Ad Widget

Collapse

Announcement

Collapse
No announcement yet.

Bigger Wire, Less Turns

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

  • Bigger Wire, Less Turns

    I need to build a pickup for an active circuit, P bass design. What size wire and turn count would you use. I have a set of bobbins with 1/4" magnets, and a set with 3/16" magnets. I will probably do them both, just wondering what to start with anyway. How would, or how do, you build them?
    Thanks
    Ron
    It's just wire wrapped around some magnets!

  • #2
    Originally posted by gilligan View Post
    I need to build a pickup for an active circuit, P bass design. What size wire and turn count would you use. I have a set of bobbins with 1/4" magnets, and a set with 3/16" magnets. I will probably do them both, just wondering what to start with anyway. How would, or how do, you build them?
    We need a bit more information. Tell us more about the active circuit. What input voltage does it need, for instance. And its input impedance.

    Comment


    • #3
      It is the two band , 4 control, version from Guitar Jones, for bass. I will see what I can find out about it.
      Ron
      It's just wire wrapped around some magnets!

      Comment


      • #4
        If you are looking to make a low impedance pickup... You can make an Alembic clone pickup... use 40 ga wire and wind about 1500 turns on each bobbin.

        You can go with smaller gauges too... use 42 or 43 gauge for lo-z pickups.

        The first P bass pickups I made this way had about 500~1000 turns of 42 on each bobbin.

        Does this active circuit work with low output pickups? You may need a buffer between the pickup and the preamp.
        It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein


        http://coneyislandguitars.com
        www.soundcloud.com/davidravenmoon

        Comment


        • #5
          Thanks David. I don't know if it works with low output pickups? Something I probably need to know! I've never used, or repaired, a guitar with active electronics. I guess I thought they all had low output pickups? Although I know some can be switched to passive if the battery fails. Trying to find out about this one I have.
          Ron
          It's just wire wrapped around some magnets!

          Comment


          • #6
            Originally posted by David Schwab View Post
            If you are looking to make a low impedance pickup... You can make an Alembic clone pickup... use 40 ga wire and wind about 1500 turns on each bobbin.

            You can go with smaller gauges too... use 42 or 43 gauge for lo-z pickups.

            The first P bass pickups I made this way had about 500~1000 turns of 42 on each bobbin.

            Does this active circuit work with low output pickups? You may need a buffer between the pickup and the preamp.
            Hi David, forgive me for sounding dumb but can you explain Low Z pickups?? I have heard the term lots but never knew what it meant. Thanks.

            Comment


            • #7
              The fact o the matter is that there is no use for low Z bass pickups. All aftermarket bass preamps are intended to connect to normal, passive high-z pickups. Or a few are intended to connect to Active pickups which have a built-in buffer circuit.
              Last edited by David King; 05-02-2007, 02:00 AM. Reason: no reason, why are you all so suspicious?

              Comment


              • #8
                Here's the specs I found.
                So I just use a typical wind!
                Thanks,
                Ron
                It's just wire wrapped around some magnets!

                Comment


                • #9
                  Oops

                  Specs: RBA04 2 Band E.Q
                  Master volume : A30K
                  Balance : MN250K
                  Treble and Bass : B30K
                  Control range : 40Hz~15Khz
                  Treble control:300Hz~15Khz
                  Bass control : 40Hz~500Hz
                  Frequency respones : 20Hz~20KHz

                  May not be enough though.
                  Ron
                  It's just wire wrapped around some magnets!

                  Comment


                  • #10
                    Don't get low z and low v mixed up. Some pickups have a surprisingly high v for such a low z. Z is sort of relative when it comes to pickups. Relative to Freq - if you get my drift. If you go with low output (ie low v) pickups and they are blended passively (ie prior to the pre- as a 250k blend pot would suggest) you could run into some problems. So as David said, you should probably buffer these before they are blended - in which case, you should probably also throw the vol in before the main pre and use a smaller value blender pot (if you can find one! - I make my own). If the pickups are really low output (like a pair of bartolini J's that I came across recently), a pair of buffer pre's that have a little gain might be the way to go - in the interests of gain structure. (Although gain is very over-rated for onboard bass pre's - but that's another thread...)

                    Comment


                    • #11
                      Originally posted by David King View Post
                      The fact o the matter is that there is no use for low Z bass pickups. All aftermarket bass preamps are intended to connect to normal, passive high-z pickups. Or a few are intended to connect to Active pickups which have a built-in buffer circuit.
                      Gee David, I wouldn't say all that! Some active pickups are low Z, like the Duncan units. Even their passive pickups are fairly low impedance... I just installed a set of 5 string MM pickups for someone, and they were only 4K. Some Barts are also medium impedance, as were the Lane Poor pickups. The Jack Cassidy/LP Signature bass has low Z pickups. And of course Alembic pickups are low Z. Q-Tuner also make medium Z pickups.

                      I'll agree about after market preamps being made for high Z pickups.. that's true. But Low Z pickups have much wider and flatter frequency response than High Z pickups.

                      I use commercial preamps, but I buffer my pickups first.
                      It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein


                      http://coneyislandguitars.com
                      www.soundcloud.com/davidravenmoon

                      Comment


                      • #12
                        Originally posted by madialex View Post
                        Hi David, forgive me for sounding dumb but can you explain Low Z pickups?? I have heard the term lots but never knew what it meant. Thanks.
                        Let's take an example.. a Duncan SJB-1 vintage Jazz Bass pickup. It's 9.2 to 9.5K. The hot version is 15-16K. A P Bass is about 11K. Now an Alembic series I pickup is about 2K, and wound with 40ga wire, which gives you a lower resistance coil.

                        Impedance (Z) is defined as "the effective resistance of an electric circuit or component to alternating current, arising from the combined effects of ohmic resistance and reactance." The thing to keep in mind is the impedance of a pickup increases with frequency. You can also use AC resistance, since the two are fairly analogous. So as the impedance increases, you get a resonant peak and high end roll off starting at a lower frequency. You also get less low end. You can see another example with microphones. No one would use a high Z mic for anything where accurate sound is required!

                        Think of the word impede; "a hindrance or obstruction". So with more windings we get more output, but also a narrower frequency band, starting with the loss of high end. We've all heard that with very hot humbuckers. A Gibson EB-O sidewinder is a great example... around 22K and almost no high end at all.

                        The problem with low impedance pickups is that amplifiers (and the rest of the signal chain) are made for high impedance pickups. So just as with Low Z microphones, you need to step the level up, either with a transformer or preamp.

                        There's nothing wrong with high Z pickups, and we are all accustomed to their tone. But if you want a really wide, smooth, and flat reproduction of the instrument with little coloration, low Z is the way to go.

                        An easy test is to wind 1000 turns of wire on each bobbin of a P bass pickup, and run that through a FET buffer. The frequency response will be extended in both directions. Glassy smooth highs and a low end that goes WAY down low. The first time I tried this was on an 8-string bass I made that originally had 2 DiMarzio Model P pickups in it (there wasn't a big pickup aftermarket back then). The bass was harsh sounding with weak low end before the rewind. With the low Z pickups it sounded like a totally different bass.

                        Thinking about that tone I got is what got me back into making pickups again. I just wasn't hearing what my basses really sounded like with the EMG's I had in them.

                        Check out the samples here to hear some low Z bass humbuckers.
                        It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein


                        http://coneyislandguitars.com
                        www.soundcloud.com/davidravenmoon

                        Comment


                        • #13
                          David, I would tend to define low-Z pickups as anything below 200 ohms. I'd set mid -Z, if such a term existed, from 200- 600 ohms.
                          2k would qualify as high-z in my experience. I realize that's never been stated categorically in any bass book but pro-audio norms are pretty well defined here.

                          Buffers are good but they cause no end of hardship if you ever want to run in passive mode.

                          Comment


                          • #14
                            Originally posted by David King View Post
                            David, I would tend to define low-Z pickups as anything below 200 ohms. I'd set mid -Z, if such a term existed, from 200- 600 ohms.
                            2k would qualify as high-z in my experience. I realize that's never been stated categorically in any bass book but pro-audio norms are pretty well defined here.
                            That's true. When talking about microphones, etc. low Z is low... Pickups are much higher of course. I'm defining low impedance pickups by what was done by Les Paul, Alembic, etc. I guess it's all relative to what you are plugging them into. Piezo pickups are very high Z.

                            Originally posted by David King View Post
                            Buffers are good but they cause no end of hardship if you ever want to run in passive mode.
                            The way I look at it is the pickups don't work in passive mode, and there's no advantage to doing so. Why would you want to? Think of active pickups. You can't run them in passive mode, and the advantages they might have over totally passive pickups requires them to have a buffer. If someone wants that sound, they are aware that they need to have the instrument powered from some source... I don't think anyone who buys an active only bass has a problem with it never being passive, just as they aren't acoustic either. We always have to plug an "electric" instrument into something.

                            Now on the other hand there's nothing that says that the first gain stage has to be in the bass. I was trouble shooting a new pickup/buffer design the other day, and to verify that the pickup was working (because the buffer wasn't) I ran the output right to the jack and into my Behringer mixer. All I had to do was give it some gain at the mic preamp. At 4K the pickup was still higher Z than the preamp works best with, but it works and sounded fine.

                            It's the same with tone controls... when you want to go beyond what you can get passively, you need to go active. I have some passive guitars, but all my basses are active.
                            It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein


                            http://coneyislandguitars.com
                            www.soundcloud.com/davidravenmoon

                            Comment


                            • #15
                              O.k.

                              As I stated, this is my first experience with active circuits, soooo... I have an active setup from Guitar Jones. It looks like it has everything there except the pickups. ( mast vol., treb., bass, balance controls ) So you are saying that this was built for passive pickups, and in order to use low z pickups, I need to buffer them? Is this something that I can buy, or do I build the buffers? I want the benefits of low z, so I guess I need to do some reading up!
                              Thanks,
                              Ron
                              It's just wire wrapped around some magnets!

                              Comment

                              Working...
                              X