3 portable on-ears: Koss PortaPro, Senn PX100-II, AKG K403

Discussion in 'Audio Science' started by Biodegraded, Oct 28, 2017.

  1. Biodegraded

    Biodegraded Friend

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    Measurements and listening impressions of three comparable lightweight, folding, open & semi-open portable units:

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    Koss PortaPro (left): mfr specs 60 Ohm, 101 dB @ 1mW; familiar to many here. See some discussion here, @Bill-P 's mods and some more discussion here, and @ultrabike 's measurements of a possible fake here. Currently $42 at Amazon US for this grey/blue version.

    Sennheiser PX100-II (middle): 32 Ohm, 114 dB (/V?); second version of a design that’s been around a while. Currently $70 at Amazon for the plain-wire version; also available with inline mic/remote.

    AKG K-403 (right): 32 Ohm, 118dB/V; discontinued but available from marketplace sellers via Amazon from $34. Semi-open design, bigger drivers (~40 mm) than the other two.

    Each of these fold up for transport. The PortaPros have a hook and complementary slot built into the headband to keep them secure, and the K403s have the two-way pivoting-pad design shared by many AKGs. The headband on the PX100-II is in one piece with two pleather pads, whereas the other models have a two-piece sliding arrangement with the K403 having a foam pad under each slider bracket. The Senn is the most comfortable but the AKG feels the most secure on the head thanks partly to the bigger pads/drivers.

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    Measurements

    Measurement setup is as described here, except that SPL calibration is improved by referencing to an external signal and SPL meter. Main shortcomings FR-wise are too much rolloff in the bass, too high around 5-5.5k, too low c. 7-11k, and with full-size phones at least (doesn’t seem to be reflected in the two smaller of these three), a hole around 3.5k.

    Measurements were referenced to 80 dB @ 1kHz, because no matter what I tried with software and hardware I couldn’t avoid clipping at the PortaPros’ 5k peak at anything higher. This has the effect of making my usually atrocious distortion measurements look better so for comparison I’ve included them below; but it should be borne in mind that they’d look much worse at the usual 90 or 100, and might not scale the same way relative to each other with increasing SPL. PortaPro first, PX100-II second, K403 third, then FR and impedance for all 3 together:

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    The long ridge around 3k on the PX100-II right-channel CSD looks suspicious. I didn’t hear extra shrillness in that channel and dropping the floor on the left-channel graph down another 5dB didn’t reveal an equivalent ridge, but it did show up on repeat measurements. There’s also a longer ridge on the right K403 CSD, but that sounded ugly on both channels in that area anyway. All three seem pretty clean in the mid and upper treble (dropping the graph floor for the Senns, which are low from the start in that area).

    PortaPro impedance is interesting.

    Listening impressions

    Listening was done straight out of a phone to a mix of 16/44 FLACs and high-bitrate MP3s (these are cheap portables, after all). In terms of tonal balance, the PortaPros sounded the most natural. The 5k peak is there, adding a bit of excitement, but it doesn’t seem intrusive (not as high as the graph suggests). Soundstage/imaging and dynamics were easily the best of the three. Bass was a bit ‘one-note’, especially when trying to eq it up a bit to try to match the Senns.

    The PX100-IIs had more bass, with lower bass in particular being rendered more precisely than the PPs, and a smooth lower midrange. Attack & decay in bass & lower mids were however slow. Treble to me was too recessed and dynamics in the midrange and treble were reduced, as was detail/resolution (sorry if I’m inappropriately conflating those, but I don’t really get the distinction). Soundstage and imaging were smeared by comparison. Bassheads and fans of a more ‘laid back’ sound might like these, but in direct comparison with the PortaPros and to my tastes, they were unexciting.

    The K403s sounded… er… like they look on the graph. Tonal balance was just off, the wrong-way tilt through the midrange and into the lower treble being very evident. Breathy singers became screechy ones and horns grated terribly. Detail/resolution seemed better than the Senns, but likely because of this overemphasis. Soundstage and imaging were not up to the PP standards. Bass was faster than the Senn but even with eq couldn’t match the Senn down low (maybe surprising given the bigger drivers). Some careful eq tidies up the midrange imbalance somewhat, and there’s detail in the treble; but ultimately the Senn bass goes deeper and the PortaPro has better technicalities across the range.

    Conclusion: PortaPros all the way. Maybe bassheads would appreciate the PX100-IIs outside among background noise, but if technicalities are important they don’t really compare.
     
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  2. Armaegis

    Armaegis Friend

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    Sonically, I prefer the PX-100 over the PortaPros. Comfortwise I still give the nod to the Senn because that stupid hook on the PortaPro catches my ear. But for the price and design, eh, I think Senn was better off with the first version. It was cheaper and had a hard case. You should really take a picture of the Senn with the pads folded flat and the headband clicked together though. It folds up smaller than what you're showing which is an important feature.
     
  3. Biodegraded

    Biodegraded Friend

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    Ah, ok - I see what you mean:

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    Didn't realize they did that (these and the PortaPros are borrowed). It'd certainly make them fit in their pouch better!
     
  4. Ringingears

    Ringingears Honorary BFF

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    I prefer the sound of the KSC-75's with the cheap headband. Cheap version of the Porta-Pro's. And very comfortable. Great for a laid back all day weekend listening session. No critical listening. And forgiving of less than perfect recordings. But still gets the music across.
    Thanks for the measurements @Biodegraded. Was interesting to see what one of my favorites looks like.
    Wish Koss would make a model of the Porta-Pro's with a different headband.
     
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  5. Armaegis

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  6. Biodegraded

    Biodegraded Friend

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    [Lightbulb] OK now I get it; thanks. For proper comparison, the 3 compared fully-folded below. The PortaPros have the smallest footprint but don't go flat:

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    Couple of other things I neglected to mention: the PortaPros and the Senns each come with a carrying pouch, the former in fake leather and the latter in cordura. Cord length on all is approx 4'; Y-format on PortaPros and AKGs, single to the left ear on the Senns.
     
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  7. monacelli

    monacelli Friend

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    Nice work, @Biodegraded! I always like learning about affordable stuff that sounds good. You and @Ringingears have inspired me to put together some KSC-75s with the PE headband. Will be fun to compare with the PortaPro
     
    Last edited: Oct 28, 2017
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  8. riker1384

    riker1384 Acquaintance

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    Any chance of measuring a pair of the KSC-75s with headband? If you were closer I might offer to loan mine, but with you being in Canada the shipping would cost more than the headphones themselves.
     
  9. Biodegraded

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    PortaPro, SportaPro and KSC-75 use the same drivers in what look like the same or very similar housings, so probably sound and measure pretty close (@LSW , whose other results suggest a better measurement rig than mine, has compared Porta and Sporta here).

    But maybe I need to make like @monacelli and put together a pair for my occasional walks home from work. The AKGs will be forever ruined for that purpose now that I've heard the Koss & Senns.

    Edit: Actually from the Koss website pictures it looks like the 35 has the same housing as the Porta (can't tell about the Sporta), and @Ringingears prefers the 75 to the Porta; so yeah, maybe I really do need a pair...

    Edit 2: Yeah, I totally need a pair - just read some more impressions and found them on sale nearby for $14.99 CDN. Headband from a dollar store pair should complete them for measurement.
     
    Last edited: Oct 29, 2017
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  10. Biodegraded

    Biodegraded Friend

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    Here you go, @riker1384

    I couldn’t find anything like the Parts Express headband locally, so I cannibalized a pair of Koss KPH7 (on sale near me for $CAD 6.99). These have different drivers in a non-vented enclosure (yes, I did listen to them first, and no, they’re not about to become the next budget audiophile sensation). Prised off the front plates, dug out the drivers, enlarged the centre holes in the front plates slightly so the 75 clip lugs would fit (5/32” drill bit), then clipped slightly narrower slots horizontally either side to the adjacent holes. Do this iteratively so you don’t make the holes & slots too big; the first one I cut is a bit loose. You also have to remove the plastic guards over the 75s’ contact panels so the lugs will clip in properly.

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    Clipping it all together results in a firm grip on the ears which probably wouldn’t work for big heads, as the housings push the headband out quite a way and the top radius of the band is fairly small too. Wasn’t too bad on my size 7ish skull though, and might relax a bit with use (it did loosen somewhat after time on my measurement head). The disadvantage of this headband is that it won’t collapse or pack flat for travel, but the advantage is that brand loyalty is maintained; everyone can see you’re rocking Koss ;)

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    Consistent differences in frequency response between the 75s and the PortaPros are that the former have a hump at 3 kHz and a peak around 8 kHz. The PortaPro’s relative peak at c. 12 kHz isn’t a consistent difference when looking at both channels of both measurements. The interesting thing – if these measurements are to be believed at all – is distortion in the bass. PortaPro bass distortion is lower and is dominated by third harmonic, 75 is higher and dominated by second.

    I think I heard that; the 75s’ bass sounded stronger but less precise than I remember the PortaPros’ (which are now back with their owner, so I’m going from memory and my scribbled notes). This wasn’t unpleasant; it seemed to me to be between the PortaPro’s and the PX100-II’s, but maybe a bit faster than the latter. The rest of the range was pleasant. Treble seemed maybe a bit better balanced than I recall the PortaPro’s, maybe because of the extra in the 7-9 kHz range. I didn’t notice the 3 k bump as annoying, although it does persist a bit in the CSD plots.

    This headband might make the 75s measure and sound a bit different from the PE one. The tightness would likely have an effect on the bass. Having a solid barrier rather than open space directly behind the vented enclosures perhaps could too, like having rear-ported speakers too near a wall; but that wouldn’t account completely for the distortion differences from the PortaPro - would it?
     
  11. Ringingears

    Ringingears Honorary BFF

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    Thanks for the measurements @Biodegraded! I will leave the interpretation of the measurements to more experienced members. I will say that the 75’s are very finicky with placement on the ears. Takes me a few minutes to get them adjusted for good tonal balance and best bass. The PE headbands although cheap are shit. I ordered three. Good thing. The first one lasted a day. The second is still working, but the right driver falls out sometimes. If anyone is planning on using this set up as a portable rig, look elsewhere. It’s a couch potato rig. Sunday beers, nachos etc. No isolation. But best sound for $16 I’ve heard.
     
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  12. monacelli

    monacelli Friend

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    Many thanks, @Biodegraded. I second what @Ringingears said. Earlier this year I bought some PortaPros on Ebay, and this thread prompted me to pick up some KSC-75s. The PE headband is indeed garbage, but it fits my head better than the PortaPro headband. It's got angular bends in it rather than being perfectly circular, and that seems to fit big noggins better (at least mine). Since I had both, I experimented with switching the drivers back and forth onto each headband. Since the driver housing is slightly fatter on the KSC-75, I found that putting the KSC-75 drivers on the PortaPro headband increased clamping pressure a bit and made them less comfortable. Conversely, the PortaPro housings are really streamlined, so putting them on the PE headband resulted in slightly too little pressure for a good fit. So nothing to be gained there imo.

    So far, I've listened mostly to a rad Elvis record on Tidal that Merrick turned me on to and some Bach. Sound wise, I was surprised that there were some readily identifiable differences (to my ears, anyway). I found the KSC-75s to be a bit more airy, more spacious, with a bit bigger soundstage and more well defined instrument placement. Conversely, I found the PortaPro to be slightly more congested, more closed-in, and somewhat less able to render a convincing 3D sonic image. Subtle differences to be sure. Both of these little headphones have an astronomical performance-to-price ratio. The frequency responses are super close, so obviously they have a very similar tonal balance. I might be full of shit given how close they measure. But they do sound different to me, and I prefer the KSC-75s.

    Given how cheap and how good-sounding the KSC-75/PE headband combo is, I think the PortaPro is a bit overpriced. You're mostly paying for the retro design and heritage of the PortaPro. They are sweet though, so I'm glad to have both. I've got some PX-200 leatherette pads coming for the KSC-75s, so that will be fun to compare them with the stock foam pads.
     
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  13. Biodegraded

    Biodegraded Friend

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    Interesting to read your impressions. I suspected soundstage & imaging were a bit better on the 75s, but no longer having the PortaPros to A/B I wasn't certain so didn't comment. Thanks.

    It did take more fiddling than usual to get left/right bass measurements to match. I don't think the measured closeness of the bass FR relative to the PortaPros is real - the 75s seemed much stronger - but I remain intrigued by the distortion contrasts. My 75 measurements look more like @ultrabike 's of the PortaPros, whereas mine of the PortaPros have lower second-order. Not sure if it's the different SPL/inconsistencies in my system/cosmic rays/the weather/whatever. I too would be interested in input from those more experienced.

    Heh - if you were trying to make them come across as anything less than complete audio perfection, you failed.
     
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  14. Biodegraded

    Biodegraded Friend

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  15. monacelli

    monacelli Friend

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    I received the PX-200 pads a little while ago. Been listening with the KSC-75s for about an hour. So far I'm disappointed. They are undoubtedly nicer looking and more comfortable than the stock pads, but the tradeoffs are too steep. The leatherette pads alter the tonal balance in an undesirable way. First, they noticeably elevate the bass. Second, the thinner foam covering the diaphragm elevates the treble a bit. The thinner foam also makes the mids and highs a bit clearer, which is admittedly nice. I presume this is what motivates people to perform the quarter mod with these 'phones. But in total, the effect of the PX-200 pads is to make the tonal balance more v-shaped, pushing the mids into the background. The PX-200 pads also improve the isolation of the KSC-75s, making them act more like closed cans. Some people might like this, but I don't (more fatiguing). If I were to describe it succinctly, I would say the leatherette pads make the KSC-75s sound more like ATH-M50x's. Obviously not the same, but the change in pads pushes them in that direction. So for my preferences, the PX-200 pads are a downgrade.
     
    Last edited: Nov 4, 2017
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  16. Ringingears

    Ringingears Honorary BFF

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    I think Koss just got it right with the 75’s. Sometimes after spending a day with them, makes me sincerely wonder about all these kilobucks cans out there. Perhaps some price corrections are in order.
     
    Last edited: Nov 4, 2017
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  17. Biodegraded

    Biodegraded Friend

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    Adding Koss KPH30i; might as well keep all the cheap Kosses in one place…

    These are non-collapsible all-plastic on-ears with a 1-button in-line mic/remote, available from the manufacturer and Amazon.com in grey/black or white/blue at $29.99 and occasionally from Massdrop in beige/black at, I think it was $12.99 last time. See those links for pictures.

    Mfr specs 60 ohm, 101 dB (presumably @ 1mW because they’re for sure the same driver as the PortaPro and KSC75).

    Although small, light and sturdy, they don’t fold up or easily come apart for transport like the others in this thread. They have a soft rubber headband and fairly firm but not hard earpads, making them comfortable on the head. Nice cord, too; 4’ long, drapes well, has a nice spring strain-relief on the plug. The driver enclosures/earpads are quite different from the PortaPro and 75 ones, being roughly ear-shaped rather than round on the pad side and conical with slots on the back side.

    The measurements below were made on a borrowed pair of the Massdrop beige ones. Procedure as above; my usual disclaimers apply.

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    FR and impedance compared to the KSC75 (green) and PortaPro (purple):

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    Same drivers for sure. The difference in impedance profile is presumably due to the rather different enclosure of the KPH30i vs the enclosures of the 75s and Portas, which are more similar to each other (but not identical). FR measures broadly similar to the 75s and Portas with the exception of the 4.5k canyons, which on the CSDs turn into ridges. Ridges in the 4-5k area are broader and persist somewhat longer than the other two.

    Bass measures a bit lower, but I heard a more substantial difference there between these and my headbanded 75s. I think this is due to the small round pads of the 75s (and Portas, which from memory also have better bass) fitting into my ears better. Even compensating for the different level, the 75s bass also had better texture; dynamics and detail seemed a bit loose on the 30is. The 75s also seemed higher in level through the upper mids and lower treble, more so than just the small bump at 3k would suggest, and better balanced into the mid and upper treble. It seems to me the 75s have better technicalities through this part of the range as well, but that perception could be due to the FR differences as well as proud-parent syndrome (I remain childishly pleased with myself for how well the 75 earpieces combined with the headband of the $6.99 Kosses).

    The owner of these KPH30is, who also owns the PortaPros measured earlier, says "the Portas have bigger everything - stage, dynamics, detail, etc..." as well as a better FR balance.

    So, for me, in SQ terms: 75s with headband > PortaPro > KPH30i. 30i is the most comfortable, though, has a mic/remote, and is $30.
     
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