Bosch's New Multi-Material Detector: GMS120 Professional

We asked what you thought of the Bosch DMF10 Zoom. You told us:

"I have experienced that the DMF10 is unreliable detecting wooden structures behind the wall for some reason. Works better with “knock on wood” technique. Mains voltage and metal works just fine…

The only ‘problem’ I have encountered with the tool is that the audible signal is at far too high a pitch for older users thus limiting the ease with which it could otherwise be used, having to rely purely on the visible signals.

Since I purchased my Bosch DMF10 Zoom, I have not been able to use it. I purchased it for DIY work on my house, but it does not seem to work. This is because all of the plasterboard in my timber framed house is backed with a thick layer of foil, this stops the tool from working."

And we got the message. So did Bosch.

While many of the issues you were having with the DMF10 Zoom were covered by RTFM, it was obvious that it wasn't the most popular detector we'd ever come across.

But this is Bosch we're talking about. They invented German technological efficiency*, so when the GMS120 Professional multi-material cable detectorlanded on our desk, nestling comfortably in its efficient little protective bag, we wondered if this, the latest piece of professional tech kit from Bosch would be, well, efficient.

* Bosch didn't actually invent German technological efficiency. Rudolf Diesel may have done that. But we're not actually sure.


The point is, Bosch seemed to have been listening (and that's why it's important for you to let us know what you think of the tools you're buying/using. We make sure the manufacturers hear about it. Seriously).

Screen shot 2010-11-15 at 18.09.22Bosch claim that it's the most reliable detector in it's class. Of course, they're going to say that, so we're keen to know how they back it up.

Firstly, they've set the device up so that it's automatically calibrated as soon as you turn it on. This mean that objects are going to be found without application errors (although we still recommend RTFM...).

Even deep lying objects are going to be found, up to 120mm. That's around 5 inches in old money.

The GMS120 also benefits from a multi-coloured LED. This isn't for cute decorative purposes. It's to help you "see" when you're close to underlying objects. Which is exactly the purpose of the tool. Hence, at a glance you'll be able to discern when you're right over a stud or an electrical cable.

Screen shot 2010-11-15 at 18.10.29The LED lights encircle a marking hole at the top of the device. This allows you to mark on the wall where that nail has to go. We think this is a great idea.

Another great feature is the "Centre Finder" scale. As you can see in the video, the backlit LCD screen will prominently display when you're right over the middle of the underlying material.

What about the audible signal? Will our older friends be able to pick up on the frequency? Neil and I consider ourselves young uns, so we can't comment on the auditory capacity of our elders. However, we have to say that it's loud. If you're having problems hearing the signal on the GMS120 then it's maybe time to give Puretone a call.

Screen shot 2010-11-15 at 18.07.20In terms of ergonomics, the GMS120 feels very good in the hand. Using it one-handed up against the Toolstop office wall was easy and the button layout is both intuitive and tactile. The screen looks good too, with what seems to be a fairly expansive viewing angle. And Bosch have used an easy-on-the-eye font for the display, including the hard-t0-ignore "Centre Finder" scale.

All in all, we get the impression that Bosch have picked up on the feedback for the DMF10 Zoom and have turned out a worthy successor in the GMS120 Professional.

What do you think? Let us know in the comments below.


Toolstop on Mon, 11 Jun 2012 15:08:14 +0100 (Likes: 0 / Dislikes: 0

Hi Tim, many thanks for your comments. The following is an extract from the user manual which is attached to the product page:

Working Advice
􀁦 Measuring values can be impaired through
certain ambient conditions. These include,
e.g., the proximity of other equipment that
produce strong magnetic or electromagnetic
fields, moisture, metallic building materials,
foil-laminated insulation materials or conductive
wallpaper or tiles. Therefore, please
also observe other information sources (e.g.
construction plans) before drilling, sawing or
routing into walls, ceilings or floors.

We are sorry the machine has not met your expectations but it is true to say that no detector will work in certain conditions where magnetic fields come into play.

Tim Brewster on Thu, 07 Jun 2012 19:14:45 +0100 (Likes: 0 / Dislikes: 0

Bosch GMS120

Could be a great bit of kit, but after
speaking to Bosch their technical team told me it doesn’t work with foil-backed
plasterboard as it reflects the signal!

Most houses now use Foil back plasterboard
so it DOSENT work in almost all modern houses!

Shame they don’t tell you that in the
advertisement but I suppose that they wouldn’t sell very many new models, only to people
who live in older houses without refurbished walls.

I have returned mine as not really fit for

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