tar/gzip excluding certain files

I have a directory with many sub-directories. In some of those sub-directories I have files with `*.asc` extension and some with `*.xdr`. I want to create a SINGLE tarball/gzip file which maintains the directory structure but excludes all files with the `*.xdr` extension. How can I do this? I did something like `find . -depth -name *.asc -exec gzip -r9 {} +` but this gzips every `*.asc` file individually which is not what I want to do.