TRN STM Review (2) – Transformers, Different Tunings In Disguise
Pros
Light, good fitting and comfortable.
Good price to performance ratio.
3 tuning filters to give different sound signatures (not gimmicks).
Good imaging, details and soundstage for the price.
Easily drivable.
2 pin cable connector – better lifespan than MMCX.
Cons:
Artificial BA timbre for treble frequencies, not best option for acoustic instrument/vocal predominant genres.
Upper mids and treble can get shouty/harsh on gold and blue filter.
Thin note weight.
EXECUTIVE SUMMARY
The TRN STM is a budget CHIFI brightish U-shaped hybrid that offers 3 tuning nozzles to finetune the sound signature. It has good price to performance ratio and good technicalities for the price. A nitpick would be the common artificial BA timbre for acoustic instruments and thinner note weight. Don’t be expecting a tour de force for the price, (and keep your expectations in check), but I think its very decent value for 20ish bucks.
SPECIFICATIONS
- Driver unit: 1DD+1BA hybrid unit
- Impedance: 24 ohms
- Earphone sensitivity: 106dB/mW
- Frequency range: 20 – 2000Hz
- Earphone interface: 2Pin
- Tested at $22 USD
ACCESSORIES
In addition to the IEM, it comes with:
1) Silicone tips (S/M/L).
2) Stock cable – generally usable sonic wise, no chin cinch, slight microphonics.
3) 3 pairs of tuning nozzles to change the sound signature
BUILD/COMFORT
Though the TRN STM looks a bit cheap in appearance, it is very light, comfortable and well built. No issues with wearing it for long sessions.
I didn’t detect any driver flex.
I’m not a fan of MMCX connectors due to potential longevity issues, and am glad the TRN STM came with a 2 pin connector.
ISOLATION
The TRN STM has slightly above average isolation, not as good as some unvented BA types, but adequate enough for outdoors usage.
DRIVABILITY
The TRN STM is very drivable from lower powered gear like smartphones, so no amping requirements necessary.
SOUND & TECHNICALITIES
The TRN STM on the default gold filter sports a bright U shaped tuning, with some boosted upper mids. The bass actually looks anemic on the graphs, but on actual listening (with a good eartip fit), they are slightly north of neutral and weightier than the graphs suggest (this is coming from a self-professed basshead), with quite good subbass extension.
Some BA (balanced armature) containing CHIFI such as some KZs and the TRN VX didn’t receive the best reviews from non trebleheads for the overly harsh upper mids/treble, probably cause of an undampened BA being nestled in the nozzle, which is a common bugbear for “westernized” ears. The TRN STM still has a BA hiding in the nozzle, but the tuning filters provide some dampening effect with the materials inside their nozzles, and this is a great move from TRN, to not only let one finetune the sound signature, but also to help to dampen the upper mids/treble glare for our treble sensitive breathen.
As per the graph below, there are 3 tuning filters which mostly affect the 2kHz – 5kHz regions (though some of the sound impressions may not correspond to the graphs, eg bass quantity and upper treble):
- Gold filters (stock) – make the sound “balanced and natural” according to the TRN store page. I dunno how TRN is marketing the gold filters as “balanced and natural” as it sounds like a bright U shape with boosted upper mids to me actually (the red filters sound more “balanced” for me). I find the upper mids more forward with this gold filter, with perceived depressed lower mids, and the upper mids can get hot sometimes, though it isn’t as bad as some other CHIFI offenders in terms of upper mid glare (cough cough some KZs, and the recent TRN-VX big brother). The subbass is actually quite well extended, more than the graphs would imply. Treble extension with gold filters is quite good. Perhaps for the local mainland tuners, this sound is “balanced and natural” to them, but I think treble sensitive westerners may need to try the red filter as this gold filter can get fatiguing with longer sessions at the upper mids area especially.
- Blue filters – makes it have a “resolving treble” according to the TRN store page. Of the 3 descriptions of the various filters above, this sounds (no pun intended) the most legit. The bass is perceived to be decreased with the upper treble being at the forefront, with more details in the treble heard. Not my cup of tea as the excessive details can get fatiguing with longer sessions, but detailheads and trebleheads may like it. The upper mids on this tuning filter is just slightly less than the gold filters.
- Red filters – “deep bass, fast transient” according to the TRN store page. The red filters does make the upper mids glare lesser and reduces treble a tinge compared to the stock gold filters. This is my preferred tuning filter, and actually sounds the most balanced of the 3 and it makes the TRN-STM to be more vocal centric. The subbass seems to be of about the same quantity and extension as with the gold filters, not sure why the store pages say it is “deep bass”.
So the tuning filters thankfully work to change the sound signature, and ain’t gimmicks (cough cough LOOKING AT YOU NiceHCK M6), though it may not exactly correspond to the store page’s description.
Bass as discussed above is quite dependent on the filter used, but the bass is generally on the punchier side, with midbass > subbass in quantity. Bass is quite fast and has slightly above average texturing. Mids are generally boosted at the upper mids across the different filters, and the treble is also on the brighter side, with good extension and details. Those that are sensitive to the usual CHIFI saw tooth upper mids and treble will likely appreciate the red filters the most.
Technicalities are good for the price, with great imaging, details and imaging at this price bracket. Soundstage is also good, with it being wider and deeper than tall, but nevertheless, music didn’t sound too congested on this set even with complex music. I liked that transients are rather fast on this set. Cymbals are occasionally splashy but ain’t as artificial as some other budget contenders.
For a budget hybrid, the TRN STM’s tuning is quite coherent actually, even with the various filters placed on, I didn’t really hear a significant crossover point on the TRN STM.
Unfortunately, timbre is poor for acoustic instruments, especially at the frequencies handled by the BA driver, so those that listen to predominantly acoustic instruments or who are vocal lovers might need to look elsewhere. Note weight is also on the thinner side, would have preferred more meat in the bones, so to speak, but these are small issues in the big scheme of things, considering the $22 USD asking price.
CONCLUSIONS
The TRN STM is a very decent budget CHIFI brightish U shaped hybrid that offers 3 tuning nozzles to finetune the sound signature. As such, it opens different permutations for sound signature in the music and can cater to both trebleheads and treble sensitive folks. It has good price to performance ratio, especially in the area of technicalities. However, a nitpick would be the usual BA timbre for acoustic instruments found in budget hybrids, with a leaner note weight.
The $20ish CHIFI market is ultra competitive, but I think TRN STM’s tuning filters will give it an extra feather in its cap when it comes to potential sales. In fact, one can even see it as getting 3 IEMs for one purchase when getting the TRN STM, due to the 3 different tuning nozzles (which are thankfully not gimmicks), giving different sound signatures.
At this price segment, I like this set more than the recent KBEAR KS2 and CCA C10 Pro (in terms of timbre/tonality), but it still loses to the KBEAR KB04 as an overall package, other than the tuning filters. So, don’t be expecting a tour de force for the price, (and keep your expectations in check), but I think the TRN STM is still extremely decent for 20ish bucks. I’ll probably be stocking up on a few sets to give as Christmas gifts this year.
MY VERDICT
You find an INDEX of all our earphone reviews HERE.
DISCLAIMER
I would like to thank the TRN Official Store for providing the TRN STM review unit.
It can be gotten at $22 USD from https://www.aliexpress.com/item/4001282484099.html
Our generic standard disclaimer.
You find an INDEX of our most relevant technical articles HERE.
