Thank God you made this video I actually ordered the amplifier based off your recommendation. When it came in I was very confused on how to hook it up. I feel like I'm going down a very deep rabbit hole that has no bottom.
No shit. Wtf is a dual supply amplifier? This is not the "they don't really sell power cables thick enough" kind of dual supply i have ever seen or thought about
I had a speaker DAC without power board and repaired like so; 4 zener diodes 12v*2 on negative and 12v*2 on positive, center between 4 diodes is the virtual ground. Used 2 parallels of 1 amp 12v diodes to get 2 amps on each ray and a 24v psu. If you don't mind the offset, your solution is much more practical! Great video!
I've been stymied, not being able to test some new amp boards, as I only have a single rail dc power supply. This will solve the problem perfectly. Thanks John!
Nice one John! That's just what the doctor ordered. I wired up a 386 board with a mic and a speaker(I think I need that board in the video) Installed the mic on the corner of my house and it thwarted two attempts at burglary in two days. The 386 is touchy on the adjustment though but when its tuned its great. Can listen to the birds chirping in the kitchen and my cat loves listening to them too.
Best way to find high power transformers for amplifiers - in broken amplifiers! Who would believe that ;-) Or other things that do amplifier stuff too, like some dvd players with hi-power speaker+woofer output, home cinemas/old big CRT TVs (sometimes)... From the dumpsters, or on ebay/local online or real flea market - for less than their worth in copper, usually.
just wanted to say thank you for teaching us how to hook this up. i ordered this kit due to your recommendation from another video you made and was wondering how i was gonna power the thing after soldering it all together, which led me to this video. success. appreciate it very much. thanks. take care.
TDA 2006 is a dual supply amplifier (simular to the TDA 2030/2050) that I stole from an old CRT TV, and there it was used as a single supply amp? Speaker connected directly to -Vs.
bean fiddling with TDA's and Transistors building little amplifiers and you just blew my mind!!!....Of course we don't the DC split......how come I didn't think of that!!! so simple
2:11 How about a totem pole transistor configuration with pull up/down resistors to split the power rail? ... rather than these resistors. Simulation shows it works fine and current has a return path.
I have a small preamp with the power connection of +12V, 0, -12V A/C that I was able to run just fine without the virtual ground, from a 24V D/C power supply. There is a bridge rectifier close to the power connector so I figured it would work fine with D/C and it seemingly does without any trouble or extra heat or anything. It also seems to have a better noise floor as well with the D/C supply, so no noise when no signal is input.
I probably bought these parts 2 years ago and never made the circuit. Now it all makes perfect sense. I might try to use the dual volt source idea to make a simple guitar amp in a box. Edit: just realized I would be trying to use the 9 Volt pedal supply as 2 sources. That seems like a terrible idea. Maybe I'll get an 18 volt pedal supply
I’m interested in updating a vintage single rail integrated amp with the LM1875 boards. I recapped this amp before considering this. It has a 45 volt B+. While recapping it I upped the the B+ cap from 2000uf to 3800uf and was wondering if the dual supply caps need to be as large as 4700uf or if there is anything else I should consider? This is the late version of the Realistic SA-700 that had an intermittent channel. I have since found the problem but am still interested in this mod. Thank you for all your very educational videos.
Running the dual supply amp boards as single supply, would put its grounds at half the supply voltage and will be an issue with the rest of the amplifier's ground. I think it would be better to run the LM1875 in true single supply mode which would require a board configured as such. I think the LM1875 datasheet shows a single supply schematic.
Yeah I thought of that after posting this. I just ordered the single supply pcb that you reviewed and going to order higher voltage caps and lm1875 for them. Thank you for your quick responds. ruclips.net/video/vZ7oUjUrto0/видео.html @@JohnAudioTech
I am a bit confused. I thought you were showing how to use 1 power supply to power two boards. In a normal setup, could someone just use two 12-0-12 transformers (one each) and make it like a big boy amp? I am new to this so trying to understand. I see the value of a single wall wart connect, but cant see how you connect to two to get stereo ...help :-)
5:30 Different read because of two different resistors tolerance, if you used potentiometer, I believe you gonna get an equal read by adjusting the pot🤔
Can I add two 1k resistors on input because of the noise(one on left channel(adding resistor to white wire) and the other on right(adding resistor to a red wire) ?
Howdy. I wonder if replacing the resistors with 9V zenerdiodes would work ? Yes. The virtual Neutral would sway somewhat but that happenes with the resistors too. However, there would be no resistor leakage. Regards.
What if you use single supply positive connected to both supply ? Example :- we have smps +24 -0 I wanted to understand why cant we use +24 0 +24 ? Will it work ?
@@JohnAudioTech Ah yes, now I see the exact kit you are testing and that it is not a TDA2030A, but an LM1875T for an equally modest $2.03. Equally amazing. But why does the board say TDA2030A and LM1875T? I guess either can be used?
I tested the LM1875 board but also a TDA2030A board and kit. The TDA2030A, 2040, 2050, 2051 and LM1875 use the same pin out and can be used on that board in the LM1875 video. You do have to take into consideration the supply voltage limits and slight changes in component values between the different ICs, but they can work on that board.
John, I have a split supply TDA-2050 stereo power amplifier board with build-in bridge rectifier and 4 x 3300 uF capactors (for both channels). Also I have kind of suitable power transformer with a single 30V (4A) winding without a center tap. I've got an idea to build for that amplifier a rail splitter using LM675 power opamp. That's a typical application for that device and it's shown in the 2013 Rev. of Datasheet for LM675 (Figure 3. Generating a Split Supply From a Single Supply). I have figured out this LM675 rail splitter can be easily assembled on the very same (LM1875) amplifier PCB that you have demonstrated in this video. Some parts would be omited, some - replaced with jumpers and some other - just relocated. And the 0.22 uF capacitor in the output Zobel circuit needs to be connected to a negative rail instead of a ground wire. I've got a question: Could that circuit be connected to a positive rail instead of the negative one? Such connection might be somewhat more convenient on this PCB. And what do you think about this whole idea?
If your TDA2050 board is just the two amplifiers without any other circuitry to cause an imbalance, you can balance the rails with just two resistors. The rail splitter would not be necessary. I made a single supply TDA2050 amp a few months ago. I have a couple videos about it on this channel.
Hi and thank you for this extremely helpful tutorial From what i understand the best mains transformer for a dual power supply is a center tapped one ? i have seen in the web some schematics to get a dual power supply from a single secondary winding What kind of issues i will have from not using a center tapped one ? i like the single transformers best I do not know why
You could use a SPST switch on the battery side if using the rail splitter caps. If you use two batteries for the dual supply, you need the DPST switch to open the rails simultaneously.
JohnAudioTech opening the rails turns off the amplifier since it's not completing the circuit? And I am going to be using around 3 amps per 24 volt battery. I'll get the switch and fiddle around with it. Thank you
A simple rail splitter like this will almost always have an unbalanced ground. Due to biasing and the op amp, slightly more current will probably be pulled from one of the rails. It usually doesn't matter, but if it does matter, could you buffer the ground to lock it in tighter?
PS-John I looked at the board I got from Kitsrus many long years ago and the trace is much smaller and will not handle the current load as well as the trace on the board you are displaying. Best to you in finding some good boards.
Hi John, early on in the video you said you would like to find a source for the boards or even to buy the kit. Many long yars ago I bought four of them from kitsrus but i do not know if the company is still in business. You can buy these also from Qkits in Ontario, and perhaps also from othe vendors. Thank you for the video.
Is there any difference in output power when the amplifier is powered by Single supply and Split supply ? I mean to say that does an amplifier gives more power if operated on Split supply than Single supply ?
If one side was 20 volts and the other dropped to 5 volts, for example, the amp would clip on the 5v side first because of the lower voltage. No harm would be done.
Your videos are one of the best in YT-audio business. I can listen them and enjoy your clear output and movie star voice while jogging. But my question is what was that speaker? It has good sound even through camera mic(or was it lapel..) I take you have made it yourself. How is the crossover? What are the elements? Possibly you have video on that too...
I don't recall the speakers I used without watching the video. If they are the ones with the horn tweeter and port to the left of the tweeter, I made a video about them some months ago.
It is showing the correct readings in the multimeter. When i give the load it is shifting back to the original voltage. And the ground is nil. Any idea why is it hapening ?
Hi, I am looking to power a mono amp with a 36v bicycle battery. So I guess this solution would work for a single battery as well? Do you recommend any single chanel amp that can take 36v supply?
Hello Sir, I need your assistance. I am using some analogue sensors. Am using more than one (12) sensors on a vehicle. I want to aggregate all the voltages from the sensors and give it a single output. Please can you advice or recommend any electrical item that can help me do this please. Thank you
Hi John, I will have to build more than one single rail power supply for the amps I have ordered, please let me know where I can buy the correct resistors and capacitors 1k1w and 4.700 respectively. Thank you for your help.
How well does this work as far as noise and ripple are concerned , im asking as bought a similar kit recently thou was goimg to power it from an 15v ac to ac adapter .
Not sure i understand the 1K. What if you need significant current? I guess the amp pulls its main current through each + / - leg and not through the 1k? But wont it still need to sink the current...i guess the cap gives it an AC sink though. Interesting circuit
Provided the DC current draw is equal on each rail and AC current draw is symmetric over a cycle, the circuit stays balanced. The resistors center the common rail.
Would be viable to use the 12v+ of 2 molex from a pc atx powersupply to feed dual +-12v ac to a circuit? Is there a way? Like uniting both + and gnd from the molex with each other + and gnd respectively and making the virtual ground connection normally like the video?. Or making 2 separate circuits (1 for each molex) and then pairing the + - and virtual gnd of each one in the amp circuit terminal?
That would not work because, relative to ground, both 12v outputs are positive and usually come off the same point inside the supply. ATX supplies have a -12v out but it may be limited in current.
Hi John. Very helpful video, thank you. A question if you don't mind : I have two 10000µF (63 volts) capacitors salvaged from an old receiver. Can I use those instead of the two 4700µF you suggest ?
I use computer PSUs for all my speaker projects, as it provides clean 12v's and loads of amps. Can I safely use this splitter board at higher wattages? I grabbed a cheap _IRS2092S 500W Mono Channel Digital Amplifier Class D_ and a 600w DC upconverter to feed it the 65v it needs. Now I have no way of powering it and I really don't want to spend 3x as much on a dual DC power supply... :^/
You need capacitors that can cope with the voltage at the rails rather than the voltage from the main supply. Your split supply is likely to be +16 / -16 volts, but I would still use 25V capacitors for that scenario. (There are 16v caps, but you would be driving them at their limits and that's not advisable). A 'rule of thumb' I use it to use 2200uf per amp current. If your rails need 1A of current each (or less), then 2200uf is fine. If more than 1A per rail, I'd use the larger caps.
i found an old audio amplifier that i took apart and rescued 3 tda2030av chips. i want to make a 2.1 amp out of it but i only found schematics with dual power supply. can i use 2 3300uf capacitors? hope this works and i will be able to power it with a 12v dc adapter. :D
Hi, i have plans of building an amp out of from two or three bridged lm3886 for each chanel. They need +-28v for full output. I have a Meanwell 48v 600w single rail power supply. Would this work for this application and what values for the caps and restistors should i aim for? The power supply can be adjusted to 55v, which is is near enough the double of 28v.
The amps i'm planing to use are either this www.audiophonics.fr/en/amplifier-boards/audiophonics-apd85-amplifier-module-mono-lm3886-100w-8-ohms-p-4146.html or this www.audiophonics.fr/en/amplifier-boards/audiophonics-apd87-mono-lm3886-amplifier-module-150w-8-ohm-p-4145.html.
Have one question John. What if the Transformer amp is twice as much as needed? But the voltage fits Any solution to that, if so what is it? Like let say you need a dual 12 volts 30 va transformer. But the transformer is dual 12v 60 va. You proberly need a Resistance and a fuse. I just do not get that how Ohm law apply to this, Since the voltage and amp are already given.
Hi john , i have a 48v 2A single power supply, do you think it would be safer to upgrade the two 1k 1W to 1k 5w resistor. as it would disipate heat quicker and stay cooler, am i right?
Let's do the math. You have two 1K resistors connected across the 48v supply to act as balancing resistors, right? If so, they are in series, so it is 2K ohms across 48v. To find the power dissipation, it is the voltage squared divided by the resistance 48^2/2000=1.152w. Each resistor is splitting the dissipation, so each one dissipates 576 milliwatts. This is well within the spec of a 1 watt resistor, so a 5 watt resistor upgrade is not necessary. Now, a split supply can become unbalanced with an uneven load causing more dissipation in one of the resistors. If this happens, the load would not qualify for this type of split power supply anyway.
Assuminf a typical 1W resistor has a max temperature of 150 deg C and that is the temperature it will be at full load (1w). So at 0.58W if we assume it temperature drop is linear, the temp will be 0.58 x 150 or about 87 deg Celsius. As power will be in this resistor all the time the amp is on, it will stay at that temperature. 87DegC is enough to give you a burn. Normally for exposed parts you don't want anything over 65degC. For longevity of the other parts electrolytic capacitors especially you want the temperaturte to be as low as possible. If this is correct, someone (Andrew Dutton more specifically) made me think that a higher power resistor is preferable as it will disipate heat quicker and stay cooler. Also this is considering i'm using a 48v and not a 15or 30v like you did in your video.
If you want to use 5w resistors, then by all means, use them. They will run cooler. At about 60% the rated capacity, the 1w ones will be fine. 1.15 watts won't be an issue for other components on a properly laid out board.
Can this be done with larger amplifiers with larger power needs? I have two 150w amp modules that require dual rail supply.. and i have 48v 350w switch mode power supply so im wondering if something like this can be done on larger amps and power supplies?
In theory it should work. It depends if the amps draw any DC currents from virtual ground to rail to imbalance the VG. Rail splitting a 48v supply gives you +24/-24v which won't provide anywhere near 150w with normal speaker loads. You need two 48v supplies for each rail.
Is the amp a bridged configuration? You would need around 110 volts supply (+/- 55v) to get 150 clean watts from an 8 ohm load or around 80v for 4 ohms for a single ended amp. A bridged configured amp would not need as much supply voltage. Beyond that, the power rating on a lot of amplifier modules are sheer fantasy.
www.aliexpress.com/item/Assembled-150W-150W-HIFI-Audio-Power-Amplifier-Clone-Marantz-MA-9S2-AMP-C5200-A1943/723120945.html?spm=2114.13010708.0.0.zxg86v This is the module i got.. I bought it mainly cause it has enough power for me with very low distortion.. All caps are 63v .. I asked seller if i need center taped transferomed and he replyed "not need, if have will be better" lol
You will need a center tapped transformer or one with two secondaries in order to make a dual supply for this amp. Amps would need +/- 55 volts at full load for that kind of power. 600 VA transformer is recommended for stereo amp. The 63 volt caps you see connect from rail to ground so they don't see the full rail voltage. I have doubts that all of the parts are authentic, so who knows how it will work.
I made a dual supply using two 1K 2Watts resistors and two 4700 capacitors and powered it with 24 Volts 2 Ampere supply but the power output was only 6 watts max before Clipping. I expected atleast 10 Watts
John, excellent video, thank you! However, am I right in thinking that, because of the limited capacity of the caps, low frequencies would distort sooner than high frequencies? It seems to me that low frequencies would move the virtual ground voltage up and down more than higher frequencies.
hey, may i borrow your expertise on an amplifier project that I've been struggling with, somewhat related to this video? the premise is that I have a pair of amp chips, which usually run on 24VAC, but instead, im running them with 2x 24V meanwell DC power supplies, which i am running in series, with a center tap between the two power sources to be my virtual ground. The amp chips work fine, but I've cooked something when trying to connect a low pass filter chip, and/or the aux socket to the amp chip's input terminals. I'm pretty sure that because my virtual ground is at +24v, and the sleeve is true/chassis ground, there is a shorted potential. So, I've added DC blocking capacitors between the socket, and the virtual ground, and another one between the two signal ground terminals, and still, something is cooking. The low pass filter runs off the first power supply for +24 DC power, if that helps. Thank you for reading.
I want to say thank you, i used an LM1875 with an old HP printer power supply (32v, 1560mA) and used your modification to get dual power. It works great, i wonder if i can use it to power up 2x 1875 or if it is too much. My speakers are 6Ω (small ones 2way)
If you like to turn it up loud with a lot of bass, it may be pushing the limit of the supply. Just remember the amp should be isolated from ground since there is 16 volts on the amp's circuit ground.
@@JohnAudioTech I understand. I think i will try and make a real dual voltage power supply with about 40V and 3-4 Amps. I hope this should be enough. Please don't stop making similar videos, i know a lot of people are asking for bluetooth 2.1 videos but i personally would like to see some speaker protection ones with circuits providing a 2-3 second delay, or even some with speaker crossovers. Thanks for all the things i learned from you so far.
@@JohnAudioTech I wanted to give some feedback, i connected the HP power supply (32v, 1560mA) attached to your circuit with the 2x LM1875 and it is working great. I played both of my speakers (good 2way bookself speakers) at high volume for an hour and the power supply doesn't get hot at all (just warm) which is surprising considering it is only a 1560mah power supply. Ofcourse i am not getting maximum RMS but it is very Loud already for my application (computer speakers). You were right about this little amp the sound is crispy, powerful and the bass is great. I get absolutely no hiss sound from the speakers neither any DC crackling sound when i switch on/off the amp. What a nice amplifier!
before I knew about this, I connected the sound to the v+ GND and v- and used dc power into the white connector. I got the speaker output right tho. LOL! So don't do that or else it goes on fire.
Hi jonh i am a fan of your video. Specially those of amps. On a microlab subwoofer i found a non center tapped transformer 2 diodes and 2 caps. There were 2 cable at secondary side. 1 cable was directly connected to one cap's positive and one cap's negetive and one cable was connected through two diodes to other negetive and positive of those cap's. If you understand what I mean. Sorry i am not on my pc so cannot give you the diagram right now. Now my question is this kind of symmetrical power supply is any good for the amp? I mean how the amp perform using this kind of supply? Thanks a lot. Keep up the good work.
If you think about it, in a normal supply, the caps supply the current to the amp because the rectified AC tops them off at the peaks only. The rectifier diodes are reverse biased most of the time, so the transformer is electrically disconnected for the bulk of the cycle. In either case, the caps get worked about the same
A lot to consider. Was wondering what the worst case would be in terms of inrush current and Vmax and the resultant heating due to ESR. Though in your circuit your feeding it with a battery, I keep thinking your feeding it with a raw bridge output. So yeah, a walk in the park.
Thank God you made this video I actually ordered the amplifier based off your recommendation. When it came in I was very confused on how to hook it up. I feel like I'm going down a very deep rabbit hole that has no bottom.
Pm me can you install do sola battery......
No shit. Wtf is a dual supply amplifier? This is not the "they don't really sell power cables thick enough" kind of dual supply i have ever seen or thought about
I had a speaker DAC without power board and repaired like so;
4 zener diodes 12v*2 on negative and 12v*2 on positive, center between 4 diodes is the virtual ground. Used 2 parallels of 1 amp 12v diodes to get 2 amps on each ray and a 24v psu.
If you don't mind the offset, your solution is much more practical!
Great video!
I've been stymied, not being able to test some new amp boards, as I only have a single rail dc power supply. This will solve the problem perfectly. Thanks John!
Nice one John! That's just what the doctor ordered. I wired up a 386 board with a mic and a speaker(I think I need that board in the video) Installed the mic on the corner of my house and it thwarted two attempts at burglary in two days. The 386 is touchy on the adjustment though but when its tuned its great. Can listen to the birds chirping in the kitchen and my cat loves listening to them too.
Best way to find high power transformers for amplifiers - in broken amplifiers!
Who would believe that ;-)
Or other things that do amplifier stuff too, like some dvd players with hi-power speaker+woofer output, home cinemas/old big CRT TVs (sometimes)...
From the dumpsters, or on ebay/local online or real flea market - for less than their worth in copper, usually.
The first sound sample was the best you ever had, John. Great video as allways, thank you!
Pm me can you install do sola battery......
just wanted to say thank you for teaching us how to hook this up. i ordered this kit due to your recommendation from another video you made and was wondering how i was gonna power the thing after soldering it all together, which led me to this video. success. appreciate it very much. thanks. take care.
Pm me can you install do sola battery......
TDA 2006 is a dual supply amplifier (simular to the TDA 2030/2050) that I stole from an old CRT TV, and there it was used as a single supply amp? Speaker connected directly to -Vs.
bean fiddling with TDA's and Transistors building little amplifiers and you just blew my mind!!!....Of course we don't the DC split......how come I didn't think of that!!! so simple
Thanks John this is what I was working for to play with my little power supply project.
OMG Thank You! Thank You!!! i can now power my 60w rms audio amplifier without buying special transformer!!! Thank You alot! This helps me alot!
I love the lab cat 😂😂
2:11 How about a totem pole transistor configuration with pull up/down resistors to split the power rail? ... rather than these resistors.
Simulation shows it works fine and current has a return path.
I have a small preamp with the power connection of +12V, 0, -12V A/C that I was able to run just fine without the virtual ground, from a 24V D/C power supply. There is a bridge rectifier close to the power connector so I figured it would work fine with D/C and it seemingly does without any trouble or extra heat or anything.
It also seems to have a better noise floor as well with the D/C supply, so no noise when no signal is input.
LOL, I have that same RS calculator. The right side pad only works sometimes if you fold it in slightly.
It looks like an exact clone of a Casio fx-451!
Skynet adapter? Is it possible they take it from the terminator movie's 😂😂😂
Sir, all your videos are wonderful & informative. I Love them all :-) :-)
Can I use dual smps to get a negative output please reply 🙏🙏
what if i put two amps on the same circuit??
I probably bought these parts 2 years ago and never made the circuit. Now it all makes perfect sense. I might try to use the dual volt source idea to make a simple guitar amp in a box.
Edit: just realized I would be trying to use the 9 Volt pedal supply as 2 sources. That seems like a terrible idea. Maybe I'll get an 18 volt pedal supply
I’m interested in updating a vintage single rail integrated amp with the LM1875 boards. I recapped this amp before considering this. It has a 45 volt B+. While recapping it I upped the the B+ cap from 2000uf to 3800uf and was wondering if the dual supply caps need to be as large as 4700uf or if there is anything else I should consider?
This is the late version of the Realistic SA-700 that had an intermittent channel. I have since found the problem but am still interested in this mod.
Thank you for all your very educational videos.
Running the dual supply amp boards as single supply, would put its grounds at half the supply voltage and will be an issue with the rest of the amplifier's ground. I think it would be better to run the LM1875 in true single supply mode which would require a board configured as such. I think the LM1875 datasheet shows a single supply schematic.
Yeah I thought of that after posting this. I just ordered the single supply pcb that you reviewed and going to order higher voltage caps and lm1875 for them. Thank you for your quick responds. ruclips.net/video/vZ7oUjUrto0/видео.html @@JohnAudioTech
Can i use 24volts in that??
I am a bit confused. I thought you were showing how to use 1 power supply to power two boards. In a normal setup, could someone just use two 12-0-12 transformers (one each) and make it like a big boy amp? I am new to this so trying to understand. I see the value of a single wall wart connect, but cant see how you connect to two to get stereo ...help :-)
5:30 Different read because of two different resistors tolerance, if you used potentiometer, I believe you gonna get an equal read by adjusting the pot🤔
Thanks I had been wondering how to run this amp board I had got a while back
Never thought I would use it
Can I add two 1k resistors on input because of the noise(one on left channel(adding resistor to white wire) and the other on right(adding resistor to a red wire) ?
Howdy.
I wonder if replacing the resistors with 9V zenerdiodes would work ?
Yes. The virtual Neutral would sway somewhat but that happenes with the resistors too. However, there would be no resistor leakage.
Regards.
is it fine that the center ground isn't 0volt?
can we get the circuit from the module
Thank you for creating this!
Really this is work or not ?
Hello, how many amps does the maximum current pass through this circuit?
What if you use single supply positive connected to both supply ?
Example :- we have smps +24 -0
I wanted to understand why cant we use +24 0 +24 ?
Will it work ?
Can we connect two 12 Volt 2 Ampere smps supply in series to make dual supply for powering this type of boards ? Will there be any problem ?
You can get a TDA2030A kit, similar to what is seen on this video, for the modest sum of $1.22, shipping included. Rather amazing.
I tested a couple of these and they weren't that good.
@@JohnAudioTech Ah yes, now I see the exact kit you are testing and that it is not a TDA2030A, but an LM1875T for an equally modest $2.03. Equally amazing. But why does the board say TDA2030A and LM1875T? I guess either can be used?
I tested the LM1875 board but also a TDA2030A board and kit. The TDA2030A, 2040, 2050, 2051 and LM1875 use the same pin out and can be used on that board in the LM1875 video. You do have to take into consideration the supply voltage limits and slight changes in component values between the different ICs, but they can work on that board.
John, I have a split supply TDA-2050 stereo power amplifier board with build-in bridge rectifier and 4 x 3300 uF capactors (for both channels). Also I have kind of suitable power transformer with a single 30V (4A) winding without a center tap. I've got an idea to build for that amplifier a rail splitter using LM675 power opamp. That's a typical application for that device and it's shown in the 2013 Rev. of Datasheet for LM675 (Figure 3. Generating a Split Supply From a Single Supply). I have figured out this LM675 rail splitter can be easily assembled on the very same (LM1875) amplifier PCB that you have demonstrated in this video. Some parts would be omited, some - replaced with jumpers and some other - just relocated. And the 0.22 uF capacitor in the output Zobel circuit needs to be connected to a negative rail instead of a ground wire. I've got a question: Could that circuit be connected to a positive rail instead of the negative one? Such connection might be somewhat more convenient on this PCB.
And what do you think about this whole idea?
If your TDA2050 board is just the two amplifiers without any other circuitry to cause an imbalance, you can balance the rails with just two resistors. The rail splitter would not be necessary. I made a single supply TDA2050 amp a few months ago. I have a couple videos about it on this channel.
Hi and thank you for this extremely helpful tutorial From what i understand the best mains transformer for a dual power supply is a center tapped one ? i have seen in the web some schematics to get a dual power supply from a single secondary winding
What kind of issues i will have from not using a center tapped one ? i like the single transformers best I do not know why
What are the DPST switches used for? I am going to do this with batteries. I need switches ?
You could use a SPST switch on the battery side if using the rail splitter caps. If you use two batteries for the dual supply, you need the DPST switch to open the rails simultaneously.
JohnAudioTech opening the rails turns off the amplifier since it's not completing the circuit? And I am going to be using around 3 amps per 24 volt battery. I'll get the switch and fiddle around with it. Thank you
A simple rail splitter like this will almost always have an unbalanced ground. Due to biasing and the op amp, slightly more current will probably be pulled from one of the rails. It usually doesn't matter, but if it does matter, could you buffer the ground to lock it in tighter?
PS-John I looked at the board I got from Kitsrus many long years ago and the trace is much smaller and will not handle the current load as well as the trace on the board you are displaying. Best to you in finding some good boards.
Excellent video. Really informative!
Hi John, early on in the video you said you would like to find a source for the boards or even to buy the kit. Many long yars ago I bought four of them from kitsrus but i do not know if the company is still in business. You can buy these also from Qkits in Ontario, and perhaps also from othe vendors. Thank you for the video.
1k 1w resistor. Does it matter from the voltage. How big and what kind of resistor to use. Also the amperage.
Is there any difference in output power when the amplifier is powered by Single supply and Split supply ?
I mean to say that does an amplifier gives more power if operated on Split supply than Single supply ?
How would that dual power supply look without the board, just using the components?
Very helpful! What would happen to the chip, if one side of the supply gets faulty or gets unbalanced a lot.
If one side was 20 volts and the other dropped to 5 volts, for example, the amp would clip on the 5v side first because of the lower voltage. No harm would be done.
I have a 62V DC 5A adapter ... After split what do you think i will get out of it ? And what audio kit will get most of it ?
wouldn't the 1k resistors be dependent on the current draw?
Do you think this would work on a synth that needs -v, I had used a buck converter but it was too much noise. The schimatic says it need 12+-v 500ma.
Your videos are one of the best in YT-audio business. I can listen them and enjoy your clear output and movie star voice while jogging. But my question is what was that speaker? It has good sound even through camera mic(or was it lapel..) I take you have made it yourself. How is the crossover? What are the elements?
Possibly you have video on that too...
I don't recall the speakers I used without watching the video. If they are the ones with the horn tweeter and port to the left of the tweeter, I made a video about them some months ago.
I can use this scheme also for power up a dual rail analog switch? Like the MAX4678?
Can I power a single supply amp with a dual supply?(+ input into live terminal and - input into neutral terminal)?
It is showing the correct readings in the multimeter. When i give the load it is shifting back to the original voltage. And the ground is nil. Any idea why is it hapening ?
so, if I have 48v power supply, and i want to drive the amplifier that need at least 5A, what is the best value for the resistor
Hi, I am looking to power a mono amp with a 36v bicycle battery. So I guess this solution would work for a single battery as well? Do you recommend any single chanel amp that can take 36v supply?
Can I use this for TDA 2030 based amps?
It's work's for TDA2030 AMPLIFIER CIRCUIT ?
Hello Sir,
I need your assistance. I am using some analogue sensors. Am using more than one (12) sensors on a vehicle. I want to aggregate all the voltages from the sensors and give it a single output.
Please can you advice or recommend any electrical item that can help me do this please. Thank you
Look up "summing amplifier circuit".
@@JohnAudioTech thanks alot and would look it up ASAP
Hi John, I will have to build more than one single rail power supply for the amps I have ordered, please let me know where I can buy the correct resistors and capacitors 1k1w and 4.700 respectively. Thank you for your help.
Can i use that on the 12v car battery?
How well does this work as far as noise and ripple are concerned , im asking as bought a similar kit recently thou was goimg to power it from an 15v ac to ac adapter .
You need to convert the AC to DC and use at least 6800uf capacitors to reduce the ripple.
JohnAudioTech Thankyou very much :-)
Good day sir is there a way to power ac gnd ac using batteries or 12v power supply? Thank you
Sir can I do that on ac single 12 volts ac turn into 2 12volts ac?
Does VG connect between the two 1K resistors? I cannot make out if there is a dot where the wires cross.
Yes it connects.
Not sure i understand the 1K. What if you need significant current? I guess the amp pulls its main current through each + / - leg and not through the 1k? But wont it still need to sink the current...i guess the cap gives it an AC sink though. Interesting circuit
Provided the DC current draw is equal on each rail and AC current draw is symmetric over a cycle, the circuit stays balanced. The resistors center the common rail.
Would be viable to use the 12v+ of 2 molex from a pc atx powersupply to feed dual +-12v ac to a circuit? Is there a way? Like uniting both + and gnd from the molex with each other + and gnd respectively and making the virtual ground connection normally like the video?. Or making 2 separate circuits (1 for each molex) and then pairing the + - and virtual gnd of each one in the amp circuit terminal?
That would not work because, relative to ground, both 12v outputs are positive and usually come off the same point inside the supply. ATX supplies have a -12v out but it may be limited in current.
Hi John. Very helpful video, thank you. A question if you don't mind : I have two 10000µF (63 volts) capacitors salvaged from an old receiver. Can I use those instead of the two 4700µF you suggest ?
Yes, those would actually be better.
JohnAudioTech Nice! Thank you.
I use computer PSUs for all my speaker projects, as it provides clean 12v's and loads of amps. Can I safely use this splitter board at higher wattages? I grabbed a cheap _IRS2092S 500W Mono Channel Digital Amplifier Class D_ and a 600w DC upconverter to feed it the 65v it needs. Now I have no way of powering it and I really don't want to spend 3x as much on a dual DC power supply... :^/
If i'll use a 32V 1.5A supply, do I need to use 35V capacitors or can I use 25V capacitors? What are the cons if I use 2200uF instead of 4700uF?
You need capacitors that can cope with the voltage at the rails rather than the voltage from the main supply.
Your split supply is likely to be +16 / -16 volts, but I would still use 25V capacitors for that scenario.
(There are 16v caps, but you would be driving them at their limits and that's not advisable).
A 'rule of thumb' I use it to use 2200uf per amp current. If your rails need 1A of current each (or less), then 2200uf is fine.
If more than 1A per rail, I'd use the larger caps.
Thank you so much for your reply :)
Hi John, it might be oversized, but what about using cheap audio amps like the TDA2030 as railsplitter?
That is fine if you need to balance the virtual ground due to DC loads from ground to a rail. The amp in my test didn't need balancing.
Will this work with tda7293 100w amp module from ebay
I have a board that requires three rail ac supply. I have a 28vac transformer. is there a way to make it a 14-0-14 ac ?
you can re--build the transformer, or easier just to buy another
Immediately thumbs-upped the cat hell yeah
i found an old audio amplifier that i took apart and rescued 3 tda2030av chips. i want to make a 2.1 amp out of it but i only found schematics with dual power supply. can i use 2 3300uf capacitors? hope this works and i will be able to power it with a 12v dc adapter. :D
Hi, i have plans of building an amp out of from two or three bridged lm3886 for each chanel. They need +-28v for full output. I have a Meanwell 48v 600w single rail power supply. Would this work for this application and what values for the caps and restistors should i aim for? The power supply can be adjusted to 55v, which is is near enough the double of 28v.
The amps i'm planing to use are either this www.audiophonics.fr/en/amplifier-boards/audiophonics-apd85-amplifier-module-mono-lm3886-100w-8-ohms-p-4146.html
or this www.audiophonics.fr/en/amplifier-boards/audiophonics-apd87-mono-lm3886-amplifier-module-150w-8-ohm-p-4145.html.
Hi John. I have a 120 volts and want the output to be 60 volts each. Can you tell me the value of capacitor and wattage of resistor to be used..Thanks
what you have 120V where do you get these from? and what the heck do you plan to do with them?
Have one question John. What if the Transformer amp is twice as much as needed?
But the voltage fits
Any solution to that, if so what is it?
Like let say you need a dual 12 volts 30 va transformer. But the transformer is dual 12v 60 va.
You proberly need a Resistance and a fuse. I just do not get that how Ohm law apply to this, Since the voltage and amp are already given.
Higher current is fine. The amp draws only the current it needs.
Oh Great thx for the answer
Can this arrangement give the maximum output of tda2030 as in split supply?
Yes. Be sure to use large value capacitors so bass remains strong.
Hi john , i have a 48v 2A single power supply, do you think it would be safer to upgrade the two 1k 1W to 1k 5w resistor. as it would disipate heat quicker and stay cooler, am i right?
Let's do the math. You have two 1K resistors connected across the 48v supply to act as balancing resistors, right? If so, they are in series, so it is 2K ohms across 48v. To find the power dissipation, it is the voltage squared divided by the resistance 48^2/2000=1.152w. Each resistor is splitting the dissipation, so each one dissipates 576 milliwatts. This is well within the spec of a 1 watt resistor, so a 5 watt resistor upgrade is not necessary. Now, a split supply can become unbalanced with an uneven load causing more dissipation in one of the resistors. If this happens, the load would not qualify for this type of split power supply anyway.
Assuminf a typical 1W resistor has a max temperature of 150 deg C and that is the temperature it will be at full load (1w). So at 0.58W if we assume it temperature drop is linear, the temp will be 0.58 x 150 or about 87 deg Celsius. As power will be in this resistor all the time the amp is on, it will stay at that temperature. 87DegC is enough to give you a burn. Normally for exposed parts you don't want anything over 65degC. For longevity of the other parts electrolytic capacitors especially you want the temperaturte to be as low as possible. If this is correct, someone (Andrew Dutton more specifically) made me think that a higher power resistor is preferable as it will disipate heat quicker and stay cooler. Also this is considering i'm using a 48v and not a 15or 30v like you did in your video.
If you want to use 5w resistors, then by all means, use them. They will run cooler. At about 60% the rated capacity, the 1w ones will be fine. 1.15 watts won't be an issue for other components on a properly laid out board.
ok i might be a bit overprotectionist then.. thx for sharing your knowledge. priceless
Can you Bridge these Boards ?
Pm me can you install do sola battery......
Can this be done with larger amplifiers with larger power needs? I have two 150w amp modules that require dual rail supply.. and i have 48v 350w switch mode power supply so im wondering if something like this can be done on larger amps and power supplies?
In theory it should work. It depends if the amps draw any DC currents from virtual ground to rail to imbalance the VG. Rail splitting a 48v supply gives you +24/-24v which won't provide anywhere near 150w with normal speaker loads. You need two 48v supplies for each rail.
Well if im not wrong with 2x48v supplys connected in series , voltage betwen + and - would be way more than any component on the amp module can handle
Is the amp a bridged configuration? You would need around 110 volts supply (+/- 55v) to get 150 clean watts from an 8 ohm load or around 80v for 4 ohms for a single ended amp. A bridged configured amp would not need as much supply voltage. Beyond that, the power rating on a lot of amplifier modules are sheer fantasy.
www.aliexpress.com/item/Assembled-150W-150W-HIFI-Audio-Power-Amplifier-Clone-Marantz-MA-9S2-AMP-C5200-A1943/723120945.html?spm=2114.13010708.0.0.zxg86v
This is the module i got.. I bought it mainly cause it has enough power for me with very low distortion..
All caps are 63v .. I asked seller if i need center taped transferomed and he replyed "not need, if have will be better" lol
You will need a center tapped transformer or one with two secondaries in order to make a dual supply for this amp. Amps would need +/- 55 volts at full load for that kind of power. 600 VA transformer is recommended for stereo amp. The 63 volt caps you see connect from rail to ground so they don't see the full rail voltage. I have doubts that all of the parts are authentic, so who knows how it will work.
Someone likes his chewy bars.
Hello sir. My amplifier board needs 12 v dual power supply. How it works using 12 v battery
You would need two 12v batteries or a switchmode power supply that provides the dual voltages.
I made a dual supply using two 1K 2Watts resistors and two 4700 capacitors and powered it with 24 Volts 2 Ampere supply but the power output was only 6 watts max before Clipping. I expected atleast 10 Watts
Really man, you saved my life. But, could I use those on three(or four) TDA7293s on parallel mode? Use 10,000uf caps? 5w resistors?
John, excellent video, thank you! However, am I right in thinking that, because of the limited capacity of the caps, low frequencies would distort sooner than high frequencies? It seems to me that low frequencies would move the virtual ground voltage up and down more than higher frequencies.
Exactly. You want to use large caps when doing this. Same size as a normal supply. 10mf is what I use for a small stereo amp.
JohnAudioTech can I use a TDA2050 to stabilize the virtual ground ?
hey, may i borrow your expertise on an amplifier project that I've been struggling with, somewhat related to this video? the premise is that I have a pair of amp chips, which usually run on 24VAC, but instead, im running them with 2x 24V meanwell DC power supplies, which i am running in series, with a center tap between the two power sources to be my virtual ground. The amp chips work fine, but I've cooked something when trying to connect a low pass filter chip, and/or the aux socket to the amp chip's input terminals. I'm pretty sure that because my virtual ground is at +24v, and the sleeve is true/chassis ground, there is a shorted potential. So, I've added DC blocking capacitors between the socket, and the virtual ground, and another one between the two signal ground terminals, and still, something is cooking. The low pass filter runs off the first power supply for +24 DC power, if that helps. Thank you for reading.
solved it! had the low pass filter on the negative rail and also had to ground the center node between the two power sources. now it works great!
I want to say thank you, i used an LM1875 with an old HP printer power supply (32v, 1560mA) and used your modification to get dual power. It works great, i wonder if i can use it to power up 2x 1875 or if it is too much. My speakers are 6Ω (small ones 2way)
If you like to turn it up loud with a lot of bass, it may be pushing the limit of the supply. Just remember the amp should be isolated from ground since there is 16 volts on the amp's circuit ground.
@@JohnAudioTech I understand. I think i will try and make a real dual voltage power supply with about 40V and 3-4 Amps. I hope this should be enough.
Please don't stop making similar videos, i know a lot of people are asking for bluetooth 2.1 videos but i personally would like to see some speaker protection ones with circuits providing a 2-3 second delay, or even some with speaker crossovers. Thanks for all the things i learned from you so far.
@@JohnAudioTech I wanted to give some feedback, i connected the HP power supply (32v, 1560mA) attached to your circuit with the 2x LM1875 and it is working great. I played both of my speakers (good 2way bookself speakers) at high volume for an hour and the power supply doesn't get hot at all (just warm) which is surprising considering it is only a 1560mah power supply. Ofcourse i am not getting maximum RMS but it is very Loud already for my application (computer speakers).
You were right about this little amp the sound is crispy, powerful and the bass is great. I get absolutely no hiss sound from the speakers neither any DC crackling sound when i switch on/off the amp. What a nice amplifier!
when you say it is an ac circuit, Do you mean if I was to get one of these boards I could power it strait from wall outlet ?
No, this is a DC supplied circuit. The signal that passes through to the output must be AC to keep the virtual ground voltage centered properly.
It is an AC circuit because the audio amplifier outputs AC voltage to the speakers.
At 6:55 that's a charger for a T-800!
It's made by Skynet....
before I knew about this, I connected the sound to the v+ GND and v- and used dc power into the white connector. I got the speaker output right tho. LOL! So don't do that or else it goes on fire.
Great work what I need thanx.
Isn’t this work without resistors??
@Popeye works great with combination of two power source..
AC/DC was so much better than that jazz crap
The video was about AC and DC
What is that song?
plz make a video on tda 7388
watts about plz?
Hi jonh i am a fan of your video. Specially those of amps. On a microlab subwoofer i found a non center tapped transformer 2 diodes and 2 caps. There were 2 cable at secondary side. 1 cable was directly connected to one cap's positive and one cap's negetive and one cable was connected through two diodes to other negetive and positive of those cap's. If you understand what I mean. Sorry i am not on my pc so cannot give you the diagram right now. Now my question is this kind of symmetrical power supply is any good for the amp? I mean how the amp perform using this kind of supply? Thanks a lot. Keep up the good work.
It would be more effective to have two PSU's in series for your +/- voltage. Just make sure to unground them from the mains so they are floating.
Thankyou
A good pair of caps is key here, they will be getting worked..
If you think about it, in a normal supply, the caps supply the current to the amp because the rectified AC tops them off at the peaks only. The rectifier diodes are reverse biased most of the time, so the transformer is electrically disconnected for the bulk of the cycle. In either case, the caps get worked about the same
A lot to consider. Was wondering what the worst case would be in terms of inrush current and Vmax and the resultant heating due to ESR. Though in your circuit your feeding it with a battery, I keep thinking your feeding it with a raw bridge output. So yeah, a walk in the park.