manfromplanetx137
Member
- Joined
- Nov 13, 2006
- Messages
- 11
This is my 1st post here and am looking towards you guys for a little advice. I came across a Yamaha RM800 24 ch mixer that I purchased for a very good price locally. I really like the switching options and the flexibility of the mixer. Well of course my cheap mixer had a couple of noisy switches and eventually<last weekend> I took it apart to clean the switches <which is a whole other story> anyway when I took this apart I was amazed at its construction. I expected to see a single board or 2 with all the switches and pots and faders on it with surface mount components and all... sort of Be;;inger like...
BUT to my surprise each channel has its own single sided circuit board that runs the length of the channel and has electrolytics, mylar caps, ICs and what appear to be 1/4 watt resistors... I am not sure if they are metal or not. All the board are hooked together with a big ribbon cable that end up over in the mixdown section and there are 2 different types of input boards and A and B board with mic inputs, and then aux and mix boards these all feed into.
Anyway I was surprised that this was built this way and started to pull things apart and looked at them. The A and B board look to be fairly simple with a transistor front end and then ICs in the preamp, EQ and then out to the aux and etc. It looks like everything is pretty good components with the exception of the JRC4558D IC chips on these channels they also have JRC2086DD. Now I think that the 2086s are OK chips but things may sound better if I replaced the 4558s with JRCor ??? 5532 OP amps as these are a lot cleaner and better sounding.I havent taken any of the aux, buss or mix boards out but I am assuming they also have a 4558 or 2 on them.
My main question here is I beleive the 5532 is a direct replacement for these 4558s would it be worth my time to go thru and replace the 60 or so chips with the 5532s and what maker of chip should I look for. Also is the 2086DD and OK chip... it looks like a low noise and high slew rate amp, or is there a better solution to that, there are about 30 of those.
Am I going to be wasting my time with this project and only see minmal returns or do you guys and gals think it could be worth doing this. It would be a bit of work to change all of the 4558s but I think I could make it thru that...but much more than that... like a new power supply or any too much cap replacement of circuit reconfig is going to be a bit much.
I am looking to you hardcore highend DIYers for some direction...
I also have some pics pf this thing taken apart that if anyone is interested in will pos. and if I go ahead with mods recommended I will try to document the results and procedure.
Thanks
Larry
BUT to my surprise each channel has its own single sided circuit board that runs the length of the channel and has electrolytics, mylar caps, ICs and what appear to be 1/4 watt resistors... I am not sure if they are metal or not. All the board are hooked together with a big ribbon cable that end up over in the mixdown section and there are 2 different types of input boards and A and B board with mic inputs, and then aux and mix boards these all feed into.
Anyway I was surprised that this was built this way and started to pull things apart and looked at them. The A and B board look to be fairly simple with a transistor front end and then ICs in the preamp, EQ and then out to the aux and etc. It looks like everything is pretty good components with the exception of the JRC4558D IC chips on these channels they also have JRC2086DD. Now I think that the 2086s are OK chips but things may sound better if I replaced the 4558s with JRCor ??? 5532 OP amps as these are a lot cleaner and better sounding.I havent taken any of the aux, buss or mix boards out but I am assuming they also have a 4558 or 2 on them.
My main question here is I beleive the 5532 is a direct replacement for these 4558s would it be worth my time to go thru and replace the 60 or so chips with the 5532s and what maker of chip should I look for. Also is the 2086DD and OK chip... it looks like a low noise and high slew rate amp, or is there a better solution to that, there are about 30 of those.
Am I going to be wasting my time with this project and only see minmal returns or do you guys and gals think it could be worth doing this. It would be a bit of work to change all of the 4558s but I think I could make it thru that...but much more than that... like a new power supply or any too much cap replacement of circuit reconfig is going to be a bit much.
I am looking to you hardcore highend DIYers for some direction...
I also have some pics pf this thing taken apart that if anyone is interested in will pos. and if I go ahead with mods recommended I will try to document the results and procedure.
Thanks
Larry
