Conn speaker pipes were a product of the Conn Organ division of C.G. Conn, Ltd. and first appeared in the 1960's during the heyday of the electronic home organ.
These were rectangular wooden chests supporting factory tuned aluminum pipes constructed with either two or four 6 X 9 inch oval speakers in the pipe chest which were mounted end-to-end and fired up through the bottom of the pipes (photo).
The sound from the speakers, which were all wired the same, excited the column of air in the pipes which were designed to sympathetically resonate at certain frequencies.
The idea was to enhance and enrich the harmonic structure of the sound, particularly the higher-pitched reeds, strings, mutations, and mixtures in much the same way as lifting the dampers from all the strings of an acoustic piano.
Conn engineers had a demonstration of this where a small microphone could be dropped inside any given pipe.
This microphone was hooked to a regular guitar amp.
They also had a set of 145 pipes labeled as to their tuned pitch.
While holding down middle "C" on the organ, the microphone would be lowered into ANY "C" pipe, and a "C" was heard coming from the guitar amp.
Then, while still holding the middle "C", the microphone would be lowered into an "E" pipe, and one would hear an "E" coming from the amp, and likewise with a "G" pipe, a "G" would be heard coming from the amp.
In addition, the sound became non-directional.
There was also a very slight bit of sustain, or reverb, to the sound after the key was released as the sound within the pipes dissipated.
These units worked the same way with ANY brand electronic organ whether it was vacuum tube oscillator, transistor oscillator, or analog; today, it's also possible to have them play throuth a digital or a virtual pipe organ (VPO).
These units work best on frequencies from 200 Hz (tenor G) on up and are not good for reproducing the 8-foot bass octave or any 16-foot pedal tones -- a large powered subwoofer would still be needed for that.
Also, while they're made to resonate at different frequencies, the pipes themselves are not tunable.
The Conn organ division manufactured a large line of products, these units were just one of many, a ton of them were sold back in the 1960's and 70's, and those individuals who happen to have them connected to their own electronic instrument today seem to be quite satisfied with them, for their intended purpose.
These chests may stand vertically or be placed on a shelf horizontally, like real en chamade pipes, with the weight of the chests making them stable enough not to require supporting bracing.
These units went out of production in the early 1970's, and pricing of them these days seems to be all over the place; a lot depends upon condition, as it seems they're easily damaged and not very amenable to shipping given their shape and spindliness.
Whether one likes them is, of course, a matter of personal taste, but many people appreciate having them, and not just for their effect on the sound, but for the "look."