LH95 Inductor EQ
The Iron Age LH95 is a highly flexible, discrete class A active equalizer in the 500 series format. It features a discrete audio path, three vintage class A gain blocks, transformer balanced inputs and outputs, and an inductor mid band.
The equalizer is set up for broad, musical adjustments on the high and low end of the audio band with an active Baxandall stage. The high and low bands allow for up to 15 dB of shelving boost or cut in 3 dB increments, at 40 Hz for bass and 15 kHz for treble.
The mid band stage is a variable frequency presence filter using a custom-wound multitap inductor from Cinemag. It provides up to 8 dB of boost or cut in 2 dB increments. Boost and cut frequencies are approximately mirror-inverted.
Additionally, the EQ features switchable high pass and low pass filters with -3 dB points at 75 Hz and 13.5 kHz.
Gain Range +/-15 dB, bass and treble in 3 dB increments
+/-8 dB, presence in 2 dB increments
Maximum Input Level +18 dBu
Maximum Output Level +21 dBu
Input Impedance approx. 5.6kOhms, transformer balanced
Output Impedance <45 Ohms, transformer balanced
Frequency Response, set flat +/-0.5 dB 40 Hz - 16 kHz
Noise <-85 dBA
THD @ +15 dBu output <1% typical
Power Consumption approx. 90 mA
The IN/OUT button switches the EQ in when depressed. When the unit is not in, a true bypass circuit is engaged, connecting the channel input directly to the output with no other components in the signal path. When the EQ is engaged, the LED over the switch is illuminated.
The treble and bass EQ bands have identical controls. The amount of boost or cut is selected by the 11 position gain switch.
The presence band has a frequency selection switch and a gain switch. The amount of boost or cut is selected by the 9 position gain switch, and the center frequency is selected by the 6 position gain switch.
The HPF and LPF switches are each two position toggles which engage the filters.
EQ Frequency Response
Graphs created with empirical data from production LH95 unit