My project... since others are posting

[Bob-I]

Kinda odd projects for a guitar player with little to no keyboard skills, but here they are...

First I found a 1971 Hammond Porta B on Craigslist for $100, not working. For non-Hammond folks... Hammond developed the first, and BEST electronic organ. It's based on toothed wheels spinning at 60Hz and magnetic pickups. Each of 82 wheels produces a sine wave like tone. 9 of these tones keyed by each note and are mixed with the drawbars.

From the drawbars the sound goes a preamp, in the Porta B there are 2, one to increase the amplitude of the signal and add vibrato, the second to produce a percussion tone. From the preamps it goes to a small 12 watt 2xEL84 power amp.

There are 2 manuals with 44 keys each, pedals with 13 keys. In this Porta B someone added a "string bass" board which modded the pedal tones, added sustain and an octave divider plus a separate out and volume knob. Count the wires, 9 to each of 44 keys/manual, 81 from the tone generator, the list goes on... there are thousands.

It had a ton of problems from being dragged out on the road. Power amp had blown some power resistors due to shorted can caps. Many of the connections from the bottom unit where the pedals and power amp are located were screwed up. I basically stripped out the wiring and started from scratch.

About when I got the Porta B running (about a $50 investment and many hours) a friend saw an add on Craigslist for a C2 from the 50's. C2 is similar to a B3 but in a "Church" cabinet and no percussion.

When he got to the house, it turned out to actually be an A100, the home version of the B3. All the same mechanics and electronics in a decorator cabinet, with the addition of 2 power amps, each 12 watts, one driving 2x12s and one driving reverb into 1x12.

I picked up the A100 for $100, sold the Porta B for $250 and went to work. The A100 has 2 manuals with 61 keys and 12 presets, 25 bass pedals with 2 drawbars. The vibrato is mechanical, runs on a scanner/delay system with an RC filter bank. The tonewheel Generator is 92 tones, which explains the fat B3 tone and additional weight.

The tonewheels were squeaky due to lack of oil, added Hammond oil and let it wick in. Powered right up but some functions were less than perfect.

The A100 has presets in addition to drawbars. The presets are an octave of reversed color keys with a latch, C-A are set tones, Bb and C activate the 2 sets of drawbars. The latch didn't work. Reverb had a terrible hum, bass pedals were a crapshoot, some worked, sone stayed on all the time, some wouldn't make a sound.

Repaired the preset latches, just gunky lube, adjusted the pedal springs, cleaned all the tube sockets and drawbars. Now everything is functional without a single part swap but the reverb is thin sounding. I swapped with a known good tank, perfect. The old tank has a spring disconnected, maybe I can fix it.

Now read again... not a single part replaced. Original tubes, some with datecode 1957, all 18 tubes have Hammond labels. Not a single key fails to play all 9 overtones, vibrato scanner is perfect.

Part 2 of the project, building a Leslie. I located a bottom rotor/motor/speaker assembly which I'll pick up next weekend.

Any interest in the tonewheels check this http://www.youtube.com/watch?v=7Qqmr6IiFLE

[Buschman]

Wow Bob, labor of love no doubt. Most of us would have gutted the poor thing and built a cool head cabinet from the mahogany. I have a tone cabinet I pulled out of a dumpster if I can get it back from my friend. Beautiful wood and about ten alnico speakers in it. Needs work but would love to hear that with the leslie cranked up doing some vintage Stevie Winwood.

[M Fowler]

Great project and wow lots of work.

I rewired part of an old Lowery organ once and never again.

Now if farmer Jerry down the road wants to get rid of his two Hammond B3s I will bit on those.

Mark

[ampmike]

Wait till you try a leslie,amazing sound.You got a real cool find,Good Luck,Mikey

[passfan]

Looks like an HO-43 chassis. You probably got some Blackburn Mullards in there if you're lucky. Any tube labled "Great Britain", visible seam lines on top, and a B*** code etched or sometimes printed on the side of the tube. The el84's are probably from Holland and could be Amperex. Hammond routinely relabled these and they sound great in guitar amps like the Express , and the Liverpool. I haven't had any success with them in the Rocket though as it's a bit cleaner.

[Bob-I]

Bushman: Gutting this work of art would've been sacrilege although many folks do. I'll guess that if I gutted it I could make $2k on selling the parts.

M Fowler: Lowery's don't count no tonewheels.

passfan: I thought the HO-43 was a tone cabinet power amp. This organ has an AO-28 preamp, AO-35 Reverb amp and AO-39 power amp. I haven't looked at the tubes in detail, but they will stay in the organ in the case that I might eventually sell this organ as 100% original.

[martin manning]

Why is the guy in the video jaming the pickups into the tone wheels? And, something I've wondered about before, what exactly do the stops do to the mechanism?

I've always loved the B3 sound. There is a cool piece on NPR's site, an interview with Booker T Jones. He talks about his early days of taking piano and then organ lessons, and plays Green Onions. Priceless!

[David Root]

Always loved the B3 tone. I didn't know there was a home version. My wife would kill me if I bought one, especially as I'd have to take lessons to learn how to play it.

[martin manning]

M Fowler: Lowery's don't count no tonewheels.

Tell Garth Hudson...

[Bob-I]

Why is the guy in the video jaming the pickups into the tone wheels? And, something I've wondered about before, what exactly do the stops do to the mechanism?

He's demonstrating just how over engineered Hammonds are. In fact the first Hammond built in 1935 is still operational.

The drawbars adjust the level of the harmonics, in organ terms, stops. Each key can play 9 harmonics. There's drawbars for the fundamental, 5th, 4th, octave, sub octave etc. Each organ tone is a combination of these overtones. Hammond called it "additive synthesis"

I've always loved the B3 sound. There is a cool piece on NPR's site, an interview with Booker T Jones. He talks about his early days of taking piano and then organ lessons, and plays Green Onions. Priceless!

The organ in the studio was not a B3, all of the early Booker T recordings were done on an M100 with the exception of "when a man loves a woman" which he played on a farfisa.

Even many of the classic Hammond recordings like "gimme some lovin" and "whiter shade of pale" were done on an M series. The B simply cost too much money.

I've seen that vid of Booker T, great stuff. He's so laid back but also amazingly talented.

[Bob-I]

M Fowler: Lowery's don't count no tonewheels.

Tell Garth Hudson...

I meant the rebuilding part. I've seen the big lowerys too, amazing machines, but hammond IMHO is heads and tails above anything else.

Garth did some great work on that huge theatre organ, steppenwolf also used a lowery and got great tones but they used a Hammond when they could afford it.

[martin manning]

The drawbars adjust the level of the harmonics, in organ terms, stops. Each key can play 9 harmonics. There's drawbars for the fundamental, 5th, 4th, octave, sub octave etc. Each organ tone is a combination of these overtones. Hammond called it "additive synthesis"

Thanks for the explanations. I should look this up, but I was wondering how the drawbars add a harmonic... by electrically connecting an additional pickup? And, does nine tones per key mean that each key activates up to nine pickup circuits depending upon the drawbar settings?

[passfan]

passfan: I thought the HO-43 was a tone cabinet power amp. This organ has an AO-28 preamp, AO-35 Reverb amp and AO-39 power amp. I haven't looked at the tubes in detail, but they will stay in the organ in the case that I might eventually sell this organ as 100% original.

I just got one off ebay that came out of an L100. Also included the vibrato and percussion amps as well. It's a spitting image , tubes, caps all in the same place.

[Bob-I]

passfan: I thought the HO-43 was a tone cabinet power amp. This organ has an AO-28 preamp, AO-35 Reverb amp and AO-39 power amp. I haven't looked at the tubes in detail, but they will stay in the organ in the case that I might eventually sell this organ as 100% original.

I just got one off ebay that came out of an L100. Also included the vibrato and percussion amps as well. It's a spitting image , tubes, caps all in the same place.

I had an L100 (PortaB, same organ). This is completely different components.

[Bob-I]

The drawbars adjust the level of the harmonics, in organ terms, stops. Each key can play 9 harmonics. There's drawbars for the fundamental, 5th, 4th, octave, sub octave etc. Each organ tone is a combination of these overtones. Hammond called it "additive synthesis"

Thanks for the explanations. I should look this up, but I was wondering how the drawbars add a harmonic... by electrically connecting an additional pickup? And, does nine tones per key mean that each key activates up to nine pickup circuits depending upon the drawbar settings?

Exactly. Each key has 9 contacts under it which are wired to pickups in the tonewheel generator. From the keys the signal goes to the drawbars and depending on settings, the harmonics are send to the output.