Penon Turbo

First of all I would like to thank Penon Audio. She supplies me with the turbo for a tour in Germany. I would like to publish my review here on Head-fi. I used Chat GPT to help with the translation. I hope this doesn't affect readability too much. I became aware of the Penon brand through a dear friend who is currently no longer active in the community. He had organized the Penon Serial Tour back then. The series remains in my memory because of its excellent tone.

For everyone who is in a hurry:
Advantages:

• Pleasant musical performance
• Still excellent detail
• Very good separation and instrument positioning in this price range
• Above-average sound in this price range
• Cable without microphones
• The tuning system enables an extremely variable sound (from audiophile to bass-heavy).

Disadvantages

• (Turbo) bass switch may not be suitable for audiophile interests

First I would like to briefly introduce my musical experiences and my equipment:
Musically, I'm at home in rock & metal, but I also like to listen to some pop, currently also from my youth, which was a few days ago. I prefer a balanced, slightly warm tonality. However, I don't want to miss any details. The bass should be strong, but not dominate the mix or go into the middle. Good instrument separation, combined with good positioning, enhances the musical experience and creates a comfortable stage. However, too much energy in the upper midrange spoils my enjoyment of music.

The Turbo was heard on the A&K SP2000T and was compared to the ACTIVO CT10, A&K PEE51 and A&K XB10.

Package contents
This time the Turbo arrived without any additional packaging. This is not relevant to the evaluation of a tour and avoids additional waste. In the typical Penon blue hard-shell housing, we find the well-known CS819 cable (silver-plated OCC) from the series next to the earphones. The braided cable is soft and supple, not too thick and does not produce microphonics. Additionally there are 3 different 4.5mm silicone tips (grey-green, clear-red and clear-green). The package is supplemented by tools for cleaning the sound outlet pipes and adjusting the tuning switch.





Comfort
I was a bit biased, especially when it came to tightness. Previously, I always had problems when IEMs had a printed seat for the eartip. The position of the tip was then not fully defined and the tip could move backwards when inserted into the ear. This made complete sealing difficult or impossible. This was a dealbreaker for me, even with 64Audio IEMs. That's why I prefer IEMs with metal sleeves etc., like those from Penon Serial or Thieaudio. Fortunately, things are different with the Turbo. The tips are defined and firm and do not push back on the tube during insertion. This eliminates the need to frequently adjust the fit in the ear and ensures a perfect seal. Once the turbo is in your ear, you quickly forget about it and can concentrate fully on enjoying the music. The Penon standard cable, as already mentioned, is microphone-free and offers good resolution and tonality. To my ears it plays very musically. If you are already happy here and hear a lot of switch details depending on the position of the tuning, an upgrade may not be necessary.

Tuning-System
Over the course of my HiFi journey, I have heard or owned several IEMs with a tuning system. As examples I would like to mention Shure with interchangeable sound tubes and IMR Acoustics with a tube and filter system. In both variants, the components have to be screwed together, which takes some time. Penon has chosen a switch system that can be adjusted easily and without much effort from the outside. The system consists of 4 switches in two groups:



Single switch (Bass Boost)
Switch 1 on the left is a bass boost switch. It can be used together with the other 3 switches or independently. When used independently, it is a low frequency super boost mode. The remaining 3 switches from group 2 can be used to further change the sound, including the bass.

3-switch system (tuning)
The number corresponds to switching on and 0 to switching off:
100 – Low frequency gain
020 – Emphasis on the voice
003 – High frequency amplification

Sound
In all three tuning modes, the Penon Turbo has a rich bass that doesn't necessarily sound like a balanced armature (BA) bass. It can provide volume and fullness while remaining clean and accentuated. There is no booming sound in the lower middle as long as you don't use the turbo switch. This is ensured by the lowering of the frequency response immediately after the bass. The rest of the vote does not show any outliers that would disrupt the enjoyment of the music. The mittens are perfectly coordinated and are slightly forward facing in the mix. Guitars have bodies and an excellent timbre. You can follow the attack of the string acoustically. The vocals are slightly in the foreground and, like the overall mood, are very clear. Even at high altitudes, the turbo shows no weaknesses. They sound BA-like, smooth and detailed. There are no hissing sounds or sharp hissing sounds. The sound is very good in the price range, but not oversized like the Sennheiser HD800, for example. This is due to the not very pronounced tuning in the air frequency range. As already mentioned, I find the Penon Turbo extremely successful with its musically detailed playing style.

Influence of the tuning system
In my opinion , the individual bass boost or turbo switch is not suitable for audiophile enthusiasts. When activated, the boost is very powerful and the bass penetrates into the middle. The sound reminds me a little of the Fatfreq Maestro Mini. However, the Maestro Mini had even more bass energy. The Turbo avoids the sharp upper mids and highs presentation that the Maestro Mini had.

The 3-switch system represents (fine) tuning because it works much more subtly than the turbo switch. At first, since I came from the Penon Serial, I often listened with the setting 0-123. With this setting, the Turbo already has an infectious musical bass and the overall colorful playing style that Penon is familiar with. Finally, I would recommend it for albums from before the turn of the millennium to bring the sound up to date.

In my opinion, the settings 0-020 and 0-023 are suitable for current productions when you want to emphasize the tone towards the black background, separation and stage. Whether you adjust the height switch is ultimately a question of privacy and music production. Even age-related hearing loss at high frequencies could be compensated for with the third switch. For example, the album “Ghost – Opus Anonymus” sounded better to me with 0-023 than without the treble switch. The vocal setting 0-020 can sound brilliant on very well produced music and make additional details more audible.

EQ
Basically, the Turbo is suitable for me for playlists. My playlists contain titles from the late 60s, good and not so good recordings, originals and remasters. Fortunately, the Turbo is an earpiece that allows listening across decades and productions without the need to constantly change tuner switch settings. If you still want to work on tuning, the Turbo is an IEM that responds well to EQ. I've only experimented with minor corrections. For example, you can slightly fill in the small depressions in the transition to the lower mittens to create more mittens and counteract the V-shaped tuning. Perhaps a slight lowering of the mid-bass could be considered if the production is over-mastered. Otherwise, “central bleeding” can occur. Without these fixes the turbo will remain clean and clear. Increasing the air frequency range can be beneficial if the music you listen to is too bass heavy or you simply prefer it. I quickly got used to the dynamic playing style of the Turbo and was therefore able to forego the use of an EQ.

Ear plug
The sound can also be subtly influenced by the tips included in the package:
The gray-green tips provide high-frequency extension, amplifying the fundamental tone and improving the sense of space and layering. On the other hand, the clear red tips reduce sibilance, bring the vocals forward and make the music sound more balanced overall. The clear green tips also deliver clear voices and slightly improved details due to the reduced fundamental tone. I also like to use the Softears silicone tips, which seal perfectly for me due to their shape and thus amplify the bass. Even though they are intended for TWS (True Wireless Stereo), Spinfit CP360 goes in a similar direction. Spinfit W1 brightens the sound while Azla Crystal sits between the two. Spinfit CP145 makes the sound a little slimmer and more balanced.

Music examples
Finally, I would like to talk about a few songs. The following descriptions are based on the A&K SP2000T:

Dream Theater – Octavarium & Avantasia – The Scarecrow
Both are my epic reference songs. The Scarecrow opens with some drums that sound powerful but dry. During the song, the guitars and drums show me whether the IEM is designed for effects. Then it quickly becomes tiring. The Turbo does an excellent job of reproducing many details throughout the song. With Octavarium it's the keyboard passages that sound very natural and let your mind wander. As the engine progresses, the turbo never loses control despite the increased number of instruments. Everything remains clean and absolutely audible; it never sounds too analytical. Luckily, guitars aren't scalpels; they don't sound too thick, too sharp or too thin. A thin-sounding IEM can quickly become annoying, especially in lead guitar solo passages from Dream Theater. Very good spatial effects can be heard in both songs.

Jefferson Starship – Jane & Freedom at Point Zero
The entire album contains songs or guitar riffs that can be quite challenging for listeners who are too bright or focused on presence and effects. The electric guitar can sound very shrill or scratchy. Fortunately, the Turbo doesn't show these effects, but still offers an excellent presentation. The stars of the song are clearly the guitars, which have an excellent texture. The bass plays minimally in the foreground and the synthesizer sounds absolutely authentic.

Ghost – Phantom der Oper (Iron Maiden Cover)
The guitars sound almost magical with a perfect body, simply impressive. The album Phantomime is modern and “weighty” in the mix. The turbo stays clean on the drums, and the separation and vocals also sound very good as usual. The (lead) guitar sounds confident and doesn't stand out from the mix.

Sophie Lloyd (feat. Michael Starr) – Runaway
My Focal Clear is having a bit of a hard time (separation) here because the drums and riffs are mixed really thickly. Not so with the turbo in position 0-023. Here he can take advantage of the speed of his BA drivers and play the songs much cleaner and still convincingly. Similar to the Maiden cover of Ghost, the dip between bass and mids no longer plays a role. In both songs I find the balance between musicality and details perfect.

Serenity – Wings of Madness & New Horizons
These songs are a benchmark for good bass rumble, and the Turbo does a great job of reproducing it.

Purple Disco Machine – In the Dark
Even though I mostly listen to rock and metal, this is a reference song for a successful modern mix. With clear female vocals, we have super-fast reproduced synthetic drums and beautiful micro details.

Whole Lotta Love – Led Zeppelin
I mean, that's how Zeppelin would have liked to hear the song. The guitar riffs start with a wonderful scratch, the bass line fits perfectly without dominating, and Robert Plant sounds like he was in his best days.

Comparison with other IEMs
For me, the Turbo represents a further development of the Penon Serial, even if one would generally assume that this is reserved for the Penon Quattro. However, I haven't heard the Quattro yet. Compared to the Turbo (0-123), the Penon Serial is tuned relatively similarly. Both music IEMs offer enhanced bass with warm tonality. However, the Turbo excels in resolution and soundstage.

The Penon Fan 2 is characterized by a solid fundamental tone and avoids increasing the deep bass, making it sound very balanced. However, it lacks the expressive midrange of the Turbo. Here too, the bass is noticeably less defined and enveloping due to the DD drivers.

Another competitor is undoubtedly the Softears RSV (5BA), which in my opinion has a leaner bass and is tuned too energetically in the highs.

On the other hand, the Penon Impact is a TOTL (Top Of The Line) IEM that plays above the turbo due to its performance. The bass is less pronounced and even clearer. When playing electric guitars, the mids have a somewhat magical feel to them. Thanks to the EST drivers, the highs are more energetic and reveal additional details.



Tone on tone
A green petrichor zombie cable. Which tips do you prefer, gray-green or clear green?

Conclusion
As you can easily see, I really like the Penon Turbo because of its musically detailed playing style. The 6 BA drivers work perfectly together to enjoy a wide range of music. However, they lean more towards the musically detailed side of the spectrum. They shine with beautiful details from the mids onwards. Anyone looking for an absolute analyzer should look elsewhere. The turbo accelerates and captivates me with its musicality. Over the years, I have heard many IEMs from Dunu, Moondrop, 64Audio, Thieaudio, etc. that were priced up to $2.5k.

Hardly any headphones have impressed me as much as the Turbo, apart from the unfair comparison with TOTL IEMs like the Penon Impact or the Thieaudio V16 Divinity.

Disclaimer

• Huge thanks to Penon for providing the opportunity for me to review the Penon Turbo through a discount on the Turbo. I really do appreciate it. However, all thoughts and opinions are my own, and are not influenced in any way.
• Please take this review with only a grain of salt, as everyone's hearing, fit, and gears may differ, so our experience may be different.

Price(MSRP)

• $549.00

Source(s)

• Surprisingly easy to drive, even the budget oriented JM6 Pro is sufficient to power it easily with the volume being lower than 50%.
• Source used:
  • Topping DX1 (preferred)
  • Truthear Shio
  • Jcally JM6 Pro

Ear tips

• Dunu S&S

Packaging

• Penon Turbo.
• Hard case with a soft, smooth texture
• Small leather pouch
• Cleaning brush
• Pin for tuning switch adjustments
• Shirt clip
• Good selection of ear tips.
  • 9 pairs of generic silicone ear tips (S, M, L)
• Leather cable tie
• Penon CS819 OCC & Silver-plated Mixed Braided HiFi Audiophile IEMs Cable
  • Feels very well built, soft and comfortable to wear, doesn't come with a ear hook though.

Build Quality

• Build quality is alright, not the best.
• Shell is made entirely out of resin, very lightweight as well.

Fit

• Nozzle length and width is average, but note that it can get a little slippery for certain ear tips as it is made out of resin.
• Fit is extremely comfortable for me, due to its very small shell size and how light is it, which is not common at all for an IEM that has 6BAs
  • Some popular 6BA IEMs like the Elysian Diva and 7th Acoustics Supernova have really chonky shells.
• Very well vented, no pressure build up issue at all in my experience.

Tonality

• Neutral-bright to L-shaped, extremely versatile tuning switch implementation in my opinion.
• I will only describe the tuning profiles with drastic changes.
• As for the description below, I will use the format of (x-xxx), where the first x represents the turbo switch, and the xxx after that represents the remaining 3 switches in order. 0 means that it is turned off or down, 1 means that it is turned on or up, and x means that it does not affect much whether that it is off or on.

Tuning Profiles

• 0-000
  • Invalid profile according the official Penon site.
  • However, I find this quite listenable, and it may appeal to some people.
  • Neutral-bright signature, most open and transparent. Female vocals sounds the most light and airy in this signature. Details can be perceived the most easily in this mode.
  • However, it lacks body and note weight in this mode due to insufficient lower end response.

• 0-001
  • Slightly bright tilted mild V-shaped signature.
  • Bass is still present, still with amazing qualities
  • Lower midrange sound a bit cleaner than other signatures.
  • Slightly favors female vocals, male vocals slightly lacking weight but treble has good amount of sparkle and crisp, plus it doesn't get harsh in any way at all.

• 0-01x
  • Mild-V shaped signature.
  • Most balanced signature out of all the profiles in my opinion.
  • Bass is more a bit prominent but still remains well controlled.
  • Lower midrange comes with a little more weight. but I would still say it is fairly clean and open.
  • Doesn't favor any side of the vocals, both male and female vocals sound equally good on this setting.
  • Treble has just enough sparkle to push through it to balance it out with the lower end energy.

• 0-1xx
  • Slightly warm tilted mild V-shaped signature.
  • Bass is a bit more dominant compared to other frequencies
  • Lower midrange comes with a bit more warmth and lushness but not to the point of muddy and bloaty.
  • Slightly favors male vocals, female vocals tend to get a bit masked in this profile.
  • Treble is also slightly overpowered by the lower end, but this makes it into a more relaxing listen.

• 1-xxx
  • Bassy, L-shaped signature
  • Insane amount of bass, which easily overpowers other frequencies.
  • Still remains somewhat clean due to the bass tuck.
  • May have pushed the drivers a little too hard, distortions can be heard fairly easily.
  • Only suitable for certain genres like EDM, or based on your mood at that time.

Bass

• The bass is quite balanced between the sub bass and mid bass, perhaps leaning slightly toward the mid bass
• Snappy, good rumble and slam, well textured and controlled, very impactful, have decent body and weight to it.
• Have a woofer effect due to to bass tuck, sounds slightly detached from other frequencies but makes it quite unique and very fun to listen to.
• I would only have minor nitpicks for the bass, that being lacking in bass definition as the bass sounds a little mushy, and it isn't as full sounding as some people prefer due to the bass tuck.
• Quantity can be easily adjusted through the switches, ranging from bass head level to no bass at all.
  • Bass quantity affects many other factors, such as note weight, tonal balance, and overall timbre presentation.
  • When the Turbo switch is turned on, the bass starts to lose some of it qualities like control and naturalness, and it starts to distort, sounding as if the bass drivers are being pushed to their absolute limits.
• Overall, the bass performance is spectacular and is one of the highlights of the Penon Turbo, especially considering that the BAs are completely handling the bass!

Midrange

• Overall midrange is slightly recessed from the bass tuck,
  • However, it isn't as thin as other IEMs that has a bass tuck, probably due the tuck being a bit
• Lower midrange can get from slightly warm to slightly cold depending on the chosen switch profile, but deeper vocals tend to sound quite far away due to the recession.
• Upper midrange is quite energetic and is very smooth to listen to.
• Vocal performance depends heavily on switch profile,
  • More bass will introduce more heft and lushness to the vocals but it will also bring in some huskiness and mask over the clarity.
  • Less bass will make vocals have a more angelic and airy presentation but losing some weight.
  • Fortunately, I found a very balanced setting for myself through the switches, which is 0-01x, that offers a perfect balance of weight and clarity.
• Timbre is decent and natural enough to me for most of the profiles, with the 0-000 and 1-xxx being the exception. However, don't expect the most natural timbre due to the bass tuck and recessed midrange.
• Overall note weight ranges from slightly dense to lightweight depending on profiles as well.

Treble

• Treble is overall quite smooth with just enough sparkle to balance out the lower frequencies on most profiles.
  • On profiles that has less bass, treble tend to be a bit more forward but not enough to be overly bright or sibilant to me. At most, cymbal clashes and vocals have a bit more bite to them.
• Treble extension is good, which add some air to it.
• Details can be perceived pretty well due to how extended the treble is without being dark.

Technicalities

Resolution

• Resolution and detail retrieval is decent, the Turbo isn't really lacking in details but it isn't outstanding either considering that it is a full BA set and the $550 price tag.

Soundstage

• Soundstage is average in terms of width but is decent in terms of depth.
• Not really intimate but isn't exactly very wide or spacious, not the best for the price.

Imaging

• Imaging and accuracy is very good, I am able to pinpoint position accurately with ease.

Separation

• Separation and layering is impressive.
• Every instruments are layered very well among each other, nothing will sound congested at all, even on extremely busy tracks.

Conclusion

• Overall, the Penon Turbo is very well tuned in all departments, backed up with good enough technicalities, and can be further customized with its well implemented tuning switch system.
  • The tuning switches does not changes the overall tuning style.
  • Instead, it changes the "flavor", with minor adjustments towards different tilts, just like how people enjoy different flavors for different genres or different moods.
  • Furthermore, there is even a dedicated switch just for bass heads, but it is a little niche.
• Personally, I am very happy that this is my first endgame TOTL IEM due to its insane versatility and bass quality.

Thanks for reading!

Today, we talk about Turbo, an IEM with 6 Balanced Armature (BA) drivers and 4 tuning switches from the audio retailer and manufacturer Penon.

Forewords​

• What I look for in an IEM is immersion. I want to feel the orchestra around me, track individual instruments, and hear all of their textures and details. I’m not picky about tonality, as long as it does not get in the way of immersion.
• I rate IEMs within with a consistent scale from 1 (poor) to 3 (Adequate) to 5 (outstanding). Ratings are assigned by A/B tests against benchmark IEMs, regardless of the retail price.
• Ranking list and measurement database are on my IEM review blog.
• Terms used in my reviews are consistent with the glossary by Headphonesty
• The IEM used in this review was privately sourced. This review is not supported, enabled, or coordinated by Penon in any shape and form.
• The unit retails for $550 at the time this review was published.

Testing setup: Local FLAC files -> iBasso DX300 (stock player app) -> stock cable (4.4mm) -> IEM -> Spinfit CP100 M

Non-sound Aspects​

Turbo feature transparent and hollow acrylic shells similarly to handmade custom IEM (CIEM). The construction of the earpieces looks and feels better than the hollow injection moulded shells used by many budget IEMs. At the same time, it is lighter than the dense 3D printed shells increasingly used by mid- and high-end IEMs with multiple drivers. Interestingly, there are pressure release vents on the earpieces.

Similarly to most handmade CIEM, Turbo have acrylic moulded nozzles rather than standalone metal nozzles. The nozzles of Turbo are medium in both length and width, with lips to prevent the eartips from falling off.

Subjective Experience​

As usual, we start our discussion of the subjective experience with fit and comfort. Thanks to the small and light shells and medium nozzles, Turbo is a very comfortable IEM. For this kind of IEM shells, your comfort would depend solely on your choice of eartips. I settled for CP100 ear tips in medium size. With this combination, I achieved great comfort in long listening sessions.

How does Turbo sound?



Before going into details, it’s important that we discuss about the tuning system of Turbo. The system comprises 4 switches, including 1 standalone “turbo” switch and 3 switches labelled from 1 to 3. In this article, I will use the text string 0-000 to denote a switch combination (0 means off or down). Even though there are 4 switches, there are only 5 sound signature:

1. TURBO bass (1-xxx): The bass dominates the entire frequency spectrum. The bass boost extends well into the midrange. I don’t find this signature to be usable.
2. MOAR bass (0-1xx): The preferred signature as per Penon’s website. Coincidentally, I also prefer this signature. The bass is noticeably boosted in this configuration, though the tonal balance is not as off as the TURBO mode.
3. Above neutral bass (0-01x): This signature aligns with many “neutral-with-bass-boost” IEMs. The bass is balanced against the upper midrange.
4. Below neutral bass (0-001): In this signature, the tonality leans toward upper midrange, though the bass is not completely absent.
5. Where is the bass? (0-000): Penon declares this signature “invalid.” Still, I think it would appeal fans of Etymotic studio reference response.

You might ask: “how come there are only 5 signatures instead of 16?” I’ll show you when we look at the frequency response of this IEM. Before that, let’s talk about how Turbo sound by analysing some test tracks.



The first test track was “Now We Are Free” performed by 2Cellos. Why this track, you might ask? I picked this track because it is a nightmare for most IEMs with warmer sound signature: the combination of two cellos and the the cello section of the orchestra can quickly “clog” up the lower frequencies and collapse any illusion of separation and details. Turbo does a good job, though not perfect, with this track. From the first note of the cellos, I was immediately satisfied by the rich and rather pleasing tonality of the cellos. The success in tonality can be found in other instruments in the orchestra as well. Turbo also showcases good instrument placement, particularly the depth contrast between closer and further away sounds, such as the contrast between the cellos at the front and violins at the back at around 1:20 mark.



Where Turbo faltered was the instrument separation. For example, around the 2:00 mark of the track, I found myself subconsciously hold my breath because I needed to focus harder to try and separate the increasingly congested midrange. On the plus side, other warm IEMs in my collection, such as the Symphonium Meteor and the Campfire Audio Andromeda 2020, suffer as much as Turbo, if not more. The only way to avoid this congestion entirely seems to rely on a change in frequency response. For instance, by slightly reduce the energy in the lower-midrange region, AFUL MagicOne can cruise through this track without any congestion.



Since Turbo’s calling card is the bass, the focus for my next analysis was bass response. The test track for this analysis was “Victory” from the live performance by Two Steps from Hell. Turbo does an excellent job at the placing the audience’s cheers at the beginning of the track, creating a realistic sensation as if the sound is located around in the room, around me. On this aspect, Turbo does as well as the soundstage specialist Andromeda 2020.

The bass line of Turbo has satisfying thickness, rumble, and decay. To use a more vague term, I would say the Turbo can “slam.” My only criticism here is that the bass notes lack a sharp and clean leading edge. It means that if you prefer your bass to sound snappy and “fast,” you might find the bass to be slightly blunted. However, the bass of Turbo is still carried by BA woofers and thus is never as gooey and “slow” as a less-than-ideal dynamic driver implementation.



Another surprising win for Turbo is the resolution. Simply put, this IEM can pull good details in the midrange. For instance, the vocals around 02:30 mark can match, if not outright exceed, the level of details, textures, and nuances revealed by the Andromeda 2020. One would expect that this level of performance is commonplace in 2024, yet I have rarely seen it, and thus I am quite impressed.



For the last track, we analyse the vocal performance of Turbo by listening to “Can’t Help Falling In Love” performed by Pentatonix. This analysis is rather simple. Turbo renders all vocals with a pleasing and slightly warm tonality. Again, this IEM trades blow with the Andromeda 2020 in terms of the separations of the voices and the texture and nuances within each voice. In a direct A/B test, I found Turbo to comfortably out-resolve the AFUL MagicOne, one of my favourite IEMs with strong technical chops.

Frequency Response Analysis​

Frequency response of Turbo (0100) against the Kinera Phoenixcall and Harman in-ear target. Graphs are aligned at 500Hz. Measurements were done with an IEC-711-compliant coupler and might only be compared with other measurements from this same coupler. Visit my graph database for more comparisons.



It is helpful to think of an IEM as a filter that highlights or subdues different parts of the incoming audio signal. This effect can be measured objectively by the squiggly lines above, called Frequency Response (FR) graphs, which measure how loud an IEM is at different frequencies from 20Hz (bass) to 20kHz (upper treble). Subjectivity is how your ears and brain interpret the effect of that filter on your music and decide whether it is “enjoyable.” There are some “rules of thumb” when it comes to tonality, but most interesting IEMs usually bend the rules masterfully.

As the subjective listening experience suggested, Turbo is a V-shaped IEM that can have anywhere from substantial to unreasonable amount of bass. Interestingly, the frequencies from 500Hz up are quite cleverly tuned. There is a subtle boost from around 1kHz to push the midrange forward, avoiding it from being buried under the mountain of bass. At the same time, Penon ensured that the ear-gain compensation peak of Turbo is placed at the right place, just above 2.5kHz. This tuning choice ensures that the midrange of Turbo sounds natural with just enough “bite.”



The treble was also cleverly done. As suggested by most objective target, Turbo gently rolls off the treble after the upper midrange peak. However, the IEM does maintain an adequate energy level around 8kHz region to ensure that the transients sound crisp.



Why do 4 tuning switches create only 5 signatures? I guess I owe you a proof. Above is the frequency response measurements of three switches configurations (0100, 0110, 0111), measured with the same equipment and configuration. As you can see, there is zero difference. The same situation can be found with other switch configurations, reducing the total number of signatures to 5. Below is the graphs of all five signatures, aligned at 1kHz.

Resolution​

Resolution is a fascinating subject due to the difficulty of pinning down what it really is. To me, “resolution” can be broken down into three components: (1) Sharpness, incisiveness, or “definition” of note attacks (see the figure above). (2) The separation of instruments and vocals, especially when they overlap on the soundstage. (3) The texture and details in the decay side of the notes. The first two give music clarity and make it easy to track individual elements of a mix. The last provides music details and nuances. Smooth and well extended treble response plays a crucial role.

As I mentioned in the subjective experience, Turbo trades blow with and, in some cases, out-resolves the Campfire Andromeda 2020, my benchmark for “great” level of resolution. In fact, due to the tuning choice and stronger emphasis in the upper midrange, you might find Turbo sound much clearer than the Andromeda 2020, though the level of details and separation are roughly the same when paying attention. I would consider Turbo to be “great” in terms of resolution (4/5).

Soundstage Imaging​

Stereo imaging or “soundstage” is a psychoacoustic illusion that different recording elements appear at various locations inside and around your head. Your brain creates based on the cues in the recording, which are enhanced or diminushed by your IEMs, your DAC, and your amplifier. Some IEMs present a wide but flat soundstage. Some present a “3D” soundstage with layering, depth, and height. In rare cases, with some specific songs, some IEMs can trick you into thinking that the sound comes from the environment (a.k.a., “holographic”)

The theme of great technical performance continues. As I mentioned in the subjective experience, Turbo has the ability to place and layering instruments to keep up with the venerable Andromeda 2020. The Andromeda still has a slight edge in terms of the shape and structure of the stage, though I don’t find that difference to be practically significant. I do wish that the soundstage can be even more open and airy, though I don’t think such a stage can be achieved with the tuning choice of the Turbo. All in all, I consider the soundstage imaging of Turbo to be “great” (4/5)

Rating and Conclusion​

I must admit that I approached Turbo with a fair share of scepticism due to various factors. However, I was pleasantly surprised that not only my scepticism was overturned, my expectations were exceeded. Turbo is a well-crafted, versatile, and technically competent IEM that has been tuned with character. If you are looking for the “next step” IEM, Turbo receives a recommendation from this reviewer.

Absolute Sonic Quality Rating: 4.5/5 (Tonality: 4/5; Resolution: 4/5; Spatial: 4/5; Bass and Dynamic: 5/5)

Bias Score: 4/5 (I like this IEM)

Value proposition: Very high





Updated: January 7, 2024