The audi probably used a small vacuum designed for HA’s. I know that is what my audi used when I had a similar problem. There is one I read about on the forum called a “Jodi Vac”. Also someone else on the forum apparently made their own from a hand held car vacuum. I did a search on Jodi Vac and there are a number of places to purchase them online. Good luck.
Freq L R
0250 25 20
0500 25 30
0750 45 45
1000 55 30
1500 40 50
2000 40 30
3000 60 45
4000 70 60
6000 60 65