Coincidentally, just retired my 1982 C-4
I've been lurking here on and off for a few years, lusting over everyone's 250's, so I guess it's about time I post something worthwhile.
I just retired a C-4 I bought new in 1982 around the same time I bought my (since reconed) L112's. After many years of faithful service in my main, and then, 2-channel setup, the selector, balance and volume pots got so scratchy and worn out, it had to go. I also recently scored a set of working, original owner, L56's on CL for $40 (wohoo!) that deserved better treatment than the C-4 was giving the crappy blose 301's (old style) in my home office. Yea, don't laugh, someone gave them to me.
The frequency turnover controls are for the pre-amp's parametric equalization. The C-4 is a great, vintage mid-end Yamaha pre-amp. Good, clean specs. I'm sorry to see mine go, but it's not worth repairing. Just like our beloved vintage JBL's, I hold onto vintage Yamaha gear dearly and replaced the C-4 with a 10 year old Yami receiver (oldest I could find with a remote.) I still run it through the matching M-4 amp (120w/ch), and also route my Yamaha surround receiver main fronts through an old M-80 (250w/ch class a/b) amp that feeds the L112's. For mid range gear, it's tough to beat.
http://www2.yamaha.co.jp/manual/pdf/...h/SepA/C-4.pdf
Just scanned my manual for you.
It's 24MB as I cranked up the res on the schematic page. Do you have an FTP site I can put it somewhere or will your e-mail accept such a large file?
You have a great 2-channel pre-amp there. I almost cried when the phono section on mine went out. Without the cartridge load and impedance matching, my AV amp just doesn't sound the same. I'm still looking to replace it.
Uploading to a sharing site now. I'll PM you with the info.
You let me know if you ever want to sell that C-4. I've got a line on a replacement, but can always use another/spare. I'm really just using it for the phono section as it's:
1. Adjustable to match the cartridge.
2. My AV rcvr doesn't rec-out the phono so I can't loop in my EQ and DBX-3BX with it.