Goldpoint SA1X and SA2X passive attenuator technical measurements Standard Prologue If you are unfamiliar with audio measurements please use a search engine with the query: "audio measurements" or "audio measurement handbook" Look for publications by Richard C. Cabot and also by Bob Metzler, both from Audio Precision. There are other useful publications as well. These will provide basic knowledge. Interpretation of the following measurements is beyond the scope of this post. The data presented were collected as follows: 1. PrismSound dScope III, picoscope 5243B, Atten ATF-20B signal generator, Keysight 34465A DMM 2. Balanced cables Canare L-4E6S starquad and Belden 1800F with Neutrik XLR connectors 3. Single Ended cables Audioblast HQ-1 1.5 ft with Rean RCA connectors or RG6 with BNC connectors 4. 75R RCA to BNC adapters as necessary 5. Vaunix Lab Brick USB hub for measurement equipment 6. Audioquest Forest and Schiit Pyst USB cables used for measurement equipment 7. 14 and 16 AWG sheilded power cables used All testing performed at 0 dBu input and 30 dB attenuation unless otherwise noted. Highlights It should be no surprise the internet abounds with armchair engineers spewing incredible quantities of misleading bovine excrement. This measurement set will hopefully offer some enlightenment. A passive attenuator is simply a potentiometer or stepped attenuator forming a resistor divider to reduce the input signal by some desired amount. Several passive attenuator myths will be addressed: 1. reduces audio band frequency response 2. reduces audio transient response 3. increases distortion 4. reduces dynamic range 5. increases noise 6. introduces channel imbalance - this is matter of cost / performance tradeoff. Low cost potentiometers can introduce channel imbalances especially at greatest attenuation (lowest volume settings.) Well designed potentiometers and stepped attenuators will not have this issue. Picture of the Audio Lab setup for Goldpoint SA1X and SA2X measurements Passive Attenuator part 1 of 3 SA1X amplitude - phase - gain (A01) 100K load From this measurement it appears a well designed passive attenuator achieves less than approximately 0.005 dB channel imbalance. Myth #6 busted for well designed potentiometers and stepped attenuators (read: not cheap.) SA1X THD+N THD nth harmonic distortion (A04) FFT 0dBu + 30dBu attenuation 100K load Y axis range has been lowered to include -140 dBu in the FFT. Distortion measurements demonstrate exceedingly low distortion, at the same level as that of interconnecting wire. Myth #3 busted. SA2X signal to noise (A07) 100K load Signal to Noise is also at the same level as interconnecting wire. Myth #4 busted. SA2X Crosstalk (A08 A09) 100K load Two cables run parallel will exhibit approximately the same level of crosstalk. This again is exceedingly low. SA1X 1 KHz spectrum Left and Right 0dBu + 30dBu attenuation 100K load Audio band residuals are below -130 dBu. No distortion products visible. SA1X 50 Hz + 7000 Hz spectrum Left and Right 0dBu + 30dBu attenuation 100K load Y-axis changed to include -150 dBu. Output of anything other than 50 and 7000 Hz in the audio band is less than approximately -138 dBu, which is 97.6 nV or less than 100 billionths of a volt. SA1X 600 Hz + 1700 Hz spectrum Left and Right 0dBu + 30dBu attenuation 100K load Y-axis changed to include -150 dBu. Output of anything other than 600 and 1700 Hz in the audio band is less than approximately -138 dBu. SA1X IMD spectrum Left and Right -16dBu + 30dBu attenuation 100K load Should be a familiar theme by now. IMD is at the threshold of wire. SA1X residual noise spectrum Left and Right A=0dB + 30dBu attenuation 100K load What noise? there isn't any more than a wire would produce in the same measurement. Myth #5 busted.