Hi everybody!
I'm a 19 years old EE student, and i've always loved music. I've built numerous cheap amplifiers, like the TDA2030, 2050, 7294, and built a few better ones, like an STK-056A, a JLH 10W, and now, i'm listening to a Hiraga Le Monstre 8W, with original SanKen transistors (2SC1116, 2SK747). Most recently i got a job as an intern, made some cash, and bought a pair of T+A Criterion T100s. And that's where the problems started.
I knew that the 3.5mm jack output of PCs don't really sound great, but i didn't notice it until i've bought new speakers. So yesterday i grabbed my parents broken ~15 years old CD player (Daewoo AMI-310), downloaded a manual for it, and started repairing. I've had to adjust the laser, rebuild the CD tray mechanics, replace motor power supply pass transistors and current limit resistors, and voila, it works now. The circuitry is freakin overcomplicated, with a cheapass LA4282 amplifier IC, big EQ board, and IMO unnecessary filter loops, but still, it sounded a lot better than my PC when i put some Vangelis into the player. So i did what i considered appropriate: fed a signal to my Le Monstre from the first opamp buffer output after the D/A converter. Results? My mind was blown. I mean, obviously it has a very cheap build quality, but finally i started to hear instruments instead of just music.
Now let's jump right into my project. The D/A in the Daewoo is a KDA0316 (with 2x OS filter in front of it), which is exactly the same as the LC7881. I've just scored a Sony CDP-270 for $25 with shipping. It has a CXD2551P 4x OS filter, an LC7881 D/A, and an M5204P output amplifier from Motorola. Do you have any ideas about how to improve the quality while using fairly inexpensve parts? I've been thinking about replacing digital Vdd caps for SANYO OSCON SEPC ones, and the analog Vdd ones for ELNA Tonerex caps. I'm thinking about buying a few Cornell Dubilier 940s or Russian PIO capacitors for decoupling the DAC output, which i'm gonna feed into OPA134s instead of the M5204P. Maybe i could optically isolate the whole DAC module, and build a completely separate PSU for it. Anyway, anything that happens with the player, i will post everything here ASAP.
I'm a 19 years old EE student, and i've always loved music. I've built numerous cheap amplifiers, like the TDA2030, 2050, 7294, and built a few better ones, like an STK-056A, a JLH 10W, and now, i'm listening to a Hiraga Le Monstre 8W, with original SanKen transistors (2SC1116, 2SK747). Most recently i got a job as an intern, made some cash, and bought a pair of T+A Criterion T100s. And that's where the problems started.
I knew that the 3.5mm jack output of PCs don't really sound great, but i didn't notice it until i've bought new speakers. So yesterday i grabbed my parents broken ~15 years old CD player (Daewoo AMI-310), downloaded a manual for it, and started repairing. I've had to adjust the laser, rebuild the CD tray mechanics, replace motor power supply pass transistors and current limit resistors, and voila, it works now. The circuitry is freakin overcomplicated, with a cheapass LA4282 amplifier IC, big EQ board, and IMO unnecessary filter loops, but still, it sounded a lot better than my PC when i put some Vangelis into the player. So i did what i considered appropriate: fed a signal to my Le Monstre from the first opamp buffer output after the D/A converter. Results? My mind was blown. I mean, obviously it has a very cheap build quality, but finally i started to hear instruments instead of just music.
Now let's jump right into my project. The D/A in the Daewoo is a KDA0316 (with 2x OS filter in front of it), which is exactly the same as the LC7881. I've just scored a Sony CDP-270 for $25 with shipping. It has a CXD2551P 4x OS filter, an LC7881 D/A, and an M5204P output amplifier from Motorola. Do you have any ideas about how to improve the quality while using fairly inexpensve parts? I've been thinking about replacing digital Vdd caps for SANYO OSCON SEPC ones, and the analog Vdd ones for ELNA Tonerex caps. I'm thinking about buying a few Cornell Dubilier 940s or Russian PIO capacitors for decoupling the DAC output, which i'm gonna feed into OPA134s instead of the M5204P. Maybe i could optically isolate the whole DAC module, and build a completely separate PSU for it. Anyway, anything that happens with the player, i will post everything here ASAP.
Last edited: