Hi all,
I made the LM3886 in a PCB as per Apex's design with so much optimism but alas! It's not working for me.I am lost where I made the mistake.
I powered it up with a 15-0-15 VAC 2 amp transformer . Voltages are okay. But no sound, no hum. Total silent.
Is the IC faulty?
Need your kind suggestion/guidance to make it work.
Thank you.
Zener 16V is for turn on delay but your PSU voltage with 2x15vac is too low, just use 5V6 zener instead 16V and that will unmute LM3886.
First a big "thank you" to Apex and Port..
Problem solved.
Changing the zener to 5.6volt did the magic.
Also I love the slow start up. No start-up or power off thumping of the speakers. I tested the amp in series with a 60watt lamp and to my utter surprise, the lamp didn't glow even at a loud volume. But with TDA2050 it glows.
1. Does this mean that LM3886 is extremely power efficient?
I played continuously, for some 1+ hour, various genres of music - parts of some of my favourite ones that I listen often ( right from 1956 to 2013) connecting directly to the audio source without any equalizer or preamp. But still, all played extremely well, I must say. I tested it with a very cheap passive 2way speaker system with only one channel. Even then it sounded brilliant. This chip has enough punch to drive the woofer. Clarity is great. It sounded better in that speakers than TDA2050 did.
Now I want to make six sets of this LM3886 and connect those to an Active 3 way Linkwitz–Rileycrossover system. My arrangement will be like the following:
Stereo Audio Source -> Rod Elliot's Project 88 preamp -> 2 X ML3 tone controls -> Active 3 way crossover X 2 -> 6 sets of LM3886 power amp
2. Is this arrangement okay or an overkill? Kindly guide me.
My listening environment or room size is small ( some 10X12 ft) . And I prefer to listen at low volume. I want to use a single transformer for 6 chips. 2 chips will drive the 8 Ohm woofers, 2 will be for 4 Ohms midrange and 2 for 4 Ohms tweeters.
3. Could you please advise on the minimum transformer rating in ampere for the 6 LM3886 chips ?
4. Earlier I requested Apex to kindly provide us a stereo 3 band Equalizer with dual potentiometers in a single board. That compact design will save us the space in the cabinet. Please consider this request.
Thanks a lot, Apex and all, for the help.
.Problem solved.
Changing the zener to 5.6volt did the magic.
Also I love the slow start up. No start-up or power off thumping of the speakers. I tested the amp in series with a 60watt lamp and to my utter surprise, the lamp didn't glow even at a loud volume. But with TDA2050 it glows.
1. Does this mean that LM3886 is extremely power efficient?
I played continuously, for some 1+ hour, various genres of music - parts of some of my favourite ones that I listen often ( right from 1956 to 2013) connecting directly to the audio source without any equalizer or preamp. But still, all played extremely well, I must say. I tested it with a very cheap passive 2way speaker system with only one channel. Even then it sounded brilliant. This chip has enough punch to drive the woofer. Clarity is great. It sounded better in that speakers than TDA2050 did.
Now I want to make six sets of this LM3886 and connect those to an Active 3 way Linkwitz–Rileycrossover system. My arrangement will be like the following:
Stereo Audio Source -> Rod Elliot's Project 88 preamp -> 2 X ML3 tone controls -> Active 3 way crossover X 2 -> 6 sets of LM3886 power amp
2. Is this arrangement okay or an overkill? Kindly guide me.
My listening environment or room size is small ( some 10X12 ft) . And I prefer to listen at low volume. I want to use a single transformer for 6 chips. 2 chips will drive the 8 Ohm woofers, 2 will be for 4 Ohms midrange and 2 for 4 Ohms tweeters.
3. Could you please advise on the minimum transformer rating in ampere for the 6 LM3886 chips ?
4. Earlier I requested Apex to kindly provide us a stereo 3 band Equalizer with dual potentiometers in a single board. That compact design will save us the space in the cabinet. Please consider this request.
Thanks a lot, Apex and all, for the help.
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At the least, I would use two transformers, for two power supplies, and make two tri-amps with three LM3886 each, so that you would have a completely separate "stand-alone" tri-amp for each speaker in a stereo pair of speakers. You might decide that you want to locate one tri-amplifier at each channel's speaker cabinet. And I think that the performance would probably be better, with them separate.
Additionally, you might also want to consider further dividing the power supplies. One option might be to have one separate amp and one separate power supply for the bass, for each speaker, and another power supply and a bi-amp for each speaker's mid and high.
A second option, which would probably give the highest-quality sound, would be to have a separate power supply and amp for every bass, mid, and treble amp, i.e. six separate power supplies and six separate amps. They might not all be identical, since lower frequencies would probably need more reservoir capacitance for the power supply and more decoupling capacitance at the LM3886 power pins.
Or maybe, for option two, you would combine each power supply with an amp, on one board, for six boards total. Similarly, for option one, you might consider putting each PSU and Amp combo on one board, for four boards total.
Additionally, you might also want to consider further dividing the power supplies. One option might be to have one separate amp and one separate power supply for the bass, for each speaker, and another power supply and a bi-amp for each speaker's mid and high.
A second option, which would probably give the highest-quality sound, would be to have a separate power supply and amp for every bass, mid, and treble amp, i.e. six separate power supplies and six separate amps. They might not all be identical, since lower frequencies would probably need more reservoir capacitance for the power supply and more decoupling capacitance at the LM3886 power pins.
Or maybe, for option two, you would combine each power supply with an amp, on one board, for six boards total. Similarly, for option one, you might consider putting each PSU and Amp combo on one board, for four boards total.
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Thank you so much Gootee for your kind reply.
Here I'm posting my current setup of TDA2050 along with 3 way active cross over ( kindly see the attachment ) that has been running really great with my entire satisfaction since last some 6 months without a single problem. The system has a great, crystal clear, dynamic sound stage and absolutely no unwanted perceivable noise, hum etc.
My aim is to replace the TDA2050 ones with Apex's great LM3886 boards with as few transformers as possible.
Using two transformers and putting 3 amps together in the speaker enclosure box are indeed great suggestions for my specific case. But I am worried about the length of long 6 signal cables and an additional power cord. But I will try that and report the result back to you here.
For your second suggestion, could you kindly post a diagram or sketch of your suggested arrangement to make it more clear for me? I am bit lost with the number of transformers there.
And kindly suggest the rating of the transformers too. As I stated earlier, I don't need the full thundering sound just the great quality at low volume with all the details.
Thank you once again.
Here I'm posting my current setup of TDA2050 along with 3 way active cross over ( kindly see the attachment ) that has been running really great with my entire satisfaction since last some 6 months without a single problem. The system has a great, crystal clear, dynamic sound stage and absolutely no unwanted perceivable noise, hum etc.
My aim is to replace the TDA2050 ones with Apex's great LM3886 boards with as few transformers as possible.
Using two transformers and putting 3 amps together in the speaker enclosure box are indeed great suggestions for my specific case. But I am worried about the length of long 6 signal cables and an additional power cord. But I will try that and report the result back to you here.
For your second suggestion, could you kindly post a diagram or sketch of your suggested arrangement to make it more clear for me? I am bit lost with the number of transformers there.
And kindly suggest the rating of the transformers too. As I stated earlier, I don't need the full thundering sound just the great quality at low volume with all the details.
Thank you once again.
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Do not worry about longer signal interconnects.
Short speaker cables give more advantages than you lose with long interconnects.
But,
ensure the Source can drive the interconnects. This means the Source must be able to drive some capacitance in parallel to the input impedances of the active filters. i.e low output impedance and adequate current capability.
Short speaker cables give more advantages than you lose with long interconnects.
But,
ensure the Source can drive the interconnects. This means the Source must be able to drive some capacitance in parallel to the input impedances of the active filters. i.e low output impedance and adequate current capability.
Thank you Sir for taking time to post your valuable words.
I am using Rod Elliott's Project 88 Preamp in the intermediate stage between the equalizer and Xover at this moment.
I will follow your and gootee's kind suggestion
I am in the process of making ML3 and LM3886 PCBs. I will post the photos shortly.
Thank you again.
I am using Rod Elliott's Project 88 Preamp in the intermediate stage between the equalizer and Xover at this moment.
I will follow your and gootee's kind suggestion
I am in the process of making ML3 and LM3886 PCBs. I will post the photos shortly.
Thank you again.
Hi Masood,
I have been trying to purchase LM3886 chips since last 1 year or so. I bought it in Calcutta but not many vendors keep stock of this IC. Recently, from some unconfirmed source, I heard that some shops are selling this Chip @150 INR while I bought this @425 INR per piece ( tf version ) earlier as I can remember. And the shopkeeper brought that from another shop and obviously he didn't disclose me the source. But I was drooling then hearing "it is available but we need some time to bring it" and I didn't have the time to check out the price in other shops.
This is a real problem in India.
Good branded speakers or variety of parts cannot easily be obtained in India in all the locations. Also it costs a lot of money due to several factors. Many a time we have no other option but to use cheap, low quality and unreliable Chinese components from the local markets. But if you can manage to get a pair and build the amp using Apex's Design, I can assure you that you will be extremely happy with the sound this chip produces.
I will post the photo of my build very soon.
All the very best.
Hi Masood,
You are welcome.
Here I am tempted to express my purely personal experience with High-wattage Discrete Mosfet Amp from a hobbyist's standpoint. And there is a good chance that many won't agree with me.
I bought/assembled/made and tested several Discrete Kits available locally in India. Initially I has happy with their performance. But after the honeymoon with them was over, I discovered a slight hum developed in some kits due to improper designs, lack of good components hampering the performance, bad quality transformers, low quality variable resistors leading to missing dynamic sound stage etc. Their output was high and they were reliable but still I was not very happy with them sound wise after some 6 months or so. And more we can't easily buy good branded speakers without spending a fortune. You know the Indian condition very well.
Our respected experienced member Andrew T has mentioned and warned us many times about improper grounding. And I found this problem even in some commercially available kit too. Also if I can remember rightly, our respected Mr. Miles who knows the real thing about audio, once wrote that even 35 watt is good for home listening. Please correct me if I'm wrong. He has many discrete circuits too. May be you can try one of them.
In a nutshell , we need quality as well as stability. I finished a recent project with TDA2050. I can safely say that I am extremely happy with the crystal clear, detailed sound stage. And this IC is very cheap and reliable too as I have seen.
My suggestion is if you can't obtain LM3886 immediately just wait. Meanwhile you can give TDA2050 a try with bi-amping or tri-amping. That won't hurt your pocket much. That's a pretty capable and powerful chip with excellent price performance ratio.
You can make a PCB very easily with a permanent marker pen following the datasheet.
Btw, I trashed all my Hi-wattage Mosfet kits after listening to the awesomeness of LM3886 amp using Apex's truly great design. My plan is to do tri-amping with them. Right at this moment while writing this reply to you, I am testing one LM3886 amp I made some days ago, with only a ONE AMPERE 18-0-18 VAC Transformer in series with a 60watt Lamp. Even then the sound quality is simply mind blowing.
I just shared my personal opinion. You are the one to decide as per your need.
All the very best.
You are welcome.
Here I am tempted to express my purely personal experience with High-wattage Discrete Mosfet Amp from a hobbyist's standpoint. And there is a good chance that many won't agree with me.
I bought/assembled/made and tested several Discrete Kits available locally in India. Initially I has happy with their performance. But after the honeymoon with them was over, I discovered a slight hum developed in some kits due to improper designs, lack of good components hampering the performance, bad quality transformers, low quality variable resistors leading to missing dynamic sound stage etc. Their output was high and they were reliable but still I was not very happy with them sound wise after some 6 months or so. And more we can't easily buy good branded speakers without spending a fortune. You know the Indian condition very well.
Our respected experienced member Andrew T has mentioned and warned us many times about improper grounding. And I found this problem even in some commercially available kit too. Also if I can remember rightly, our respected Mr. Miles who knows the real thing about audio, once wrote that even 35 watt is good for home listening. Please correct me if I'm wrong. He has many discrete circuits too. May be you can try one of them.
In a nutshell , we need quality as well as stability. I finished a recent project with TDA2050. I can safely say that I am extremely happy with the crystal clear, detailed sound stage. And this IC is very cheap and reliable too as I have seen.
My suggestion is if you can't obtain LM3886 immediately just wait. Meanwhile you can give TDA2050 a try with bi-amping or tri-amping. That won't hurt your pocket much. That's a pretty capable and powerful chip with excellent price performance ratio.
You can make a PCB very easily with a permanent marker pen following the datasheet.
Btw, I trashed all my Hi-wattage Mosfet kits after listening to the awesomeness of LM3886 amp using Apex's truly great design.
My plan is to do tri-amping with them. Right at this moment while writing this reply to you, I am testing one LM3886 amp I made some days ago, with only a ONE AMPERE 18-0-18 VAC Transformer in series with a 60watt Lamp. Even then the sound quality is simply mind blowing.I just shared my personal opinion. You are the one to decide as per your need.
All the very best.
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Masood
Csom's advice in his wonderfully written post should be heeded, I believe. The chips certainly can sound incredible. Maybe you can tell us the efficiency of the speakers you would like to drive. 500W for stereo is insane in most cases. Not necessary. Did you know that you get a 3dB boost in volume for every time you double wattage? So:
86dB speakers go like this....
86dB, 1W
89dB, 2W
92dB, 4W
95dB, 8W
98dB, 16W
101dB, 32W
104dB, 64W (personally I think this is more than anyone needs as most speakers are more than 86dB efficient. Mine are 96dB with 1W! and thats not as efficient as a lot of them)
107dB, 128W
110dB, 256W... getting silly isnt it?
113dB, 512W... wow, do we really need to waste another 512W to get 3dB louder?!!? We could have just selected efficient speakers from the start.
Lets try that. My 96dB speakers..
96-1
99-2
102-4
105-8
108-16
111-32
114-64 and now its louder than the 512W amp with the 86dB efficient speakers...
So, with efficient speakers and a few TDA chips you could easily have earsplitting volume.
Uriah
Csom's advice in his wonderfully written post should be heeded, I believe. The chips certainly can sound incredible. Maybe you can tell us the efficiency of the speakers you would like to drive. 500W for stereo is insane in most cases. Not necessary. Did you know that you get a 3dB boost in volume for every time you double wattage? So:
86dB speakers go like this....
86dB, 1W
89dB, 2W
92dB, 4W
95dB, 8W
98dB, 16W
101dB, 32W
104dB, 64W (personally I think this is more than anyone needs as most speakers are more than 86dB efficient. Mine are 96dB with 1W! and thats not as efficient as a lot of them)
107dB, 128W
110dB, 256W... getting silly isnt it?
113dB, 512W... wow, do we really need to waste another 512W to get 3dB louder?!!? We could have just selected efficient speakers from the start.
Lets try that. My 96dB speakers..
96-1
99-2
102-4
105-8
108-16
111-32
114-64 and now its louder than the 512W amp with the 86dB efficient speakers...
So, with efficient speakers and a few TDA chips you could easily have earsplitting volume.
Uriah
Well I'm finally getting around to building this amp, I just need to ask that would it be okay to run this with a 2x24V 200VA trafo for stereo with a 2A fuse before it on the hot line to run my 8ohm 50W speakers, and would I need to change any components on this PCB. Thanks
2x24V trafo will be ok without changes
LM3886
i have some LM3886 Left
here is the Link
http://www.ebay.in/itm/230994187315?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649
i have some LM3886 Left
here is the Link
http://www.ebay.in/itm/230994187315?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649
Dear apex,
Your LM3886 design working truly great with 15-0-15 VAC since I changed the zener to 5.6v as per your suggestion
.
Now I've just bought a 4 amp 23-0-23 VAC transformer to power it up.
Can I leave the 5.6V zener there in the board as it is
or
should I change it back again to the recommended 16v Zener?
Perhaps the culprit is 5.6 v zener instead of the recommended 16v with the increased voltage? or I'm not sure.
I just noticed one thing. I switched on the celling fan of the room and now its completely cool, not even warm.
The temperature here is like 33 C at this moment.