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wound first pickup ...low output

Discussion in 'Pickups & Electronics [BG]' started by wilser, Jun 19, 2005.


  1. Hello,
    I just wound my first pickup. I used a single pole piece per string of alnico5. It measures 7.5kohm in my multimeter. Still the output is very low and fails to catch the string's vibration unless it's very close to the string (so close that it could cause the string to touch the poles if banged too hard). I used 43 AWG wound directly on the alnico pieces. Any idea why the output is so low?
     
  2. Jazz Ad

    Jazz Ad Mi la ré sol Gold Supporting Member Supporting Member

    Too many turns causing too high impedance I guess ?
    You can calculate this kind of thing.
     
  3. I'm curious; how did you wind it directly onto the magnets? Did you have any kind of bobbin to hold them in place?
     
  4. Audere

    Audere Supporting Member Commercial User

    Apr 7, 2005
    South Beach, OR
    Owner: Audere Audio
    Have you tested magnetic strength of the poles pieces?
     
  5. Jazz, impedance is at 7.5 kohm, which is about the same as a normal single coil jazz pickup and about the same as the bartolini 59J.

    Lemur, I made the bobbin by cutting the magnet rod to length and then CA gluing them directly to plastic pieces. The one on top with holes and the one on the bottom without them. It holds out pretty good. When I said directly into the magnet, I meant that I did not include any plastic or wooden isolation as some people do. But I've seen guitar single coils built this way, so why bother.

    Femtometric, the magnet's strength seems good. About the same pull I get from a P bass pickup I have with exposed pole pieces. Of course, this is judging by putting the tip of a pair of tweezers and measuring by feel. I have no instruments to scientifically measure magnet strength, but they seem fine.
     
  6. although i have nothing constructive to say at all, i must say congrats on making your 1st pickup, maybe on my next project ill do the same but i gotta get this one done 1st!

    were you trying to make a clone of the 59J? seems like your diggin the tone out of those just as much as i am ;)
     
  7. heh, no, not really. Those 59JCBs rock big time. They're the best sounding pickups I've heard. But I don't know the first thing about bartolini construction methods or materials. They're sealed in epoxy, so there's no way to know without totally destroying the pickup. I was just trying to make a single coil pair of pickups to use on one of my current projects. I wanted to get a normal J single coil sound, nothing fancy (at least on the first couple of pickups).

    Also, I just noticed that the coil is a little loose, I mean it's not very tensioned. Would that manifest itself as low volume?
     
  8. Audere

    Audere Supporting Member Commercial User

    Apr 7, 2005
    South Beach, OR
    Owner: Audere Audio
    When you state 7.5K ohms is normal you must consider that you are using 43 gauge wire. If the pickups you are comparing to might be using 42 gauge wire in which case the difference in turns would be about 1660/2140 (ohms of 1000' of both wires). The measurement of resistance started because measuring the number of turns was harder...

    Also check to make sure your winding path length is the same as the pickups you are comparing to. Some Barts are hum canceling by having 2 windings in parallel around 2 string poles each. This would increase the number of turns and output by 4X, but this would not apply to a single coil Jazz.

    Some meters have trouble measuring the resistance due to the large inductance. However in general, cheap meters work better than expensive bench meters because the auto range speed is much slower and the main cause of the problem. In addition if you measured the resistance with any noise sources around (especially think magnetic noise sources - i.e. motors) then you can get an incorrect reading because the pickup is generating a voltage source by picking up the magnetic field which will cause the meter to generate a bad result.

    Winding directly onto the magnetic works fine. Plastic is a valid spacer.

    I assume this is a straight pole piece design and you have non magnetic material around you testing area. This would be an easy way to get faked out.

    What are you measuring the output with? I.E. what are you connected to and what is it’s input impedance.

    When you test the resistance do you test it with the same wires connected to the pickup you use to test the output?

    Not required - but for your future reference, you could improve your magnetic testing slightly with a spring stretch measurement. Think of a small scale of some sort where you would normally hang the object to be weighed off the bottom of the scale. Add a steel slug to the bottom and measure break away pull. Good for cheap relative testing.

    Loose winding should not change it too much.
     
  9. fem,
    thanks a lot! this provides plenty of information. There are no magnetic sources around other than a desk lamp. I am measuring with a relatively cheap ($40) digital multmeter (extech). I am testing the output by installing on a bass. I have not installed a counter on my winder, so I just tried to 'estimate' by knowing the RPMs and then measuring time while winding (I know, neanderthal methods, but until I have a counter, this is it).

    I'm gonna try winding more turns on the next pickup, see if that makes a difference and I can stop blaming materials.

    thanks again.
     
  10. Audere

    Audere Supporting Member Commercial User

    Apr 7, 2005
    South Beach, OR
    Owner: Audere Audio
    Some desk lamps - like halogens use a transformer to lower the voltage.

    My shop is near a high voltage power line and I get lots of noise pickup some days but not others.

    But you can use your meter to measure the AC output from the coil without the string vibrating. Zero output voltage would indicate no external noise sources are generating voltages to cause your resistance measurements to be off.

    RPM x Time (in minutes) works...

    You might try winding a 1 string pickup till you get it the way you like it. A couple of plastic washers glued on to the magnet is easy to work with and saves time and materials.
     
  11. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    I can't remember who's got what. Do you have that Lawrence (whoever it is) guide to making pickups? I've haven't read through all of it but what little I've read is pretty step by step and seems pointed out some ramifications if you didn't do certain things. At any rate, from what I gathered, if you followed the steps with any accuracy, I would be suprised at such results.

    Pups appear simple in nature but there are so many variables that affect results. I've never attempted to make a pup and my understanding of what goes into them to produce given results is minimal, but logically the output should be reflected by the DC resistance. There is issue with the strength of the magnetics and inter-relationship of the poles. I recently read a piece regarding never forcing opposite poles of alnico 5 magnets together or it will weaken them.
     
  12. i found the perfect pickup wind counter made out of a calculator and a magnet, i dont remember where it is though, i have t bookmarked on the other computor so ill see if i can find it, i cant find it via google at the moment
     
  13. Audiophage

    Audiophage

    Jan 9, 2005
    Where can I find this guide?
     
  14. Yes, I read that page, but there's a limitation about speed. My winder goes up to 3500rpms (it is a variable speed sewing machine motor, via pedal control), but I generally run it at less than half that. The calculator counter is limited to less than 100 per sec. so it's no use to me. I made a winder years ago (but I never made a pickup with it) using pieces from an old printer. I also made a computer interface and coded a unix program using the QT toolkit. I also built a power control. So you could actually set the number of turns on the computer program, hit a key on the keyboard to start the motor and when the turns reached the threshold the motor was stopped automatically. Worked great, but I had to dismantle it and everything got lost when I moved. I'm thinking of revisiting the logic control on this new machine. Maybe even logic control variable speed?

    luknfur
    I can't remember who's got what. Do you have that Lawrence (whoever it is) guide to making pickups? I've haven't read through all of it but what little I've read is pretty step by step and seems pointed out some ramifications if you didn't do certain things. At any rate, from what I gathered, if you followed the steps with any accuracy, I would be suprised at such results.

    Actually, I'm not following any guide. I have no documentation whatsoever, and I am going by what I have read on a few websites (they really have no details). I would really like to get my hands on a book with theory on pickup design and building. I have not been able to find one ...anybody have recommendations? What's that Lawrence book?
     
  15. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    I'll forward it to you next time I have the downtime and am around the computer.

    I only have half the book which is information on actually windng pickups. The first half on winders I don't have cause I have no intereset in winding my own so didn't want it. Unfortunate for you cause it sounds like you could use it and there were I think different winders listed in the book and details on making them. The book has recently gone out of print and is no longer available.
     
  16. Audere

    Audere Supporting Member Commercial User

    Apr 7, 2005
    South Beach, OR
    Owner: Audere Audio
    Lawrence or is that Lollar as in ISBN 0-9662599-2-0
    Basic Pickup Winding and Complete Guilde to Making Your Own Pickup Winder
     
  17. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    Probably is Lollar, they all run together to me. At any rate, last check the book was listed on the site but was out of print as of about January and there are no known copies availalbe for sale from retailers. Oddly enough, even the source doesn't have an original copy they could copy.
     
  18. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
     
  19. yeah, I have emailed them and a couple of stores and there seems to be none available. I am not interested in the winder part, as I already built one. I am interested in the actual pickup construction part. I'll shoot you an email.

    Thanks!
    Wilser.