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RSD valves?

Discussion in 'audio' started by Mullardman, Dec 2, 2020.

  1. Mullardman

    Mullardman Moderately extreme...

    Asking for a friend. He has been told that RSD ECC83s are 'amazing'. All I have gleaned so far is that RSD seems to be a 'tube re-brander', in the mould of .say..Edicron, but a German outfit.
    Anybody know more?
  2. Euan

    Euan pfm Member

    From another site.

    "RSD is a rebrander based in Germany, Frankfurt area.
    Often very cheap East-German and ex Soviet-Union tubes are offered.

    Quality varies as they are mostly concerned with export orders to
    "third world" countries on an exchange basis.
    Audio quality is of absolutely no concern to them, price is."
    Mullardman likes this.
  3. mountain biker

    mountain biker The hills are alive

    I think your friend my be getting mixed up with RFT they will be NOS now and were German and indeed are supposed to be very good. I have an EZ80 rectifier it is fatter than all others and the plates split half way twisting into 90degrees looks amazing and glows well.
  4. Mike P

    Mike P Trade: Pickwell Audio

    I've got some. Mine have spot welded plates, copper rods and the little metal foil 'dog-tag' which I believe identifies them as being from Tungsram.

    They are a nice sounding tube.
    Last edited: Dec 2, 2020
  5. Mullardman

    Mullardman Moderately extreme...

    RSD exists. It may be that they have supplied nos RFT but they seem to have other makes too.
  6. Vinny

    Vinny pfm Member

    RSD was (is???????? possibly resurrected?????) a German electronic component stockholder/supplier as are RS, Farnell and others now. They did no more than Orion, Zaerix, Bentley, Pinnacle, CVC, Elpico, Solus, Lamba, and countless other companies did, and companies like Watford Valve do today – they buy valves wherever suits their needs and brand them.

    Back in the day, probably the most prolific European suppliers into the stockholder market were Tungsram and the E German (DDR) producer, known variously as RFT, RWN, Erfurt etc. etc. (which was based around pre WW2 Siemens factories, but produced at least double triode valves of internal design totally unconnected to Siemens). The RSD valves that I have, I believe, based on memory, were made by Tungsram – very easily determined by the metal date code flags welded to internal valve framework.

    To describe RSD valves as being good, bad or indifferent, or anything else, is just more valve nonsense and folklore as they did nothing but stick their logo onto valves made by other companies.

    The total nonsense spoken about valves will presumably continue so long as any working valves from pre 1975 or so exist to be sold.

    People even speak of “Philips valves” in hushed tones and yet they manufactured valves in numerous factories, tooled Ei (in the former Yugoslavia), and a good deal of the Japanese valve industry post WW2. So what does a “Philips valve” mean.

    Strange indeed also, that the likes of Tungsram and RWN/RFT double triodes that were treated with disdain for audio use until 1-2 years ago, have suddenly become highly thought of/expensive. Unlinked to the fact that they are amongst the very few manufacturers not in very short supply?

    To talk about any old stock double triode as being produced or tested in any way connected with audio use is also pure fantasy. Double triodes were work-horse valves for electronic machines and produced in their millions upon millions upon millions, across the world. Back then, music was mono, and at least one contributor here is on record that he has not known a preamp valve fail, ever. Quite how any manufacturer would test any valve for audio use would be quite some challenge given the plethora of circuits that they might be used in, and would be an interesting exercise.
    Last edited: Dec 8, 2020
  7. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    /\ You would check for noise and microphonics and that's about it. The lower the signal level the more important and relevant this becomes... How? Put it in the amp and listen for hiss, rustling sounds and for how much noise is produced when you give the valve a gentle tap!
    Vinny likes this.
  8. Vinny

    Vinny pfm Member

    Subtle edit, Jez - "anyone" to "any manufacturer".
  9. Mullardman

    Mullardman Moderately extreme...

    I did say in the OP I was asking for a friend.. and I was. A chap known to some of us on here... loads of money but a bit impressionable. I also think I clearly signalled that I was aware of the whole 'rebranding' thing.
    But..whatever.. I've done my bit for my friend. He can now move on as he wishes.

    Thanks for all the input.
  10. G T Audio

    G T Audio Trade: Manufacturer and Distributor

    That is not strictly true. A number of valves were designed specifically for audio use, as they were also designed for use in RF and VHF. The transistor only started being adopted commercially in the early 1960s (Leak Stereo 30 etc) so before that from about 1920 to 1960 we still had audio products, or products with valve amplifiers in them (Radio, TV etc) to warrant specifically designed valves for audio use.
  11. Vinny

    Vinny pfm Member

    True, but if you ask on a valve radio/equipent forum, as I did, you get the answer that the double triodes were work-horse valves used everywhere. No old valve at all common now (all the common ECC series) was ever anything but. The numbers going into "HiFi" audio equipment back in the haydays of valves was trully minute - they were commonly used in mono systems and all but never fail. The VAST bulk of them went into non-audio use and those that did go to audio use, most went into somewhat less fussy/crtical uses than the then equivalent of HiFi.

    The ECC83 was designed for audio use, but it was used EVERYWHERE.
  12. G T Audio

    G T Audio Trade: Manufacturer and Distributor

    OK then, where does the vast majority of NOS valves/tubes come from today? They come, or came from the MOD, or JAN in the USA, as in military use. Valves were mostly used in communications equipment and radar. I worked in the GPO (BT as it is now known today) and in the days of Strowger. We used a few valves, some in relays sets for sending and detecting tones and also in the generation of tones, ring tone, engaged tone, and ringing current to make the phone ring at your house. The latter was done using a few KT88's, basically a valve audio amplifier. 99% of the equipment in the telephone exchange was mechanical and this was the case up to about 1980. Most valves used back in the 40's 50s, 60s and 70s were used for audio or radio use. Most machines back then were mechanical and didn't use electronics.
    Last edited: Dec 9, 2020
  13. Tony L

    Tony L Administrator

    I’d have thought the overwhelming majority of valves were developed for audio use; radio, communications, sound recording etc, both military and civilian. What are the other uses? Before computing came along I can only really think of lab test gear, oscilloscopes, signal generators etc, which mainly existed for developing the former! Radios, televisions, PAs, mixers, transmitters, guitar amps etc would have been the bulk of it, surely?

    Here’s a fascinating RCA valve TV promo from 1956:

    The Computer History Archive Project is a really good Youtube channel with loads of amazing footage of early technology in action.
    BrianPK and G T Audio like this.
  14. G T Audio

    G T Audio Trade: Manufacturer and Distributor

    Exactly Tony. There weren't many other uses...
  15. Mike P

    Mike P Trade: Pickwell Audio

    Here you go:

    [​IMG]P1110892 by Michael Pickwell, on Flickr

    Note the copper rods, spot welded plates and metal foil date tag which marks them out as being Tungsram production if I'm correct.
  16. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    The vast majority of valves were designed for and used in RF applications. Audio is easy and virtually anything will do. At RF, and especially as frequency increases (the driving force behind the creation of many new valves!), interelectrode capacitances and electron transit time become more and more critical. Comparatively few valves were developed specifically for audio in the big scheme of things.

    We can place the development of many new valves and thermionic technology to even specific times and specific new requirements, mostly RF as I said. Look at the development of the then uber hi tech EF50, "the valve that won the war". It was then the highest spec pentode for use in IF strips and developed (in Holland by Philips) to improve the performance of the new fangled thing called TV. As time went on higher performance valves superseded it and then each other.... EF42, EF80 and then last EF184... all for the same purpose, all for RF, each better than the last, and yes they could and have been used in audio.

    Similarly, pentodes were used as RF amps at the front ends of radio and TV receivers, sometimes those above but mainly others which were optimised for this purpose. They themselves were superseded as VHF and UHF came in by double triodes used in the cascode configuration, ECC81, ECC84, ECC85 then a leap forward with the frame grid ECC88 and then, in usually grounded grid, the Nuvistors.

    Triode-Heptodes such as ECH81, earlier Triode-Hexodes such as ECH35 etc etc were developed as "frequency changers" (oscillator and mixer of a superhet receiver).

    There are entire series of valves which were used widely in TV and Radio which one never hears of in audio... Mazda ones with "30p..." and "30F..." and odd bases with a bayonet type fitting and before that ones with "Mazda Octal" bases...

    Loads with P or U first letter which had "strange" heater voltages for series heater chain AC/DC TV's and radios etc.

    Then as now hi fi was a geeky and expensive pursuit but every home had a "wireless set" and then all aspired to a TV set.

    I would guesstimate that there were 100 valves for RF use in radio, TV etc for every valve intended specifically for audio!
    Vinny likes this.
  17. Barrymagrec

    Barrymagrec pfm Member

    The Mullard EF6 / EF36 was introduced as an RF Pentode but it was found also to work well as a low noise AF amplifier so subtle improvements were made leading to the EF37, EF37A, EF40 and finally the the well known EF86 which was marketed as a low noise AF Pentode - but to all intents and purposes is the same valve.

    To be honest I was never much of a fan of the EF86 but that`s a different story.
    Vinny likes this.
  18. Vinny

    Vinny pfm Member

    ....and, truth be told, if the modded valve - the EF86 and predecessors - were still as suitable for RF and cost much the same to produce, the production lines made EF86 all the time, but the majority being stamped as the RF equivalent - been there, done that (with lamps).

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