I have a 600VA Transformer with dual secondaries (40V - 0V, 40V - 0V). Would like to conect 4 LM3886 (2 paralleled per channel) to this transformer, as it has 600VA.
With single full wave bridge rectifier at each seconday pair (40 - 0), and after 12,000uF caps, I should have around 55V - 0V.
Now, can I use the 55V - 0V to connect to the LM3886 in a single supply rail fashion instead of the +/-30V dual supply rail? In this way, I am not exceeding the 84V max, right?
I do not want to unwind/reverse wind the windings on the transformer to get a reduced DC voltage, as it would be easier just to get the correct transformer.
But thought this single supply rail setup may work...
With single full wave bridge rectifier at each seconday pair (40 - 0), and after 12,000uF caps, I should have around 55V - 0V.
Now, can I use the 55V - 0V to connect to the LM3886 in a single supply rail fashion instead of the +/-30V dual supply rail? In this way, I am not exceeding the 84V max, right?
I do not want to unwind/reverse wind the windings on the transformer to get a reduced DC voltage, as it would be easier just to get the correct transformer.
But thought this single supply rail setup may work...
Good deal, but...
The datasheet doesn't give a whole lot of info - unless I am not looking at the correct datasheet...a simple schematic is shown, and no indication of what the V+ range could be (I guessed it to be < 84 Volts)
At far as midpoint voltgae for biasing input, could you elaborate a bit more? Are you referring to the components off of Pin 7 (usually grounded for dual voltage operation?)
Looks to be a few more components for the single rail setup...anyone have any experience on how it sounds compared to dual rails?
The datasheet doesn't give a whole lot of info - unless I am not looking at the correct datasheet...a simple schematic is shown, and no indication of what the V+ range could be (I guessed it to be < 84 Volts)
At far as midpoint voltgae for biasing input, could you elaborate a bit more? Are you referring to the components off of Pin 7 (usually grounded for dual voltage operation?)
Looks to be a few more components for the single rail setup...anyone have any experience on how it sounds compared to dual rails?
single supply
Your voltage will become the maximum figure specified by LM , if 84V it will be 84V/0 ground. The chip will loose a great deal of performance, single supply will tripple components add an out put capacitor to block DC and create a mid voltage point for bias, and the ability to parellel the chips effectivley will be lost.
Your voltage will become the maximum figure specified by LM , if 84V it will be 84V/0 ground. The chip will loose a great deal of performance, single supply will tripple components add an out put capacitor to block DC and create a mid voltage point for bias, and the ability to parellel the chips effectivley will be lost.
Forget Single Supply, how 'bout a Voltage Divider?
I am ready to deep six the Single supply idea, but what about a two - resistor voltage divider? I would have approximately (recified) 27V with a 55V input... I know it's a waste of energy, but hey...why not try...
Any dealings/opinions on this route? I can't see a reason as to why not...
I would really like to use these transformers, and +/- 27V and 300VA/channel would still work out fine.
I am ready to deep six the Single supply idea, but what about a two - resistor voltage divider? I would have approximately (recified) 27V with a 55V input... I know it's a waste of energy, but hey...why not try...
Any dealings/opinions on this route? I can't see a reason as to why not...
I would really like to use these transformers, and +/- 27V and 300VA/channel would still work out fine.
Go ahead.
Single supply can be just as good as dual supply.
I think people are afraid of single supply for no valid reason.
Like they see some ghost .....
Single supply is better in some parameters than dual supply.
With several rails, there are more paths for garbage to enter circuit.
Was not long ago best amplifiers in world were single supply
with output electrolytic capacitors.
Designed by some wellknown world famous amplifier constructors.
And those electrolyts was not of the quality we have today.
I have built a super sounding headphone amplifier
with 12 volt single supply and using an 1.000uF axial ROE for output.
It is the best sound I have ever heard.
Single supply can be just as good as dual supply.
I think people are afraid of single supply for no valid reason.
Like they see some ghost .....
Single supply is better in some parameters than dual supply.
With several rails, there are more paths for garbage to enter circuit.
Was not long ago best amplifiers in world were single supply
with output electrolytic capacitors.
Designed by some wellknown world famous amplifier constructors.
And those electrolyts was not of the quality we have today.
I have built a super sounding headphone amplifier
with 12 volt single supply and using an 1.000uF axial ROE for output.
It is the best sound I have ever heard.
Voltage Regulator
I was looking into the LM317/337 voltage regulator setup and I have exceeded the Amp limit (1A) and the LM350 is only marginally better at 3A...
Oh well, looks like I need to get another transformer, as +/-55VDC won't work...
Any other thoughts before I go purchase another toroidal transformer?
I was looking into the LM317/337 voltage regulator setup and I have exceeded the Amp limit (1A) and the LM350 is only marginally better at 3A...
Oh well, looks like I need to get another transformer, as +/-55VDC won't work...
Any other thoughts before I go purchase another toroidal transformer?
Let me back up here...
Looking for +/- 27 - 30VDC for 4 ohm speakers. 150VA/amp module and 4 total modules - paralleled for 2 channel operation.
Transformer is 600VA, 40VAC -0, 40VAC -0 secondaries, getting 55VDC - 0, 55VDC - 0 after rectifier/12000uF caps.
Trying to see if I could "post rectified split" each +/- 55VDC - 0 rail to get two +/-27VDC - 0 ...
So in summary, four rails of +/-27VDC - 0 @ 150VA off this transformer via "split"...possible?
Looking for +/- 27 - 30VDC for 4 ohm speakers. 150VA/amp module and 4 total modules - paralleled for 2 channel operation.
Transformer is 600VA, 40VAC -0, 40VAC -0 secondaries, getting 55VDC - 0, 55VDC - 0 after rectifier/12000uF caps.
Trying to see if I could "post rectified split" each +/- 55VDC - 0 rail to get two +/-27VDC - 0 ...
So in summary, four rails of +/-27VDC - 0 @ 150VA off this transformer via "split"...possible?
I attach
the single supply LM3886 circuit, from datasheet.
The supply is pin1 and pin4.
+V and Ground.
You need input( 2.2 - 10 uF ) and output ( 4700uF ) caps.
A divider 91kOhm - 100kOhm to bias input.
Also a transistor feeding 'GND' pin #7.
Several of components are optional.
See datasheet comments for more info.
the single supply LM3886 circuit, from datasheet.
The supply is pin1 and pin4.
+V and Ground.
You need input( 2.2 - 10 uF ) and output ( 4700uF ) caps.
A divider 91kOhm - 100kOhm to bias input.
Also a transistor feeding 'GND' pin #7.
Several of components are optional.
See datasheet comments for more info.
Attachments
Don't omit the Ci cap for single supply
A point worth mentioning. When I first tried to run the LM3886 on a single supply without the optional components it didn't work until I spotted the mistake on National's datasheet. The capacitor marked Ci is not optional for the single supply version, without that the amp will not work.
A point worth mentioning. When I first tried to run the LM3886 on a single supply without the optional components it didn't work until I spotted the mistake on National's datasheet. The capacitor marked Ci is not optional for the single supply version, without that the amp will not work.
I'd go with the single supply, and with your transformer you can get one winding for each channel. There's an awful lot to recommend it: It's much easier to know where your earth is, what's on V+ is the music itself, not just part of it and the additional components are things like coupling capacitors which you would probably have already. You also lose components in places. Like you can lose two diodes and one Reservoir cap (obviously not if you do two supplies).
It's also a good intellectual exercise. Just be careful with the mid voltage as anything on that becomes part of your signal. Two resistors, IMHO, is not good enough - it's 6dB PSR, which is not great.
It's also a good intellectual exercise. Just be careful with the mid voltage as anything on that becomes part of your signal. Two resistors, IMHO, is not good enough - it's 6dB PSR, which is not great.
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