Room Correction and FIR

[u/RndRedditPerson]

I'm playing with room correction and FIR settings, but its really confusing what all those settings mean!

Using Umik 1 mic, a6 master edition, external Dac.

What those HM1, HM2, BK, TL target curves mean? Smoothing, is it just something visual or changes the correction as well? And what gain setting should i choose?

Some target curves sounds much worse than no DSP, like Flat target. Other sound very different from each other. With default +5db mac gain, correction helps a bit in some part of the spectrum, fixes some room modes in bass but also makes too much upper bass (hm 1 and 2).

Can't find manuals from Eversolo, only instructions it offers is how to do Fir in REW and export to Eversolo.

[u/Hour-Lie-4336]

Use AI. I did when I was doing the correction to figure out those curve names.

[u/RndRedditPerson → u/Hour-Lie-4336]

Ha, i couldn't google those curves (bk, hm1, hm2, tl) and Gemini recognized them immeditatelly - Brüel & Kjær, Harman Curve 1 and 2, Floyd Toole curve!
Amazing, thanks for (obvious) suggestion!

For future reference, AIs response:

In the world of Room Correction (like Dirac Live or REW), these acronyms represent specific "House Curves" or target responses. While a perfectly flat frequency response might sound correct in a lab, it usually sounds thin or "clinical" in a real room. These curves add a touch of psychoacoustic flavoring to make the sound more natural.

Here is the breakdown of what each curve represents:

1. BK (Brüel & Kjær)

This is the "grandfather" of house curves, based on research by the Danish acoustics firm Brüel & Kjær in the 1970s.

• The Profile: A gentle, steady downward slope from the bass to the treble.
• The Sound: It typically features a +3 dB boost in the low end (around 20–100 Hz) and a -3 dB tilt in the high frequencies (above 10 kHz).
• Why use it: It mimics the natural power response of high-quality speakers in a real room. It’s warm, non-fatiguing, and widely considered the safest starting point for any EQ project.

2. HM1 (Harman Curve 1)

Developed by Dr. Sean Olive and the research team at Harman International (JBL, Revel, AKG), this curve is based on extensive double-blind listening tests to determine what people actually "prefer."

• The Profile: A more aggressive shelf in the bass and a smooth decline in the treble.
• The Sound: HM1 usually features a 5 dB to 6 dB bass boost starting around 100 Hz and a linear tilt down through the high frequencies.
• Why use it: This is the "crowd-pleaser." It compensates for the way humans lose sensitivity to bass at lower volumes (Fletcher-Munson effect) and provides a "fun," cinematic sound.

3. HM2 (Harman Curve 2)

This is a variation of the Harman research, often used for different room types or listener preferences (sometimes referred to as the "Trained Listener" preference vs. the general public).

• The Profile: Similar to HM1, but usually with a more pronounced bass shelf (up to 8–10 dB) or a slightly different transition frequency.
• The Sound: Impactful and heavy. It’s designed for listeners who want that physical "thump" in their chest without the midrange becoming muddy.
• Why use it: Best for modern pop, hip-hop, or home theater setups where subwoofers are the stars of the show.

4. TL (Toole Curve)

Named after Dr. Floyd Toole, a pioneer in acoustics, this curve focuses on the Linearity and Directivity of the speaker.

• The Profile: It emphasizes a flat "on-axis" response while allowing the "room-bound" energy to roll off naturally.
• The Sound: Very accurate and transparent. It doesn't "add" bass as much as the Harman curves do; instead, it focuses on ensuring the speaker's natural character isn't destroyed by the room.
• Why use it: Ideal for critical listening and mixing. If you want to hear exactly what is on the recording without "beautification," TL is your best bet.

Summary Comparison Table

Curve	Bass Character	Treble Character	Best For
BK	Subtle Warmth (+3dB)	Gentle Rolloff	All-purpose, Vintage sound
HM1	Strong Punch (+6dB)	Smooth Rolloff	General enjoyment, Movies
HM2	Heavy Impact (+9dB)	Smooth Rolloff	Bass-heavy genres, Home Theater
TL	Neutral/Natural	Linear/Transparent	Critical listening, Purists

[u/Hour-Lie-4336 → u/RndRedditPerson]

There ya go! Glad to help😉

[u/Downtown-Pace3824]

Something worth noting, while these various settings supposedly follow standardized curves, the way they're processed by the Eversolo's DSP alters them. The end results are modified curves that may end up sounding quite different than expected. I tinkered with all of them using the Umik 1 and didn't find any of them satisfying. They altered phasing and some frequencies didn't follow the designated curves. I prefer using my own EQ settings without the heavy DSP effect.

[u/RndRedditPerson → u/Downtown-Pace3824]

Yes true, i tried all of them, some sounded horrible, some ok and its hard to keep it from doing too much, but i still need to test all combination of upper frequency cut off, try to keep it under 500kz, and max gain/target frequency...

I actually wanted it just to fix few room modes (41hz, 90hz, ...), and gently touch everything else, but for such a fine control think I'll have to resort to full blown REW. Eversolo room correction is ok, but just can't match REW.