Marrying Amp and Preamp (probably dumb question)

Discussion in 'Audio Hardware' started by Minty_fresh, Mar 14, 2018.

  1. Minty_fresh

    Minty_fresh Forum Resident Thread Starter

    Location:
    B.
    Though I wanted to go tubes on my next amp, I was researching the Schiit Freya/Vidar combo. The Freya scared me off but I got to thinking about different tubed line preamps i could use instead.

    I had read that a pre’s output impedance must be greater than the input impedance of the power amp. How important is this? Are there more important factors?

    For argument’s sake I’ve been pondering building an ANkit L2 Line stage (no phono) into a Schiit Vidar. This would be for a mostly vinyl system through a Lounge LCR MK3 spinning reggae, punk and some hard rock with a tiny bit of jazz. My aim is a balanced sound that can deliver bass extension, handle faster paced music and deliver warmth and articulate detail.

    Thanks.
     
  2. Old Audiophool

    Old Audiophool Well-Known Member

    Location:
    Melbourne, Fl.
    Why did the Freya scare you off?
     
  3. Minty_fresh

    Minty_fresh Forum Resident Thread Starter

    Location:
    B.
    Noise issues, stock tubes seem to be junk out of the box, people resorting to putting weight on the top to quell microphonics, socket rings, etc. sure they may have had a bad unit but I don’t have the kind of luck to assume I’ll get a good one.
     
  4. Old Audiophool

    Old Audiophool Well-Known Member

    Location:
    Melbourne, Fl.
    A friend has one, it sounds great, but he had a bad tube after about 3 weeks. He notified Schiit and they over nighted a full set of different tubes and all is well. Now that is good customer service. he had none of the other issues you wrote about. Enjoy.
     
  5. Minty_fresh

    Minty_fresh Forum Resident Thread Starter

    Location:
    B.
    There’s a few reviews on YouTube who had issues where tapping on the top of the chassis produced sound from the speakers while others fought radio interference. Others have had no issue. That the tube gain stage runs even if using passive or JFET mode is being used instead was disheartening but like I said, my luck has never been good in situations like this hence looking at other front ends to use with a Vidar.
     
  6. Benzion

    Benzion "Cogito, ergo sum" Forum Resident

    Location:
    Brooklyn, NY
    You got it reversed.

    "As a general rule, the lower the output impedance is, the better it will drive difficult loads. And, the higher the input impedance is the less difficult it is to drive. A good example of a happy situation is a preamp with an output impedance below 1000 ohms driving an amplifier with an input impedance of 100,000 ohms."
     
    R. Totale and Minty_fresh like this.
  7. Minty_fresh

    Minty_fresh Forum Resident Thread Starter

    Location:
    B.
    That’s correct. I read it completely wrong. I’m a bonehead.

    Outside of the impedances, what other factors should one look for when marrying a preamp and power amp?
     
  8. Benzion

    Benzion "Cogito, ergo sum" Forum Resident

    Location:
    Brooklyn, NY
    In my experience - noise levels.
     
  9. Minty_fresh

    Minty_fresh Forum Resident Thread Starter

    Location:
    B.
    So the Vidar has an input impedance if 22k ohms and the L2 line stage has an output impedance of 3k ohms. So this seems good on paper.
     
  10. Benzion

    Benzion "Cogito, ergo sum" Forum Resident

    Location:
    Brooklyn, NY
    Not too good, though. Ideally, you would want the input impedance of the power amp to be 10 times or more the output impedance of the line stage. In this case: 3k x 10 = 30k Ohm or more should be input impedance of the power amp for this line stage.
     
    Minty_fresh likes this.
  11. chervokas

    chervokas Forum Resident

    Well, yeah, in terms of minimizing voltage loss, 10X is the common rule of thumb, but it's not a line you can't cross. In practical reality 7+X -- as in the case of a 3K source impedance and a 22K load impedance -- probably would be perfectly fine, although a 3K output impedance is pretty high. I'd make sure to use the shortest reasonable length of interconnect between that preamp and any amp.
     
    hi_watt, Minty_fresh and Benzion like this.
  12. 33na3rd

    33na3rd Forum Resident

    Location:
    SW Washington, USA
    If you were considering Freya, you might look at Saga instead. Only one 6SN7 to feed, and it mates to Vidar really well. I love my Saga/Vidar combination.

    I didn't even try the stock tube, I have a box full of orphaned 6SN7's from past gear that needed matched pairs but managed to eat one up one of the pair before the other.

    Saga is really nice, and the price just makes it that much sweeter.
     
  13. Minty_fresh

    Minty_fresh Forum Resident Thread Starter

    Location:
    B.
    I looked at Saga and I feel like I would be cheating myself not to take this rare opportunity to buy the best I can afford. While I wouldn’t be using the Vidar in a monoblock set up I’d like to have that option.

    I’ve been reading up on the difference between a tube stage and a tube buffer and admittedly it’s not overly clear to me.

    Going with Vidar + Freya would be much cheaper then the integrated I am almost set on and would be a huge leap over my current amp. The Saga even more so.

    So I’ve been watching with interest. The thing is, I get 2-4 hours a week to spin a few sides and I don’t want to have to buy better feet, stack junk on top, buy tube rings and then have trashy noisy tubes because the installed ones aren’t remotely usable. Then have to diagnose weirdness and hum and noises....you get the idea.

    So that’s why I’ve been loosely looking at Vidar + a
    Different tube front end. While an ANK Kit would be over budget with the Vidar, it would be bought way ahead so I can build it and hopefully not burn this building down (ha). Then order Vidar.

    I’m open to considering any advice.

    I’d like to add that this process has been rough. My local Line Magnetic dealer refused to let me listen to a system as I was interested in the 216ia. I have never really been around tube amps to I wanted to see how it might work with my speakers playing the music I like vs what they play to impress people. The guy kept telling me “nah, you don’t want this” and basically I never got to hear it. Dude is also the local rogue dealer so for me to order either I have to do it used as dealers won’t sell to people with local dealers even if the local dealer is a pretentious ass.
     
    Last edited: Mar 14, 2018
  14. Old Audiophool

    Old Audiophool Well-Known Member

    Location:
    Melbourne, Fl.
    For a phono pre I would suggest the Musical Suroundings Phenoma II+, Music Direct has them for $750 with a 60day refund policy. It took about 50 hours for it to bloom, using it with my CA Maestro V2 cart, and it sounds fantastic. MM/MC loading available.
     
  15. Minty_fresh

    Minty_fresh Forum Resident Thread Starter

    Location:
    B.
    I’m looking for a line stage, not a phono stage. :)
     
  16. Old Audiophool

    Old Audiophool Well-Known Member

    Location:
    Melbourne, Fl.
    You said this was for spinning vinyl, mostly.
     
    Minty_fresh likes this.
  17. Mark broadhead

    Mark broadhead Well-Known Member

    Location:
    Newcastle England
    The ANK kits are excellent and great fun to build.
     
  18. Minty_fresh

    Minty_fresh Forum Resident Thread Starter

    Location:
    B.
    I have no experience but I read the entire instructions and it’s easy as it can be. I’ve heard they sound excellent.
     

Share This Page