This is a very interesting data point!
Does the RX-202 rely on the built-in pressure pad to maintain good
If we visualize a Venn diagram and we have an overall circle called
"Soft Binder Syndrome" and completely enclosed within that circle is
another circle called "Sticky Shed Syndrome" your tapes would fall in my
taxonomy outside Sticky Shed Syndrome but within Soft Binder Syndrome.
It is, in fact, exactly this case (for reels and cassettes) which caused
me to develop the concept of a taxonomy for these failure mechanisms
that is, at least in part, based on effective restoration techniques.
In general, the type of squealing that you describe is not improved by
baking, which is why it is not Sticky Shed Syndrome.
Now, why your data point is very interesting is that no one I have
discussed this with has tried a tape which squeals on a higher-end Nak
deck on a simple two-head transport as you just did.
My first reaction to this discovery is that it fully reinforces the Soft
Binder Syndrome theory because the tape is, perhaps, not pressed against
the heads with as much force as in the dual-capstan design.
Additionally, it is possible that since the dual capstans are NOT
running at the same surface speed (the feeding capstan is running
slightly slower than the takeup capstan, though which is on speed may
vary--see note below).
So, with less force and potentially less tension-related deformation
(which may or may not aid in depositing the hooks onto the head that
ultimately cause the squealing) it is easy to comprehend why the RX-202
can play the tape.
The squeal is stick-slip between the tape and the head and often does
not start immediately (though you have not said whether yours does). If
it does not start immediately, then it is often caused by little pieces
of binder being deposited on the head and then acting as the hook on the
head side of the interface that actually connects with high points
(asperities) in the tape and causes the sticking which then a few
microseconds later slips.
The entire construct is not much different in concept (but, of course,
in scale) to the slippage of tectonic plates past each other. The squeal
is, of course, a high-frequency variation in the speed of the tape past
the heads and why it prints to the transfer in most cases. If the squeal
were not frequency modulating the audio, and was just annoying to the
transfer technician, then it wouldn't print (or print as much) to the
So, your experiment may be another option in treating squealing
cassettes. I had a similar experience with squealing reels and found
playing them faster and on a different machine helped.
As an aside, I have been led to believe over the last decade that this
squealing cassette tape that was bulk-loaded into cassettes for
duplication purposes (i.e. duplicated from pancakes and then loaded) is
an Agfa product, but I have no hard proof.
NOTE on dual capstan configurations: I was recently thinking about
dual-capstan configurations and did a little digging.
There appear to be two major modes of operation, but one is quite
interestingly subdivided. Note that the concept of dual capstans also
applies to single capstan machines with a "U" tape path where the
capstan contacts the tape both going in and coming out.
Dual capstans that run at different surface speeds:
This group is more widespread, I believe. There are many topologies that
cause this to happen.
(1) The 3M reel-to-reel machines used a single capstan with two
different diameters and the stepped pinch rollers pinched into the
smaller diameter on the input side and the larger diameter on the output
(2) Two physical Capstans
(2a) Unidirectional transports often use two capstans driven by a belt
where either the capstan diameter or the pulley diameter is different,
creating the differential. The Nakamichi MR-1 is an example of this.
(2b) Bidirectional transports often use two separate capstan motors
where the speed control of the individual motors governs the tension.
Where this gets complicated is I had always believed that the output
(takeup) side capstan pulled the tape at the proper speed while the
supply (input) side capstan provided drag. I recently found out that the
Studer A80QC reel-to-reel cassette tape quality control player sets the
supply capstan for the proper speed and the takeup capstan runs a bit
fast to set the tension. This leaves me totally confused. I have not yet
seen a definitive writeup (leave it to Studer to fully explain something
in their manual) on the Dragon as to which runs on speed.
Further to this, Studer switches which motor is connected to which servo
card on the A80QC while I think the Dragon just sends a different
control signal and the servos are mated to their specific motor. The
Studer approach, while relay-intensive (these are AC servo motors),
means that if the capstans are truly the same diameter (this is a Swiss
product, remember), then the forward and reverse differentials are the
same and there is no ambiguity as the actual supply and takeup servos
are always in that position.
Dual capstans that run at the same surface speed:
While the topologies vary, the concept is the same as I understand it.
The simple thing is that while the capstans filter the reel tensions
from the head loop, ultimately, the incoming and outgoing reel tensions
also translate to the tensions within the loop because the tape deforms
while passing the capstans, especially with pinch rollers.
The topologies are:
(1) Single capstan with two pinch rollers like the Technics RS-1500 (a
U-shaped tape loop)
(2) Dual capstan with pinch rollers (I don't know for sure of any as
it's too easy for two separate capstans to run at different speeds
(3) Dual capstans with three-point tape wrap, but no pinch rollers. It
seems that pinch rollers were removed more from instrumentation
recorders than from audio recorders. My 1970s Honeywell 101 machines
have two capstans that must rotate at the same speed. The tape comes
over a roller, a partial wrap around one side of the lower capstan, up
past the record head, a 180 degree wrap around the upper capstan, past
the repro head, and a partial wrap around the lower capstan and over a
roller out to the takeup reel (on the same axis as the supply reel!).
These two capstans are tied together with a non-elastic belt (stainless
steel) with one motor driving the upper capstan (if I recall correctly)
and the lower following. The input and output rollers are there to make
certain there is wrap around a portion of the lower capstan. The capstan
ramps up (quickly) for play or wind (there are no tape lifters). The
transport is effective.
Anyway, that's what I think I know at the moment for the concept of tape
squeal and the generation of tape tension using two capstans.
On 2014-02-06 5:55 AM, Shai Drori wrote:
> I am transferring a whole bunch of tapes for a client and found
> something interesting. Tapes made by SKC from the 90's will squeak in
> all my decks (Naks included) except for the RX-202. It's a 2 head design
> with one capstan. The closed loop Naks squeak like a cat in heat. I
> think it has to do with tension and head geometry. Any thoughts?
-- Richard L. Hess email: [log in to unmask]
Aurora, Ontario, Canada 647 479 2800
http://www.richardhess.com/tape/contact.htm Quality tape transfers --
even from hard-to-play tapes.