Apache2 virtual host config:
# svn.three-dimensional.net
<VirtualHost 82.103.138.183:443>
        SSLEngine On
        SSLCertificateFile /etc/ssl/certificates/apache2_default.pem
        ServerName svn.three-dimensional.net
        CustomLog /var/log/apache2/svn.three-dimensional.net.log combined
        <Location />
                Order allow,deny
                Allow from all
                DAV svn
                SVNParentPath /home/subversion
                AuthzSVNAccessFile /etc/subversion/public-svn-authzfile
                Satisfy Any
                Require valid-user
                AuthType Basic
                AuthName "three-dimensional.net Subversion Repository"
                AuthUserFile /etc/subversion/passwd
        </Location>
</VirtualHost>

apache2 loaded modules:
threed002:~# ls /etc/apache2/mods-enabled/
actions.load     authn_file.load       authz_host.load  cache.load  cgid.load     dav_svn.load  env.load      headers.load    mem_cache.load   negotiation.load  setenvif.load  status.load
alias.load       authz_default.load    authz_user.load  cgi.load    dav.load      dir.conf      fastcgi.conf  include.load    mime.load        perl.load         ssl.conf       suexec.load
auth_basic.load  authz_groupfile.load  autoindex.load   cgid.conf   dav_svn.conf  dir.load      fastcgi.load  mem_cache.conf  mod_python.load  rewrite.load      ssl.load
threed002:~# 

dav_svn.conf is a file with the default configuration all commented out

content of /etc/subversion/public-svn-authzfile:
threed002:~# cat /etc/subversion/public-svn-authzfile 
[groups]
owner = michiel
mvblog = michiel, userx, usery
mvpastebin = michiel
pure = michiel
threed = michiel, userx, usery
dnsprov = michiel
ambernet = userz, michiel
tracbot = michiel

[/]
@owner = rw
* = r

[mvblog:/]
@mvblog = rw
* = r

[pureuseradmin:/]
@pure = rw
* = r

[threed_docs:/]
@threed = rw
* =

[michiel:/]
michiel = rw
* =

[dnsprovisioner:/]
@dnsprov = rw
* = r

[ambernet:/]
@ambernet = rw
* = r

[mvpastebin:/]
@mvpastebin = rw
* = r

[tracbot:/]
@tracbot = rw
* = r
threed002:~#