Before doing the experiment, read The Slotted Line in section 2.4 of the text. While the slotted line is cumbersome to use and gives less accurate results when compared with the automated vector network analyzer, the slotted line is still the best way to learn about standing waves and impedance mismatches. This experiment also introduces the student to common waveguide components such as waveguide-to-coax adapters, isolators, wavemeters, slide-screw tuners, detectors, and attenuators. The 415E has scales calibrated in SWR, and relative power in db. To obtain good sensitivity, the RF signal is modulated with a 1 khz square wave the SWR meter contains a narrowband amplifier tuned to this frequency. This signal is measured with the HP 415E SWR meter. The diode operates in the square-law region, so its output voltage is proportional to power on the line. Slotted lines can be made with any type of transmission line (waveguide, coax, microstrip, etc.), but in all cases the electric field magnitude is measured along the line with a small probe antenna and diode detector. The Slotted Line Introduction: In this experiment we will use a waveguide slotted line to study the basic behavior of standing waves and to measure SWR, guide wavelength, and complex impedance. Guitars remain property of respective owners.1 ECE 584 Microwave Engineering Laboratory Experiments 1. Any copyright issues should be address to: We will attempt to resolve these issues quickly. I love the look of slotted headstocks and judging from sales volumes, I'm not alone!Įrrors are unintentional although we try very hard not to make them- corrections or feedback are always welcome! Guitars are property of individual owners.Īny infringement of copyright is entirely unintentional. It was Al Carruth who stated “For my money, slot or flat is an esthetic decision, and I don't lose any sleep over the tone one way or the other.” and I couldn't agree more. Of course, if you are careful with your guitar, there is no reason why a slotted headstock will be any less durable than a solid headstock- after all, we don't go around smashing guitar headstocks against mic stands everyday! John Greven agrees with me and is reluctant to offer slotted headstocks as a standard option in light of similar experiences. I feel that the slotted headstock does suffer one distinct disadvantage over solid headstocks: I have been more headstock cracks and breakage in vintage slot-head Martins than those with solid headstocks. This often occurs if there was too few 'throws' over the tuning post and can be remedied by fraying the teflon coating or allowing a few more throws over the tuning post. One aspect is the slot size- smaller slots can make the job difficult and there also the risk of scratches and damaged to finish.įurthermore, coated strings can often slip on slot heads due to the reduced friction. read more about this guitar hereĬertainly restringing a slot headstock differs from a solid. So there is no clear or easy answer as to determine the difference in tone between a slotted and solid headstock guitar. He attributes this to the fact that the slotted headstocks were left thicker than solids. slotted headstocks and have found no appreciable difference in weight. To confuse the matter, this does not appear to be the case in the vintage Martins, where John Arnold has weighted solid vs. However, other factors such as weight and mass which can play a part as slot heads often have lighter, open geared tuners as opposed to the heavier enclosed solid head tuners. The string break angle can easily be altered on either style of headstock and Carruth’s tests have revealed that the string vibrates in the same way once 15 degrees of break has been achieved on the nut or saddle. However, most modern luthiers like Al Carruth feel the tonal differences between a slot and solid head guitar are not necessarily solely due to the string break angle. One with a solid another with a slotted headstock and the factory workers preferred the audibly different sounding slotted version. The story goes that two prototypes of this model were made. In particular the deep bodied OO Martin "Women In Music" model. This creates an audible difference according to Boak, particularly on smaller-bodied guitars. In this article, I look at the differences in tone, restringing and durability.ĭick Boak at Martin once mentioned that slotheads exerted more tension on the strings due to a steeper angle from the nut to the tuner shaft. S lotted headstocks are often found on classical and 12 fret guitars and equally often there are myths surrounding the effect of the difference in construction vs.
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