[Moonwalker]

Hi!

Yesterday I purchased used pair of Koss Porta Pro phones. They have the gold, not the nickel jack as termination. I think that means they were made in China, not in the USA. I paid about 20$ for them (750Kc,-). They have unknown past, but I think they were used for about an year, the pads were a bit worn. I changed them for new ones, for hygienic reasons. I cleaned the old pads in water with mild detergent and will be using them as spare ones. I removed the driver part from the headband and cleaned the headband in pure alcohol. (They smelled like old cigar)
Then I put everything back in place.

I tested them against my rarely used Porta Pro (they have about 15 hours playing on them). The used pair sounds more relaxed, a bit more detailed, and has less highs (tested by sweep tones), but to my ears, they are much more musical. I start tapping my feet almost immediately and even sing along!

There's surely some difference in the sound the two pairs produce. I think the previous user played them pretty loud (as I can hear manytimes in bus etc...) and the diaphragms are now free from the tension and stress. This is just my thought and my observation.

Your
Moonwalker

 

[blr]

Thanks for the info.
Are you going to try to break in your new pair and then compare them again? If the two sound the same after extensive break in of the newer pair this will be a strong point in defence of the break in hypothesis. Otherwize the difference in sound may just be due to bad QC or the fact that they were made in different factories.

 

[Moonwalker]

Hi, blr!

Yes, I would use the second pair too, so someday I'll put them in comparison. But I think it'll take more than a month to really burn-in them to the same level as the other ones, and I don't want leave them connected and playing all nights and days without interrupting. I'll be just using them normally and post if the two will come closer (be identical?) in sound.

Happy to see some interest about CHEAP

Koss.

Your
Moonwalker

 

[Nezer]

Last night I took some KSC-50s and ran it into a 120 Ohm adapter (that shipped with the Porta Corda) and ran THAT into the 120 ohm output on my Corda HA-1.

Why did I do this? I'm still burning in the power caps I replaced and wanted some load on the Corda. This gives me about 300 Ohms which is about the same load as HD600s.

Anyway, when I listened to this configuration... Wow... Those things sound amazingly close the the HD600s! Not *quite* as detailed, but I would say easily 95% of the HD600s for practically none of the price.

These little 60-ohm Koss cheapies continue to amaze me! 95% of the HD600s and I can throw them in my pocket.

 

[bkelly]

If the truth were told the Porta-Pros do some things better than the HD600.

 

[andrzejpw]

lol, I know. whenever I put on ksc-35s, I just ask myself, "HOW MUCH?"

 

[Moonwalker]

Hi!

Well I attached a .png picture showing differences between my 2 Porta Pros. The upper is sweep tone response of the used, cheap purchased pair with golden jack, the lower one shows response of the barely used Portas made in USA.

Look and decide if it's just bad QC or real burn-in effect.

I don't know yet...

Your
Moonwalker

 

[blr]

Now, that's interesting.
For the first time, as far as I know some possible burn in effect has been quantified. From what I could see the broken in pair has a bit smoother upper midrange and perhaps a bit more bass (did I read the graphs correctly?) which is exactly what people usually percieve after burn-in.
Good work Moonwalker thanks a lot.

 

[Moonwalker]

Hi, blr!

Yes, you're right!

The large peak on lower graph around 40 sec. point means 5400 Hz, the second one at 46.5 sec is about 12000 Hz. Also, the upper graph shows (maybe not so clearly) the lower bass begins much deeper (for me, I can hear thumping bass at 16-17 Hz on broken-in pair, around 21 Hz on new one) and the bass hump around 11 sec. point is lower (better) on broken-in pair.

Thanx for interest and your reply!

Your
Moonwalker