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dela

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About dela

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  • Location
    Copenhagen
  • Interested in Sound for Picture
    Yes
  • About
    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. I am pretty sure that if you remove the return spring, the braking function will be really bad... If the spring is not pulling the roller outwards, roller will move inwards (and release the brake) with even a very low tape tension. If adjusting the spring does not work, you might try to dampen the return spring with f.ex. a bit of soft foam tightly around the spring (since the diameter is too small for putting the foam inside it).
  2. Oops... I just checked with a scrapped 4.2 and discovered that I had mistaken left from right. The clutch is on the right reel, on the left reel the regulation is made with an adjustable brake. But the principle is the same, and actually the brake felt is a bit easier to check and replace on the brake than on the clutch system. But sorry about the confusion anyway...
  3. David is right that it is a common problem with the portable models, but unfortunately the service manuals are not really informative about how to solve it... The wobbling/oscillation og the roller is caused by the rather ingenious mechanical feedback system, where the left roller position is adjusting the left spool clutch. When the roller moves inwards (tape tension increases) the clutch is loosened (spool torque is decreased), because the movement of the roller is coupled to the clutch, using a metal arm between the two. It works really great if the clutch is working, but if f.ex. the clutch gets "sticky", the torque adjustment is not perfectly smooth, and you get the oscillation. The good thing is that it is not really serious (it usually goes away if you manually holds the roller, corresponding to dampening the mechanical feedback system). In my IV-S TC, which had been inactive for many years, it even disappeared by itself after a bit of use. Getting rid of it involves taking apart the clutch and replacing the grass og the greased felt in the clutch; it can (probably) be done, but it is not for the faint hearted på apply new grease, as it is a one-way street: Once the original grease is not there, the regulation might get even worse... But it will probably be a good idea to start with making reversible changes, so adjusting the tape tension (on the adjustment screw on the clutch arm) might be a good start.
  4. I think that diversions are what make this thread so interesting; just when you think that a subject has been covered, a new one pops up and kickstarts the fun...
  5. The Nagra E is exactly the same size as the IV/4.2 series, which is probably part of the reason they could manufacture it for at low(er) price: They could use the tools and materials used in the more expensive machines, and in that way don´t have large start up costs. But however nice the E was, the Stellavox recorders were more in the IV/4.2-class; I would guess that the IS would be more a Kudelski version of the Stellavox (and probably a more stable recorder). I don´t know the price point of either the Stellavox SP-7/SP-8 compared to the IS? I actually don´t think that there was a toolkit as such in the E, but there was a kit consisting of the most used components, as well as the test leads for the voltmeter-use of the modulo meter. But still very convenient... Regarding the sound quality of the QSEF, I would think that if your current signal source is properly impedance matched with the unbalanced input of the IV-S, everything should be optimal (if you don´t use long cables, that can pick up noise). In that case the QSEF will not improve the sound; it will merely be another step for the signal to pass, without doing anything good. I can´t remember if the QSEF is transformer based or it is a differential amplifier; if it is an active circuit, it is not impossible that there is a fault in it, but if it is transformer based, it probably simply is the transformers affecting the sound.
  6. The Nagra E might be less expensive than the 4.2/IV-recorders, but it is certainly not a "cheap" recorder. The materials are as good as in the larger machines, and the price was primarily reached by removing features not deemed absolutely necessary, and by mercilessly removing all non-essential things (f.ex. the rubber gasket around the lid) and simplifying the circuitry. So the core recorder is presumably as reliable as the larger siblings. Actually the E is the result of a quite modern approach, namely that the price of buying a device is one thing, but keeping it running for years is also a part of the "price" (TCO, Total Cost of Ownership). And, not least, that to make it work in the places where it was meant to be used (in developing countries or other locations without a really good acces to skilled technicians), you had to make an effort to make it very easily serviceable. Not only was there a component kit inside the recorder, but you could also make measurements without a voltmeter, and the main circuit board is very neatly laid out with very informative printing. Even the service manual is different: It is not only containing the raw service information, but it also explains a lot of the basic principles for the circuits in the recorder, making it almost a general tape recorder tutorial. So the E design was "sustainable" 30 years before the term became widely used... I have the service manual for the E, and if you send me a message with your mail address, I will send it to you (it is too large to put here, so it will be sent by wetransfer.com). I "only" have the E user manual in original paper form, but if I have the time, I will scan it in the weekend. And regarding the tape on your Nagra E: It is always really exciting to get tapes along the recorders, and I have found all sorts of strange & interesting things. F.ex. a live recording of a boat trip on the Rhine (complete with ambience recordings from the cafeteria, where german schlager Hammond-organ hits are played to a relatively indifferent audience). On a IV-S TC from Mali, Africa I found a recording of a very (very, very) thorough technial test and then there is of course the quirky test tapes, that sellers has made (I got a very touching rendition of old 60´ies hits on a recorder I bought off a foot therapist/Tesla coil designer/bird sound recorder).
  7. Yes, it is a fun fact, that the legendary SQN-3 was actually made to be used with a SN... Regarding the TRV, it was made for voice logging in. f.ex. flight control centers and radio stations, it was also used for surveillance. The only one I have heard of used in Denmark was used for debriefing airline pilots about meteorological data. It could play and record with an OK sound quality even with very low speed, and the quite advanced control system (borrowed from the TI) meant it could be used in automated setups. It was a niche recorder, but I definitely think that a lot more than 100 TRVRs were made. I think that the problem with finding them is that they never were "personal" machines, they were just part of an installation in a government/company setup. They were not used by people who had any interest in audio or sound quality, so when the installation was scrapped, very few felt the urge to save the recorders. Which is a shame, because they were quite advanced machines... I would also like to have one, but each time I have seen one, it has been in a really bad condition. I hope that one day I will be lucky, but you never know. A couple of months ago the Nagra JBR playback machine (PS-1) was hard to get, but within the last month 3-4 has been on eBay for a reasonable price. So perhaps there will also be a TRVT surge sometime...
  8. I couldn´t resist checking eBay, and I found it; the seller is certainly not underselling it... To call it a high quality swiss broadcast quality mixer is a bit of a stretch. It might be custom made for radio work, but it seems like an inhouse job at a broadcaster, and not really a particularly good one. The component quality is mostly OK, but the switches and potentiometers are mediocre, and not even as new would they be very good. By now they are probably corroded and need to be replaced, luckily they are still as cheap as they were from the start... The capacitors are of OK quality, but I would guess that all eletrolytic capacitors are dead and need to be replaced. It is built around germanium transistors, and the seller cheerily states that they are "selected". Which would probably be neccessary just to get the thing working in the first place... In short: It is a nice piece of DIY kit, but I certainly wouldn´t recommend buying it for using it, for that there would probably be much better mixers around. And if one would like to use it for a practical purpose, I think that there are better mixers available, and they wouldn´t neccesaily cost a fortune. One of my favourite brands (being danish that is not a surprise) is NP Elektroakustik; they made mixing consoles for Radio Denmark, and they are really, really good. And they look nice too: http://broadcastsupport.eu/products/17-audio-mixers/1320-np-elektroakustik-lv28/ I have one at home; I might be tempted to post some pictures of it. But there are a large amount of fine mixers from 1960-1980 around, and it is great fun to see, how imaginative and competent some people were.
  9. The ATN supplies are simple unregulated types, where one of the central components is a 2200 uF capacitor, that is quite prone to ageing and drying out. So normally I would start with changing that. Apart from that individual rectifier diodes can short, or (in extreme cases) the transformer can be shorted. But a good bet would be the capacitor; changing it is easy and cheap, and the same goes for diodes. The exact values and diode types are uncritical; just about anything will do. After changing the capacitor, it will probably perform as new (or better). On the ATN supplies there are two fuses, one for the 110 V section and one for the 220 V section. The 220 V section fuse is designed for half the max. current of the 110 V fuse, so if you replace a burnt 110 V fuse with the 220 V fuse, it will probably die quickly even if there is nothing wrong. So be sure to replace with the correct breaking current...
  10. A very nice machine... It is nice to see one of the early versions, where the pilot system was not really implemented yet, and there was room for the huge, but very well designed head covers. On most/newer Nagra III without pilot, you can see that it is actually just a III without the pilot head fitted, on this model there is no room for a pilot head. I also shows how brilliant the Kudelski designers were: Even on this relatively early version, the design seems "mature", and exactly the same design, with very small changes, were kept until the model was phased out 10 years later. There is absolutely no "prototype"-feel to it; they did their homework and designed it correctly from the very first products... Is it still working? It is amazing that the blue Philips capacitors are still working (they are on all mine), when other companies had serious problems with dried out and/or leaking capacitors. The only defective capacitors on any Nagra seems to be the english Plessey-capacitors in the ATN power supplies. but in the recorders they just keep on working.
  11. It seems that the one I had was one of the newer types with a ruby blade... Here is a picture of one:
  12. MarkC: I think that the erase head is made of a very hard resin material. I have rarely seen a worn erase head, so they seem to be quite robust... I have only once seen a recorder with the ruby tape cleaner installed, so it can´t really be that necessary... But a nice little accessory, and who would say no to having a ruby knife? The QDAN is a take identifier device, so that you can (when you record) assign a take number, and when you play back the tape, the corresponding take number is displayed on the QDAN unit. I have been looking for a manual describing it more in detail, but until now it I have not found anything. I will get back if something comes up. And, as JBond suggests, anything with a nixie tube is by definition great to have.
  13. The limitation in using the pilot signal for driving a "tape counter" circuit is that it is a mono phase signal, i.e. it will describe the speed of the rotation, not the direction. For that, you will need a kind of biphase signal (like the standard biphase signal used for controlling 35mm projectors etc.). So if you just read the pilot signal, it will only work if you don´t rewind. But if you slave you recorder to a film camera, which hopefully never rewinds, it will be accurate...
  14. MBM: Right now there is a Radio Denmark Nagra IS for sale here in Copenhagen: http://www.dba.dk/baandoptager-nagra-is-tran/id-1029164654/ My experience with dba. dk is that it is normally pretty safe (it is owned by eBay). Radio Denmark (DR) machines are usually quite well maintained; I have not seen any major faults on any of my DR IS recorders, apart from one with a rumbling capstan bearing... If you want a couple of "local eyes" on the recorder before buying, I could try to set up a meeting with the seller (who I know nothing about, so I will only be able to vouch for the recorder itself...)
  15. 600mhz equipment resale?

    I have frequently been working in Mali, and on the last couple of trips I have had a bunch of "EU illegal" Audio Limited and Sony transmitter/receiver sets in the suitcase as donations for the local film institute and the TV station. They are really competent people down there, but purchasing new equipment is often not an option, so the surplus gear have come to good use down there... It is very satisfying to give good equipment a second chance, and at the same time helping people.
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