Shure 517SA and 517SB
The first thing that has got to be highlighted is the £21.92 plus VAT price listed in the Shure press release which came with the mics. If the mics prove to have no shortcomings then they must be excellent value. I suppose initially one is suspicious that here will be something which will look and feel "made down to a price". We shall see.
I must confess to not being all that familiar with the extensive Shure range of mics. Nevertheless, on unpacking I immediately recognised the Shure style in general and thought that the 517s were in their typical presentation. They are called Unidyne B but I'm sure that the description is a type name, as it is applied to other mics in their range. Unidyne is a registered trade name and would indicate a unidirectional dynamic microphone, which is what the 517s are. The SA and SB suffixes refer to there being two basic versions. SB being the more usual nominal 150Ω job, whereas the SA is a high impedance type. Just that — "high", with no actual ohmic appendage in the Shure data sheet. Now could it be that this impedance business is still a cause of concern amongst E&MM readers? In case I'll pause the review to attempt enlightenment.
Some facts first of all. Mics of 150Ω, 200Ω, 600Ω or what have you are not connected to the input impedances the figures might seem to demand! Anything some five to ten times greater is intended, and this is the case with the majority of modern equipment, be they amps, recorders or mixers. They may quote "for 600Ω mics" but they will fit the convention mentioned. In the past with valve gear there was a need to "match" mics to their unavoidable high input impedances (100kΩ to 1MΩ at least) or there would not be sufficient voltage to drive the input. So step up voltage transformers were needed. But there is more to it than this. You cannot use long leads with high impedance circuits, due to the high shunt capacitance preventing the "arrival" of high frequencies at the amp. See Figure 1.
Low impedance circuits can tolerate a lot more shunt capacitance and hence longer leads are possible. Certainly the SA version is still needed where valve (or FET) inputs are providing the high impedance unless the somewhat messy separate transformer is employed. Whisper — the difference between the two types of Shure 517 is that the SA has a small transformer in its body.
The transformer in the 517SA is the only physical difference. The mic is heavy and solid with the capsule in a rubber moulded suspension. The capsule is user-replaceable by three soldered wires and is available as a spare part as is the grill screw on fitting. This is mainly plastic but it is flexible and in that sense will absorb the shock of a fall. An on/off switch is provided with a screwdriver locking "on" arrangement. A Switchcraft XLR connector is provided and an optional accessory cable C5-X was thoughtfully submitted for us to use. This has the female Switchcraft socket at one end and a tip and sleeve ¼" jackplug, screened, at the other — all standard arrangements. The mating at the mic end could surely be tighter though as it was easy to produce clunks in use.
Now I thought that I could lump together both versions throughout this physical description, but no, as we are back to the transformer again. The SB has a balanced output as one would expect — the lead used determining whether its connection remains so. The high impedance version is unbalanced out of the mic with pins 1 and 3 commoned and the signal on pin 2.
My usual usage with other mics to hand took place along with a few regular well used sound sources and other things happening at the time. It's just got to be said that there is nothing shrill, peaky and bass-less about these low cost Shures. I suppose I was expecting that! On the contrary, in the company of a Beyer SoundstarII moving coil and a Calrec CM 656D capacitor there was the sort of similarity that puts all the mics in the quality class. One can do a whole string of comparisons with numerous odd instruments and general sounds and although there are varying differences it is not possible to say that it is a particular mic being used at any one time unless one announces each or sticks to a particular order. Interestingly, in investigating the differences heard, one only had to use them in a different acoustic to get more confused. This bears out a point I seem to make no doubt too often for some, that an instrumental or vocal mic's sound is environment affected in the way it "colours" the sound. More so than "flat" crossed pair recording where the acoustic is being captured in its own right in a sort of addition to the instrumental sounds.
An interesting aspect that came to light as a result of the high impedance version was its use in a TEAC Model 2A mixer compared to the low impedance version. The TEAC needs the high impedance version! The level from the normal model was significantly lower and in consequence "noisier". The same applied to the Beyer. The Calrec being a "proper" capacitor does not follow the same rules.
Handling noise from the Shures was par for the course as was close-up proximity and popping. On the latter point I have a cure for that difficulty. Incidently the number of times I hear diaphram popping in local radio chat shows is excessive in my opinion. I'll reveal my simple arrangement in a future look at mics.
Summing up, it has to be admitted that there is excellent value in the Shure 517 pair. There aren't any nasties as far as I can gather so I can recommend it thoroughly and not just for those who must embrace economy.