Portaphile NOK aka “Nude Overkill”

I thought it’d be a good time to release a bit more information on the Portaphile NOK.  The Portaphile NOK will be based on the three channel amplifier architecture found on the 627 line of amplifiers.   It will have three OPA627BM followed by six LME49600 buffers, two per channel.  The OPA627BM is the higher performance “Can” version of TI’s already excellent OPA627.  I’ve been using these opamps in a special edition Shohin with excellent results and decided to base our upcoming flagship amplifier around this excellent opamp.  Other upgraded components include the use of Vishay “Naked” Z-Foil resistors in the amplifier section and also in the custom two stage stepped attenuator.  These resistors are considered to be the best resistors on the planet for audio.   Vishay “Naked” Z-Foil series are also known as Texas Components TX2575 and Charcroft Electronics “CAR” series.  This is where the “Nude” comes from in Nude OverKill.   If you haven’t heard of these resistors, Google Naked Z-Foil review to get an idea of their potential.  Some reviews online even show benefits after just replacing ONE resistor with a Z-Foil.  They are near perfection when it comes to a resistor for audio.

Another design change in the upcoming NOK is the removal of the input potentiometer.   Whether it’s a digital pot or a carbon based potentiometer, all potentiometers have some affect on the audio transfer from your source and almost always that affect is negative.  What I’ve decided to do with the NOK was to just get rid of it alltogether and design a two position stepped attenuator using two Vishay “Naked” Z-Foil resistors per channel.   The two resistors will provide two fixed user selectable volume settings and your main volume adjustments will be controlled by your source.   This will the first “true” portable headphone amplifier when taking into consideration that typical audio amplifiers for speakers don’t have any volume control.  All they do is provide amplification which is what the NOK will do.

The case for the NOK  will be machined in house out of a one inch block of aluminum and that is what is giving me greatest delay at the moment.  The size of the amplifier is about the size as the Chord Hugo although a bit taller to accommodate the battery.  I was reluctant on giving away to much information until I had a final product but my plan is to get the amplifier out in a few more months.  Anyone interested in pre-ordering please send me an email.  I am expecting the final price to be 999.00 and I will offer a discount to anyone wanting to pre-order with the anticipation of there being about a three month wait period before shipping.    Thanks again and happy listening!

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