[julian67]

An iPhone drives the 75's with +47 ohms just fine. No AV, stereo receiver or even portable amp is necessary.

I'm not going to bother DBT over $50. Sorry if this is not credible enough. The headband, resin coated housings and pads make the majority of the difference. Impedance gives different flavors, its not a necessity but the deep bass does sound better to my ears, real or imagined, that's all that matters but with sweeps and tones I've heard 40hz at decent volume compared to 60 and above. I'm also sure there is variance in a product so cheap.

Here is an easy way to add custom amounts of impedance: http://item.mobileweb.ebay.com/viewitem?itemId=290372905689

I didn't suggest double blind test, only that an ordinary blind test would be useful and credible. In a case like this a blind test is as easy as the subject closing their eyes while their friend places the headphones on their ears and notes their impressions on playback. I'm not trying to put anyone on the defensive or tarnish their pleasure and am happy to start with the assumption of goodwill in and by all parties. I'm not one of those people who assumes malice or dishonesty and/or tries to berate people into silence by having a bunch of people arrive and shout insults while claiming the uniform nature of rent-a-mouth nastiness to be evidence of objectivity

It would actually be interesting if someone could do such a direct comparison, especially one that doesn't rely on trying to remember what the unmodded phones sounded like a few weeks ago as this is intrinsically too flawed to be meaningful.

I have the headband and found the sound difference is actually about position, not clamping force (a bit of bending and the clips can have the same clamping force as the headband).

My understanding is that iPhone output impedance is below 5 ohm so the impedance mod is probably superfluous. The iPhone would drive the KSC75 equally well before modding as after.

 

[shotgunshane]

I have 2 stock pairs (with clips), 1 modded pair without added impedance and 1 modded pair with 47 ohms added. They all sound different and will eventually be gifts when I'm through playing.

The +47 ohm version sound differs from the regular modded version as follows:

They have more air without the 47ohms and at first I thought that would be a deal breaker. But the the +47 still retain good sparkle. I also think the +47ohms smooths the very slight upper mid shout they can have without. But the biggest surprise is how good the lower mid bass and deeper bass sound. It's a little more present and just sounds really good- musical, textured and fun.

Here are my notes on the differences of the modded pair without impedance differs from stock (with clips):

Bass is fuller but firmer than stock. Most importantly the lower mids are richer. Vocals sound much better. It's gone from being a pleasant sounding budget clip on, to a very nice, musical sounding headphone. My wife, who couldnt give a care about my hobby, definitely wants a pair modded for her. Tonally, they are richer, more natural sounding with improved instrument realism.

 

[JoeDoe]

It would actually be interesting if someone could do such a direct comparison, especially one that doesn't rely on trying to remember what the unmodded phones sounded like a few weeks ago as this is intrinsically too flawed to be meaningful.

I have the headband and found the sound difference is actually about position, not clamping force (a bit of bending and the clips can have the same clamping force as the headband).

My understanding is that iPhone output impedance is below 5 ohm so the impedance mod is probably superfluous. The iPhone would drive the KSC75 equally well before modding as after.

Just for the record, my comparison was a side by side, I picked up two pairs originally during the Office Depot deal.

And I certainly agree regarding how positioning affects the sound. The centered pads are made or broke by their positioning, much more so than the unmodded ones.

 

[189906]

XPrime, Check if theres any hair or something else on the back of them. I've had bass problems cause of my hair ending up on the back of them.
 

 

[HiFlight]

.................................................................snip.....................................................................
My understanding is that iPhone output impedance is below 5 ohm so the impedance mod is probably superfluous. The iPhone would drive the KSC75 equally well before modding as after.

The added impedance is an inexpensive option that one can either select or not. FWIW, I have never found a source that cannot easily drive the Koss to a very high volume level even with the 47 ohm option added.

 

[julian67]

....one can either select or not. FWIW, I have never found a source that cannot easily drive the Koss to a very high volume level even with the 47 ohm option added.

Thanks for the info. I hadn't seen any mention of it being selectable.

As for sources which don't drive the KSC75 easily the Sansa Clip+ is an obvious one. I have a Clip+ and it really struggles with the KSC75s. This is masked by modern pop/rock tracks which are almost uniformly extremely loud, but with recordings with wide dynamic range there is no escaping the fact that this device isn't up to driving these headphones. With a non/pre loudness war recording the Clip+ with KSC75 at maximum volume isn't very loud, has fairly feeble bass and responds to extra bass added with eq by distorting.

For example I've got my KSC75 on now, attached to my Clip+. It's at max volume playing a choral piece and volume is not even close to anything natural. For illustration here's a waveform and spectrogram of the file:




This is a lot better with my iRiver players which are about a third more powerful and, of course, is not a problem with home audio.

 

[palmfish]

My PX200 pads arrived today. Genuine Sennheiser pleather version.
 
The KSC75 sounds like crap with them on. Muddy and bloated. Treble disappears. Surprisingly, I also had to turn the volume down 4 clicks compared to the stock pads. I'm guessing they seal the driver chamber better around the rim of the earphone or maybe it's a tighter seal over the ear creating a resonant cavity or something. I don't know.
 
Whatever it is - don't bother with them.

 

[HiFlight]

Thanks for the info. I hadn't seen any mention of it being selectable.

As for sources which don't drive the KSC75 easily the Sansa Clip+ is an obvious one. I have a Clip+ and it really struggles with the KSC75s. This is masked by modern pop/rock tracks which are almost uniformly extremely loud, but with recordings with wide dynamic range there is no escaping the fact that this device isn't up to driving these headphones. With a non/pre loudness war recording the Clip+ with KSC75 at maximum volume isn't very loud, has fairly feeble bass and responds to extra bass added with eq by distorting.

For example I've got my KSC75 on now, attached to my Clip+. It's at max volume playing a choral piece and volume is not even close to anything natural. For illustration here's a waveform and spectrogram of the file:




This is a lot better with my iRiver players which are about a third more powerful and, of course, is not a problem with home audio.

Not having ever owned a Clip, based on the following specs from Sansa (below) it sounds like without external amplification, it was designed primariliy for use with IEM's rather than on-ear phones. Given their impedance specs, even a stock PortaPro or KSC-75 doesn't make the cut. One should also keep in mind that to double the volume level requires 10x the power + headroom reserve for transients. 9mw/ch at only 16 ohms is not much power to play with. Clearly, a KSC-75 with (or even without) the impedance mod is not the phone of choice for an unamplified Clip!

"Thanks for emailing SanDisk Technical Support. It is our goal to make sure you have all the resources you need to get the most from your product.

Here is the information your requested:

Specification of maximum output power for Sansa Clip+ as well as Clip and Fuze (File playback) is 18mW +-1mW @16Ohm load. Impedance range is 16-32 ohms."

 

[julian67]

Not having ever owned a Clip, based on the following specs from Sansa (below) it sounds like without external amplification, it was designed primariliy for use with IEM's rather than on-ear phones. Given their impedance specs, even a stock PortaPro or KSC-75 doesn't make the cut.

This is true. None of these 60 ohm Koss headphones are actually a very good match for any of the Sansa Clip/Clip+/Fuze/Fuze+ series players. Also true is that the Sansa players are hardly unusual in their meagre power output. For example the iPod Touch 3G has even less power.

I've owned and used a few players, phones and tablets (Nokia, Archos, various others) which are even noticeably less powerful than the Clip+. They aren't unusual. My iRiver H140 and H340 players from 2003 and 2005 were supplied with 32 ohm impedance buds and ouput 12 mW per channel into 32 ohm or 20 mW into 16 ohms and are more powerful than lots of more modern players. The one piece of personal audio kit I still have from the same era as the Koss drivers is my Sony WM-D6C Professional Walkman. It ouputs 30mW per channel into 32 ohms. Next to a Sansa and most current players this makes it a red clawed monster

So I think the resistor mod for the Koss is not a great idea if they are to be used with modern portables because the Koss drivers are already not sensitive enough to work that well and it seems their deficiency in this area is masked only by the fashion for very loud mastering.

 

[palmfish]

This is true. None of these 60 ohm Koss headphones are actually a very good match for any of the Sansa Clip/Clip+/Fuze/Fuze+ series players. Also true is that the Sansa players are hardly unusual in their meagre power output. For example the iPod Touch 3G has even less power.

So I think the resistor mod for the Koss is not a great idea if they are to be used with modern portables because the Koss drivers are already not sensitive enough to work that well and it seems their deficiency in this area is masked only by the fashion for very loud mastering.

The KSC75 is rated at 101 dB / mW - which means it is a sensitive, easy to drive earphone. If the 18 mW @ 16 ohm rating for the Sansa Cip is accurate, then even a pessimistic rating of 9 mW @ 60 ohms is more than ample power to drive the KSC75 to earsplitting volumes without clipping.

I have mine plugged into my Clip as I type this listening to Respighi's "Ancient Aires and Dances - Suite No. 1" (Neville Mariner - Los Angeles Chamber Orchestra - EMI 1976) and I cannot listen at max volume without discomfort. Im at 90% volume which confirms they arent as loud as my IEMs, but this has more to do with the open and non-sealed design, not efficiency (confirmed by my experiment earlier with the PX200 pads which make them much louder with the same volume setting - I cannot go above 75% volume on my Clip with the Sennheiser pads installed).

 

[HiFlight]

Please keep in mind that the Koss mods, including the increased impedance, were originally developed for use with the Tera-Player which plays, according to Charles, 5x louder than an iPod. Having never owned an iPod, I can't make any comparisons, but if one feels that additional impedance is not appropriate for the intended use, by all means do not add it.

 

[julian67]

The KSC75 is rated at 101 dB / mW - which means it is a sensitive, easy to drive earphone. If the 18 mW @ 16 ohm rating for the Sansa Cip is accurate, then even a pessimistic rating of 9 mW @ 60 ohms is more than ample power to drive the KSC75 to earsplitting volumes without clipping.

I have mine plugged into my Clip as I type this listening to Respighi's "Ancient Aires and Dances - Suite No. 1" (Neville Mariner - Los Angeles Chamber Orchestra - EMI 1976) and I cannot listen at max volume without discomfort. Im at 90% volume which confirms they arent as loud as my IEMs, but this has more to do with the open and non-sealed design, not efficiency (confirmed by my experiment earlier with the PX200 pads which make them much louder with the same volume setting - I cannot go above 75% volume on my Clip with the Sennheiser pads installed).

Well several of Respighi's orchestral works are famously, fantastically, enjoyably and phenomenally L O U D They must be be amongst the biggest, brashest, loudest pieces composed for a modern orchestra. I don't have that version but I do have a CD of the same work performed by l'Orchestre de Chambre de Lausanne under López-Cobos, and several other works by Respighi besides. I have to admit I didn't do any measurements but I suspect if I sorted my >450 classical and baroque CDs in order of loudness I would be very surprised if Respighi didn't feature several times in the top 10. Subjectively I think the loudest classical CD I have is Rachmaninov's Symphonic Dances and Isle of the Dead performed by the RPO under Enrique Batiz, and the next loudest is Respighi's Symphonic Poems performed by....the RPO under Enrique Batiz! They are easily listenable at max volume on the Clip+ with Koss KSC75. With earphones of lower impedance and higher sensitivity max volume is unbearable and probably would cause hearing damage.

I have some other earphones:

Shure SE215:
Sensitivity (1 kHz): 107 dB SPL/mW and Impedance: (1 kHz): 20 Ω

Sennheiser CX95:
Sensitivity (1 kHz): 117 dB SPL/mW and Impedance: (1 kHz): 16 Ω

Both those are much more typical of modern portable 'phones and unlike the Koss they fall well within Sansa's recommendations. It is not a small difference between 101 dB and 107db, while from 101dB to 117 dB is actually an enormous difference.

Right now I have playing on my Clip+ Respighi's Symphonic Poems (RPO/Batiz) at max volume with no Eq, no replay gain, no crossfeed or any other manipulation of the audio and it is not even disturbingly loud. I could easily listen louder. I briefly swapped the Koss for my Shures and hit the pause button after less than a second because it was ASTONISHINGLY AND TERRIFYINGLY LOUD!!!!! at the same unchanged settings. I would not even dare to do the same with my Senn CX 95s because it would probably damage both my ears and the IEMs.

I'm sorry but there is no way that the Koss KSC75 can be said to be easily driven by the Clip+. You can achieve only moderately high levels. Bass response is notably unimpressive and the overall sound quality doesn't approach that of more powerful players or amps. It's well known that these Koss earphones really scale with amplification and that isn't just hearsay, experience bears it out.

 

[julian67]

....If the 18 mW @ 16 ohm rating for the Sansa Cip is accurate...

It isn't.

Real measured output according to nwavguy is "about 15 mW into 16 ohms (or 7.5 mW into 32 ohms)".

He thinks this is pretty good (I never did work out why, except he likes to say nice things about it) but now please recall that my old Professional Walkman outputs 30mW per channel into 32 ohms and my iRivers output 20 mW into 16 ohms. The iRiver is about a third more powerful and the Walkman (from the same era as the Koss drivers) vs the Clip+ is like an IED next to an indoor firework.

 

[jmoore914]

I've been using PX100 pads on my KSCs for a while now and today decided to try the stock pads for fun. Wow, I have no idea why I switched from the stock pads. They are wayyy more comfortable (PX100s clamp too hard) and sound a little bit better I think. Sound quality change isn't too noticeable and I would probably stick with the PX100 pads if they were more comfortable than stock (they also look cooler) but they just aren't. So if anybody is thinking of switching pads, don't bother.

 

[palmfish]

It isn't.

Real measured output according to nwavguy is "about 15 mW into 16 ohms (or 7.5 mW into 32 ohms)".

He thinks this is pretty good (I never did work out why, except he likes to say nice things about it) but now please recall that my old Professional Walkman outputs 30mW per channel into 32 ohms and my iRivers output 20 mW into 16 ohms. The iRiver is about a third more powerful and the Walkman (from the same era as the Koss drivers) vs the Clip+ is like an IED next to an indoor firework.

Im sure thats all true, but my point is that the KSC75 has a rated sensitivity of 101 dB/mW. Thats louder than anyone should listen for more than a handful of minutes at a time. So even if we worse case the Clip at 3 or 4 mW its still way more than is needed to drive the KSC75.