....vintage
studio equipment in a scene from "The courtship of Eddie's Father",
starring Glenn Ford..
Not much information can be found in
cyberspace about the original Rek-O-Kut company based in NYC. But the company
was a highly regarded manufacturer of turntables, tonearms and cutting lathes
during the golden age of Hi-Fi. A lot of these idler driven turntables found
duty in radio stations due to their quick start up time, stable speed and
simple yet well executed engineering. My 1961 Lafayette catalog lists several
idler models starting with the entry level 2-speed 4 pole induction motor
driven Rondine Jr. L-34 [33 and 45] and L-37 [33 and 78], 3 speed Rondine B12
with same 4 pole motor as the L-34/L37, Rondine Deluxe B12GH which uses the
Papst "flywheel" hysteresis motor and the the top of the line B12H
which uses the HUGE hysteresis motor [see picture below]. By 1963 the L-34/37
Rondine Jr. series was replaced by the N33/34H belt drive which usually was
fitted with the Papst motor. I have no experience with these models or motor
but they have a good following.
All the Rek-O-Kut turntables are a model of
engineering simplicity [no pitch control or eddy current brake] making the
Garrard 301/401 and Thorens TD124 look over engineered. The motor and idler
wheel arm assembly are individually isolated through rubber grommet mounts to
prevent extraneous vibration from reaching the platter. The control switch
physically moves the isolated motor with stepped capstan to engage the idler wheel
at a chosen speed. Surprisingly the budget Rondine Jr. model employs dual idler
wheels, the compromise being a simpler idler wheel arm assembly that does not
need to be moved up or down to engage the capstan. Building a massive plinth
for this model is very easy since it only requires a rectangular cut out to
accomodate the motor unit. Due to the simple design the condition of the idler
wheel[s] and rubber isolators as well as the few lubrication points have to be
addressed to insure optimum operation.
The spindle is
approximately 5/8" in diameter and comparable to those found in a TD124 or
301/401. The platter is a precision lathe turned aluminum weighing about 5-6
lbs. depending on the vintage [earlier models were lighter].
Pull out the platter and then remove [3 screws] the bearing well from the motor board. The inner rim of the platter and spindle should be cleaned and the bearing well should be flushed with lighter fluid or denatured alcohol. There should be a small ball bearing inside the bearing well. Inspect the condition of the ball bearing and if it shows signs of corrosion, replace it with a 1/4" or 5/16" ball bearing available from a bicycle shop. A brand new shiny ball bearing insures a smooth and silent turning platter. I am not sure what the original diameter of the ball bearing was but find that a 1/4" seems to turn a bit quieter than the 5/16" and the platter rests quite low on the top chassis which looks just like in the original brochures.
The motor assembly can be
removed from the top chassis by unscrewing the switch knob [1] and the
3/8" hex nut on the opposite side [2]. Now is the time to check the
condition of the rubber mounts [1& 2 below and two more on the other side
not visible] 4 of these are used to isolate the motor. If they are pliable and free from cracks just clean up all the grease and accumulated gunk. Replacement rubber grommet mounts are still available from Lord Corporation in Erie, PA although I have yet to encounter cracked or glazed rubber mounts.
After years of storage the top and bottom motor bearings' lubricant may have gummed up. Spray Electric Motor Cleaner and compressed air into the oiling turrets [marked with arrows]. Once the bearings are turning without significant resistance, light oil can be added.
To clean the idler wheel bearing remove the E-clip and flush the stud [1], brass bearing [2] and washers with lighter fluid. For reassembly the sequence [from bottom to top] is - thick washer, thin washer, idler wheel, thin washer, thick washer then E-clip. I use thin gun oil to lubricate the stud and brass bearing.
To clean the idler wheel bearing remove the E-clip and flush the stud [1], brass bearing [2] and washers with lighter fluid. For reassembly the sequence [from bottom to top] is - thick washer, thin washer, idler wheel, thin washer, thick washer then E-clip. I use thin gun oil to lubricate the stud and brass bearing.
Idler wheel condition is very critical for a quiet running ROK. Minute flat spot[s] in the idler wheel will definitely be heard as loud rumble. It has been suggested in the Vinyl Asylum that cleaning the rubber with lacquer thinner can rejuvenate a "not so tired" idler. With the platter off, turn on the motor and engage the idler while brushing the rubber wheel with a small paint brush dipped in lacquer thinner. Sometimes this trick will work but if the rubber hardens and becomes noisy when it dries up, it needs to be refurbished. It didn't work on this particular idler wheel set.
Worn out
idler wheel - the rubber is glazed and hardened, it also measures 1/32"
less than 2.5"
Refurbished
idler wheel is exactly 2.5" in diameter
The turntable is now
almost as quiet as my Garrard 301. Mechanical noise should not be audible 4 feet away from any idler driven deck in a quiet room. Another way to determine a worn out or
glazed idler wheel is to try grabbing the platter and if it stops easily or
does not offer much resistance the rubber is slipping.
According to the manual
SAE 20 motor oil is the recommended viscosity for the main bearing. I use non-detergent SAE 30 and you only need to pour in enough oil to cover the top of the ball bearing
and then rubbing some to the spindle before inserting the platter into the
bearing well. As pictured the tip of the 1/4" bearing I used is not quite
submerged in oil and needs a couple more drops.
This picture shows the
position of the set screws with rebuilt idlers installed and speed calibrated.
Although there is no pitch control in most ROK models, speed can be fine tuned
by moving the set screw along the arrow marked directions. The motor should
have been running for at least 15 minutes before adjustments are made. In
general it would be prudent to keep the idler to rim tension at a minimum
[closer to the knob] to prevent premature idler wear. Too much tension with
good idlers slow down the speed and generate more noise. Proper tension is
obtained when the platter locks in to speed within a couple of minutes. I use a
neon pilot lamp from Radio Shack soldered/heatshrink wrapped to a long AC cord
to view the stroboscope markings.
Other Models
Rondine Jr. L-37 and
LP743 - 3 speed
These are very similar in
design but the earlier LP743 has rather innovative features - the same idler is
used for 33 and 45 and the mechanical switch to the extreme right changes the
height of the idler to match the 33 or 45 rpm capstans of the motor. The idler
on the left is exclusively a driving wheel to spin [no contact with the motor
capstan] the platter at 78 rpm. However the idler arm on the LP 473 is directly
attached to the top plate so the idler is rigidly in contact with the inner rim
on start up whereas the L-34/37's idler arm is mounted on a substructure
isolated by 3 rubber grommets contributing to less mechanical noise but a tad
less kick on start up.
The bottom idler wheel
[marked with an arrow] is driven by the bottom capstan [78 rpm] in the motor
shaft which then transfers the motion to the top idler wheel to turn the
platter. This pair of idler wheels for 78 rpm are mounted using set screws
instead of an E-clip. The platter on the LP743 is slightly smaller and a bit
lighter but the main bearing dimension and quality are identical. Earlier
versions of the Rondine Jr. L-34 or L-37 also used this square type motor.
Idler wheels are not
interchangeable between the B12H, LP473 and L-34/37.
Rondine Deluxe B12H
fitted with a ROK S220 Gyropoise tonearm. This is the top of the line 3 speed
model using a single idler wheel. Notice the tool kit under the platter?
The tools are provided to
fine tune the speed and idler tension - the Allen wrench is used to remove the
big control knob and the hex wrench to loosen the hex nut to fine tune the speed.
As you slide towards 2 there is greater tension. Apply the same adjustment
procedure as noted in the Rondine Jr.
Top motor is the hysteresis
unit found in top of the line ROK machines, the bottom motor is from an L-37.
.jpg)
B12H stock plinth
Rek-O-Kut Rondine deluxe B12H after
restoration and idler wheel rebuild. Tonearms CW from left: Pickering 190, Argonne AR600 and Velvet Touch.
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| Rek O Kut L34 Rondine Jr. + SME 3012 + Excel ES801 DIY Plinth |
For more information and
discussion of Rek-O-Kut turntables visit the Vinyl Asylum Archives.
Idler Wheel rebuilders:
Idler Wheel rebuilders: