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The T-500 series was manufactured in the early to mid 1970s. It is the last tonewheel model Hammond ever made. It was a spinet model with two 44-key manuals. It is often considered the least desirable of the tonewheel spinet models, since it is transistorized and has terrible features such as bass rolloff and click filters. However, most of these can be fixed simply by changing about 20 dollars worth of components and removing a few things. The tone generator can also be re-calibrated to give a sound heavier on the bass, and you can certainly add a tube pre-amp between the existing pre-amp and the power amp. This organ, though transistorized, still falls under the "Any Hammond can sound just like a B-3 with a few modifications" category.

The "T" denotes the series, the first digit (5) denotes the model, and the last two digits (00) denote the cabinet style. An "a" or "c" at the end determine whether or not it has the Rhythm III unit, usually board 124-000082 or 125-000082.

For instance, the T-582c would be a T-500 series with a Walnut cabinet and a Rhythm III unit.

The T-500 units came with many different cabinet styles. Most had two internal 12" speakers and an internal Leslie tremolo unit (a speaker and baffle, but no horn rotors.) Often they came with the Rhythm III unit, also referred to as the "drum machine." A tape deck was also an option. Some features included Split Vibrato, preset drawbar and percussion voices, leslie chorus, and typical leslie controls. There were 12 pedals and one pedal drawbar. It weighed in at 130 kg (286 lbs.)

A 9-pin plug on the back for an external Leslie 700 series was also common.


Most T series organs in good condition can go for between $100 and $200 USD in the states, and approximately 3/4s of the equivalent in the U.K.

Service Information

The T-500 series (and possibly other T-series organs; I wouldn't know) has a drum-type vibrato scanner which is different from the earlier type which mounted to the synchronous motor. For problems with this, see HowToRebuildTheDrumVibratoScanner.

The tape deck, if seldom used, can become extremely whiny and noisy and generally undesirable. If you don't need it, simply remove it (bolts are underneath and easy to see; and you can simply clip the wires) and it will make your life easier. Plus, it eliminates the possibility of extra noise, since it's hooked into the power amp and speakers.

The belt between the vibrato scanner and motor can become stiff stop working if the organ is seldom used. If this happens, there is no hope for it. Simply slip it off and put a good quality rubber band in it. Or, if you're resourceful, go to your local power-equipment store with the old belt and ask the friendly clerk for a replacement that's the same size.

Keys making stupid clicking noises and not physically functioning is often due to their cheap plastic brackets breaking from people playing them too hard. You can take the offending key out and remove or tighten the rear screw on the underside of the key, since this is the one that breaks the most. Don't overtighten or you'll crack it and you'll have little plastic pieces jingling every time you press a key.


Carsten Meyer's website,, provides a full guide to modifications that can be performed on the T-series organs.

Here is a short summary of the most common modifications you can perform on the T-Series organ. Most of them can be found on Carsten Meyer's site, or on various Hammond e-mail groups.

Bus Amps, Bass Roll-off and Intermediate Amp Mod: This gives your organ more "click" and "punch." It involves removing some capacitors from the upper and lower Bus Amps and replacing others, and changing/removing a number of components on the recovery board.

Percussion: You can put harmonic percussion on the percussion tabs 1-4. This involves changing some resistors around on the Upper Bus Amplifier.

Recalibrating Tone Generator: While you can do this on any organ, it makes most sense on the T, since the highs are too loud and cheesy, and the lows just aren't really there.

Overdrive - This is part of Kon Zissis's Zener Diode circuit. On the T, you can add a simplified version of this circuitry, and add several Zener Diodes between pin 8 of the Main Amp and ground. This is outlined in his main explanation of this circuit, in the page ?KonsZenerDiodeBasedOverdriveCircuit.

Chopping - You can do this to any organ. I am working on a page specifically for T chops, to help the less electronically-and-mechanically inclined: TSeriesChop

Feel free to add more mods that I forgot.


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