I'm planning to build Rod Elliot's 60-80W amp (project 3A) to hook up to my computer, since the sound card amp, well, sucks. It's going in my bedroom, so it doesn't need to be *that* loud, but I want decent quality (but again, since it'll be mostly fed from MP3's, it doesn't have to be that great, again).
Where can I get decent metal cases in Sydney, Australia? I'd really like to to be strong enough to support my monitor, too, but that's just a bonus. So far, the best I've come up with are plastic instrument cases... but since thing is going to be running in close proximity to my computer/monitor/network, I'd really, really like shielding...
If I'm not running at full power, will I be ok with the 160VA 25-0-25 toroid? Or should I spend the extra money on the 300VA? Will it make any difference at all? What about recommended filter capacitor sizes? If I buy the bigger transformer, can I get away with smaller capacitors (keeping the same amplifier, anyway).
I mainly ask because the 50W control amp in EA June-July 1996 only used the 160VA, but I see a lot of designs recommending more.
How can I estimate the power handling of my speakers? They're old 'PYE Model SP 3' ones, inner volume is about 30 litres, sealed box, chipboard. Woofer is about 8 inches, but the midrange and tweeter have some funny cover over most of them, so I can't measure them without disassembling the box. They're the next job for rebuilding, once I've done the amp
I might do the speaker wire anyway, since it's pretty pathetic -
insulation outer diameter is about 1.5mm.
Component mounting - can I get away with stripboard/Veroboard? Or should I spend the extra money for the PCB's? I can manage stripboard layout without any problems (I used to prototype a lot of digital circuits), but will the tracks handle the current needed by an amp? Or should I do dodgy things like solder copper wire along the length of the track? I was considering wiring it point-to-point, but I think it's getting a little complex for that to be practical...
Any layout guidelines for preventing oscillation or other problems? Will there be any problems with the +/-35V rails on stripboard (apart from having to re-drill holes so that the cable actually fits into the board)?
I'm planning to use MJE3055/MJE2955's - will this be a problem, so long as I keep the output power down? I really do like the idea of $1.70 output drivers - I can kill them and not care.
There's a good chance that whatever hardware I use for this amp will be reused in my next amp anyway, so I'd like to get it right now...
Final question: transformer inputs are non-polarised, right? I don't see any reason why they would be, but I'd just like to make absolutely sure...
High-power amps are a nice change from low-voltage digital
electronics...
Thanks for your comments.
Ian
Where can I get decent metal cases in Sydney, Australia? I'd really like to to be strong enough to support my monitor, too, but that's just a bonus. So far, the best I've come up with are plastic instrument cases... but since thing is going to be running in close proximity to my computer/monitor/network, I'd really, really like shielding...
If I'm not running at full power, will I be ok with the 160VA 25-0-25 toroid? Or should I spend the extra money on the 300VA? Will it make any difference at all? What about recommended filter capacitor sizes? If I buy the bigger transformer, can I get away with smaller capacitors (keeping the same amplifier, anyway).
I mainly ask because the 50W control amp in EA June-July 1996 only used the 160VA, but I see a lot of designs recommending more.
How can I estimate the power handling of my speakers? They're old 'PYE Model SP 3' ones, inner volume is about 30 litres, sealed box, chipboard. Woofer is about 8 inches, but the midrange and tweeter have some funny cover over most of them, so I can't measure them without disassembling the box. They're the next job for rebuilding, once I've done the amp
I might do the speaker wire anyway, since it's pretty pathetic -
insulation outer diameter is about 1.5mm.
Component mounting - can I get away with stripboard/Veroboard? Or should I spend the extra money for the PCB's? I can manage stripboard layout without any problems (I used to prototype a lot of digital circuits), but will the tracks handle the current needed by an amp? Or should I do dodgy things like solder copper wire along the length of the track? I was considering wiring it point-to-point, but I think it's getting a little complex for that to be practical...
Any layout guidelines for preventing oscillation or other problems? Will there be any problems with the +/-35V rails on stripboard (apart from having to re-drill holes so that the cable actually fits into the board)?
I'm planning to use MJE3055/MJE2955's - will this be a problem, so long as I keep the output power down? I really do like the idea of $1.70 output drivers - I can kill them and not care.
There's a good chance that whatever hardware I use for this amp will be reused in my next amp anyway, so I'd like to get it right now...
Final question: transformer inputs are non-polarised, right? I don't see any reason why they would be, but I'd just like to make absolutely sure...
High-power amps are a nice change from low-voltage digital
electronics...
Thanks for your comments.
Ian