[sdiy] stringfilter (NEW INFO, NEW DEMOS !!!)

[Kenneth Elhardt]

Jeurgen Haible writes:

>>(Seriously: Ken Elhardt's string sounds are more convincing than my demos,
and he used a handful of readily available FX boxes. Maybe he likes to talk
about that)<<

Hello JH.  I'm weeks behind on catching up on e-mail and posts so I'm just
seeing this now. I realize I probably appear as if ignoring people but I'm
just busy and really tired of the internet in general. I'll be catching up
in a few days I hope, but I can tell you everything you need to know about
string filtering and have a few new mp3 demos of my Nord 40 bank string
filter in action.

Too time consuming to cut and paste questions, I'll just answer them. Using
equalizers for the job? They don't work. I also have that Behringer 24 band
feedback surpressor. The sound will still sound synthetic, just filtered
differently. No EQ has enough bands anyway. You need about 4 to 6 peaks and
4 to 6 nothches per octave. A 31 band EQ only has 3 bands per octave, which
only allows 1 peak and 2 notches or vice versa. Nor are they as steep and
drastic as needed. JH could have mentioned some of the stuff I use as it's
no secret, such as delay lines and phase shifters as comb filters. But I'm
trying to get away from them because I have no control over how the peaks
and notches are placed within something like a 40 stage phaser. And the
metalic sound that delay lines create makes me have to use many in parallel
to randomize the frequency response, and again I have little control over
where those peaks are.

I've actually done some high count multiband filtering on my Nord before.
One demo I put up is the following showing the effect on an the unprocessed
sound. Actually it's part multiband filterbank and phasershifter. I don't
think something like the Moog string filter gives such a dramatic change to
the sound.

Filesize 200,622 bytes:

http://home.att.net/~elhardt3/String_Filtering_motm.mp3

As for my latest experiments below, I'm using my Nord Modular as sound
source and to also process its own sound (I'm plugging the output of the
Nord back into itself to process itself since I need the power of three DSPs
just for the filter bank). I've tried many different configurations, such as
6 bands per octave (every other semitone), 4 per octave, alternating
spacing, random spacing, and so on. The best overall sound was alternating
between 2 and 3 semitones for about the first 24 filters and then
compressing down to 2 semitone spacing higher up. This produced the most
wood-like tone, while not sounding too hollow, too synthetic, or all kinds
of other problems I've come across. I'm then running that through a
Behringer 31 band True Curve EQ to shape the overall sound for a more
refined sound.

Also the source sound you create to run through the filter bank is
important. Just using a sawtooth oscillator with vibrato is too organ-like.
I'm using several delay lines slowly sweeping around kind of as subtle
choruses (also used this on my older string sounds), and they act as
harmonics animators. If you've ever looped a single cycle of an acoustic
instrument, it just sounds like an electronic tone because there is no
motion. This also makes the vibrato sound sweeter and more string-like. You
also want if possible, randomization of note pitch as fretless violin notes
are always somewhat out of tune. You need human-like vibrato, changing in
speed and depth. You need control of the string loudness and tone after the
key is pressed so you can phrase it the way a string player would. I'm also
using a Nord waveshaper module that adds some high freq harmonics for a
brighter more scratchy sound which really helps bring out the buzzy top end
of the cello, and I can modulate it if I want bownoise. If you want to play
fast notes, you'll want some kind of bow slipping/scraping sound on the
attack. And when I move my string source sound to Reaktor, I'll add the
little portamento slides that really help (can't get to sound real on the
Nord for some reason). In other words you have to really losen up and get an
animated sound. Organ type sound in, organ type sound out.

Filter plot of white noise running through my string filter:

http://home.att.net/~elhardt4/String_Filter_Plot.jpg

(Note that these demos should be heard through good quality highly detailed
headphones to hear all the subtleties. I'm often shocked by how the
beautiful tone and highend detail can disappear when played through other
means.)



Here are some new demos. This one alternates between my warm and fuzzy
newage Nord violin and the real one in this Ackerman recording. I had to
splice in solo guitar parts from the beginning of the piece, thus some
obvious sudden edits. The timbre of the two is quite close just using my
default filterbank band placement, so much so that with just a little effort
in playing/phrasing and timbre adjustment I could probably replace the real
violin in the entire piece and few would notice the change. Following is the
timing of what is real vs Nord in the recording. Also threw in a Nord cello
toward the end, really showing off the wood-like quality of the filterbank
as the virtual bow scrapes across the last cello note.

0:00 to 0:22 Nord

22:00 to 0:38 Real

39:00 to 0:58 Nord

1:00 to 1:16 Real & Nord playing together

1:12 Nord cello enters, all Nord through to the end

Filesize 1,801,370 bytes:

http://home.att.net/~elhardt4/String_Filter_Violin_Compare.mp3



Here is a snippet from the Brahms violin/cello concerto. First take is with
the real cello, second take is the Nord. Because my bands aren't in same
places as the real thing there is a timbral difference (if I can correct,
will be a near perfect match), but in the low end you will see that the
cello-like characteristics of the Nord sound almost every bit as much like a
cello as the real one, just with a different body timbre. Needs more work in
the higher range to get that sad/whiney/stringy cello type sound.

Filesize 541,641 bytes:

http://home.att.net/~elhardt4/String_Filter_Cello_Compare.mp3



One pitfall that I've encountered is when using the same string filter for a
ll the instruments in an ensemble. I did one recording I didn't even place
online because the entire orchestra sounded like it was playing through a
tin can even though the individual instruments sounded pretty good by
themselves. When I thought about it I realized that they were all
emphasizing each other. Where as in a real orchestra, different instruments
have different frequency responses and they smooth and average each other
out. This is just one more reason to do it digitally where you can change
filter settings unlike a fixed analog filterbank. None-the-less I tried to
do a number of things differently to minimize that bad effect in my
following Bach performance of a small up-close chamber group (with sampled
harpsichord). Still it's a quite resonance sounding and badly distorts and
sounds like total crap in many other ways through computer sound systems.
Needs to be played through something that can handle severe resonances
popping out all over the place, such as quality headphones. Even there,
there were some problems, such as the popular Sony MDR-7506 which sounded
ear-piercingly nasal in the 2K to 4K range. If using those, or others with
the same problem, listen to the second file labeled (Sony). If using
Sennheiser HD-280, AKG K240, Fostex T50RP (needs treble boost if possible),
or most others, try the first one labeled (Senn).

Filesize 809,553 bytes:

http://home.att.net/~elhardt4/Nord_Baroque_Strings_Senn.mp3

http://home.att.net/~elhardt4/Nord_Baroque_Strings_Sony.mp3

---------

Just a couple of demos using my older methods for those who don't know what
I was talking about. This string orch uses delay lines and a phaser.

Filesize 439,382 bytes:

http://home.att.net/~elhardt3/String_Orchestra_Nord_160.mp3



All the sounds in this one are from analog or virtual analog synths. Violin
and cello use delay lines, the Andromeda guitar sounds use a phaser for nice
body resonance. BTW, filter banks are good for other things too. Just in my
fooling around I've gotten complex timbres that sound like pianos, harps,
sitars, bagpipes, and big organ pipes, that don't sound like anything you'd
normally get from an analog synth.

Filesize 881,478 bytes:

http://home.att.net/~elhardt3/Acoustics_192.mp3



-Elhardt