The S-DUO PRO by HumminGuru is the latest incarnation of their ultrasonic stylus cleaner and tracking for gauge. Is this a must-have turntable accessory, or is it just another hi-fi gimmick?
The S-DUO Pro replaced the original S-DUO, introducing upgrades in the form of a rechargeable battery and built-in accessory storage.
Rechargability, in particular, is a welcome upgrade, as some users had reported frustration over battery life with the previous model. In addition, including built-in accessory storage means the new version immediately feels like a more refined design.
Just like its predecessor, the S-DUO Pro combines ultrasonic stylus cleaning and tracking force measurement into a single unit, allowing you to simply flip the unit around depending on which function you need.
It’s a neat idea, and the LCD display even changes orientation seamlessly as you flip the unit around. Smart.
Maintaining a clean stylus and ensuring correct tracking force are two of the most important elements of turntable maintenance, so regardless of whether you decide this product is worth your hard-earned money, you should clean your stylus regularly and periodically check your cartridge tracking force.
Why Ultrasonic Cleaning?
Most stylus cleaning methods rely on manual tools—brushes, gels, or pads—that physically contact the stylus to remove dust and debris.
Ultrasonic cleaning offers a contactless alternative. For those who are new to the ultrasonic concept, it works by generating high-frequency sound waves in a liquid bath that create microscopic bubbles. These bubbles collapse with enough force to dislodge dirt, dust, and even hardened grime from the stylus tip—without any physical scrubbing.
Another benefit is that it works using just water (I use distilled water), which means there is no need to use cleaning fluids with solvents, such as alcohol.
This takes a little longer than using a traditional stylus cleaning brush (such as the GrooveWasher SC1 stylus cleaning kit). Still, it does reduce the risk of slipping and damaging the stylus cantilever when using a brush.
Features & Functions
The S-DUO is a neat and compact dome shape with a clear LCD display positioned on top. Two buttons to the left and right of the screen provide the main controls, and the power switch is now located underneath the unit; it was previously on top near the LCD.
Unlike the original S-DUO, the new model sits neatly on top of a USB-C charging dock, removing the need for expensive AAA batteries but also cleverly incorporating storage space for the necessary ultrasonic cleaning accessories.
The accessories include three stylus rubber supports, two drying pads, and a 0.5ml water dropper.
The rubber supports are required to ensure compatibility with a wide range of cartridges. HumminGuru provides a handy chart showing which rubber support is best for a selection of the most common cartridges on the market.
Important! – The stylus must be able to sit in the ultrasonic bath without the cantilever touching the rubber support and without the stylus tip touching the base of the water basin.
The ability to store the accessories inside the charger base feels like a huge upgrade from the previous design, as it makes storage of the S-DUO Pro even more compact.
S-DUO Pro in Use
I used the S-DUO Pro to clean an Ortofon 2M Blue stylus, which, according to HumminGuru’s handy compatibility list calls for either the number 1 or number 2 rubber support.
I opted for the first option as it allowed less of the stylus body to touch fluid while easily making space for the cantilever and stylus tip to enter.
Once the rubber support was fully inside the water basin, I used the water dropper to fill the basin all the way up with distilled water.
After lowering the stylus into the bath, I could start the ultrasonic process by pressing the button indicated by a water drop icon. This initiates a 20-second cleaning cycle. You can very faintly hear the ultrasound noise as the 110kHz frequency works on the water.
It’s a quick cycle, and on visual inspection by the naked eye, I could see the stylus looked much cleaner.
There are a few reviews of the S-DUO out there, but I’ve yet to see anyone use a microscope to show the results.
I checked it out under my USB microscope and found that the stylus was significantly cleaner. Not perfect, but then I had just played side A & B of a very dirty record.
I gave the stylus a second run in the S-DUO and the results improved further.
Wanting to get a perfectly clean stylus, I tried it one more time, and there we have it: a pristine stylus.
Note: You can use the drying pads to absorb the remainign water in the ultrasonic basin and to dry the stylus. It is advised by HumminGuru that you wet and then dry these pads before first use as they arrive very firm fresh out of the pack. First use with water will soften them up.
Stylus Cleaning Brush Vs Ultrasonic Stylus Cleaning
There are pros and cons to any cleaning method. My usual approach is to use a small drop of GrooveWasher SC1 stylus cleaning fluid and gently pull the brush over the stylus from back to front.
I don’t use the gel-based stylus cleaners, as frankly, I don’t like the approach — some people have even reported residue being left behind with those products.
I find my GrooveWasher approach works really well and is super quick and easy. However, granted, there is more risk of cantilever damage with any contact-based cleaning method. That, and some folks will shy away from cleaning products containing anything other than water when it comes to stylus cleaning.
From my tests, the S-DUO does a great job of cleaning, but it might take two or three cycles to fully remove stubborn grime and dust. Then again, when using a brush, you will generally pull it over the stylus multiple times to clean it fully, so perhaps there are no surprises here.
All-in-all, the S-DUO Pro is an extremely gentle and and effective way to deep-clean your stylus.
S-DUO Pro Tracking Force Guage
Flip the S-DUO Pro 180 degrees and we’re in tracking force mode, which works just as you might expect. As mentioned earlier, the display even rotates automatically.
Simply press the tracking force button, ensure the display reads zero, and lower the stylus tip onto the black dot to check your tracking force.
For years, I’ve been using a Neoteck tracking force gauge, and the S-DUO Pro definitely feels like a significant upgrade.
The pressure gauge is said to be accurate within 0.01 grams, but there is a small 5g weight that we can use to check this and calibrate the device if necessary. Unlike my basic Neoteck gauge, the S-DUO Pro has a handy slot for storing the calibration weight.
HumminGuru recommends periodically checking the accuracy using the 5g weight and following their instructions for calibration if and when necessary.
I’ve always recommended every turntable enthusiast own a stylus pressure gauge to ensure the most accurate setup. To have one neatly combined with an ultrasonic stylus cleaner makes this little device a handy bit of kit.
The Bottom Line: Should You Buy the S-DUO Pro
HumminGuru have taken their original concept and refined the design further to make turntable setup and maintenance easy and more enjoyable.
The rechargeable battery and accessory storage have ironed out some of the pitfalls of the original model, showing that the company is eagerly listening to customer feedback and striving for better design.
In my humble opinion, the HumminGuru logo sticker on top of the lid could be improved in quality; mine has a couple of bubble imperfections which cheapens the feel a little. This is a minor aesthetic complaint, but ideally, their logo would be printed directly on the surface.
While it does take longer to clean your stylus than a traditional brush, it greatly reduces contact and allows deep cleaning using just distilled water. I think a lot of record enthusiasts will appreciate this.
I can highly recommend the S-DUO Pro for anyone wanting to deep-clean their stylus without using cleaning fluids in a safe, low-contact way. For me, it’s a device I will use once a month to give my stylus a deep clean alongside my daily stylus cleaning ritual. The tracking force gauge function will now replace my Neoteck gauge as it is simply much nicer to use.
Well done, HumminGuru; far from being a gimmick, the S-DUO Pro is a highly effective and useful turntable accessory that will find a natural home in many vinyl enthusiasts’ homes.
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