OPA2604 a good choice to replace TL072's in soundcraft 200b?

Greetings all,

Great site - one of my friends who is building projects pointed me over here. The Meta pages have been great !

Im just dipping my toes in all this stuff. This is my first post and will be my first audio project.

Ive just picked up a Soundcraft 200B console with 24 input modules.

Im looking to do a recap and change the opamps (on a couple of channels at first).

As per title, is the 2604 a good choice here ?
What are the alternatives?

I understand NE5532's are a cleaner alternative, but draw more power?

The console has the original PSU, and has 24 input modules.
Any idea whether this original PSU will be sufficient?

What about recapping - where should I be looking for info on appropriate replacements?

Any advice greatly appreciated...

Many thanks !

Ben

When I had a 200B I put OP275GPs in the inputs and OPA2604s in the master section. That was the combination that sounded best to me at the time. Try putting sockets in a couple of channels and check out all the options and see which you prefer. I beefed up the power supply, and that might be a good idea under any circumstances. I also had Eddie Ciletti do his grounding mod and replace the 2-track bus insert drivers and and mix amps with API 325 cards. It was a pretty sweet sounding console.

[quote author="jrmintz"]I beefed up the power supply, and that might be a good idea under any circumstances.[/quote]

Thanks Seth

Can you elaborate?
Did you replace the PSU ?

No, I replaced the filter caps with larger ones and bypassed them with polypropylenes. I also replaced the rectifier bridge with one made out of HEXFRED high-speed diodes. Whether or not that made a real difference is hard to know and there are plenty of folks whom I greatly respect that will say it's audiophoolery. I didn't make careful before-and-after comparisons at the time, unfortunately. I think adding a quiet fan couldn't hurt. The net effect of all the changes was that the console sounded very, very good.

howdy all. had a similar issue a while back with a TAC matchless desk channel. it didnt sound very transparent at all. quite lifeless. I tried with success a few OPA2134PA from RS components and the difference was instant. brighter. better reality and life. same frequency response.
i got all excited at the prospect of removing all the output coupling caps. so i took those suckers out. ahhh... now we are getting somewhere. i can now say that the channel is as good as it can be. sounds full and strong. eq is sweeter. The matchless has chip muting ic that i bypassed too. much further improvement.

Thanks for the info Eka

Hey EKADEK, did you have any problems with the extra current draw on the OPA's or was this just a single channel, not the whole board.

I'd be interested in any more details you have on the mods you made.

i only have one channel plus a couple of stereo return chans from a tac desk so current draw isnt a problem. The other thing i did to this channel was bypass the front end line de-balancing amp and remove a couple of ne5532 chips that were'nt doing anything. Ive yet to do the stereo channels but i guess they will get the same treatment. my studio is made up of many and diverse single and stereo items all patched thru a discrete mixing board.( sorry my site is down at moment)
I imagine that one would have to be careful about power supply capabilities. I will measure the difference (i have one other tac eq chan that ive kept unmod-ded thus far.( cant do this for 1 week tho as im taking my little kids away on holiday.) HAPPY NUDE EAR all.

what you need to do is count the number of 5532s and tl072s etc. and add up a rough current draw for the board using the datasheets for the opamps and compare that to the draw for the replacements. this should give you a rough number for increase of current draw.

I assume this is a switching PSU but I dont know. Switching PSUs are usually chosen for somewhere around 50-80% dutycycle in normal use. some are actually much heavier duty, maybe a few too small for proper use. If it's a switching PSU it's likely an off the shelf part and you should be able to find the model of the PCB and call up the maker and find out some info on it.

or..

just hook up a current meter and see for yourself.. :shock:

The OPA2604 are really, really good audio opamps. Clean and powerful. The OPA2134 is another, lower cost alternative.

jh

Thanks

Seth has been helping me with the power supply mods via PM...have yet to decide how long a life the desk will have with me, and that will influence how far to go with the mods.

Happy new year to all

I would recommend the OP270EZ in the military ceramic package.

CDIP - 8

This op amp gives incredible boost and life into the audio signal.
It is a nice replacement for NE5532's and TLO72.

the slew rate on this is slow so I think this may be a good thing .
It is a high performance op amp with very very low noise.
The largeness in sound on this opamp is simply amazing, I was stunned the first instant I ran audio thru it. very nice results. It makes the 5532 sound lifeless.

I have experimented with this one personal level and I don't recommend
anything that I have'nt tested myself. My take is ..... if it does'nt dramatically improve the audio quality its just a waste of $$ and time.


Also, regarding the power supply ......

Could you just pick up a Power One linear regulated supply that provides double the current needed and mount it in a enclosure or will you build your own power supply from parts ?

I'm currently looking to put a power supply solution together for a different soundcraft console. To allow the console to draw a little more power while either increasing headroom or lowering noise and ripple in the power supplied to the console under heavy current demands. I believe the voltage required is +/- 15vdc at 1.25 amps. I would like to at least triple that amp spec in the new supply.

My current original power supply has a strange hum/buzzing sound too, don't know what is wrong yet, has any one experienced this ? Is the power transformer going bad ? Maybe I need to measure the curreent draw, any suggestions ?

As far as capping goes, I'm tring to find suitable replacements that are refered to as "coupling capacitors", low impedance and high frequency with temperature specs at 105 degree rating .

In the console I have been comparing different Brands like Nichicon, Sprague and Panasonic. I have also been increasing some of the capacitance values in the mic pre section to gain a thicker bottom end in the audio and cleaner high mid and highs. So far it is working , but the difference is not as dramatic as I wished for. I'm doing the same in the EQ section as well. I'm starting with caps then moving on to the opamps. And Boy this really takes alot of time. I try not to listen to long when A/B comparing because ear fatigue sets in and perception gets altered. SO I continue to experiment and compare the moded input channel to the factory original and A/B listen until I get results.