Hi,
Some weeks after having found this forum I have become curious of chip amps. Now I want to build my one ones.
I have also for the last years been thinking of building a pair of TL or horn speakers with fullrange drivers.
Consequently I now want to build those as active speakers with chip amps.
Currently I have a small collection of Quad amplifiers (33,34,303, 405-II, QC-2 and Quad-II:s)
Since I have used my 15W Quad II tube amps with my speakers with only 88dB efficiency I'm quite confident that 10W into a speaker with well above 90dB will be enough for me.
It doesn't matter to me if there is 50W instead of 10W as long as the first 10W is delivered with best possible sound quality.
And If there is not more than 10W thats fine with me - I don't need more.
My local component dealer www.elfa.se offers:
TDA2005, TDA2030, TDA2040, TDA2050, LM3875, LM3886, LM4700 and som others which I don't think will be my choice anyway. There Is offcausse different prices on these, but I think all of them are cheap enough and I will buy the ones from which I can expect the best sound quality.
Now to my question:
In what way will the supply voltage on e.g LM3886 affect the sound quality. Will It benefit to not have more supply voltage than needed or is it better to build an +-48V 68W LM3886 with low gain setting ? ......Or will e.g the TDA2030 perform as good as LM3886 if 10W is all you need?
I have 2pcs of 12-0-12V 20VA torid transformers in my scrap box. Will it be enough with one of these for each channel?
Robert
Some weeks after having found this forum I have become curious of chip amps. Now I want to build my one ones.
I have also for the last years been thinking of building a pair of TL or horn speakers with fullrange drivers.
Consequently I now want to build those as active speakers with chip amps.
Currently I have a small collection of Quad amplifiers (33,34,303, 405-II, QC-2 and Quad-II:s)
Since I have used my 15W Quad II tube amps with my speakers with only 88dB efficiency I'm quite confident that 10W into a speaker with well above 90dB will be enough for me.
It doesn't matter to me if there is 50W instead of 10W as long as the first 10W is delivered with best possible sound quality.
And If there is not more than 10W thats fine with me - I don't need more.
My local component dealer www.elfa.se offers:
TDA2005, TDA2030, TDA2040, TDA2050, LM3875, LM3886, LM4700 and som others which I don't think will be my choice anyway. There Is offcausse different prices on these, but I think all of them are cheap enough and I will buy the ones from which I can expect the best sound quality.
Now to my question:
In what way will the supply voltage on e.g LM3886 affect the sound quality. Will It benefit to not have more supply voltage than needed or is it better to build an +-48V 68W LM3886 with low gain setting ? ......Or will e.g the TDA2030 perform as good as LM3886 if 10W is all you need?
I have 2pcs of 12-0-12V 20VA torid transformers in my scrap box. Will it be enough with one of these for each channel?
Robert
Thank you for the advice Nuuk!
Even if The supplier i planned to buy from doesn't have LM1875 I did find this chip interesting for my purposes.
I asked an TV-repair man if he could order a pair of them for me and it was no problem. It become also very cheap this way.
I have spent some more hours reading this forum and have got some more useful information.
Still I haven't found any posts with any general ideas about the relation between soundquality vs supplyvoltage.
Maby there are hints to read out from the diagrams in the datasheets, but I'm not capable to do it.
However, if no one knows I have to accept this and try to find out for my self.
I have also made my 1st chip amp. It's very low budget with a TDA2003 I bought years ago and with cheap standard components. It sounds but it's offcausse far from good hifi.
see the picture, note the heatsink
Wonder whats the worst of the design? Components too narrow? poor pcb? cheap components?
Even if The supplier i planned to buy from doesn't have LM1875 I did find this chip interesting for my purposes.
I asked an TV-repair man if he could order a pair of them for me and it was no problem. It become also very cheap this way.
I have spent some more hours reading this forum and have got some more useful information.
Still I haven't found any posts with any general ideas about the relation between soundquality vs supplyvoltage.
Maby there are hints to read out from the diagrams in the datasheets, but I'm not capable to do it.
However, if no one knows I have to accept this and try to find out for my self.
I have also made my 1st chip amp. It's very low budget with a TDA2003 I bought years ago and with cheap standard components. It sounds but it's offcausse far from good hifi.
see the picture, note the heatsink
Wonder whats the worst of the design? Components too narrow? poor pcb? cheap components?
Attachments
Robert_66 said:Thank you for the advice Nuuk!
Even if The supplier i planned to buy from doesn't have LM1875 I did find this chip interesting for my purposes.
I asked an TV-repair man if he could order a pair of them for me and it was no problem. It become also very cheap this way.
I have spent some more hours reading this forum and have got some more useful information.
Still I haven't found any posts with any general ideas about the relation between soundquality vs supplyvoltage.
Maby there are hints to read out from the diagrams in the datasheets, but I'm not capable to do it.
However, if no one knows I have to accept this and try to find out for my self.
I have also made my 1st chip amp. It's very low budget with a TDA2003 I bought years ago and with cheap standard components. It sounds but it's offcausse far from good hifi.
see the picture, note the heatsink
Wonder whats the worst of the design? Components too narrow? poor pcb? cheap components?
What is the sch. that you use? I think it may has to do with the IC and the specific sch. and PS. Parts too, but I'd start with the speciffic sch. Use LM1875 and 18-0-18VAC with Pnasonic FC caps and normal resistors. If you can avoid the el. caps at the input and the NFB that's the best IMHO. How sensitive are your speakers? You may need more power than 12V can provide.
Hi Greg GC,
For this quick-and-dirty-allways-learn-something project on the picture I used the "typical configuration" scheme on the TDA2003 datasheet. At this point I regret I did the layout so narrow. It makes it difficult to rebuild and test different modifications.
If I understand it right your opinion is that significant improvements can be made by using an other scheme.
Since my preamp have capacitors on the outputs I think it will be no problem to skip the caps at the input.
I have not yet decided which scheme I will use on my more serious attempt with the LM1875:s, but it will be with some kind of plastic caps in the NFB.
The speakers I'm planning to build will be with 6" Fostex or possibly Lowther fullrange drivers and I think they will be very sensitive - maby 94dB ?!
I'm also afraid that 12V-0-12V AC will be a bit to low. After the rectifier and PS caps It will be approx 16V. This is the minimum supply voltage specified for LM1875.
I think your advice 18V-0-18V AC may be good. It will give approx. 25V DC. This is somewhere between the min and max specified. Most of the ratings specified on the datasheet is valid at 25V. It gives me the feeling that this can't be wrong.
But I will test with the transformers I already got to start with.
It will be easy to make the upgrade later on.
Robert
For this quick-and-dirty-allways-learn-something project on the picture I used the "typical configuration" scheme on the TDA2003 datasheet. At this point I regret I did the layout so narrow. It makes it difficult to rebuild and test different modifications.
If I understand it right your opinion is that significant improvements can be made by using an other scheme.
Since my preamp have capacitors on the outputs I think it will be no problem to skip the caps at the input.
I have not yet decided which scheme I will use on my more serious attempt with the LM1875:s, but it will be with some kind of plastic caps in the NFB.
The speakers I'm planning to build will be with 6" Fostex or possibly Lowther fullrange drivers and I think they will be very sensitive - maby 94dB ?!
I'm also afraid that 12V-0-12V AC will be a bit to low. After the rectifier and PS caps It will be approx 16V. This is the minimum supply voltage specified for LM1875.
I think your advice 18V-0-18V AC may be good. It will give approx. 25V DC. This is somewhere between the min and max specified. Most of the ratings specified on the datasheet is valid at 25V. It gives me the feeling that this can't be wrong.
But I will test with the transformers I already got to start with.
It will be easy to make the upgrade later on.
Robert
Robert,
After looking at the TDA2003 data sheet I can promise you that you'll get much better results from LM1875, 18-0-18VAC. Pick a IGC or NIGC (I build a NIGC no signal caps. LM3875) and enjoy the music. It's worth the effort.
http://www.diyaudio.com/forums/showthread.php?postid=309481#post309481
http://www.diyaudio.com/forums/showthread.php?s=&threadid=23353&perpage=15&pagenumber=1
Greg
After looking at the TDA2003 data sheet I can promise you that you'll get much better results from LM1875, 18-0-18VAC. Pick a IGC or NIGC (I build a NIGC no signal caps. LM3875) and enjoy the music. It's worth the effort.
http://www.diyaudio.com/forums/showthread.php?postid=309481#post309481
http://www.diyaudio.com/forums/showthread.php?s=&threadid=23353&perpage=15&pagenumber=1
Greg
Hi Robert 66;
If the LM1875's not available, you might try the TDA2050; I recently built a TDA2030A and it's sound is significantly better than I thought it would be. I'd still rate my 2A3 as sounding better (given the disparity in costs, I'd be crushed if the reverse was the case!) but I can listen to my TDA2030A all day long without fatigue and better yet I can even enjoy the music through it (not possible on some systems!).
The reason I suggest the 2050 over the 2030A is that the specs look better on it and the blocking diodes are integral to the chip. Personally I'd love to try one but I can't find a supplier on this side of the pond.
The 20VA rating will be a REAL limit to be sure, but it should work - just do NOT hook it up to a 4 ohm load and DO fuse the secondary. Also, as with all new electronics, keep an eye on the temperature of that PS trafo during high power operation to get an idea of how close to it's real capacity you are.
FWIW, I'm running my 2030A into 8 ohms and even runs at max power have not heated the 50VA 25VCT trafo to levels I would regard as dicey. Frankly though, I don't think you can have too much current capacity in a PS, so I'd put in an inexpensive EI core 25VCT rated a bit higher. 50 VA is fine here, but I'd like to go up to something with 2 or 3 times the capacity....
Good luck and all the best!
Morse
PS. Love the heatsink! I wish I would've thought of it!
If the LM1875's not available, you might try the TDA2050; I recently built a TDA2030A and it's sound is significantly better than I thought it would be. I'd still rate my 2A3 as sounding better (given the disparity in costs, I'd be crushed if the reverse was the case!) but I can listen to my TDA2030A all day long without fatigue and better yet I can even enjoy the music through it (not possible on some systems!).
The reason I suggest the 2050 over the 2030A is that the specs look better on it and the blocking diodes are integral to the chip. Personally I'd love to try one but I can't find a supplier on this side of the pond.
The 20VA rating will be a REAL limit to be sure, but it should work - just do NOT hook it up to a 4 ohm load and DO fuse the secondary. Also, as with all new electronics, keep an eye on the temperature of that PS trafo during high power operation to get an idea of how close to it's real capacity you are.
FWIW, I'm running my 2030A into 8 ohms and even runs at max power have not heated the 50VA 25VCT trafo to levels I would regard as dicey. Frankly though, I don't think you can have too much current capacity in a PS, so I'd put in an inexpensive EI core 25VCT rated a bit higher. 50 VA is fine here, but I'd like to go up to something with 2 or 3 times the capacity....
Good luck and all the best!
Morse
PS. Love the heatsink!
I wish I would've thought of it! 
Of the TDA chips, TDA2050 is the best, closely followed by TDA2040. TDA2030 is a little too noisy for my taste, although it depends on the application. I don't think I've ever used a TDA2005.
None of them are quite as good as the LM chips, being more noisy and having worse PSRR. Nevertheless I do still like them because they are very cheap and have only five pins.
None of them are quite as good as the LM chips, being more noisy and having worse PSRR. Nevertheless I do still like them because they are very cheap and have only five pins.
Robert, I try to answer your questions:
1. It is better, generally speaked, to have less supply voltage (within the range of the datasheet, of course)
2. Less gain = more feedback. Too much feedback is not good for the sound.
Regarding chips:
I did not use the LM1875 up to now, but when I look the datasheet, then I think, I prefer a tube amp (the LM1875 has relatively high THD at low output, eg the first watt is not perfect).
My two cents (for high end sound reproduction): try the LM3875 with low voltage, t-net and a gain about 45.
Franz
Edit: I have several gainclones in different configurations driven with different voltages, all with LM3875. The PSU voltage does not affect the sound, definitively!
Nuuk said:
A very good advice.
Franz G said:
Try it, Franz, it sounds good.
Don't discard it just because of the specs.
BTW regarding distortion (and other things
), the LM3886 is the best.Franz G said:
If you use very sensitive and easy to drive speakers you can say that.
But with more "normal" speakers it will lack "juice" sooner.
A question to the moderators: what happened to the old threads?
The chipamp forum has only has 8 pages?!
I was searching for an old thread of mine with a very small amp with 2x12v trafo and didn't find it.
Then I realized that this forum has just 8 pages, and the oldest thread is from October 2004?!
Guess they cleaned up then..
we have to start all over again then..
Franz G: it is good to hear that this is the case, as at least I and probably many more was under the impression that it wat just the opposite.
and Mr Evil: The tda 2005 is'nt worth the printcard it's slderd to.
it really is a horibly sounding thing, at least acording to my ears.
built an amp based around this chip last year at school. not the best design or quality parts, but still: it was beaten massivly by my lm3886 amp.
we have to start all over again then..
Franz G: it is good to hear that this is the case, as at least I and probably many more was under the impression that it wat just the opposite.
and Mr Evil: The tda 2005 is'nt worth the printcard it's slderd to.
it really is a horibly sounding thing, at least acording to my ears.
built an amp based around this chip last year at school. not the best design or quality parts, but still: it was beaten massivly by my lm3886 amp.
tda fan.
the tda 2003 is usualy used with battery power, could be one of the reasons its sound quality wasnt up to much. ive built a few tda2030 amps, and even with just a 25va transfo, running single supply its sound is equal to that of my sherwood 5.1 system, not as loud of course but good sound running into audax ap130g2 speakers.
the tda2050 is great as well from the reports ive seen, and there are some easy build strip board circuits out there. and for approx. 10 dollars for all the bits its gota be worth a try. hope this helps, see you soon steve.. ..
the tda 2003 is usualy used with battery power, could be one of the reasons its sound quality wasnt up to much. ive built a few tda2030 amps, and even with just a 25va transfo, running single supply its sound is equal to that of my sherwood 5.1 system, not as loud of course but good sound running into audax ap130g2 speakers.
the tda2050 is great as well from the reports ive seen, and there are some easy build strip board circuits out there. and for approx. 10 dollars for all the bits its gota be worth a try. hope this helps, see you soon steve.. ..
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