Sony ECR-500 - Overview
Sony used a pentagonally shaped monopole electret diaphragm (about 5 microns thick with roughly the same radiating area as a 50mm diameter driver) and sacrificed a bit of efficiency to space the stators far apart to give the diaphragm room to move (shades of the later Stax Pro electrostatics!); thus this headphone has more bass than even the contemporary Stax SR-X Mark 2 and 3, though it is not as flat and cannot play as loud. Minimal mechanical damping means the backwave of the '500 is unimpeded which gives the 'phones an openness that's ideal for listening to binaural recordings. An amazing headphone for the time (1976) and even for an electrostatic of the time.
General Description of the Sound
ECR-500 is a warm mid-centric sounding headphone with an excellent, detailed head-stage and natural tonal balance. Transient response is very good due to its large yet lightweight diaphragm. Unlike most electrostatic headphones from the mid-1970s, ECR-500 produces extended, deep bass that is at the same time well-defined and detailed. Detail retrieval is overall less than that of the best later non-electret electrostatics such as the SR-Lambda but is on a par with many good modern dynamic headphones.
The headphone's true strength is its ability to portray sounds that seem to originate outside the skull, in particular sounds recorded binaurally.
ECR-500's presentation is very smooth without any harshness or strain, and this, together with good comfort from the circumaural earpads, makes them very good for that relaxed late-night listing session.
Pricing & Other Data of Interest
ECR-500 was not very expensive when it was on the US market, about $150 in 1976.
Frequency characteristics: 20Hz - 20kHz
Sensitivity: 90dB SPL(adapter input 1 Vrms 300Hz)
Maximum sound pressure: 120dB SPL
Distortion: less than -50dB (adapter input 3 Vrms 1kHz)
Cord length: 2m
Weight: 350g (without cable)
ECR-500 Disassembly Instructions
Gaining access to the fronts of the ECR drivers is as easy as any headphone; pull the pads off and it's a matter of removing a few screws that hold the baffles in place. In order to remove the drivers fully, however, you may want to get at the rear of the drivers which is a little more tricky. To do so get a flat head screw driver -preferably one with the biggest, dullest head you can find- and place it between the Black driver housing and Silver finished trim piece as seen in the picture below. Apply rotational force between the pieces by turning the screwdriver in your hand. You may want to repeat this a few times at different locations around the circumference of the trim piece in order to ease it off. As seen in the photograph below there's a Copper retaining piece inside the trim which glue was applied to during assembly. The glue has most likely caused this Copper piece to corrode to some degree so expect some amount of flaky gunk to fall out as you pry the trim off. With the trim removed you can pull the wires off the metal tabs which extend from the driver, feed the tabs back through their slots in the driver housing, and remove the driver completely.