Hi, my name is Garrett and this is my first post. There is a wealth of knowledge on this forum, so I was hoping some members could help me out.
I have an old TOA RX-212 board and can't afford anything better, but I can hopefully make this one better! I have already cleaned the sin out of all contacts, connections, pots, etc. and i'm going to recap the power supply (exact same power supply as the 16 channel version, but my board has 12 channels) and recap electrolytics in the signal chain.
I use the board every month to do live sound for shows my neighbors throw, but there are a couple problems with the board that I want to fix. Things like hiss at higher gain, no real soul or weak low end; basically it's kind of a wimpy board but has potential.
It has four BA4558 OP Amps and two 2SC2021 BJTs in the mic/line preamps. Now... I understand how to design with tubes (graphing out the load lines for biasing etc.) but Transistors and OP Amps I am helpless with. I know one or two things: like these 4558's should have had decoupling caps from power rails to GND. But I'm at a loss after that. The two things I want most out of this project is a better board and the understanding of why and how the modifications made it a better board. I see a couple of these TOA's come up from time to time so I'll document everything with pictures in case this whole thing can help someone else too…
And for reference, here is a link to a schematic for…
Channel strip
http://www.flickr.com/photos/87007682@N03/8728635608/in/photostream/
Left out
http://www.flickr.com/photos/87007682@N03/8728636470/in/photostream/
Right out
http://www.flickr.com/photos/87007682@N03/8727516723/in/photostream/
Power Supply
http://www.flickr.com/photos/87007682@N03/8727516403/in/photostream/
It's best to view them in the Large 2048 x 1448 option. Any and all help would be greatly appreciated! I really just want to be able to take what I learn from this and be able to apply it to other equipment in different ways. I'm trying the best I can with what I have and tons of money for nice gear is not something I have. Besides it feels so much better to use gear you made/mod yourself, especially when it turns out well.
Okay off to do more research on OP Amps...
I have an old TOA RX-212 board and can't afford anything better, but I can hopefully make this one better! I have already cleaned the sin out of all contacts, connections, pots, etc. and i'm going to recap the power supply (exact same power supply as the 16 channel version, but my board has 12 channels) and recap electrolytics in the signal chain.
I use the board every month to do live sound for shows my neighbors throw, but there are a couple problems with the board that I want to fix. Things like hiss at higher gain, no real soul or weak low end; basically it's kind of a wimpy board but has potential.
It has four BA4558 OP Amps and two 2SC2021 BJTs in the mic/line preamps. Now... I understand how to design with tubes (graphing out the load lines for biasing etc.) but Transistors and OP Amps I am helpless with. I know one or two things: like these 4558's should have had decoupling caps from power rails to GND. But I'm at a loss after that. The two things I want most out of this project is a better board and the understanding of why and how the modifications made it a better board. I see a couple of these TOA's come up from time to time so I'll document everything with pictures in case this whole thing can help someone else too…
And for reference, here is a link to a schematic for…
Channel strip
http://www.flickr.com/photos/87007682@N03/8728635608/in/photostream/
Left out
http://www.flickr.com/photos/87007682@N03/8728636470/in/photostream/
Right out
http://www.flickr.com/photos/87007682@N03/8727516723/in/photostream/
Power Supply
http://www.flickr.com/photos/87007682@N03/8727516403/in/photostream/
It's best to view them in the Large 2048 x 1448 option. Any and all help would be greatly appreciated! I really just want to be able to take what I learn from this and be able to apply it to other equipment in different ways. I'm trying the best I can with what I have and tons of money for nice gear is not something I have. Besides it feels so much better to use gear you made/mod yourself, especially when it turns out well.
Okay off to do more research on OP Amps...
