Write an instrumental ad bed prompt for Lyria 3.5 on Sume Music

State "instrumental, no vocals" in the prompt, then give tempo, instruments, mood and how the track should end. Sume Music takes a prompt of 1 to 5,000 characters, and each generation is a flat $0.125 on Lyria 3.5.

There is no duration field and no negative prompt, so everything you want, including the absence of a singer, has to be in the text.

What the route accepts

Music 1.0 and the Music Router share one fixed price per generation.

A prompt pattern

Put the constraints first and keep it to what a producer would say.

Instrumental, no vocals, no spoken words.
Upbeat acoustic-pop bed for a 15-second product ad.
Tempo 110 BPM, clean guitar and light percussion, soft synth pad.
Starts with a short intro, builds, then ends on a clear final chord.
Leaves space in the mid frequencies for a voiceover.

Why each line is there

None of this is a guarantee, since the model decides, but each line removes a common surprise.

• Instrumental first: the only control you have over vocals is the prompt.
• Tempo: gives you a grid, so cuts can land on beats in the edit.
• Ending instruction: because you cannot set a length, a stated ending gives you something to trim to.
• Space for voiceover: pairs with the ducking option on a Timeline 1.0 soundtrack, which takes duck_db from 0 to 20.

Iterating without waste

Change one thing per try: the instruments, then the tempo, then the ending. Save each prompt next to the file it produced. At $0.125 per generation, six careful tries cost 75 cents, which is cheaper than six vague tries that teach you nothing.

Fit it to the cut

Because length is not a setting, plan to trim. Sume's timeline audio route can cut a range out of a track or join parts, and a Timeline 1.0 soundtrack supports fade_out_seconds up to 10, so a bed that runs long can fade under the last shot. If you regenerate, each try is another $0.125, so keep notes on which prompt produced the take you kept.