Hammond E-100 Tone-wheel Organ.



In the mid-sixties, the "big" classic console organs B-3, C-3, A-100 had been on the market for a while, and were now joined by a couple of new console organs, the H-100 and the E-100. The smaller of these (none of these instruments are small!!) was the E-100. The feature set was reduced, compared to the classics. There were no programmable keys, and the electronics were different. And as with the L-100 and later the T-series, Hammond tried to suppress the inherent "key click" with a dedicated key click filter.
But even with these reduced features, the E-100 still consists of fundamentally the same parts as an A-100/B-3/C-3. The same tone wheel generator is used and the same "pie" scanner is used for the chorus/vibrato. This organ also sports a nice two octave radial pedal board, and so, for those of us living in a part of the world where people never part with A-100s, B-3s og C-3s without an unreasonably hefty price tag, an E-100 might just be the ticket to a real console with the "big" sound.

Features:


Made on license from Hammond in Denmark by Brdr. Jorgensen. It seems that Brdr. Jorgensen built Hammond organs for all of northern europe in those days.

Judging from the comments I get from US members of the organforum, big Hammonds are not nearly as common here as in the US, and this means that big console organs demand very high prices here. I can see that in the US the big classics go at reasonable prices, while the "sleepers" like E-100 and H-100 are sometimes given away for free. Here, an E-100 will cost something, but only a fraction of a big console. So if you are looking for a bargain console Hammond, these are the ones to look for.

Fixing common issues

For the first 2 and a half years I owned this organ neither the reverb nor the chorus worked. Also, the Leslie adaptor is not compatible with a 760 Leslie, so I had to play it through an MXR 100 tapped from the phones out. Not optimal, and not ideal for the music I play. It was a matter of practicality, as my two organs were in opposite locations of what they ought to be. I finally got them switched, and so I finally got a chance to work on the E-100, and fix all issues.

First issue was the reverb. No sound! I measured the signal path with an oscilloscope, and found that nothing was fed to the reverb tank. The problem was a bad phono plug connection. After unplugging the reverb send a couple of times, the reverb came back. This organ seems to suffer from bad connectors, so phono connectors and valve sockets are the usual suspects when looking for bad connections.
Next issue was the scanner vibrato. With the scope and the schematics at hand, I concluded that signal passed through the scanner, but no phase variation happened. These are the symptoms of a stuck scanner! The problem is, that access to the E-100 pie scanner is very difficult. You can loosen the TWG chassis and slide it to the left, which will give you just enough room to unscrew and take of the covering can at the end of the scanner. But if you need to completely disassemble the scanner then poor you. The procedure requires unsoldering several wires, moving and streatching several other wires and sort of turn the scanner end of the TWG chassis over the back edge of the cabinet.
Fortunately for me I did not have to do this. Removing the end cover was sufficient to be able to turn the scanner manually. It was not entirely stuck. After turning it manually with the organ on for a while, the resistance eventually gave in and the scanner started to spin. I have then tried to put oil onto the oiling threads, so it will oil the scanner bearings. But now the scanner also works again!
I have been extremely pleased with the sound of the E-100 with just these fixes. The chorus is great, and gives that classic B-3 type sound. The stereo reverb is stereo in that it has its own amplifier. Reverb comes from a seperate power valve and speaker. This means that the vanilla E-100, even without Leslie, is a great sounding organ!



Modifications

The E-100 organs can be modified, but not quite as easily as with the T-series organs in my opinion. First of all you have to consider that the organ is essentially a valve-amplified organ, and as such you are dealing with very high voltages around the valves and the power supply. So care must be taken. Second the organ is somewhat more complex than the T-series mechanically. Modifying the percussion presets is not a simple matter of moving a few resistors around on a PCB board - as on the T-series - but requires you to rip out the entire precussion panel and unsolder several wires.

But it can be done. There are some good instructions for modifications to be found on the web. Try to trace down a document called "Beauty in the E", describing many mods. Unfortunately the writer does not want the document to be made directly accessible by links, so I cannot make it accessible. However, the writer does allow copies to be sent personally to other mod'ers, so all you have to do is ask!

In any case, http://www.organforum.com/ has several threads dealing with modifications of the E-100 to be found, and some of them are very simple. I have made two of these mods, to great effect. The key click filter may be bypassed entirely. This brings out a more pronounced key click, as well as giving the entire organ more definition. Another great mod I made was to solder a 2K2 resistor from the open tap on the reiteration pot to ground. This turns the reiteration knob into a variable percussion length knob. Very useful to give a more pronounced popping percussion, and it is actually more flexible than the usual long/short decay tabs.

I always equip my organs with an effects loop at an appropriate place, and I have found that the perfect insertion spot for the E-100 is right where the signal leaves the volume pedal and enters the power amp. The signal levels there seem perfect for my beloved Vox Big Ben valve overdrive, and produces a mean Jon Lord style heavy sound.

I also built my own Leslie adaptor, as the organ only has an adaptor for an uncommon Leslie type, incompatible with my 760. The classic Leslie 9-pin plugs are hard to find, but instead I decided to use multi plugs commonly found on computers. There are no high voltages coming from the 760, so this works fine. I installed a Leslie speed switch on the lower front panel. The E-100 has separate amps for main signal and reverb, so in order to mix the two, I installed a 56 ohm resistor from each amp output, and took the Leslie signal from there. This is a way to mix clean and reverb signals. The levels are correct for the Leslie.