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The H9 is a mic and line preamp, high pass filter, and equalizer in the 500 series format. The mic preamp and EQ combine for an instantly recognizable character and are all incredibly useful professional tools for tracking or mixdown. 


The H9 features a transformer coupled, discrete Class A mic pre. The amplifier gives a snappy, open vibe with a woody character that’s perfect for any source. It handles transients with an ease and clarity that captures the essence like you're in the room. A Jensen input transformer carefully selected to match the amplifier plays a key role in the sonics and low-noise performance of the design.

A single precision rotary switch controls the input mode. Mic gain is available from 0 to 70 dB in 10 dB steps. The clockwise positions activate a line level input at +10, 0 and -10 dB gain, and automatically disconnect the 48V phantom power from the input.

The H9’s equalizer is a classic three band passive design. Each band uses a precision rotary switch for control. The high shelf gives unmatched air and sparkle with an effortless feel. The inductor mid band has 11 frequencies selected for enhancing individual features or helping tracks sit just right in the mix. The continuous gain knob paired with a boost or cut switch allows for fast “seek and destroy” identification and handling of problem frequencies. The low band acts as a 50 Hz shelf in cut in 3 dB steps, and a continuously variable peaking response with five center frequencies in boost. A separate discrete high pass filter is set for 80 Hz to tame unwanted rumble and can be combined with the low band to deliver powerful, authoritative lows. A second discrete gain stage acts as makeup gain for the EQ, and a discrete Class A buffer drives the line out.  

This style of equalizer has been used on countless records – a testament to its flexibility and musicality for any voice, instrument, or genre.

As with all Iron Age products, the H9 is as discrete as possible, designed and made in the USA.

Block Diagram

User's Manual

HPF 500 Series In +48V +48 VDC GAIN 30 70 60 50 40 -10 +10 0 10 20 0 MIC LINE 80Hz 10k PREAMP LINE AMP -3 -6 -9 -12 -15 LOW 0 30 60 120 250 400 Shelf dB at 50 Hz Hz LOW GAIN -2 -4 -6 -8 -10 +2 +4 +6 +8 +10 0 HIGH MID GAIN .25 .4 .7 1 1.4 2 2.9 3.5 5 6 16 kHz MID Shelf dB at 10 kHz PEAK / TROUGH EQ IN 500 Series out

Technical Specifications

Gain Range

Mic                                                 0 - 70 dB

Line                                              -10 - +10 dB

Maximum Input Level                             

Mic                                               -2.5 dBu

Line                                              +25 dBu

Maximum Output Level                +15 dBu

Input Impedance                                    

Mic                                               1500 Ohms, transformer balanced

Line                                              10 kOhms, unbalanced

Output Impedance                        47 Ohms, impedance balanced

Frequency Response                    +/- 1 dB 20Hz-20kHz

Signal to Noise Ratio                    105 dB

THD @ +15 dBu output                 <1%

Power Consumption                      <120 mA

If we are out of stock and you are interested in owning one, please contact us at:

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