Magnetic coupling

Re: "cassette adapters" that deliver (audio) content
directly to the head in a cassette player/recorder.

(From photographs -- have one on order to examine), these
seem to just be conventional heads mounted to coincide
with the head to which they are intended to couple.

There doesn't seem to be any sort of lubricant/insulator
between so metal-to-metal (?)

I would imagine the driving signals are of very low
amplitude so no need for actives in the "adapter"
(if driven by a "line out").

And, the cassette housing is intended to precisely control
the position of the media wrt the (playback) head so I
assume that information is leveraged to ensure alignment
of the head in the sensor.

Any other "hidden magic" to consider?

On Mon, 15 May 2023 14:29:59 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

>Re: "cassette adapters" that deliver (audio) content
>directly to the head in a cassette player/recorder.
>
>(From photographs -- have one on order to examine), these
>seem to just be conventional heads mounted to coincide
>with the head to which they are intended to couple.
>
>There doesn't seem to be any sort of lubricant/insulator
>between so metal-to-metal (?)
>
>I would imagine the driving signals are of very low
>amplitude so no need for actives in the "adapter"
>(if driven by a "line out").
>
>And, the cassette housing is intended to precisely control
>the position of the media wrt the (playback) head so I
>assume that information is leveraged to ensure alignment
>of the head in the sensor.
>
>Any other "hidden magic" to consider?

I use one of these in one of my cars.

Now you have me wondering if there is any spacer between the two heads
?   I will look.

There must be some space in order not to hurt it so you can still play
a tape.

I do notice that the level going into the head has to be reduced which
makes sense to reduce distortion.

boB

On Monday, May 15, 2023 at 2:30:10 PM UTC-7, Don Y wrote:
> Re: "cassette adapters" that deliver (audio) content 
> directly to the head in a cassette player/recorder. 
> 
> (From photographs -- have one on order to examine), these 
> seem to just be conventional heads mounted to coincide 
> with the head to which they are intended to couple. 
> 
> There doesn't seem to be any sort of lubricant/insulator 
> between so metal-to-metal (?) 
> 
> I would imagine the driving signals are of very low 
> amplitude so no need for actives in the "adapter" 
> (if driven by a "line out"). 
> 
> And, the cassette housing is intended to precisely control 
> the position of the media wrt the (playback) head so I 
> assume that information is leveraged to ensure alignment 
> of the head in the sensor. 
> 
> Any other "hidden magic" to consider?

I suspect that a spring  holding the heads in contact is weak enough that
a scratch cannot reasonably result.   Also, the readout  head has a very low impedance 
amplifier attached, so the equivalent of a 1:1 current transformer is being assembled
when the dummy tape is inserted.

Thus flows terpsichore's signal.

On Mon, 15 May 2023 14:29:59 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

>Re: "cassette adapters" that deliver (audio) content
>directly to the head in a cassette player/recorder.
>
>(From photographs -- have one on order to examine), these
>seem to just be conventional heads mounted to coincide
>with the head to which they are intended to couple.
>
>There doesn't seem to be any sort of lubricant/insulator
>between so metal-to-metal (?)
>
>I would imagine the driving signals are of very low
>amplitude so no need for actives in the "adapter"
>(if driven by a "line out").
>
>And, the cassette housing is intended to precisely control
>the position of the media wrt the (playback) head so I
>assume that information is leveraged to ensure alignment
>of the head in the sensor.
>
>Any other "hidden magic" to consider?

Equilization. The playback head goes through some radical frequency
compensation, namely tons of low frequency boost, so the adapter drive
electronics has to have the opposite response.

I'd expect the mechanical and magnetic design of the adapter head to
be different from the playback head, namely wider gap, but that's a
guess. It should be visible.

On Monday, 15 May 2023 at 22:30:10 UTC+1, Don Y wrote:
> Re: "cassette adapters" that deliver (audio) content 
> directly to the head in a cassette player/recorder. 
> 
> (From photographs -- have one on order to examine), these 
> seem to just be conventional heads mounted to coincide 
> with the head to which they are intended to couple. 

yup

> There doesn't seem to be any sort of lubricant/insulator 
> between so metal-to-metal (?) 

no

> I would imagine the driving signals are of very low 
> amplitude so no need for actives in the "adapter" 
> (if driven by a "line out"). 

right, just the head

> And, the cassette housing is intended to precisely control 
> the position of the media wrt the (playback) head so I 

for some sloppy value of precise

> assume that information is leveraged to ensure alignment 
> of the head in the sensor. 

??

> Any other "hidden magic" to consider?

https://youtu.be/dH4n8fUjtLQ