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MBM

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About MBM

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  • Location
    Germany Munich
  • Interested in Sound for Picture
    Yes
  • About
    Started my Career in early 80s as a developer of amplifiers and tape Recorder for Studios. Later one went into the Computer Business but had my customers always in the Broadcast / Film and Post production.
  1. #635 Constantin, Hi Constantin, you are right, my statement "ARD-group as goverment owned" was not correct translated. What I meant was the the ARD is not a group of private broadcasters, but paid by the germain goverment tax (GEZ). (To be independent of private business limits) As you are in located in cologne I guess you are working for a company that is related to media/ broadcast. Let me know which one. Because my customer at cologne were RTL, CBC, Qvest,but not WDR. I am still searching for an NAGRA IS. MBM
  2. old mixer from an old mixer

    Hi Sprotnik, Just walked in this thread and saw that you have questions about a STELLAVOX AMI48 mixer. If you are still interested, I guess I can help you. I own the mixer and the reel to reel recorder SP8 and had to repair everything by myself. Believe me, the maschines look good outside, but inside its a mess and a nightmare. The current Stellavox people are completly arrogant and not helpful. Instead of being happy that people out there who still keep this things running, they want to hide informmation and try to squezze out money as much as possible for everything. For this reason I have re-drawed a couple of this modules from the mixer and tape recorder. The module for the mic-amplifier in the mixer is called SPA+SOA. SPA+SOA stands for StellavoxPreAmplifier + StellavoxOutputAmplifier I had opened the defect module and re-draw the schematics in it, including pictures and all components. So if you interested, I can post it to you. MBM
  3. NAGRA IV-SJ Has anybody tried to record on this maschine 0Hz - 200Hz (or 4kHz) ? Most people do not know it, but it seems that you can do that on track 3. Track 3 (middle between upper and lower track) is normally the pilot and clapper track. When you look very close in the schematics of this track 3 you can find out the following: It seems an Input signal at the CUE connector (Pin 1) can be recorded in two different ways: Way one: I call it "normal" way. If you connect a microphone (or low level source) at the connector "CUE", located at the right side of the NAGRA the signal will recorded in a normal way. (250Hz - approx. 15kHz) (Frequencies below 250Hz will be cutoff, because you need the lower 50/ 60Hz for the pilot signal itself. With that clever idea you can record the pilot signal 50 or 60Hz AND a speach at the same track. Now coming to the funny thing to record 0Hz (DC) to 200Hz (or 4kHz) Way two: If you bridge Pin 2 and Pin 5 on the CUE connecter, you switch ON an FM-modulator inside the recorder. The FM-modulator has a frequency of 13,5kHz (or 17kHz), depending how you set this carrier frequency. Now with a microphone (or low level source) connected to Pin 1 as before the signal will NOT recorded directly but this signal will modulate the FM-modulator and that signal will be recorded. (That means if your input signal is 0Hz (DC) you record a frequence of 13,5kHz. (If your input signal is i.e. 200Hz the recorded frequence is 13,5khz + 200Hz = 13,7kHz. (Maybe someone can guess, why i wrote the (or 4k) too. Say if you set the FM-modulator frequency to 17kHz and add the 4kHz you come by calculation to a recording frequency of 21kHz. And I guess that is the absolute maximum you can record on this track 3 head. Hope this information is interesting. MBM
  4. Hi Mark, Thanks for the kind words. I also have an AMI48 mixer. As they had a couple of problems I was forced to repair it. But without schematics that's really hard. So I re-draw the two major modules in the mixer by myself. This are the module labelled: SPA-SOA (mean: StellavoxPreAmplifier - StellavoxOutputAmplifier) SPA-SEM (mean StellavoxPreAmplifier - StellavoxEqualizerModule) For your convenient you can find below in the attachment a picture of an open AMI 48 mixer and two PDFs with my drawings and measurement information for the modules, including everything a technician needs to fix them. SPA-SEM Module Diagram.pdf SPA-SOA Module Diagram-ver3.pdf
  5. Hi JBond, I can not tell the exact date, but if you find NAGRAs with the plate CR#11 and SWF, the unit must be older than 1998. Reason for that is that in year 1998 SWF (SüdWestFunk) joined with other broadcast company SDR (SüdDeutscherRundfunk) to the name SWR (SüdWestRundfunk). The usage of the NAGARs were "field recording" for interviews and documentary films for TV. The NAGRAs were the main recorders and was found in any broadcast company here in Germany. The competitor "STELLAVOX" tried hard to step into that market too, but the only Stellavox SP7 / SP8 I saw was at goverment owned broadcaster SR (Saarländischer Rundfunk). The Stellavox was a little bit smaller, like the NAGRAS IS, but had a lot of disadvantages, from the point of servicability and adjustments. As I stated in the previous post, all goverment broadcaster are members of ARD group. And for that reason they had to exchange the "material (audio recordings) at that days physically between the station without hassle. To do that they had a "common" requirements about audio-level, equalization, coloring of the for-tape, tape-source, etc. That was the reason why EVERY NAGRA (or other units) had to adjust to that specifications. (Stellavox had problems to meet that criteria, because i.e. equalisation was pre-soldered in the head unit. If you want to changed that you had to send the unit back to the factory and they did the job. Not really convinient, if you run 100s of recorders in the field.) I know this, because SR (Saarländischer Rundfunk) was a customer of mine when I worked for Silicon Graphics. Finishing after 6 years the project at SR I got as a gift from them the "last" used Stellavox SP7. (To bring the Stellavox back to real life (common equalisation, level) was another story.) If I have time I will make a couple of pictures from my NAGRAs and Stellavoxs in the next days. Maybe its expanding this thread to much, but Stellavox was always very strict with schematics about their units. They never distributed that stuff in total and most of the PCBs were sealed in resin. If sombody has a problem finding schematics he can contact me, because I have "re-draw" a couple (not all) of the PCBs. Another information about the NAGRA SN: This units were used at BR (BayerischerRundfunk) as field recorders for documentary films for TV too. Specifically as the NAGRA 4 was to heavy. I know that because BR is also a customer of mine, and a couple of years ago I bought the SN-Reels from them. And surprisely they forgot to erase one of the tapes, so I heared the audio-shot about a documenary of flowers in the mountain. BR also used the LPS-unit to transfer the pilot tone to the NAGRAs they used in the post-production.
  6. Maybe I can clarify a little bit the NAGAR 4.2 IRT. The name IRT is the short name of "Institut für Rundfunk Technologie" This company is owned by ALL German goverment Broadcast companies. In germany the goverment owned Broadcaster are members of ARD. (ARD means group of broadcaster.) This ARD members own IRT. IRT is the research & development company for them. (i.e. they developed MPEG Layer2 Audio) IRT is a customer of mine and I have weekly talkes with them. The NAGRA mentioned in the article #556 was changed to the specification of IRT by Nagra. (It was used in the research department of IRT in Munich/ Germany) Another clarification about one topic about NAGRA with a plate CR#11 and SWF. In Germany every equipment that goes (and used) by goverment owned Broadcaster, has to pass the RFI-Tests. (RFI means Radio Frequency Interference), to make shure the equipment will work properly without disturbe any other equipment by "HIGH Frequencies". So what you saw on that plate were two things: CR#11 = test for RFI SWF = is the shortname of the broadcaster SüdWestFunk, the old name of the goverment owned broadcaster located in the west of germany. (Stuttgart). The name is changed to SWR many years now. As Nagra wantet to do business with ALL this broadcasters in the ARD-group in Germany they had to align their NAGRAs to the specific requirements. For this reason you will find other NAGRAs (mainly series IV) with plates showing: SWF = SüdwestFunk NDR = NordDeutscherRundfunk WDR = WestDeutscherRundfunk SR = SaarländischerRundfunk and so on. NAGRA also manufactured a bunch of NAGRA III specifically for TELEFUNKEN. (Telefunken was the main source for all goverment owned broadcaster in Germany. Mike Bormann-Mayer
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