Unregulated supply for class d - 3255 and 3251
I have the 3e 3255 and 3251 3ch. boards and I wish to make an unregulated supply for them both.
I know smps are more common but I can hear the pwm from my MW 48V for the 3255 and I would be adding another MW smps for the 3251. I would like to try building a toroidal psu for interest value as much as anything. This is an addictive hobby!
I have a 430va toroid with 30v and 25v secondaries so will be nice for the amps when rectified....if a little low from the 30v for the 3255.
I ordered 2 of these rectifier smoother boards. One for each amp.
HiFi Single Power Supply Rectifier Filter Board Kit For 1969 Amplifier PSU | eBay
They feature 40000uf per board using Nover gold caps. I understand there are some whom don't like these caps.
Should I stick with that much capacitance or may be lower the values with some higher quality caps?
If I stick to the 40000 per board, and these 2 boards will come from one toroid, it will all get powered up at once.
Will in rush amperage be an issue into 80000uf from 430VA?
Can one switch out the secondaries...ie turn off. As to have the ability to have the 2 channel 3255 powered up without the 3 channel 3251 would be handy for me. But they will come from one toroid.
Any advice always appreciated.
I have the 3e 3255 and 3251 3ch. boards and I wish to make an unregulated supply for them both.
I know smps are more common but I can hear the pwm from my MW 48V for the 3255 and I would be adding another MW smps for the 3251. I would like to try building a toroidal psu for interest value as much as anything. This is an addictive hobby!
I have a 430va toroid with 30v and 25v secondaries so will be nice for the amps when rectified....if a little low from the 30v for the 3255.
I ordered 2 of these rectifier smoother boards. One for each amp.
HiFi Single Power Supply Rectifier Filter Board Kit For 1969 Amplifier PSU | eBay
They feature 40000uf per board using Nover gold caps. I understand there are some whom don't like these caps.
Should I stick with that much capacitance or may be lower the values with some higher quality caps?
If I stick to the 40000 per board, and these 2 boards will come from one toroid, it will all get powered up at once.
Will in rush amperage be an issue into 80000uf from 430VA?
Can one switch out the secondaries...ie turn off. As to have the ability to have the 2 channel 3255 powered up without the 3 channel 3251 would be handy for me. But they will come from one toroid.
Any advice always appreciated.
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A linear unregulated power supply I guess is a bit of a contradiction. "Linear" indicates that it uses a linear regulator, "unregulated" that there is no regulator. Sorry, just a small detail.
Seems like nice rectifier/capacitor boards. More than generous with 40000uF per board. I would stay with the Nover capacitors until you are convinced that other capacitors will clearly improve SQ.
Four 10000uF capacitors in parallel per amplifier is very generous and probably more than you will have benefit from. On the inrush current, it's in the gray area. I would start with only two 10000uF in each board and see how that works. You can quickly add the two remaining capacitors.
The transformer has one 30Vac (appr. 45Vdc) winding and one 25Vac (appr. 37Vdc) winding?
Yes, you can switch in the 30V winding without the 25V winding being used or the other way around if that is what you mean.
NB: I just studied the power board again and it seems to be a symmetrical voltage power board. Your TPA325x boards probably use only a single supply voltage? You can use these boards with a slight modification.
Seems like nice rectifier/capacitor boards. More than generous with 40000uF per board. I would stay with the Nover capacitors until you are convinced that other capacitors will clearly improve SQ.
Four 10000uF capacitors in parallel per amplifier is very generous and probably more than you will have benefit from. On the inrush current, it's in the gray area. I would start with only two 10000uF in each board and see how that works. You can quickly add the two remaining capacitors.
The transformer has one 30Vac (appr. 45Vdc) winding and one 25Vac (appr. 37Vdc) winding?
Yes, you can switch in the 30V winding without the 25V winding being used or the other way around if that is what you mean.
NB: I just studied the power board again and it seems to be a symmetrical voltage power board. Your TPA325x boards probably use only a single supply voltage? You can use these boards with a slight modification.
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Hey thanks FF for your input.
Sorry my learning curve is steep.....unregulated supply it is from now!
The board has a jumper to add if using single supply.
My boards are indeed single input...well I think so +/- DC.....'normal dc' as I might call it..?!
The toroid actually has a 13.8 , 25 and 2 at 30v. Also different primaries for 220, 230 and 240. I generally have 248 here. Thought about using the 220 input to get more out the secondaries series but it will over volt the 25v for the 3251.
So it is ok to add a suitably rated switch to turn off some of the secondaries...great.
Sorry my learning curve is steep.....unregulated supply it is from now!
The board has a jumper to add if using single supply.
My boards are indeed single input...well I think so +/- DC.....'normal dc' as I might call it..?!
The toroid actually has a 13.8 , 25 and 2 at 30v. Also different primaries for 220, 230 and 240. I generally have 248 here. Thought about using the 220 input to get more out the secondaries series but it will over volt the 25v for the 3251.
So it is ok to add a suitably rated switch to turn off some of the secondaries...great.
For the switches it is OK. Change the switch setting when the power is OFF!
2 windings of 30V. If they are fully floating and not connected by a center-tap, you can use one winding per board. With a center tap it becomes more difficult.
I believe GB has 240V nominally. It is tempting to use the 220V primary but then you stress the core somewhat more and increase core losses. In order to get most out of the core, the manufacturer probably use it pretty close to where saturation starts. The manufacturer has to take account of variation in the grid voltage but not wrong use of the primary. I wouldn't do it.
2 windings of 30V. If they are fully floating and not connected by a center-tap, you can use one winding per board. With a center tap it becomes more difficult.
I believe GB has 240V nominally. It is tempting to use the 220V primary but then you stress the core somewhat more and increase core losses. In order to get most out of the core, the manufacturer probably use it pretty close to where saturation starts. The manufacturer has to take account of variation in the grid voltage but not wrong use of the primary. I wouldn't do it.
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