Hi guys!!!
Please I need your support!!!
I've a small amplifier circuit based on the old TBA810...this circuit is very similar to this one:
http://golbornevintageradio.co.uk/forum/attachment.php?aid=10105
I'd like to replace the small TBA810 with this IC (in order to get more power):
783p ... - Datasheet Search Engine Download
However there's a problem: the MA783 Faichild IC works only with 8 and 16 ohm, but I've to use it with 4 ohm speakers.
Is it possible make it suitable also with 4 ohm speakers with some modifications?
Please help me...I'd like so much get it!!!Could you help me?😉
Thank you!
Regards
Pietro
Please I need your support!!!
I've a small amplifier circuit based on the old TBA810...this circuit is very similar to this one:
http://golbornevintageradio.co.uk/forum/attachment.php?aid=10105
I'd like to replace the small TBA810 with this IC (in order to get more power):
783p ... - Datasheet Search Engine Download
However there's a problem: the MA783 Faichild IC works only with 8 and 16 ohm, but I've to use it with 4 ohm speakers.
Is it possible make it suitable also with 4 ohm speakers with some modifications?
Please help me...I'd like so much get it!!!Could you help me?😉
Thank you!
Regards
Pietro
The data sheet shows the 738 handling 4 ohm loads up to 18 volt supply.
I did not check if the pin out and components make it a drop in replacement.
If the 810s are working, leave them alone. There will not be much of a difference at a given supply voltage.
I did not check if the pin out and components make it a drop in replacement.
If the 810s are working, leave them alone. There will not be much of a difference at a given supply voltage.
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Agree: power out depends strictly on power supply voltage.
If you don't rise it, changing the chipamp is useless.
If you don't rise it, changing the chipamp is useless.
Hi guys!http://www.diyaudio.com/forums/chip-amps/263848-replace-tba810-ma783.html#post4100448
First of all I want thank you for your reply!...you're very kind.
Don't worry about the power supply voltage:I had already thought to raise the supply voltage to 24 volts,but I forgot to specify this important detail in my post.
Don't worry about all the indispensable modifications of components that the power supply voltage change involves...that is not a problem because, luckily, I can count on the support and on the help of a expert technician (a dear friend).
I need "only" your precious theoretical support.
So I hope you give me your foundamental help.
Thank you.
Ciao
Pietro
First of all I want thank you for your reply!...you're very kind.
Don't worry about the power supply voltage:I had already thought to raise the supply voltage to 24 volts,but I forgot to specify this important detail in my post.
Don't worry about all the indispensable modifications of components that the power supply voltage change involves...that is not a problem because, luckily, I can count on the support and on the help of a expert technician (a dear friend).
I need "only" your precious theoretical support.
So I hope you give me your foundamental help.
Thank you.
Ciao
Pietro
The TBA810 max supply voltage is 20 volts and the MA783 can't support 4 Ohms above 18 volts (you did want 4 Ohm loads, right?) and is pretty much maxed out at 8 ohm loads @ 24v. Even if they could handle this, the heat sinks would be too small.
You really need to ditch this idea and look at a higher power solution. The LM1875 on 24 volts (+/- 12v split supply or 24v single) will get you around 11 watts of clean power into 4 Ohms or you could run it at +/- 18 volts into the same load for a clean 24 watts.
With, a 16v supply and 8 Ohm loads, the amp you have now would be giving you around 4 clean watts, at 12v less than 2 watts.
You really need to ditch this idea and look at a higher power solution. The LM1875 on 24 volts (+/- 12v split supply or 24v single) will get you around 11 watts of clean power into 4 Ohms or you could run it at +/- 18 volts into the same load for a clean 24 watts.
With, a 16v supply and 8 Ohm loads, the amp you have now would be giving you around 4 clean watts, at 12v less than 2 watts.
Hi Jonhr66!!!
Thank you so much for your help, first of all.
Don't wory about the heat sinks, I already knew that I needed to replace them along with many other components of this circuit.For this reason, any and every possible change, modification or replacement will not be a problem...unless that change, modification or replacement doesn't involve the redesign of the original entire circuit.
Am I wrong or isn't the LM1875 compatible pin to pin with the TBA810?
In this case, using the LM1875 will be impossible for me, unfortunately.
So I've two possibilities: to replace the TBA810 with the compatible TCA940 (but it gives 10 watt with a 10% of distortion!!!mmhhh it's a bad value for my ears!🙁) or I could use the mA783 at 18 volt in order to make it compatible with the 4 ohm.
In this case (using it at 18 volt), could you tell me how many watt the mA783 gives?
Anyway if you know other possible (compatible pin to pin) alternative to the old TBA810...could you suggest it, please?😉
Thank you so much for your immense kindness and patience!!! your help is very precious for me!🙂
Ciao
Pietro
The TBA810 is an obsolete chip amp, and out of production for many years (think 20 or more) and chipamp design took a very different path after Bruno Murari's revolutionary invention of the TO220 , 5 leg chipamp (TDA2002).
So no modern chip matches TBA810 pinout.
The one you found, also obsolete, matches it only because it was probably a "me too" design , a copy of a (way back then) successful product to capture some sales.
If you are ready to build a new PSU, you might go all the way and also build a new chipamp.
LM1875 or one of TDA20xx will do fine.
So no modern chip matches TBA810 pinout.
The one you found, also obsolete, matches it only because it was probably a "me too" design , a copy of a (way back then) successful product to capture some sales.
If you are ready to build a new PSU, you might go all the way and also build a new chipamp.
LM1875 or one of TDA20xx will do fine.
The 10% distortion figure of the TCA940 is because it props up the power output figure. It is a useless way to rate an amp in my opinion. If you look at the datasheet carefully you will see that it can produce up to 5 watts into a 4 Ohm load at 18v supply at .3% THD. It will be about the same as the TBA810 & MA783. Just stick with the original ICs, boost the voltage to 16 or 17 volts (or 18v if you want to push the limit).
JMFahey is right. These are old chips, brought to the market around 40 years ago and discontinued many years ago. The LM1875 will require a new board but is an easy first amp to build and the power & audio quality will leave those old ICs in the dust. If the old amp board has tone controls, you could take the output and route it to the LM1875 input.
JMFahey is right. These are old chips, brought to the market around 40 years ago and discontinued many years ago. The LM1875 will require a new board but is an easy first amp to build and the power & audio quality will leave those old ICs in the dust. If the old amp board has tone controls, you could take the output and route it to the LM1875 input.
Thank you again, guys!
I would like to conclude this thread, asking you my last question because I've the tremendous fear to annoy you excessively, although I must to admit that this topic is very...very..interesting and intriguing for me!!!😉However, at the same time, I'm conscious it could be tiring and galling for you, so I'll limit myself to ask a last question and then I leave you in peace!!!😀.
I already know that maintaining unvaried the current supply voltage (16 volt), I will not get any change of output power even if I used other amp chips (like the aforementioned TCA940 and the mA783).
For this reason, I wanted to replace the small TBA810 with its bigger brother, the TCA940 (they're really brothers) increasing the voltage from 16 volts to 22 or 24 volt (it's the maximum voltage for the TCA940).
In this case, I should get real benefits going from 4 watts per channel to 10 watts per channel.
Obviously, I also know that this change of amp chips will involve the replacement of many components of the circuit.
However, this will not be a problem because this little circuit contains only a few electronic components.
The TBA810 and TCA940 are identical and pin for pin compatibl, in fact they're, as I already said, really brothers: the TCA940 was intoducted on the market, only a few years after the TBA810 (in the 1974), in order to get more power than the TBA810 but leaving unchanged the general architecture of the circuit (as you can notice, I've studied a lot!😀).
In this case, is that a viable option in your opinion?...it's my last possibility, because I can't rebuilt a new circuit and I wouldn't like to change completely the original design of the circuit.
Thank you my friends...you can't imagine how you're helping me!🙂😉
Ciao!
I would like to conclude this thread, asking you my last question because I've the tremendous fear to annoy you excessively, although I must to admit that this topic is very...very..interesting and intriguing for me!!!😉However, at the same time, I'm conscious it could be tiring and galling for you, so I'll limit myself to ask a last question and then I leave you in peace!!!😀.
I already know that maintaining unvaried the current supply voltage (16 volt), I will not get any change of output power even if I used other amp chips (like the aforementioned TCA940 and the mA783).
For this reason, I wanted to replace the small TBA810 with its bigger brother, the TCA940 (they're really brothers) increasing the voltage from 16 volts to 22 or 24 volt (it's the maximum voltage for the TCA940).
In this case, I should get real benefits going from 4 watts per channel to 10 watts per channel.
Obviously, I also know that this change of amp chips will involve the replacement of many components of the circuit.
However, this will not be a problem because this little circuit contains only a few electronic components.
The TBA810 and TCA940 are identical and pin for pin compatibl, in fact they're, as I already said, really brothers: the TCA940 was intoducted on the market, only a few years after the TBA810 (in the 1974), in order to get more power than the TBA810 but leaving unchanged the general architecture of the circuit (as you can notice, I've studied a lot!😀).
In this case, is that a viable option in your opinion?...it's my last possibility, because I can't rebuilt a new circuit and I wouldn't like to change completely the original design of the circuit.
Thank you my friends...you can't imagine how you're helping me!🙂😉
Ciao!
Since 24 volts is the maximum operating voltage on the TCA940, I'd go no higher than 20 volts. The problem is maintaining the supply voltage under full load and not allowing the supply voltage to exceed 24 volts under light load. You'd need a hefty supply for 2 channels. Working in such a tight window, even a regulated supply may be needed. Also you really can't run it with a 4 ohm load over 20v. I wouldn't go above 18v unless you use an 8 ohm speaker. Even with a good heat sink those tabbed DIP packages are not that great at getting rid of the heat from the chip.
Because of the marginal gain, heat and load impedance issues, it seems to be a waste of time to go through with the "upgrade". Being a DIY community, I still recommend a much stronger chip amp (LM1875) or just leave it alone. But heck, it can't be a lot of money, just go ahead in drop in the TCA chip and components and run it with 4 ohm loads at 22 volts. You will get more power, but don't count on the amplifier lasting.
Because of the marginal gain, heat and load impedance issues, it seems to be a waste of time to go through with the "upgrade". Being a DIY community, I still recommend a much stronger chip amp (LM1875) or just leave it alone. But heck, it can't be a lot of money, just go ahead in drop in the TCA chip and components and run it with 4 ohm loads at 22 volts. You will get more power, but don't count on the amplifier lasting.
Hi dear Johnr66!🙂
You've really convinced me!
If you see my photo album, you will notice that I have uploaded several photos of the entire circuit.
I have also uploaded the image of the black frontal panel in order to identify easily the function of each slider.
As you will notice, there is only one unified tone control for each channel (neither bass nor treble separeted control, but only one tone control for channel!).
Next to the headphone's imput, there's a switch to divert the sound to the headphones or to the speakers.
The yellow wires are for the power supply, while the other four (the bigger ones) wires (two blacks, one white, one red) are for the speakers; the transparent cable (the one in which we see the screen of copper) is connected to sources selector (you can see the knobs of each source, including the mono/stereo knob in the photo of the frontal panel).
Do you think that it's possible to use only the preamp circuit removing the final circuit?...as you've recommend me, I would use only the preamp circuit and add a new amplifier circuit (I own several good amplifier circuits without tone controls). I believe that after seeing the picture, you can tell me if a similar modification on this circuit is realizable or not.
I hope you can give me the final opinion...as you can notice, unfortunately I can count only on your (precious) support.
Please help me!!!😉
I spent almost four hours to take the pictures and to upload them here!!!😱...It has been terrible!!!
Thank you again!!!
Ciao!!!
Pietro
P.S.:I apologize for my terrible english but above of all I apologize for the trouble that I'm causing you...unfortunately I'm alone in this project...you can imagine how much I appreciate all you're doing for me!😉
You've really convinced me!
If you see my photo album, you will notice that I have uploaded several photos of the entire circuit.
I have also uploaded the image of the black frontal panel in order to identify easily the function of each slider.
As you will notice, there is only one unified tone control for each channel (neither bass nor treble separeted control, but only one tone control for channel!).
Next to the headphone's imput, there's a switch to divert the sound to the headphones or to the speakers.
The yellow wires are for the power supply, while the other four (the bigger ones) wires (two blacks, one white, one red) are for the speakers; the transparent cable (the one in which we see the screen of copper) is connected to sources selector (you can see the knobs of each source, including the mono/stereo knob in the photo of the frontal panel).
Do you think that it's possible to use only the preamp circuit removing the final circuit?...as you've recommend me, I would use only the preamp circuit and add a new amplifier circuit (I own several good amplifier circuits without tone controls). I believe that after seeing the picture, you can tell me if a similar modification on this circuit is realizable or not.
I hope you can give me the final opinion...as you can notice, unfortunately I can count only on your (precious) support.
Please help me!!!😉
I spent almost four hours to take the pictures and to upload them here!!!😱...It has been terrible!!!
Thank you again!!!
Ciao!!!
Pietro
P.S.:I apologize for my terrible english but above of all I apologize for the trouble that I'm causing you...unfortunately I'm alone in this project...you can imagine how much I appreciate all you're doing for me!😉
ohhhh my Gooooooooooood!!!!!!!!!You're right!!!
I'm very sorry...I forget always something important!!!🙁
In this case, I forgot to specify that you can see the picture on my "public profile"!!!
Here's you can see the photos:
Peters8 Gallery - My Photo Gallery
There're two pages of picture.
I hope you can give me your important opinion!!!😉
I'm very sorry...I forget always something important!!!🙁
In this case, I forgot to specify that you can see the picture on my "public profile"!!!
Here's you can see the photos:
Peters8 Gallery - My Photo Gallery
There're two pages of picture.
I hope you can give me your important opinion!!!😉
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You can take the signal that would normally enter the IC and route it to your new amplifier. It appears to be a passive circuit (aside from the ICs) and won't need power. You would have to reroute output from the new amp back to the board if you want the headphone port to work. You should remove the IC and associated components that can effect the new amplifier.
Wow...thnak you!!!...I'm very happy!!!🙂😉.
Thank to your precious support, finally, I can start to work on this project...it's a "little-big dream" for me and I hope to have even a little bit of luck!!!
In fact, lately in my life I haven't had any luck and any happiness due to an acute desease ... so I hope this project will give me a bit of relaxation, fun and serenity...but this is another story!🙁
It would be better to return to our interesting discussion!!!
Could you confirm if these steps are correct or not?: first of all, I have to disconnect the entire amp circuit with the two TBA810 desoldering it from the other circuit, I mean the one with the sliders for the tone control, the volume and the VU-meter.
Then I can connect the new amplifier circuit to the preamplifier circuit (obviously when I'll decide wich amp IC I've to use for this project!!!).
To do this, I must use the contacts from which I previously desoldered the old amplifier circuit.
To be more specific, could you confirm (looking the picture below) if these contacts are the same contacts you can see in the upper part of the circuit?:
Small amplifier circuit with TBA810 - My Photo Gallery
More precisely: I'm referring to the first row (in the top of the circuit of this picture) formed by a first pair of contacts (in correspondence of the white plastic piece of the vu-meter), then by another pair of contacts (in the middle) and by a final series of three contacts.
If you confirm for me what I asked you, I will start to work alone, leaving you in your deserved peace!🙂😀😉
Thank you for the happiness that your support and collaboration is giving me!😉
Ciao
😉.Thank to your precious support, finally, I can start to work on this project...it's a "little-big dream" for me and I hope to have even a little bit of luck!!!
In fact, lately in my life I haven't had any luck and any happiness due to an acute desease ... so I hope this project will give me a bit of relaxation, fun and serenity...but this is another story!🙁
It would be better to return to our interesting discussion!!!
Could you confirm if these steps are correct or not?: first of all, I have to disconnect the entire amp circuit with the two TBA810 desoldering it from the other circuit, I mean the one with the sliders for the tone control, the volume and the VU-meter.
Then I can connect the new amplifier circuit to the preamplifier circuit (obviously when I'll decide wich amp IC I've to use for this project!!!).
To do this, I must use the contacts from which I previously desoldered the old amplifier circuit.
To be more specific, could you confirm (looking the picture below) if these contacts are the same contacts you can see in the upper part of the circuit?:
Small amplifier circuit with TBA810 - My Photo Gallery
More precisely: I'm referring to the first row (in the top of the circuit of this picture) formed by a first pair of contacts (in correspondence of the white plastic piece of the vu-meter), then by another pair of contacts (in the middle) and by a final series of three contacts.
If you confirm for me what I asked you, I will start to work alone, leaving you in your deserved peace!🙂😀😉
Thank you for the happiness that your support and collaboration is giving me!😉
Ciao
Please John!!! give me your last help!!!
Don't leave me alone...please!!!😉
Then I'll leave you in peace!!!it's a promise!!!🙂
Regards.
Pietro
Don't leave me alone...please!!!😉
Then I'll leave you in peace!!!it's a promise!!!🙂
Regards.
Pietro
hello.
my opinion........
a) this is a working design - leave it as it is. you can upgrade the power supply unit (bigger electrolytic cap and transformer),the sound could have more punch after this tuning.......
b) simply: connect another amp with your headphone jack......
my opinion........
a) this is a working design - leave it as it is. you can upgrade the power supply unit (bigger electrolytic cap and transformer),the sound could have more punch after this tuning.......
b) simply: connect another amp with your headphone jack......
Dear peter 8 , just looked at your picture gallery.
1) if you put aTBA810 compatible there, you will have the same power or have the possibility of very little increase, definitely not worth it.
As in: you can increase power from, say, 4W to 6W ... practically inaudible.
2) if you improve the amp for something more modern , you will have to make a new PCB, use a larger transformer, a different power supply ... and entirely new amp ... which will still have to fit inside your case.
3) from what I see you don't have a preamp there, just a selector switch, a volume control and a passive tone (cut) control .
4) if you want to learn, and use your free time, excellent 🙂 , get any kit you like and build it, search the chipamps section for ideas.
Any doubt on that, we (and others) will be glad to help.
This project is like trying to turn a Topolino
into a Ferrari,
replacing part by part.
In fact, some people tried that and came out with this:
Guess what? .... they spent .... huh ..... a Million dollars on it .... it's still a Topolino inside 🙁
I simply does not work that way, it's better to start from scratch.
Good luck.
1) if you put aTBA810 compatible there, you will have the same power or have the possibility of very little increase, definitely not worth it.
As in: you can increase power from, say, 4W to 6W ... practically inaudible.
2) if you improve the amp for something more modern , you will have to make a new PCB, use a larger transformer, a different power supply ... and entirely new amp ... which will still have to fit inside your case.
3) from what I see you don't have a preamp there, just a selector switch, a volume control and a passive tone (cut) control .
4) if you want to learn, and use your free time, excellent 🙂 , get any kit you like and build it, search the chipamps section for ideas.
Any doubt on that, we (and others) will be glad to help.
This project is like trying to turn a Topolino
An externally hosted image should be here but it was not working when we last tested it.
into a Ferrari,
An externally hosted image should be here but it was not working when we last tested it.
replacing part by part.
In fact, some people tried that and came out with this:
An externally hosted image should be here but it was not working when we last tested it.
Guess what? .... they spent .... huh ..... a Million dollars on it .... it's still a Topolino inside 🙁
I simply does not work that way, it's better to start from scratch.
Good luck.
Hola querido!!!😉
I can't believe my eyes!!!😱...Please confirm me this is real: are you really from Argentina???!!!...tell me that you're really argentine!!!
For me it would be a big surprise for two reasons: first of all, I love Argentina (but unfortunately I've never visit your wonderful country) its culture and the people.I've lived in Barcelona (Spain) during almost ten years and I always cohabited with argentines, my best friends are all argentines!!!Unfortunately last year I got sick, so I had to leave them and my room coming back to Italy.
Second reason: I can speak spanish ( y vos también?!!!🙂) better than english.
For me it would be more easier to write and to understand spanish than english...for me it would be as miracle to get some informations about this project speaking in spanish.As already I said, unfortunately my health conditions are very bad so I'm searching for a little happiness and fun dedicating my time to this crazy project!!!...With this project I'm trying to keep myself active, doing something that I love.
Seria fantastico!!!...puedes confirmarme si hablas castellano?
Thank you so much my friend!😉
Pietro
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