Theo Verelst Local Diary Page 91

I've ditched the usual header for the moment, I think it doesn't help much anyhow.
This page is copyrighted by me, and may be read and transferred by any means only as a whole and including the references to me. I guess that's normal, the writer can chose that of course, maybe Ill make some creative commons stuff one day, of course I have made Free and Open Source software and even hardware designs available!

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Mar 9, 20:59, 2010

Server still running ?


Back side of the server and the media machine I type this on (wireless) while watching cable TV and a sat channel: from the top of my head: cable, satellite wire,  mains DVI to hdmi extender, 4.5 m smalll to big firewire cable, TOS (digi audio) in and out (and a AES optical link), Quality USB AD/DA converter, 100base-T (bleh) ethernet cable, long usb to synthesizer midi usb, 5 meter usb extender to other synth or memory usb connector.

In the server we have: Gig ether, mains, 4.5 m DVI extender, USB video digitizer to cable and webcam (s-video), extender to small usb cable for cameras (phone), 4.5 m firefire cable, keyboard, mouse, usb to external 320mb Disc drive, sound output cable, tos sound output, mouse charge usb extension cable, additonal external disc, serial cable.

Additional connections: fpga boards (parallel, serial, usb), dsp boards (serial, midi)., additional (Lexicon) Usb convertor (needs to heat up and isn't reliable at the moment), midi converter cable, additional monitor (VGA) cable.

In fact I tried a 11.5 meter extension on it to a small room to watch sat-tv without the noise and in another room, with a long DVI extender, a double USB extender for the keyboard/mouse receiver and a long TOS digital audio cable (for sound, connected to the Lexicon converter). Works cool.

The media machine currently works on Fedora 12/64, running from a newly installed TeraByte SATA disc from Western Digital, a nice "green Caviar" type (mostly ext3/4 filesystems) which is already almost full with my HD video recordings (over 22 hours at 25mb/s equals about 250 MB) programs, 24 bit (actually 32) audio, programs andrecorded sat/TV, mainly High Definition (BBC HD / ITV HD). Some good films in HD, like Jaws.

Server statistics for the last year:

About 40 thousand hits per month, mostly, but the peak and probably some other traffic was from wiki spam robots. I blocked most of those fully from the system (they don't get any signal back anymore).

The above Linux page being put on the Linux Audio Wiki I think was responsible for the increased traffic.

More PC3 sound developments

Some of my latest analog type of synthesizer emulation sounds:


(Careful with the volume, but have party when playing it with a big powerful system)

Microphone Recordings of Main Audio System played back on itself

That's a crazy experiment!?
Well, an example to hear for yourself (use a good audio system!):  Mike Stern Play # 4.mp3. Recorded at a few meters from the speakers, no compensations, no eq or filtering, straight AT2020 plugged in the Lexicon Omega phantom powered mic preams, of which the insert output is linked to the Lexicon MX400 analog input, which digitized the result to a 24 bit TOS 44.1kC/s signal which is straight converted to the mp3. No tuning, not even measuring the distance between the mic and the speakers, ad hoc as-is recorded.

This is my voice and a cup, with a little effect on the signal IIRC (compression/reverb), see picture below:


(beware, there is an attempt to make noises here, I didn't know I was going to put the stirring example on the internet, burp is audible....)

First I for the occasion madean Irish coffee (more or less, no whipped cream) with like a tiny amount of wiskey, ad recorded my voice and sound of stirring it from 2 diffewrent angles / distances.

Th two lexicons (the top one for excellent spec-ed pre-amps and the lower (19" rack) for the excellent 24 bit AD converter (better than most other equipment by quite a bit at least some yeasr ago):

The screen shows Rosegarden on Fedora 10/64 (my Fedora 12 like on other screen pictures has a problem with the TOS input and alsa, output works though).

Playing around I was varying frequencies from over the spectrum (but some trianglish wave with spikes it appears) recorded with the AT2020's at a listening position, so way too far for correct measurements even in a room with quite some damping (see the left/right interference patterns make for quite different L/R responses, and the high is damped), freqs aren't low to high but change abnd band switch (becasue of the generator program, which I started rather at random):

The 4 band eq is a quality one which I can use for compensating few dBs here and there for the AT2020s characteristics (the graph of it's response is in the manual).

I've made some Linux experiments available here (the connection was the linux audio conference).

Example audio: mandokotopadcabijam690_6c.mp3 (about a minute, 256kbps mp3, stereo, 48k.)

This example takes an impulse revern of a space (concert hall) and one of a cabinat (if I remember correctly) adds that effect to two simulataneous instrument sample sets in LinuxSampler (Gigasampler) and a synthesier simulation, with the special part added that a mastering effect s used to like a PA system feed back the signal from the reverberation to the point of a little less than feedback (like micrphones), so that a "live" amplification feel comes in the signal.

Pretty heavy effect, and musically usable.

Mixing analog Master-HD (DTS) and 24 bit (Pcm) reverb signals

Xmms (winamp on Linux) 30 Band (1/3 oct.) Equalizer

Studio quality? Well sure for limited purposes, I might turn this into a LADSPA or Jack plugin to use seperately, or even a Cuda based effect, because these are well tuned Infine Impulse Response filter, in other workds "normal" ones except of course the highest bands will have sampling issues I'm pretty sure.

But I got some nice CDs legally (but very cheaply!) bought with a lot of uncompressed and not destroyed-mastered great music, which can be compensated for slight recording/mastering curves this way very accurately, which is cool. Speakers and amps sound even better this way!

AES Lecture Tube amplifiers

Radio Shack Catalogs!


Quadro man, great! What a power. And 4 -tacks recordable on a tape recorder in addition to that, for under a $1000,-, well well.

1970 (!):


They had TTL chips normally available in the early 70s, that's cool.