Artifact when printing from a PDF with transparent object

[Jennifer23339790d42j]

I have an AI file (attached) that includes an object set at 50% transparency. When I save the file as a PDF and print from the PDF, a darker rectangle prints inside the area of the bounding box of the transparent object:

We use PDF XChange Editor as our PDF software. The box doesn't show up in the PDF on my screen, only in print:

It prints fine without the artifact from AI, so I think it must be something to do with how I'm exporting it to PDF. I've tried multiple export settings, but here's what I have currently which is not working: 

Another weird part of this puzzle is that this problem only began when we recently upgraded our very old printer. We didn't have this problem when printing this PDF file on our old printer. 

Other people on my team need to be able to print this doc, and not all of them have access to AI, so I really need to figure out what's going on with the PDF. 

Appreciate the help!

[Monika Gause]

Please check out https://creativepro.com/eliminating-ydb-yucky-discolored-box-syndrome/

[Jennifer23339790d42j]

Thank you! Is there a way to essentially apply the transparency flattener the instructions you linked say to create while saving as a PDF? The document is fine when I print it through Illustrator, but when I save it as a PDF and print it through our PDF software, that's when the artifact shows up. Other people on our team who don't have access to Illustrator need to be able to print this document, so I'm hoping to find a way to fix the PDF. 

[Monika Gause]

You can create a flattened PDF.

Save is as a PDF/X-1 and then use the settings mentioned in the article for transparency flattening in the PDF settings.

[Brad @ Roaring Mouse]

What's your new printer? (brand/model). (also, what was your old one?)

[Jennifer23339790d42j]

The new printer is a Toshiba e-Studio 3525, and the old one was a Konica Minolta C364. Thanks!

[Brad @ Roaring Mouse]

Sorry for the late reply:

Part of the issue is that you are using spot colors that are maintained in the PDF, but are being converted to cmyk in two different ways, and not equally, hence a color difference. 1: the object you have applied the transparency to is being instructed to convert to cmyk according to the transparency space/color management settings set in your Illustrator file (which appears to be US Web Coated). Unfortunately, 2. the other objects are being sent in the PDF to your printer driver as spot colors, but with there is no destination profile defined, so the printer driver is using its own profile (whatever that is) to convert to cmyk. (incidentally, Web Coated is an older profile so tends to look darker than modern profiles, especially in digital).

If you have No Conversion specified in your PDF Export (which is default for PDF/X-4:2008), try change it to Convert to Destination (Preserve Numbers) and see if that solves your issue.

I looked at your Toshiba's specs, and although it can come with a Postscript option, it might not be what you have, in which case your color data is being sent as RGB, which very likely cause the difference.

The other solution is to change your color swatches from Spot to Process in your files so everything is treated equally.