Hi all here...
So i'am building the Xmas amp. Xmas Amp - Dibya's TDA7293 by Jhofland
I just recieved the pcb's and waiting for 4pcs. 10.000uF ELNA capacitors to come for the PSU (This one)
The transformer are not ordered yet, but i expect to order one of Toroidy's 300VA audio grade (Same price as locally, but much better quality)
I did a lot of reading, and i ordred the capacitor's by using TNT audio's easy-to-read tables - I also took the basic schematic as ref. here. (Cool site btw.)
I'am having all kind's of resistors and wima's etc... etc.. in my stock.
I'am asking for advice here for bulding a very good psu delivering around +36vdc / 0 / -36vdc for the Xmas amp.
I did a lot of reading, but i still need some good advice's from you guy's here! 🙂
I know that PSU have been discussed a lot, and there are lot of design's around the net, but i still want to develop my own superduper one.
What do you think about the basic schematic?... Do i need some resistor's between the 10.000 capacitor's, like in Pass class A psu's ?
I'am open for all suggestion's, but i really would like a good psu in the end.
I have an Rigol DS1102 oscilloscope, and my modded Behringer soundcard to measure + ofcause some DMM's.
What do you think?
Howto improve?
Jesper.
EDIT :: QMR1, QM1, QM2, QM4, QM3, QMR2 are for capacitor's and resistors for snubbers (i use the Quasimodo rig.) - Donno the values yet ofcause!
This is just a starting mockup::
So i'am building the Xmas amp. Xmas Amp - Dibya's TDA7293 by Jhofland
I just recieved the pcb's and waiting for 4pcs. 10.000uF ELNA capacitors to come for the PSU (This one)
The transformer are not ordered yet, but i expect to order one of Toroidy's 300VA audio grade (Same price as locally, but much better quality)
I did a lot of reading, and i ordred the capacitor's by using TNT audio's easy-to-read tables - I also took the basic schematic as ref. here. (Cool site btw.)
I'am having all kind's of resistors and wima's etc... etc.. in my stock.
I'am asking for advice here for bulding a very good psu delivering around +36vdc / 0 / -36vdc for the Xmas amp.
I did a lot of reading, but i still need some good advice's from you guy's here! 🙂
I know that PSU have been discussed a lot, and there are lot of design's around the net, but i still want to develop my own superduper one.
What do you think about the basic schematic?... Do i need some resistor's between the 10.000 capacitor's, like in Pass class A psu's ?
I'am open for all suggestion's, but i really would like a good psu in the end.
I have an Rigol DS1102 oscilloscope, and my modded Behringer soundcard to measure + ofcause some DMM's.
What do you think?
Howto improve?
Jesper.
EDIT :: QMR1, QM1, QM2, QM4, QM3, QMR2 are for capacitor's and resistors for snubbers (i use the Quasimodo rig.) - Donno the values yet ofcause!
This is just a starting mockup::
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The resistors across the big caps are there for discharging them after the mains power is disconnected. They are chosen to be rather low power usage during normal operation, but still enough to discharge the capacitors after it's been turned off.
You don't want to touch any of those connections when they're charged.
The TDA7293 as a chip, is fairly robust. I wouldn't be afraid of testing the power supply with it as a load, so that you can measure the ripple of the circuit. Ripple or voltage changes due to load characteristics are expected, and this chip is built with that in mind already.
I would personally go for two good isolated switch mode supplies in series.
You don't want to touch any of those connections when they're charged.
The TDA7293 as a chip, is fairly robust. I wouldn't be afraid of testing the power supply with it as a load, so that you can measure the ripple of the circuit. Ripple or voltage changes due to load characteristics are expected, and this chip is built with that in mind already.
I would personally go for two good isolated switch mode supplies in series.
Thank's for answering @HumbleDeer
I will make some testing when i got the missing part's, and the transformer which i ordred today from Toroidy.
Let's see how it goes then.
Jesper.
I will make some testing when i got the missing part's, and the transformer which i ordred today from Toroidy.
Let's see how it goes then.
Jesper.
There is no need for dual diode bridge, and in fact they add impedance and voltage loose for the PSU.
Hey @Osvaldo de Banfield ...
I do this mainly because it always worked for me and Mr. Pass use this configuration in his amp's to avoid saturation in transformer.
But I can't say for sure if it's better or not in this setup, but I'll probably stick with two bridges.
Jesper.
The classic design works still better from the vacuum tube rectifiers era, agsin, less resistance and higher efficiency. But do it at your mode.
I also want to recommend double bridge if transformer has separate windings (NO CT). I heard from some experienced professionals that this technique gives best noise performance in amplifiers although the difference isn't huge. Anyway your schematic looks good but you have to figure out the values of those snubbers, without proper values they're useless. I always avoid small decoupling caps in parallel with big electrolytics.
Regards
Regards
Hey ...
I use the Quasimodo rig. for finding the right snubber values, when i have the transformer on hand that is 🙂
Is there any reason why to not use small decoupling cap's ? - I see this used everywhere.
Anyway i did some corrections on my schematic.
The Opt.1 & Opt.2 are just "extra" holes for extra parts (optional)
When i'am there i will make a handdrawn PCB for this.
Jesper.
