Need Help with 3 way LM3886 Gainclone active amplifier

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csom: All drivers need enclosures and crossovers optimised for their specific operating parameters. Though it is possible for a driver to work in a couple of variations in enclosure size and a minor variation may be tolerable, crossovers always have to take into account the exact driver behaviour at the point of crossover.

There are no plug and play designs, no matter who says otherwise. Only if your drivers are of very poor quality will they work equally in all designs, because their performance is so bad that the rest of the product does not make it any worse.

One thing to note about the change in level on your front panel: Note that one, and only one of the level settings is correct. There is no second position of the level controls that offers correct crossover behaviour. I feel you are using them as tone controls, which is not the right way to operate an active crossover, and it is not intended to be used as such.

To understand a bit about how complex it is to design a crossover, and also why an active crossover is not as easy as it is made out to be, read this project by Tarun (tcpip on this forum): The Asawari | dhandanought.org/tcpip

As to on-wall designs, it is not recommended to place a normal dynamic driver in a box on the wall as it severely compromises its radiation pattern and the resulting performance.

If you have a space issue, subwoofers with smaller 'satellite' speakers are the way to go. As Tom says and I have earlier said, post your speaker queries on the speaker forum. You will get far more expert opinions and advice there, because the speaker regulars tend to check that out more often than this one.

Good luck with your project.
 
csom: ...............
There are no plug and play designs, no matter who says otherwise. Only if your drivers are of very poor quality will they work equally in all designs, ........................................
My drivers are not "very bad" sound wise. The only problem is I have no specific data available on them. :(

One thing to note about the change in level on your front panel: Note that one, and only one of the level settings is correct. There is no second position of the level controls that offers correct crossover behaviour. I feel you are using them as tone controls, which is not the right way to operate an active crossover, and it is not intended to be used as such.

True, but since I have no measurement instruments or adequate knowledge of adjustment according to the room acoustics with non standard drivers, this is convenient for me at this moment.


To understand a bit about how complex it is to design a crossover, and also why an active crossover is not as easy as it is made out to be, read this project by Tarun (tcpip on this forum): The Asawari | dhandanought.org/tcpip
.
Thank you very much. I will read.

.....................As Tom says and I have earlier said, post your speaker queries on the speaker forum.
Good luck with your project.

Thank you sir. I will do. Please keep an eye there too.
 
My drivers are not "very bad" sound wise. The only problem is I have no specific data available on them. :(



True, but since I have no measurement instruments or adequate knowledge of adjustment according to the room acoustics with non standard drivers, this is convenient for me at this moment.



Thank you very much. I will read.



Thank you sir. I will do. Please keep an eye there too.

If you have a sound card in your computer, and if you could borrow a measurement microphone, then you could measure a lot of their characteristics, using free software like ARTA; enough to properly design enclosures and crossovers, I think.
 
If you have a sound card in your computer, and if you could borrow a measurement microphone, then you could measure a lot of their characteristics, using free software like ARTA; enough to properly design enclosures and crossovers, I think.

Thank you so much gootee!
I have a sound card and made a custom microphone as a measurement is not accessible to me at this moment.

I have already started a thread in the multi-way forum and fiddling with Arta and Room Eq Wizard and posted some snaps there.
People are very kind and helpful there too like all of you here.
Kindly have a look at there and post your valuable suggestion.
Here is the link:
http://www.diyaudio.com/forums/mult...peaker-plan-lm3886-triamping.html#post3569828
 
dear all readers,
can any one donate me the lm3886 ic thanking you.?because in my small city there is not available this type of ic thanks

Dear Masood,
I can understand your frustration very well.
I had to wait for almost a year to get the chips in my area as I told you earlier.

Meanwhile, why not try a bi-amping or tri-amping with TDA2030 or TDA2050?
You can hardly differentiate between the sound of active bi-amping or tri-amping mode and that of a pair of LM3886 using a passive X-over.

TDA2030 pretty good sounding ( Rs. 15 per piece ) for average Indian music due its kinda compressed sound.

I did the same thing earlier while awaiting the availability of LM3886, and I am still in love with my TDA2050 tri-amped system.

In India, where we have no good drivers and associated good matching crossover available easily, active amplifier is the only solution to obtain pristine sound quality.

Even with LM3886, you might not be able to achieve your "dream sound" if you have crappy speakers and poor quality compressed audio source.

But tri-amping can save you in this situation to a great extent.

You can trust me. I am giving an honest suggestion from my DIY experience.
I opend a TDA2050 thread here long ago and got help from many kind members.

And for Active X-over, there are plenty of tested circuits both in our forum and on the internet. Sir Mile, APEXAUDIO, has posted some. Rod Elliot has some good quality Active X-over circuits too. ( In fact I made my first two way active X-over following his site and was amazed at the unprecedented impressive sound. )

At present I have 3 systems.

1) One with tri-amped TDA2050, ( with 6 TDA chips, Rs. 30 to 45 per piece)
2) another with tri-amped LM3886 ( with 6 LM3886 chips )
3) and the last one is just a normal stereo with a passive two way system ( With 2 LM3886 chips, I just made this to compare the sound with my active Tri-amped system)

I tested 3 systems simultaneously using the same input source, using a 5 band equalizer for spectrum enhancement.

The sound of system 1 and system 2 is really great and one can't really tell the difference at low volume and they are a clear winner over system 3 or way better than system 3 which has also been made using 2 LM3886 chips.

If you find no LM3886 for the time being, you can easily get 6 TDA2050 chips at the cost of an LM3886 easily.

Or if anyone can donate you some LM3886 chips, that will be a different story.

Anyway, just added my two cents to heal your utterly frustrated desperation.

Good luck. Hope someone will donate you if they can.
 
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dear csom,
thank for your advice,i have two pair of mosfet 2sk1058 and 2sj 162 how will the sound of these mosfet do u have any experience .thank u sir

Dear Masood,
A good sound depends on several factors, as I learnt from reading innumerable posts by the audio gurus here and from my personal DIY experience and I am still learning each day here at Diyaudio forum with the kind help of all.

1. Quality of components.
2. PCB layout design
3. Adequate filtration of the power source
4. Proper grounding ( very important )
5. The quality of audio source and preamp
6. Quality of speakers and cross over
7. Your listening environment etc.

Any compromise is bound to affect the proper reproduction of the desired sound.

I assembled/ built/tested at least 6 discrete amplifiers. You know good quality components are beyond the scope of average Indian hobbyists. And more, the cheap commercial "high end" discrete MOSFET Amp kits available locally, use low quality components, badly designed PCB and inadequate filter capacitors. Result ? Hum, unwanted noise. They let you feel that they are switched on. :) But they are loud ( with distortion figure too ). I felt the same with classic 2N3055 kits too.

Let me share with you a fact. Last year I purchased a so called "high end 1600 watt MOSFET kit" with much optimism. When everything done, I felt a low hum. I informed the vendor and he simply said "oh this is normal with such a high power kit". What the ....! I spent my money to buy a High End Humming Amp!!!!!!??? I was utterly frustrated. I tried increasing the filter caps and somehow I was able to tame down the hum to a certain tolerable level. But there was a wonky crossover distortion. And in Indian local situation, there is a "no return" policy once the "...." is sold.

Meanwhile, I was reading about TDA2030 chip on the net. I studied the data sheet and found a PCB design there. It was so simple. I used a marker pen and drew the PCB layout following the datasheet and etched it. And when I casually finished the amp, .....oh my god! The sound quality was far superior than my purchased "High end commercial ...." kit. I felt that my speakers were in need of that chip as their perfect companion.
Then I went one step ahead. And made a two way active amplifier following Sir Rod Elliot's two way cross over. Result? Unprecedentedly astonishing sound quality. My cousin brother who works in a studio with high end devices, was simply addicted to the detailed and rich sound and listened for three hours at a stretch until dad reminded us that it was almost dawn and "we must take some rest"! And the sound was coming out of an amp that cost me less than 4 packs of cigarette! And there was no crossover distortion!

I just had to discard my "high end discrete .... " and "upgrade" to TDA2050 as I needed a little more power. And that experience made me a lifelong fan of Chip amps for good.

My point of sharing this personal experience with you is that listening environment is also important. Do you really need monstrous power at home? Why not learn to polish your PCB making skill, designing PCB layout of both the amp and cross over, and develop a small low cost board with TDA2030 ( which should cost you less than a pack of cigarette ) meanwhile? Even a set of TDA2030 in stereo tri-amping mode can give you a pretty loud yet very rich sound!

LM3886 will surely be available in your locality very soon, if not today, tomorrow for sure.

My humble suggestion is if you can afford, go for an active amplifier system like I made and it will definitely and clearly outperform any of the locally available commercial craps. You will be pleasantly surprised, I can bet.

I followed Sir Rod Elliot's advice about using active X-over system, given on his website and I now feel how right he is!
For proper ground connection, kindly follow Sir AndrewT's posts, for a dead quiet system.

Hope this helps.
 
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.......
Indian music, for the most part is recorded and mixed by rank amateurs with absolutely no taste and no sense of balance. It has too much treble and the bass cuts abruptly at 60Hz, which means a properly balanced system sounds quite bad when playing it back. ......


.........
To adjust signal levels, download a white noise signal and adjust till the mid, high and low are playing at approximately the same level, it will be closer than your ear. Use pink noise to test whether you got the result correctly. White noise has equal power in each octave range, and pink tapers it at 6dB/octave, more representative of normal music (not Indian music, that's more like white noise with bass boost).

Keep levels very low when playing white noise.



Dear sir, your these two posts are a must read for any diy-audio enthusiast with Indian origin.
These clearly states the fact. Excellent comparison.
I guess it's an observation of a life time.

Having built an audio spectrum analyser and having learnt how to obtain the TSP with LIMP and how to use those to build a suitable/optimized enclosure and test their performance with TrueRTA, your words are so very clear to me now.

That white noise reference was really helpful to tune my system to make Indian music sound better. What you mentioned is just the 100% truth. And I'm reporting this back to you after listening to several uncompressed tracks with many genres.

It's a rare privilege to learn this fact from you as I sincerely think.

And more, now I really feel what an experienced man you are, your knowledge and your passion about audio!

So, hats off to you, sir.
And thank you so much!
 
Hi Som, that first quote could easily apply to many UK recordings from the past, all high and mid range with almost no bass. Some of my old vinyl records sound so bad that I can't bring myself listen to them at all now. I did toy with the idea of tone controls but I don't see why I should compromise my good sounding material by playing it through a system which has been deliberately modified to make bad recordings sound 'nicer'.

I'm now thinking about setting up my old CD recorder with an eq device of some sort so that I can record some old vinyl records (which I cant find a re-master of) onto CD's. It might be worth giving it a go but i'll need a cheap tone control board between my turntable and my CD recorder. Another project which has a low priority for me :D

Slainte

Davy
 
Hi Som, that first quote could easily apply to many UK recordings from the past, all high and mid range with almost no bass. Some of my old vinyl records sound so bad that I can't bring myself listen to them at all now. I did toy with the idea of tone controls but I don't see why I should compromise my good sounding material by playing it through a system which has been deliberately modified to make bad recordings sound 'nicer'.

I'm now thinking about setting up my old CD recorder with an eq device of some sort so that I can record some old vinyl records (which I cant find a re-master of) onto CD's. It might be worth giving it a go but i'll need a cheap tone control board between my turntable and my CD recorder. Another project which has a low priority for me :D

Slainte

Davy

Right Davy. :)
Perhaps earlier, the recording technology was a factor then. But as pointed out by Sangram, the wise man, most of the not-so-old or average Indian recordings are simply not good or I should say pure craps.
Though HMV, EMI etc. have done some excellent jobs, many not so famous mushrooms simply ruined many awesome tracks with the reasons better known to them. :(

But the main factor for sticking to them is nostalgia ( and mid-life crisis.....perhaps, :D).

EQing is a must have thing to do. In fact with pc it is easier to make EQ presets. Any high end sound card with selectable presets will serve that purpose on the fly nicely as I believe.

I am too lazy to add my "special touch" to the oldies with a sound editor. Lots of work! :D So I follow the "On the fly" EQ preset way. :)

And good luck with your forth coming project. :)

Thanks for your post. :)
 
Cheers Som. I'm afraid I don't have much patience for messing around with PC's. I do use one as a digital source for playing FLAC music files through a USB DAC but if it's not plug and play I quickly loose interest.

I used to dislike the things immensely, that dates back to the mid 1980's and too many hours of my life wasted trying to work with gw basic. :eek::headbash:
 
Dear som sir,
I lived in Andhra pradesh, I don't know where I can get the pcb copper clads. Can you give some online dealer website address where you used to buy those pcb clads. their price for minimum quantity and sizes. please also share the easy way method to get nice looking pcbs. thank you in advance.


I purchase it from a local dealer. I have no online purchase facility available yet.
Always buy a fibre-glass based copper board. These are way better and more durable than normal/cheap ones.

The price varies from time to time.
Last I bought a 3' X2' fibre-glass board @ Rs. 900+ from a man who manufactures PCB locally. But that was possible because of a personal source else he doesn't sell the board.

Earlier I used to buy the boards from some reputed shops which sell all kind of industrial components. But naturally their rates are higher.

1. You can ask the board in the shops in your locality where they sell "industrial components". I am sure there are many shops in Hyderabad or in your specific locality.

A little bit of googling fetched me some online dealers:

a) RAW 100 X 160MM S/S Fotomechanix | Single sided copper-clad board,160x100mm | 435-484 | Welcome to RS Online

b) Buy Copper Pcb Clad Circuit Board Single Side 30x30 Cm Online | Best Prices in India: Rediff Shopping

c) FR4 Copper Clad Circuit Board DOUBLE 2 Side 30x30CM PCB | eBay

and so on.

But I guess you can get cheaper rates in your local shops.

2. And regarding PCB making: Just follow the method written below and you will get a professional result at home like I do in my Bedroom-lab. :)

a) Print the circuit with a laser printer using a good quality inkjet photo-paper. This is the most important part. This will give you a great result, I can assure you.

b) Clean the Copper clad board of the same size (after cutting it) with water and Scotch-Brite that is used to clean the cooking utensils. Wipe it off with a soft and very clean cloth and let it dry for a minute or two. Never ever touch the cleaned copper surface with your hand once its cleaned.

c) Get a small sized plywood plank where you can place the pcb firmly. The surface of the plank is rough, so you won't need any addition fixing material to prevent the PCB getting slipped while you use toner transfer method. Also the pre-heating of the board is NOT required.

d) Set the knob of the electric Iron to the maximum temperature position and wait till it reaches the maximum temperature. Now press the tip of the iron to slowly but firmly over the photopaper and start pressing the paper against the board.

When each and every impression is clearly visible on the overleaf ( the white side of the photo paper where the circuit has not been printed) you can stop ironing. For a very tiny board like APEX GAINCLONE PCB, it might take some 4 to 5 mins.

e) Now slowly peel off the paper when the board is slightly hot. If it's a clean and excellent transfer, the photo-paper should come out easily.
If not, put the board into some cold water and wait for 30 minutes. Then use your thumb to rub and easily remove the excess paper.

f) Etch the board using your preferred method. I use Ferric Chloride solution (1:3) because I can re-use that.

g) When etching is done, remove the toner with Thinner solution and you will get the shiny copper tracks.

h) You can apply a solution to protect or weatherproof the copper tracks.
For this I use a little amount of resin diluted in thinner. It helps to solder the components too.

i) I print the component layer too using the method described earlier (except the etching part).

j) For the drilling part, I now use a high speed micro drill purchased locally.

Below is a link of an old video of mine that I uploaded earlier on this topic as my personal learning experience. But now, I neither use that transparent paper nor I pre-heat the board.
I use only photo paper now and that saved me from many hassles.
You can get some help for the etching part and the size of the container, removing toners etc. in that video.
I forgot to wear protective gloves etc. but you should definitely take care about your hands and eyes because it's a risky process. Follow the method with caution at your own risk.
Here is the link of my old video: DIY PCB: Home made Double Sided PCB-Home brewed dual layer PCB - YouTube

And here are some photos of the result that I get using photo-paper.

Good luck with your project.
 

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Thank you Som sir for your kind information. I ll try your process when i get those pcb clads. Thank you again.

You are welcome.

I am tempted to spontaneously advise something, considering the fact that you are a DIYAUDIO enthusiast from Indian Origin and having limited access to truly world class Speakers/drivers and limited resource ( like myself).

First of all, learn to scientifically build your speaker enclosures as per your listening environment.

If you have a pair properly built and well-tuned enclosures, almost any amplifier will sound great especially if you are a fan of music in compressed format. Even the locally available "2N3055+ quad opamp" based high quality discrete kits will sound great.

And take resort to bi-amping or tri-amping if you can, with 2 way or 3 way active cross-over network ( Active amplifiers) .

I had built a 2 way active X-over too following Rod Elliot's design earlier. And the sound of the system was something unprecedentedly charming for me.

Then I upgraded to a 3 way active crossover system which, in the opinion of all of my RL friends( one has a serious professional multimedia studio experience), is "superb", "amazing", "This is far better than my costly ..... or ....... brand home theatre" etc. And they visit me many times just to listen to my DIY audio system. :)

Well this is the magic of Active amplifier system. It's difficult to express the pristine sound quality unless you have not heard one yourself.

I just sincerely followed the advice of Sir Rod Elliot, posted on his website.

Trust me, you won't regret the decision.

Many great resources are available here and on the web too.

Last but not the least, use uncompressed format ( flac, wav, or audio CD etc.) for your audio system to realise its true potential.
Mp3 or other highly compressed format simply kills many additional finer details of the track. There is hardly any scope for improvement or reinforcement however much you may try with DSP or multi-band Equalisation once the music is compressed unless the recording is very old.

So, good luck with your project.

God bless.
 
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