Help identifying a mic transformer

[Mark Hammer]

A year or two back, I bought some old Dukane 2A68-model mixers a guy was selling, that were taken out of a church or other institutional installation.  Truthfully, although they worked, I bought them for the parts, and nice rack enclosures that I planned to repurpose.  They came with two transformer-isolated mic inputs.  The mic transformers are large sealed-and-shielded cylindrical types, that I figure might be used with better circuitry than was originally employed (one 5535 dual op-amp for the pair, and the rest of the mixer used 741s).  The only markings on them are "710-60-07" and "4808530", neither of which brings up any useful info (although it seems "710" is Hammond's manufacturer number).  They look like the Jensen transformer shown below, except that, unlike either the Jensen or Hammonds I see, these have solder lugs for direct connection to a PCB, rather than the wire leads and brackets for attaching that most seem to have.  I measure 12.9ohms DCR between one set of contacts, and 409ohms DCR between the other set.  The higher-resistance set is three pins, with the middle pin connected to the shield.

So, any ideas what I might compare these to, what their possible quality/desirability is, and suggested circuits to use them with?

[PRR]

I would assume 1:5 voltage, 1:25 impedance, nominally 200:5K but loaded much higher to reflect a bridging impedance to the mike.

Such a thing into the now-forgotten NE5535 opamp could be as low-hiss as anyone should need, and lots of slewrate. GBW says the opamps should not be run gain much over 10, but with 1:5 in the transformer and a presumably low bus level, this could be plenty. If you keep overall levels quite low the '741s will serve; if level is pushed you want something else in the hi-level stages.

DuCane was fallen on hard times in this era and I would not try to guess the transformer bandwidth. "Looking like" a Jensen or Hammond says nothing.

2A68A Remote Powered Mixer-preamplifier Panel
Rated Output Maximum +18dBm (600 Ohms load, single-ended) Nominal 1Vrms (+2dBm)
Distortion Less than 0.25%, 20Hz to 20,000Hz
Frequency Response +/–1dB, 20Hz to 20,000Hz (tone controls flat)
Sensitivity Microphone: 0.25mV; Auxiliary: 0.1Vrms
Noise Level Microphone: better than –63dBv (@ –67dBv input, BW 20,000Hz)
Auxiliary: better than –75dBv (@ 0.1Vrms input, BW 20,000Hz)
Master control off, –85dBv (@ nominal output)
Input Impedance Microphone: 200 Ohms or less (for source impedances of 250W or less), balanced input
Auxiliary: 100k Ohms (minimum), single-ended
Bridging input: 100,000 Ohms (minimum), single-ended
Load Impedance 600 Ohms or greater, single-ended
Tone Controls +/–12dB (boost and cut) bass 50Hz, treble 10,000Hz
Power Requirements 24Vdc to 30Vdc, 50mA
Dimensions 1-3/4” (4.5 cm) high, 19” (48.3 cm) wide, 8-1/2” (21.6 cm) deep
Finish Charcoal-colored, baked enamel
Connections Screw terminals and RCA phono jacks at rear of panel