So maybe a strange way of going about things but I bought this whacking great toroidal trafo for my tpa3255 but I seem to be happy with it at 40 ish vdc from a 30vac trafo that is currently in situ.
So I have this 525va dual 35v secondary toroidal just begging to be used.
Had considered building a +/- dual psu for irs2092....or can anybody think of any more amps....class d or chip, that would lend itself to this big transformer.?
Maybe a powerful mono build for a subwoofer?!
So I have this 525va dual 35v secondary toroidal just begging to be used.
Had considered building a +/- dual psu for irs2092....or can anybody think of any more amps....class d or chip, that would lend itself to this big transformer.?
Maybe a powerful mono build for a subwoofer?!
You start with the speaker you are designing for.
+-35 is a bit lowish for 8 ohms. Peak voltage is 48, v^2/r for 8 ohms is 300 w, 600 for 4. Your transformer will limit that to 262
w per channel. That is 8 amps 4 ohm, 4 for 8. With top end On semi transistors (MJ21195/96) being good for about 5 amps soa @ 50 v, class AB you need 2 pairs OT for 4 ohm and 1 for 8. 2sc5200 are a little less potent, the ST chart is hard to read but maybe 3 amps soa for 100 ms? so 3 pairs 5200/1943 for 4 ohms 2 pairs for 8 ohms ?
That puts you directly in honeybadger territory. See the diyaudiostore in the banner up top.
If chip amp, buy a pcb. I tried a LM1875 point to point and it motorboated inexorably. All the boards for sale are split supply requiring an add on protection circuit. LM3886 is still too wimpy for this transformer. LME49811 was 300 w/ch: boards are being sold populated but with the IC out of production for 2 years I suspect the IC are counterfeit. Voltage is too high for the class D boards from parts-express. TDA7293 can handle this voltage but not that much wattage.
+-35 is a bit lowish for 8 ohms. Peak voltage is 48, v^2/r for 8 ohms is 300 w, 600 for 4. Your transformer will limit that to 262
w per channel. That is 8 amps 4 ohm, 4 for 8. With top end On semi transistors (MJ21195/96) being good for about 5 amps soa @ 50 v, class AB you need 2 pairs OT for 4 ohm and 1 for 8. 2sc5200 are a little less potent, the ST chart is hard to read but maybe 3 amps soa for 100 ms? so 3 pairs 5200/1943 for 4 ohms 2 pairs for 8 ohms ?
That puts you directly in honeybadger territory. See the diyaudiostore in the banner up top.
If chip amp, buy a pcb. I tried a LM1875 point to point and it motorboated inexorably. All the boards for sale are split supply requiring an add on protection circuit. LM3886 is still too wimpy for this transformer. LME49811 was 300 w/ch: boards are being sold populated but with the IC out of production for 2 years I suspect the IC are counterfeit. Voltage is too high for the class D boards from parts-express. TDA7293 can handle this voltage but not that much wattage.
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Intended use ? Budget ?
I'd consider a stereo ucd400 (or NC400 if you have the budget) with that transformer.
I'd consider a stereo ucd400 (or NC400 if you have the budget) with that transformer.
100W Ultimate Fidelity Amplifier
post #8557 has gerbers ad schematic that I used. Also gerbers from Sonal that have been provided and built about 2-3 pages prior i the same thread.
I would check out this thread, suggesting AX14 (2pr. 2SC5200/1943) or the one I built, FH11 (2pr. IRFP240/9240) - both have gerbers available and you can order from China in about 2 weeks start to finish. I think parts are ~$30/channel.
FH11 - green board pic
AX14 - red board pic - google "AX14 APEX" and you will find links to everything you need.
post #8557 has gerbers ad schematic that I used. Also gerbers from Sonal that have been provided and built about 2-3 pages prior i the same thread.
I would check out this thread, suggesting AX14 (2pr. 2SC5200/1943) or the one I built, FH11 (2pr. IRFP240/9240) - both have gerbers available and you can order from China in about 2 weeks start to finish. I think parts are ~$30/channel.
FH11 - green board pic
AX14 - red board pic - google "AX14 APEX" and you will find links to everything you need.
Attachments
Would something like an Avondale Qudos or possibly even there NCC300 amps be worth considering. I believe Les Wolstenholme of Avondale does sell bare boards.
I´ll do the Math for a standard Class AB amplifier.
IF you use a Class D one, add , say, 2V to available peak voltage.
You have +/-49V unregulated rails, which will drop about 15% under full load.
And substract 4V from your peak voltage to account for transistor drop and what´s lost across emitter resistors, you´ll end up with available 37.5V peak or 26,5V RMS.
So a Stereo amplifier with about 175W RMS per channel into 4 ohm or 350W into 8 ohm if bridged.
Not bad at all.
Slightly more power available if Class D.
This is a realistic and conservative estimate, which does not abuse your transformer.
Actual power amp schematic is not that important, pick whatever suits your fancy, like Enzo says: "the power amplifier is that thingie between the power supply and the speaker" 🙂
Your TPA3255 would even be more happy with your bigger transformer. Just connect both 35 Vac secondaries in parallel (observe correct phasing!) and you'll get about 50 Vdc. The TPA3255's maximum supply voltage is 53.5 Vdc. Hence both the TPA and the tranny will happily work with each other.
Best regards!
Best regards!
Thanks for all the informed replies.
I should have stated a budget...and this does have a fairly low budget I guess. I'm thinking ebay/Ali Amps or maybe bare PCBs that I shall populate. 30 to 50gbp per channel max I suppose although I do have 2 x psu boards with rectification and 40kuf smoothing to use.
I don't really have a particular intent or application in mind ...as I am just looking to see what I can build with this trafo. This DIY audio hobby has bitten me and I am keen to build stuff. Even if it may not have a home yet. I appreciate the comment on designing the amp around the speaker, but this isn't happening here! You are talking to a guy that has 3255 powering stereo 3.5" fullrange.....but they seem to love it.
The Avondale and Hypex are more than I intend to spend, although I dont know a price for the Avondale bare boards. I looked on the site but they arent listed .
Lm3886 as mentioned above is an amp that is on my radar but alas this trafo is too much.
The Ultimate Fidelity is maybe perhaps a little too involved a build for me for now. I had quite a game sorting out my DCG3 build and had to enlist a 3rd party to assist (luckily a very obliging member on here)...and so that all maybe more than I ought to take on. I have no means of fault finding apart from DMM and limited knowledge.!
And so to 3255 @ 50vdc or so from this trafo. I stopped myself from doing just that as I thought the 3245 would be happier (cooler) at 40vdc and that the THD would be a little less pushed. Maybe just conjecture.
I shall think on and let you know what I decide to do!
Thanks again.
I should have stated a budget...and this does have a fairly low budget I guess. I'm thinking ebay/Ali Amps or maybe bare PCBs that I shall populate. 30 to 50gbp per channel max I suppose although I do have 2 x psu boards with rectification and 40kuf smoothing to use.
I don't really have a particular intent or application in mind ...as I am just looking to see what I can build with this trafo. This DIY audio hobby has bitten me and I am keen to build stuff. Even if it may not have a home yet. I appreciate the comment on designing the amp around the speaker, but this isn't happening here! You are talking to a guy that has 3255 powering stereo 3.5" fullrange.....but they seem to love it.
The Avondale and Hypex are more than I intend to spend, although I dont know a price for the Avondale bare boards. I looked on the site but they arent listed .
Lm3886 as mentioned above is an amp that is on my radar but alas this trafo is too much.
The Ultimate Fidelity is maybe perhaps a little too involved a build for me for now. I had quite a game sorting out my DCG3 build and had to enlist a 3rd party to assist (luckily a very obliging member on here)...and so that all maybe more than I ought to take on. I have no means of fault finding apart from DMM and limited knowledge.!
And so to 3255 @ 50vdc or so from this trafo. I stopped myself from doing just that as I thought the 3245 would be happier (cooler) at 40vdc and that the THD would be a little less pushed. Maybe just conjecture.
I shall think on and let you know what I decide to do!
Thanks again.
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In that budget maybe this ? Hifimediy T3S Jantzen cap Or this ? TA3020 Audio Amplifier v3b | Connex Electronic
Never tried those myself.
Never tried those myself.
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