solderdude
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Post by solderdude on Jan 15, 2014 21:25:43 GMT
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Rabbit
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Post by Rabbit on Jan 15, 2014 22:10:36 GMT
I'll take a guess and I think that the fake portapros may show a higher level of bass and perhaps a hump in the midbass. It'll be funny if the fake ones are just as good as the real ones. I also suspect that there may not be many real portapros around in the UK to be honest.
I know that I don't trust anyone now after having had three of them from Amazon.
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Post by c61746961 on Jan 16, 2014 20:22:28 GMT
Great work! It would be very interesting if you could showcase the effects (if any) of the kramer mod (http://s7.photobucket.com/user/forumstuff42/media/75mod.jpg.html, www.head-fi.org/t/124243/kramer-mod-ksc75), or maybe measure the PortaPros without the plastic grille, assuming that nothing will get in contact with the diaphragm. To remove it, you have to insert a small, thin object between the baffle and the grille at the positions of the 3 small securing pins and gently lift, being careful to not puncture the diaphragm (your standard, run-of-the-mill serrated kitchen knife worked for me, but I'm guessing a hobby knife or small swiss blade could work as well).
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solderdude
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Post by solderdude on Jan 16, 2014 22:43:39 GMT
I have a single old KSC75 driver (ruined the other one carefully removing a broken wire) I could experiment with that one. Can practice removing the grille on the broken driver Personally I think Koss made the holes the way they are to get the best results... but no harm in trying. That mod is hard to undo though.
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Post by c61746961 on Jan 16, 2014 23:10:04 GMT
I bought 2 pairs of KSC75 to experiment with, but found them so engaging that I ended up giving them as presents :3. I was interested in playing with mass loading the diaphragm (a drop or two of cyanoacrylate over the dome) to try to assess how the ringing would be affected, or maybe some small perforation over the dome. I'm looking forward to getting more pairs to play with, but I reckon I should build a measuring kit first ; )
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solderdude
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Post by solderdude on Jan 17, 2014 6:11:43 GMT
All dynamic headphone membranes start to break-up above 3-5kHz and stiffening won't help but could shift the problem or introduce others. Only ortho headphones do not have this problem but because of larger membranes and being tensioned have other problems but less audible. Making it heavier can also introduce other problems such as roll-off. In the case of Koss it seems they experimented a lot with drivers and also have quite some spread (L-R issues). After all they are made cheaply in China and changes in production materials over the years may also have some influence. I thought the PortaPro that was measured (and is spanking new) did not measure that well compared to the KSC35 (same membrane supposedly). They do sound very similar though (more similar than different) which is more or less backed up by the smoothed comparison FR. The KSC75 is slightly brighter sounding and depending on the source quality/material I prefer the 75 over the 35 in some cases and the other way around in other cases.
a measurement kit is very useful when changing something. Substantial differences, however, can be measured by slightly changing the position of the driver on the rig. This should be taken into account when evaluating/measuring. Averaging or multiple tries and picking out the 'best' measurement is important. Small differences are thus very hard to measure when the headphone is moved in position or repositioned.
In case of the on-ear Koss thingies there is also the pressure that needs to be the same. One way is to lie it down and put a weight on it for instance.
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neo
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Who are you tryin' to get crazy with, ese? Don't you know I'm loco?
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Post by neo on Jan 17, 2014 8:34:02 GMT
Isn't the PortaPro sold by Koss on Amazon?? Seems strange they are fake...I had got a pair from the UK some years back. I still enjoy it
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solderdude
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Post by solderdude on Jan 17, 2014 12:20:42 GMT
It depends from which seller you purchase the PortaPro via Amazon.
The sellers that also sell KSC75 (and/or other models from Koss) are most likely selling the real ones. In general these will be the more expensive ones.
If the seller ONLY sells PortaPro and no other models and has an attractive price you may want to skip that seller, regardless of how much positive feedback they have.
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Rabbit
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Post by Rabbit on Jan 17, 2014 13:59:03 GMT
Neo, can you find the link for the Koss retailer on Amazon? All of the links I see say by 'Koss' but they are fakes!!
The ones I have are fake. Check the numbers on the inside of the arm near the cups. If the number says 4, it may well be a fake. They don't sound awful either.
I've switched the drivers to the KSC ones and there is a marked difference in the bass, Frans. There's less bass I think than there was with the fake Portas. Seems slightly more distant as well, but that may be just me. I'm now wondering whether you get that difference between your 'real' Portas and the KSC?
EDIT: actually, putting the KSC on an amp and coming from a decent source file, they are very good. The presence seems better and the bass is 'cleaner' than my Portapro version. Less muddy perhaps. (I'm going from memory here) The KSC drivers are really very good and I do actually prefer them with the headband since they have more power due to them being pushed onto your ears rather than hanging in there!!
Actually, if the real Portas are similar, then they will be very good. I'd suggest anyone having bought an Amazon Portapro should buy a KSC and do the conversion to the headband. At least it's a real one and not fake and sounds extremely good - way better than the KSC sounds on those ear clips.
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neo
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Who are you tryin' to get crazy with, ese? Don't you know I'm loco?
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Post by neo on Jan 20, 2014 6:30:42 GMT
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solderdude
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Post by solderdude on Jan 20, 2014 8:43:05 GMT
Am not 100% sure if Koss ever made red or any other coloured versions of the PortaPro. I cannot find any info on the Koss website nor pictures of red (or other coloured) PortaPros from Koss so most likely these are fakes. When you google for pictures you see the weirdest coloured 'genuine' PortaPros but not on the Koss site.
Perhaps the clones are fairly reasonable in sound quality as there are not that many people complaining about the SQ.
AFAIK Koss only made the blue ones and the grey anniversary version.
Real PortaPro is quite expensive and limited editions usually are more expensive than the 'normal' ones. These seem cheaper.
If you are looking for a real PortaPro you should contact the official representatives and ask to which stores they supply their wares. If a store sells other Koss models too and the price isn't suspiciously low chances are you are buying the real deal.
I wish postal services weren't that slow...
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solderdude
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Post by solderdude on Jan 20, 2014 8:54:11 GMT
from: www.koreanstown.com/2009/11/warning-fake-porta-pro-discovered/Warning! Fake Porta Pro discovered November 10, 2009 It has come to the attention to Koss that a fake Porta Pro is in production originating in China. The fake Porta Pro has bad packing as well as errors in its prints. The overall design and sound is also inferior to the original. You should take note of all this when purchasing a Porta Pro and buy it only from authorised retailers. Read On to find out more on the difference Fake #. 1: 1 – The Headphone picture on the metalcal does not match ours. Top of headband is all one line on fake one. 2 – Mic screw is a little different on front & back. 3 – Plastic piece that holds the comfortZone label is different. No texture on outside rim. Does not have a ledge under the blue slider. 4 – Plastic piece (earcup w/metalcal ring is different). On inside we have 3 gate circles. Large, med, small. The fake has 3 all the same size. Our 2 top circles are smaller than the fake one. 5 – Metalcal ring is rough looking. Where the ring sits does not have the slope. 6 – The right cup on the fake has a cavity no. but it is no. 4 dull. The Koss phone has a no. 1 but shiny where the no. is. 7 – The “KOSS” embossed on the plug is not very deep as on ours. Also does not have a trash can label on cord. 8 – The impedance reads 30 to 33.7 ohms as where Koss reads between 60 to 63.4 ohms. (Personally I think this is the most obvious indicator)9 – Element cups, terminal board covers & grille plates are different. 10 – Cushions are a little larger & a slight difference in color. Do not have the crease on top like ours. Packaging: 1 – Different backcards. 2 – Inner tray does not have the indents where the headband lays. 3 – Green color is not the same on top insert. 4 – Carrying pouch is different than Koss. Lines are in where “KOSS” is embossed. 5 – Headphone is loaded backwards in tray.
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Rabbit
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Post by Rabbit on Jan 20, 2014 11:56:52 GMT
Frans, I think the Amazon ones come in blister packs, not the packaging that you sent me in your email. You have to cut them out of the packaging. Also the plugs on mine are not angled, they're straight.
I have contacted Amazon about this but they don't reply,
They don't sound too bad which is why no one has said anything I guess.
What is bad on the Amazon site is that they say Portapro by Koss which is a blatant lie if they are copies.
In that case, I guess that most in the UK haven't heard a real Portapro. I'm really Interested in how my version measures against the one you got for me. My guess is that they are close.
However, I really like the KSC75 on the Porta band. If the Portro is like these I'll be really happy with them!!
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solderdude
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Post by solderdude on Jan 20, 2014 12:29:22 GMT
The PortaPro/KSC35 has slightly less treble energy compared to the KSC75. Slightly calmer/warmer sounding.
If you have a multimeter you can check if they are fakes or not, assuming all fakes have about 32 Ohm drivers and real ones 60 Ohm
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Post by c61746961 on Jan 20, 2014 16:32:46 GMT
I ordered a pair of PortaPro from Amazon (sold by) on last year's black friday and received the ones with the new black packaging and a more robust 45 degree plug, they seem by all accounts legit, except that the structural pieces now have the markings '2' and '3' instead of '1', and there's no 1/4" adapter to speak of. They sound exactly like the pair Frans recently measured, 5 KHz peak and all.
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