PX-560 impedance matching

[Jokeyman123]

I've already posted some info about this in other topics here, but I thought it might be helpful in general, and this topic might also apply to the other PX Privias, including the PX5s which I do not have. Administrators if you think this topic should be posted elsewhere, feel free.

 

First, to measure the true "impedance" of a headphone or audio output jack requires some complex math and circuit testing-it is not a simple resistance measurement as done with a multimeter. I'm stating this as it is important to understand the difference when connecting headphones, amps and recorders.  When measuring the headphone jack resistance I will get 4 ohms but this is not the impedance measurement, it is a passive measurement of whatever components are connected to the headphone jack circuit (which by the way contains some coils among other things, which again are rated as a "reactive' device, not a simple resistor).

 

Why post all this? If anybody thinks their Privia doesn't sound too good with headphones, be careful what you are using.

 

I discovered through trial and error that some of the newer lower impedance headphones do not sound very good with the Privias, even though the fidelity through my mp3 , computer and stereo equipment sound fine. Specifically my newer AKG52 with an impedance of 52 ohms sound muddy and like a cheap set of earbuds, but are fine through all my other sources. Since many of the newer headsets are being designed with lower impedances-for example the older AKG K240 used 600 ohms impedance, the newer Chinese ones are 52 ohms, the newer K72 and 92 are 32 ohms I recall. I don't have the 72 or 92 or any of the other Beyer or other pro lines. I do have a pair of older AKG K300 and K301s, monitor cans for the studio and since these I'm guessing are closer to the impedance of my Privias, bring out the tonal qualities of the Casio pianos mkuch better, including loops, artifacts and other musical incongruities-not that there's anything wrong with that! 

 

So if anybody wishes to post some of their listening results with different headsets with your Privia (or other Casio WK or CTK for example), it might help some others here avoid some of the difficulties new users may experience, thinking there is something wrong with their Casios. One other thing-I've also tested my Privias with various earbuds-again most sound muffled and usable but certainly not the quality these instruments are capable of-again most earbuds are very low impedance, apparently this seems to affect the quality of the sound output. I don't own any, but i would guess some of the higher impedance earbuds might sound quite different. I have one set of "higher end" Koss earbuds which do sound somewhat better. I do not have all the necessary equipment to measure impedances under a "live" load, I can't get accurate measurements from any of this equipment.  I can only guess and go by specs provided. Notice the PX560 manual does not provide the impedance rating for the headphone jack as do some other manuals, but does provide for the line in and out jacks. Since these are rated in the thousands, given equal output voltage at thesejacks compared to the phones jack, this is why headphones plugged into the line out will demonstrate only a very weak audible sound. I'm sure many of you here already know all this, but again for those who are just getting their chops......

 

Hope this helps. as always    BACK TO WORK......

 

[Casiokid]

From reading other keyboard blogs 'monitor' type headphones is the way to go -not hi-fi headphones .  It would seem some connoisseurs, here in the UK, seem to favour the Grado SR 60 series of headphones for this purpose,  Like you Jokeyman123 i'm learning about these things too! 

 

This impedance matching also applies to choice of external amps and the use of DI Boxes which can be another mystical 'black art.'

[Jokeyman123]

I'm having no trouble with line in and out impedance with my amps and recorders, these are well-defined in the specs. I am trying an experiment to change the resistance of my headphones with a simple resistor circuit-to see if this factor alone will change how my K52s respond to the the Privias-thinking that if i increase their resistance although making these less efficient, will change the frequency response and clean up the sound. This would also work with cheaper earbuds theoretically.  I'll post my results when I've tried it.

[KevinD]

Jokeyman123 - thanks for the OHM resistance data. Privia PX-560 with Sony MDR-V6 Studio Monitor headphone sounds good to me. Some do not care for the headphone sound, first released in 1985, 63-ohm impedance at 1kHz, 40mm drivers, no noise cancelling. Sweat causes ear pad cover flaking after 3 - 4 years so I buy a $10.00 - $20.00 replacement ear pad cover.