The HO2 is a dual-channel preamp aimed at stereo recording and two-track capture.
Studio Rack
HO2 All Discrete 2-Channel Mic Preamp
A two-channel all-discrete mic preamp built for clean but vivid recording on piano, vocals, acoustic guitar, strings, and other stereo or dual-track sources.
2 Channels
All-Discrete
5 dB Steps
Fine Trim
Optional Permalloy Output
Why It Matters
Four things that define the HO2
That phrase sits at the center of how the unit’s sound is positioned.
Internal notes describe 5 dB stepped gain with an additional fine adjustment range.
The product copy highlights additional colour options including a permalloy output transformer.
Workflow Reference
Use it as a matched stereo front end before turning it into two unrelated channels
HO2 shines when the source needs two channels that stay coherent, open, and alive — piano, acoustic instruments, vocals, and any stereo capture that should feel natural first.
- Stepped Gain Then Trim Set the big decision first, then fine-tune the last few dB.
- Stereo Consistency Matched dual-channel behavior is part of the reason to choose HO2 in the first place.
- Character Is Optional Start with the clean vivid path, then decide if the optional transformer colour is actually helping.
Quick Start
How to start without losing what makes HO2 useful
-
1
If the source is stereo, begin with both channels treated as a pair so the image stays believable.
-
2
Use stepped gain to get close, then fine trim to align the final level more precisely.
-
3
Engage phantom only when the microphone requires it and stay careful around ribbon microphones.
-
4
If the left and right channels feel mismatched, check mic placement and source balance before blaming the preamp.
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5
Write down stepped and trim positions once the source lands in a repeatable sweet spot.
Start simple, listen in context, and save only the settings you would actually want to recall.
Working Uses
Where owners usually find HO2 paying off fastest
A natural fit when stereo realism and consistency matter as much as gain.
Works well when the recording should stay open and vivid rather than aggressively pushed.
Useful when transient life and low-noise gain both matter.
One of the clearest reasons to choose this preamp over a single-channel option.
Working Notes
Notes that help a two-channel preamp stay consistent across sessions
HO2 becomes more valuable when the pair behaves like one image tool rather than two unrelated channels.
Small trim differences can matter more than people expect once the source is panned or captured as a stereo pair.
If the channels feel uneven, compare source position and microphone angle before suspecting the electronics.
The payoff can be confidence and depth rather than obvious colour. That still counts as character.
On a two-channel front end, a simple note about which side used phantom can save time later.
Recall becomes easier when you record the mic pair, spacing idea, and intended image, not just gain positions.
Specs
Key Specs
Gain Range (Mic Input)
10 - 75dB
Z&H Trim Range
-5 to +5dB
Gain Range (Hi-Z Input)
N/A
Maximum Output Level
+26.5 dBu (100k Ohm load, 0.1% THD)
VU / LED Thresholds
Green: -14dBu · Red: +24dBu
THD+N
@20dB gain: <0.005 · @40dB gain: <0.008 · @60dB gain: <0.048
IMD
<0.021
Equivalent Input Noise
< -95dB for both 200KΩ and 600Ω sources
CMRR
41.4dB at 400Hz, 1kHz, 10kHz
Phase Deviation (HPF off)
>4 degrees from 50Hz to 25kHz
Frequency Response
-3dB: 4.5Hz - 390kHz · -0.5dB: 10.5Hz - 140kHz (Mic Input @ 40dB Gain)
Impedance
Mic input 1.7kΩ · Ribbon mode 1.2kΩ · Output balanced 600Ω / unbalanced 400Ω
Unit Dimensions
4.3cm x 44cm x 26cm
Unit Weight
4.8kg / 10.58 LB
Power Consumption
100V - 240 V AC, 50 Watts Max
Owner FAQ
Questions that usually come up after the first stereo session
Phantom Should phantom be enabled by default on both channels?
Only when the connected microphones actually need it. Dynamic mics usually do not, and ribbon microphones should be approached with extra caution.
Treat each channel according to the microphone on it, not according to habit.
Matching Why do the two channels sound uneven?
Check source position, mic placement, and gain matching first. Stereo capture problems often show up before true preamp problems do.
It is very easy to blame the electronics for what is really a placement problem.
Gain What is the right way to use the stepped gain and fine trim together?
Use stepped gain for the big move, then fine trim for the last alignment step. That keeps the workflow fast and repeatable.
Trying to do everything with one control makes matching harder, not easier.
Tone Is HO2 supposed to be coloured?
Its main identity is clean but vivid. Extra character should feel optional, not mandatory on every source.
If the recording already feels alive and believable, that may already be the right answer.
Use Case When would I choose HO2 instead of V12?
When stereo consistency, lower-key elegance, and acoustic-source realism matter more than a more forward single-channel punch.
This is one of the clearest splits between the two preamp directions.
Recall Why keep notes on a preamp that seems simple?
Because matched stereo recording depends on repeatable gain structure. Step values, trim, phantom state, and source notes all matter later.
The simpler the front end looks, the easier it is to forget what actually made it work.
Recall What note makes HO2 recalls better than just gain positions?
Write down the microphone pair, placement idea, phantom usage, and what image the pair was supposed to create. That usually matters more than the gain numbers by themselves.
The preamp is only one part of why a stereo capture worked.
Downloads & Resources
Keep the key files and working tools in one place
Use the shared Setup Sheets library for now.
WIP: Dedicated setup sheet pending.
Open LibraryOpen the shorter operating guide when you need a fast setup reference without the full manual.
Open PDFUse this page for first-session workflow, quick specs, and owner FAQ while the session is live.
Open the downloadable manual when you need a formal control reference or an offline copy outside the guide.
Open PDFUse the support page when the issue moves beyond normal workflow and starts looking like routing, power, noise, current draw, phantom, or service.
Open SupportService
What to have ready before you reach out
Microphone Context
List the microphones, phantom state, and whether the issue appears on one or both channels.
Stereo Context
Mention whether the source was stereo piano, dual vocal setup, guitar pair, or another matched recording task.
Control Context
Include both stepped gain and trim positions instead of only saying one side felt louder.