Dahlquist DQ-10 - did they use Advent woofers?

I don't know who actually manufactured the woofer but yes, it is the same as the large Advent woofer. DQ-10s below serial number 400 used a 12" CTS woofer. BTW, kits to replace your foam surrounds are available on ebay and it's a relatively easy project.

it is the same woofer used in the Large Advent that Kloss designed. As above, it is probably the surround. However, search around and you may be able to find a replacement woofer. I've seen a few.

Yes, it's a Advent woofer. These guys will have everything you'll need, http://www.regnar.com/

I had a couple of Advents when they first came out. As I remember, one of its features was that the woofer was a 10" cone built on a standard 12" driver frame, so as to leave more room for a compliant suspension. A clever low cost production strategy.

I thought that the Advents sounded good, particularly as a "stacked" pair, which enjoyed a brief period of high end hype. However, I found the midrange, particularly vocals, to be lacking in comparison with the similar sized KLH5 and the KLH 12 (same drivers) which were three-way designs.

As J. Peter Moncrieff stated: "No midrange driver, no midrange".