Sigma SUM-2S Soprano Ukulele - REVIEW

21 Oct 2017

Sigma SUM-2S Soprano Ukulele - REVIEW

I don't know whether it's a result of my personal passion for them or just that the ukulele market is stronger in them generally, but it's time to look at yet another mahogany soprano. This time it's the very Martin-esque Sigma SUM-2S Soprano Ukulele

Sigma SUM-2S Soprano Ukulele

But before you also groan about this being 'yet another Martin copy', you should be aware that it's actually a Martin copy with quite a bit of provenance. You see, Sigma Guitars were set up BY Martin  in 1970 in an attempt to stem the tide of the (very good) Japanese guitars that were cloning Martin and others and stealing market share. How to beat the cloners? Become one yourself! And those original Sigma instruments were indeed VERY good too,  made to the same designs (in fact using the same blueprints as Martins) because Sigma essentially WERE Martin.

Times have changed a bit though and they are now no longer made in Japan, and Martin sold Sigma to the German AMI brand together with the rights to the original Martin designs some time ago. AMI then transferred production to Korea and then China and in 2015 released a range of Martin ukulele clones based on the original designs from Martin. So, like I say, this is a clone, but a clone with some provenance, albeit a somewhat disjointed one.

The SUM-2S forms part of a trio of mahogany ukuleles released by Sigma that also include the 2C (Concert) and 2T (Tenor) models. The 2S seems the most 'Martin-ey' to my eyes, and that's because it's closely modelled on a vintage Martin Style 2 soprano from the 1930's. And it DOES look like one in many ways, which is hardly surprising considering that Sigma history. I mean, if you are working from the blueprints it stands to reason!

This one is a very standard shaped soprano made from all solid mahogany with a double bout and curvy base that screams 'traditional' and 'old school'. The top and back are made from single pieces and the sides are in a pair. The whole thing is finished in a satin showing off the rather attractive swirly grain in the wood. It's very reminiscent of the Martin S1 I reviewed earlier this year, but actually looks, in some ways, nicer to my eyes. More 'finished' if you will. The grain is better lined up with the body orientation and just looks prettier too. The finish though is more reminiscent of modern models from the likes of Ohana and Kala, with that almost 'too' flat satin that means you don't feel the wood grain despite seeing it. I think that's a real shame as it's the one thing on the instrument that doesn't feel in any way traditional to me. In fact what also irritated me is that the limited shop photographs of these I have seen don't really indicate that you are getting this sort of finish. Ho hum, not the end of the world I guess, but don't go expecting a hand rubbed, oiled finish. On this front it's no match for the Martin.

Sigma SUM-2S Soprano Ukulele body

The added decoration is nice though, and of course the Martin S1 didn't have much at all. This on the other hand has an attractive black white black edge purfling complimenting the cream binding, but the sound hole rosette in black and white concentric circles is also less stark than that on the S1. It's still a transfer which is a shame, but then, so is the Martin. This just looks classier I think and fits the instrument.

Sigma SUM-2S Soprano Ukulele bridgeFor the bridge we have a rosewood slotted mount with a bone saddle that is very reminiscent of Martins new and old. Just like the Martin, the saddle sits in a contained slot rather than a slot cut right through the bridge edge to edge, so it looks even more authentic than something like an Ohana or Hamano Martin copy.

Looking inside and it's also very neat and tidy and I love how there is no makers label, rather the Sigma logo is pyro embossed on the back wood itself. Very traditional and more on that logo later. Incidentally, that logo, model number and serial number are also embossed on the neck block which is also nice. We've also got very neat notched linings and thin braces with absolutely no mess whatsoever. Top marks here.

Sigma SUM-2S Soprano Ukulele sound hole

Up to the neck and this is made of mahogany that appears to be made from a single piece. That's surprising for a Chinese instrument, and nice to see. It's hard to tell if it is attached with a dovetail like the Martins are, but it wouldn't surprise me if they worked from original design plans. The profile seems a little more rounded than the very flat Martin and we have a pleasing nut width of 36mm. Cool.

Topping this is a rosewood fingerboard which extends over the top of the body housing a generous 17 nickel silver frets with 12 to the body. They are not bound, but the edges are dressed very well. The end of the fingerboard also shows off the traditional Martin shaping. Whether they will be changing that Rosewood to comply with CITES, I don't know but I suspect they will need to consider it. One thing I will point out here is that many soprano fans don't like the fingerboards that extend over the top of the instrument for fear that they affect the tone. Kiwaya make a shorter fingerboard version of their KTS-5 (the KTS-4) for that reason. With the KTS-5 though, that fingerboard, whilst it over hangs, is supremely thin and delicate. Here however we have quite a chunk of wood on the top.

Sigma SUM-2S Soprano Ukulele fingerboard

Position markers are also suitably Martin with outward dots at the 5th, 7th and 10th (the 7th being a double) and side markers that follow these positions but with extras at the 3rd, 12th and 15th. The dots are larger than those on a Martin, but that's no bad thing when you have eyesight like mine!

Beyond the bone nut and we find that the headstock is similar to Martin with a crown top. On the front is the Sigma logo which is also very Martin looking in it's style too - again unsurprising as Martin designed it. It's a transfer of course, but still far better looking than the gold sticker on the Martin S1 and it's quite subtle and aged looking, rather like the logos on higher end Kiwaya instruments. I like this.

Sigma SUM-2S Soprano Ukulele headstock

Flipping it over and we have my second gripe. The tuners. Sure, they are friction pegs (how could they be anything else on an authentic soprano?), but they are really pretty cheap ones with the plastic buttons creating friction onto plastic collars. They are the sort of friction pegs that give friction pegs a bad name to be honest. They look great, and I love the cream colour, but you will want to swap these out for certain I would say.  Thankfully that is a really easy job as I suspect most Grovers will be a straight swap in the holes left behind. Yes, these ones do hold, but they can be a pain to set right and there are, simply, much smoother friction pegs out there. Grover 4's or 6's spring to mind. Heck, some Gotoh UPT's would look killer on this!

Sigma SUM-2S Soprano Ukulele tuners

The package is completed with a decent quality padded gig bag bearing the Sigma name (that appears pretty much identical to the padded bags that entry Martins come with, only black) and a set of Aquila strings. I think that is a shame too, as they really should have gone with Martin strings to finish off the authenticity? Again though, an easy swap and one I would go for personally.  And that can be yours for around £225  which is a pretty keen price for this sort of build. I am not however seeing them in the USA and I 'believe' that as part of the deal during the sale of Sigma to AMI as they required that Sigma don't sell under the Martin name in the USA. Sigma guitars are sold there under the name of 'Kindred Guitars' but I don't see a ukulele version. Please correct me if I am wrong on this, but looking on their website and there is no US distributor. Sorry USA.

It's a nice feeling instrument, very light and balanced as is so important with a soprano and despite that 'factory' style satin it is rather nice in the hands too. Setup was good too with a very low action at the saddle, and a nut that I could possibly take down a touch, but isn't uncomfortably high. Certainly nothing I would rush to change.

And when it comes to sound, you should know what I am going to say by now. A soprano is foremost the rythmical option amongst the ukulele scales. An instrument really designed to be played with fast strum patterns, and for that it needs to have a good staccato bark and a punch. Thankfully this Sigma has it where it counts. It doesn't quite have that melt your face trademark jangle of a Martin ukulele but it still has a very nice punchy voice, more reminiscent of the Ohana SK-35, but to my ears, richer and rounder than that.

It's also a very playable instrument. By that I mean the combination of light weight and comfortable neck make it a joy to sit and play freehand with no straps or other cumbersome additions. When you add in the good resonance and lively tone it's got that 'aching to be played' feel too. In fact you can get great tones out of this with the lightest touch.

Sigma SUM-2S Soprano Ukulele back

It IS remarkably similar to the S1. In volume terms it's certainly comparable and it has a very very pleasant tone. This mellows the bright tone of the S1 down a touch, and may be a different option in the same scale package for people who want a less punchy sound. It's only subtly different, but come on - it's also the best part of £200 cheaper. All in all, this one is doing everything you want in a traditional mahogany soprano very well indeed.

This one my not quite give you the kudos of a Martin, but it could well BE one. And if you are comparing it to other value Martin clones like the Ohana SK35 and the Hamano, then I'd say this one takes the 'crown'. It's a shame about that finish and those tuners, but those things are far from end of the world stuff (plus one is easily changed). Recommended and this came awfully close to a 'highly recommended'! If you are looking for a traditional looking, sounding and good value mahogany soprano, i'd buy one in a heartbeat.


Great looks
Martin blueprint build and quality
Classy non stark decorations
Great volume and tone, with great soprano bark
Nicely dressed fingerboard and frets
Very fair price


Artificial looking and feeling flat finish
Average friction pegs


Looks - 9 out of 10
Fit and finish - 8.5 out of 10
Sound - 9 out of 10
Value for money - 9 out of 10






  1. Hi Barry, this is a very good review, like all you did and do. There is some logic in the selling to AMI. AMI is the distributor for Martin (and Sigma) for the European market, so I guess, that this was a natural move by Martin. In fact, this is the "old" version with that Martin designed logo in script. There was a design change in the logo afterwards towards the other Sigma logo design with block letters. But the build of both versions is identical, both having been build with dovetail neck joints just like the Martins. The newer however has the new micarta fingerboard just like the new Martins have due to Cites regulations. The older has the Rosewood fingerboard. Sadly, both versions are discontinued by AMI/Sigma and only a few are availlable in some store who hade them stocked. The old version is comparably rare, the newer version still around in some shops. I agree, the nut could have some setup, but I think, this is very nice, because it lets you decide, how you want it. It is not bad, so can be used as is without problems. This is very nice in my opinion as it has the right balance between being playable as is with a bit of space for individual tuning. Thanks again! Cheers Chris

  2. I have to stand corrected: AMI is the distributor of CF Martin Guitars for Germany, not Europe. By the way, if folks are interested in getting one of these, I have the concert size and I swapped the strings for Worth brown Low-G and now it has perfect intonation all over the fretboard and a perfectt action. It sounds very vintage and nice with them, so it makes sense to try out different strings before messing around with the action. Cheers Chris

  3. I’ve just bought one of these with the old-style logo and what looks like a rosewood fingerboard. It’s got the most comfortable neck I’ve ever held and feels so solidly (perhaps confidently would express it better?) built while producing a lovely, lively tone. I’m going to enjoy playing this one, it’s a really lovely uke. Thanks, Baz.


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