May. 12, 2016

Conn Speaker Pipes

Conn speaker pipes, first developed and patented around 1959 by Conn Keyboards -- the piano and organ division of C.G. Conn Ltd. -- and marketed all through the next two decades were just one of a number of attempts to improve the early analog electronic organ by spreading and diffusing the sound for increased realism.  Other solutions included Donald Leslie's two-speed (fast/slow) rotating "Leslie" speaker first created for the Hammond organ, the Allen Company's rotating variable speed Gyrophonic projector speakers, and the Compton Company's one-speed (slow) Rotofon speaker system used with its Electrone organs.  All of these inventions worked, but in different ways, to enlarge, disperse, and improve organ sound generated electronically back in the day.

Kimball International acquired Conn Keyboards in 1980 at a time when electronic organ sales for the home were in a downward swing, a business move which, in the end, turned out to be non-profitable.  These units from an era long since past, a very rare find these days, were nonetheless well-received technology and a rather hot item for Conn piano/organ dealers during the 1960's to keep in stock.  They were almost always on back order with no unsold display models even in the stores.  Many thousands of these sets were manufactured during those years and shipped all across North America and the English speaking world.  And, thanks to that, enough of them still survive in original working condition for determined and patient enthusiasts to systematically hunt down over time, clean and repair them where needed, and treasure thereafter.
This invention was formed of a vertical array of cylindrical anodized aluminum tubes of differing lengths and scaled diameters finished in either silver or gold and permanently tuned to resonate with various fundamental frequencies of the musical scale, like the bars of a marimba.  These were mounted vertically in single or double rows on a wooden baffle sitting atop a rectangular chest made of walnut wood inside of which either one or two pair of 6" X 9" midrange oval speakers were lined up end-to-end.  Each elliptical-shaped speaker was positioned under a plurality of pipes, screwed tightly to the underside of the baffle, and projected sound waves upward against it; the baffle in turn cushioned the sound as individual frequencies from held notes found their own pipes and caused them to sympathetically resonate.
NOTE: These units were wired in series parallel, meaning that the 6" X 9" oval speakers of each unit were mounted end to end and, when 4 speakers were used [models 145 and 146], were divided into pairs, each pair of which was wired in series and then both pair wired in parallel with each other.  Wiring each pair in series has the (-) side of speaker A connected to the (+) side of speaker B, and the same thing with speakers C and D, respectively.  These two pair were then wired in parallel by connecting the (+) side of speaker A to the (+) side of speaker C, and the (-) side of speaker B to the (-) side of speaker D.  Series parallel wiring is how the Conn engineers maintained a consistent 8 Ohm load on the amp using multiple speakers.

These units have no woofers, no tweeters, no crossovers, no additional circuitry.  With the speakers acting as motors to generate resonance, individual frequencies emitted by the speakers found their own pipes.  All of the frequency selection was done by the pipes.  The sound escaping vertically from the top of each pipe created a three-dimensional sourcing, the enhancement of overtones (upper partial tones) added a finespun but definitely discernable brightening of color of individual voices, and a very rapid but measurable delay in the buildup and decay of sounds tending to soften their attack and release also was noted by Conn engineers.
These were STRICTLY TREBLE AND UPPER MIDRANGE units and, in the case of the Conn organ, meant for connection only with the pulse channel manual voices (diapason, strings, reeds), NOT the Tibias, Vox Humana, or Pedal voices.
CAUTION NO. 1:  No Pedal channel output signal from any electronic organ should EVER be connected to these Conn pipes.  They need to be shielded from all low end signal arriving from manual channels, either by a) setting the amp's bass control at minimum level, b) looping the mixed manual signal through an equalizer and fully damping as much as possible all output frequencies below around 200Hz, or, most easily and preferably, by c) connecting a powered subwoofer between the signal source and speaker pipes and using its crossover to filter the signal arriving at the pipes of unwanted bass, preferably by turning its control knob, if present, to its highest setting

Conn speaker pipes came in 3 models and 7 different types or styles:

1. Model 144 "mini-pipes", type 2, Right elevation [determined by tallest pipe in back row], one pair of 6" X 9" oval 8 Ohm speakers wired in series, 16 Ohm load, 28 pipes in 2 rows of 14 each.
Model 144, type 3, same, with Left elevation [determined by tallest pipe in back row].
DImensions: 21.5" Wide, 8.25" Deep, 29-7/8" High, Wt. 17.5 lbs.

2. Model 145, type 1, Center elevation, two pair of 6" X 9" oval 8 Ohm speakers wired in series parallel, 8 Ohm load, 49 pipes in 2 rows, 28 front, 21 behind.
Model 145, type 2, same but with 48 pipes in 2 rows, with Right elevation.
Model 145, type 3, same with 48 pipes in 2 rows, with Left elevation.
Diimensions: 42.5" Wide, 8.25" Deep, 34" High, Wt. 18 lbs.

3. Model 146, type 2 , Right elevation, two pair of 6" X 9" oval 8 Ohm speakers wired in series parallel, 8 Ohm load, 12 pipes in single row.
Model 146, type 3, same, with Left elevation.
Dimensions: 42.5" Wide, 8.25" Deep, 63.5" High, Wt. 40 lbs.

The 6" X 9" oval Cletron speakers Conn used in these units each had an impedance, or resistance, of 8 Ohms each.  As stated, the 4 speakers inside the 145s and 146s were wired in series parallel with a combined load of 8 Ohms.  The 144s with only 2 speakers inside were wired in series for a combined load of 16 Ohms.  This is important because the output jacks of certain external mixer amps which may be used to drive them may specify 8 Ohms.
The pipes themselves were tuned in equal temperament to sympathetically resonate from 200Hz on up.  With an 8-foot manual stop drawn the tenor G key vibrates at a frequency of about 195Hz, and the tenor G# at about 208Hz, the latter note therefore being the practical downward limit of the 146s.  At normal manual 8-foot pitch the 146s were tuned to resonate at fundamental frequencies of the lowest 12 chromatic semitones from the tenor G# key up to and including the middle G key, with the 145s covering all manual notes above that.  The combinational use of these two models therefore resulted in a continuous spectrum of resonances from tenor G# all the way to the top of the manual compass, naturally weaker in intensity as pitch rises in accordance with the natural laws of musical sounds.  In this sense the model 144 "mini-pipes" offer no real advantage over the 145s save for not taking up quite as much space.
NOTE: in a single rank of 8-foot manual organ pipes a preponderance of tone is typically noted in the bass and tenor registers, resulting in a weakness in the treble that organ builders are tasked to overcome.  The fact that grave sounds also travel farther and have more fullness than acute ones adds to this weakness, especially when the instrument speaks into a large building and is heard a considerable distance from its situation.  Builders counteract this weakness by using increased wind pressures and skillful voicing and regulating in the treble octaves, and, in some cases, with the introduction of properly balanced upperwork, meaning octave (4-foot) and higher sounding harmonic-corroborating stops.  Conn speaker pipes function in a similar manner with electronic organs to augment the intensity of the overtones, or harmonic upper partial tones, of fundamental frequencies generated in the lower ranges of the manuals.
Both types (right and left elevation) of the 146s were constructed with cosmetic notches about a quarter of the way up the length of each pipe, all on the same side, this merely to enhance the visual perspective by simulating the appearance of the labial mouths of cylindrical open metal organ pipes.
In terms of volume output these units are naturally inefficient compared with the power needed to run them, but volume is not what they were built to do.  The only place from which the sound from the speakers emerge is from the top of the pipes, their frequency range is limited, and by turning up treble and volume controls of the other amps in use the effects produced by the pipes can be, and often are, essentially lost.  If only one set of pipes is connected however, the console's own internal amp may be all that's needed to run it.

NOTE:  The sonic effects of these speaker pipes are multiplied, of course, the more sets are connected, and the resulting increase in treble brightness, depending upon the size of the room and distance to the listener's ear, may require a corresponding increase in subwoofer volume to achieve a balanced sound.  Some experimentation and fine tuning of volume and EQ controls is involved with this, but well worth the time.

There's something else the Conn engineers observed when the pipes were tuned:  they not only resonate at fundamental primes but also at higher overtones of the harmonic series.  They had a demonstration of this where a small microphone was dropped inside given pipes.  This microphone was connected to a regular guitar amp, and they used a set of model 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 middle "C", the microphone would be lowered into a "G" pipe, and one would hear a "G" [3rd harmonic, or 2nd upper partial tone] coming from the amp, and likewise with an "E" pipe, an "E" [5th harmonic, or 4th upper partial tone] would be heard coming from the amp.  They also discovered a very tiny but measurable bit of reverb vibration within the walls of the pipes after notes were released.  
Additionally, Conn engineers found that when the speakers were energized by held notes from the organ, the column of air in each pipe had to be put in motion before the sound could escape, resulting in the volume building up before the tone blossomed out the top of the pipes in all directions.  With the pipes tuned to overtones of the same fundamental also resonating, the result of all pneumatic action within the walls of the pipes was found to be unique and unreproducable by any other means.  Additionally, when the keys were released, the column of air within the pipes would not come to rest immediately but would permit the tone to linger for a very minute split of a second before dying away completely -- something which can be heard along with all the other sonic effects but not counted.
These pipe units can be connected to play through ANY make or model of analog or digital instrument, and they're built to stand vertically or placed on a shelf horizontally, like real trompette en chamade reed pipes, the weight of the speaker boxes and their frame bracing making them stable enough to make this possible.  Each unit receives a single mono channel of audio and is designed to connect with the amp driving them using standard 16-gauge speaker wire right off the spool.  These bare wire connections are made more secure by stripping the speaker wire at its ends, attaching 1/8" spade connectors using a crimping tool, and tightening the screw terminals under each pipe box to the spade connectors.

CAUTION NO. 2:  The walnut speaker box is fairly sturdy but not waterproof or indestructible.  NEVER expose these units to water, excessive dampness, or give them rough treatment.

CAUTION NO. 3:  NEVER EVER, REPEAT NEVER ATTEMPT TO ALTER THESE UNITS FROM FACTORY DESIGN, such as by trying to shift wire connections from the bottom of the speaker box to the side, which would involve cutting wires loose from the screw terminals, drilling a new hole somewhere in the side, rerouting the internal parallel speaker wiring to the outside through that hole, and then resoldering and/or making a wire splice to reestablish connections ... all guaranteed to create a potential weak link in the incoming signal stream and render the external wiring more difficult to protect and hide, not to mention destroying the unit's esthetic appearance and resale value.

ONE MORE THING:  On all models and types of Conn pipes the pair of screw terminals where the speaker wires connect are UNDERNEATH the box out of sight and project about 1/8 inch below the bottom surface.  To protect from damage and to keep the unit stable when it sits on a wood floor or other hard surface the bottom four corners of each box are supplied with a rubber foot 1/4 inch tall set about 8 inches in from each end.  If the box happens to sit upon a carpeted suface the entire weight of the unit gets compressed on these four small feel causing the unit to sink completely into the carpet with its bottom, screw terminals and all, missing any free way space.  If the unit is to be moved it should be picked straight up bodily and set straight down.  NEVER EVER, REPEAT NEVER, when moving these units around the room, slide them on a carpeted surface, as this can bend the spade connectors and likely break one or both wire connections.  When it appears that the unit doesn't appear to be working, a loose connection on these bare wire terminals arising from sliding the unit on the carpet is often the cause.  
Conn also made available a special add-on control box to provide easy switching between the console's self-contained speakers and these external pipe units, but these kits are also extinct and even more difficult to locate these days.
Hooking up these pipe units to any analog or digital electronic organ today presents a consideration of critical importance called impedance -- the resistance offered by the circuit to the transmission of an electrical current.
Every amplifier connected to a speaker system is rated for a minimum impedance load (in Ohms).  In Conn organs the simplest way in theory to connect these pipes was to hook them up in parallel with the main pulse channel for the diapasons/strings/reeds and have them powered by the console's internal amplifier.  It's important to understand however that connecting a set of Conn pipes in parallel like this reduces the impedance load to the console's internal amp which is already powering the console's self-contained speaker system and makes it work harder.
NOTE: When 2 resistances (impedances) are connected in series, they total.  For example, a pair of 4 Ohm speakers wired in series results in an 8 Ohm load to the amp (4 + 4 = 8 Ohms).  When 2 resistances are paralleled however, a formula comes into play for calculating the impedance.  The total impedance in parallel is the multiplication of the two loads divided by the sum of the two loads.  For example, a pair of 8 Ohm speakers wired in parallel results in a 4 Ohm load to the amp (8 x 8 = 64, divided by 8 + 8 = 16, which is 64/16 = 4 Ohms).  It's the same result as totalling the loads in reciprocal, whereby 1/8 + 1/8 = 2/8 = 1/4 = 4 Ohms.

Since the minimum impedance rating of most amps is 4 Ohms, it's plain to see that connecting several of these 8 Ohm speaker pipe units in parallel can make the amp work a good bit harder and, if the circuit's impedance is below the amp's minimum Ohm rating, the amp will heat up.  How the speakers are wired therefore makes all the difference in whether or not the amp driving them will continue to operate.
According to Ohm's Law, in an electrical circuit the voltage (V) in watts is the product of the current (I) in amps and the impedance, or resistance (R) in Ohms.  Thus V = IR, and, since the voltage at the wall socket is constant and unchanging, whenever speaker units are wired parallel with a reduction in impedance  the current in the circuit increases.  This, as stated, makes the amp run hotter than it's supposed to.
Original Conn vacuum tube amplifiers, being out of production for many years, are almost impossible to replace these days.  The solid state ones which came later were not quite as particular about impedance as tube amps were, but they were all rated for a minimum 4 Ohm load.  As speakers are daisy-chained in parallel to one another the Ohm load always drops, so, it's never a good idea to try to run a load below that.  Again, with constant voltage arriving from the electrical toggle, low Ohms in the circuit translates into more current, thus, the lower the Ohm load, the hotter the amp will run.  If the equipment has protection circuitry and heat becomes a problem, the amp will shut off at heavy volumes, but the result is still the same:  no sound.     
Over time house dust, pet hair, and even dead insects and other debris falling into the tops of the pipes tends to accumulate on the upward facing speaker cones.  It's advisable in the beginning for these pre-owned units to be taken apart, cleaned and vacuumed, and checked prior to hook-up.  The original pipe finish may be restored using a tube of metallic gold leaf or metallic silver leaf Rub 'n Buff applied with a cotton ball and available from craft retailers.  Unwanted finish that happens to get on the speaker box is easily removed using mineral spirits and paper towels.
The usual choice for replacement of the Cletron speakers, if needed, has been new 6" X 9" oval car audio speakers.  If 8 Ohm replacements are used which are easily available, then the original Conn series-parallel wiring can and should be retained ... BUT ... if replacement speakers rated below 8 Ohms are substituted with no change in wiring the resistance the whole pipe box presents to the amp drops drastically.  For example, if 4 Ohm replacements are used [4 x 4 = 16, divided by 4 + 4 = 8, which is 16/8 = 2 Ohms] it will have the amp operating below its minimum inpedance unless the wiring is also changed.  All that rewiring work can be eliminated simply by using replacements rated at 8 Ohms.

NOTE:  It's most interesting that do-it-yourselfers, building on these discoveries of the Conn engineers, have sometimes constructed their own one-of-a-kind speaker pipe units for their own private use.  Generally these have been built of wood and conventional PVC [polyvinyl chloride] pipe tubing with the idea of extending by an additional octave the compass of the model 146 Conn pipes.  These oversize units can be made in both rectangular and square styles.  The square style involves using a large, sturdy, hollow, square-shaped wooden box inside of which would be mounted a single 12" woofer which projects sound upward through a large, circular opening and through a wire screen baffle to the entire plurality of pipes (usually 12) mounted above it.  Above this baffle would be positioned on-end 12 general purpose [3-1/4 inch diameter] PVC pipes of varying lengths.  In this style the pipes would be bundled tightly together, painted a metallic gold or silver leaf color to match, and cut to proper lengths to resonate sympathetically at frequencies from around 8-foot tenor A down to 8-foot bass A [100Hz] or thereabouts and at higher harmonics of notes below that.  Since these pipes are all of the same diameter their positions over the speaker cone has much to do with their lengths because the air inside them vibrates at different velocities depending upon how much sound each of them receives.  Those clustered over the center of the speaker face receive the most sound while those situated to the outside occlude only the edge of the speaker cone.  This explains how two different pipes of identical diameter in these units which are tuned to resonate at neighboring chromatic semitone pitches could be very close if not equal in length.  It is not unusual for custom built, one-of-a-kind units like this to stand something over 7 feet high and overlap the tuning of the bottom two semitones [tenor A and G#] of the model 146 Conn pipes in order to continue the chromatic scale downward 12 more semitones to around 8-foot bass G# [104 Hz] with no audible break.
What's important to understand about Conn pipes is that this invention, the way it disperses sound within the room, the gradual buildup and gradual decay of sound associated with it, and its efficiency compared with the power needed to run it, is old technology meant to work with conventional speakers and that its effects are most noticeable up close.   Up close the diapason and flute stops have more body, strings take on a subtle but brighter edge, reeds are also a bit keener, and the sound gets dispersed throughout the room to where it seems to come from every corner, adding to the quality and ambience of what the listener gets to hear.
Looking backward in time the general attitude of those with only cursory knowledge of or experience with these units is that they're merely aesthetic visual enhancements, a reference only to the sight perspective, not to their measurable audio or pneumatic effects.  This largely accounts for the wide sway of opinion about them.  Pricing of them today also seems to be all over the place and is mostly dependent upon their condition.  It's important to remember however that the sound from these units never gets out of the wooden base -- it all emerges at the tops of the pipes pointed at the ceiling (in the case of the model 146, a small portion of the sound also emerges about a quarter of the way up the pipes at the cosmetic notches).
Part of the reason certain owners fail to be impressed with this invention is that they test it by swamping its effects in an avalanche of other loudspeaker sound with high treble boost.  The signal stream being sent to the pipes from the amp is best kept FLAT with the treble of all other speakers turned down to allow the pipes to shine through and create the brightness for the whole organ.  It's easy to be fooled when the pipes are tested against ordinary loudspeakers pushed to the limits like this and nothing more seems to be reaching the ear.  Informed musicians from all over the country would not be spending, in some cases, hundreds of hours, traveling hundreds of miles, and spending hundreds of dollars plus a good deal of time, attention, and elbow grease searching to locate and obtain these units if, after they were hooked up, they did nothing but look pretty.

A few owners who couldn't be more indifferent about decoration have even introduced these speaker pipes into their home stereo systems or connected them to their electric guitars for the sonic effects they produce!

NOTE:  A reliable source, upon discovering and fixing a broken wire connection to ONE of the model 145s he had hooked up to his own digital practice organ, even though the instrument was already speaking through 2 other sets of 145s, 4 sets of 146s, and dozens of other loudspeakers of various sizes, he had to go back and reset ensemble combos stored on piston memory to compensate for getting this one lone set of 145s working again.  It made that much difference in the mid- and upper midrange resonance of individual manual voices to require some readjustments in the buildup to full organ.    There would have been no need for this, if window dressing was all these units had to offer. 
If the user knows how to take them apart, clean them, reassemble them, hook them up, test them, adjust the treble and volume of other speakers accordingly, and give them a fair hearing, the satisfaction they are certain to bring is not fake by any means ...

It's reality.

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