Focusrite Saffire Pro 40 re-cap

[Khron]

Re: Focusrite Saffire Pro 40 re-cap

The recap was mostly for reliability reasons, or at the very least, for "peace of mind". And to be totally honest, i'm reasonably sure my not-that-great room swamped any potentially audible differences anyway

The power supply ought to have at least SOME headroom, i'd reckon. Although, if you wanted to be extra-safe, you might want to consider sticking some heatsinks on the voltage regulators (although those nylock nuts won't be fun to undo).

One other thing to consider might be to perhaps alter the voltages for the analog rails. Stock, they're +/-6.9v due to the NJM2122's which i assume do the heavy lifting, gain-wise. If you're planning to replace those too, increasing the voltages might be an option, which would lessen the voltage drop across the regulators.

I can't be bothered doing all the math, but you could get close to evening out the extra dissipation due to the higher-current opamps

[12Bass]

Re: Focusrite Saffire Pro 40 re-cap

Hey Khron,

Here's another source on op amp performance which might be of interest: http://www.sg-acoustics.ch/analogue_audio/ic_opamps/

I find myself a generally skeptical and scientifically-minded person. However, there are times when I think certain people take such an approach too far, such that they are unnecessarily cynical and dismissive. Not all aspects of component performance are easily measured and some people seem eager to dismiss audible differences as pseudoscience when it may be simply that such differences have yet to be reliably quantified through measurements. I have compared the sound of a large number of op amps and have been able to reliably tell the difference between them and I'd be happy to undergo an ABX test.

Further, I am of the view that if I am going to take the risk of desoldering and installing new SMD op amps that it makes sense to use the best performing replacements available. I know from previous experience that the NJM2068 would not fit that criterion. Also, I generally add local supply bypassing when installing high performance op amps and avoid those which are known to be unstable at low gain. Hopefully the Pro 40's power supply has sufficient current capacity to reliably power better performing op amps (high performance devices tend to draw more quiescent current).

I'm curious if you changed the capacitors in your audio interfaces mostly for reliability reasons or if it was for sonic reasons? Did you notice any difference in the sound after the re-cap?

[Khron]

Re: Focusrite Saffire Pro 40 re-cap

No, i haven't. I actually sold off the 40 this summer, to raise funds for a MOTU 896mk3 Which i promptly re-capped as well - i've got a thread documenting that too, here

With higher-performance opamps, you should be a bit careful, though. I don't exactly recall off the top of my head, but the opamps may or may not have small (pF-range) caps in parallel with the feedback resistors. If you use faster (greater GBW) opamps, you run the risk of potentially making some of them oscillate. Plus, some opamps are stable only for gains of 5 or more (OPA637 comes to mind).

That, and http://nwavguy.blogspot.fi/2011/08/o...ths-facts.html plus http://nwavguy.blogspot.fi/2011/08/o...surements.html

If you ask me, even "just" NJM2068's might be an improvement over the stock 4565's.

The safest way to determine which opamps do what would be to "beep out" the i/o pins of the codecs, and the associated opamps. Although, judging by some of the traces i can see in the photo of the mainboard, in the first post, i *think* the left-most column of 4 opamps might be the outputs. See the pairs of traces coming out of each one, and snaking their way upwards and then turning right, towards the 1/4" sockets? That would make the other 8 opamps the single-ended-to-differential converters / drivers for the ADC's.

If i were to replace opamps and such, i think i'd go the "proper" way, and use my (admittedly, uber-cheapo chinese) hot-air wand / station Some Al-foil-tape to shield the caps and connectors around, and a nice long but fine-tipped pair of tweezers, a bunch of flux, and that should do it

[12Bass]

Re: Focusrite Saffire Pro 40 re-cap

Replacing ALL the opamps with 4562's will be pricey, to say the least Not to mention that i'm quite sure it'll be far beyond the "point of diminishing returns" As i've mentioned on the first page, i've quite got my mind set on (someday) replacing all the opamps with NJM2068's - cheap and really low-noise

Hey Khron,

Thanks for creating this thread. Did you ever get around to replacing the op amps on your Pro 40?

I have a used Pro 40 that I would like to modify by replacing/upgrading bypass capacitors as well as op amps. Some years ago I modified my Echo Gina 24 sound card and measured the results with RMAA using analog loopback testing. RMAA showed that both IMD and THD were significantly lower using the LM4562 compared with the original JRC2068 op amps. The sound was also noticeably improved, IMO - clearer, less "hazy". I've made before/after recordings and measurements on a variety of modified units, showing undeniable evidence of improvement.

Will have to do a bit of research on which op amps to use as some higher performance models have come out since the LM4562. At present, my Gina 24 has a pair of OP211s on the main output. However I've found that I prefer the sound of the ADA4627-1. OPA1642 provides a nice upgrade for the TL072 used in the instrument input section.

The Pro 40 certainly has a lot of op amps! I'd like to upgrade all of the op amps on the inputs. However, I may only upgrade the output op amps on the main (1/2) channels, and leave the rest of the outputs with the JRCs (because I am unlikely to use the rest of the output channels). Do you know which op amps are used for inputs and which are used for the outputs on the CS4272s?

Also, do you have any specific recommendations for a desoldering tool?

Thanks!

[Closedbox]

Re: Focusrite Saffire Pro 40 re-cap

Just finished my PSU and decoupling update and tested it a acoustically treated studio surrounding.
I expected to find a subtle improvement in sound, but man this is HUGE!

Pls can i get details on ur power supply upgrade for the focusrite pro 40

[ico]

Re: Focusrite Saffire Pro 40 re-cap

yep.... not elegant and sadly this is the soldier way of desoldering sdm....

anyone has an idea about the frequency value of the quartz?
thanks!

[Khron]

Re: Focusrite Saffire Pro 40 re-cap

Yes, that's one way to remove SMD chips, with two caveats

1) That assumes, "by default", that you don't plan on re-purposing the stock opamps, and

2) You need to be REALLY careful not to slice through whatever traces might be running to / from / under those pins.

[ico]

Re: Focusrite Saffire Pro 40 re-cap

i found this thread because i plan to mod my saffire 56 too... and i got a lot of hints! thanks!
i already had opened it and bypassed mic input caps with film... but i am currently using the interface and cannot tear it apart for a while.... so it was nice to know what opamps are inside!

i wanted to ask if someone noted what is the frequency of the crystal oscillator... i had plans to upgrade the clock reference too...

if it can help others... i have found a fast but clean and effective way of removing smd opamps without a heat station.. i just use a sharp knife to cut the legs... then remoove each leg with a simple swipe with the tip of ordinary solder station...

[Khron]

Re: Focusrite Saffire Pro 40 re-cap

Hint: yes, a hot-air station is quite mandatory to be able to get surface-mount IC's off boards, but soldering them back on is a breeze with a half-decent temperature-controlled soldering iron

Just try to put some Kapton or aluminium tape, for heat-shielding, on the components around the chip you're trying to get off the board. Electrolytic caps and plastic connectors, i assure you, do NOT like the 300C+ temperatures needed for unsoldering SMD's

[jayache80]

Re: Focusrite Saffire Pro 40 re-cap

Hi ludwigvanlee,

I wanted to say that I'm in a similar boat. I have experience soldering and building stuff out, however I've never been happy with my repair work, often burning PCBs or melting insulation... What I'm going to do is buy a hot air rework station first thing, and practice on electronics that I don't care about- taking ICs off and putting on new ones. Once I feel comfortable, I'll dig into the Saffire Pro40. My channel 8 mysteriously stopped working after feeding it some pretty hot audio (0dbFS and up) and that's how I found this thread. I don't believe it should've blown so easily, but alas it did and I think I'll just replace the ICs on that channel and have an "upgraded" channel. If I like the mod, I can do more channels!

[ludwigvanlee]

Re: Focusrite Saffire Pro 40 re-cap

I read through what you guys did, woah.. awesome!

I'm quite the noob but I ever since a few months ago when I heard about modding, I became really interested in it though I do not have a background in it.

My question would this be easy to learn to do? I myself do not have experiencing modding audio equipment but I know someone who has experience building and fixing audio gear (though mostly inexpensive). What I was thinking was buying the materials you guys listed here then having my friend help me with it.

Would you guys recommend that?

[Khron]

Re: Focusrite Saffire Pro 40 re-cap

Getting the power supply working again definitely WILL improve your 40 Not 10000% sure about the rest, though - i did it more as a "peace of mind"-project. Although i do still have replacement opamps in stock...

[hardsmoker]

Re: Focusrite Saffire Pro 40 re-cap

All right, thanks so much for your information. I hope it will help me in improving my focusrite Saffire Pro 40. Good luck to you Khron666 \m/

[Khron]

Re: Focusrite Saffire Pro 40 re-cap

Well, as you can read in the initial post, the stock FET was a FairchildSemi FQPF8N60C. Characteristics you'll want to care about if you need to replace it with a different part number, would be:

Vdss = 600v or more
Id = 7A or more
Qg = 40nC or less
or
Ciss = 1200pF or less

[hardsmoker]

Re: Focusrite Saffire Pro 40 re-cap

And what exactly is that problem?

the problem is my technician wanted me to buy MOSFETs, but the type of the mosfet that I do not know. at least I could know the type so that I can buy at my local store. thanks for the reply Khron666

[Khron]

Re: Focusrite Saffire Pro 40 re-cap

And what exactly is that problem?

[hardsmoker]

Re: Focusrite Saffire Pro 40 re-cap

hi i have a problem with my FOCUSRITE Saffire Pro 40, the technician said that the problem is in the power supply, can you please help me to get the original schematic that contain parts of the power supply? thank you

[Khron]

Re: Focusrite Saffire Pro 40 re-cap

The heatsink's not connected to anything (else), so there's not much to tune with it. If anything needed adjustment, that would be done in the passive components surrounding the PWM controller chip

Actually, i'm reasonably sure the power supply works fine even as it is, with the heatsink "in the air". But, as before, i stand to be corrected

[surrealisticdukes]

Re: Focusrite Saffire Pro 40 re-cap

Yeah the solder tickenend trace goes to the filter cap. If it was just a "0" jumper for layout reasons, it would actually connect the heatsink to ground, which makes sense. I also was thinking it might have been some sort of fusible smd.

But i'm anxious to solder some jumper wire instead, maybe it still was some Resistor, probably fine tuned to prevent some stability problems or something.

I hope somebody can check the value for me when they recap their SMPS. Would be very much appreciated.

[Khron]

Re: Focusrite Saffire Pro 40 re-cap

Hmmm... From what i can tell, there's a reasonable chance that R37 was just a "0" jumper.

The FET is in an isolated TO220 package, and that solder-tickened trace is going to the negative leg of the bulk filter cap, right? The trace going to the FET gate goes under R37, and those 3R3 and 1R0 form the current-sense resistor (from the FET source to the negative leg of the bulk filter cap). So it wouldn't make much sense if R37 had some (greater) value. Most likely it's just employing the heatsink as a small EMI-shield of some sort, i'd reckon.

Although i AM open to corrections from more knowledgeable types