Some somewhat unusual design features enable this amplifier to be perfectly silent. No hum problems, finally! Link to the video: • DrCassette's Workshop ...
One thing I learned overtime working with amplifiers, is that you need to connect the speaker's negative terminal to the main supply capacitors negative in single supply configuration or to common point between the two capacitors (0V) in dual supply configuration. The copper trace on the circuit creates a very small resistance. If the amp. feed back is on the same trace you'll get hum. that's why in datasheet they present a recommended PCB design or they recommend a star ground connection. Hope this helps.
Nice design and re-purposing of the components you had at hand. Just make sure that the metal can and the screw are electrically isolated on the transformer.
I've also made a homemade amplifier with VU meter, and also had the dimming LED problem. All you have to do is use an LM7812 voltage regulator, but you have to feed it with higher voltage than 12 volts.
I remember the first working amp I ever built,based of the tda2003, had no hum at all in normal conditions, only when the supply was loaded very much and the voltage dropped below 3 volts things started to turn bad. Even ran one just from usb power (5v 100ma),worked ok, needed no heatsink
Looks very nice. My homemade amplifier has a little hum but I think that's a ground loop somewhere in it more than anything else. Interestingly enough most of my tube amplifier experiments sounded nicer and had no hum whatsoever.
NoBudgetTech I know those LM chips are good (gainclone) but I don't have any of those. The TDA2030A circuits I already had in my parts bin, only had to mount them to the heat sink.
Transformer center tap must be soldered into the chassis to avoid hum...from this point you should catch all ground points you need for input/output and secondary supplies.
Proof a very nice amplifier can be built for not a whole lot of money. Granted any high end audio company would not want the masses to know this. Hi end audio is WAAAYYYY over priced but what are ya gonna do...
Very nice build, simple and to the point, and what I like best-No HUM! The Toroids metal 'Hat' keeps a lot of the fields contained, nice. Just wondering, for the Meter led section, have you thought of running it off of a seperate, low power transformer, or, still tapped off the cap, but regulated ex: LM317, etc.. with a nice fat cap at input to regulator. (1000uF) it should cure the 'dimming' effect. I like the case too!
Scott x The hat of the toroidal transformer doesn't really make any difference, I tried the amp with and without. I'm now just leaving it on because I don't need it anywhere else. The LEDs were hooked up as simple as possible, an LM317 wired as constant current source would certainly fix the problem, but the input voltage wouldn't be high enough.
The hum is usually in older amplifiers the transformer that outputs a magnetic field Calles the stray field. usually 50hrtz. All the shielding indeed blocks it until a point we van no longer hear it, bt only see it on a scope. Have you did soms testing with different materials for shielding the transformer? In the video you did use aluminium for the transformer and metal for the PCB?
Have you tried experimenting with other metals? I have some old active hi-fi speakers that have a little hum that is caused by the electromagnetic (EM) or stray flux produced by the transformer when it's turned on and when it's close to the woofer (it is, and there's no way of moving it away). It's a little design error, but shielding with aluminium it didn't really go away. I could throw a toroidal transformer in both of them, but that's another 80 euros. For little improvement.
You may feel it better than other amplifiers....the reason of that is that you are using direct sound..not tone controls destroying quality including harmonics.. Second reason we feel the sound as better is because WE MAKE IT....if you compare with others under the same test conditions you gonna see that exist some difference.
Two things also I have to comment: First, rectifier bridge for two TDA2030A doesw not need heatsink. I use in my homemade amplifier four TDA2030A (two for stereo and another two in bridge formation for sub) and the rectifier does not even warms. Second, I don't think you need 22000uF capacity for two TDA2030As, that is too much, I managed to build an amplifier circuit with two TDA2030A in bridge formation with 4700uF capacitors, and it works like charm.
This amplifier was assembled from leftover parts. The rectifier bridge indeed needs to heat sink in this application - however, in the project the circuit board was originally designed for it was necessary.
With your power delivery system does that make those amps actually produce solid bass output? Basically what I'm trying to understand is how solid bass is actually achieved.
Thanks quite an improvement for just using a quality filter capacitor. I so want to build an amplifier now. Ive never built one before but thought about it for quite a while now. I have 6 BCAP0350 E270 T11 d cell maxwell ultra capacitors but im assuming those are way more than I need haha.
Sean S I'm sorry, but those caps are absolutely useless. These supercapacitors are designed as a replacement for a rechargeable battery for backup power applications. The maximum voltage they can take is 2.7 V. An amplifier will often run on 10 times that much voltage!
One word of warning, which you probably know already... but others may not: Be VERY careful with metal cans round toroidal transformers. If they are connected at each end via the centre bolt, they form a short circuit turn and tend to either blow fuses or result in redhotness!
***** What are you talking about? If the transformer is properly insulated with the windings intact, there is no way this could cause a short circuit. All it does is messing with the magnetic field.
DrCassette The metal surround along with the bolt is effectively a loop round the core, so forms a short circuit turn. ref: www.raftabtronics.com/TECHNOLOGY/ElectromagneticBasics/TransformerBasics/tabid/110/Default.aspx#Toroidal_cores
EastAngliaUK About 18 W RMS I think. Take a look at this video: th-cam.com/video/eRFxe6m7k-E/w-d-xo.html The chips measured in that video are basically the same as the TDA2030A.
A CATAL I think you don't even understand what you are asking. You could do the math yourself, but since you probably can't, 18 Watts comes out as 12,55 dBW.
DrCassette thank you. Congratulations for taking all small details in the building!! It seems that the power is not something special, but as I told you, details count a lot.
Rather than TDA2030, why don't you use TDA7265? Contains 2 TDA2030 in one package plus standby/mute input and stability improvement. Cheers from Indonesia
Blissy28 Which ground do you mean? Of course the case is connected to ground. The system ground. So it becomes shielding for the amplifier circuits. It is not connected to safety ground. It's unnecessary because all mains related elements are very well insulated. And the primary fuse is going to blow in case of a short.
Sorry. What is the purpose of a heatsink if it has no airflow around it?! You could have mounted the amplifier against the side of the cabinet and the heatsink in the same place, from the outside! :D
+DrCassette But it has to. That is the purpose of a heatsink. If you keep it enclosed inside a box with no airflow, it will most probably render useless over a long period.
+Matheus Moreira Not necessarily. The heat sink will dissipate the heat into the air enclosed in the box. The heated air will then heat the outer case. The case will then dissipate the heat to the outside. So the heat does have a way to get out of there, just the overall thermal resistance is MUCH higher than in other, more efficient setups. However, that's not an issue in this case.
One thing I learned overtime working with amplifiers, is that you need to connect the speaker's negative terminal to the main supply capacitors negative in single supply configuration or to common point between the two capacitors (0V) in dual supply configuration. The copper trace on the circuit creates a very small resistance. If the amp. feed back is on the same trace you'll get hum. that's why in datasheet they present a recommended PCB design or they recommend a star ground connection. Hope this helps.
The two level meters are beautiful!
Fantastic video and just what I was looking for as I am about to build a very similar amp using 2 TDA7293 boards. Thanks for your effort.
'special because it actually works'
wow i like that phrase
Excellent job. Thanks for sharing your knowledge.
Nice design and re-purposing of the components you had at hand. Just make sure that the metal can and the screw are electrically isolated on the transformer.
Of course they are isolated from the transformer...
@@DrCassette Good :) I couldn't see very well in the video, so that's why I said it. That's a trap for young players, as Dave would say :D
I've also made a homemade amplifier with VU meter, and also had the dimming LED problem. All you have to do is use an LM7812 voltage regulator, but you have to feed it with higher voltage than 12 volts.
I remember the first working amp I ever built,based of the tda2003, had no hum at all in normal conditions, only when the supply was loaded very much and the voltage dropped below 3 volts things started to turn bad.
Even ran one just from usb power (5v 100ma),worked ok, needed no heatsink
Looks very nice. My homemade amplifier has a little hum but I think that's a ground loop somewhere in it more than anything else. Interestingly enough most of my tube amplifier experiments sounded nicer and had no hum whatsoever.
CoolDudeClem I have experimented with that preamp circuit, you may have seen that video. That also worked out quite well.
Very nice amp! I'd recommend using LM1875T in place of the 2030A, that would make it a proper high-end amp.
NoBudgetTech I know those LM chips are good (gainclone) but I don't have any of those. The TDA2030A circuits I already had in my parts bin, only had to mount them to the heat sink.
Then go buy some LM1875 :D Very good build, it would be a shame to waste it on some TDA chips, tho.
I said I'm working on something better, so for the time being these TDAs will be good enough.
Transformer center tap must be soldered into the chassis to avoid hum...from this point you should catch all ground points you need for input/output and secondary supplies.
+Carlos Mergulhão
That's what I did.
Interesting nice video
That's a nice project m8. I would be well proud to build it. Big Thumbs Up from me.
+MonkeyMagic Elecifun Thanks :)
Proof a very nice amplifier can be built for not a whole lot of money. Granted any high end audio company would not want the masses to know this. Hi end audio is WAAAYYYY over priced but what are ya gonna do...
Always secondary center tap should be soldered (not screwed) into the chassis
Very nice build, simple and to the point, and what I like best-No HUM! The Toroids metal 'Hat' keeps a lot of the fields contained, nice. Just wondering, for the Meter led section, have you thought of running it off of a seperate, low power transformer, or, still tapped off the cap, but regulated ex: LM317, etc.. with a nice fat cap at input to regulator. (1000uF) it should cure the 'dimming' effect. I like the case too!
Scott x The hat of the toroidal transformer doesn't really make any difference, I tried the amp with and without. I'm now just leaving it on because I don't need it anywhere else. The LEDs were hooked up as simple as possible, an LM317 wired as constant current source would certainly fix the problem, but the input voltage wouldn't be high enough.
Always use shielded cables to audio input and volume control
+Carlos Mergulhão
I did.
The hum is usually in older amplifiers the transformer that outputs a magnetic field Calles the stray field. usually 50hrtz. All the shielding indeed blocks it until a point we van no longer hear it, bt only see it on a scope. Have you did soms testing with different materials for shielding the transformer? In the video you did use aluminium for the transformer and metal for the PCB?
It's actually both metal.
Have you tried experimenting with other metals? I have some old active hi-fi speakers that have a little hum that is caused by the electromagnetic (EM) or stray flux produced by the transformer when it's turned on and when it's close to the woofer (it is, and there's no way of moving it away). It's a little design error, but shielding with aluminium it didn't really go away. I could throw a toroidal transformer in both of them, but that's another 80 euros. For little improvement.
Aluminium doesn't work for shielding a magnetic field. You need a material that's magnetic to shield the transformer's magnetic field.
Thanks for the comments, cool project +1
Will you sell me a TDA2030a? I blew mine.
If not, can you tell me what used audio equipment one could likely be found in?
Nice work! It's better to utilise things like this, than have a pile of 50 broken units cluttering up your workshop
Try LM3886
Carlos Mergulhão a304Tebby
You may feel it better than other amplifiers....the reason of that is that you are using direct sound..not tone controls destroying quality including harmonics..
Second reason we feel the sound as better is because WE MAKE IT....if you compare with others under the same test conditions you gonna see that exist some difference.
Two things also I have to comment:
First, rectifier bridge for two TDA2030A doesw not need heatsink. I use in my homemade amplifier four TDA2030A (two for stereo and another two in bridge formation for sub) and the rectifier does not even warms.
Second, I don't think you need 22000uF capacity for two TDA2030As, that is too much, I managed to build an amplifier circuit with two TDA2030A in bridge formation with 4700uF capacitors, and it works like charm.
This amplifier was assembled from leftover parts. The rectifier bridge indeed needs to heat sink in this application - however, in the project the circuit board was originally designed for it was necessary.
Ok, thank you for the answer.
nice build. are those tantalum on the bigger capacitor?*
If I recall correctly, the small capacitors are indeed tantalum.
With your power delivery system does that make those amps actually produce solid bass output? Basically what I'm trying to understand is how solid bass is actually achieved.
Watch this video for further information: th-cam.com/video/Ryoieu6kc-0/w-d-xo.html
Thanks quite an improvement for just using a quality filter capacitor. I so want to build an amplifier now. Ive never built one before but thought about it for quite a while now. I have 6 BCAP0350 E270 T11 d cell maxwell ultra capacitors but im assuming those are way more than I need haha.
Sean S
I'm sorry, but those caps are absolutely useless. These supercapacitors are designed as a replacement for a rechargeable battery for backup power applications. The maximum voltage they can take is 2.7 V. An amplifier will often run on 10 times that much voltage!
Are the VU meters from the sankyo cassettedeck
Nice homemade amplifer
+Cassette trainmania1992 Correct.
@DrCassette What scheme you use, thanks!
The standard split rail schematic in the TDA2030A datasheet.
One word of warning, which you probably know already... but others may not: Be VERY careful with metal cans round toroidal transformers. If they are connected at each end via the centre bolt, they form a short circuit turn and tend to either blow fuses or result in redhotness!
***** What are you talking about? If the transformer is properly insulated with the windings intact, there is no way this could cause a short circuit. All it does is messing with the magnetic field.
DrCassette The metal surround along with the bolt is effectively a loop round the core, so forms a short circuit turn.
ref: www.raftabtronics.com/TECHNOLOGY/ElectromagneticBasics/TransformerBasics/tabid/110/Default.aspx#Toroidal_cores
how many watts RMS each channel would it do?
EastAngliaUK About 18 W RMS I think. Take a look at this video: th-cam.com/video/eRFxe6m7k-E/w-d-xo.html
The chips measured in that video are basically the same as the TDA2030A.
A CATAL I think you don't even understand what you are asking. You could do the math yourself, but since you probably can't, 18 Watts comes out as 12,55 dBW.
Can I have a parts list and parts source?
This uses the circuit for a split power supply shown in the date sheet of the TDA2030A.
What power does this amp is able to deliver into 8 ohm?
About 12 W RMS per channel according to the datasheet.
DrCassette thank you. Congratulations for taking all small details in the building!! It seems that the power is not something special, but as I told you, details count a lot.
Rather than TDA2030, why don't you use TDA7265? Contains 2 TDA2030 in one package plus standby/mute input and stability improvement.
Cheers from Indonesia
I had the TDA2030As readily available unlike the TDA7265 which I would have had to order. And I don't need the standby / mute feature.
100n shorting the meter input posts
Please ground the metal housing. Youre using just 2 wire mains input.
All components carrying mains voltage are properly insulated, so there is nothing wrong with that.
Neat, what was it originally?
Joshua's Recordings It doesn't matter anymore...
DrCassette I know it doesn't matter. I just wanted to know.
+Joshua's Recordings The Sankyo STD-2000 cassette deck...
Looks nice but you culd have used a much smaller case for it sens youre useing such tiny amp maduals
Is that case even grounded ??
Blissy28 Which ground do you mean? Of course the case is connected to ground. The system ground. So it becomes shielding for the amplifier circuits. It is not connected to safety ground. It's unnecessary because all mains related elements are very well insulated. And the primary fuse is going to blow in case of a short.
Sorry. What is the purpose of a heatsink if it has no airflow around it?! You could have mounted the amplifier against the side of the cabinet and the heatsink in the same place, from the outside! :D
Matheus Moreira The size of the heat sink compensates the lack of airflow. I didn't want the heat sink to stick out anywhere.
+DrCassette But it has to. That is the purpose of a heatsink. If you keep it enclosed inside a box with no airflow, it will most probably render useless over a long period.
+Matheus Moreira Not necessarily. The heat sink will dissipate the heat into the air enclosed in the box. The heated air will then heat the outer case. The case will then dissipate the heat to the outside. So the heat does have a way to get out of there, just the overall thermal resistance is MUCH higher than in other, more efficient setups. However, that's not an issue in this case.