Profire 2626 Modding

We were asked for this instruction for pretty long time, and every time someone
asked us we wrote complete explanations (but without pics) in private messages.
Finally, this manual will be available for public access.

This is not a manual for newbies, nor this is a detailed instructions,
it is just a roadmap for those who skilled in soldering and can read schematics from the board. 

Think of this instruction as of an example of what you can do, but you can do more!™


It is not a secret, that excellent audio interface excels a good ones mainly in analogue circuits.
There are too much compromises made in mid-priced soundcards: cheap, bad sounding opamps,
cheap caps of small values and low operating temperature limits, and so on.

Definitely, any AD-DA interface will benefit from good designed discrete-based preamp, for example,
but this is completely different topic. We'll limit our mission to changing bad sounding opamps
to good or clean sounding ones — you should choose them depending on your own taste, and changing
electrolytic caps for more appropriate ones.

In our case we used a NE5532A opamps (yes, i like their sound), Panasonic FM-series caps
in audio paths (bypassed with film caps on a back side of a board) and Jamicon caps in power decoupling.
You can use whatever you want (well, almost everything). You can follow opamps replacement
suggestions by Jim Williams (start search here), this is not a cheap way, but you'll get hi-end performance.

So, you'll need:

• About 36 new opamps (if you not swapping those in headphone amps)
• 16 caps for phantom voltage blocking on inputs
• Caps for DC blocking/decoupling in buffer stages/preamps — cannot count exactly, DIY, please
• Caps for opamps local power decoupling
• Big caps for power supply decoupling

Here we go:

Unsolder 7 wide ribbon cables (they're connecting preamps and sockets on back).
Remove all caps (you should remember/mark their values and types).
Remove all opamps (be careful — do not overheat board or unsolder small SMD components).


This is what you'll get after all desoldering. Recycle properly or reuse those.


This THAT 1510 mic preamps should stay, they're pretty clean and nice. Think of them as of improved famous BB INA 217.


New caps are larger than old ones, take care of placing them properly.


Those caps are not only larger, they have thickier legs, so you should solder them like SMD, not through-hole. Take care of alignment.


Here you can see solder drops for such preudo-SMD caps mounting.
Sure, you need to solder opamps before caps, at least before those caps placed around them.


Here's what you'll get when you'll finish all replacements:


Nice new opamps. Yes, i prefer 5532A.


A complete picture. A helluwalot of cans.

Some further modding options: phantom powering switches for every channel.
Pretty simple but very useful, although you should cut new holes in front panel.

One DPDT switch and one LED per channel. Just cut fantom traces from mic inputs,
replacing them with wires from switches, and throw out existing phantom enabling buttons.


Here's new power cable connector.
We did a completely new PSU for 2626, so this DE9 socket is for bipolar 15V for opamps, 5V for digitalia and separate 48V for phantom.
There's also low-voltage power switch, which remotely turn on and off PSU mains via relay.


Low-speed cooler, placed diagonally. All those 5532s getting pretty hot on 15V rails, so we decided to put a fan in unit.
You can use small cooler, made for 1RU devices.
Also you can see local power decoupling caps — those Jamicons in yellow insulating tape.
...Such a mess when it is not finished!

New power supply unit:
— 2x15V for opamps power rails, dedicated transformer and LM317/337 stabilizer;
— 5V for digital ICs, dedicated transformer and LM317 stabilizer;
— 48V phantom power, dedicated transformer and LM317 stabilizer.
Yes, 3 separate transformers, like all those hi-end folks like.


PSU with massive cooling system: two radiators for PC processors on LM317/337, one low-speed CPU fan.
All assembled in ordinary PC SMPS box.

Kind of the end of instruction.
It is up to your decision what components you'll mod in your particular case.

BTW, you can modify exactly same way any interface with good digital section, like
those TC Applied' DICE-II based ones — M-Audio Profire series, Presonus and Focusrite firewire devices.
Avid M-Box Pro and TC Konnect already have pretty nice opamps, but we think there's
always a place for small improvement — it is all up to your taste.

As for real improvements in performance: you may believe it or not, but 10 out of 10 people,
both sound engineers and just experienced listeners said this unit sounds much better than RME FF-800
and FF-400 units in direct blind comparison. Much cleaner highs, more "air", less cluttered mids,
much more defined and solid lows, to name a few of improvements — just as we hoped it should improve with this mod,
but it is much more than just words to hear.

Feel free to ask questions.