice?
Thanks for the help!
Rectified? +-12V
Yes 1A is fine per amplifier (2A for stereo). It has to be rectified using a full wave bridge to create a +12 and -12 volts split supply. Google a split (or dual) powersupply for correct setup.
Thanks bro! Commend.
Hey John, I have watched a lot of your video's and have enjoyed them all. In one of your LM1875 video's, you have one with flat, straight leads. Do you have the part number for that variation? It would work well for the setup I am working on. I could straighten the leads on ones I have but the leads are very brittle and easy to break. I do not want to solder the chips directly to my board, I have purchased sockets made for these 5 lead chips. Spent more on the sockets than for the IC's. Thanks for your video's. Here is a link to the socket if you are interested:
www.digikey.com/product-detail/en/TCC05DCSN-S1403/S9635-ND/4213430?OCE19RT&US&so=58032316&mkt_tok=eyJpIjoiTVRka1lURmtaREppWmpsaCIsInQiOiJMT2F2TDFOZ3FvTnh1ZDY1NDFqVGRpdWFjWGk5c1BXR0dNS3JDQ3RSekk1Q1VkQnRcL0lwQ2hGRUpaMXlQQVdyZWx6b2MyTkdYTFhQb2RNTUp2eERGajArUERaTkdTU3o0a1R0b29KVFdvMEZWMDhTeE5ueHhzTVd3TzNvcTVIdVwvIn0%3D