It doesn't mean the system didn't run out of it, just because you didn't hear it.
Also there are ppl saying for a single 3886 they could hear difference between 150 and 200VA trafo.
Also trafos should not be used on max. Minimum 1.5x bigger. But never less then the required. If the price is a problem than I understand, but undersized trafo is not a good sign.
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it is the same.
A single amplifier with a maximum output of 50W can use a transformer rated from 50VA to 100VA.
A pair of 50W amplifiers can use a transformer rated from 100VA to 200VA.
A 3channel amplifier each of 50W can use a transformer rated from 150VA to 300VA.
All that assumes that each amplifier can deliver maximum power for a short period say 1second for a music/audio crescendo.
But in reality not all the amplifiers will draw maximum power at the same time.
Further with an active system feeding bass and mid and treble drivers, it is virtually impossible for all three amplifiers to draw the same maximum power at the same time. It just does not happen in music/audio signals. It would be quite difficult to engineer a test signal that could achieve that. It would need 3 sinewave tones sent at the same time to the active crossover and these to be split correctly to feed the same level to all three amplifiers.
Now to take advantage of the non simultaneous max power to all three active drivers it is not unreasonable to reduce the maximum continuous transformer rating. I would expect as low as half VA rating to work quite well for a 3 band active system.
Finally, a total of 90W or 150W from three chipamps does NOT need more voltage from the transformer compared to 50W from a single chipamp.
The current requirement goes up, not the voltage.
Increased VA rating at the same voltage is that extra current capability.
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Thank you Sir.
Then I will add another pair of 4700 uFd caps to the PSU consisting of a single Transformer.
My heartfelt thanks to you really, Gootee !
Wonderful post! Just what I needed. Amazing!
Your this post will be an excellent reference to many newcomers like me, I am quite sure!
Now I am going to use 4 X 4700uFd caps per rail.
So it will be a total of 8 caps in the PSU.
Does Rload mean Speaker Impedance?
I guess it's 8 Ohm in your spread sheet.
The Midrange Speaker I am using is a 4 Ohm one.
Same for the tweeters too.
So I guess I can safely use the midrange speakers and the tweeters when I will add the additional caps.
Kindly correct me If I am wrong.
Thank you again.
Dear Sir,
Another question.
From which point should I make the connection to Metal Chassis Earth?
The Incoming PE (green/yellow) goes directly and permanently to Chassis. This is the Safety Earth.
You also need a Main Audio Ground to Chassis connection just in case some mains voltage gets on to your audio circuits. All exposed conductive parts must be connected to PE.
This can be a direct connection from any part of the Power Ground to the any part of the Chassis. But this route MUST be capable of passing Fault Current until the Mains Fuse has ruptured and the arc extinguished. This route can pass kA of current. A resistor cannot pass this current !!!!!!!!
You also need a Main Audio Ground to Chassis connection just in case some mains voltage gets on to your audio circuits. All exposed conductive parts must be connected to PE.
This can be a direct connection from any part of the Power Ground to the any part of the Chassis. But this route MUST be capable of passing Fault Current until the Mains Fuse has ruptured and the arc extinguished. This route can pass kA of current. A resistor cannot pass this current !!!!!!!!
But the voltage is not indifferent.
He will use a 2x26V trafo.
Lets count.
2x26V 50VA trafo can only do 1A. So he can make 8W max. at 8 ohm
VA is not everything.
Even a 100VA will only have 2A, so 32W at 8 ohm. Even worse at 4 ohm.
Ppl use 100VA trafos with 2x18V, not 26. nearly double W can be done at 8 ohm.
So what you wrote is true if we use the right voltage trafo.
200VA 2x26V trafo doesn't have enough amp for 2x3 channel amp.
This is what you kind of wrote below.
But he uses a high voltage, low amp trafo.
Not enough. This is my oppinion.
Here is another update of the build.
( Prashanth, hope you are reading this post.
)I just added a Preamp with a 3 band Equalizer ( designed by Construyasuvideorockola.com and fixed my problem with that by our respected Moderator Mooly) at the input.
I also adjusted the X-over levels a little and..........
And Big sound! Dramatic change!!
The output is way more than adequate for my listening environment.
Bass response is definitely nicer/deeper than TDA2050, even with my "not-so-technically" designed DIY floor-standers.
Mid and high are also pretty excellent as expected even with cheap unbranded Chinese tweeters. Well, perhaps this is the magic of active amp.
Great and loud sound even with a single transformer (4 ampere) and six 4700 uFd caps in my listening environment.
I will post more after adding two more 4700uFd caps at second stage of the PSU.
I was wondering how you would adjust the levels, for the High, Mid, and Low amps, especially if the Low is driving 8 Ohms and the Mid and High are driving 4 Ohms.
It seems like you might want to start with about half as much input signal, for the amps with 4-Ohm speakers, as a starting point for the equalization process.
It seems like you might want to start with about half as much input signal, for the amps with 4-Ohm speakers, as a starting point for the equalization process.
The OP said;
It is a 200VA transformer and, as AndrewT and I have said repeatedly, it supplies more than enough power for the intended purpose. AndrewT has explained why in detail and I have a working example to demonstrate the case. Please, any more attempts to mislead the OP can only be construed as trolling.
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Yeah but I think that we were also discussing the possibility that the OP might try to use only ONE of those transformers, to drive all six amps.
He could do that but then he might have trouble with the theoretical maximum output power ratings, although I doubt that he would have any trouble with real music.
He could do that but then he might have trouble with the theoretical maximum output power ratings, although I doubt that he would have any trouble with real music.
Here is another update of the build.
( Prashanth, hope you are reading this post.
I just added a Preamp with a 3 band Equalizer ( designed by Construyasuvideorockola.com and fixed my problem with that by our respected Moderator Mooly) at the input.
I also adjusted the X-over levels a little and..........
And Big sound! Dramatic change!!
The output is way more than adequate for my listening environment.
Bass response is definitely nicer/deeper than TDA2050, even with my "not-so-technically" designed DIY floor-standers.
Mid and high are also pretty excellent as expected even with cheap unbranded Chinese tweeters. Well, perhaps this is the magic of active amp.
Great and loud sound even with a single transformer (4 ampere) and six 4700 uFd caps in my listening environment.
I will post more after adding two more 4700uFd caps at second stage of the PSU.
Coool!!
Was that with one transformer or two?
First, my sincere apology to all for this squabbling that has arisen out of my inadvertent use of "I am using two transformers....".
Kindly interpret that as "I am going to use...". ( Sorry, English is not my First Language).
This project is still under construction with the kind help from all of you.
After Sir Andrew taught me the proper "Grammatical" Ground connection, I added all the six amps to only one Transformer ( 4 amp only, and giving an output of 23-0-23 VAC approximately, just measured it with all the chips connected) just for a test. And also I was concerned about the size of the electronic enclosure since I had to put everything in the same cabinet due to space constraint in my listening room.
And found it is working with great sound with only one transformer even if it is perhaps theoretically impossible! So I reported that to all of you.
And right now I am just monitoring the sound ( using only one transformer) by ear and also keeping a frequent eye on the multi-meter reading.
I guess I have mentioned this at post #53. Still I am sorry for the confusion.
I have still one transformer and the 6 sets of 4700 uFd caps set left unused.
But I will have to use them too as I understood from this healthy debate, highly beneficial to a noob like me.
So finally it will be two 4 ampere transformers and twelve caps for the whole six sets of amps.
Thank you all.
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I followed this article to build my X-over.
Silicon Chip Online - Active 3-Way Crossover for Loud Speaker Systems
I possess neither of the two gadgets ( "an audio oscillator and a digital multimeter with an AC frequency response to 20kHz or better.") as mentioned there to set the X-over level.
So I added 3 dual ganged 100k potentiometer to set the level on the fly using my ear. This kinda helps me as I have no great speakers, just cheap Chinese ones with no specific data available about them.
Here is how I do it.
I play some of my favourite songs lowering the signal with no Equalizer etc. Then I adjust/ balance the individual Low, Mid and High levels until I am satisfied.
But still, the sound is pretty awesome and this adjustment works great with every song.
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