Should I put ferrites on my BNC or USB cables, and which kind?

Practical answer. For USB, Watts said his tests showed no change from ferrites on USB cables Head-Fi, Jan 2018. For BNC from a Hugo M Scaler, he said clip-on ferrites sound worse, while solid-core ferrites rated above about 2 GHz, or Wave cables, give a small improvement Head-Fi, Apr 2020Head-Fi, Nov 2019Head-Fi, Oct 2021. For the Quartet he said you need not worry about BNC cables as you did with the Hugo M Scaler ConvinceMeAudio 10:47.

USB cables

• No change heard (2017 to 2019). In October 2017 (Hugo 2) he said he would be amazed if ferrites on the USB cable made any difference Head-Fi, Oct 2017. In January 2018 he repeated that they made no change, adding "differing sources may give different results" Head-Fi, Jan 2018.
• If you try anyway. In December 2017 he suggested noisier sources might respond, and that 300 MHz to 1 GHz types would be more appropriate for USB Head-Fi, Dec 2017. In 2018 and 2019 he again suggested trying 300 MHz types Head-Fi, Apr 2018Head-Fi, Apr 2019.
• Already built in. In January 2018 he said Hugo 2 has chip ferrites on the USB ground as well as VBUS Head-Fi, Jan 2018Head-Fi, Jan 2018. In May 2020 he said he had done this on all designs for about five years Head-Fi, May 2020. He said Mojo has ferrites in the USB ground (October 2021) and Mojo 2 does too (February 2022) Head-Fi, Oct 2021Head-Fi, Feb 2022.
• The cable itself. In 2018 and 2022 he said certified class 2 USB cables sound the same, while audiophile ones can add RF noise and sound worse Head-Fi, Dec 2018Head-Fi, Dec 2022.

BNC cables

• Blu 2 to Dave (2017 to 2018). Here high-frequency ferrites helped: in November 2017 he said ones with higher impedance at 2.5 GHz sounded marginally better Head-Fi, Nov 2017, and he used HF ferrites at the Dave end and lower-frequency ones toward the Blu 2 Head-Fi, Dec 2017. Later he said clip-ons worked with the Blu 2 Head-Fi, Dec 2018Head-Fi, Aug 2020.
• Hugo M Scaler, clip-on types. In August 2018 he said its improved BNC isolation meant "you don't need to worry about ferrites" Head-Fi, Aug 2018. From September 2018 to April 2021 he reported that clip-on ferrites made it sound brighter, flatter or with poorer depth, which he had not expected Head-Fi, Sep 2018Head-Fi, Nov 2018Head-Fi, Nov 2019Head-Fi, Apr 2021.
• Hugo M Scaler, solid-core types. In November 2019 he said solid-core ferrites still improve the sound, "but I should add that it's not a huge difference" Head-Fi, Nov 2019. In August 2020 he said solid-core 2 GHz ferrites give the largest improvement and that he uses Wave cables himself Head-Fi, Aug 2020. In October 2021 he said the supplied BNC cables are "to get you going"; to solve the problem completely, fit solid-core 2 GHz ferrites or try Wave cables Head-Fi, Oct 2021. In July 2024 he recalled the M Scaler needed ferrite BNC cables for the best sound, "It wasn't a huge difference, but it was noticeable" HIFICLUB 45:42.
• Choosing a core. In April 2020 he said the best solid cores need a resonant frequency above 2 GHz; when data-sheet plots stop at 1 GHz, pick the core with the lowest impedance at 100 MHz, and fit it as close as possible to the cable's shield Head-Fi, Apr 2020. In August 2020 he advised against looping the wire around the ferrite, since looping adds parasitic capacitance Head-Fi, Aug 2020. In April 2022 he said the units are better kept apart than stacked when using solid-core ferrite BNC cables Head-Fi, Apr 2022Head-Fi, Apr 2022.
• Alternatives he named. In August 2020 he said a 2 m cable gives roughly 25 to 33% of the gain of GHz solid-core ferrites Head-Fi, Aug 2020. In June 2023 he said an isolated power bank or Wave cables each stop the ground-current flow, so one is enough, and that it "isn't a night and day difference, but it will make a difference when you do a careful AB test" Head-Fi, Jun 2023. In 2022 and 2023 he said that with a power bank and optical input, stock BNC cables were fine Head-Fi, Dec 2022Head-Fi, Sep 2023.

Quartet

In May 2024 he said the Quartet's filtering keeps noise inside the product, so it sounds the same as a battery ConvinceMeAudio 10:19ConvinceMeAudio 10:47. In July 2024 he said its power supply makes it less sensitive to your BNC cables HIFICLUB 46:35.

Other cables

In 2018 and 2021 he warned against ferrites or inductors in analog signal paths such as headphone cables, citing non-linear inductance Head-Fi, Feb 2018Head-Fi, Apr 2021. Earlier, in April 2014, he had suggested trying ferrite cores on the headphone cable as a possible fix for Bluetooth-transmitter interference with the original Hugo Head-Fi, Apr 2014. On mains cables he heard no change from ferrites with Dave Head-Fi, Apr 2018Head-Fi, Jun 2023.

What the record does not cover: he has not said whether ferrites help or hurt a Quartet's BNC cables. He called the RND core he compared "the better of the two, but it is not ideal" Head-Fi, Apr 2020; the part he linked for Blu 2 in 2017 is missing from the archived text Head-Fi, Nov 2017.

Quotes

“My listening tests revealed no change with ferrites on USB cables at all.”2018-01-11 Head-Fi, Jan 2018

“Don't use the clip-on types, as they actually make the performance worse.”2020-04-23 Head-Fi, Apr 2020

“Solid core 2GHz ferrites do work and will give the largest improvement”2020-08-10 Head-Fi, Aug 2020

“you don't have to worry about your BNC cables in the way that you used to have to worry with the Hugo M Scaler.”2024-05-16 ConvinceMeAudio 10:47

Dated positions

Caveats and open points

• The USB ferrite tests he describes used his own laptop; he said noisier sources may differ.
• He gave no statement on ferrites for Quartet BNC cables.
• The 2014 headphone-cable suggestion and the 2018 to 2021 warnings both appear; the record does not say he revisited the 2014 advice.

Topics: Cables, adaptors and ferrites, RF noise: mechanisms and audibility