I have been reluctant to create this thread as FranQL (FQL) DIY Earbuds are not readily available, nor are they made to sell, but rather are kindly gifted to fellow flathead fiends and earbud lovers that the earbud maker is acquainted with. Upon receipt the other day of another brilliant sounding set of earbuds from our very humble, yet very talented Spaniard I could no longer refrain from, nor resist, putting @FranQL's creations into the spotlight. This thread is a well deserving tribute to the truly extraordinary skills (and magical touch) that some DIYers like our gifted @FranQL have and their true passion for all things flathead.
*** Calling on all other recipients to share their earbud treasures in this here thread. ***
~ ~ ~
The following are the seven (7) earbud models that I have received from @FranQL since 2021:
2023
FranQL Caelum (DIY Metal Bell-Horn Beryllium); 4.4TRRRS; 120Ω
Primary Signature = Neutral Flat / Mid-Centric
Secondary (Strong) = Neutral Flat (Balanced tuning)
Secondary (Strong) = Sharp - Detailed (Reference-Level Detail)
Secondary (Weak) = Slightly Dark Leaning (Resolving Low End)
Tertiary (Complimenting) = Airy - Smooth Treble (No Sibilance)
Tertiary (Opposing) = None
Soundstage = Slightly Narrow but Very Deep (Multi-Layered)
Session = Ultralong (No Detectable Fatigue Yet)
Microphonics = Virtually None
Pros = Balanced; Resolute Clarity; Superb Imaging; Natural Timbre
Cons = Narrow staging may be too weak for some Symphonic Classical / Live Performance recordings
The above breakdown remains tentative and may change after I have had more time with the Caelum.
Timbre is back! Stunning signature. Awesome resolution and clarity. Airy, but with no upper frequency fatigue, brightness, or sibilance to speak of. They remind me a little of my K's 凯 Temperament Bell-Ti 钛铃 High Impedance Edition; 120Ω but with a more pronounced (better textured) low end... and they offer a similar detailed airy upper end that reminds me of my old Simphonio SW-Dragon 3 Plus but sans the fatiguing sibilance and brightness that the SWD3+ and pretty much the entire Dragon series is known for.
The Caelum, if they continue to behave as well as they are, will be headed for first place in my ranking list. The Yinman 2.0 600 LE might have more pronounced sub-bass and wider sound staging but the Caelum bass is far more resolving (better textured) and their staging is deep and layered. With a high sensitivity of 116 dB/mW I did notice something peculiar about this ultra-sensitive driver though... the sub-bass surprisingly perks up, quite significantly, when I switch to high-gain mode on my tube amp which at the moment I am unable to explain the reason as to why that would happen...

The huge plus for me is the improved timbre offered by the Caelum which is due to it's more linear (balanced) sound signature. Being a timbrehead I am beyond pleased to get this level of resolution and clarity back again without the usual associated fatigue and resulting ear/headache that plague me with so many earbuds. I can now hear Leonard Bernstein grunting, humming along, and berating out-of-line musicians again in Beethoven: Choral Fantasy in C Minor, Op. 80 (1962).
2022
FranQL Temperament Woody Edition; 3.5TRRS (3.5MM HIFIMAN); 150Ω
A surprise mod of the K's 凯 Temperament Bell-Ti 钛铃 High Impedance Edition; 120Ω in which @FranQL performed a lifesaving driver transplant; more info here.
"offering a pleasantly warm and ultra-extended listening capable sound signature I have found these modded Ks Bell-Ti earbuds to be more balanced sounding with a nice sparkle in the treble... so definitely more exciting and a tad less gooey and laidback than the original tuning."
2021
FranQL Yellow Candy (DIY MX120 LCP); 2.5TRRS; 127Ω
Primary = Neutral - Bright / Mid-Centric
Secondary (Strong) = Bright (Mildly - Not Sibilant, Nor Harsh)
Secondary (Weak) = Smooth
Tertiary (Complimenting) = Detailed
Tertiary (Opposing) = Dark
Session = Long-Ultralong
Microphonics = Moderate
Pros = Superb Timbre; Perfectly Mid-Centric; Reference-Like
Cons = None, besides some cable microphonics
FranQL Eight Ball Red (DIY MX300 DLC Carbon); 3.5TRS; 300Ω
Primary = Neutral Flat / Mid-Centric
Secondary (Strong) = Smooth & Mellow
Secondary (Weak) = Dark
Tertiary (Complimenting) = Warm
Tertiary (Opposing) = Sharp
Session = Ultralong
Microphonics = Very Minor due to cloth cable
Pros = Super-Smooth; Mellow; Relaxing; Very Friendly Signature
Cons = If underpowered it may be too smooth (boring) with some music genres
FranQL Eight Ball Blue (DIY MX32 19-21 Black Dot Bio); 3.5TRS; 32Ω
Primary = Neutral - Bright (Pseudo V-Shaped) / Mid-Centric
Secondary (Strong) = Very Bright (Though Not Sibilant, Nor Harsh)
Secondary (Weak) = Warm
Tertiary (Complimenting) = Sharp / Detailed
Tertiary (Opposing) = None
Session = Medium-Long
Microphonics = Minor (normal level for MX500 shell)
Pros = Friendly Signature; Excellent Timbre
Cons = Bass-Light (slightly recessed bass); occasionally naughty highs
FranQL Cylon-Be (DIY MX500 Beryllium); 2.5TRRS; 500Ω
Primary = Aggressive / Mid-Centric
Secondary (Strong) = Bright / Ultra Detailed
Secondary (Weak) = Thin-Tinny
Tertiary (Complimenting) = Detailed / Forward - Shouty
Tertiary (Opposing) = None
Session = Short (highs are fatiguing)
Microphonics = Minor (normal level for MX500 shell)
Pros = Reference (Ultra-Detailed); Timbre is good albeit sharp, very sharp
Cons = Critical (can be too clinical/analytical especially with poor recordings); Aggressive
FranQL Darth Gray-Be (DIY MX32 19-21 Red Dot Beryllium); 3.5TRS; 32Ω
Primary = Neutral Flat / Mid-Centric
Secondary (Strong) = Dark
Secondary (Weak) = Smooth
Tertiary (Complimenting) = None
Tertiary (Opposing) = Mildly Bright
Session = Long-Ultralong
Microphonics = Minor (normal level for MX500 shell)
Pros = Bass
Cons = Too dark which at times can be lifeless and boring
*** Calling on all other recipients to share their earbud treasures in this here thread. ***
~ ~ ~
The following are the seven (7) earbud models that I have received from @FranQL since 2021:
2023
FranQL Caelum (DIY Metal Bell-Horn Beryllium); 4.4TRRRS; 120Ω


Primary Signature = Neutral Flat / Mid-Centric
Secondary (Strong) = Neutral Flat (Balanced tuning)
Secondary (Strong) = Sharp - Detailed (Reference-Level Detail)
Secondary (Weak) = Slightly Dark Leaning (Resolving Low End)
Tertiary (Complimenting) = Airy - Smooth Treble (No Sibilance)
Tertiary (Opposing) = None
Soundstage = Slightly Narrow but Very Deep (Multi-Layered)
Session = Ultralong (No Detectable Fatigue Yet)
Microphonics = Virtually None
Pros = Balanced; Resolute Clarity; Superb Imaging; Natural Timbre
Cons = Narrow staging may be too weak for some Symphonic Classical / Live Performance recordings
The above breakdown remains tentative and may change after I have had more time with the Caelum.
Timbre is back! Stunning signature. Awesome resolution and clarity. Airy, but with no upper frequency fatigue, brightness, or sibilance to speak of. They remind me a little of my K's 凯 Temperament Bell-Ti 钛铃 High Impedance Edition; 120Ω but with a more pronounced (better textured) low end... and they offer a similar detailed airy upper end that reminds me of my old Simphonio SW-Dragon 3 Plus but sans the fatiguing sibilance and brightness that the SWD3+ and pretty much the entire Dragon series is known for.
The Caelum, if they continue to behave as well as they are, will be headed for first place in my ranking list. The Yinman 2.0 600 LE might have more pronounced sub-bass and wider sound staging but the Caelum bass is far more resolving (better textured) and their staging is deep and layered. With a high sensitivity of 116 dB/mW I did notice something peculiar about this ultra-sensitive driver though... the sub-bass surprisingly perks up, quite significantly, when I switch to high-gain mode on my tube amp which at the moment I am unable to explain the reason as to why that would happen...
The huge plus for me is the improved timbre offered by the Caelum which is due to it's more linear (balanced) sound signature. Being a timbrehead I am beyond pleased to get this level of resolution and clarity back again without the usual associated fatigue and resulting ear/headache that plague me with so many earbuds. I can now hear Leonard Bernstein grunting, humming along, and berating out-of-line musicians again in Beethoven: Choral Fantasy in C Minor, Op. 80 (1962).
2022
FranQL Temperament Woody Edition; 3.5TRRS (3.5MM HIFIMAN); 150Ω
A surprise mod of the K's 凯 Temperament Bell-Ti 钛铃 High Impedance Edition; 120Ω in which @FranQL performed a lifesaving driver transplant; more info here.

"offering a pleasantly warm and ultra-extended listening capable sound signature I have found these modded Ks Bell-Ti earbuds to be more balanced sounding with a nice sparkle in the treble... so definitely more exciting and a tad less gooey and laidback than the original tuning."
2021
FranQL Yellow Candy (DIY MX120 LCP); 2.5TRRS; 127Ω

Primary = Neutral - Bright / Mid-Centric
Secondary (Strong) = Bright (Mildly - Not Sibilant, Nor Harsh)
Secondary (Weak) = Smooth
Tertiary (Complimenting) = Detailed
Tertiary (Opposing) = Dark
Session = Long-Ultralong
Microphonics = Moderate
Pros = Superb Timbre; Perfectly Mid-Centric; Reference-Like
Cons = None, besides some cable microphonics
FranQL Eight Ball Red (DIY MX300 DLC Carbon); 3.5TRS; 300Ω

Primary = Neutral Flat / Mid-Centric
Secondary (Strong) = Smooth & Mellow
Secondary (Weak) = Dark
Tertiary (Complimenting) = Warm
Tertiary (Opposing) = Sharp
Session = Ultralong
Microphonics = Very Minor due to cloth cable
Pros = Super-Smooth; Mellow; Relaxing; Very Friendly Signature
Cons = If underpowered it may be too smooth (boring) with some music genres
FranQL Eight Ball Blue (DIY MX32 19-21 Black Dot Bio); 3.5TRS; 32Ω

Primary = Neutral - Bright (Pseudo V-Shaped) / Mid-Centric
Secondary (Strong) = Very Bright (Though Not Sibilant, Nor Harsh)
Secondary (Weak) = Warm
Tertiary (Complimenting) = Sharp / Detailed
Tertiary (Opposing) = None
Session = Medium-Long
Microphonics = Minor (normal level for MX500 shell)
Pros = Friendly Signature; Excellent Timbre
Cons = Bass-Light (slightly recessed bass); occasionally naughty highs
FranQL Cylon-Be (DIY MX500 Beryllium); 2.5TRRS; 500Ω

Primary = Aggressive / Mid-Centric
Secondary (Strong) = Bright / Ultra Detailed
Secondary (Weak) = Thin-Tinny
Tertiary (Complimenting) = Detailed / Forward - Shouty
Tertiary (Opposing) = None
Session = Short (highs are fatiguing)
Microphonics = Minor (normal level for MX500 shell)
Pros = Reference (Ultra-Detailed); Timbre is good albeit sharp, very sharp
Cons = Critical (can be too clinical/analytical especially with poor recordings); Aggressive
FranQL Darth Gray-Be (DIY MX32 19-21 Red Dot Beryllium); 3.5TRS; 32Ω

Primary = Neutral Flat / Mid-Centric
Secondary (Strong) = Dark
Secondary (Weak) = Smooth
Tertiary (Complimenting) = None
Tertiary (Opposing) = Mildly Bright
Session = Long-Ultralong
Microphonics = Minor (normal level for MX500 shell)
Pros = Bass
Cons = Too dark which at times can be lifeless and boring
Last edited: