Telefunken V620 wiring

[Johnny1234]

Hi all,
I am in the process of wiring up a pair of Tele V620 mic pre modules.
The module has a neat little fader mounted on it....pin 7,6 earth....pin 16 wiper....pin 10,11 top.
I am using an 1:10 input transformer no problem. I am also using a 1:1 output transformer.
Looking at the connector diagrams last page of schematics seems it is only used for no output
transformer mode. Just wondering if I can jumper the fader in via pin 6. Is TR5 capable of
driving the 1:1 output transformer? Should be easier except I do not speaker of read German.
Any and all advice greatly appreciated.
Maybe time for some Babble lessons online.

Many Thanks
Johnny1234

 

[nsalis]

I assume that you have a V620 module without an additional designation (i.e. no V620a, b, c, d).

The V620a has three unbalanced outputs:

Output 1 (pin 6 of the connector) is the main output. Its nominal level is 100 mV (-18 dBu), the output impedance is 20 ohms. Maximum undistorted output level is 3.1 V (12 dBu). That means the device has a headroom of (12 + 18 =) 30 dB. The load impedance must be higher than 200 ohms.

Output 3 (pin 15 of the connector) is the prefader listen output. Its nominal level is 100 mV (-18 dBu), the output impedance is 500 ohms. Maximum undistorted output level is 3.1 V (12 dBu). That means the device has a headroom of (12 + 18 =) 30 dB. The load impedance must be higher than 5000 ohms.

Output 2 (pin 8 of the connector) is a so-called current output. It is only suitable for the zero-ohm input of a summing amplifier and cannot be used for your purposes.

In order for the output amplifier T5 (SG2183gn) to get a signal, it is necessary that pin 15 is connected to pin 11.

If you want to connect an output transformer to the after-fader signal, connect its primary winding to pins 6 and 7.

But the question is: Why do you want to connect an output transformer? Whether this is justified or not can only be answered if you know which destinations are fed from the V620.
In general, I would only install output transformers in those cases where you do not know whether the destination has a balanced or an unbalanced input.

Generally, it is much wiser to forego the output transformer and instead install an input transformer on the following device.

Inserting an input transformer in front of the unbalanced or electronically-balanced input of a device results in common-mode rejection of more than 100 dB, i.e. high immunity to common-mode interference (dimmers, etc.), regardless of whether the source is balanced or unbalanced.

A suitable input transformer is the Jensen Pi-2XX

https://www.jensen-transformers.com/product/pi-2xx/
As mentioned above, the nominal ("0 VU") output level is only 100 mV (-18 dBu). This means that the device can feed a consumer hi-fi device with an RCA input directly, but not a professional device that expects a nominal level of 4 dBu (1230 mV).

The Telefunken module system was designed in such a way that several input modules V620 were connected in parallel via pin 8 and fed to the zero-ohm input of the summing amplifier V621. The V621 amplifies the mixed signal and produces a nominal output level of 6 dBu (1550 mV).

Nick Salis