Announcement

Collapse
No announcement yet.

When do you NEED a preamp?

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • When do you NEED a preamp?

    I am looking at a tube amp that has Input Sensitivity: 810mV, Input Impedance: 100k Ohms. I would like to use a passive preamp that I have but I am wondering if that will be OK. Since I used my iPhone for streaming I may need a pre/dac for that but I am not sure.

  • #2
    You'll need the preamp unless your source has a volume control of its own.

    So, if you're plugging your phone into the amp with a minijack cable, you can just use your phone and ignore the preamp.
    R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

    Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51


    95% of Climate Models Agree: The Observations Must be Wrong
    "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

    Comment


    • #3
      Originally posted by stephenmarklay View Post
      I am looking at a tube amp that has Input Sensitivity: 810mV, Input Impedance: 100k Ohms. I would like to use a passive preamp that I have but I am wondering if that will be OK. Since I used my iPhone for streaming I may need a pre/dac for that but I am not sure.
      A passive preamp will only provide attenuation, no gain.

      Comment


      • #4

        Comment


        • #5
          100k is a nice high input impedance. So long as your source has an adequate output voltage (2v or more) I think you would be fine with a passive unit, so long as the input impedance of the passive pre stays higher than the output of the source and the output impedance of the pre stays less than the input of the amp. My understanding of passive preamps is the impedance of the pot can roll off hf response if too high, and also allow noise. My knowledge of this is very limited and I’m sure someone else can correct my misunderstanding of the subject. I say try it with what you have for a preamp and if you like it call it good.

          Not to derail your thread but what amp are you looking at?
          Projects:

          Breezy Monitors: http://techtalk.parts-express.com/fo...reezy-monitors
          transcenD: http://techtalk.parts-express.com/fo...5035-transcend
          Summits: http://techtalk.parts-express.com/sh...75-The-Summits
          References: http://techtalk.parts-express.com/sh...-My-References
          Vintage Style 2-way: http://techtalk.parts-express.com/sh...-vintage-2-way

          Comment


          • #6
            Originally posted by dynamo View Post
            100k is a nice high input impedance. So long as your source has an adequate output voltage (2v or more) I think you would be fine with a passive unit, so long as the input impedance of the passive pre stays higher than the output of the source and the output impedance of the pre stays less than the input of the amp. My understanding of passive preamps is the impedance of the pot can roll off hf response if too high, and also allow noise. My knowledge of this is very limited and I’m sure someone else can correct my misunderstanding of the subject. I say try it with what you have for a preamp and if you like it call it good.

            Not to derail your thread but what amp are you looking at?
            Thank you. I am looking at the PrimaLuna Prologue 5. This is a slightly older tube amplifier. http://www.primaluna-usa.com/prologue-five/

            Comment


            • #7
              Originally posted by stephenmarklay View Post
              ... can I get away using this “volume control -passive”? I would like an active but if I buy the amp I won’t be able to swing a proper active preamp.
              I use a "passive" in my Tri-amped Active system without problems ( power is ample and speakers are high sensitivity )
              Use a calibrated signal and measuring AC voltage to get numbers

              "Not a Speaker Designer - Not even on the Internet"
              “Pride is your greatest enemy, humility is your greatest friend.”
              "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

              Comment


              • #8
                I think they are nice used amps for the money as far as commercial goes. The pic in my avatar is my Prologue Four. I like it. Plenty of output for 35wpc. It is dual purpose for now so it also sees some HT use with no issues. I currently have it stuffed with RCA black plates up front and TungSol el34b power tubes. Easy to use, maintenance free, and easy on tubes (all the stock tubes came with it and still work fine)

                I bought a tube preamp because I wanted to play with one, but ran it just fine for quite a while with a schiit sys passive pre, driven by the dac’s built in preouts (MF V90dac). I definitely didn’t need the active preamp. I believe the schiit passive has a 10k pot.
                Projects:

                Breezy Monitors: http://techtalk.parts-express.com/fo...reezy-monitors
                transcenD: http://techtalk.parts-express.com/fo...5035-transcend
                Summits: http://techtalk.parts-express.com/sh...75-The-Summits
                References: http://techtalk.parts-express.com/sh...-My-References
                Vintage Style 2-way: http://techtalk.parts-express.com/sh...-vintage-2-way

                Comment


                • #9
                  Originally posted by dynamo View Post
                  I think they are nice used amps for the money as far as commercial goes. The pic in my avatar is my Prologue Four. I like it. Plenty of output for 35wpc. It is dual purpose for now so it also sees some HT use with no issues. I currently have it stuffed with RCA black plates up front and TungSol el34b power tubes. Easy to use, maintenance free, and easy on tubes (all the stock tubes came with it and still work fine)

                  I bought a tube preamp because I wanted to play with one, but ran it just fine for quite a while with a schiit sys passive pre, driven by the dac’s built in preouts (MF V90dac). I definitely didn’t need the active preamp. I believe the schiit passive has a 10k pot.
                  Wow! I could have asked for a more appropriate response! I am actually in between the 4 and 5 but for the cost difference which is not a ton I think I will go with the 5. I can always use an El34 later.

                  Comment


                  • #10
                    Have you thought about this one?

                    Comment

                    Working...
                    X