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    I have been working with film post production for 12 years; I am now primarily working with TV (on a danish national broadcaster, as well as being involved i film projects. I am quite fascinated by Nagra recorders and everything connected with them.
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  1. Or talk to Mike Harris (mikesfilmsound.com); he can help you with spares and/or do the actual repair. As you write the belt size is not critical, but it will have to be completely smooth, or it will be very noisy when the Nagra is winding.
  2. It is the (ex-)rubber coating on the tacho disc, where the winding idler makes contact. I have one that had the same problem... You can buy belt sets for Nagra III, and in that set there are three belts: Two belts for the reels, and one that can be fitted on the tacho disc wheel. Here is an example: https://www.ebay.com/itm/284563609320 If the reel belts are the grey neoprene type, I wouldn't replace them; they rarely fail. It is not exactly easy to replace the belt/rubber coating; to do it you have to remove the motor and the motor chassis. The worst part is the removing of the motor from the capstan/tacho shaft. On the gearspace forum (reel-to-reel part) there is a description on how to change the bearing on a 4.2; you don't have to disassemble the motor, but it is described how to take out the screw holding the shaft. Be certain to pay attention to every single part; if you do that and you have some sense of mechanics, you can do it in an hour or two (or faster, but that is not advisable).
  3. I would guess that one of the largest "disruptions" in sound work was the introduction of portable location recorders (especially the Nagra III in the early 60´ies). Before that it took a sound team and very heavy machinery to record any kind of location sound. After the advent of portable recorders it became possible to work with 1) hand held cameras, which came at that time, and 2) a much smaller sound crew, perhaps even just 1 person. The next big shift came with the flash/hard drive recorders (and better wireless microphones), which made it possible to easily record more tracks/microphones. So the portable recorders made hand held recordings possible, and the multiple tracks made it possible to be even more flexible, once the boom mic wasn't´t (about) the only source when out recording. My background is in danish film post production (now TV), and one of the things that we saw with the advent of multiple track recorders was that more work was given to the people doing the recording. Before that their main task was making the recording and handing in the tapes. Since there was just 1 or 2 tracks available, all attention could be given to record these 1 or 2 tracks optimally. With the new recorders, not only did it take more time to mic the actors up, but since the editing department was pressed for time (the budgets, again...), the recordist now also had to make a temp mix on site, so that he/she could deliver a 2 track mix for editing. That was quite stressful for some, and I remember several occasions where the recordist had to redo the 2 track mix for delivering it to replace the first mix in the editing department on a daily basis. In some ways it was like the proverbial washing machine: When you get the washing machine it makes it faster to wash, but that just means that you are washing more...
  4. I know that it not exactly the area that you are working in, but there might be some inspiration in this paper from 2020 about the changing role of sound engineers/technicians in the BBC: https://pure.royalholloway.ac.uk/portal/files/33017740/2018heathtphd.pdf It is aimed at describing the changes for TV sound people (in broad terms) more than Film production, but I guess that some conclusions will be the same. And in any case, it might be an inspiration, or you can checke sources of the paper... I have been working in film post production (currently I am working with broadcast technologi), and I would say that one of the most important technological changes for the last generation has been moving from tape based recording to file based systems. Not only did the new(ish) digital recorders allow faster turnover, but they also made it possible to record ever more simultaneous tracks. And transfer the material to the editing department much faster, so that editing could start almost immediately after the recording had ended. One thing to notice, is that the changing roles and working conditions for sound production has also been influenced (a lot) by ever increasing workload and ever smaller budgets...
  5. When we used Sennheiser MKE1 at my work, we always had problems with damaged insulation, and that was solved with rubber grommets, glued at the damaged spot. Just a drop of glue is sufficient, the capillary effect will make sure that the glue is distributed evenly. On the MKE1 the grommets are already there (for protecting the cable at the mic clip), but the grommets can be bought separately. To put on the grommet, you will need a three-pronged (normally) tool, but that is not expensive, at might come in handy with other cable repairs. https://eshop.wuerth-industrie.com/Produktkategorier/Rubber-grommet-polychloroprene/15435505060201.cyid/1543.cgid/da/DK/EUR/ https://www.hellermanntyton.com/dk/produkter/vaerktoj-til-tyller/na1k-3/621-10103 The grommets can probably be sourced easily from other suppliers.
  6. Just a note about the manuals warning about leaving the tape control lever in the Open position for long durations: It sounds a bit cryptic, but the O-ring that the text refers to, is an internal rubber ring on the capstan/tacho disc. When the lever is in "Open" a metal wheel is in contact with the idler wheel (the disc with a rubber ring as outer surface), and that may make a dent in this O-ring. This dent will make winding a very noisy and bumpy affair, since the idler wheel rotates quite fast, so that is to be avoided... But the moment you go into Stop-mode with the function switch, it is safe to put the machine aside for any amount of time.
  7. Your machine seems well kept, but I am wondering about the black belt on the take up reel; I would guess that it would have been replaced together with supply reel belt (which is the newer neoprene type). The black rubber belts have a tendency to get a bit loose, where the neoprene belts rarely fails. But it I is not loose, it is completely fine. It seems to be manufactured as a pilot enabled recorder, but the pilot boards have been taken out. Now I think about it, I have never seen a non-pilot 4.2, so it might be that they always put in the head, even if it wasn't pilot enabled. But again it is quite rare that you would need the pilot option, unless you record sound for film/video, where lip sync is all important. With these preamps and without the phantom supply, there is no easy way to use 48V microphones directly on the recorder inputs, but with a simple (and cheap) phantom injector it will probably work. How the microphones will respond to the input impedance of the input (meant for dynamic microphones) is another matter. I guess you will have to try it... Regarding the tape type, I can see now that it is biased for BASF 468. Unfortunately I am not well versed in current tape types, so I can't help you on more current options...
  8. Congratulations with your 4.2; it is pretty nice, and it seems well kept. It is an early version, which is why you don't have the later upgrades/additions (head shield, tape counter, identical knobs, ruby tape guides). It is also without the ALC (automatic level control) circuit, but that is almost never used anyway. If you look for a new lid, be aware that the early models used a rotary latch, while the later models had a dual push lock. Lids are not interchangeable between the two types of locks. Regarding your questions: 1) The recommended tape type depends on what it it is calibrated for. I can't remember the tape type, but I think that the manual states what tape type it is biased for. I will check... You can use old tape, but beware of SSS (sticky shed syndrome); it is not harmful to the Nagra, but you will inevitably have very bad results. And you will have to clean the tape path constantly. 2) You can leave the machine with the tape on, as long as you make sure that it is in "Stop" position. I that position the pinch roller is lifted a bit from the capstan, so there will be no harm in leaving the tape on as long as you want. 3) The power supply you have is perfectly fine; it is an old Apple Powerbook supply, and its 24V is a good compromise between good winding speed but no arcing on the function switch. If the Nagra runs with the power supply it is correctly polarized. 4) The main differences between the older and newer models, apart from the cosmetic things, are the later (or optional) ruby tape guides and the head shields. Both are nice to have: The ruby guides are far more durable than the older all-metal guides. Apart from that, all 4.2 units are just about identical, regardless of age, 5) Apart from missing the lid it seems to be in good shape. I can't make out the pinch roller colour; if it is brown it is the neoprene type, which is very, very durable. If it is black, it is made of rubber, and they can sometimes get hard and brittle. But if it is OK now, it will probably stay OK. One of the things to look out for is the motor; it should run smoothly and quietly; it shouldn't "knock" or rumble. If it does that, it will probably need a new motor bearing. Theoretically the drive belts could also be worn, but normally the 4.2 has neoprene belts, and they rarely need to be replaced. You should open it up and enjoy the look of the interior. To open it, you just loosen the two large screws in the speaker end (just loosen it, don't unscrew it completely. when that is done, you can open it up and enjoy.
  9. And I know where one of the other MX´s are... Fortunately I am sure that all the test users knew that it was well worth keeping it, so they are probably out there still... I am not sure when it was released, but I guess that it was about 2006-2008 (the EMP came in 2011). But the design is a bit similar to the Stelladat, which was a bit earlier, but with the same top plate with controls, covered by a lid.
  10. Only 10 Nagra MX mixers were made, and they were apparently made as evaluation samples. It was a small 4 channel (2 Mic + 2 line) mixer, and it was made to the same quality standards as all other Kudelski products. The problem was that it was a bit hard to figure out what to use it for: It was a 4 ch. mixer but only 2 mic. inputs, making it effectively a 2 ch. mixer, since you hade very few line sources on a set. If you should have line sources, they couldn't be controlled from the front, since there was only two controls, controlling the mic. input gain. All other settings and adjustments were made on the top side of the mixer, under a plastic lid. That made it a 2 ch. mixer, completely unusable for bag use and thus it didn't have any real world use (since it was too limited for using on a cart). At the time it was released people were beginning to require more channels, and for quite some years SQN had made very good and practicals multi channel mixers for bag use. So the MX was floundering in the middle of a no mans land... As a kind of gimmick, it could record, but only in 16 bit/48 KHz, making it only suitable for preview files, not as a primary recorder. Fortunately they quickly found out that it was a fundamentally flawed product. and cancelled it. A bit later they launched the EMP, which was more focussed on being a high quality mic preamp, and it was quite practical if you had a Nagra IV and wanted two more mic. inputs... So the MX is a great little mixer if you needed a quite special feature set, but for universal use, there were better and much cheaper solutions...
  11. I know the feeling; apart from that I got mine for a very reasonable price, I had the same problem. The SP7 electronic design is actually quite simple, and there are ways of quickly locating the problem, but it require som knowledge about electronics. If you want it, I can try to help you along, but if you are not familiar with electronics, I would advise you to find a person to help you. He/she doesn´t need to be an expert, but it would be very helpful, if I could make suggestions for measurements and you (or your helper) can answer back about the results... First a comment about the belt: The steel belt is a crap idea. It is noisy, and I have replaced it with a Nagra belt, which actually fits nicely. I also bought a "replacement belt" on eBay (from USA), which was way too inflexible, and the motor had to struggle quite hard. So the Nagra belt stayed in. When you say that it won´t turn on, does it mean that it is completely dead, or is it "just" that the motor isn´t running? This is important to know, since the supply voltage is regulated in the SVS module, so if everything is dead, the problem is around that module. If the electronics are working, but the motor is not running, it could be the SMU module, which have a tendency to get defective. You can send me a message (or an email) about your findings, because it might not be interesting for others to read about Stellavox problems in a Nagra thread...
  12. Once in a while Stellavox is mentioned as a rival to the Nagra, and I still remember browsing through "HiFi Revyen", a danish HiFi yearbook listing all the available/distributed products and dreaming of one day getting a Stellavox... Since then a lot has happened, but in this context the most important probably was that I became interested in Nagras in stead, and Stellavox took a second seat. But still the comparisons between the two brands made me curious, and late last year I got tempted by a Stellavox SP7 in a dubious state, but for a good price, and I couldn't´t resist it. If nothing else, it would give me the opportunity to finally see what all the fuzz (and the odd harsh comment) was about... I got the SP7 in a terrible state; it had been stored for a long time, so all bolts were corroded, the cover was scratched and it sounded like an angry lawn mower when/if it ran. It soon transpired that there was a lot of faults, and some not just cosmetic. After getting rid of the steel spring belt (replacing it with a Nagra belt), lubricating, cleaning, sanding and polishing, I ended up with a functioning recorder. I thought. Then the motor started cutting out intermittently, and after some experimenting I realized that the SMU motor control module was defective. In a sane world I could take out the module, fix it and put it back in, but in the early SP7 units all modules were filled with resin, making it impossible to fix it. And that gave me the first two lessons: 1) If a module fails, you will have to buy another one. You can't fix it without risking to destroy it. 2) Dont expect any documentation is at hand, since Stellavox were quite secretive and kept all documentation to a minimum. After buying a NOS SMU in Canada, I returned to it, only to find out that the motor still stopped intermittently, but this time the entire power supply set out. And again: Look at the SVS module, despair and order a new module, again from Canada. This time I felt sure that I was on the right track, because I made a replacement supply (perhaps better...) and put it in for testing, and it worked fine. Once I got it working, I got (over)confident and bought a stereo headblock. I installed it, and the result was total silence, just with a low crackling. I had been warned by a Stellavox connoisseur that SP8 heads might not be compatible with the SP7, and he was right. Fortunately I could return the heads and get another SP7 headblock. That worked fine, and then I knew: 3) Don´t assume that two Stellavox component are compatible, just because they fit the same connector. Then, at last, I could make a recording test. It sounded pretty good, but I was wondering about a low hum, which was a bit strange, since the casing is very well shielded and it was running on batteries. It turned out that the in built crystal generator was generating a 50 Hz sine signal, that somehow bled into the recorded signal. When I got rid of the generator, the hum disappeared. And returning to the motor control: I noticed that the speed was perfect at 7.5 ips, slightly unstable at 15 ips and unusable (and still about 15-17 ips) at 30 ips setting. I wondered what was wrong, and I was a bit confused when I measured the motor voltage at different speeds: With a set of almost new batteries, the supply voltage gave almost no headroom for regulating the motor speed at the higher speeds. I remembered that one of the big updates on the SP8 was higher supply voltage (15 AA batteries in stead of 12), and I can understand why: The SP7 is just about useless for running above 7.5 ips on batteries. On an external 20V supply it runs perfectly. Thus the next lesson: 4) Don´t assume that there the design is perfect, because it isn't. I am now at a point where I can say that it is getting there, but still I have the feeling that the SP7 more or less is a first version of the SP8. And I have given up upon making the right reel clutch completely silent, since it will involve rerubbering two small grooves deep inside the brake mechanism). So, basically (and I was warned about that from my Stellavox connoisseur friend): 5) Stellavoxes don´t like to be stored for longer periods. They age very poorly, and often quite a few bearings has to be replaced. But am I sorry that I bought the Stellavox? Not for a minute. I have the luxury of not being dependent on it functioning, but it has been really interesting and, believe it or not, entertaining to coax it back to life. It sounds really good, and despite its many quirks, it is a very well built device. One problem that is obvious when working with it, is that Stellavox was a much smaller company than Kudelski, which actually in itself was a small(ish) company compared to most other companies in the field. That meant that Kudelski had larger manufacturing capabilities, and the Stellavox feels more like a piece of hand crafted equipment that the Nagra. For better or worse; some of the weaknesses of the Stellavox are caused by these shortcomings, and the design itself is more idiosyncratic and less thoroughly done than on the Nagras. And it is absolutely horrible to service any component that is not built into a module; it is like they wanted to hide and stuff away the components in confined spaces just for the fun of it. One thing that really stand out is the motor, which is a little marvel: Designed and manufactured completely in-house, and almost flat. The rotor system weighs just 43 g, and it is controlled by a photografically applied tacho pattern. Not as powerful as the Nagra motor, but essential for making it possible to make such a small stereo recorder. On the down side, the Nagra is better at controlling the speed when the recorder is moved around in the rotating plane. But still better than most other manufacturers at that time (or, indeed, later). Operating the SP7 is basically like using a Nagra; there is not much difference there, and it feels every bit as stable as a Nagra. They came upon with a really neat solution for engaging the pinch roller and the stabilizer roller; they are engaged by a small, sophisticated gear system. Which unfortunately won't survive an attempt to operate it manually (thus the printed warning on the top of the SP8), and it also means that when going out of Play mode, the roller will still be engaged, and you have to make a brief Rewind to disengage it before leaving it. Weird, but understandable in some way. The Stellavoxes has a reputation for being more fragile and quirky than the Nagras, and I must admit that I can se why: The unrepairable modules, that were seated in connectors that were not really optimal for the task, the complete lack of documentation and spare parts, making it necessary to send defective units to Stellavox, the sometimes fragile drive system, the (missing) headroom of the input circuits etc. But still, they are great recorders, and they have a really distinct personality. For better or worse. When you work with it, you feel the different personalities of the designers: Kudelski uncompromising approach, where nothing is left to coincidence, and the equally uncompromising Quellets desire to keep things simple (both electronically and mechanically). The two men worked together briefly (very briefly...), and I think that they both acknowledged that they were just too different to have any real cooperation. But I am sure that they respected each other... I have no real conclusion about which is the better recorder, except that the Nagras are without a doubt more mechanically stable and forgiving... But history made its judgement, relegating Stellavox to extinction. Paradoxically, Georges Quellet is still alive, so he ended up outliving Stefan Kudelski, even though Quellets career was marred by his periodically bad health...
  13. With the risk of replying to a spam posting: The 3 screws are grub screws, and the threading is in the stabilizer roll itself. They press against 2 sintered bearings inside the roller, so if you loosen the screws, you can pull the roller exterior off and clean/lubricate. when the roller is reinstalled, remember to check that there is ca. 0.5mm clearing over the top plate, so it can move freely when it is disengaged.
  14. On the ATN supplies the ripple capacitor is often completely dried out. It can easily be replaced by a new capacitor (1000-2200 uF, suitable voltage), making the supply as good as new. And without hum.
  15. Did you find out more about the LEDs that are permanently on? I have the service manual in case you need it...
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