Theo Verelst Local Diary Page 99

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Aug 28, 02:57, 2010

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The Duke heritage

I got 4 CDs from LA (that sounds interesting, ordered from his site..) with 6 ot 7 of the George Duke 70s funky albums on them, digitally remastered in 24 bit, and am very glad with them.

I used to be somewhat of a Duke fan (how many keyboard-synth-piano player who advanced the Funk are there anyhow!) back in the end 80s, when I was practicing for bands and Jazz, and I´m sure he influenced me and others to play decent, and good, and search for the right synthetic sounds instead of a synthetic pointless endless sea of meaninglessness and to honour the better (Jazz) session player rules.

These CDs aren´t as "clean" as some 24 bit Cheskey/HDTracks recordings I can use as reference, and not the same style as quite a few neutrally mastered popular CDs from over the years I use, but interesting and alive, very well sounding, but I think either the format or the remastering studio limits do not do total justice to the great 70s sound as I think of it, even though the sound is interesting and full.

Every self respecting funk pianist cannot afford not to know some Duke, but this is more than some, so I´ll go over the songs a few more times before feeling into that groove...

High Quality General Audio Monitoring

Urges to create flyers, mr. theover ? Not really except I could, my system has been double checked lately because I can now use a good AKG K271 mkII headphone set to compare my monitoring/HiFi/small PA ausio system with.

And that come out great, they actually sound alike. That is proposterous to say, I know, but true enough, though still being further tested, which is of course a self-compliment, and great.

It´s mainly used with my preamp which can drive the headphones, and has extremely good specs (distortion orders of magnitude less than most equipment).

This machine I often (but not always) use as digital output machine, being DA converted by the below Lexicon MX400, and then then preamped to the headphones, with short low impedance wire.

What a quality brand components, in a way that´s fun, because it works.

Of course the headphones and speakers cannot just be randomly compared, so I tested mainly the speakers listened to at the sweetspot, the well known equal sided triangle, listening with the mid-high tweeter at ear-hight. There more than some damping in the room, probably 2/3s of walls and ceiling are damped, even though there are still clearly early reflections, slight bass-buildups (but ever so not intruding) and of course some remaining speaker corner bouncing waves, but still putting on a disco or rock song (I didn´t try much jazz yet) and making the volumes well comparible and the 3 frequency bands of the 5 way monitoring system I built including the 15 inch sub (no bass-reflex anywhere in the system) well balanced the not so probable is true enough: the sounds are comparable, by and large over the while frequency range.

The headphones also thusfar give nice effect impressions when added to musical instruments or audio recordings, as of course they should. Probably it´s a good idea to use a rumble filter (30 HZ or lower) on them, because the bass end I think works neutral that way, and is probably in the lowest range not comparable to whooping woofers of the large kind, which is fine: under 20 Hz cutoff filter on is not bad for the main monitoring either: many materials won´t do much work at 20 Hz anyhow, and most normal stereos and other systems get not much volume done at that frequency anymore anyhow. I mean my sub can get a serious few hundred watts (more peak, it may have up to 500W) when needed to make only the lowest octave from 20Hz to 40Hz audible with it´s large 15 inch cone and a damped enclosure of over a 100 liters. Most people will not be used to that idea. Yet for loud rock, it might be the human hearing cannot be served at more than the equivalent of mayb 110dB-loudness corrected...

15 way Multiband Audio Compression

Compression is the reduction of dynamic range that takes place on many produced audio materials, and in the history of the modern music has been one of the many used tools, also to create a certain atmosphere in a production of track. Multiband compression is more advanced and does the same dynamic reduction  (soft sounds louder, and loud sounds more moderate in comparison with uncompressed) but then with different controls per frequency band.

Probably it should be considered usual to have some bands of muticompression on the radio, and I know in PA systems 3 or 4 way multiband limiting/compression occurs. Of course in these days fft based effects can be used to make a bit different method of dynamic range reducion (I experimented with Jamin, see previous pages which is in fact good at that) but I prefer to not mess with the signal in that way (add considerable harmonic and other distortion in spite of the initially smooth sounding result, and also tends to get boring).

I thought I´d go for a bit more ambitious approach and try a 15 band compression signal path, which I made on Linux, on a not so new but potent enough machine (3GHz Pentium D), using jack-rack as building block.

I made 15 jack-racks with an equalizer followed by a stereo compressor, where each of the 15 audio programs has only one frequency band slider of the eq to 0 (no attenuation or amplification, and probably no resonance centered at the band frequency), and all the other sliders to -60 dB (1/1000th of the amplitude !). The compressors gradually have faster settings for higher frequencies, and have mostly  per frequency band relative loudness related threshold and compression factor settings.

All the 15 stereo filter+compression with 32 bit (floating point per channel) audio processing rack units are connected up in parallel by an automated startup shell script (tcl) whic puts the connections in place, and also starts a 15 wide meter bridge (left+right channel per frequency at the outputs of the compressors), and  creates a input and output rack with additional effects, like so:

"system" is the computers audio IO.

For instance I used xmms (a sort of Linux winamp) with a good working 31 band eq to feed the whole mulitband compression chain, and also I put the Lexicon MX400 in the loop, playing CD files on the whole:

Works great to make the audio fuller sounding (even though of course a lot fo CD might better be dynamically expanded instead of compressed, which they already are..).

The above "ingenuity" application shows the graphical connections more clearly.

I mades some test microphone recordings (with Audio Technica AT 2020s), and synthesizer recording with somehow the above in the audio path (or in the added effect path):


In fact I´ve even made a mulitchannel compression-distortion setup, with seperate tube sound effects per band, and the HD Sat broadcast from Bon Jovi on the Itv I´ve enhanced and reverb-wise un-killed bu using that and speaker simulations on certain bands...

Processor use ? Using the 15 band setup and "Calf" stereo compression and additional non-linear effects takes about 50 percent of the processors ability, on the centrino due 1.83 notbook I use with Linux (and for the time fastest available 750 MHz FSbus), about the same, without having to set the processor speed to maximum, and even including some additional reverbs (not per band).

With many hundreds of slider controls, it can be handy to use Xwindows´ multi screen feature (4 screens on a virtual turning cube):

The Lexicon MX400 (which is a double and surround effect with 2 stereo in and outputs, also able to do 4 effects simultaneously), digitally coupled, agrees very very well with these sort of signal chains, and appeats happy and well able to do its magic anywhere in these signal paths.

In fact I even experimented with a gated feedback loop with the Lexicon and the multicompression in the loop, applied to early Elvis recordings and the very good "Last Man Standing" CD from Jerry Lee Lewis, which with the right settings (even close to feedback of the loop, and sometimes unstable because of the combined gate/compression) can get me those mesmerizing Lexicon and live effects I want, and even fill a neutrally recorded Cheskey track with great ambiance, of the grand kind. I´ve also added 3 different reverbs, additional filtering, and allpass filtering, which is great with the tube "feedback" sound.

More on this later, I´ll make some examples.


An equalisation with connected multiband compression tuned somewhat to the components in a E chord.

This effect has side effects, so I often use it in parallel with a delay line mixed wit the result coming from the same source, set to the average delay of the effect (tuned with the "jet engine" sound when a broad spectrum sound is used set to maximally audible high frequencies and least profound and most symmetrical group delay based comb-filtering).

Want to see Bond, James Bond movies?

I think I got the majority of them in High Definition quality (with the actual HD logo, not jut good quality) from the satellite receiver-computer I use, courtesy of the british ITV.

Is that hard to watch, HD? I do it a hard enough way, with a computer with originally just a sat receiver but with fast enough interface to read a whole sat stream with all substreams, a graphics card double h264 accelerator, Linux, and mplayer, and a lot of controls for colours, optimisations for VDPAU and such.

I recently tried how long it took me to download, configure, compile, and test-run a completely fresh mplayer from the source repository, on the Fedora 12/64  Caviar green 1+1.5 TeraByte, Pentium D, sat receiver, NVidia Cuda capable 9500 graphics card Linux machine I use every day for watching TV (and more): 16 minutes!

Cool. And it works in practice, and some good films already.


I tried the almost latest posgresql and it works, and so does the latest media wiki, but this is tryout, not on the server machine.

I tried this too.

A new domain name provider

From now on, the cool remains visible in the address bar of the browser when you click links: no more ip address numbers.

Also there another server on (no www.) where I can store files up to a gigabyte for faster download than the server which I run myself over a ADSL line. Example:

that´s a video I´ve made about linux sound programs (complicated ones) to use with a streaming 720HD media player.

Can more processing power be bought ?

Lets say an i7 with fermi-capable 2GigaByte graphics card with actual HD screen, and 4 GB memory and Bluray player and even windows 7, as a notebook:

well well...