telefunken: 8; Concertino. Equalization keys etc.

Good morning fellow radio enthusiasts!

I recently bougth a Telefunken Concertino 8 in Germany to replace another FM radio in my house that got broken and will take a very time-consuming repair.

First of all please let me express my admiration for the german radio industry of those times and the goals it achieved with outstanding products like the Concertino series. I am impressed by the overwhelming quality of this radio and by all the facilities with which it is equipped. The sound especially left me literally open-mouthed. The rotating ferrite antenna is another great feature.

Now to my question. It seems to me that the only "usable" setting for the equalization buttons is the "orchestra" setting. With "jazz" and "solo" my unit emphasises the high frequencies to such a point that the audio gets extremely fatiguating. Low frequencies are emphasised as well, but not as much as the high ones. In addition, the "treble" control, which is very effective when the radio is used in the "orchestra" setting, seems to have almost no effect when in "jazz" or "solo" mode. The bass control, instead, always effects the sound as it should.

I would like to read other owner's impressions on this topic. Is this expected? Perhaps those settings were designed to be used on AM broadcasts, where high frequencies are much less than in FM and thus need to be emphasised? Or does the equalizer of my unit definitely need to be checked?

Thank you.

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Hello Marco, I have this radio and it does have magmificent sound. The bass and treble controlls on mine only function in the "orchestra " position, and from what I can work out that is the way it is intended.I  was wondering about that myself, perhaps someone else has some info on that? I usually keep it on the "bass" setting when playing at low levels,and use "jazz" which emphasises treble with less bass if I want a bit more volume, as the high bass drains too much power and distorts too much if playing louder. I use "orchestra " a bit if i want to manually controll the equalisation. The "solo" is quite flat and suitable for hearing a voice/news or something clearly. It is worth dismantling and cleaning all the contacts on these switches so you know they are working correctly. Let me know how you get on with restoration! 

Stuart  

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Dear Marco,

yes, FM German radios were true high-quality sound systems. Every circuit was carefully designed with no compromise, and the same was true for the speaker system and for the cabinet. Their only imperfection was the FM band limited to 100MHz for the domestic models. I have no experience with this model, but I often use a Telefunken Opus 2430 UKW or a Hymnus Hi-Fi Stereo 5014WK, US version that tunes up to 108MHz, to enjoy classical music. I find that their sound is excellent, even when I listen to deep and loud pipe organ performances.

The audio circuit of good quality German radios usually has two major tone control systems. The first one uses two potentiometers to manually enhance or attenuate trebles and basses. The second one uses register keys to have more or less fixed response curves. Usually there is also one hidden response control depending upon the listening level, the physiological volume control. When you select a particular register, as the ‘Solo’ or ‘Jazz’ or whatever named, you are bypassing the tone manual controls. You are giving the amplifier a response best suited for, say, reproducing the sax sound, but cutting at all the deep bass notes. In general the combined effect of tone controls and of register keys results in an overall attenuation of some high or low notes. In some radios, as many Graetz models Melodia, Sinfonia or Fantasia, the backlights of both manual tone controls are switched off when any tone register key is depressed. I never examined in details their circuitry, but this means that the manual tone controls are ineffective when registers are switched on.

To have the best sound you should not use register keys at all, unless the ‘Orchestra’ position gives simply a flat response.
 

Enjoy your radio, Emilio

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Hello Stuart and Emilio and thank you for your kind replies. I took some time to check the schematics this weekend (it was placed in the back panel inside a cardboard pocket, what a nice touch from Telefunken!) and it seems you both are right. Although not easy to read out, both tone controls are bypassed with a switch when anything but "orchestra" mode is selected.

My impression that the bass control was always on was probably due to a bad contact, or a wrong acoustic impression. I redid some careful testing yesterday and it's definitely off as well.

I agree with Emilio that these pre-set curves are not very impressive. The emphasis is much exaggerated; it may have impressed casual customers of the time but it is seldom useful under normal listening conditions. But perhaps radio broadcasts of the time had a different frequency range.

I listened to the radio all through the weekend and I am delighted, I will never part from my Concertino! I agree that the extended UKW band could be a nice addition, however I can live with 100 MHz as RAI 1, 2 and 3 are all below that frequency, I only miss the Filodiffusione channel 4 which is over 100 in my area, but you can't have everything, right? In change, there is the LW band which is almost always omitted in italian radios and with which I can very easily tune in the interesting french broadcasts.

Emilio, do you perhaps know of italian radios of the time that reached this level of perfection? I must admit that I always undervalued radios of the fifties/sixties because of the pitiful quality of the italian radios with which I have to do almost daily. I first got the impression that there was a part of the world I was missing when a customer brought in his Blaupunkt Arizona for repair and I saw how well it was made. This Concertino (and some other radios you have linked to, like the Graetz with the horn driver: impressive!) again changed my point of view.

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Dear Marco,

the purpose of register keys can be partially explained considering the state of art of broadcast transmissions in a given period. Early FM radios were just AM sets with an added FM tuner. Very soon the audio sections became evolving, to match the increased bandwidth available both from the music sources, tapes and microgroove records, and from the FM broadcast equipment. German radios first were equipped with one or more additional electrostatic speakers and then with some dynamic mid-ranges and tweeters, to increase mid and high-frequency response and offer space-surround or full stereo sound. But all the audio section was carefully designed to give high-quality sound extending to some 15KHz. The cabinet itself and the high-compliance speakers were all part of the audio system, in a sort of high-efficiency speaker enclosure. Here you can find a poor (space-limited), yet significative overview of the evolution of FM German tube radios through the years.

With audio sections designed for FM, register keys had some usefulness when listening to other sources: ‘Voice’ key could be useful in AM reception to attenuate high-frequency noise, hiss or heterodyne whistles; ‘Jazz’ probably was used in record reproduction to mask-off rumble from the turntable. Today broadcast stations on AM bands are closing out and shellac or vinyl records are no longer in use.  So, you can just listen to FM sources and register keys are useless.

In my opinion, Italian radios, when compared to the German sets, are just rubbish and often also harmful rubbish. When looking to the inside of them, the first sensation is to see a handful of components placed here and there inside the cabinet: no care for the acoustics, for service accessibility or for cooling-air flows. The cabinet itself, apart from its more or less attractive look, was of soft and often worm-eaten wood. Even simple solutions, popular in German radios, such as the tuning flywheels, the separate AM/FM tuning dials, the built-in ferrite antenna, the dual tone controls or the loudness (physiologic) volume control, are not available in Italian sets. Circuits are elementary, also in big sets with 8, 10 or more tubes. Try to give a look to the diagrams of top models from the major brands, Allocchio Bacchini, Ducati, Geloso, Imca or Marelli: no complex audio filters, no loudness, no feedback loops, no RFI filters, no safety devices, as simple fuses. Components were usually of poor quality and not safe, when used in critical applications. In my experience, almost all the electrolytic capacitors were fully dried, almost all the paper capacitors were leaky, and several mica capacitors were out of tolerance. Most of the ANIE approved sets did not use power transformers and the urea plastic knobs were often crumbled or broken, leaving hot metal parts exposed. In some sets I found asbestos sheets under the cabinet ceiling to prevent fire from too close power tubes.

I am sure that you will appreciate more and more the quality of your radio. May be that very soon you can find one of the latest German tube radios, those with stereo decoder inside and with FM ranging up to 104 or 108MHz. They have a sound quality not far from the best hi-fi equipment and fully compatible with the quality of the available FM sources.

After all, today the ‘Filodiffusione’ channel plays the finest classical stereo music!
 

Regards, Emilio

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Hello Emilio. Unfortunately I have to second your sentiments about italian sets made after WWII, from which descended my (now reviewed ) dislike of sets of the fifties. Let me just add to your list the vast use of zamak in some parts: an alloy that one would prey had never been invented. Dried-up crap would probably be more resistent.

I agree especially on your point about maintenance and repair. This has always been an awfully weak point of italian sets, and it got worse and worse during the 50s and the 60s.

Thanks for the link: it has been a very nice reading and a very amusing survey over many beautiful sets of that era. Too bad that when stereophonic broadcasts were introduced, the aesthetics of these radios became objectionable (at least for my taste, obviously). One can only imagine the wonders of a Concertino 8 with a stereo decoder!

With my best regards, Marco.

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