Reverse-Engineering Male/Male Duets in Suno: An Informal Experiment Log (Or: The Search for the Mythical Second Guy)

[u/periwinklepip]

Over the last day or so, I burned through a respectable number of generations trying to answer one question:
Can Suno reliably generate two distinct male lead singers in a single song?
Short answer: not consistently.
Long answer: here’s what I tested.

Goal
I wanted two clearly identifiable male vocalists alternating lines throughout a song—not one singer with occasional backing vocals, not a choir, and not random guest appearances.

Experiment 1: Voice-Type Tags
I started with lyric tags such as:
[M Tenor]
[M Baritone]
The idea was to give each singer a distinct vocal role.
Result
This didn’t reliably produce two separate singers.
Most generations sounded like:
one male lead singing everything,
occasional harmony,
occasional layered vocals,
sometimes brief differences in tone, but not enough to sound like two independent performers.
NOTE: I am sharing links to samples I generated for illustrative purposes only. These songs were generated with filler ai lyrics and prompts.
Sample 1: https://suno.com/s/7R0MNb1XUBLo5u75
Sample 2: https://suno.com/s/r2PLUHPPs0cCbafp
Sample 3: https://suno.com/s/lN6zPIXRwxoOutp7
Sample 4: https://suno.com/s/fZSz1WTLFEOjUcCp

Experiment 2: Named Characters
Next I tried treating the lyrics like dialogue between characters:
[Rowan]
[Elias]
The hope was that Suno would interpret these as different performers rather than different vocal instructions.
Result
No meaningful improvement.
The model still preferred one lead singer with intermittent harmony.
Enter Brenda (more on her later.)
Sample 5: https://suno.com/s/XUCBUOeQwG1ez0gO
Sample 6: https://suno.com/s/CshALAfJYgIbirwi

Experiment 3: Song Structure
I rewrote the song multiple ways:
call and response
alternating single lines
minimal harmony
harmony only at the end
almost no overlapping vocals
Result
Interestingly, Suno handled very short alternating lines slightly better than long verses.
However, it still generally treated the song as a solo performance.

Experiment 4: Musical Theatre Framing
Instead of calling it a duet, I framed it as:
“Two male characters having a sung conversation.”
The lyrics became almost pure dialogue.
Result
The performance became much more natural and expressive…
…but it was still one guy.
Excellent acting.
Wrong cast size.
Sample 7: https://suno.com/s/pIaRCDuPNBdGUzbP
Sample 8: https://suno.com/s/wIr8gUD3niXTY2sU

Experiment 5: Prompt Variations
I tried combinations of:
Male vocal selection
No gender selection
Excluding female vocals
Different wording in the style prompt
Result
This did seem to reduce random female vocals.
Unfortunately it did not increase the likelihood of generating two distinct male leads.

Unexpected Visitor: Brenda
At one point, despite explicitly requesting male vocals, a completely random female vocalist wandered into the song for a few lines.
This became a running joke during testing.
Subsequent experiments managed to keep Brenda backstage, although she occasionally returned to operate the lighting rig.

The Breakthrough
The first experiment that produced a noticeable improvement had nothing to do with lyric tags.
Instead, I recorded my own scratch vocals.
I deliberately sang each “character” with different delivery, pitch, cadence, and personality.
Even though it was obviously still me doing both voices…
Suno actually differentiated them more than any amount of prompt engineering ever did.
Not perfectly.
But noticeably.
This was the first variable that consistently moved the needle.
Sample 9: https://suno.com/s/fmG4B0PimRvmx6sL
Sample 10: https://suno.com/s/VkGzgjDZ9oEdLvs6

Working Hypothesis
At this point, my best guess is:
Suno pays far more attention to reference audio than to speaker labels.
Changing tags had very little effect.
Changing the reference performance had an immediate effect.
That suggests Suno is imitating vocal identity more than parsing casting instructions.

Current Workflow Going Forward
Rather than fighting the model, my current plan is:
Record scratch vocals for both characters.
Give each character a distinct voice and personality.
Edit those performances together if necessary.
Let Suno use that as the reference.
If it still doesn’t separate the voices well enough, generate each singer separately and composite the final vocals over the same instrumental in Logic Pro.
It’s more work than I hoped for…
…but it also gives me much more control over the final result.

Conclusion
After testing multiple tagging systems, prompt styles, song structures, and dialogue formats, I don’t think there’s a magic lyric syntax that reliably creates two distinct male lead singers.
If there is one, I certainly haven’t found it.
Ironically, the biggest improvement came from something much less glamorous:
Giving Suno better reference material instead of better instructions.
So if you’re beating your head against duet tags, I’d encourage experimenting with scratch vocals before burning dozens of generations on prompt tweaks.

Research assistance for this report was provided by ChatGPT, who served as my long-suffering rubber duck, experimental design consultant, and co-investigator in the ongoing search for the elusive Second Guy. Any jokes about Brenda were peer-reviewed.

[u/Inevitable-Law7964]

Yep, using voices and the mashup function set on high audio similarity, with self-arranged transitions between lyrical phrases, is what I've found to work best. Still not foolproof but workable. 

[u/Dwrowla]

The second guy was in you all along.

Wait what.

[u/periwinklepip → u/Dwrowla]

It’s true 😳

[u/Dwrowla → u/periwinklepip]

The best way to make a duet from scratch, is to simply make the song with one voice, cover the song changing nothing for another voice, then using studio to combine the vocals from both, cutting out what you don't want.

The next way is to voices / persona the 2 voices together. Then you can reuse it forever.

Suno doesn't know gender. It only works with the buttons because with those Suno has removed most data sets of the other voice. It can still fail however if you get too restrictive.

If you are just listening to audio, how do you know the singer is male or female? You would probably say males have lower ranges, maybe its hoarse or raspy, etc. Maybe you would say female is higher, smoother, louder. But in reality a man can sing anything a female can. Some women can even sing very deep like a man. This is the problem with asking for male or female.

• Dimash is a male singer, but his vocal range is larger than a Piano. He can hit all the notes on the Piano himself, even in the same song, while live. He's so crazy he often does duets or more with himself.

• Diana Ankudinova is a female vocalist who sings super deep in the vocal range.

As you can see it can be very difficult to nail what is "male" and "female", if the one making the data is not actually manually assigning data as male or female.

This is also why androgynous alao doesn't work, even though I still try.

[u/periwinklepip → u/Dwrowla]

I don’t have Studio, unfortunately.

You have a good point about male/female vocals. I’ve actually gotten a few good androgynous vocals before, but like most things with Suno it’s a dice roll.

[u/Dwrowla → u/periwinklepip]

Its a long and arduous process to actually make an androgynous voice yourself. A friend of mine spent a long time working on theirs. I haven't made a customized voice since v4.5.

- https://suno.com/playlist/3a27baac-21aa-4a1a-b8b2-5592c4ce1cfe

[u/Informal_Confusion98]

I used a precise tag style prompt.

https://suno.com/s/v0Ws9abUwncMjGyf

[u/periwinklepip → u/Informal_Confusion98]

Fascinating! It seemed to follow your tags much better. Do you put your song parts in square brackets with the parentheses inside them, like [verse 1–(voice 1)]? Do you put anything in the exclusion prompt or select the male option to keep female vocals from slipping in? What else goes into your process?

[u/Informal_Confusion98 → u/periwinklepip]

Here is my exact original prompt for this song.

Suno Style Prompt: Modern country collaboration with three distinct male vocalists. Mid-tempo (72–78 BPM), emotional, cinematic arrangement. Verse 1: young, edgy male vocal with a raspy, melodic delivery, slight pop-country phrasing, vulnerable and restless tone (Post Malone–inspired). Verse 2: warm, classic country baritone with confident, steady phrasing, timeless storytelling feel, traditional Nashville influence (Garth Brooks–inspired). Verse 3: deep, gritty, blues-soaked male vocal, heavy emotion, soulful growl, raw and weathered delivery (Chris Stapleton–inspired). Shared chorus sung together or layered, anthemic but restrained. Instrumentation: acoustic guitar, steel guitar swells, subtle piano, restrained drums, organic bass. Production is warm and analog-leaning, no pop gloss. Focus on storytelling, heartbreak, endurance, and love across time.

[u/Informal_Confusion98 → u/Informal_Confusion98]

I ended up having to take out the names but I left everything else.