EQ filter to adjust bass-shy and bass-heavy classical recordings

[xandresen]

Do the bass levels of your classical recordings vary too much from one recording to another?
____or maybe in other types of music?
I observe this in my classical music collection, which is what I primarily listen to.
Classical is a big part of voicing the loudspeakers I build.

My recordings are of modern performances, high-resolution FLAC files. Generally symphonies or concertos.
My speakers easily reach down to 30Hz.

A few recordings are very bass shy, not much fun if it's a symphony.
A few others sound like the recording engineer turned up the subwoofer (my system doesn't have one). Fun for a few minutes but not realistic.
And others could be better balanced than they are.

Secret Sauce recipe
I use a miniDSP digital crossover for my 3-way speakers so I started playing around with a bass shelving filter.

If you don't have a digital crossover, some music players can add a parametric equalizer plug-in.
MathAudio.com's "Headphone EQ" has parametric EQ and might work, I have never tried it.

Over a period of two years I refined the bass shelving to this:
Center (turn-over) frequency = 175Hz.
Q = 0.5
Gain : the default setting is Gain = 0 (no effect)
I find that +- 2dB Gain is enough to handle the worst offenders, it makes a big improvement.
Other recordings can benefit from +-1dB adjustment.
The sound balance stays natural.

(note: I originally used a turnover frequency of 250Hz but over time found I was getting too much change in the lower mid-range.)

Finally
Being lazy, I usually only make an adjustment when I play recordings that are extremely off balance (needing +-1.5dB or more of shelving). Wish I could automate setting the miniDSP shelving gain from custom flags in the FLAC files.

[JonMarsh]

Probably an issue just due to too many initial edits.

[Reet]

Switch to a software solution for EQ if you want to be able to auto-load an EQ preset for every song. Regardless of the genre of music, mixing/mastering process to what ultimately get s distributed can vary wildly, especially on older recordings. I swear there are many CD releases where the track made for vinyl was just transferred to CD without RIAA EQ applied.

[tktran]

xandresen

175Hz sounds about right. One professional mixing console that's in wide use has a bass EQ which is effectively a 12dB low shelf at 180Hz, capped at +6dB. for bass EQ.

Feel free to experiment with different EQ too. Depending on your recording, many have passed through analog consoles by the mastering engineer, equalizing to whatever they had at the time.

Now, some of the modern digital recreations of eq. Waves are pretty faithful to the old desks eg. SSL, but sometimes the imperfections of the analog consoles are what gave them their distinct flavor/character. For example, there is one analog EQ (I won't name the brand) but when you turned up the bass EQ, for some reason it created a slight (a fraction of a dB) boost around 7KHz, quite wide too- a Q of slightly less than 0.5.
A tiny bit of treble boost with for your bass boost!

It's this kind of idiosyncratic behavior that give analog consoles/equipment their sound. The analog afficionados are right when they say digital isn't as good as analog- it just doesn't create these special FX!

[xandresen]

tktran
Thanks for the info on EQ in professional mixing consoles! Explains why the choice I came up with would work well across many recordings.

The console that adds a bit of treble to the bass EQ reminds me of the Fletcher-Munson hearing curves. I had a pre-amp in the old days with one knob to adjust both bass and treble (following those curves) so lower listening levels would have the same perceived frequency balance as the original "loud" sound.
Great idea but proved pretty useless in practice - too much variation in recorded levels (record to record) and also in the level I wanted to listen at, so I never knew where to set the knob.
These days I have the luxury of listening "loud" so any EQ will have a more consistent audible effect.

[JonMarsh]

Do the bass levels of your classical recordings vary too much from one recording to another?
____or maybe in other types of music?
I observe this in my classical music collection, which is what I primarily listen to.
Classical is a big part of voicing the loudspeakers I build.

My recordings are of modern performances, high-resolution FLAC files. Generally symphonies or concertos.
My speakers easily reach down to 30Hz.

A few recordings are very bass shy, not much fun if it's a symphony.
A few others sound like the recording engineer turned up the subwoofer (my system doesn't have one). Fun for a few minutes but not realistic.
And others could be better balanced than they are.

Secret Sauce recipe
I use a miniDSP digital crossover for my 3-way speakers so I started playing around with a bass shelving filter.

If you don't have a digital crossover, some music players can add a parametric equalizer plug-in.
MathAudio.com's "Headphone EQ" has parametric EQ and might work, I have never tried it.

Over a period of two years I refined the bass shelving to this:
Center (turn-over) frequency = 175Hz.
Q = 0.5
Gain : the default setting is Gain = 0 (no effect)
I find that +- 2dB Gain is enough to handle the worst offenders, it makes a big improvement.
Other recordings can benefit from +-1dB adjustment.
The sound balance stays natural.

(note: I originally used a turnover frequency of 250Hz but over time found I was getting too much change in the lower mid-range.)

Finally
Being lazy, I usually only make an adjustment when I play recordings that are extremely off balance (needing +-1.5dB or more of shelving). Wish I could automate setting the miniDSP shelving gain from custom flags in the FLAC files.

I can relate to this and the EQ you are using, but note, being an old analog curmudgeon (we won't discuss just HOW old... but some of my better speaker and recording studio work was done in the 70's), I would look at another variation of the passive voicing filter (as first proposed by Sigfried Linkwitz as a fix for the sonics of stereo recordings on his dipole speakers) inserted between preamp and power amp, and just a simple toggle switch to enable or disable. Certainly as a first step to evaluate before considering a DSP approach. No DSP's in my systems anyway, because I could never afford the R2R ladder DACs to run a multi-way crossover! And of course, be sure you have all your room issues and treatments sorted out first... something also learned back in the 70's.

🤪

[tktran]

JonMarsh

I’ve found something affordable that you might consider dipping your toes in, before you invest in 8 channels of R2R DACs:

https://www.minidsp.com/products/ht-series/flex-

probably as neutral and honest as the best professional DA converters used in studios in the late 20th century eg. Prism, Digidesign, Apogee. Of course if you’re looking for DAC to sound like your favourite DAC then it’s probably not your cup of tea.

[xandresen]

I'm using the miniDSP Flex8:
two channel (16 or 24 bit) digital input with EQ followed by 8 channels of [EQ, crossover, delay, gain, etc.], and an 8 channel DAC of newer vintage than their earlier boxes. They claim this DAC is better. There is some online distortion testing by a third party.

The EQ and crossover can optionally be entered as biquad coefficients. So I am currently using a 3rd order Bessel mid-tweeter to mimic a certain JM's quasi 3rd order LR idea.

It may not be the ultimate but given my budget, this unit saves me from paying a fortune for quality crossover components every time I make a change or experiment.

One limit that will put some people off is they didn't increase the processing clock speed from the earlier units. It's still doing 96KHz. wish it was 192KHz.

[tktran]

xandresen

Flex 8 is good enough for me-

[tktran]

Here’s that live performance mixer’s LF and HF EQ: