Soundcraft series 600. Next step.

Thanks to all that helped me fixing my Soundcraft Series 600.


Well, the powersupply problem is fixed. What would be the next step?

This console has not been used for a while. It's a bit noisy. Some channels sounds like a nice campfire when I put the faders at max.

Should I start with replacing all the caps?

Would a op-amp upgrade make things better?


...and also....


The hipass filter is set to 100hz. I would like it to be lower. Can I do this with simply changing the values of the resistors and caps in that filter section?



Thanks again

Richard

do those have removable channels? if so, most people tend to take a pair and do all the mods they can to them and see if it actually makes it sound better. sometimes the design is good and the parts are poor so upgrading them makes it sound great. other times the design is poor so throwing money at the channels won't do much more than just change the sound..

I would start with recapping with a good quality cap and possibly shunting them with polypro/ester and see what happens.

:thumb:

Yes - start with the electrolytics on the channels.

Click to expand...

Personally I would start with the electrolytics on the master channels, since they effect the sound of every other channel. If you do channels first then you will not get a true representation of what your changes have made if the masters are operating below par.

Thanks to all,

I had the master channel out just now and there are lots of electrolytics. 47uf/25v, 100uf/10v, 2.2uf/50v. I'll probably end up using Panasonic caps for this. Any particular type I should use?

I have to say that I'm a newbie (also norwegian :? ) and I'm not sure I understand that shunting thing? Can anyone explain?
There are lots of really small caps, 100pf and 33pf. 33pf "around" the opamps (TL072, TL071 and NE5532)

There are several places where there's a 2.2uf/50v electrolytic for "Local decouple for IC". What exactly is that?

Thanks again


Richard

The small 100pf 33pF etc caps round the op amps need to be there to stablise the op amps, which can be prone to high frequency oscillation without them.

The shunting thing is a technique whereby you put a small value (100nF maybe) caps in parallel with the electrolytics, which some people believe improves the sound.

If the system is not used for some time and it it dusty , clean the faders they are alps k type. Open them and use IPA from Contact to clean.
A lot of noise will be gone , for the masterchannel use mc33078 the sound much better and will work in the 600.

Thanks to all.

This is the perfect place to learn about this stuff. Nice to have this old Soundcraft to work on too.

More questions:




This is the first stage of the preampsection. TR1 and TR2 are 2N4403's. After that the signal goes to the first opamp (TL072). What exactly is this first dual transistor stage? Is this a gain stage or is it "something" to prepare the signal for the opamp?


C3 and C4 are 100uf/10v electrolytics. One from mic+ and one from mic-. C1 and C2 are 47uf/63v electrolytics (not in picture) They are the first thing that "happens" after the mic input. My question is: What is the function of these caps, why those values? What would happen if I put in other caps with higher or lower values?


Again, thanks to all.

Richard

those are there for impedance conversion among other things. in layman's terms, they get the signal ready for the opamp. I would change that tl072 to something like an opa2604 for starters.

those 63v caps are there to block the phantom DC from coming back into the preamp and blowing things up. I would change them to something higher like a 470/63v for reasons that you will find in other postings, so do a search. I can't make out exactly what the 10v caps do because of the cropped pic, other than they are coupling caps. they are in the audio chain so i would change them too. I suggest Nichicon HE or PW series for everything, PS and audio coupling.


:thumb:

I realize it's been a while since you posted, but I wonder what mods you ended up doing?

Just got a 16 input SC 600 that I'm gonna recap as well as try and mod. Since it's only 16 inputs I guess I can try IC's like OPA2604 which draw more current.

Anyone else here that's modded a 600 console?

600 schematics:http://www.soundcraft.co.uk/downloa...des/series_500_600/500-600_user_guide_3-4.pdf

I'm also thinking of adding an unbalanced>balanced converter to the channel line outs. Took 16 of them out from a trashed EELA Audio broadcast console.
They have a transformer labelled "818198", see image, and a TL072. Don't know if it'll be worth the hassle.
The SC internal operating level is -6dB and I don't know the EELA's internal op. level,
but I guess I might be able to change some of the resistors on the balancing boards to match the levels.
I'll try and dig out some schematics and post here.

I found a level diagram for the Eela and it seemed to have around -6dB internal operating level as well, so interfacing the line amp with the 600 console won't be a problem.
The line amps are actually about the same width as a channel strip and will fit perfectly inside the 600.
Anyways, here's the schematic if anyone's interested.

And, I'm still interested to hear from other 600 owners about other mods!