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Internal SLOW Blow Superfuse

5 out of 5
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  • Replacement 20mm (internal) slow blow fuse (fast blow fuses are available here)

  • Features a specially-developed version of our Super Burn In treatment

  • Available in a range of values from 100mA to 10A

  • Includes DeoxIT Gold wipe for treating end caps before fitting

  • Supplied as a single fuse

  • The Russ Andrews 20mm slow blow SuperFuse™ is a replacement internal fuse designed to replace fuses in equipment. They feature a specially-developed version of our unique Super Burn In process. The SuperFuses are supplied with a DeoxIT™ Gold wipe for treatment just before fitting.

    Available in a range of values, you should always replace an existing internal fuse with a SuperFuse of the same value and type.

    Read our Guide to SuperFuses

    What's included

    Single 20mm internal slow blow SuperFuse, DeoxIT Gold wipe, 'Fitted with SuperFuse' label, instructions, protective pouch.

    Information Downloads

    Buying Guide


    Russ Andrews specification 20mm internal slow blow fuses
    Unique Super Burn In treatment
    Length: 20mm Diameter: 5mm
    Glass body
    Supplied with DeoxIT Gold wipe
    Excluded from our Lifetime Warranty

    "the cost is actually lower than many other audiophile fuses and does result in tangible sonic benefits.”
    Read more about the Hi-Fi Choice review here

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    60 Day Money Back Guarantee
    SuperFuses are covered by our 60 Day Money Back Guarantee: audition them in your own system for two months. Find out more.
    Customer Reviews
    Overall product rating 5 / 5
    5 / 5

    reviewed by Neil. Shrewsbury
    11 Mar 2024
    Yes, I recommend this product.
    "Great Value Upgrade For Small Money"
    Whilst fitting my Denon 900 CD player with an RA sound deadening Pad and oak cone feet I saw that the internal PSU had a 315ma fuse fitted, so ordered a superfuse to replace that at the same time.

    THe deadening pad and feet added a spaciousness and clarity to the sound, and the use added refinement.

    So for circa £75 an improvement that people can ( and will) pay £100s of pounds for. Highly recommended before you start paying thousands for a new CD player.
    5 / 5

    reviewed by Alan Sheridan
    11 Mar 2024
    Yes, I recommend this product.
    "Worth Every Penny"
    Having progressed through RA cables, X block, Power Purifier, earthing, The Supplier and Super fuses giving way to Ultra fuses what could a Slow Blow Superfuse possibly do for my Auralic Aeries streamer? Apart from improving bass response, clarity and three dimensional positioning not a lot. Unbelievable for the money and ease of fitting.
    5 / 5

    reviewed by Ray Duggan
    07 Jan 2024
    Yes, I recommend this product.
    "Well Done Russ!"
    After installing more internal superfuses in my CD drive/Dac, and 2 days on I am very pleased with the result obviously helped by the 13 amp Ultra fuse.
    I can also confirm that the SFs still need to burn in the natural way as I am hearing more transparency in the midband as time goes on.....well done Russ,Peter,Simon and John and Uncle Tom Cobley and all.
    5 / 5

    reviewed by David Hossack
    08 May 2018
    Yes, I recommend this product.
    Having used the mains superfuses to good effect I ordered 2 internal superfuses last week, one for my CD player and another for the amplifier I have to say I'm very impressed with the improvements. Maybe there's an accumalative effect with the mains superfuses!! My Audiolab 8200 CD player has always sounded detailed but now sounds even more detailed on familiar discs as well as all round improvements in bass quality, stereo imaging, treble sweetness and textures, worth every penny!!
    5 / 5

    reviewed by Jimbob
    26 Mar 2018
    Yes, I recommend this product.
    "Very Impressive"
    After using some of the mains plug Superfuses and being pleasantly surprised I bought a couple of internal Superfuses to try in my valve power amplifiers. Unlike lots of other audiophile fuses these Superfuses sound tip top straight away. Having listened to lots of Russ’ products over the years I would say that the ‘house sound’ is just a very natural, easy, musical one, and these fuses deliver that in spades. They have also removed a niggling high frequency glare that I was blaming my new listening room for. Room treatments didn’t solve the problem, but these very modestly priced fuses did, and without the need for a lot of ugly bits and pieces stuck around the room! Cheers Russ, I will certainly be getting a lot more of these great fuses.
    5 / 5

    reviewed by Howard
    11 Aug 2017
    Yes, I recommend this product.
    "Slow Blow Internal Superfuse"
    Tighter base, sweeter treble, less sibilance and more detail - what's not to like? This is the first internal SuperFuse I've fitted (to my Naim Nait XS Amp) and the improvement is clear. Not cheap but worth every penny!
    5 / 5

    reviewed by Johnny
    06 Jul 2017
    Yes, I recommend this product.
    "Ra Superfuse"
    Once again another great product from Russ and the Team, i highly recommend these fuses,they do make a big difference for the better in any electrical device they have been fitted to,i have brought over ten of these,RA customer for 20 years, Highly Recommended
    5 / 5

    reviewed by anonymous
    10 Jun 2017
    Yes, I recommend this product.
    "Internal Super Fuse"
    I have these fitted to my CD player and amplifier. I am suprised at the extra detail and tighter bass compared with the original fuse. The sound is altogether 'cleaner' and sweeter than the original fuse. A very effective and reasonably priced upgrade.
    5 / 5

    reviewed by Chris maddern
    07 Apr 2017
    Yes, I recommend this product.
    "Re Superfuses"
    I have been using another brand of fuse, but after trying one I have replaced main fuses and internal fuses with super fuses. I have to say that I much prefer the sound. I used to be a sceptic but after all the effort of dedicated supply, cables and plugs and supersockets it really is the icing on the cake.
    5 / 5

    reviewed by paul
    28 Mar 2017
    Yes, I recommend this product.
    "Astonishing Upgrade"
    superfuses are even better when used from wall plug to equipment leads to internal fuses I was cautious/sceptical so did it bit at a time although it got quicker as I heard the results. I considered my system well sorted and at a pinnacle of performance so did my family. so think not expensive fuses but a real upgrade for a bargain price.!!!
    5 / 5

    reviewed by nigel sheepwash
    29 Dec 2016
    Yes, I recommend this product.
    "Excellent Product With A Really Noticeable Effect"
    My system already has reference powercords fitted with Superfuses and I had already experienced their affect. Have just fitted the one in my cinema amp and WOW! Listened to a best of Billy Joel album that had previously been dct treated. First few chords and I was blown away. As other reviewers have said, the bass seems tighter and there is a lot more detail across the whole range.
    5 / 5

    reviewed by Andrew Smith
    18 Mar 2016
    Yes, I recommend this product.
    "I Would Recommend This Product."
    I have just fitted these to my CD player and intregated amplifier. These were already connected to the mains by Powerkords fitted with Superfuses. It was immediately apparent that the bass was both tighter and deeper. There was also an increase in detail across the frequency range. These improvements were very noticeable so any doubters should try these before forming an opinion.
    5 / 5

    reviewed by Pete Cable
    22 Jan 2016
    Yes, I recommend this product.
    "Amazing Improvement"
    I've been waiting patiently for Russ to produce slow blow internal Super Fuses and so thrilled when at last they appeared. My SuperKords are already fitted with 13amp Super Fuses and so I know what they can do. My equipment is also fitted out with the excellent Russ Andrews DCT internal fuses and so I was really keen to see what the slow blow Super Fuses could do. I was not disappointed. Fitted into my cd player, straight from the first track I was startled by the improvement. More detail ' I hadn't heard that before', highly realistic portrayal of the musical imagery, sweeter rendition, particularly of string instruments. In short, splendid improvements all round. When funds allow I shall be purchasing more fuses for my pre and power amps. Can't wait to see what that will do for the musicality of my system.