M-Audio Octane Mod 412 op amp+++

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electrorocket

Member
Joined
Jul 7, 2006
Messages
16
Location
Brooklyn, NY
Greetings! This is my first post. I signed up because I was having a problem with a mic I was working on, but I'll get to that in another post. First off, I'll admit I'm no guru like the lots of you, but I've done a bit of modding and fixing.

So on with it then, the M-Audio Octane. I like this preamp. Pretty great for the price and the features. Just figured I could get some more out of it! So I just cracked this thing open to see if I could supe it up any. My first stumbling block is the opamps. Well, they're all soldered on, but that won't be a pain really. All the other chips are SMD though! The op-amps are marked JR31AF
LF
412CN

anyone have any info on these, and if there's any suitable upgrades?

There's a couple other chips on each channel as well, but I'm not TOO interested in them, like I said they're SMD, and I'd probably ruin it! But if you're curious, since I got this open anyway, they are LM339AMs and INA163UAs. Then there's some other chips I'm really not interested in, the line in and out chips(don't use them) and the converter chips(use the adat out, but don't want to mess with that)

Then there's the power section. I mean, the thing's got an external PSU, but this seems to have some extra power things going on I'm not sure about. The PSU is 18 volts/3.5 amps. There's 2 2200uf 35v electros, 2 220uf 63v, a 47 16v and a 22 uf 16v. There are also 2 5404 silicon diodes, and 2 smaller ones. I can't quite make it out right now. The last 3 numbers are 004(4004?). I guess this might all be a part of some voltage multiplying scheme. There's also an L 7805 ACV, a 7915 ACT, L 7815 ACV. Was wondering if changing any of this might help out? I know in other PSU circuits people like to upgrade the filter caps at least(elna cerafine perhaps), and what about upgrading to zener diodes?

Oh, now back to the mic section. The ins have 22uf 63 v electrolytics on pins 2 and 3, so those are probably prime candidates for upgrades as well. Then there's some of the little yellow rectangular capacitorslabeled 470nJ 63. And they have a little slanted 'T' at the beginning. They seem to be going to the opamp. The opamps appear to be 2 channel. On that note, I'll try and use every other channel, if I can, to avoid crosstalk. Not that I've had any problems with that, that I've noticed.

And, just to be a completist again, the 2 phantom power switches each have C3071 3K transistors and 4004 silicon diodes, and 47uf 63v electrolytics. And the DIs have 220uf 10v and 47uf 16v caps.

Wow. Well, I know that this post got kind of tedious, so basically the big question is about the 412 opamps, those yellow caps, and the PSU.

Thanks!
 
i´ve read about the phantom power producing noise when feeding mics that need more current. have´nt experienced this myself though. i mostly use it as a converter.
 
I've once opened an M-Audio Octane. I remember it was full of NE5532s (SMD), which still is a good opamp if you ask me. If that's still the case, I'd say don't mess with it. Fine as is.

I don't remember the LF412. That's a low offset opamp that may be used as a servo for the INA163's output. Or maybe to correct the DC offset at the gain setting pot. If that's the case, don't mess with it.

The Octane is a fine piece of gear for the price, I doubt that you could improve anything at any reasonable expense.
 

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