Hammond 102 Series Mic / DI Transformers?
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Monte McGuire
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The rated LF response is 1dB down at 310Hz. This part would be good for voice communications work, like a Clearcom, but pretty useless for general recording aside from being a special effect.
I bet dollars to doughnuts that these are the old (1959) pocket transistor radio transformers, but in plastic boxes.
If so, they are indeed just-right for a 50-cent 3-inch speaker.
The rated bass response cna be improved if you drive with a very low impedance. The "10K" winding driven with an opamp may deliver a part-volt at 60Hz without gross distortion. The "600:600 500mW" part might pass +13dBm at 30Hz for <50 Ohm source.
The larger epoxy jobs have more specs:
http://www.hammondmfg.com/pdf/109H.pdf
Rated 0.78 Henry inductance. 0.78H does not hit 600 Ohms until 122Hz. And while you could work it down to 122Hz, the rated power (THD not specified) falls-off. They claim 300Hz for 2 Watts in 600 Ohms, which is 35 Volts(!). At 122Hz the limit is 122/300, or 0.41 times voltage, or 14V, which IS substantial... +25dBm. But the impedance is also 0.41 times 600 or 246 Ohms. From a zero-impedance source we might get response to 30Hz, but at only 3.5V, +13dBm, and the driver must pull less than 50 Ohms.
R.G. has an active guitar splitter using the 10K:10K tranny-radio trannies and it is very acceptable for guitar-level (part-Volt, 82Hz).
As general studio hacks, they won't do.
If so, they are indeed just-right for a 50-cent 3-inch speaker.
The rated bass response cna be improved if you drive with a very low impedance. The "10K" winding driven with an opamp may deliver a part-volt at 60Hz without gross distortion. The "600:600 500mW" part might pass +13dBm at 30Hz for <50 Ohm source.
The larger epoxy jobs have more specs:
http://www.hammondmfg.com/pdf/109H.pdf
Rated 0.78 Henry inductance. 0.78H does not hit 600 Ohms until 122Hz. And while you could work it down to 122Hz, the rated power (THD not specified) falls-off. They claim 300Hz for 2 Watts in 600 Ohms, which is 35 Volts(!). At 122Hz the limit is 122/300, or 0.41 times voltage, or 14V, which IS substantial... +25dBm. But the impedance is also 0.41 times 600 or 246 Ohms. From a zero-impedance source we might get response to 30Hz, but at only 3.5V, +13dBm, and the driver must pull less than 50 Ohms.
R.G. has an active guitar splitter using the 10K:10K tranny-radio trannies and it is very acceptable for guitar-level (part-Volt, 82Hz).
As general studio hacks, they won't do.
