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TL071 vs TL072

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  • TL071 vs TL072

    I know nothing about OpAmps, but I've seen a bunch of TL072's in amps before. But what about a TL071? Does it have more headroom?

    How do these OpAmps compare to 12AX7's and 12AT7's headroom wise?

  • #2
    Originally posted by leadfootdriver View Post
    I know nothing about OpAmps, but I've seen a bunch of TL072's in amps before. But what about a TL071? Does it have more headroom?

    How do these OpAmps compare to 12AX7's and 12AT7's headroom wise?
    A TL072 is two TL071's in the same package. TL074: four TL071's. Most op amps are operated off + and - 15 volt supplies, a total of 30V from rail to rail. Some you can sneak up a couple volts, say 36V rail to rail. So your max signal is a bit below 30V peak-to-peak.

    12AX7's & similar run from typically 120 to 250V on the plate - you can see how a much larger signal than anything available from a typical op amp and its power supply can be obtained, again depending on supply voltage, no contest, say from 4X to 10X more than op amps.
    This isn't the future I signed up for.

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    • #3
      Thanks, and wow... They don't even compare to tubes..

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      • #4
        Well, a TL071 compares to a TL072 the way a 6C4 compares to a 12AU7. Or comparing a 6AV6 to a 12AX7.
        Education is what you're left with after you have forgotten what you have learned.

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        • #5
          Headroom can be a fickle mistress. There are guitars that have too much output for a 12AX7 to handle without attenuation. And it's not just those active basses with the builtin 18V preamps. It's not how much output a device can create, it's how much input the device can handle before the output reaches it's maximum where it clips. That's where Voltage gain becomes part of the equation. So if the gain is kept low, a TL072 can have more headroom at it's input than a 12AX7. Most high end bass amps have an input stage made with opamps that has adjustable gain so the player can dial in as much headroom as needed. After EQ another gain control lets you adjust how much the output stage clips or how much headroom there is at the amps output.
          WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
          REMEMBER: Everybody knows that smokin' ain't allowed in school !

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          • #6
            That's cool.

            I just got an effects loop for my amp, and it has 2-TL071's. That's why I was asking. I was thinking an 071 was the ECC81 equivalent!

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            • #7
              Originally posted by leadfootdriver View Post
              I know nothing about OpAmps, but I've seen a bunch of TL072's in amps before. But what about a TL071? Does it have more headroom?

              How do these OpAmps compare to 12AX7's and 12AT7's headroom wise?
              Sorry, but your questions do not make sense.

              In fact, not sure you understand the meaning of headroom.
              Juan Manuel Fahey

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              • #8
                The headroom of an OpAmp is sufficient for an effective output voltage of about 10 V (+-14V peak to peak). You can drive a transistor (which needs to be capable of the current) without further voltage amplification to obtain 25W/4 Ohms.

                Tube circuits work differently: the signal voltages in the later stages are much larger, and the output is reduced through the output transformer.

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                • #9
                  Originally posted by leadfootdriver View Post
                  I know nothing about OpAmps, ...
                  This guy is fun to watch

                  https://youtu.be/7FYHt5XviKc
                  Building a better world (one tube amp at a time)

                  "I have never had to invoke a formula to fight oscillation in a guitar amp."- Enzo

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                  • #10
                    Originally posted by J M Fahey View Post
                    Sorry, but your questions do not make sense.

                    In fact, not sure you understand the meaning of headroom.

                    That's why I come here..

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                    • #11
                      Originally posted by tubeswell View Post
                      This guy is fun to watch

                      https://youtu.be/7FYHt5XviKc
                      Thanks. He's an Aussie dude.. lol

                      That' interesting that opamps were originally made for calculatio n s and not amplifying.
                      Last edited by leadfootdriver; 05-30-2016, 03:25 PM.

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                      • #12
                        Originally posted by leadfootdriver View Post
                        That' interesting that opamps were originally made for calculatio n s and not amplifying.
                        I took a class in hybrid computing in the '70s.
                        All I remember about it is that I took the class.
                        https://en.wikipedia.org/wiki/Hybrid_computer
                        DON'T FEED THE TROLLS!

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                        • #13
                          Originally posted by leadfootdriver View Post
                          Thanks. He's an Aussie dude.. lol

                          That' interesting that opamps were originally made for calculatio n s and not amplifying.
                          Well, amplification is actually a Math operation too, in this case *multiplying* some voltage value by a fixed amount.
                          We use them also in differentiation and integration, as in equalization and tone controls.
                          And more complex operations, as in active filters.
                          Also in addition and substraction, as in balanced inputs (we add useful signals, we substract unwanted noise).

                          So they are really at home inside amplifiers
                          Juan Manuel Fahey

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