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Headphone Mixer/Amplifier Installation Kit Rev.6

NEW! On-board muting. Easier to install.

(Mix down 6-channels to 2-channel stereo headphone channels)

Works on any organ with RCA plugs and jacks

This Headphone Mixer/Amplifier Installation Kit (Photos #1 and 2) was designed specifically for the Allen Organ MDS-317, 4-channel Theater Organ but it can be used in other installations where a headphone is desired.

This kit is no ordinary "Headphone Mixer". Besides being a headphone amplifier and 6-channel (optional 12-channel) mixer, the unit performs two very important MUTING functions;

1- When the earphone plug is inserted, the circuit MUTES the audio going to the amplifiers. This prevents any organ sounds from going to the speakers. The organ plays only through the headphones.

2-It MUTES the organ startup sounds (pops, crackles, ARTE sounds that may start, etc.) so that these noises do not enter the headphones.

Since electronic organs usually have several channels, it is necessary to combine those channels (called “mixing down”) into two channels, one for the left earphone and one for the right.

This kit can mix up to six channels. An additional "Piggyback" board can be ordered which will add 6 more channels. Each audio channel in the organ is input to the Headphone Mixer/Amplifier ( abbreviated HMA from now on) printed circuit board.

The HMA picks off the audio from each channel connected and uses this audio, after mixing and amplification, for the headphones.

Since the inputs to the HMA are buffered, the addition of this kit will have no effect on the normal operation of the organ.

The Headphone Mixer/Amplifier installation kit will allow you to hear your organ without disturbing anyone. When you plug in your headphones you will disable the organ’s amplifier and speaker system. This will allow you to hear the organ through your headphones.

All necessary items are included in the installation kit. No soldering is necessary. All you need are some basic tools and basic skills. You should not have any trouble installing this kit. Estimated time to install is from 1 to 2 hours depending on installer skills.

Tools required: awl, phillips screwdriver, flat blade screwdriver, 3/32” & 7/64” diameter drill bits and drill, needle nose pliers, wire stripping tool, wire cutters.

Just installing headphones to an organ output would not give the results desired.

The Cinnamon Hill Headphone Mixer/Amplifier printed circuit board performs several functions that are necessary for a complete operation. These are:

  1. Making the Headphone Mixer/Amplifier transparent to the operation of the organ. Each input to the HMA from each organ channel is buffered (isolated and amplified) so that there is almost no load placed upon the Allen Organ mixer output.
  2. Having each input contain an associated un-mixed RCA jack output for connection to the organ’s amplifier input. This allows for normal operation of the organ using the speakers.
  3. Having the volume of each channel of the HMA mixing circuit individually adjustable.
  4. Having individual volume controls for the mixed left and right earphones.
  5. Incorporating the MUTE function of the Allen organ so that the Allen Organ amplifiers are switched off whenever a headphone is plugged into the jack.
  6. Having the headphone amplifier muted upon start-up for a few seconds so that the various clicks, pops, and other annoying sounds from the computer do not enter the user’s ears.
  7. Having the ability to expand to 12 (or more) channels.
  8. Having a basically flat frequency response from 40 Hz to over 20,000 hertz.
  9. Having the organ easily returned to its original wiring if necessary. ***No permanent changes have been made to the Allen Organ***


Technical specifications:

Power Supply: 12v at 100 ma minimum (supplied).

Minimum input voltage, P-P, for an output to headphones: 20 mv.












The Headphone Jack and Box mounted on the right side of the console. It can be mounted on the left side if desired.

When the headphones are plugged in, the organ's speaker amplifiers are disabled so that the audio will only be heard in the earphones.











Completed Installation of the

Headphone Mixer/Amplifier Kit

The HMA board is located just below and to the right of the green Allen Organ Audio Mixer board.

All audio connections are performed by RCA plugs and jacks.

The black wire on the bottom left of the HMA board is the power cable coming from the "Wall Wart".

The white wire to the right of the black cable is connected to the MUTE function on the Allen Organ amplifier. A terminal strip (included in kit) is used to place this cable in series with the MUTE function.

The thicker silver cable on the right goes to the headphone box.

Detailed instructions are in the pdf file below.




Conceptual drawing of how the HMA is connected

More detailed information can be found in the HMA Installation Manual




Instructions for installing the HMA kit are provided below in the PDF file.

Click here to see the User Manual for the Cinnamon Hill Headphone Mixer/Amplifier Installation Kit R6. (PDF file 1.21 MB).

We reserve the right to change layout and/or component values in order to improve the HMA operation if necessary.




Pricing for the HMA-1 Headphone Mixing/Amplifier board installation kit R6:

$250 shipping included

Go to ordering page


You can contact Andy at: italiano34@hotmail.com email address.

or you may email to: italiano34@hotmail.com

Or you may call: 828 524 9511 (Otto, North Carolina)

Please call first to check stock and production before using PayPal.


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