IGS Audio 825EQ – Stereo Tube Mastering Equalizer
 
The IGS Audio 825EQ is a five-band stereo tube equalizer for mastering, mix-bus processing and tonal shaping on individual sources. Its dual-mono design combines stepped ELMA controls with three tubes and three audio transformers per channel, offering repeatable settings and a hands-on analogue workflow.Inspired by the EAR 825 tradition, the 825EQ pairs low- and high-frequency shelves with three bell bands. Shape the balance of a complete mix, adjust the weight and presence of stems, or refine vocals and instruments. Both ±6 dB and ±12 dB versions are available to order from Falkenstein ProAudio.
 
Five bands for flexible tonal shaping
 
Each channel provides five bands with selectable frequencies. The shelving bands adjust the overall bass and treble balance, while the three bell bands address body, presence and upper-frequency detail.Overlapping frequency options let you approach different aspects of the same region. Combine a low-shelf adjustment with a low-mid bell to shape bass weight and definition, or use the upper bell and high shelf to distinguish presence from a broader treble lift.
 
Selectable frequencies:
Low shelf: 20, 30, 60 and 100 Hz.
Low-mid bell: 60, 120, 240, 500 and 700 Hz, plus 1 kHz.
Mid bell: 1.5, 2, 3, 4 and 5 kHz.
High-mid bell: 6, 8, 10, 12 and 16 kHz.
High shelf: 3, 5, 10 and 20 kHz.
 
Proportional Q: bandwidth follows the adjustment
 
The 825EQ uses proportional-Q behaviour, with a specified Q range of 0.3–6. Rather than offering a separate bandwidth control, its filter response changes with the amount of boost or cut. Smaller adjustments act broadly, while stronger adjustments become more focused.Choose a frequency, adjust its level and listen to how the tonal balance develops. This approach suits engineers who prefer shaping a connected EQ curve rather than adjusting frequency, gain and bandwidth independently.
 
Choose the ±6 dB or ±12 dB version
 
The boost/cut range is specified when ordering. These are separate configurations, not switchable ranges within the same unit.The ±6 dB version suits restrained tonal adjustments and final mix balancing. The ±12 dB version provides additional boost and attenuation for more pronounced shaping on mixes, stems and individual tracks.Select the range that matches your workflow, and confirm your preferred version and current lead time before ordering.
 
Stepped ELMA controls for manual recall
 
Stepped ELMA switches provide defined positions for documenting settings, comparing adjustments and matching the two channels. This is particularly useful when moving between projects or returning to an earlier mastering session.Recall is manual: the 825EQ does not provide plug-in automation or automatic DAW session restoration. Record the switch positions on a recall sheet or in your session notes, then restore them when needed.
 
Three tubes and three transformers per channel
 
Each channel uses three ECC88 tubes together with input, interstage and output transformers. UTM transformer-balanced inputs and outputs, including a gapped interstage transformer, form part of the analogue signal architecture.Tubes, inductors and transformers contribute to the unit’s behaviour, but the audible result depends on the source, signal level and EQ settings. The 825EQ offers analogue tonal shaping without requiring every adjustment to produce obvious saturation.IGS also lists alternative tube sets, including E88CC, 6N23P and 6N1P-EV. Please confirm available factory options before ordering if you require a particular configuration.
 
EQ bypass keeps the analogue path active
 
The 825EQ provides independent EQ switching for each channel, but it does not have a hard-wire bypass. With the EQ section switched out, the signal still passes through the tubes and transformers.This lets you compare the contribution of the EQ curves while retaining the active analogue path. To compare the complete unit against an unprocessed route, use suitable external insert switching or routing.
 
Dual-mono flexibility for mastering and mixing
 
Both channels have independent controls. Match their settings for conventional stereo processing, or use them separately for two mono sources or deliberately different adjustments.On a stereo master, the shelves provide broad tonal balance changes while the bell bands address specific areas of weight, presence and definition. The same layout can be applied to mix buses, stems, vocals and instruments.For hybrid production, connect the 825EQ through suitable line-level converter outputs and inputs. Document the hardware settings alongside your DAW session for a practical recall workflow.
 
Balanced connections and an internal power supply
 
Two balanced XLR inputs and two balanced XLR outputs connect the 825EQ to converters, patchbays and analogue studio equipment. The unit occupies 3U in a standard 19-inch rack.An internal linear power supply supports 115/230 V mains operation, with no external power-supply box required. The specified maximum input level is +22 dBu, with a maximum output level of +26 dBu—useful reference points when setting levels through a hybrid processing chain.
 
Is the IGS Audio 825EQ right for your studio?
 
The 825EQ suits engineers looking for a five-band tube equalizer with independent channels, stepped controls and proportional-Q behaviour. It combines broad tonal adjustments with more focused shaping in a direct, hardware-based workflow.Its design prioritises hands-on operation rather than digital control. Choose it for manual recall, flexible tonal shaping and an active tube-and-transformer signal path—not for automatic session restoration or complete hard-wire bypass.
 
Order your preferred configuration
 
The IGS Audio 825EQ is available to order from Falkenstein ProAudio in both ±6 dB and ±12 dB versions. Confirm your preferred boost/cut range, any requested factory tube configuration and the current delivery estimate before placing your order.

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