How to stop audio in 3d device

Capella Reverbeo B7X43A

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philips: B7X43A (B 7 X 43 A); Capella ReverbeoUwe Müller
April 20, 07  1
Hello dear collector friends,

At this point a few `pertinent` information on the repair / restoration of the Philips-Capella-Reverbeo.

Since the structure of this device has a few peculiarities, it is certainly not wrong to point them out here. Anyone who has never had to repair a device of this type will experience the first surprise after removing the back panel. After that, not much happens, i.e. no access to the interior is possible here. One looks at the reverberation spiral, hidden in a U-shaped sheet metal and suspended from the chassis. It is absolutely not recommended to want to dismantle it, e.g. E.g. to change tubes quickly! The reverberation spiral looks like two very long ballpoint pen springs and works (to put it somewhat simply) as a kind of electromechanical system with a `transmitter` and a` receiver`. The really difficult thing about it are the two tiny transformers, which are located on the right and left at the connections of the spirals. In the healthy case, these transformers have a resistance of approx. 170 ohms. If you simply unhook the suspension springs of the spiral and let them hang on the connecting strands, it can happen that the extremely thin wire of the transformer is torn. You hardly even see the wire against the light and it is very tedious to repair the damage! For the spiral to function properly, the U-plate must be able to move freely and only hang on the four suspension springs. Otherwise there will be awful acoustic feedback from the bass of the speakers! In this context, a note on the ground screws: if you turn the device upside down, you can see 8 screws. If everything is still original, there are paper flags on four screws with the note "Loosen this screw!". These four screws are only transport locks and only hold the rubber-mounted chassis in place during shipping! They should definitely be loose, otherwise the rubber suspension is pointless and under certain circumstances, `throbbing bass` from the LS is undesirably transferred into the structure. The other four countersunk screws hold the metal rails of the `suspension`.
If it is necessary to dismantle the chassis, all 8 screws must of course be removed. Furthermore, the wooden front strip (4 slotted screws) must be unscrewed, because the chassis only comes out towards the front!
You have to lift it a little carefully and first pull it out a little before unsoldering the speaker connections. Then carefully “circle” a little at an angle to get past the speakers' magnets. In order not to take any risk, you can dismantle the dial beforehand. To do this, remove the gold-colored cover strip at the top, the large control buttons (plugged in, attention: spring clip!) And the small buttons of the height / depth regulator (grub screws in the potentiometer axes). Incidentally, treble and bass control only work if no key of the clan register is pressed!

Then you can usually already see another `gift`, the famous / notorious electro-luminescent disc of the scale illumination.
Unfortunately, this is now defective in most of the devices in the series, burned through by penetrating humidity at the edges of the two glass panes. Since this disc is supplied with 265V AC from the anode winding, it sometimes tore the transformer to its ruin.
I had to look for an adequate replacement for a long time and came to the following result:
The closest thing to the original are so-called luminescent foils, which work in the colors white, green and turquoise, depending on the operating frequency. So they come into question, the original screen shone (phosphor) blue-green. The foils work with voltages of approx. 120V AC, but with more than 50Hz and can therefore only be operated with an inverter. (Supplied with the foils by the supplier) So you have to build a kind of `power supply`, luckily there is enough space in the device for this box. Unfortunately, the necessary output frequency of the inverter brings the devil into the house in the form of hum interference. It must therefore be fully shielded in order to avoid interference as far as possible. I soldered the umbrella box (9x16.5cm) made of lyre plate material and built it into the base plate cover cardboard.
The luminous film is stuck onto a 9.5 cm x 23.5 cm x 0.5 cm glass or plexiglass carrier with double-sided adhesive tape and it hardly gets warm. The inverter works with 12V DC input voltage, so I built it together with an EI 48 print transformer (230V prim / 12V sec) and rectification / smoothing on a breadboard and installed this isolated with spacers in the screen housing.
It would theoretically be possible to take the supply voltage from the 6.3V heating circuit using a voltage doubler circuit, - but: the power requirement is 500mA and whether the transformer heating winding is happy about half the A more is questionable.
I took the power supply of the transformer from the power contacts to the primary winding of the transformer (easily accessible on the button set). However, it still has to be via a small microswitch that I installed behind the Reverbeo (reverberation) button on the sound register, so that it interrupts when `Revebeo` is pressed (opener). Because despite the fact that the interference suppression is otherwise quite successful, in the case of reverberation, an oscillation tone is created through LF transmission from the inverter to the reverb spiral. So it's better to switch off the lighting when you want to reverberate. I bridged a high-quality capacitor of 450 nF via the output of the inverter (approx. 120V DC), important! this brings the frequency to 485 Hz, the best compromise between luminous brightness of the film and interference.
No interference is perceptible on FM or in TA mode, and neither on MW at normal transmitter levels, but unfortunately unavoidable on LW. (In my opinion, this is bearable, since LW is certainly rarely used.)
Certainly this is a “Kalashnikov” solution, but unfortunately it is almost hopeless to find an original replacement disc today. And it is precisely the special feature of the dial lighting that makes up an essential part of the device.
When viewed from the outside, the result is an original scale light experience and it is worth the work!

Since I do not know whether the reference address of the film manufacturer may be given here for legal reasons, please send me a short email if you are interested.
If someone should have found a better solution, I look forward to your response!

With best regards! Uwe Müller

Rolf Nickel
Apr 21, 07 2 dear friends,

To supplement this article, I am attaching a brief explanation and a circuit diagram, taken from RPB 7/8, Franzis Verlag, 13th edition 1970, Fritz Kühne, low frequency amplifier with tubes and transistors.

Incidentally, there are hardly any traces of Fritz Kühne (* 1910), as of the other "older authors" in the Radio-Praktiker-Bücherei (RPB). Since he was a radio amateur (DL6KS), I was able to discover his name in a list of the members of the DARC local association of Garmisch-Partenkirchen who died in 1982 ...

More information can be found here:

1. about the RPB
(Thank you for that, Mr. Grabau!)

2. via Fritz Kühne

I agree with Mr. Erb's opinion, dear Mr. Müller, I had completely forgotten that in my delight at your contribution.


Ernst Erb
Apr 21, 07  3

Many devices have their own peculiarities and specific potential for errors. Such contributions are extremely important, especially for beginners. We want to encourage the next generation and prevent devices from being messed up.

That is why I occasionally call for you to describe your repair experience with the model. You can do that at any time, even without editing rights (because first post of a thread) - and then also reply.

I congratulate you, Uwe Müller, on your contribution, which goes well into the problem at Reverbeo - and of course you can name the source of the film manufacturer here, that helps everyone - including the guests who read this. Perhaps you could loosen up this longer text with subtitles etc. and subdivide one or the other long section? That reads much better then. The next step would be integrated images - but it may be too late for that. Thank you, Mr Nickel, for the outline illustration.

Reverberation devices in radios were really rare and their installation only took a short time (also associated with various technologies, e.g. purely electronic). Please track down such models and list them in this post - if necessary via email to a poster here. For Philips we list 3 models in D and 4 in NL. Via SEARCH I found the New York 4540 from Blaupunkt (1958!) With reverberation amplifier (circuit 1b below right). For music enthusiasts there were separate (also mechanical) reverberators or "falsifiers" ;-) Who can still create such?

The device is called Reverbeo, because reverb in English means "reverb" or reverberation "reverberation".
In contrast to the echo generator, a reverberation device or a room hall device (room reverberation device) produces continuous reflections of sound waves, so-called sound reflections, which follow each other for less than 100 milliseconds. In the case of an echo, these are longer delays. Effects devices can create both - but also change levels, distort, etc.

A natural one echo comes from a (or very few) reflective surface, reverberation from many sides (diffuse). A natural reverberation is created by rooms (halls - because they reverberate) with hard surfaces such as mirrors, marble, stone etc. In recording studios in apartments, offices etc. one tries to avoid echoes and reverberation. At large concerts, a reverberation of 1.5 to 3 seconds (one thousandth of a sound pressure) is perceived as pleasant. The Reverberation time is proportional to the volume of the room and inversely proportional to the equivalent absorption area.

Addendum (editing):
This is about the Grundig models that are suitable for room hall furnishings and this is about the Phonomascope room reverb (a Hammond reverb spiral). Here this room reverberation facility with reverberation spirals from SABA.

Karl-Heinz Bradtmöller
Apr 21, 07  4


Further information on Grundig Ehrenfels hall equipment (installation instructions) can be found at

Model ID = 26336 more plans


ID 152864; 70 kB (11/06/2005; Uploader K.-H. B.)

Furthermore, it can be seen from the picture of the front panel of the radio part that the device was prepared for reverberation as standard. The adjuster for reverb is usually locked with a pin, but is always to the right of the desired sound register (bass-mid-treble).

Best regards

Your K.-H. B.


Jens Dehne
Apr 21, 07  5

In the 1962/1963 season, the top-of-the-range Graetz devices (Polonaise 41114, Grazioso 41118, Moderato 61118, Scerzo 71118, Belcanto 81120, Maharadscha F583, Maharani F593) were prepared for the subsequent installation of a room hall facility type 1161.

In the following season the HF stereophony came and the "artificial" room reverb was history for home applications.

Best regards!

Jens Dehne

Franz-Josef Haffner
Apr 21, 07  6

Under the search term "Sonorama" you will find the models from Saba with hall equipment or the Sonorama hall devices model 11 and model 14.

I was able to save parts of a Bodensee 12 Sonorama chest from disposal and put the chassis and Sonorama 11 unit into operation.

I actually assumed that the reverb spiral with its narrow frequency band had a negative impact on the sound, but was taught better. The electronics apparently only echo certain frequency ranges. The reverb effect is infinitely adjustable, and if you only adjust it slightly, the Sonorama unit can enrich the sound image.

The body of the reverberation spiral has the considerable width of 42cm!

As a system, my experimental set-up. The brown housing of the spiral spring unit can be seen above the chassis.





Franz-Josef Haffner
April 22, 07  7

Otmar Jung has researched a contribution to the beginnings of plastic hearing and asks me to publish it.



Schneider, radio internship, Berlin, 1926

Room listening



Karl-Heinz Bradtmöller
April 22, 07  8

Hello Mr. Haffner,

the reverb springs were also cheap to buy back then. So I reverberated a number of my own instrumental recordings (mandolin). (Grundig TK 17 track 1 mandolin dry - track 3 with reverb - overdubbing). The quality is not bad. The digital devices in the same price class (bucket chain storage) were by no means of comparable quality and brought a number of undesirable artifacts, intermodulations, changes in pitch when adjusting the reverb depth, etc., so that I really enjoyed working with the reverb spring. This is the only way to reproduce a typical "electric guitar sound".

Just by the way. The Hall springs z. B. the Grundig radio reverb processing are excellent.

However, one should not take the current state of exciters or enhancers or surround sound processing as a yardstick.

Best regards


K.-H. B.


Konrad Birkner † August 12th, 2014
April 22, 07  9

Philips Capella Reverbeo 8D54A has stereo (decoder) and built-in reverb, which works very well with sensitive dosing. With language it is easily too much, but with classical / chamber music / jazz it is quite pleasant. And that still in the mid-1960s!

Mark Hippenstiel
Apr 30, 07  10

Mr. Müller asked me to publish his following post:

The reference address of the manufacturer for luminous films:

Lightec GmbH
Rüdelsweg 3D
96050 Bamberg

Tel. 0951/981110
Fax 0951/9811199

Email info [A * T]

In addition, a write error had crept in, the output frequency of the inverter is 584Hz, not 485Hz as stated in the article.