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Suno v6 sounds dull? Here is what changed and how to bring the top end back

Updated 2026-09-16

Suno shipped v6, v6-wild and v6-mini on September 9, 2026, and retired v5.5 the same week. The reaction on r/SunoAI split in two. Some people hear cleaner vocals. More people say the top end is worse, and one post put it plainly: "high end almost completely gone." Both reactions can be true at once, because v6 changed the vocal chain and the treble rolloff at the same time.

What actually changed

Suno still generates at 32 kHz internally. That part did not move. What moved is how aggressively the model rolls off the top of that range before it hands you a file. v5.5 had its own complaints about hiss, crackle and a metallic ring between 3 and 6 kHz, and some of that carries straight into v6, because the underlying cutoff behavior near 16 kHz is the same problem wearing new vocals. A few v6 exports sound duller than v5.5 at the same settings, which points to a softer, earlier rolloff rather than a cutoff that moved.

How to tell what you actually have

Put the file on a spectrum analyzer. There are two shapes to look for. A hard cliff near 16 kHz is the same cutoff v5.5 had. A gentler slope that starts closer to 10 or 12 kHz is newer, and it reads as "dull" rather than "clipped." The second shape is harder to fix with a shelf boost, because there is more missing above it, not just a sharper edge to smooth over.

What does not fix it

A high shelf above 10 kHz. It raises whatever noise survived the rolloff along with the last sliver of real signal, and on a v6 file that noise floor sits close enough to the music that the boost sounds harsh before it sounds bright.

What works

• Measure the actual rolloff shape on this file. v6 and v5.5 do not cut off at exactly the same point, and wild and mini differ again.
• Rebuild the top end from the harmonics that survived, instead of boosting a band that has nothing left in it.
• If the vocal sounds cleaner but thin, that is usually missing low-mid body, not a top-end problem. Check 250 to 400 Hz before touching anything above 10 kHz.
• De-ess first if the file still carries the 3 to 6 kHz ring from the v5.5 era. Clearing that before the rebuild keeps the rebuild from amplifying it.

Before you release it

Suno capped downloads on September 3, 2026: seven lifetime on Free, twenty a month on Pro, sixty a month on Premier. Commercial rights only come with a paid-tier download, so check your plan before you spend one on a take you might redo. Suno also announced audio watermarking and fingerprinting on August 6. Burnish does not remove or interfere with that. It measures what the analyzer finds and prints every move in dB, nothing else.

Run the free analysis on your v6 export before you decide it is unfixable. It shows the actual rolloff shape and the low-mid balance on your file, not a guess from a forum thread.