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RFZ VK290 (80's German Mic Preamp) / Who knows this preamp? (Pictures) Channel Strips
Old 15th November 2014
  #1
Here for the gear
 

RFZ VK290 (80's German Mic Preamp) / Who knows this preamp? (Pictures)

Hi,

Who knows the RFZ VK290 Mic Preamp? I found some info here but it seems this mic preamp is very rare.

RFZ VK290 bei Vintage Audio Rentals in Hamburg


Pictures :

http://img11.hostingpics.net/pics/283575VK290front.jpg

http://img11.hostingpics.net/pics/271391photo27.jpg

Thanks
Old 15th November 2014
  #2
Gear Head
 

That almost looks like a West German amp. Black front panel, possibly same format as the danner modules. Cool unit! I haven't seen this one before. According to your link it is a later version of the 700-series. I have a V781 preamp. Very nice sounding unit.

Possibly recapped? Otherwise similiar build quality as earlier RFZ stuff. Should be good quality. You are possibly missing the output transformer. Would have been located in the consoles' main frame. Do not run long wire runs after this preamp.
Some of this stuff use negative rail power supplies, -24 volts.
Old 15th November 2014
  #3
Here for the gear
 

Quote:
Originally Posted by alhe View Post
That almost looks like a West German amp. Black front panel, possibly same format as the danner modules. Cool unit! I haven't seen this one before. According to your link it is a later version of the 700-series. I have a V781 preamp. Very nice sounding unit.

Possibly recapped? Otherwise similiar build quality as earlier RFZ stuff. Should be good quality. You are possibly missing the output transformer. Would have been located in the consoles' main frame. Do not run long wire runs after this preamp.
Some of this stuff use bipolar power supplies, +/- 24 volts.
Thanks,

I have reccaped the preamp with Panasonic FM caps.
In the pdf doc I have it's written :

ausgang elektronisch erdsymmetrisch

translation

output electronically balanced to ground

The VK290 works with +/- 15 Volts.

There's 4 x MAA748 opamps , I want to upgrade those opamps with modern ones like BB OPA134 or LT1537.

Is there something I need to know about those old MAA748 single opamps?

See pictures
http://img11.hostingpics.net/pics/99...uitMAAtags.jpg

http://img11.hostingpics.net/pics/91...COMPCAPTAG.jpg
Old 15th November 2014
  #4
Gear Head
 

Alright, I did not see the opamps. Browsing on my htc, so kind of hard to see your picture. Those metal cans are of course opamps. RFZ went to opamps in the 80s, probably for costs saving. Disregard what I wrote in my first entry. The unit will be symmetrical (balanced) from the input transformer to output. I don't know how good this circuit is. The earlier stuff is discreet, but use the same kind of input transformer. My guess is that it would sound okay, might even sound good.

It would certainly be interesting to hear the unit with upgraded opamps. It would probably be a fairly clean sounding circuit, with some added transformer color.
Old 15th November 2014
  #5
Gear Head
 

Somone else will have to fill in on opamp replacements.
Old 15th November 2014
  #6
Here for the gear
 

I have compared the VK290 to my Avalon VT 737SP.

The VK sounds fat compared to the 737. More low frequency and less top end but high frequency are very smooth.
To my ear too much low frequency with the low pass filter on Linear (inactive) position. It sounds best (on my voice) with low pass filter on 140Hz position.

The VK290 sound is typical, never heard this sound signature before , very pleasant.
To my ear this mic pre compete the 737 easily. I won't tell it beats the 737 because it's different sounding but it's on the same level.

I hope an opamp upgrade will open a little the top end.
Old 24th November 2014
  #7
mixmixmix
Guest
Why do you want to upgrade? Those Rfz designs are awesome. You may make it sound worse. In any case I would recommend recording few sources before and after the upgrade and then comparing to see whether you like the upgrade. Good luck
Old 5th January 2015
  #8
Here for the gear
Hi friends,

the VK 290 is a preamp made by VEB Deutsche Schallplatten- This was a company in the former GDR . They made this preamp for recordings at the different labels in the former GDR (ETERNA, AMIGA and so on).

This preamp wasn´t developed and build by the RFZ (Rundfunk- und Fernsehtechnisches Zentralamt).

They use this preamp in the Regieeinrichtung 82.

I think This preamp ist better then V781, MV 810 and so on.

In my opinion it isn´t a good idea to change the MAA 748, because they work in different filters.

Best regards and a happy new year.

jokeramik
Old 28th December 2017
  #9
Here for the gear
VK 290

Hi,

what are you doing with your VK 290?

Best regards!

jokeramik
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