Preamps

Discussion in 'Preamps' started by sphinxvc, Sep 21, 2016.

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  1. Turdski

    Turdski New

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    I'm in the same boat. I have a lot of really fantastic, quiet, detailed, and neutralish 6922-equivalent tubes, and I can't really be bothered to venture down yet another tube rollin' rabbit/black hole with the 6SN7s. I could live without a remote. Tubes might add a bit of magic that the second-hand Ayre K-1xe preamp I'm eyeing may lack, ever so slightly. I've read a couple of reports now of Mjolnir 2 not being as dynamic, or imaging as well, as the Freya with great tubes. Having said that, it sounds as though a wee bit of transparency is lost through the tube stage of the Freya. And finally, for the foreseeable future, our music listenin' room and movie watching room will be combined, so for home theatre duties, I'd be burning through costly tubes on the Freya, as it doesn't otherwise convert single ended to balanced unless the tube buffer is on. I realize it lacks a proper pass through feature, but I plan to manually get around that. It sounds like the Freya will deliver more in the way of hiss by doing this. Being in Canada, it's costlier with the dollar here, added shipping, and duty and brokerage.
     
  2. sphinxvc

    sphinxvc Gear Master (retired)

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    To my surprise, I was able to get what I would call "better resolution" out of Freya's active mode this weekend (compared to passive). Switched to a complement of 2x NOS RCA 6SN7s from the 1940s or 1950s (can't recall) for the gain stage, and stock tubes for the output stage (to keep costs down).

    I would say the active mode is now presenting just as much information as the passive, but in addition it's also making it easier to delineate concurrent 'lines' of music. Standard tone benefits of active mode still apply too. Win-win I'd say.
     
    Last edited: Feb 21, 2017
  3. svperstar

    svperstar Acquaintance

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  4. Daveheart

    Daveheart Friend

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    That'd be rather inappropriate as a preamp for home audio use. It's meant to take mic level preamps (measured in mV) rather than line level inputs (measured in Volts). All of the outputs are balanced as well. Essentially it's for a 100% different application.

    A Schiit Saga would be more appropriate (though not particularly tubey). There are also plenty of tube buffers out there or used full function or line preamps that would work depending upon how much "tube sound" you want. Really the easiest rec would be to just replaced the Asgard 2 with a Lyr 2 or something of that ilk.
     
  5. Daveheart

    Daveheart Friend

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    If anyone is in the market for a truly full function vintage preamp, keep your eye out for a good deal on a Sansui CA-2000. They were packed with utility and have possibly the most baddass volume knob ever made. It's not quite as transparent as the Audio Research and Modwright that I've owned, but I think the only remote function you could ask for in a modern update would a mute function. The knobs and switches are worth the effort of getting out of your seat.

    [​IMG]
     
  6. bilboda

    bilboda Florida boomer

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    Excellent thread and info. I was looking for a solution for my setup. Modi Multibit and HD Radio to SYS to Ember HP amp used as pre to feed Adcom GFA 535.

    My problems were the Ember would have to be on all day. I work from home, listening to music, radio,etc. And I was going thru 2 volume controls as well
    And to cap things off, the Ember's pot has volume mismatch at low levels. I would attenuate at the SYS to get a higher setting on the Ember.

    Tape out is common on active preamps but not so common on passives. I found what I was looking for on Ebay here http://www.ebay.com/itm/271214681553
    He has a decent variety of passives. Now I feed my sources to the pre and use tape out to my Ember for headphone listening.
    It's solidly built, sounds better than the previous setup, soundstage is deeper, wider and more centered. pics
    [​IMG]
    [​IMG]
     
  7. Dino

    Dino Friend

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    I've had my eye on that exact unit, @bilboda . Great to get a user impression on it!
     
  8. mrflibble

    mrflibble Friend

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    I was looking for a high quality balanced preamp for active monitors and I came across this on ebay:

    http://www.ebay.co.uk/itm/High-Accu...ced-Potentiometer-Passive-Preamp/253001325754

    I believe it utilises relays for precise volume control in a similar way to the Schiit Saga and Freya preamps. It is described as passive but I guess it requires power for the relays to work. What do you guys think? Any thoughts or opinions on its quality (from looking at the circuit board images)? It looks like it could be a good option if you don't require the multiple inputs / outputs or the tube buffer of the Schiit gear.

    https://ibb.co/he4AVb
     
  9. purr1n

    purr1n Desire for betterer is endless.

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    Input impedance 2k+? Seems very low.
     
  10. mrflibble

    mrflibble Friend

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    Thanks @Marvey . I'm somewhat ignorant about impedance. I assume the input impedance needs to be similar to the output impedance of the source (in this case, Gungnir Multibit)? What happens if it's too low?

    The quoted input impedance of "2k+" is somewhat ambiguous and seems to imply that it could be higher. I could ask them to clarify.

    For the time being, I will set up a software volume control in Linux - much cheaper :)
     
  11. sphinxvc

    sphinxvc Gear Master (retired)

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    Check the OP, in a spoiler called "Marv on impedance..."
     
  12. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

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    DAC output stages are designed for high impedance loads, usually 10K or more. Presenting a low impedance, say - connecting a pair of 32Ohm cans will ask the output stage to source more current than it can and it will most likely clip. Even if it will not clip, the circuit will not perform up to spec unless it's been heavily overengineered.

    The thing with stepped attenuators is that they vary in input impedance depending on attenuation level. I think in this case we're dealing with 2.2-10kOhm Zin circuit.
     
  13. Cspirou

    Cspirou They call me Sparky

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    @mrflibble

    I checked the specs of the preamp and it says input impedance is 2k and output impedance is 300 Ohms. 300ohms is low enough for most power amps unless they have something crazy low input impedance like 3k. Gungnir Multibit has a 75ohm output impedance so it’s actually ok with the 2k input of the preamp if going by the 10:1 ratio rule.

    My only real issue with the preamp is the lack of remote control. If going full electronic, adding remote ability shouldn’t cost that much more.
     
  14. Armaegis

    Armaegis Friend

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    The shunt types do that, but the series and ladder types do not.
     
  15. Cspirou

    Cspirou They call me Sparky

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  16. purr1n

    purr1n Desire for betterer is endless.

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    Best is to have as much information as possible. I like to see stuff like input Z and output Z range from X to Y, high points and low points at A and B knob positions, etc.

    Hard to say if a preamp is needed for best performance. Zout and Zin give us a rough idea, but in the end, it's subjective.
     
  17. Mshenay

    Mshenay Barred from loaner program. DON'T SEND ME GEAR.

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    Aside from reading through 7 pages worth of content, has any one take the time to compare the OL Switcher to the SYS, one has dual RCA in with a single RCA out, the other has Single RCA/3.5mm in with matching RCA/3.5mm out,

    aside from the different input/output configurations have we examined the two to see how differently they sound?
     
  18. Cspirou

    Cspirou They call me Sparky

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    Both use a 10k Alps pot. I highly doubt you’ll find any difference between them sonically. The OL switcher has an edge on features and price but they are basically the same product. I would base my decision entirely on looks.
     
  19. monacelli

    monacelli Friend

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    I use a SYS to switch back and forth between digital and my TT. I looked at the OL Switcher, but wasn't crazy about the slide switches they chose; they look a little chincy to me. Dual RCA inputs is also a big difference in my book. But I largely agree with @Cspirou. The SYS would tie in nicely with a Modi Multibit and a Magni 3, the OL Switcher not so much. They are both about as simple and passive as you can get, so I wouldn't expect any meaningful sonic differences. In my application, I basically can't tell the SYS is even in my chain.
     
  20. purr1n

    purr1n Desire for betterer is endless.

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    But but but the SYS... It can't possibly compare to the best preamps costing $5k+++ ... I mean Schiit makes stuffs which are great bargains, but not the best.

    How dare you say you can't tell when SYS is in the chain! Blasphemy! Obviously your gear or your DSDx512 recordings of monks fapping while chanting C at 256Hz aren't good enough for you to tell the difference.
     

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