Siemens TR14 schematic - what does this symbol mean?

[rock soderstrom]

Hi group, I am fiddling around with this big lady. What does this symbol in the red circle mean?


Some kind of adjustable capacitor?

 

[Chandra]

To me it appears to be a electro static speaker. But not sure. Regards.

 

[Bo Deadly]

To me it appears to be a electro static speaker. But not sure. Regards.

I also initially thought was some kind of high impedance speaker but 50pF into 100K is 30kHz so I can't see how audio frequencies could reach it. The 100K is grounded through the screen filter cap so it's not somehow higher Z at AC.

 

[mad.ax]

Maybe some capacitor or transducer mounted into the speaker that provides feedback to the screens of the output stage?

We don't know the name of this "big lady"...? A peek into its documentation might give some clue.

 

[abbey road d enfer]

I also initially thought was some kind of high impedance speaker but 50pF into 100K is 30kHz so I can't see how audio frequencies could reach it. The 100K is grounded through the screen filter cap so it's not somehow higher Z at AC.

Signal from the plate of the bottom EL84 goes through the 50pF to the electrostatic tweeter. The 100k resistor is there to provide the necessary DC bias. The capacitance of an electrostatic tweeter is a few 100pF, so it receives about 1/5th of the AC anode voltage.

 

[abbey road d enfer]

We don't know the name of this "big lady"...? A peek into its documentation might give some clue.

Looks like one of the typical German radio/phono combos that were so popular in the 50's and 60's.
What's unusual is the complement of 3 woofers, 2 mids and one tweeter.

 

[rock soderstrom]

To me it appears to be a electro static speaker. But not sure. Regards.

That was also my first thought, but I discarded it, because I expect something like that at the OT with a mini crossover.

Maybe some capacitor or transducer mounted into the speaker that provides feedback to the screens of the output stage?

That's my favorite at the moment

We don't know the name of this "big lady"...? A peek into its documentation might give some clue.

Her Name is TR14 and Abbey is right. This is a so called "Musiktruhe" in original condition. Still functional!(with loud hum and bad FM section.).I played guitar over it, yesterday. Pretty silent for 12 Watts.

Signal from the plate of the bottom EL84 goes through the 50pF to the electrostatic tweeter. The 100k resistor is there to provide the necessary DC bias. The capacitance of an electrostatic tweeter is a few 100pF, so it receives about 1/5th of the AC anode voltage.

Really, are you sure?

Thanks to all for your feedback.

 

[mad.ax]

I believe Abbey is right about the electrostatic tweeter
You can check that theory easily; Look at the speakers baffle from the inside, to what is connected the blue wire?

 

[rock soderstrom]

I believe Abbey is right about the electrostatic tweeter
You can check that theory easily; Look at the speakers baffle from the inside, to what is connected the blue wire?

I will check this after breakfast, this section is covered with some fabric from behind, as well. I will post a additional photo later.

 

[rock soderstrom]

I believe Abbey is right about the electrostatic tweeter

Yeah, Chandra & Abbey were right, it is a electrostatic speaker. You can see it in this photo in the right lower corner.

But there is no treble at all in the moment, sounds pretty boomy, I guess some caps need replacement.

Nice power transformer on the left. On the right you can see the PP OT.

PP power amps are quite rare in german vintage tube driven radios, reel to reel tape recorder and music cabinets. Most of time, they are only SE with under 5 Watts output power. This old Lady should give with some tailwind (aka new PSU caps) up to 12 Watts!

BTW: this is almost a wonder that this beautyful piece of gear is still working after 63 years! All components are original!

 

[abbey road d enfer]

. Still functional!(with loud hum and bad FM section.).

It's the typical syndrome of these beasts. Need recapping and retubing the radio section, particualarly the oscillator/mixer.

 

[abbey road d enfer]

But there is no treble at all in the moment, sounds pretty boomy,

Remember, German radio and HiFi of the time were very boomy. Oom pah pah forever!
Yours has a nice finish; is it mahogani?
I like it much more than the most common dark walnut.

PP power amps are quite rare in german vintage tube driven radios, reel to reel tape recorder and music cabinets. Most of time, they are only SE with under 5 Watts output power. This old Lady should give with some tailwind (aka new PSU caps) up to 12 Watts!

My parents had a beautiful Saba stereo unit that had one ECLL800 per channel, for 2x10W. (it was boomy too)
This thing disppeared when my parents left the house for the retirement home...
It was the machine that made me discover the Beatles, the Who, Wes Montgomery...

 

[abbey road d enfer]

BTW, how is that type of radio combo named in German?
It seems Röhrenradio is limited to table-top radios.

 

[Bo Deadly]

Remember, German radio and HiFi of the time were very boomy. Oom pah pah forever!

Sounds perfect for listening to hip-hop.

 

[abbey road d enfer]

Sounds perfect for listening to hip-hop.

I always had an inch that hip-hop owed a lot to oom pah pah.

 

[rock soderstrom]

Oom pah pah forever!

Ha ha, that's right! This particular sound is infamous.

Yours has a nice finish; is it mahogani?
I like it much more than the most common dark walnut.

I'm not entirely sure, but I think it's Elm, which was a paid upgrade to the standard version. I like it a lot, as it fits well with the rather light design, makes the whole thing not so visually heavy.

The wood still looks good, but the clear coat is very worn, especially on the top. But you could scrape off the varnish relatively easily and refinish it with Danish oil. That would look great!

My parents had a beautiful Saba stereo unit that had one ECLL800 per channel, for 2x10W. (it was boomy too)
This thing disppeared when my parents left the house for the retirement home...
It was the machine that made me discover the Beatles, the Who, Wes Montgomery...

Saba did some really good sounding radios!

BTW, how is that type of radio combo named in German?
It seems Röhrenradio is limited to table-top radios.

This kind of device class is actually called Musiktruhe (musik chest) and basically consists of a tube radio with speakers plus a record player. Other names are Tonmöbel (sound furniture) or even Musikschrank (music cabinet). But Musiktruhe is the most common name, although this term is known only to older people.
The furniture character is in the foreground in all designations. Often in this kind of furniture was also integrated a small minibar with plenty of spirits.

The Siemens TR14 and similar models are not well designed in terms of sound in my opinion.
The bottom-mounted speakers mainly affect the ankles, especially in terms of trebles.

I find this design superior, the sound is simply better due to the higher speakers. These were also available in stereo at the end of the tube era!



The real high-end devices had loudspeakers that could be positioned freely in the room.

 

[abbey road d enfer]

I'm not entirely sure, but I think it's Elm, which was a paid upgrade to the standard version. I like it a lot, as it fits well with the rather light design, makes the whole thing not so visually heavy.

I agree. Much better IMO than the typical dark brown /polyester finish.

This kind of device class is actually called Musiktruhe (musik chest) and basically consists of a tube radio with speakers plus a record player. Other names are Tonmöbel (sound furniture) or even Musikschrank (music cabinet). But Musiktruhe is the most common name, although this term is known only to older people.

Thanks. I'll use the term for my searches.

The Siemens TR14 and similar models are not well designed in terms of sound in my opinion.
The bottom-mounted speakers mainly affect the ankles, especially in terms of trebles.

I agree. OTOH it makes a great stand for a large flatscreen TV.

I find this design superior, the sound is simply better due to the higher speakers. These were also available in stereo at the end of the tube era!

View attachment 98201

Very nice!

The real high-end devices had loudspeakers that could be positioned freely in the room.

Well, the 1970's generation of such apparatus was much better technically (although the solid-state receiver section was a step back compared to the tube ones) but less attractive IMO.