Compare Series, Ladder, and Shunt Type Stepped Attenuators
In 1995 Goldpoint Level Controls began offering Ladder type stepped attenuators to audiophiles worldwide. And in 1998 we added the Shunt and Series type stepped attenuators.
But in 2003 we ceased building "Ladders" and "Shunts" because we found a way to make
stepped attenuators which had all of the audiophile positive attributes and none of the negatives. This entailed building Series type stepped attenuators using truly transparent sounding precision resistors. These specially selected resistors are thin film nichrome SMD type, laser trimmed to 0.5% tolerance. We now use them on all of our standard V24 and V47 stepped attenuators.


Series Type Stepped Attenuators
As its name implies, the series type stepped attenuator is simply a series of resistors forming one "long" voltage divider. The rotary switch is used to select where, in this voltage divider, the output will be. Electrically, it is just like a potentiometer with built-in mechanical detents.
Like a potentiometer, the input impedance of a series type stepped attenuator remains constant, so the signal source always sees a constant, non varying load.
advantages:
Only one switch contact in the signal path.
Fewer parts and lower cost than Ladder type.
No "pops" or "clicks".
Easier to use - emulates potentiometers.
-Ladder Type Stepped Attenuators
In a ladder type stepped attenuator, the rotary switch is used to select an input-to-output resistor and an output-to-ground resistor, forming a set voltage divider for each switch position.


The total series resistance of each two resistor set is equal, so the signal source always sees the same impedance. Ladder type stepped attenuators minimize the effects of using less precise or noisy resistors.
Two switch contacts in signal path.
Often causes “pops” or “clicks" while turning knob.
Twice as many resistors required (compared to series & shunt types).
Requires higher cost switches with twice as many wafers.
-Shunt Type Stepped Attenuators
In a shunt type stepped attenuator, a voltage divider is formed with one “constant value” input-to-output resistor, and one other resistor selected by the rotary switch position.


Although behaving just like a ladder attenuator for each switch position, shunt attenuators vary the impedance as seen by the signal source. To minimize this, one wants to choose a large value input-to-output resistor. This can conflict with the need to have a small input-to-output resistor so that the attenuator will pass the maximum signal level at high volume settings (and have less effect on high frequency signals).

This type of attenuator is best used with low impedance signal sources, thereby minimizing the effects of the attenuator’s own varying input impedance and allowing a smaller value for the input-to-output resistor.
Generally great sound because fewer resistors are used in each position
Only one switch contact in it's signal path.
Fewer parts (lower cost) compared to ladder type.
Varying input impedance requires careful considersation of the actual
      circuit or gear it will be used in - so as to avoid impedance mis-matches with
      the signal source output .
-An Expanded Chronology of Resistor Types used in Goldpoint Stepped Attenuators:
In 1995, Goldpoint Level Controls began offering Ladder type stepped attenuators world-wide over the then fairly new internet. The company had sprung into existence due to the high demand for these stepped attenuators - which had spread by word-of-mouth from a very successful "monthy project" in a vacuum tube enthusiast club in San Francisco.
Over the next 7 years we added Shunt and the Series type stepped attenuatoprs to our product offerings. Back then it was considered that both Ladders and Shunts generally had better sound. But Ladders were twice as expensive due to needing twice as many resistors, switch contacts and wafers - and can produce pops/clicks while turning them up/down. And Shunts can do strange things to the sound with impedance changes when turning them up/down.
Most of the resistors used throughout the audio industry are inexpensive 5% tolerance carbon type, or at most 1%, thick film Ruthenium metal film type. Pre 2003, when you wanted the best sounding Goldpoint stepped attenuators we could offer - and could pay for it - we used Vishay bulk foil, Audio Note Tantalum, or IRC Nickel-Chromium (Nichrome) metal film resistors to provide even better clarity than our standard (excellent) German made Roederstein resistors (Ruthenium but great sounding). Back then we spent hours and hours daily talking with audio enthusiast customers about many different resistor types and brands and their varying sound qualities, including carbon resistor types.
In 2003 we discovered why people had been raving about the KOA resistor brand we occasionally employed. These were fairly inexpensive, but turned out to be mostly Nichrome metal film - and that's why people raved about their sound qualities so much. Then we found out that the Dale RN55/RN60 resistors are Nichrome too, which we used exclusively for a few years after the Roedersteins became hard to get. Lastly, in 2003 that we found out that the expensive (over $1 each back then) IRC 0.1% tolerance RC55 resistors are also Nichrome type - and these had the best sound qualities we could identify amongst all resistor types - period.
What happened in 2003 is that we started using precision Nichrome SMD resistors on all of our stepped attenuator types: Series, Ladders, and Shunts. And then we found that we really could no longer easily tell the difference between the sound qualities of our own Series, Ladders and Shunts. This turned out to be due to the new SMD Nichrome resistors we were using. And so we dropped the Ladders and Shunts from our offerings, along with their inherent problems. The precision SMD Nichromes are so transparent sounding, we decided why use anything else - because even the Series type stepped attenuators were totally transparent sounding - the best of all worlds for price, reliability and overall performance, including unassailable sound quality.
Now we primarily recommend Nichrome thru-hole resistors to our customers when building their own custom stepped attenuators onto our Goldpoint V24C or V47C blank boards. see at: https://goldpt.com/r_series.html

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