vintage Foster 10F3 Alnico magnet 4\" full-range driver, Japan c.1967—excellent For Sale -

Offered for your consideration is one (1) vintage Foster 10F3 Alnico magnet 4 inch full-range driver, made in Japan c.1967. As you probably know, Foster (later branded as Fostex) was a notable supplier to the speaker industry and their full-range units have long been favorites of speaker-building hobbyists. So, please have a look at the large photos and read the remaining description to decide if this venerable driver is suitable for your needs.

This Foster 10F3 is in clean, excellent overall condition. The sturdy paper cone is structurally flawless, just a tiny bit of age staining, and the voice coil dustcap is perfect as well. Plus the inverted surround is permanent, textile factory coated for added durability, instead of the fragile foam that would soon come into widespread use. And, the anodized steel basket is in great shape with no dents, scratches, or noteworthy oxidation. Lastly, the +/- terminals measure the standard .205”, are marked for polarity, and I de-soldered them for the new owner’s convenience.

It’s been fully tested and sounds remarkable with fast, detailed midrange, sparkly highs exceeding the audibility threshold, and decent low end for the platform size. Plus, it has the Alnico magnet warmth of tone sought after by audiophiles and others “in the know”. And, DC resistance tested at 7.9Ω consistent with a nominal 8 ohm driver rating. Lastly, the basket measures 4⅛” across (4 15/16” at corners), it stands 2 13/16” tall, and the mounting holes are spaced 3¼” adjacent / 4 9/16” diagonal apart, c-t-c.

This is a great find if you need this driver as a replacement for your Realistic Solo 103 or other vintage speakers that originally came with one. Or, it’d make a great foundation for a single-driver speaker project for that modest-power mono tube amp you’re looking to put into action! So, as pictured and described, this great condition, perfect sounding Foster 10F3 4” full-range driver is offered at a competitive price.

Terms of Sale:

I encourage interested parties to e-mail any questions they may have about this listing before committing to purchase. Payment is due at checkout by PayPal. U.S. mailing addresses will pay $9.95 for very carefully packed shipping by U.S. Postal Service with tracking and delivery confirmation. International purchases accepted only from those who are able to pay with PayPal, including shipping by USPS Global Priority Air Mail—fast but costly—no exceptions. Thanks for looking!