Hammond Tone Generator Project - Part 1

Early this year, I acquired a tonewheel generator (TWG) from a Hammond series H organ. The H series was rushed into production to compete with offerings from other organ companies, and suffered reliability problems as a result. Here are some photos :

The Tonewheel Chronicles

This TWG had already been removed from the organ and was headed for the dumpster when I picked it up. I have bolted it to a wooden frame to prevent flexing. The Hammond tonewheels organs were produced from 1935 until 1975. Tones were generated by spinning a toothed steel wheel next to an electromagnet. The wheels rotated at a fixed rate, locked to the speed of the synchronous motor. When operating properly, the TWG never went out of tune. This was an improvement over electronic oscillators, where at least 12 oscillators must be tuned to their appropriate pitches. Here is a more extensive description : http://en.wikipedia.org/wiki/Tonewheel So, what can you do with a TWG from a Hammond organ? First, I needed to test the TWG to make sure that it was operating properly.

Synthesis on the Parallax Propeller

Have been experimenting with audio synthesis on the Parallax Propeller chip. The Propeller is a 8 core multiprocessor chip that can be purchased for $7. It is remarkably capable...the processors share the I/O bus on a time slice basis, so each processor knows when it has access to the I/O bus. Anyway... There is discussion on the forums about a SID Synth project. It runs an emulation of the Commodore 64 SID chip in 4 of the 8 cogs (processors). The processor accepts MIDI input and passes the note commands to the various cogs. Here is a link to the forum discussion : http://forums.parallax.com/showthread.php?133075-Polyphonic-SIDcog-synth-WIP Even more interesting, the circuit is capable of digital audio output via a simple RCA connector, using the S/PDIF protocol. I am using it with a $20 S/PDIF to Analog audio converter. I have the digital audio working, unfortunately not yet with the SID emulation. WIll be working on this. While this is nothing like having real SID chips, it is pretty impressive for what it can do.

Microsoft Family Security. Useful? Not Really.

I'm trying out Microsoft Family Security on our Windows 7 box. Following is the list of software that my son is "using". Completely accurate, but pretty useless. There are 3 real programs in here : Google Chrome, Nero and Snagit Most of this stuff runs in the background all the time. Apparently there is no way to exclude this background nonsense from the report. I don't want to disallow it, because then everything breaks :

Citrix online plug-in Connection Center 4 hours 8 minutes

Event Monitor User Notification Tool 4 hours 8 minutes

Google Chrome 4 hours 8 minutes

HP QuickPlay Resident Program 4 hours 8 minutes

HPWAMain Module 4 hours 8 minutes

hpwuSchd Application 4 hours 8 minutes

Internet Low-Mic Utility Tool 4 hours 8 minutes

Politics : Don't like the facts? Legislate them away

Our legislature in action : Climate change may be illegal So, if you don't like the science, make it illegal. This is the legislative equivalent of putting your fingers in your ears and saying "La La La, I can't hear you.

Project : Clavinova - where to go from here?

My attempt at repairing the Clavinova CVP-87A did not help (the audio output still sounds terrible), but there was a silver lining. It turns out that the MIDI out still works. I am currently using a Yamaha external MIDI sound module as the sound source. I disconnected the audio output of the mainboard, and connected the audio output of the MIDI module to the external input of the Clavinova. Unfortunately, there is no volume control of the external input -- the volume controls on the Clavinova do not work.

So, it is a perfectly good learning piano. I take my piano lessons on it. I love the way it plays. However, I can only control program changes. The first 10 are on their own buttons, the other 50 are available through more keystrokes. None of the other controls work, including the floppy disk interface. Every key has a corresponding LED, which is used to indicate the position of keyboard splits, among other things.

So my options are :

• Purchase a new mainboard for about $500, which leaves me with a Clavinova and its' 1993 era voicings. Next year it will be 20 years old.
• Do nothing and continue to use it as a piano controller with a bunch of non-functional controls. This is practical, but somehow dissapointing.
• Replace the electronics with something more modern. I have looked at commercially available MIDI controllers. Almost none of them provide for velocity sensing and very few provide for control of 88 keys.

I have thought of building a computer inside the Clavinova. There is plenty of space. I could probably salvage the amplifier boards, but not much else.

Logitech Orbit AF - Only in Ubuntu :-)

Grabbed an old Logitech Orbit AF cam to do some video conferencing. Logitech does not support this device under Windows 7, and Mac OS X does not recognize it. Finally tried Ubuntu 11.10 and the camera WORKS, though the audio does not. Amusing.

It's been awhile : new HP laptop series naming?

It's been a while since I posted. HP has just come out with a new line of laptops -- The HP Spectre. Looked up the definition of spectre on the Free Dictionary : spectre US, specter [ˈspɛktə] n 1. (Spirituality, New Age, Astrology & Self-help / Alternative Belief Systems) a ghost; phantom; apparition 2. a mental image of something unpleasant or menacing the spectre of redundancy Hmmm.

Success : Auto update of Ubuntu 11.04 to 11.10

Did the "click the button" update from Ubuntu 11.04 to 11.10. Zero problems. I did have to ask Mr. Google how to get the old Gnome desktop back. This is the 2nd time I have done a hands off (mostly) Ubuntu upgrade...previously from 10.10 to 11.04. That upgrade was also flawless, but I did have to answer a few questions about keeping files that were to be replaced. I have been using Ubuntu as my primary desktop for the last 3 months, and have been very impressed. The biggest problem with using Ubuntu at NCSU is the problem with configuring the VPN. Which is totally a Cisco problem....their client assumes that Firefox is installed and tries to save the certificate in a .firefox directory. If that directory does not exist, the VPN client fails with a generic message. Why this dependency even exists is puzzling.

Roland - Why such cheap connectors on expensive gear?

I just finished repairing the 2nd piece of Roland music gear in the past two months. Earlier, I removed the audio output jacks from a Roland SPD-S Sampling Pad and replaced them with a cable to an external breakout box. The 1/4 in output jacks are used more than any other connector on the device, but the parts are of poor quality, and mounted in such a way that guarantees their failure. No strain relief is provided -- all the stress of plugging and unplugging audio connectors is absorbed by the connector and its' solder joints. While the connectors are threaded for a mounting nut, the design does not allow them to be added. Original retail on this device was between $500 and $800. Earlier this week, I repaired a Roland RD-700SX Stage Piano. Original retail was likely between $1000 and $2000. The contacts of the power connector were totally mangled. Rather than use a replacement part that would likely fail again, I used a connector from an old piece of test gear.

Open letter to HP

Guys,

I know you are having a hard time right now (and by the way, my HP stock is way down), but this is not the time to be running from the hardware business. My opinions vary on your consumer products, but my ongoing good experiences with your server class hardware tells me that you should keep doing that. Your background in instrumentation and testing gives you a good perspective on how to develop systems that can be monitored and maintained effectively. Keep it up.

--tom

Hammond T-595

From Hammond T-595

My new, old Hammond T-595. The previous owner got as far as painting the organ to match the room. Has a built in Leslie. From the symptoms (hum, very low sound), I'm guessing bad capacitors or a bad output transistor.

The Hammond T-500's were the last of the tonewheel organs that Hammond produced. Tonewheels generate sound via spinning metal discs and electromagnets. The drawbar controls allow a specific mix of harmonics in the output.

Amusingly, the T-500 Hammond incorporates circuitry to eliminate the uniqueness, classic, Hammond B3 sound. Forutunately, The modifications to reverse these "improvements" are well documented.

Project KOW : Console design

The jOrgan software uses "dispositions" as configurations for how a virtual organ will look and sound. When these dispositions are very complex, the control scheme is also complex. Generally, the player will choose combinations of stops and apply them to "pistons" which are basically presets. These pistons are physical controls and are generally located below the manuals, though pistons can be displayed on the computer screen and selected with the mouse, or via a touch screen.

During the performance, the pistons allow rapid changes of stop combinations that could not be achieved by manually changing the stop tabs. My first "proof of concept" organ used a ELO touchscreen, which allowed me to tap the screen to make changes.

So, now to console design. A touchscreen allows access to many stop tabs and pistons, but lacks the tactile feel of real switches. One can glance at physical switches to check and change configurations, but this is much more difficult with touchscreens.

I did extensive research online to help me decide on a design for my console. I have narrowed this down to Schlicker and Holtkamp consoles, as they often used a very minimalist design (some call it ugly) The console that most approximates what I am planning is this Schlicker practice organ :

http://mysite.verizon.net/dalderdi/organ/

Reducing the number of controls allows all controls to be "real" and eliminates the need for a computer display. This will allow me to concentrate more on playing, and less time fiddling. There will be likely fewer than 30 physical control elements, which also makes the console project much more "doable". The thought of wiring even 100 different controls is daunting.

Hardman Wurlitzer in Virginia

The theatre organ that Cameron Carpenter uses on his "Cameron Live!" DVD/CD is located in Great Falls, Virginia near Washington, DC :

http://theatreorgans.com/wurlitzer/

The reconstruction story is very detailed.

An entire building was built for the organ console and pipes. My understanding is that the local zoning board would not allow the owner to build a new structure that was bigger than his house, so the organ "barn" was built as an addition (connected by an enclosed corridor) to his existing house.

Project KOW : The portable organ project

For my current musical project I thought it would be fun to bring a virtual pipe organ to the recent North Carolina Maker Faire, but a traditional organ console was not very practical. I would need something more portable. Portability was necessary for my situation. But what if portability were a design goal rather than an inconvenience?

This requires a rethinking of the organ console, which has remained relatively unchanged for hundreds of years. Since I have only recently started piano lessons, I have no preconceptions of how an organ console should work.

The computer side is relatively easy if your goals are modest.

BUILDING AN ORGAN
The organ that I displayed at MakerFaire was rather minimal -- a touchscreen, a laptop and a 61 note MIDI keyboard. I ran the jOrgan software under Windows XP.

GOALS
My goals for the console design are :
AGO standard manual (keyboard) spacing - An organist can play it
Self-contained - No separate computer
Reduced size and weight - I can carry it
Appliance philosophy - The computer is there, but hidden
Don't reinvent the wheel - Use commercially available parts when practical
Flexibility - Be able to experiment with different interfaces without having to start the project over
Modularity - Be able to expand without having to start over

Next : Design

KOW (Karches Organ Works) at MakerFaire NC

The response to my VPO project at MakerFaire was tremendous. Thanks to everyone that came out. I will be adding more information shortly.

Building a VPO console

For those of you that saw my VPO setup at MakerFaire North Carolina, I have added some links in the sidebar to VPO related sites and resources.

VPO software
If you want to try out VPO software without having to install software to your hard drive, I would try the jOrganPup distribution which boots from a USB key and runs on most PC hardware. It runs very well on older hardware.

The MidiTizer software is an emulation of a theater pipe organ. It is more complex than jOrgan Pup and is intended to run under Microsoft Windows. There is a version that runs in the WINE Windows emulator under Puppy Linux.

The Hauptwerk software is a commercial product that run on Mac OSX or Windows. There is substantial documentation on line. It will run in a limited "free mode" or with a license key. The free and purchased versions are the same...the USB license key activates the additional functionality.

VPO Hardware
M-Audio Keystation 61es - this is a semi-weighted keyboard which is often used in DIY organ consoles. I have been buying my 61es keyboards from Unique Squared, an eBay vendor that sells B-Stock keyboards that have minor blemishes (usually on the case and are fully guaranteed) for $124. Since I am removing them from the case, the blemishes are usually irrelevant. Brand new are about $170, so this saves about $50/keyboard. I have ordered 2 and they are both fine.

MakerFaire tomorrow : KOW Opus 1.0 and Flag-O-Matic

Just about ready for MakerFaire tomorrow. Will have my VPO project (KOW Opus 1.0) and Dad's Flag-O-Matic prototype on display.

MacBook Pro : Post Mortem

I was recently given a 17 inch MacBook Pro by an acquaintance. A very DEAD MacBook Pro. His son had spilled a drink into the keyboard. Its' demise soon followed. I had the opportunity to tear it down completely, looking for usable parts.

If you own a unibody MacBook Pro, the most extensive repair I can imagine would be to replace the keyboard. Everything must be removed from the unibody to access the keyboard, which is held down by about 20 very small screws. There is an interesting variety of cable latches (standardization, anyone?) that must be undone. Some cables are connected via a friction fit.

So, if you own one of these Macbooks, and insist on keeping a drink close by, I suggest you invest in a good quality no-spill cup and use it (I personally like the Contigo, available at Target). The Contigo remains sealed unless the flow button is pressed.

If you do have a spill and mess up the keyboard, I would buy an external Bluetooth keyboard before I would do a keyboard replacement repair.

Project : Low cost organ (VPO) console

I've been on a pipe organ kick lately, more specifically Virtual Pipe Organs (VPO) and I'm thinking of building an inexpensive organ console for the upcoming Maker Faire to show what a VPO can do, and encourage people to build their own.

I've decided to combine inexpensive piano keyboards, a pedal board and preset switches --- materials I already have, and do it as simply as possible. I will be gutting the sound generating parts of the keyboards and using a Highly Liquid MIDI CPU to do the required interfacing. If one already has the keyboards, this project can easily cost less than $100. The MIDI CPU is only $44.

To work within the limitations of one MIDI CPU, I've decided to use 49 note keyboards. 61 note keyboards are the norm for organs, but they are much harder to find cheap or free. Using 49 note keyboards should allow me to interface everything with one MIDI CPU.

More details as I work them out.

Here is the Picasa album : https://picasaweb.google.com/tkarches/LowCostVPO

Dumb story on LED bulbs

Another crap study finds :

LED bulbs not as eco-friendly as some might think

Considering that :

- These lights will probably be burning after I am dead
(there is one in my ceiling fan)

- I don't plan to put them anywhere but a light bulb socket

Also, since LEDs last longer, there will be fewer in the landfill.

I'm not the least bit concerned. If the bulb burns out, I don't plan to pulverize it as they did in the story. What a worthless piece of journalism.

And quoting from the (stupid) story :

Incandescent bulbs, incidentally, contain very high levels of lead and mercury, while compact fluorescents are also high in mercury.

So what do they propose? We replace all our light bulbs with candles? Wait...lets do another study first...