Iron Age Audioworks LH95 User manual

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User’s Manual
LH95 Inductor Equalizer 

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Thank you for your purchase of an Iron Age LH95 Equalizer. Iron Age Audioworks is a small
team of engineers and designers and we truly appreciate your business. We hope you enjoy
using this as much as we enjoyed making it.
Safety
Safety with audio equipment is normally a matter of common sense, but we want to make sure
you get the best use out of your equipment. So please, use common sense including...
●Use typical practices for using electrical and audio equipment.
●Don’t clean this with water or use it around water.
●Any ventilation openings in the case need to remain open.
●Don’t use this around anything that’s hot (such as a radiator or space heater).
●Don’t defeat the ground pin on the plug or use a ground-lift device that does.
●Don’t use a cut or damaged power cord, and keep the cord from getting pinched or
stepped on.
●Don’t service the box unless you’re a qualified technician.
Power
The unit is compatible with any VPR compliant 500 series rack.
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© 2020 by IronAgeAudioworks 1

Overview
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.
Block Diagram
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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.
Controls
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.
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© 2020 by IronAgeAudioworks 2

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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.
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Technical Specifications
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
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© 2020 by IronAgeAudioworks 3

Frequency Response
Frequency response plots generated from actual data measured from LH95 production unit.
High Band 
Mid Band 
© 2020 by IronAgeAudioworks 4

Low Band 
Low Cut Filter
© 2020 by IronAgeAudioworks 5

High Cut Filter
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© 2020 by IronAgeAudioworks 6

Warranty
We warrant this product to be free from defects of materials and workmanship for a period of
one (1) year from the date of purchase. We will remedy any defect identified within this period
by repairing or replacing the product at our option. It will be your responsibility to pay for
shipping the product to us, and if the product is determined to be defective, our responsibility
to pay for shipping the product back to you.
LIMITATIONS AND EXCLUSIONS. This warranty, and any other express or implied warranty,
does not apply to any product which has been improperly installed, subjected to usage for
which the product was not designed, misused or abused, damaged during shipping, or which
has been altered or modified in any way. This warranty is extended to the original purchaser
only. THIS EXPRESS, LIMITED WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES,
EXPRESS OR IMPLIED, TO THE EXTENT ALLOWED UNDER APPLICABLE STATE LAW. IN NO
EVENT SHALL IRON AGE AUDIOWORKS BE LIABLE FOR ANY SPECIAL, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OF THIS PRODUCT.
If you suspect a defect in this product, please contact us to discuss the problem (it is possible
that a suspected defect could be quickly remedied or due to improper usage).
Call or email us with any issues, to say hi, or share the music you’ve made. We love this gear
and want you to love it too.
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© 2020 by IronAgeAudioworks 7