hi guys,
i've found my way here from the DIYStompboxes forum. i'm attempting to build my first solid-state amp - i'm not new to building effects or maintaining SS/tube amps, but this is my first amp build so i wasn't sure if this belonged here or in the Newcomer's Forum. i annoy the guys at DIYstompboxes with my confusion enough as it is without going off-topic. lol
anyway, here's the lo-down: i have a working preamp, transformer and presumably-working power filter/rectifier section, but my power amp section is noisy, distorted and clearly isn't working properly. i'm using the layout & schematic from here: http://www.coldcity.com/index.php/hybrid-guitar-amp/, which is more or less based on the TDA2030 datasheet. i started out with an old TDA2030, which i presumed was broken so i scored a few LM1875s. to the best of my understanding, they're more or less interchangeable (even if not too ideal).
after some issues with the negative supply rail being too low compared to the positive rail (as in closer to 0), which i think (or hope) i tracked down to a loose connection on my power filter, i'm still having problems with noise and general dysfunction. granted, i'm missing a coupla 2W 100R resistors to clean up the supply a bit, so there'll inevitably be some noise until i buy some tomorrow, but i'm pretty sure that's not the only source of noise. also, last i checked i'm getting +/-10V, which is too low given that the supply is +/-18V. for the record, the voltage going down to 10V is a recent development, as it was always at 18 prior to fixing the power filter. oh, and the heatsink gets far too hot. TDP should be adequate - i'm a computer nerd so i'm fairly confident it's big enough (not to mention it came from an old amp which itself used an 1875).
as i say, my experience is mostly with effects, and i'm a bit clueless with how to proceed here. no obvious solder bridges, tried a coupla chips (only have 1 left
), everything's grounded... nada. any help would be really appreciated!
cheers
i've found my way here from the DIYStompboxes forum. i'm attempting to build my first solid-state amp - i'm not new to building effects or maintaining SS/tube amps, but this is my first amp build so i wasn't sure if this belonged here or in the Newcomer's Forum. i annoy the guys at DIYstompboxes with my confusion enough as it is without going off-topic. lol
anyway, here's the lo-down: i have a working preamp, transformer and presumably-working power filter/rectifier section, but my power amp section is noisy, distorted and clearly isn't working properly. i'm using the layout & schematic from here: http://www.coldcity.com/index.php/hybrid-guitar-amp/, which is more or less based on the TDA2030 datasheet. i started out with an old TDA2030, which i presumed was broken so i scored a few LM1875s. to the best of my understanding, they're more or less interchangeable (even if not too ideal).
after some issues with the negative supply rail being too low compared to the positive rail (as in closer to 0), which i think (or hope) i tracked down to a loose connection on my power filter, i'm still having problems with noise and general dysfunction. granted, i'm missing a coupla 2W 100R resistors to clean up the supply a bit, so there'll inevitably be some noise until i buy some tomorrow, but i'm pretty sure that's not the only source of noise. also, last i checked i'm getting +/-10V, which is too low given that the supply is +/-18V. for the record, the voltage going down to 10V is a recent development, as it was always at 18 prior to fixing the power filter. oh, and the heatsink gets far too hot. TDP should be adequate - i'm a computer nerd so i'm fairly confident it's big enough (not to mention it came from an old amp which itself used an 1875).
as i say, my experience is mostly with effects, and i'm a bit clueless with how to proceed here. no obvious solder bridges, tried a coupla chips (only have 1 left
), everything's grounded... nada. any help would be really appreciated!cheers