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Pass Aleph 3

Discussion in 'classic' started by Tony L, Sep 10, 2021.

  1. Robert

    Robert Tapehead

    Blimey, what's the junction temperature going to be?
  2. russel

    russel ./_dazed_and_confused

    I think I calculated it at about 150C.
  3. gingermrkettle

    gingermrkettle Deep vein trombonist

    And what's the temperature at the caps?
  4. russel

    russel ./_dazed_and_confused

    I reckon about 35C
  5. mandryka

    mandryka pfm Member

    How do you get the source into the two amps? Do you have something which splits the source into two streams?
  6. G T Audio

    G T Audio Trade: Manufacturer and Distributor

    The Verdier Control B has adjustable gain via links inside. The links vary the amount of feedback applied to the output stage. The higher the gain the better it sounds as there was less feedback applied. The lower the gain the worse it sounded due to the increased feedback. Verdier was working on another output stage which he sent me to evaluate in my demonstrator Control B (I believe the one you have Tony). The board he sent me (I still have it) has a fixed gain and no feedback. I am not sure if he ever put this into the later Control B's. I doubt he did. I thought it was a huge shame no one, well a few, probably about 3 bought Control B's in the UK, as it was clearly a very nice preamp, but at that time that market was served by Croft, Art Audio etc, but those were no where near as flexible as the Control B, or to be fair, as nicely engineered.
    Tony L likes this.
  7. G T Audio

    G T Audio Trade: Manufacturer and Distributor

    My experience of Class A solid-state amplifiers is that they need time to warm up. Anything from about 1 to 2 hours is about right. My Mark Levinson ML2's used to take 2 hours to start to work well.
  8. Tony L

    Tony L Administrator

    The revised Verdier board sounds interesting! The B was certainly replaced with a later version, the ‘Control B Evolution’, which looks very different inside.
  9. Rug Doc

    Rug Doc pfm Member

    I use an Audiolab 8200cdq which has both RCA and XLR out which can be used at the same time.
  10. russel

    russel ./_dazed_and_confused

    I am not sure you can blame it on higher feedback, feedback is a tool, used properly it does not degrade sound. Pretty much all the music people listen to has passed through mixing desks containing dozens of op amps using high levels of feedback, to have it suddenly start making a huge difference in the final stage does not add up, same applies for foo cables, roll up at a recording studio trying to sell magic cables and they would just laugh and carrying on buying Belden XLR cable in 100 meter reels.
    Robert likes this.
  11. mandryka

    mandryka pfm Member

    Ah that simplifies things!
  12. Tony L

    Tony L Administrator

    I wanted to double check this as it made no sense to me so I stuck the LS3/5As back in yesterday. There is something to what I say above, but it is way more complex than it appears and the LS3/5As do actually sound superb. Their added bass warmth enables a slight listening seat position change (a bit further back), and that done they match very well with the Pass. Listening late on with the lights out was stunning, they really do cast a natural, wide and deep soundstage and peel back every layer of a recording. This is a very ‘grown up’ system, very far from the low-resolution flat-earth foot-tapping frenzy favoured by some dealers etc. It is initially unimpressive, but the more I listen the more I realise absolutely everything is there with nothing hyped-up or exaggerated. It just lacks artifice, it does not seek attention, it doesn't push anything forward at the expense of anything else. There is no ‘look at me’ hype, just balance. It is remarkably good. In comparison the JR149s push the mid-band out more, they superficially sound more dynamic and bigger (and I suspect they are), smack the snare more, stick the sax or trumpet forward, but that comes at a price of ultimate midband neutrality. Voices, piano, applause etc just sound a bit more ‘real’ on the LS3/5As. I’ve long felt the LS3/5As more successfully dial-out the B110’s ‘quack’, there is just a hint that remains on the 149s.

    I plan to bring the TV rig Spendor S3/5R up next, though I’ll leave the LS3/5As in for a few days first to get used to them. I’ll be very interested to see what the3/5R do on this amp being a far more modern speaker with a more usual 6-8 Ohm load.

    PS I also plan to drag it down for another go on the Tannoys at some point as I think I’ve come to the conclusion it a) prefers the Audio Synthesis passive to the Verdier, and b) the Marantz SACD player works better into the passive than the DPA DAC, i.e. I may well not have setup the best system I can with the components I have to hand yet. I’m also aware that I may not have the right preamp at all yet. I’d really like to try one of NP’s own designs; Aleph, First Watt, Threshold or whatever.
    chiily and cooky1257 like this.
  13. a.palfreyman

    a.palfreyman pfm Member

    Must admit Tony that I keep coming back to this thread with envy...
  14. G T Audio

    G T Audio Trade: Manufacturer and Distributor

    Yes, indeed Tony. The revised version is different from the earlier one I used to sell. Fundamentally I don't think they are too dissimilar. The prototype line stage board I have here has 3 x 12AT7s fitted. I will double check on the design but I am sure it had a fixed gain.
  15. Tony L

    Tony L Administrator

    It’s a strange one as it is, like so much audio, a learning curve. I hope that’s coming across in what I write. I’m not attempting to provide any absolute statements or qualitative judgements, just document how my perception is not set in stone, but shifts with further understanding of context/intent. It can also be seen as my current view that short-term exposure to a product (dealer, show etc) is so far beyond useless it is a waste of time. It takes weeks or longer to understand something IMO. My initial response to this amp has shifted from a “yeah, class A? So what’s it doing that say a Quad 405 can’t?” to realising that there are whole other layers going on in there that really don’t shout for attention. It is a remarkably subtle component. No shouting, no attention seeking, superficially quite bland until the penny starts to drop what is actually missing is artifice or character. The comparison to the little Leaks is fascinating as they sound so instantly appealing and nice, they just sound amazingly good, but they do bring a character and I’m coming to the conclusion I can actually hear more through the Pass. In a quick AB I’m prepared to bet 8 out of 10 people would pick the Leaks. I’m lucky in that I don’t have to, neither are going anywhere!

    Same tube layout as the original. I’d be interested if he did anything beyond hard-wire it to the higher output/lower feedback level. I do actually love that flexibility, it makes it able to partner anything aside from the crazy high-gain Leaks.
    G T Audio likes this.
  16. G T Audio

    G T Audio Trade: Manufacturer and Distributor

    That is where you are quite wrong. Feedback has a massive effect on the sound. As for your studio comment, well Mike Valentine was able to persuade the guys at Air studios to take a listen to his "audiophile" cable which he wanted to use for one of his recordings (pre Nordost time). The sound engineers said they could hear the difference, but they do not have the purse strings to buy the equipment in the studio, or have a say in what is used above and beyond what they use day to day. Recording studios are all about making money, not necessary quality. They want to process the recording and mastering as quickly as they can, so they can move on to the next client. Audiophiles and great sound are not a requirement of any studio, except if it comes as a requirement of the job in hand, as it did with Chasing the Dragons Big Band Jazz Spectacular direct cut album. I've been at Air Studios and have been involved in a couple of recordings so I know.

    Re mixing desks: you also might want to check out why certain desks have a cult following and why they go for such high sums when they become available...
  17. G T Audio

    G T Audio Trade: Manufacturer and Distributor

    I agree Tony. It was one of the reasons I took it on back in the day.
  18. russel

    russel ./_dazed_and_confused

    I didn’t say feedback didn’t affect the sound, I said blaming poor sound because of high feedback was possibly wrong. If you go back in time when transistor amplifiers first came out they used to boast of high feedback, however because of the very slow speed of the output devices of the time they had to reduce the amount of feedback with frequency, so early transistor amplifiers had high distortion and because they claimed high amounts of feedback poor performance was blamed on high feedback even though at the frequency of the distortion very little feedback was taking place, unfortunately this is still believed today even though better quality devices are available that allow use of higher feedback levels.
    earlofsodbury likes this.
  19. Tantris

    Tantris pfm Member

    You've described very nicely what I've found with my Pathos Twin Towers / ESL63s - there is no exaggeration, or synthetic layer to emphasise a particular aspect of the tone or timing. It's most obvious when listening to a recording in the early morning hours, at low-ish volume, when there are few other distractions. I do like the way you are describing this amplifier.
    davidjt and chiily like this.
  20. earlofsodbury

    earlofsodbury Wastrel.

    Apols to others for going OT, but there's nothing imaginary about it - DC offset causes significant saturation magnetostriction in most mainstream power transformer types. That drops transformer efficiency significantly - in excess of 90% is not unusual - the upstream effect of that will be audible to varying degrees depending on the demands being made of the PSU. We only tend to notice the DC offset when it affects physically large transformers where the magnetostriction is of a magnitude that it becomes audible as a 50Hz (or 60Hz) buzz.

    PS: it's so 'imaginary' that Bryston - a company known for its studio-oriented designs - include a DC blocking circuit on most of their power amp PCBs...
    Wilson and mandryka like this.

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