At first, I was using DACT attenuator which was given to me by my audiophile friend in Japan after he purchased Weiss ATT202 passive attenuator. Later on, I decided to change to a stepped shunt attenuator as this was the type used in higher level Audio Note UK finished products. The attenuator I installed was based on the 23 step attenuator kit from K & K Audio (http://www.kandkaudio.com/linestage.html) assembled by “the discerning ear” (http://www.thediscerningear.com/). The K&K audio’s kit comprises of a 2-pole, 23 position Seiden switch and PC boards that will accommodate standard through-hole leaded resistors. The kit does not come with resistors to allow a buyer to choose one’s favorite. I used AN UK ½ W tantalum for load / “series” resistors and Takman REX (carbon film) for shunt resistors. Use of the PC board in this kit seems to makes the assembly much easier but some may argue the trade-off of lengthening the signal paths.
Changes to the sound from the new attenuator were notable but not as significant as I had anticipated. It was rather difficult for me to decide whether I liked the change or not. DACT sounded punchier with forward mid frequency range (in a good way that added more depth to the sound stage) with lots of air and details. On the other hand, shunt attenuator was gentler and smoother with bit less details but musical if bit euphonic.
Vishay VAR-Series "naked" Z-Foil
Few months later, I read this article in Dick Olser's "Audio Mecca / Black Dahlia" website. After some thinking and deliberations, I decided to change the load/”series” attenuator to a different one. The pair of resistors I chose was Vishay VAR-Series "naked" Z-Foil resistor which is also sold under the product names of Texas Components TX2575 or Charcroft Electronics CAR Series. This was another part that I heard a lot about even before reading the article and have been curious to try.
I was very surprised that one resistor in each signal path can make such a profound and effective changes to the sound quality. Changes were not overemphasized but clearly recognizable in the way that no particular aspects of the sound had dramatic differences but elevated every attribute of sound quality by a notch bringing the overall sound of the system up to the next level. Sound became more transparent, detailed, improved sound stage and sound image, more tunefull and deeper bass with excellent pacing. Most pleasantly, my system did not sound analytical or sterile. It gained a well established balance between neutrality and musicality. Human voice and acoustic instruments sounded more natural without being too warm or veiled. With the Vishay VAR-Series "naked" Z-Foil resistors (Z-Foils) everything sounded more realistic. The only drawback would be that the faults of recordings can be heard more clearly but only to the point that music remains enjoyable in most cases. In spite of perceived impression on improved high frequency extension, the sound was never bright and I did not feel any increased level of listening fatigue after hours of playing music with these new resistors.
Another very expensive part as far as resistors are concerned but in the context of this hobby, I think this is one of the most cost effective upgrades one can install in the system as long as it is installed strategically in most critical location.
11th June 2013