AI gave me this:
When you’re pairing a Audalytic HP70 preamplifier with adjustable gain and an Audio by Van Alstine Vision SET-120 power amp, there isn’t a single magic number for gain — it depends on your speakers’ sensitivity, your source level, listening environment, and how loud you like it. But I can absolutely walk you through how to set it up so it performs its best. 🎶
🎛️ What “Gain” Means Here
The adjustable gain on the HP70 scales the signal level going into the Vision SET-120. Too low → quiet with limited dynamics. Too high → distortion and noise floor issues from the SET.
Since the Vision SET-120 is a single-ended triode (SET) amp, it likes healthy signal levels without clipping. SETs generally sound best when driven with a good, clean signal.
✅ Goal for Gain Setting
You want the preamp’s output to:
✔️ Be loud enough that typical listening is comfortable without maxing the preamp volume
✔️ Avoid overdriving the Vision SET’s input stage
✔️ Let the HP70’s volume knob have good resolution (not too finicky)
🔧 How to Set the Gain (Step-by-Step)
Start with the HP70 gain at its lowest or unity (0 dB)
If it’s labeled numerically (e.g., –6 / 0 / +6 dB), start at 0 dB.
Play a familiar track at a normal listening level
Choose something with a wide dynamic range.
Turn up the HP70 volume to where you’d normally listen
Note if you’re near maximum rotation or if the sound seems weak.
Listen for distortion or compression
If the amp sounds strained at comfortable listening levels → reduce gain.
Adjust gain upward only if needed
If you have to crank the HP70 to near full for normal levels, increase gain in small steps and repeat listening tests.
🎚️ Typical Starting Points
Although every system and taste is different…
Situation Recommended Starting Gain
High-sensitivity speakers (95 dB +) Lowest or unity gain
Moderate sensitivity (~88–94 dB) Unity to +3 dB
Low sensitivity (< 88 dB) +3 dB or more (careful!)
Most people end up around unity to +3 dB with SET amps. If your preamp has finer increments (like 0.5 dB steps), aim for the smallest boost that gives you happy listening levels.
🔊 Tips for Best Sound
🎧 Match source output
Some sources (especially digital) have low line-out levels. In that case, a bit more preamp gain is justified.
📏 Check noise floor
SET amps can reveal noise. If raising gain brings hiss or hum forward, back it off.
🛠️ Use your volume control effectively
Ideally the preamp gain sets the baseline, and the volume knob gives you fine adjustments — not the other way around.
🧠 A Simple Rule of Thumb
Set the gain so that your normal listening level sits around the middle of the HP70’s knob range — no near-max turns and no distortion from the power amp.
I hope this helps.
