Sigma JM-SG45 review

The latest from Sigma's SG line

  • £475

MusicRadar Verdict

At this price, what’s not to like?


  • +

    Rich full bodied sound that would love nothing better than to be on stage with you.


  • -

    No onboard tuner.

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For just under half a century, Sigma has produced some of the finest acoustics available on the market at a reasonable price. Simply put, its guitars will break your heart and not your bank account - music to our ears. 

Proudly established back in 1970, Sigma was the answer to the woes of guitar manufacturers across the US during what was a rather worrying time. Companies across America were hit hard by Japanese competitors who saturated the market with guitars that had all the hallmarks of American design, only to be sold at a fraction of the cost. 

The gauntlet had been thrown down and on the vanguard stood Sigma. Originally created by Pennsylvanian natives CF Martin & Co, Sigma embraced Japanese craftsmanship instead of turning their noses up to their rivals. There was no corner cutting here, Sigma set out to create guitars of an exceptional standard that were then shipped to the US for inspection to guarantee quality. 

Over the next four decades, Sigma remained modest in its success, letting its guitars speak for themselves. And in 2011 the German music company AMI bought the Sigma name after the line discontinued in 2007. 


This month we have the JM-SG45 guitar. Beautiful doesn’t cut it - this is a truly exquisite acoustic. The JM-SG45 bursts out of the gates all guns blazing, as Sigma has already labelled this guitar as one of their ‘Golden Era’ models, commemorating the legendary acoustics that were built in the US during the 1930s. 

Though perhaps not as flashy looking some guitars in the Sigma line, the craftsmanship is absolutely top notch. The SG45 has a beautifully rich, dark tone. Keeping with a solid sitka top, the mahogany back and sides help define this instrument’s sound within the series. Designed as a sloped shoulder dreadnought, the SG45 is complemented by a modern, thin oval shaped mahogany neck with an Indian rosewood fretboard, which plays as good as it feels. 


The tonality of the SG45 is focused on the mid and lower frequencies, but will happily brighten up those notes on the upper register if required. This guitar is a songwriter’s dream as it provides enough body and soul to fill any space on command. Strummed chords have a longer sustain that punch their way through the air that will leave your hair standing on edge. 

The SG45 does not to feature metallic machine-heads, with the nickel open-geared tuners with ivoroid knobs a change of pace in comparison with many of Sigma’s recently-reviewed guitars. Although mine were a little stiff. 

Experimenting with the tuning is a must. Playing in open G for example, really showcases the bass and mids the guitar has to offer. 

Fishman preamps are featured across the full range of the SG line, the SG45 included. Using the Sonitone, which again is nestled within the interior of the guitar, the flexibility of tonality is again quite limited. Amplification unlocks all those hidden tones that would have previously gone unnoticed before and will help you stand out on stage. 

On that note, this acoustic loves to perform, however there are a couple of things that could definitely help improve this guitar on the live circuit. Though it might impede on the overall look of the guitar, a small strap button would make all the difference. By no means is it the end of the world, but it’s something that is often overlooked. Again, an onboard tuner is greatly missed. As contemporary acoustics go, there aren’t many excuses these days not to have one, especially for what you would be paying. 

The SG series guitars are the underrated champions of their mid-priced realm. Not only is it refreshing to see guitars built with ambition in mind, but sharing that quality with the world is an unqualified luxury that shouldn’t be ignored.