The system with 6 LM3886 chip has been running continuously since last 4 hours with only one 4 amp transformer.
The transformer is slightly warm.
Sound quality is still just brilliant.
And as I said earlier, I don't need the monstrous output.
To be honest, I am more than satisfied with the output level and as well as the deep, detailed, rich, superb sound that is being produced by the system in my 9ft X 12ft ( approx.) listening chamber.
As I read, LM3886 has a under-voltage protection inbuilt with the chip.
Now my questions are:
1. What will be the adverse effect if I continue using the system with this only one 4 amp transformer? How will it affect the system?
I specifically want to know from all of you
2. Will the transformer be burnt in the long run?
3. Will the chips be destroyed after prolonged use?
Kindly reply your experience.
The transformer is slightly warm.
Sound quality is still just brilliant.
And as I said earlier, I don't need the monstrous output.
To be honest, I am more than satisfied with the output level and as well as the deep, detailed, rich, superb sound that is being produced by the system in my 9ft X 12ft ( approx.) listening chamber.
As I read, LM3886 has a under-voltage protection inbuilt with the chip.
Now my questions are:
1. What will be the adverse effect if I continue using the system with this only one 4 amp transformer? How will it affect the system?
I specifically want to know from all of you
2. Will the transformer be burnt in the long run?
3. Will the chips be destroyed after prolonged use?
Kindly reply your experience.
Dear Sir,
This will be the final wiring layout. Please correct my mistakes.
Thank you.
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1, Practically none
2, not unless you are really pushing hard and for continuous period of time
3, not likely.
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.
2, not unless you are really pushing hard and for continuous period of time
3, not likely.
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.
I thank you so much Sangram for your very informative and much needed reply. I will try as per your suggestion and report my tweak back to you and I might need further guidance.
After Sir Andrew approves the layout I will proceed towards another difficult part i.e. the construction of the electronic enclosure / metal cabinet. I need your help there too as you are well aware of the Indian "local market".
So kindly feel free to rectify/ improvise my plan if needed with your experienced suggestion. Thank you.
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Depending on your location (or even independent of it), there are plenty of good audio cabinet makers in India. The problem is that each unit is hand built so if you want products that can match international work, you need to spend a lot, think about 2x of international prices. Which is pretty much the same as importing from a big US or Europe site.
What you get locally is worthless. There is a company called Dinrack that makes 'Desktop' cases for instrumentation that work well and the proprietor is an audio buff so can cut holes to your size etc. Then there is Sound Foundations (one word) which does more audio-specific high-end work. You can see some amplifier cases on their site, of which the Type 1 were built for me. He also built my F5 Turbo cabinets, which are here: http://www.diyaudio.com/forums/pass-labs/207103-f5-turbo-builders-thread-49.html#post3208407 The amp itself is not ready due to a minor snag of circuit boards not being ready yet.
What you get locally is worthless. There is a company called Dinrack that makes 'Desktop' cases for instrumentation that work well and the proprietor is an audio buff so can cut holes to your size etc. Then there is Sound Foundations (one word) which does more audio-specific high-end work. You can see some amplifier cases on their site, of which the Type 1 were built for me. He also built my F5 Turbo cabinets, which are here: http://www.diyaudio.com/forums/pass-labs/207103-f5-turbo-builders-thread-49.html#post3208407 The amp itself is not ready due to a minor snag of circuit boards not being ready yet.
This is DIY active speaker building. With active speakers, adding a new (hopefully better driver or electronic part) piece isn't a whole new build but an adjustment to make it fit.
csom, it will only get better. If you like what you have now, keep going because you will see improvements. Well done on what you have so far.
Very true.
Let's see how I can make it happen. For sure not an easy job for me especially with only local resources.
I am trying to make a 3d model with an approximate ratio of the final thing to be built. And the result is not so optimistic yet.
Here are some snaps.
And best wishes for your build too. Kindly post some photos of your build at your convenience.
Thank you.
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So true again sir.
Earlier my not so "grammatically" built TDA2050 tri-amping easily outperformed many locally available commercial products, even my pricey 5.1 Branded Speakers.
That boosted my spirit to attempt to build "the next level" LM3886 amps after hearing so many positive reviews on innumerable sites. I now "feel" how right each of the reviewers was. So perhaps I bit off more than I could chew by spending a fortune ( as per my financial credential, of course ). But all I can say is that it was really worth spent. "I am loving" the sound.
And of course it is possible because of all of you, the audio gurus. So the credit goes to you all for all your handholding.
Things to do for the time being :
1. Getting an approval of the layout from Sir Andrew
Next,
2. Making the metal cabinet of the amp
And lastly,
3. Redesigning/resizing the earlier DIY Floor Standars. I might use bigger speakers. So I will have to take resort to all of your help once again.
4. And perhaps a little bit of room treatment.
Thank you for you kind encouragement and valuable inputs. I need them more.
post62 looks good.
One final comment about twisted wire pairs.
Some of the pairs are actually triplets.
The three wires from transformer to rectifier, the three wires from rectifier to first stage smoothing, the three wires from first stage smoothing to second stage smoothing, the three wires from second stage smoothing to amplifier.
Note also the three speaker Returns should all be twisted with their respective Flow, NOT commoned.
One final comment about twisted wire pairs.
Some of the pairs are actually triplets.
The three wires from transformer to rectifier, the three wires from rectifier to first stage smoothing, the three wires from first stage smoothing to second stage smoothing, the three wires from second stage smoothing to amplifier.
Note also the three speaker Returns should all be twisted with their respective Flow, NOT commoned.
Oh thank you very much Sir for this much awaited reply.
I was unsure of the Speaker Returns from Mr Mile's circuit. Now its very clear.
Now I can proceed to the cabinet making part.
Just a quick question.
I have seen many reputed companies use RCA sockets for connecting Satellite Speakers in 2.1, 4.1, 5.1 or in 7.1 systems. Sure they can be mounted on the metal cabinet conveniently.
Can I use these sockets to connect the speakers
or
will that be a bad idea considering the high output of LM3886 ?
Kindly reply your experience.
I have seen many reputed companies use RCA sockets for connecting Satellite Speakers in 2.1, 4.1, 5.1 or in 7.1 systems. Sure they can be mounted on the metal cabinet conveniently.
Can I use these sockets to connect the speakers
or
will that be a bad idea considering the high output of LM3886 ?
Kindly reply your experience.
Still in continuous operation, no harm done to the system with underpowered transformer, only a 4 amp for all the 6 LM3886 chips.
It's been running since last two days. Sometimes I play it really loud too.
Meanwhile, the preamp section with microphone input is finished and housed in a separate metal cabinet.
Working very nicely.
Now is the time to work with the cabinet of the power amplifiers and X-over( both in the same metal enclosure ).
Will post updates/photos soon.
Wish me luck.
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Update of my project
Some snaps of my progress of work.
I changed the placement of the components and housed in a an old, discarded cassette recorder cabinet.
Thank you all for your advice and handholding.
Questions:
1. I damaged two tweeters due to my mistake. I connected that to woofer.
Is there a way to protect the tweeters?
2. I want to use two tweeters per channel. Should I connect them in parallel or in series? ( one is of 4 Ohm another is 6 of Ohm )
Thank you again.
Some snaps of my progress of work.
I changed the placement of the components and housed in a an old, discarded cassette recorder cabinet.
Thank you all for your advice and handholding.
Questions:
1. I damaged two tweeters due to my mistake. I connected that to woofer.
Is there a way to protect the tweeters?
2. I want to use two tweeters per channel. Should I connect them in parallel or in series? ( one is of 4 Ohm another is 6 of Ohm )
Thank you again.
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The transformer is fine. As Andrew pointed out, not all of the amps can draw heavy current at the same time, simply because their is only one signal per channel and it cannot be different at the same time point. Therefore, only one amp can get a signal at that time point. (Simplified argument but you get what I mean.)
Use a series capacitor.
Why Do Tweeters Blow When Amplifiers Distort?
Why?
Calculate the impedance in both cases? Is there any benefit or are you likely to cause the chip's protection circuit to activate? (Rhetorical question.)
Thank you sir.
Final Wiring done. Now using two Transformers.
One 4 amp transformer for each channel.
But no perceivable difference in sound.
The sound is still mind blowing as usual.
Thank God, Sir AndrewT was there to kindly correct my grounding plan of the amp.
Can you believe there is no hum or any kind of distortion or clipping even at the maximum volume? !!!
The preamp is behaving very nicely after it was fixed by the advice of our respected Moderator Sir Mooly.
I have no "great" tweeters. And they are low wattage. But with Active X-over they perform very nicely.
I blew two of them as I mistakenly connected them to the woofer output and did a "hum" check by touching the signal input. Silly me.
LM3886 with its monstrous power is ruthless hence.
Could you please recommend the capacitor value? Is it a non-polar cap?
Thank you for the link.
Seems there's no escaping from Respected Rod Elliot who is responsible for my tri-amping addiction and there is no going back to passive X-over again. LOL.
I have two types of tweeter but they sound different. And I like both of their sound. So I want to use both of them in the system.
I will try. Thank you.
Btw, kindly don't forget to post the photo of your system at your convenience.
^^This.
Not only the power output, but the quality of RCA connections is quite terrible. Some of the more expensive plugs and sockets may work, but if you're really tight on cash 4-way Neutrik Speakons will work well for you. They cost around 350 for a set of plug+ socket and two will be enough for a stereo 3-way active setup, if you share one ground wire.
Some Pro amps use 1/4" sockets/plugs, but those are not short-circuit proof meaning you can't plug and unplug them when the amp is running.
Thank you Sir.
The problem is I can find only what is locally available here and most of them are unreliable cheap craps. And as you've rightly guessed,I am tight on cash after making this beast.
I have not shared ground wire rather twisted them as per the advice of Sir Andrew. So six wires per channel.
I found a 6 pin connector ( not too bad ) and using it for the time being.
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What city are you located in? Neutrik is available with any pro audio dealer - not always electronics shops - in almost every city in India.
1/4" plugs and sockets are also widely available.
By shared ground I mean from the amplifier enclosure to the speaker. The connector has 4 poles, you can use one for ground and one each for Low, mid and high positive pole. Each contact is capable of 30A and I would not trust the RCAs to offer a stable connection.
1/4" plugs and sockets are also widely available.
By shared ground I mean from the amplifier enclosure to the speaker. The connector has 4 poles, you can use one for ground and one each for Low, mid and high positive pole. Each contact is capable of 30A and I would not trust the RCAs to offer a stable connection.
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I am located near Calcutta. Do you know any pro audio dealer there in the city? Especially I need to find one for good speakers.
There are between 10 and 15 shops in Chandni Chowk where you can find Speakons, and about 50-60 where you will find 1/4" sockets. Madan Street is filled with Pro audio dealers, you will not have a problem - however pro audio drivers have special needs when used at home, suggest you check on the speaker forums before purchasing.
Back to the question at hand - Naresh Electronics is the most reliable source for Neutrik original products. You need a 4-pole Speakon cable plug and chassis socket per mono channel.
You can also use the imitation products available at some dealers for half the price. Though the quality is not as good as the Neutriks, they are still a hundred times better than cheap RCAs.
Back to the question at hand - Naresh Electronics is the most reliable source for Neutrik original products. You need a 4-pole Speakon cable plug and chassis socket per mono channel.
You can also use the imitation products available at some dealers for half the price. Though the quality is not as good as the Neutriks, they are still a hundred times better than cheap RCAs.
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