US-company Shure started out in the mid-1920s selling DIY kits and electronic parts to radio enthusiasts. During the Great Depression the company’s focus shifted to microphones and – only a little later – to record player cartridges.

The original company’s first breakthrough came in 1939 with the Shure Model 55 Unidyne. The Model 55 Unidyne was the world’s first single-element, unidirectional (read: cardioid) dynamic microphone, making it the earliest cost-effective choice for any application, where you wanted to reduce bleed from other sound sources and feedback from the PA-system. An updated version of the Model 55 – colloquially known as the ”Elvis Mic” – is still produced today as the SH55.

By the 1950s microphone development had progressed from the original Unidyne capsule to the Unidyne II. All these mics were still so-called side-address, best kept attached to a stand, because you had to speak or sing into them sideways, like you still do with most large-diaphragm condenser microphones.

In 1959 Shure managed again to develop the right product at the right time:

Their new Shure 545SD Unidyne III model was the first ”end-firing” unidirectional dynamic mic. The 545’s improved pneumatically isolated capsule also drastically reduced handling noise. This meant that the user could take the microphone into his/her hand and move around the stage, without having to worry about handling noise and feedback obliterating the performance or speech.

The 545SD – and its only slightly younger brother the 565SD Unisphere I – quickly superseded the Model 55 as the preferred performance mic on stage and on the telly.

Speaking of TV:

Television studios loved the 545SD, because it sounded really good, while being small enough to not hide the face of the performer. There was one point of criticism, though, and that had to do with the mic’s finish.

The 545SD’s plain metal housing and its black plastic collar made the model very reflective under studio lighting. Before the advent of digital cameras, reflections were a real problem for TV cameras, because they caused ”burn marks” in the transmitted pictures. On black and white TV you would see large black blots or squiggles (during movement), while on colour TV these burned-through areas would often appear dark violet or brown. These marks would only be temporary – lasting for 10-15 seconds – but nevertheless annoying.

Shure listened to its customers and came up with a new model as a remedy in 1965. This new model was (and still is) the legendary Shure SM57, which features an all-metal housing sporting a non-reflective matte finish.

The SM in the model designation stands for ”Studio Microphone”, with the word ”Studio” hinting at a TV studio.

While the R & D team where at it, they tweaked the capsule’s/cartridge’s frequency response a little bit to distinguish the new model further from its predecessor, which was kept in production.

Along with its brother – the SM58 from 1966 – the Shure SM57 has become the company’s biggest selling microphone. This has led to the SM57 and SM58 also becoming the most-copied and most-pirated microphones ever.

The 545SD was the main product and could be handheld or placed on a stand by using a mic clip. Shure expanded the line by using the same design for a whole range of products, from a lavalier version to an installation version that was mounted permanently on a gooseneck.

The Shure 545S (shown above) was a so-called pistol version with the on/off-switch moved to the same position as on the Model 55.

The broadcast version for radio stations, the Shure 546, came with a special suspension inside its stand adapter to cut down handling noise even further.

One of the first touring PA-companies in the USA – Hanley Sound – quickly adopted the 546 as their main stage mic. Bill Hanley handled the Beatles’ final US tour in 1966 (see picture above). He was also responsible for the PA at the legendary Woodstock Festival in 1969, where he used the Shure 565 Unisphere I model as the main microphone.

Apart from its metal-cum-plastic body, there are three main features that differentiate the Shure 545SD from the SM57:

1. The 545SD can be switched from its default setting of low impedance to high impedance, simply by unscrewing the XLR-connector and moving a little jumper to a different position. Although there are much less applications in 2021 that require a high impedance mic (also called Hi-Z), this feature will come in very handy if you want to use the mic for Blues harp playing into a guitar amp.
2. The 545SD features Shure’s special magnetic reed on/off-switch, which works without annoying pops or crackles. If you want to avoid accidentally switching the mic off, you can lock the switch in the ”on” position using the metal plate just below the switch.
3. If you surf around the Internet you will find many claims from self-styled microphone experts that the SM57 was/is simply a way for Shure to use up factory seconds of the cartridges produced for the 545SD. This is simply not true! The Shure 545SD uses the cartridge model R45, while the SM57 uses a slightly different cartridge, called R57. The basic ingredients of both capsules are almost identical, and the plastic grille assembly is interchangeable between the two models, but the cartridges have been deliberately ”tuned” to slightly different frequency responses.

The SM57 has an all-metal body, a different cartridge (R57), no on/off-switch, and is low impedance (Low-Z) operation only.

With both models set to low impedance their nominal frequency response curves look like this (above):

The Shure 545SD’s bass response only goes down to 50 Hz, while there’s clearly a little boost in the region between 8 and 10 kHz. The SM57 offers a little more bass (down to 40 Hz), while there’s an earlier treble roll-off. The most critical frequencies between 200 Hz and 6 kHz look virtually identical in these graphs.

As a hands-on test I ran some pink noise through my Genelec 8030A monitors and recorded it simultaneously with both mic models. I used two Cranborne Audio Camden 500 preamps running at the same settings to record the microphones. A/B’ing reveals – at least to my ears – that, while both mics sound very similar, the 545SD really has a more open treble range compared to the SM57.

Here’s another A/B-clip, using the percussion tracks from the demo song.

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Here’s my opinion:

Although the differences between the Shure 545SD and the later SM57 aren’t really that obvious in real-life use, there’s still a place for the ”daddy of them all” on stage and in the studio. As always, everything has to do with the source material and knowing your equipment inside out.

If you’re looking to capture that elusive little smidgen of treble content off of a snare drum or vocal, the 545SD can make your work a bit easier. But if you’re running the 545SD in front of an already face-meltingly harsh guitar amp, this model’s treble response could be a little too much, making the SM57 a better choice.

In any case, both the Shure 545SD and the SM57 are bona fide classics with sterling track records. Either of these can hold its own for a wealth of applications on stage or in the studio.

Shure 545SD & SM57

• Shure 545SD – current price in Finland approx. 159 €

• Shure SM57 – current price in Finland approx. 99 €

Finnish distrubutor: Intersonic