SIEMENS Schatulle M57

The Siemens Schatulle was produced between 1955 and 1957 and it was of the best and most successful models of the entire Schatulle series. Although the number of sold items was smaller if compared to the smaller and cheaper H42 and although it was not as huge and well-sounding as the P48, this was certainly the most well-balanced model under many aspects.
Further on I will explain why.


- The power stage is as big as the P48’s, a couple of Push-Pull EL84, a sophisticated counterreaction system, physiological volume control, separated high- and bass controls
- it is equipped with 4 loudspeakers. Differently from the P48, the M57 is equipped with two bicone widebands and two tweeters with acustic drive. That makes the reproduction particularly refined and linear.
- Its dimension are midway between the H42 and the P48 making the M57 easy to place and at the same time majestic. Moreover the length/height ration makes the appearance of this device extremely pleasant although being rather big.
- Differently from other models, this device can be turned on and off and the volume can be regulated even when the small front shutters are closed.

None of the other Schatulle models is characterized by these elements. This is the reason why the Schatulle M57 belongs to the top quality Siemens production.

This device is best to be listened in on in a spacious room and played out loud.

The tuning stability allows the last station to be perfectly centered after days.

The mechanics is “simple” but robust. The electronic parts are rather complex, but completely restored.
Other features will be further described down below.

CARATTERISTICHE PRINCIPALI

Year of production: 1955 / 1957

9 AM Circuits
14 FM Circuits

Wavebands:
Medium Waves (OM)
Long Waves (OL)
Short waves (OC)
FM (UKW)

Power supply (AC)
110; 125; 160; 220 Volt

2 two 8" dual cone wideband
2
two 4" cone tweeters

Dimensions (LHD):
27 x 18.3 x 13 inch

Net weight: 42 lb 15.2 oz

Tubes 11:
EC92 EC92 EF89 ECH81 EM80 EF89 EF80 EABC80 ECC83 EL84 EL84

ORIENTAMENTO ANTENNA

Inside the cabinet there is a dipole for FM reception and a ferrite rotating aerial for AM reception.
The ferrite antenna rotates by means of a large knob situated on the left side of the main display.

The reception sensitivity with internal aerials is very good.

Using an external aerial sensitivity is further increased.

This unit was in fact produced in a period when there were not many radio stations and those available fairly apart from each others.

TONE CONTROL WITH LEVEL INDICATION

The tone control system is very efficient. Above the large tone control knobs there is a band that lights up gradually indicating the emphasis on the band on which it acts.

SEPARATE CONTROL PROGRAM BETWEEN AM AND FM

The tuning system is another gem.
The unit is equipped with mechanisms for keeping separate the AM bands by the FM bands.
The tuning knob is single but a selector switch commutes into cable systems (all in steel) and pulleys separated depending on the band.

The knob outside the shutters has a double function:

- On/off button (push)
- Volume control (turn)

You can therefore easily avoid to open the shutters to control the device.

The outer knob glows red when the radio is turned on.

The shutters’ cladding canvas needs to be acoustically as transparent as possible. It is a robust but holed canvas in order for the light to go through.
If you closed the shutter when the radio is on the effect created by the visible rear lights would be rather unpleasant.
Siemens solved this:
- When you close the left shutter the magic eye turns off automatically
- When you close the right shutter the lightning of the dial scale switches off

The device is equipped with a double-position equalizer commutator :

Musik – the entire sounding spectrum is reproduced
Sprache – only the central part of the spectrum is reproduced.

The indicator lightens up on the scale when in Sprache position.



L'occhio magico è nuovo.

CONTROL PANEL

The controls are placed in an unusual way.
On the left there is the rotation control of the ferrite curve.
On the right you can see the magic eye indicating the perfect tuning of each station.
Below the magic eye you can see the equalizer indicator Sprache/Musik above mentioned.
Then the Short, Medium and Long Waves AM scale is to be found together with the differently colored FM scale.
Lastly you can see the tuning knob, whose two supporting big fly-wheels make its movement very pleasant.
Below you can find the bass control knob.
In order then: the Sprache/Musik, record player, Long, Short and Medium Waves, ferrite curve, OM narrow band and FM commutation buttons.
Lastly, on the right, the acute control knob.
The illuminated small knob outside the shutters allows the volume control (with incorporated loudness)

LOUDSPEAKERS


There are four louspeakers.

Two 21 cm (8.2 inches) very efficient bicone and known by experts using these louspeakers to create amplifiers.

The radio is equipped with two cone tweeters assembled on the acoustic lens.
That creates a pleasant ambience and a side diffusion as widespread as possible.

REAR SIDE

Output for external speakers.

Socket for recorder (tonbandgerat).

Turntable input (Tonabnehmer)

AM and FM antenna inputs and ground socket.

RESTORATION WORKS

As it used to be.

The partially cleaned chassis.

You can see the part where the cleaning up has already been made

The electronic section before the restoration
The complexity of the electronic parts.
 
 
 
The substitution of the socket
The capacitors are substituted completely because they are altered even though not yet in dispersion.

An example: in the picture the condensator has a 500 pF marked capacity but a 1411pF real capacity.
Some of the substituted components.
Completed restoration.

Polarizations tests.

The rectifier bridge is at a loss.
Here is how it should be reactivated.
The the polarization tensions need to be realigned.
Now it is ready to work.
Sound tests.
The extremely original rectifier bridge.
The calibrating phase.
The test of all the tubes.
Now it is completely working
The frontal panel after the dry cleaning.
The beautiful loudspeaker groups.
The cabinet delivered right after its restoration.

The usual final overnight.


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Email: Giovanni - Cell: +39.331.6016062

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