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Audible Illusions Modulus 3A Replacement Valves

Discussion in 'audio' started by John Lamb, Jan 21, 2021.

  1. John Lamb

    John Lamb pfm Member

    Hello and a good day to all, I have just purchased the aforementioned pre amp, I'm trying to source a set of replacement valves but don't know where to start or what I should look for any help is most welcome.

    Thanks guys John
     
  2. Vinny

    Vinny pfm Member

    What is in it now?

    One source online states that original valves were NOS 6H23NEB (Russian valves), supposedly equivalent to ECC88, although 6N23P is supposed to be that too.

    6N23P are extremely cheap if you buy a few.

    As the amp appears to only have 2 valves, I would not expect major changes, if any, in sound just by swapping valves.
     
  3. John Lamb

    John Lamb pfm Member

    I think it uses 4 valves it will arrive on Tuesday next week I meant to ask for a supplier in the UK or Europe who could provide me with a balanced matched Quad. Sorry for the confusion
     
  4. Vinny

    Vinny pfm Member

    Depending on what they do/circuit design, matched valves may well be a waste of time and money. A lot of folklore about valves is exactly that - folklore.

    That apart, there are numerous suppliers, including on EPay that will ship matched quads of Russian valves, but not the original 6H23NEB

    ECC88 are still made and NOS ECC88 are not too expensive compared to ECC82 and ECC83, but the chances of getting matched NOS must be VERY slim at almost any cost.
     
  5. Vinny

    Vinny pfm Member

    Apologies - yes 4 valves. That said, to my highly ill-trained eye, it looks like a SS pre with 4 valves in it.
     
  6. Yomanze

    Yomanze pfm Member

    The Audible Illusions preamps are known as being "tube eaters". I sold a matched & balanced pair of these (another project I didn't get around to...), which are supposed to be the ones for the job, and you know you are getting the proper ones from these guys, whom I've bought from a few times now:

    https://www.thetubestore.com/6h23n-eb-6922

    The NOS 6H23P-EB (Premium) tube is a very noticeable upgrade over the Sovtek 6922 tube and Electro Harmonix 6922 tube. They are incredibly durable and can handle the punishment of modern pre-amps, including those made by Audible Illusions. They excel in detail, speed, and soundstage. The highs have air and sound natural.
     
  7. John Lamb

    John Lamb pfm Member

    Thanks for the replies guys I'm going to get the pre amp and then put it through its paces.
     
  8. clap

    clap pfm Member

    You won't be disappointed. I have a modulus 2b linestage which I have had for maybe 8 years. It is superb. Superb build quality, low faff and beautiful sound. The adjustable gain is very useful. They are susceptible to hum if placed neat transformers so give it some space. Once plugged in from cold it will take some time to settle in and sound it's best. Enjoy. Art the manufacturer sells valves but his prices are steep. I should say that he very kindly sent me a free set on one occasion. He is anal about matching them. He has done a whole lengthy tombe on how to match them in the manual. They do only last a couple if years. I had Amperex for a bit but the Russian ones are what you need.
     
  9. greengoblin

    greengoblin pfm Member

    Ah you must have bought the one off eBay which was a sensible price. Some are selling for silly money

    I had it around 10 years ago. It runs 4 ecc88 so plenty around especially new. I’m not too convinced the merit of matching them

    the phonostage was quite specially and has the ability to allow you to slot in resistor for the loading is needed

    the only issue I had was matching a power amp with correct sensitivity. At the time I had an art power amp and I only had 2 clicks of volume control to play with
     
  10. Yank

    Yank Bulbous Also Tapered

    As I recall the gain staging is a bit odd. They could only manage about ~30dB @ 1KHz gain for the phono stage from 6DJ8s, so they boosted up the gain of the line stage to +30dB to make up for it. The phono stage is quiet enough to tolerate having that much gain after it, but this results in excessive gain for line level sources. For CD/DAC/Tuner I'd suggest voltage dividers on their respective inputs.
     
  11. John Lamb

    John Lamb pfm Member

    Well I hope I haven't overdone it as I'm using Tube Technology Genesis Monoblocks @ 100w per channel gulp :oops::rolleyes::):):)
     
  12. clap

    clap pfm Member

    Don't panic I'm using ancient Classe Monoblocs that are 400w at 8ohm and 650 at 4 ohm when used as monos.
     
  13. greengoblin

    greengoblin pfm Member

    It’s about the input sensitivity of the power amps rather than their output. I saw that the genesis might be 0.75mv so quite sensitive. You might not have too many clicks on the volume control to play with and might need to think about some Rothwell attenuators?
     
  14. John Lamb

    John Lamb pfm Member


    Thanks for the reply, if I may ask which attenuator version should I get 10db or 20db.
    I'm no good with electronics but love listening to music.
     
  15. Yank

    Yank Bulbous Also Tapered

    How many sources do you run through the preamp?
     
  16. John Lamb

    John Lamb pfm Member

    I have got Gyrodec turntable, Cambridge CXN steamer, Cossanance Orpheus cd player.
    I thought that you just have to attenuate the power amp input or am I missing something??
     
  17. greengoblin

    greengoblin pfm Member

    Probably best to get the preamp first and see of course. You may not need any. In the past I’ve used -10db attenuators on the power amp input to drop the gain in the system to allow more clicks on stepped volume control
     
  18. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I believe they use the ECC88 without feedback but with the two triode sections in parallel... Mu of ECC88 is 33 so allowing for no current source at anode (just a load resistor) then indeed the gain is going to be in the area of 28-30 X. That's loadsa gain!

    An attenuator of fairly high impedance should be used to avoid loading down the pre amp and causing excessive distortion. 20dB will reduce output by 10\X and should be fine but look for input impedance (actually resistance...) of 10K or more.
     
  19. clap

    clap pfm Member

    They use 6922s. Don't know if that changes the specs at all?
     
  20. Vinny

    Vinny pfm Member

    6922 is one of the several and various versions of an ECC88 - electrically essentially identical. Current manufacture routinely have both stamped on them.
     

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