LM1875 under $8.00
Littlediode sell the LM1875 $7.84, that is not too expensive http://www.littlediode.com/components/LM1875_Integrated_Circuit.html
Littlediode sell the LM1875 $7.84, that is not too expensive http://www.littlediode.com/components/LM1875_Integrated_Circuit.html
TDA2030 or LM1875 AMP Basic
Hi,
Since a number of people have been asking for a basic TDA2030 / LM1875 amp design, I have put a schematic together.
I will turn this into a PCB once I have had a bit of feedback to make sure its what you all want.
I have put most of the appropriate input and output protection on this, the only extra part that I would probably add for a comercial design would be a mute relay, but these are quite expensive and if you don't mind a small pop when it turns on its not a problem.
I have also added a very basic 1st order shelf to give a bit of bass boost. If you are using this with a speaker with no baffle step compensation or that is small this will give the sound abit more body. If your speaker eq doesn't need this simply leave these parts out. (C5, R3)
Other things I could do;
1.) Add the bridge rectifier to this to make it a self contained design, but this will make the PCB much bigger?
2.) Stereo design, but obviously this will make it bigger?
3.) Add mute relay?
3.) Do you want a preamp and volume control?
Actually since I used to design HiFi for a living I could do pretty much whatever you want.
If someone is up to it please check my calculations. I did them all by hand and I could easly have messed them up, its quite a while since I did a design and then I normally simulated everything.
Since I fancy a bit of a project but have no need for any more HiFi let me know what you all want and I will have a go at design it. If I am feeling really keen I might even build a prototype.
Don't expect this to happen instantly, I will need to check and recheck everything since it a while since I did this and I am learning a new PCB package as well (Easy PC).
Regards,
Andrew
Hi,
Since a number of people have been asking for a basic TDA2030 / LM1875 amp design, I have put a schematic together.
I will turn this into a PCB once I have had a bit of feedback to make sure its what you all want.
I have put most of the appropriate input and output protection on this, the only extra part that I would probably add for a comercial design would be a mute relay, but these are quite expensive and if you don't mind a small pop when it turns on its not a problem.
I have also added a very basic 1st order shelf to give a bit of bass boost. If you are using this with a speaker with no baffle step compensation or that is small this will give the sound abit more body. If your speaker eq doesn't need this simply leave these parts out. (C5, R3)
Other things I could do;
1.) Add the bridge rectifier to this to make it a self contained design, but this will make the PCB much bigger?
2.) Stereo design, but obviously this will make it bigger?
3.) Add mute relay?
3.) Do you want a preamp and volume control?
Actually since I used to design HiFi for a living I could do pretty much whatever you want.
If someone is up to it please check my calculations. I did them all by hand and I could easly have messed them up, its quite a while since I did a design and then I normally simulated everything.
Since I fancy a bit of a project but have no need for any more HiFi let me know what you all want and I will have a go at design it. If I am feeling really keen I might even build a prototype.
Don't expect this to happen instantly, I will need to check and recheck everything since it a while since I did this and I am learning a new PCB package as well (Easy PC).
Regards,
Andrew
RS components in the uk do a tda2030 pcb for under £1:30
ive just put two of these together with tda2050 chips in, changed values and switched a few components and has room to try different clamp diodes, input caps and zobel.
Welcome to rswww.com and search for tda2030
in my opinion the tda2050 is a much better match up for the lm1875 maybe not quite beating the lm on sound but on price and ease of obtaining and tolerance to faults i think the tda has the edge.
happy playing, steve.
ive just put two of these together with tda2050 chips in, changed values and switched a few components and has room to try different clamp diodes, input caps and zobel.
Welcome to rswww.com and search for tda2030
in my opinion the tda2050 is a much better match up for the lm1875 maybe not quite beating the lm on sound but on price and ease of obtaining and tolerance to faults i think the tda has the edge.
happy playing, steve.
its always worth trying to improve things, the pcb from rs isnt perfect, far from it, its a real compromise board, with layout for single or dual supply a variety of different parts and its larger than needed!
if you ask what every 1 wants then reduce down to the best features, do the layout, post it, then play with it a few times after help and criticism, the board should be better than those you can buy, but only if if has the features people are looking for!
or try it just for yourself! happy designing, steve.
if you ask what every 1 wants then reduce down to the best features, do the layout, post it, then play with it a few times after help and criticism, the board should be better than those you can buy, but only if if has the features people are looking for!
or try it just for yourself! happy designing, steve.
Hi Andrew-
Thanks for your schematic. I am going to use the TDA2030 as a driver for a tube output stage. I got the idea from here-
Electra-Print.com Push-Pull A2 6A3/300B
Jack built some amps that showed up at burning amp that used this driver. This would be a simple project for me to get going on my GM70 PP amp idea for Burning Man.
As I am not a designer, could you help me? Jacks schematic is missing some components that yours (and others I've seen) include. Going by your schematic, missing parts are-
C9 & R12 (is this to stop oscillation?)
D1 & D2 (what is their function?)
C12 (what is it's function?)
C1, C2, C4, C6 (I gather they are just extra filtering?)
All the rest are just variations on the theme to set gain, etc. Your help would be most appreciated.
Thank you- Kent
I'm not so sure LM1875 is so much better then TDA2030. I have LM1875 amp and I had TDA2030 amp (same parts) and TDA2030 amp was winner. The only drawback was somehow big DC offset at the output without feedback and input capacitor. So I replaced TDA2030 with TDA2050 and the DC offset is fine and I like it more then my LM1875 amp.
Hi,
Using this amp to drive a tube output circuit is quite different to my implementation. However see my points below.
As I am not a designer, could you help me? Jacks schematic is missing some components that yours (and others I've seen) include. Going by your schematic, missing parts are-
C9 & R12 (is this to stop oscillation?)
I am not a tube expert so this design may be just fine how it is and it appears that it has been made before. If that is the case I would stick with their sch as it is, however I would query the lack of decoupling they may have just left it off for clarity of the drawing.
Regards,
Andrew
Thank you- Kent[/QUOTE]
Using this amp to drive a tube output circuit is quite different to my implementation. However see my points below.
As I am not a designer, could you help me? Jacks schematic is missing some components that yours (and others I've seen) include. Going by your schematic, missing parts are-
C9 & R12 (is this to stop oscillation?)
Correct - probably not required with the tube output stage but I am not certain on this.
D1 & D2 (what is their function?)They are catch diodes that prevent back emf from the speaker going outside the rails of the amplifer. The speaker is inductive and as an inductive load relaxes it can produce back volatges higher than the source voltage. These diodes prevent the back emf damaging the output stage of the amplifier. (I don't think you need them as the chip is not driving the speaker, however I don't know how the coupling transformer will react)
C12 (what is it's function?)It reduces the DC offset at the output. (You may be able to get away without this as the amplifers gain is quite low)
C1, C2, C4, C6 (I gather they are just extra filtering?)These are power supply decoupling, I am supprised they are not shown in the diagram you have. You will need these or the main PSU caps need to be very very close, I would say you need the 100nF parts where ever the main caps are.
All the rest are just variations on the theme to set gain, etc. Your help would be most appreciated.The gain of this amplifer appears to be 10. The TDA 2030 is only stable at gains of 20 or above so I would be wary of this circuit it is likely to be quite difficult to get stable. However it may be OK as the load is inductive (the transformer) and shouldn't vary much as the chip amp is only driving the tubes not the speaker itself.
I am not a tube expert so this design may be just fine how it is and it appears that it has been made before. If that is the case I would stick with their sch as it is, however I would query the lack of decoupling they may have just left it off for clarity of the drawing.
Regards,
Andrew
Thank you- Kent[/QUOTE]
There's TDA2030 (for higher gain use, not for driver use) and TDA2030A (for lower gain use and for driver use).
I'd have to guess, but it seems like if you mix them up, you'll get either a shouty or a dull sound. An additional guess: If its shouty, increase the gain and/or add stabilizing components. If its dull, reduce the gain and add a preamp. Its an opamp, and this action doesn't differ from the smaller opamps that are made in versions of supporting high gain or low gain.
Fake chips. . . The label may read LM1875, TDA2030, some model of NEC, TDA2040, TDA2050 and anything compatible with 5 pins.
However, if it came from Bangkok, its possibly (probably) none of the above. That's a shame, because the fake is a lovely product in its own right, but requiring reduced voltage and the flyback diodes for proper support. The sound has a slight contour like the TDA2040 and the old NEC. Possibly it is a clone of one of them. Voltage tolerance is lower than LM1875, which is a bad problem when the label is printed LM1875.
The sound quality of the fake chips and their real counterparts (TDA2040, 2050) with "darker voice" than LM1875, is a simple difference in the power circuit and it is timbre is your choice of support circuits, not a fault of any chip.
These can all work equally well and spot-on identical (except for power output), but would do so in optimized support circuits that are different for each model chip.
Plug-n-play is a different thing from pin-compatible.
That's almost all I got on it.
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I trust you.
Therefore, I will have to assume that my samples of TDA2030 is the clone chip, which may have Any printing on it, and performs like the old NEC. That's more noise than LM1875, less voltage capacity, more bass, less durability, a darker voice, vast dynamics, and every bit as clear, a performance not identifiably different from an expensive tube amp, albeit quality control is much different.
If this doesn't describe TDA2030, then mine could be fake.
It depends on the taste. TDA2030 with or without A is clearly not for me. I agree with you with all you described except for dynamics, in which I had the feeling that is poor. Maybe this causes the compressed sound. I like to have the music crisp and accurate, that's why my amp has LM3886. Anyway, for the money you pay for TDA2030A, the sound is good, indeed.
Methinks that 2030A needs significantly different gain setting than LM1875 and maybe 2030A needs a preamp or buffer? I'm not sure. Possibly it makes a bridged driver just fine? Possibly it needs a regulated power supply with low capacitance, signal grade, next to the chip? Probably, a rail-to-rail cap would help the resolution although the difference should be minor.
For the ST products, a heck of a good job with the NFB cap will cure that dynamics problem. Its not easy to do THAT well, while maintaining a level frequency response and the audio as clear as a bell. But, there is no doubt that its doable with component specific design (exact model numbers of parts found the "hard way" via process of elimination) . . . which is not suitable for a production amplifier. If an NFB cap selection is too difficult you can "punt" and use an output cap as its effect is not magnified by the gain. I like it that either can provide additional speaker protection as well as greater dynamics.
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Hi all, I am a new member of forum. Would a newcomer be warmly welcome here? Good day you guys!!!
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