Comparison between Babyface and TT Design PSUs for SE/30?

[pax]

Has anyone done a comparison between the Babyface and TT Design PSUs for SE/30? I’m looking to swap out an original PSU.

• https://www.tindie.com/products/baby_face_electronics/macintosh-se30-universal-psu-replacement/
• https://www.tindie.com/products/ttdesign/macintosh-se30-se-assembled-power-supply-board/
• https://www.tindie.com/products/ttdesign/4xdc-apple-macintosh-se30-se-power-supply-psu/

I’m aware of several comparisons between the Babyface PSU and original PSUs.

 

[JDW]

I have not. I have only reviewed the BabyFace PSU. I believe that TT Design version came out AFTER the BabyFace was released. Not sure who "borrowed" whose idea, but they both use the same "modular" voltage conversion units. And in my testing, I can tell you that you will get loss through the Mac's wiring, even with thick 16AWG cable upgrades. The stock SONY PSU has a POT you can crank up to yield a voltage higher than 5.0v. That's really nice because you can mostly eliminate your cable voltage drops.

So while the Meanwell modules used on the BabyFace and TT Design PSUs are better tech overall than the old SONY or ASTEC PSUs in vintage Macs, they all have the same issue — voltage is fixed and you cannot increase it to offset resistive losses in the Mac's cabling and in the motherboard.

I don't say this to bash anyone or the tech. It's just a fact.

The practical implication is that if you have a stock SE/30 or SE with no PDS card or motherboard upgrades (other than RAM), and especially if you have upgraded your main wiring harness with 16AWG wires (which EVERYONE should do), you have no worries about any meaningful voltage drops.

Voltage drops become an issue when you stack lots of power hungry upgrade onto the machine. And while all the voltage rails will experience some resistive losses in cabling, the only one that matters is the 5-volt rail. If you go lower than about 4.65V (as measured at the external floppy drive connector on the motherboard, you at risk of freezes, crashes or mysterious lockups. You need about 4.75V on at the low end, really. But 4.90v and higher is best.

I know this does NOT answer your questions, and honestly, I'd love to hear a detailed comparison of the two products as well, but overall, the limitations of the MEANWELL modules in a vintage SE or SE/30 are just as I described.

 

[pax]

Thanks @JDW. Your excellent review of the Babyface PSU is one of the once I’ve looked at. I have also upgraded my main wiring harness and can attest it’s a game changer, highly recommended.

I have noted the following differences in PSU specs between these options.

Voltage Rail	Original Spec	Babyface	TT Design Standard	TT Design 4XDC
+5V	6A	6A	8A	10A
+12V (Disk)	2.1A	2.1A	5A	2.5A
+12V (Sweep)	1.25A	1.5A	5A	1.8A
-12V	0.5A	0.5A	0.85A	0.85A

Furthermore, the Babyface and the TT Design Standard have a shared +12V supply for both Disk and Sweep, while the original and the TT Design 4XDC have two separate +12V supplies (quoted as helpful to ”minimize cross-talk between the Disk and Sweep rails” resulting in flickering displays under heavy load).

Finally, the TT Design Standard (starting from Version 0.6) and TT Design 4XDC have a 4-pin 5V AUX connector to allow for using a cable to bypass the analog board’s 5V distribution and connect directly to the logic board (when using 040 upgrades, internal grayscale, etc.).

 

[JDW]

Thank you for the detailed info!

I assume you don't have any of those PSUs yet and are merely mulling which one to buy?

As I thought, even the top end PSU costing $170 cannot get around resistivity losses due to it outputting close to 5V. That is shown by the voltage measurements presented in the documentation:

GitHub - tt-design-studio/psu-mac-se-4xdc

Contribute to tt-design-studio/psu-mac-se-4xdc development by creating an account on GitHub.

github.com

With that said, 4.90V under such a heavy load on the 5V rail is perfectly acceptable. Whether $170 for that PSU is acceptable or not is another matter.

 

[pax]

I assume you don't have any of those PSUs yet and are merely mulling which one to buy?

That’s right. I do have another fully functional recapped PSU also, but I’m intrigued by these replacement products for my next build.

Thanks for digging into the documentation!

 

[JDW]

Even the lower cost PSU from TT shows the same 5V rail voltages, which is what I would expect...

GitHub - tt-design-studio/psu-mac-se: Apple Macintosh SE/30 and SE DIY replacement power supply board (PSU)

Apple Macintosh SE/30 and SE DIY replacement power supply board (PSU) - tt-design-studio/psu-mac-se

github.com

I'm therefore not seeing the practical benefit of the $170 version over the $129 one.

 

[scj312]

I'm therefore not seeing the practical benefit of the $170 version over the $129 one.

It seems to me like the 4XDC version would be beneficial only for systems like yours where you experienced 12V noise issues with the Micron Xceed card installed.

 

[JDW]

It seems to me like the 4XDC version would be beneficial only for systems like yours where you experienced 12V noise issues with the Micron Xceed card installed.

But is that worth $170?
Especially when I don't have noise issues with my stock SONY PSUs or my SEASONIC?
In my opinion, it is not worth $170.

Sure, it's nice to have a modern, well made power supply. But if you watch my SEASONIC video from 2018, I was able to get such a PSU and substantially lower price. Not only that, but I had less of a voltage drop with the SEASONIC versus the BABY FACE, for reasons I mentioned in my earlier posts in this thread. More specifically, because the NO LOAD voltage of the SEASONIC is 5.14V versus the low 5.05V for the Meanwell 5V module! You can see that and so much more in the Google Spreadsheet I made for my BABY FACE PSU review video here:

SE/30 Power Measurements (JDW-2024)

docs.google.com

NOTE: There are 3 tabbed sheets in that spreadsheet, accessible via the tabs shown at bottom.

Am I complaining about there being modern PSUs other than the SEASONIC? No! I'm not trying to tear anyone down either. These are just FACTS. Sometimes, the facts feel cold, but they are a reality worthy of consideration.

BOTTOM LINE: How low will YOUR 5v rail go on YOUR preferred PSU, with YOUR upgrades installed?

If the answer is "lower than 4.65V," even for brief periods of time, you need something else. Seems like the Meanwell PSUs can do the job, especially when matched with a 16AWG harness upgrade (to reduce resistive voltage drops), but in my case, I had noise issues with the BABY FACE, and although there is "speculation" a $170 version PSU would resolve it, I personally am unwilling to spend $170 in the "hope" that it would. $170 (shipping extra) is a lot of money for an SE or SE/30 PSU. Wow. It's a lot!