Strange Module: "Telefunken" Neumann preamp

[mmadu]

Recently, I found a strange preamplifier at a local dealer, which seems to be a Telefunken brand, but is internally marked as Neumann, and has the iconic OV10 operational amplifier. It contains three signal transformers. Does anyone know what this module is? How can it be used?

 

[k brown]

I would guess,, like the U47, this is a Neumann unit marketed in the US under the Telefunken mark.

 

[mmadu]

I would guess,, like the U47, this is a Neumann unit marketed in the US under the Telefunken mark.

After a period of searching, I have some guesses about this module. According to the speculation, it is similar to the PV46 or OV60 (OV-OMV, haha!) produced by Neumann - they have the same input transformer (Haufe RK204), the same operational amplifier (OA10). But for the output transformer RÜP 114M, I did not find any information, I have sent an email to the documentation staff of pikatron, and look forward to the reply. Well, to sum up - this is a microphone amplifier module produced in 1930, maybe it changed its name (according to k brown) for selling in the United States. If anyone can provide further information, I will be very grateful.

 

[k brown]

Hmm - looks more like something from the 60s, rather than the 30s.

 

[Brian Roth]

Back in semi-ancient history, a company called Gotham Audio had managed to "control" the import of Neumann products into the USA. Look up Gotham or it's ....mmmm.... to be polite... it's very cranky owner, Stephen Temmer.

Perhaps the reason for the dual markings?

Bri

 

[mmadu]

Hmm - looks more like something from the 60s, rather than the 30s.

Oh, I think you are right, I just saw the word “930” on the label, so I had this guess.

 

[mmadu]

Back in semi-ancient history, a company called Gotham Audio had managed to "control" the import of Neumann products into the USA. Look up Gotham or it's ....mmmm.... to be polite... it's very cranky owner, Stephen Temmer.

Perhaps the reason for the dual markings?

Bri

Ah, I think I understand. That was a confusing history. Speaking of which, I did not find a completely similar product, maybe it is customized or produced in small quantities? I don’t know.

 

[rock soderstrom]

Hmm - looks more like something from the 60s, rather than the 30s.

rather 70ies

 

[Khron]

Looks like there are spots for four output transformers, but no (external) gain adjustment - some sort of line / distribution amp?

 

[rock soderstrom]

Looks like there are spots for four output transformers, but no (external) gain adjustment - some sort of line / ditribution amp?

Most likely, although the gain could also be controlled externally via the contact pins

 

[abbey road d enfer]

Well, to sum up - this is a microphone amplifier module

I'd rather think it's a 1 into 4 distribution amplifier. One can clearly see there are 4 different outputs (although two xfmrs have been cannibalized).
I don't see a gain control, so it may be a unity-gain thing.
Be ready to replace all these orange caps.
I think you should trace the circuit, it's not too difficult since it's a single-layer PCB.

 

[rock soderstrom]

(although two xfmrs have been cannibalized).

Not necessarily cannibalised, it often happened that these cards were not fully loaded from the beginning because this option was not needed. Edit: In this case, however, two OTs were clearly unsoldered.

I think you should trace the circuit, it's not too difficult since it's a single-layer PCB.

+1

Be ready to replace all these orange caps.

+1

 

[Brian Roth]

Looking at the pix again, I also vote for a distribution amp; PCB traces from the two existing and two missing xfmrs heading to the connector.

Distro amps were once very common in broadcast applications, and are often unknown to folks besides us graybeards. <G!>

 

[Brian Roth]

Not necessarily cannibalised, it often happened that these cards were not fully loaded from the beginning because this option was not needed.

+1

+1

It sure looks like SOMEONE did some poor quality butchery at those two positions on the card.

Bri

 

[rock soderstrom]

It sure looks like SOMEONE did some poor quality butchery at those two positions on the card.

Bri

You're right, I overlooked that. But as I said, many were simply not fully equipped. In this case, however, they were clearly canibalised.

 

[Brian Roth]

You're right, I overlooked that. But as I said, many were simply not fully equipped. In this case, however, they were clearly canibalised.

I understand "partially loaded" options! <g> Eons ago I did design and installs of analog broadcast TV systems and often "short loaded" cards would be shipped from the manufacturer as part of a project.

Bri

 

[rock soderstrom]

The two ERO tantals 47/20V at the input transformer do not seem to be original, as they were installed somewhat sloppily. They were added later, the traces on the undersite were changed afterwards in this position..

 

[k brown]

Ol' 'Eagle-eye Soderstrom'!

 

[mmadu]

Thank you for everyone help! I totally agree with Khron's guess that maybe the RK204, which is often used for the mic input transformer, was misleading, now I guess it may be the reverse link - for the line input.

Pikatron's technicians still haven't responded, and it looks like some employees are on furlough. But I have reason to guess that these RUP transformers are 1:1 signal transformers.

I dug through some old posts and it looks like the Neumann O__ series is really hard to find. So probably not because of US sales (other than the Telefunken trademark).

I've decided to buy it and see what I can do with a 24v supply.

 

[mmadu]

Oh, according to @rock soderstrom's observation, the capacitor is 20v, maybe it needs 15v power supply? I do not understand.