Interesting Siemens monoblocks I happened upon...

[Svendingo]

I guess I'm throwing this out there to see if anyone knows anything about these amps I picked up.

They appear to be Siemens A401 power amplifiers from the 80's. I suspect they are meant for studio or radiostation use. I was told they were 120wpc. The page I found at radiomuseum.org seems to support that. These are little tanks, and that beefy toroid is crammed inside each one.

They have 5pin din inputs. I'm mystified by the 24v battery input, unless it's a backup ps option. Would I need a battery, or other 24v supply in addition to mains power? There is a 24v led pilot on the face, as well as a clef (input signal perhaps), and some other odd symbol with an led.

The 31v/8ohm jack confuses me, but what do I know?

Does anyone have any info on these, specs, etc?

Here are a few pics, and link to the radiomuseum page.
http://www.radiomuseum.org/r/siemens...verstaerk.html





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[Svendingo]

I'm a bit dense. After looking at the amps further, I noticed the other holes on the front panel are trim pots. So we have a 24v light, clipping light, output meter, volume pot at the bottom, and two others... it shows clearly in the pics.

[Tekko]

2 transformers, looks like it has a line output transformer as well for not only a 8 ohm speaker but also a 31, 70 and 100V line output.

These are likely PA distribution amplifiers.

[Wavebourn]

Nice donor for stereo class A hybrid room heater!

[jacco vermeulen]

Search for Variodyn 2000

[megajocke]

Originally Posted by Svendingo

I'm a bit dense. After looking at the amps further, I noticed the other holes on the front panel are trim pots. So we have a 24v light, clipping light, output meter, volume pot at the bottom, and two others... it shows clearly in the pics.

The two different clefs are often used to indicate tone controls. One is treble (G-clef, the curly one) and the other is bass (F-clef).

Clef - Wikipedia, the free encyclopedia

[Svendingo]

Originally Posted by Tekko

2 transformers, looks like it has a line output transformer as well for not only a 8 ohm speaker but also a 31, 70 and 100V line output.

These are likely PA distribution amplifiers.

Tekko,
I've begun to believe that also after a Google translation of the Radiomuseum page:

"Siemens 120 W power amplifier A401, item number 98 392-A9701-A401-1;
For sound reinforcement, 31 V / 8 ohms, DIN connectors, IC amplifier with high-performance toroidal transformer power supply, mono, sound and volume control on the front, LED signal level meter"

Any ideas on how much fiddling it would take to make these "home hifi" usable? I'm at a bit of a loss with pro-sound type equipment.

What is the chance these have low distortion and bandwidth, as-is? 120w is higher power than most of the other distributed line stuff I've come across.

[Svendingo]

Originally Posted by jacco vermeulen

Search for Variodyn 2000

I looked that up, and it was released a few years later, and I can find little real specifications. It looks like that was a type of networked line level system with modular components, pretty forward thinking stuff then.

Do you know if that system used these amplifiers? I can't find any connection in my searches.


Thanks for the responses guys!

[jacco vermeulen]

Siemens Variodyn modulare Verstärkerzentrale

The series also included a model with more power, could be a later addition.
Siemens still uses the Variodyn name for their current range.

[jez]

With that 100V line transformer and 24V power options it looks to me like a "voice alarm" amplifier to me. Used for announcements and pre-recorded messages in the event of fire, hence the need for battery back up. I have several similar amps made by French company Bouyer which are mainly being used as transformer doners as attempts to sell them on e bay have resulted in zero interest!