The classical vocal technique has one huge component. Without it you will not be able to make the classical sound. Classical singing is all about singing with a forward tilted larynx. The level of tilt determins weather the voice sounds like a renaissance voice with little vibrato or opera with a lot of vibrato.
A good way to train this tilted position is making the sound of a crying puppy. When you feel your throat with your hand you can feel the larynx tilting forward. Try to sing in this position and maintain the tilted position. Put your fingers on your larynx (below your jaw in your neck) and feel what happens if you speak: “How are you”. Now speak this sentence again like you are about to burst into tears. You will feel that the front of the larynx now tilts forward. It may feel like the front drops a little bit.
The position of your head can help. Watch the video.
When you’re having difficulties tilting there might be too much tension in your lower jaw, your tongue and/or the root of your tongue. Release all tension, act like an idiot and then try again! Another way to get to the classical sound is to imitate opera singers. Watch Marc Martel’s video as he explains how he found his classical voice without the help of a voice teacher.
The german ö-sound will help you to tilt your larynx, as long as you pronounce the vowel with a relaxed lower jaw.There are a lot of videos about vibrato on Youtube. Unfortunately many are rubbish…