EML-101 Multimode VCF Schematic

via Aaron on the sdiy list:
"One project idea that I tossed out to my students, which one student is trying to get work, is to use the idea of an NPN differential amp driving a "differential integrator" to build a 1-pole LPF, which you could then do four times to get a usual 4-pole LPF.

I got the idea from the EML-101 filter schematic [mirror], as expertly redrawn by Marjan Urekar:

The EML-101 is a state variable filter, and said diff amp/diff integrator configurations form the variable gain integrators.

My thought was that we could take the output of such an integrator, and feed it into the opposite input terminal of the diff pair, and that feedback should form a 1-pole LPF, as follows:

The NPN pair driving the differential integrator forms a variable gain integrator with transfer function A/RCs, where A is the voltage gain of the diff pair and R and C are the resistor values used in the integrator. Let's denote wo = A/RC. Now imagine we take the output of this integrator and feed it back into the input with a minus sign. You get something like this:

Y(s) = (wo/s) [X(s) - Y(s)]

Y(s)[1 + wo/s] = (wo/s) X(s)

Y(s)/X(s) = (wo/s) / (1+wo/s) = wo/(s+wo)

Which is the transfer function of a single-pole LPF with cutoff wo with unity gain at DC. (This is the same idea as a usual OTA-C filter 1-pole LPF).

Three questions:

1) I sent my student, Justin, this sketch to get him started, where I just blindly ganked the resistor and cap values from the EML circuit.

Anyway, I just realized I drew that wrong - the EML integrating stage is _inverting_, so we should actually either:

A) Swap the inputs on the differential integrator, to make a noninverting stage, or

B) Take the feedback to the left NPN instead of the right NPN

Does (A) or (B) sound like the safer option?

2) Given the way the "differential integrator" is going to load the differential amp, should I even be thinking of this as a differential amp followed by a differential integrator? Or are they interacting so much such thinking breaks down?

3) Does this whole crazy idea of mine sound like a decent idea at all or is it doomed to insanity?

- Aaron

P.S. This got me wondering if there's an "integrating version" of the standard 3-op-amp instrumentation amplifier? A differential integrator with high input impedance, but something more elegant than just slapping noninverting op amp buffers at the inputs to the above differential integrator?

http://en.wikipedia.org/wiki/Image:Opampinstrumentation.svg"

Switched-On-Rock

flickr by mpeake

full size

Page 2

SCSI for Samplers - Flash Drive for Your Sampler

"Do you need a better storage method for your data than the unreliable zip drive or the slow floppy drive? Card Reader drives are the new state-of-the-art storage solution - stop worrying about when your zip drive will fail or how many boxes of floppy disks you will need to save your latest sample. Now you can have as much reliable storage space as you need with inexpensive Compact Flash cards.

The MCDISK-2 is a solid-state Media Card drive that has no moving parts and makes no noise during operation. It comes in a small beige case that is 8.5" x 6.75" x 2.25" and can be used in any orientation, flat or on its side. It is very sturdy and solid, equally at home on the road or in the studio. This case has a fan in it but we ship the drive with this fan disabled in order to keep the unit completely noise-free. The fan is not needed in this configuration because the internal MCDISK drive puts out no heat at all and the internal power supply puts out only a very small amount. The case stays cool internally from natural air flow.

The MCDISK-2 has one PCMCIA slot which enables you to use Compact Flash or Smart Media cards for storage (with the correct PCMCIA adapter). We sell the PCMCIA-to-CF adapters in our Package deals or separately (see Related Products below)."

click here followed by Card Reader Drives for more info. They also have standard CDROM Drives, SCSI Cables, External Hard Drives, Rack Enclosures, and SCSI Hard Drives.

via Giles: "I've just got hold of a SCSI flash drive from http://www.scsiforsamplers.com/ - the "news" part is until recently these flash drives were an unknown/untested alternative to hard drives for many of these old samplers like my Ensoniq EPS16+. This place has done some really good compatibility testing and JD from there provides sterling service. Anyone with a vintage sampler or considering getting one can bring these classics into the the present with these drives, they're a hell of a lot better than ratty old SCSI hard drives"

Korg EX 800

flickr by MetroSonus
(click for more)

click here for mouse over descriptions of the inside.

Bobby on the Minimoog

flickr by K.R. Jackson

full size

"I'm looking into bird-sized, shimmering capes."

kompressor - synthesize

YouTube via Skrabrug. via Mr. Array. Spot the synths.
"youve got to synthesize
KOMPRESSOR :P"

185 Roland 100m analogue sequencer test 1

YouTube via carbontony
"Testing an analogue sequencer by RYK
http://www.flickr.com/photos/ryktnk/s...
Synced by a modded Boss Dr 110.
Tweaking gate switches.
Mastering compression courtesy of Sony Camcorder :_)"

via -ryk:
"In the video the note lengths and pitch have been set by the pots. and switches, and then live tweaking the gate mode and sequence length switches. Drums supplies by modded DR110, that drives the clock input on the sequencer."

M185

The Rife Machine - Healing With Oscillators

This one in via jeswa.

via wikipedia:

"Rife said that he could find a Mortal Oscillatory Rate[17] (M.O.R.) for various pathogenic organisms, and directed his research accordingly, culturing and testing various pathogens with his Universal #3 microscope and his directed radio frequency energy 'beam ray' tube machine. Rife claimed to have documented the precise frequencies[18] which destroyed specific organisms, and claimed that many, if not all, contagious diseases could be cured using this radiation treatment, using frequencies that were typically in the 10 kHz-100 MHz range (HF to mid-VHF).[19] Rife claims that a clinic was set up by a Dr. Milbank Johnson M.D. which conducted tests using Rife's machine on the growth of typhoid in medium, which he claimed demonstrated no motility of typhoid rods which were exposed to Rife's machine.[20][21] There is no independent verification of any of these claims."

Image via http://www.rife.org/rifemachphotos.html
You can find more info on http://www.rife.org/
You can find a software Rife Machine here: http://www.rife.bztronics.com/
And Australia is cracking down: link.

Not directly related, but there is mention of using sound for therapeutic purposes in this Hataken Interview - check it out when you have time - it's an interesting read.

Update via alfried in the comments: "Its good to see your post, thanks for the information. Rife generator is a machine that generates electromagnetic frequencies especially targeted to deactivate harmful toxins on the body."

Homage

"28 minutes of modular noises with a theremin overdub. All improvised and un-edited. The modules in use are two osc., two multiband filters, delay, env, lfo, vca from Analogue Systems. The theremin is an EtherwavePro."

via L. D. Terkelsen www.myspace.com/ldterkelsen

Yamaha TQ5: Apparently, Bill Holland CAN Touch This

YouTube via gearwire. follow-up to this post.
"Now that Bill Holland has got you all MIDI connected and whatnot, it's time to bust out more of the Yamaha TQ5's capabilities. The TQ5 is basically the 1980s crammed into a stealth-looking box. Be sure to put on some neon pants and level your flattop before you watch this video about tone, LFO and envelope controls. See more on gearwire.com."