dela

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...

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.

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).

Yes, it is a fun fact, that the legendary SQN-3 was actually made to be used with a SN... Regarding the TRVR, 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 TRVR surge sometime...

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.

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...

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.

It seems that the one I had was one of the newer types with a ruby blade... Here is a picture of one:

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.

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...

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...)

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.

A bit of mixed comments (after all there are quite a few differents subjects here...): I have enclosed a couple of photos of resp. wide- and narrow track heads. They show a wide track recording head and a narrow track playback head (with space for a pilot track in the middle of the tape. My apologies for the awful pedicure on the pictures... Just for illustrating the somewhat strange choices of the Stelladat, I have also enclosed a couple of photos of the inside of the Stelladat. From the bottom view photo of the base board it is obvious that Sonosax had no second thoughts about selling a near-prototype device. It shows that the company simply didn´t have the resources for designing a product that advanced, and when they tried, they couldn´t afford to scrap obsolete versions; they chose to add a multitude of corrections in stead. If you wanted to control the recorder using the AUX-connector? Too bad, it isn´t connected to anything on the inside. And the list of strangeness is long... But I still like it; despite (or because of) its shortcomings it is a wonderful transitional device, and as a stand alone DA converter it sounds really good. If I had two of them, I wouldn ´t hesitate to send one of them to live i JBonds great collection, but I have grown quite fond of it, and I hope one day to succeed in fixing it one day. I generally collect Nagras, but some recorders are too exquisite to not own. The same goes for the Mandozzi DART-2 recorder, also a little swiss masterpiece. Only 32 kHz sample rate, but with at fantastic build quality and, despite the low sample rate, a great sound. It´s also swiss, so at least there is a swiss theme. And David: If you ever get to scan the Stelladat manual, I would love to see it.

I would guess not, as the audio path is the same in both models. The only (very hypothetical) problem could be crosstalk from the TC system, but that will be easy to detect just by listening. Be aware that there could be quality differences between unmodified IV-S recorders, they were delivered with heads for either 2 mm track width (for pilot/TC models) or 2,75 mm track width (for non-pilot machines). The larger track width gives a slightly better S/N ratio, so if you compare a wide track IV-S with the X4S, the IV-S will be a bit better. But, to make things even more complicated, non-pilot recorders were sometimes fitted with narrow track heads, so that there was compatibility between pilot and non-pilot machines... So, to quote Beastie Boys: Check your head.

Speaking of Stellavox/Sonosax, I have a problem, that somebody out there can help me with? Some years ago I got a Stelladat with a defective transport system. I have been unable to find any information (service manuals, user manuals, schematics, anything...) about it. Does anybody know somebody who has any experience in servicing the Stelladat? This particular recorder was scrapped from a rental company after its bankruptcy, as it was alway defective. It went for repair, worked a couple of days and then died again, was sent for repair... and declared dead. But it would be nice to get it running again, for for the fun of it. As MBM writes about the interior of the Stellavox AMI48 mixer, the Stelladat looks great from the outside, but on the inside it is a bit of a mess.. And sorry for hijacking the Nagra thread; I promise to help it back on track.

I am trying to find out more about the Sound Assist device; it seems that the manufacturer is still in business (Danny Natovich Ltd.). I have contacted them in the hope that somebody still knows anything about it. I have some ideas about its functionality, but I would like to know more. And when I do that, I will certainly get back with a description. As a comment on the recent posts about the Nagra IS versions, I have found a couple of brochures describing the various versions. Or some of them... I can see that my own IS-TLSP is not mentioned, so who knows what other versions are around? But again: The Nagras were very costumizable, making it possible for clients to get the machines suited perfectly for their individual purposes. So countless variations were made. The most interesting variation is the ISS for playing back SN tapes. On the pictures of the heads and the tape path, it can be seen that the Nagra machines were a very universal platform. On the ISS-recorders all the mechanical parts are he same as for 1/4" tape versions, only a few parts are different or just modified. Except of course for the jog/shuttle function, which is exclusive for the 1/8" versions. A year ago I was in contact with a French owner of an ISS, but unfortunately I am convinced that he wouldn't part with it cheaply, and I am not a rich person. But I completely understand him... Nagra IS konfigurator 1.pdf Nagra IS konfigurator 2.pdf Nagra IS-N brochure 1.pdf Nagra IS-N brochure 2.pdf

Speaking of "Yacht"... One of my all-time quirky favourites: The Nagrafax. It was one of the first fax machines dedicated to maritime use, designed på print out weather charts via radio. This one actually still works fine, and it is still possible to find old weather charts uploaded to YouTube as mp3-files. Stefan Kudelski was a keen sailor, and he saw the need for a robust device for printing out "on line" weather info while at sea. This particular Nagrafax was used by the Bundeswehr; I think that they had quite a few of them, as I have seen other BUND-marked devices. It has an internal demodulator, so it will accept a standard audio signal (with encoded data), but the image quality is not really great. But still: It is a Nagra, as the rear view shows: It is the same motor as in the tape recorders.

I don´t know if the Nagra D qualifies as a rare Nagra? In Denmark only three of them were sold, so in my local context they are a bit rare. I have a couple of them, and even compared to present devices the Nagra D is remarkably well sounding. And mechanically it is also a joy to behold, so I might open one up and post some pictures...

When I saw a Nagra 4.2 IRT on eBay a couple of weeks ago I immediately became intrigued by it, and as luck would have it, I managed to buy it for an OK price. Fortunately the owner is also from Denmark, and he even shipped it for free. So now I have an IRT, and I have begun finding out what is so special about it. Apart from having green knobs... First of all I have been on a hunt for information on why it is named "IRT", and soon I found out that the IRT stood for Institut für Rundfunk Technik. This led me on what I presume is actually a wild goose chase, because I have now found out two things: - The modification is not necessarily made by IRT - The IRT does not denote the manufacturer but rather the type of timecode it accepts. The last point is actually quite interesting, because I thought that the only timecode in play here is the SMPTE TC (as in the Neil Stone and Harvey Warnke mods), but there was also another, lesser known, timecode format, (briefly) known as the IRT timecode. The IRT timecode format was meant as a way to create a timecode information that could be printed directly on the film in the camera (16 mm). It predates the somewhat more advanced Aaton timecode, which was widely used, but at the time of its conception, the technology was not so advanced that a great deal of metadata could be written and read. The creators of the IRT TC settled for marking one frame each second, because then they could write a complete set of metadata once a second (time, date, camera number etc). The information was printed between the perforation holes, 4 bits between each set of holes. This gave them 80 bits to work with, the remaining empty spaces were used for synchronisation. To cut a long story short: Both the camera and the recorder had TC generators, and they could then be synced using an external master clock generator. It was clever and not too hard to implement, but it did have one major drawback: If you were to make an edit within an image sequence of the 25 frames, the individual frame number would be lost... That, and of course the fact that the better/smarter format does not always guarantee success, meant that the IRT was not very used. But back to the present, and back to my 4.2: When I opened the recorder and checked the large "unoriginal" card mounted, I was a bit surprised to find out, that it was actually just a quite large carrier board for a normal Kudelski 50/60 Hz crystal generator. As you can see in the photo of the connector board, only a few of the pins are used. Another interesting thing is that the underlying connector board is also quite unusual. It has, in the best swiss and german tradition, all connection names printed on the board, indicating that signal-wise there are a lot of extra potential functionality hidden in this machine. If you have the proper IRT TC board... In the pictures the two original Kudelski boards (a synchroniser and a clapper control board) are removed to show the base board, so normally this recorder functioning as a standard 4.2. It seems that the Kudelski/IRT/whoever people who devised this modification made a rather costumer friend design. They knew that the IRT TC function would not always or rarely be used, so making an expensive recorder that was tied to an experimental TC format would be a commercially very expensive experiment. It would probably leave a lot of costumers quite disappointed, should the IRT format die a quiet death, making you an owner of a very expensive non-sync 4.2 So they made the modification optional and user-interchangeable: If you use it as a normal pilot/crystal controlled 4.2, you use the simple generator board. If you want to use it with IRT TC, you put in the dedicated IRT module. In that way your investment was safe whatever happened. I have recently seen another 4.2 with green knobs and stereo heads, and in this recorder a normal Kudelski generator board was somewhat unceremoniously put in to replace the custom carrier board. So I guess that the missing IRT TC boards is testament to the failure of the IRT format, and that most IRT recorders lived as normal 4.2 recorders. And this brings me to the next question: Does anybody have a IRT TC board? And who produced it? I hope to find out; not because I would have any use for it, but I always like to know more about all these deceased formats, that are left as roadkill along the technological highway. The attached pictures are just meant as illustrations, but one detail should be mentioned: On the picture of the main control switch, you can see an extra LED marked "Zeitcode Ein". It seems that this LED would flash if the TC generator was working properly, and it had been synced recently. So in this case, a flashing red light actually is a sign of safe operation... I know that this is a bit nerdy (my wife certainly thinks so), but I hope that at least a few people are also thrilled by the adventures of reverse engineering and information gathering, not on the Dark Internet, but certainly on the not so sufficiently lit areas. And in a few years some of the history is lost completely; I would like to do my bit to at least scratch the surface and document what I find out... Added note: I have just noticed that the part no. format on the carrier board is the same as the one used by Kudelski. So it might be an actual Kudelski product.

Regarding the bag, I have only seen two types: The original Kudelski-bag, which is fine except the zippers (as you found out) and a custom made bag, that Radio Denmark used in some cases. It was dark brown leather and much more sturdy that the beige original, but I have only seen one of them in real life (I have one...). It was actually distributed by the father of one of my collegues, but they are probably now long gone... So I would go with replacing the zippers on the original bag.

I can imagine that it would take some persuasion to make a customer change to a new recorder that forces him/her to change the entire range of accessories, and at the same time is limited to 5" reels. I don´t know the price point of the IS, but my guess is that it would be in the same rage af the 4.2, perhaps a little lower, but not much. So yes, a niche product more than a universal tool... I have been stacking up the machines today to show the front plates (and ears) of the different models. As you can imagine there is not much difference, but there are some. Mainly they are: - Right ear: The recorders prepared for pilot system has a pilot signal input socket (as the pilot board is missing, it doesn´t do anything) - The pilot indicator: Same as above - The ALC switch: Interestingly enough the very neat mechanical parts are installed in the ALC-prepared recorders, but the two-way knob is replaced by a blocking cap that prevents you from operating the switch. As with the pilot-prepared machines, you could modify the machine quite easily by replacing the ref. generator board with a board containing both the ALC and the ref. gen. On the "group photo" of the IS recorders, the different types are: Left side: Top: IS-DT Middle + bottom: IS-D Right side: Top + bottom: IS-TLSP Middle: IS-DE After I took the pictures and wrote the list yesterday I found a Kudelski brochure listing the different subtypes, and most of mine are listed there (the TLSP is missing), and I can see that the difference between DE and DT is that the DT is (as the only non-sync) a two-speed recorder, the other ones are single speed. Not the world most significant fact, but still a difference . And speaking of insignificant but still a bit intriguing details: I dug a bit in the service manual, and in there the unmounted connector in the cabinet cut-out is marked as for "accessories". It is placed on the reel motor control board, and the control bus signals for the tape transport (in- and outputs) are led to the connector pins (along with a power output). This just about confirms my thought that a large reel adaptor was planned, but never materialised. Sadly enough... For illustration I have enclosed a picture of the IS compared to its smaller and larger siblings. They say images don´t lie but, as JBond writes, when you see the IS in real life, the IS seems much smaller that the (in comparison) bulky and clumsy-looking 4.2. The 4.2 in the picture is, by the way, a work in progress: The electronics had been severely water damaged (the transistors just fell off like ripe fruit when you touched them), and I had actually given it up. But stubborn as I (sometimes) am, I have been nurturing back to near health, which is a great joy, remembering how it looked before...

Another long weekend at work, so I might as well fulfill JBonds wish for descriptions of a (small) variety of Nagra IS models. Mainly there are three versions of the IS: The non-pilot version, the pilot version and an intermediate model, which is non-pilot but prepared for pilot head and circuitry. As my machines are primarily radio recorders, they are all non-sync versions; I hope that I will eventually get a sync-version also... The versions I have are: IS-TLSP (2 P48 mic.inputs, prepared for pilot i.e. with pilot indicator installed) IS-D (Only dynamic mic. inputs, no pilot indicator) IS-DT (1 x P48, 1 dynamic mic inputs), no pilot indicator) IS-DE (2 P48 mic. inputs) The different types are almost identical, except the described differences. The IS-TLSP is also prepared for ALC (Automatic Level Control), shown by the (disabled) ALC control. Age-wise there are also some variations, just like on the larger types: Older recorders have all-steel tape guides, newer types has all-ruby guides; I guess that the even newer ruby/ceramics guides came later than the IS. On some of the machines a playback head shield is fitted, on others there is no shield. On the IS-TLSP the left tape roller has a rotating plastic part, where the D-types has a massive aluminium roller. All in all: Small and not very significant changes, but it still shows, that is was a model with a very long active career. I have attached pictures of IS recorders, and (I can´t help it, I am a technician) a couple of pictures of the inside of the IS. As you can see the mechanical and electrical build quality is the same as the larger types, so the IS is by no means a discount product (like the Nagra E). It is tightly packed, but still very serviceable, and high quality parts are (mostly) used. Unfortunately the rotary switches are not really great, and I have had to spend some time getting them to work properly, but apart from that there has been very few age-related problems. All my IS recorders has female mic. input "ears", but in some cases male XLR input connectors were used. It might be that there is a swiss parallel universe where microphone cables end in female XLR connectors but I have yet to meet one... Hidden underneath the battery compartment is a cut-out in the cabinet, usually covered by a metal plate. On one recorder it was covered with a sticker labeled "Only for use with large reel adapter", which is quite intrigueing, because I have never seen or seen any reference to such a "IS-QGB" anywhere. Perhaps they feared that a large rell-capable IS would cannibalize their market and dropped it before even releasing it. But it would have been a great addition. Later note: I have just found a picture of the missing label, showing the reference to the lost reel adapter. I have added it to the enclosed pictures. It is obviously an early version, so it seems that right from the start an adapter was planned, but was never made. I can´t help thinking that the IS partly was an attempt to make a design upgrade to the Nagra series, and if it had been sufficiently well received, the changes would have been introduced in the IV/4.2 series (or rather: A successor to it). As it happened, people preferred the simpler 1-motor design, probably because it was a very stable, time proven design, and thus the brilliant IS solutions were never used on other recorders. Nikon made a similar gamble when they introduced the electronic F3 to replace the tank-like F2; users were nervous that it would be unstable and ureliable, and moaned a bit about that. It turned out that the F3 was a brilliant camera and became an instant classic...

Rachel: Congratulations with the IS; it is a really nice little recorder. Small, but in every aspect still a Nagra. In Denmark (where I live) it was almost exclusively used for radio, so it is rarely seen in the pilot version here. For film work the 5" reel limitation was a problem, but many a Radio Denmark journalist loved not having to carry a IV/4.2 around. I can also imagine a journalist would hate having to transcribe an interview with the rudimentary tape winding system on the IV/4.2; here the IS motor controlled transport really shows its strength. I have been looking in my manual archive, and I have found an IS user manual, unfortunately only in german. I have an english paper version, that I can scan at work this weekend, if your german isn´t up to scratch. I also have a service manual, and that is in english. If you send me an email address, I will send them to you. They are quite informative, as you would expect from a swiss company.. The one problem that I can see with the IS is that (mechanical) servicing is quite a bit more complicated that on the larger recorders. F.ex. if you want to change the reel motor assembly, you need a special measuring gauge to adjust the position very precisely, and even with that it should not be quite time consuming. On the larger machines, the tape transport was built around a very sturdy steel plate, so virtually no mechanical adjustments of the position was necessary. The small, all-aluminum chassis came at a price... But still a marvellous little recorder; I have 6 of them in various versions, and I love them all. The cuteness-factor of the SN is undeniably larger, but it is a bit like choosing one of your children over the other (but, having just about all available types on the shelf, I can enjoy not having to choose). And by the way: I couldn't´resist buying the 4.2 IRT, so I will get back with some more info after I pick it up next week. I haven´t heard from Institut für Rundfunk Technik, so I will probably have to figure it out myself how to use the TC system. Fortunalely I have salvaged a scrapped Alpemann & Velte TC generator/reader, som I am prepared for everything. And looking forward to it.

I had actually thought about the Neil Stone modification; it seems to be the same principle as in the IRT 4.2... I have just had a 13 hours watch at the TV station I am working on, so I have had a bit of time to look for more clues. And in another forum (Gearslutz), I found a reference to a 4.2 modified by IRT, which I completely had forgotten stands for Institut für Rundfunktechnik. A bit silly, as I am regularly receiving updates from them after buying some very expensive software from IRT. It seems that they were equally inventive back in the days of the 4.2, because they made a modification with an extra board that generated a short TC burst when going into record. You could then jam sync a TC generator when transferring it back home. This sounds reasonable, as the 4.2 IRT currently up for sale is from WDR (West Deutsche Rundfunk). Judging by the details on the IRT machines (ruby guides, tape counter roller) it seems like they were modified somewhat late in the 4.2 life time cycle. So it seems that it is not a real Kudelski mod, but a very capable one, that was made on quite a few machines. But still nowhere near the sheer brilliancy of Harvey Warnkes superb TC mod. I know that I will get one eventually; it would be great to add that to the collection. And thank you for you comments; I imagined that I would get some very insightful answers.

I know that I should probably start a new thread about this, but nonetheless I have something that I would love to find out more about... Once in a while I have come across eBay listings of the Nagra 4.2 IRT, which is a bit of a mystery to me. When you look at a 4.2 IRT the only immediately unusual thing about it is that the function switch and knobs are green in stead of the usual black. But another significant feature is that it has stereo heads in stead of the usual mono heads. Yet another indication that something is different is a little indicator light near the function switch marked "Zeitcode". So I guess that it is a 4.2 modified to record and playback LTC, and since the LTC is put on the middle track, the playback head gap must not cover this track, and thus they use a stereo head (for a pilot/TC IV-S, with broad guard band) with the two tracks paralleled. But that is just my assumption; I have seen them both with a normal crystal generator board and an unknown, more advanced board installed on top of the battery compartment. Does anybody know if the 4.2 IRT is an "original" Kudelski version or a third party mod? Or just anything at all?I am really curious...