psw Posted July 29, 2008 Report Share Posted July 29, 2008 The cover acts as a shorted turn, so it lowers the inductance and lowers the Q of the resonant peak somewhat. Because it's non-magnetic metal, it doesn't have any effect on the magnetic circuit that would increase the inductance. The rule is that non-ferrous metals lower the inductance and ferrous ones increase it. Interesting...very interesting! I still don't hear a lot of difference but if the cover is built as an integral part of the design, or my idea of aluminium bobbins for instance, doesn't sound as crazy as it seems as long as the sum of the design takes that into consideration. Ferrous covers will add to the inductance I can see but may also diminish the effectiveness of the field with most of it going through the cover and never getting to the strings. I have never heard of any magnetic pickup covers... pete Oh...and back off topic...on the fender full range HB's...was doing a little work on mine and took some pics... Now that's a pickup cover. Notice that the pickup is considerably bigger than a gibson style HB. In order to mount it I needed to make a pickup surround from aluminium sheet. On the back you can see the size of the screw magnets and how they protrude on the blind poles more out the back of the pickup. Also, note how much the pickup base is sunk into the cover, the pickup is very shallow and not just because the magnets are in the poles. The coils would appear to be broader and thinner almost like a pair of P-90s. Quote Link to comment Share on other sites More sharing options...
kpcrash Posted July 29, 2008 Report Share Posted July 29, 2008 Very interesting - so if a non-ferrous cover would alter the Q by lowering inductance and (as psw and I are discussing in another post) we can totally control resistance (maybe not effective resistance) through pickup construction and circuitry would it be fair to say that pickup covers "could" impact overall tonal quality - showing a more dramatic effect with resistance that is managed away from the magnetic field? May sound crazy - but just a thought that I'm still piecing in my head right now. If this were true, could we then use the cover to spread the magnetic field? Could it then be directionally grounded to prevent microphonics? Would it matter? Again - just thoughts. My flame shield is up. Quote Link to comment Share on other sites More sharing options...
IWishICouldShred Posted July 29, 2008 Report Share Posted July 29, 2008 (edited) kp, were you suggesting carbon fiber pickup covers earlier? Cause that would be awesome. Great thread by the way. I was kind of wondering about this myself... everyone knows the DiMarzio zebra bobbin story, but the part about why people started taking the covers off is always kind of ambiguous Edited July 29, 2008 by IWishICouldShred Quote Link to comment Share on other sites More sharing options...
psw Posted July 29, 2008 Report Share Posted July 29, 2008 Very interesting - so if a non-ferrous cover would alter the Q by lowering inductance and (as psw and I are discussing in another post) we can totally control resistance (maybe not effective resistance) through pickup construction and circuitry would it be fair to say that pickup covers "could" impact overall tonal quality - showing a more dramatic effect with resistance that is managed away from the magnetic field? May sound crazy - but just a thought that I'm still piecing in my head right now. If this were true, could we then use the cover to spread the magnetic field? Could it then be directionally grounded to prevent microphonics? Would it matter? Again - just thoughts. My flame shield is up. Sorry no flames...but I am not sure I follow..perhaps a bit tired. Microphonics are usually cused by loose windings, or loose anything really, often covers. Controlling them is a potting issue. This thread seems to indicate that covers do make a difference but it is generally subtle (judging from my before and after hearing from taking covers off). On some designs, like a tele neck pickup it may make more of an impact than others and it may just be all that chrome, but I suspect that the cover on my above pictured FRHB makes a difference to the tone...certainly adds to the mojo effect! It would seem that pickup covers might be an overlooked area of exploration for custom pickup makers. How about this for lack of covers...a new gibson goddess Clear bobbins so you can see the wire and you know it is going to sound good! As I can't resist spreading the sustainer love, my latest driver takes this even further... No cover...no bobbins, just magnets, steel core and wire held together by epoxy...the ultimut in potting and minimalist construction. This one is designed to surface mount next to the SCN neck pickup in the background. Compact pickups could also be constructed in a similar manner I guess...you could stick them on where ever you want, as many as you want, all without a router!!!! hehehehehehehe... It is interesting though, a lot of common "theory" says things are "bad" like metal bobbins but if they are used or designed in for an effect, I guess they could work to some advantage in the right design. Great thread by the way. Yes...this is a cool thread...I forget who started it and more than once the topic pete Quote Link to comment Share on other sites More sharing options...
heggis Posted July 29, 2008 Report Share Posted July 29, 2008 I believe that the Gibson Goddess actually has covers, but they are clear acrylic or similar. I did the same thing with my prototype sustainer. I really like the look of pickups where you can see the coils! (However my sustainer looked like it fell out of the ugly-tree, oh well) Heggis Quote Link to comment Share on other sites More sharing options...
SwedishLuthier Posted July 29, 2008 Report Share Posted July 29, 2008 Ferrous covers will add to the inductance I can see but may also diminish the effectiveness of the field with most of it going through the cover and never getting to the strings. I have never heard of any magnetic pickup covers... That’s the reason we have never seen a ferrous cover. The flux will go through the cover and the pickup will be more or less dead. Early on in my pickup making days (not too long ago) I made the mistake of using a ferrous base plate for a P90 style pickup. I had experimented with using/not using the ferrous base plate for Tele neck pickup, had used the same idea for Strat style pickups and wanted to see what it would do for a P90. It more or less shortened the magnets of the P90 pickup and all I got was a hissing sound. Great pictures of the Fender bucker. I would love to have the bobbin dimensions if you some day decides to take the covers of. Quote Link to comment Share on other sites More sharing options...
psw Posted July 29, 2008 Report Share Posted July 29, 2008 I really like the look of pickups where you can see the coils! (However my sustainer looked like it fell out of the ugly-tree, oh well) hahahaha...LOL ROFL!!!! It is a hazard....the secret is not to post the ugly ones...check this out... that really was funny, thank you, going to bed with a smile on my face over that!!! hahahahaha I got hundreds of bastard children!!! The first box is just the latest design rejects that I had to go through to get this kind of epoxy winding without bobbins down. I notice at the bottom of the second one is an aluminium bobbin from my ball bearing pole piece design I described earlier in this thread. Notice the cool ventilation holes...hehehehe! Imagine the eddy currents in this design...the whole thing is non-ferrous metal....hahhahha. You got to admit though it would look cool, like the Harley Davidson of pickups! Major Mojo! Ok...back off topic... It is an amazing pickup and I am tempted to hack into it. Somewhere I found a picture of one opened up and it looked as if the entire cover was back filled with wax! I also found out that some people are spending $800 US a piece for them However, it is tempting to lift the lid on it as the original shielded cable is a little weird, but I guess this might depreciate it if I were to alter it. There is a lot more to this pickup than the coils though, I could do some approximate measurements of the cover to get a rough idea as the coils fully fill it from other pictures. The poles are way oversized and of course magnetized and so the core of the coil is going to be bigger than normal. The bobbins seem to be a bit flatter than a standard HB but also wider and the overall tone is very bright...think mid-era classic rolling stones sound. I would think you could get something good happening by stealing some of these tricks for a standard sized bucker. Remember this will not fit into any standard pickup hole in any direction! For inspiration though, a standard HB but with strat mag poles three a side and screw poles in the other three with perhaps some under bobbin side coils in ceramic would make an interesting mix. The designer really knew his stuff as it has an undeniable "fender" sound but is far from the single coil design as you could get. If I can remember where I saw the pics of the inside, I will get them for you! In another thread elsewhere in the forum on active pickups, I raised the notion of alternate active solutions, and I am tempted to do a bit of pickup design at some point. It would be interesting to see what you could come up with in low impedance pickups compensated for by active circuitry as an alternative to EMG. Desperately trying to circle back on topic... I wonder if in low powered, low impedance active boosted designs whether the effects of covers would be more apparent? pete Quote Link to comment Share on other sites More sharing options...
WezV Posted July 29, 2008 Report Share Posted July 29, 2008 It is an amazing pickup and I am tempted to hack into it. Somewhere I found a picture of one opened up and it looked as if the entire cover was back filled with wax! I also found out that some people are spending $800 US a piece for them the reissues use normal sized humbucker bobbins and a hell of a lot of wax.. the originals had larger bobbins that fit properly lots of info and pics on the TDPRI http://www.tdpri.com/forum/just-pickups/10...humbuckers.html Quote Link to comment Share on other sites More sharing options...
psw Posted July 29, 2008 Report Share Posted July 29, 2008 Ahhh...that is exactly where I saw it and this thread proposing recreating the original was very interesting and shows the interest in these elusive pickups. Of course, in their day they were much maligned and I may be perpetuating the mojo about them, so try and disregard that... See, I saw that pic and I was too scared to take mine apart, but now I see that this is a great comparison of what an original looks like vs. the modern reissue...completely different... The top one with the wax is actually the new reissue, basically a standard HB in a WRHB cover of sorts. Guitar fetish have an standard sized look-a-like HB with offset poles and plain cover (actually, artec ) which might have some of it's character. You can kind of see the difference in size of the coils, further apart, flatter and bigger pole pieces. All the wax filler in the new one is taken up with pickup in the original. All mojo aside, it just goes to show what can be done if someone steps out of the box in terms of pickup size and style to create something special and different. Practically though, it wont fit into a standard hole so it is no replacement unit! What it tells me is there are other forms of inspiration over the standard HB and SC formats. It is even possible to tip the coil on it's side...this is a feature of the infamous q-tuner pickups from the "animal magnetism" book guy (an odd one that) with heaps of mojo claims attached...(as I recall the side wound pickups didn't work out so well in his original test projects compared to more conventional designs) Got to love the look of those coils, rare earth so you know it's, errr rare... and 36 poles on this one...say no more. I heard a whisper that the epoxy is prone to cracking, but full marks for thinking outside the box!!! Try and find a cover to fit one of these if you dare!!! Looks like he has significantly updated the designs since last I looked...even a strat sized one...they look like jewelry. In fact, I am incredibly impressed, I wonder how he is able to wind these things as they appear to have no bobbins at all and I don't think I could get that crystal look...there,s not a bubble in sight!!! Ruthlessly accurate wideband sound Does this mean they have no soul? Are these truely the first neomag pickups. The side coil was used in the old gibson grabber basses as I recall. Still they are pretty and I see the prices are more than reasonable ($125-150)... Any pickup aficionados what to hazard a guess as to how they could be wound? pete Quote Link to comment Share on other sites More sharing options...
kpcrash Posted July 29, 2008 Report Share Posted July 29, 2008 I wonder if in low powered, low impedance active boosted designs whether the effects of covers would be more apparent? I guess this was my question exactly - just couldn't get it out quite that clear. Quote Link to comment Share on other sites More sharing options...
Robert_the_damned Posted July 29, 2008 Report Share Posted July 29, 2008 Are these truely the first neomag pickups. well the first production ones I'd say..... bit more high tech than the pickups neodymium I made about two and a bit years ago! I wonder if in low powered, low impedance active boosted designs whether the effects of covers would be more apparent? I guess this was my question exactly - just couldn't get it out quite that clear. I'd suggest maybe not, as the active part will compensate for any reduced output due to additional distance. Hell a low powered low impedance active boosted system is basically what an EMG is. Any pickup will have reduced output due to distance but if you've got a greater than unity amplifier afterwards it'll help reduce any lack of output due to pickups being far from the strings. Quote Link to comment Share on other sites More sharing options...
psw Posted July 29, 2008 Report Share Posted July 29, 2008 I'd suggest maybe not, as the active part will compensate for any reduced output due to additional distance. Hell a low powered low impedance active boosted system is basically what an EMG is. Any pickup will have reduced output due to distance but if you've got a greater than unity amplifier afterwards it'll help reduce any lack of output due to pickups being far from the strings. You can compensate electronically for a lot of things but less windings and magnet strength and inductance will have dramatic effects on the resonant frequency (the Q factor) and so the tone of a pickup. As we have discussed here, the covers appear to have some effect on this through the effects of eddy currents, even kill it completely with ferrous metals . The real thing about the Q-tuner is the adjust-ability of the pickup which is very clever... http://www.q-tuner.com/adjust.shtml You can see with the magnets mounted across the pickup that the poles can be adjusted so that some are facing the strings and some aim directly away. How much of an effect this has is up for debate...it might be as subtle tone wise as a cover or not. The "air coil" thing is a bit of a furphy in that it appears not to have bobbins, but the whole epoxy thing is effectively a giant bobbin...not that it matters much. They look great but if you adjusted these poles too much I fear the epoxy will crack and scratch up significantly. I wonder if in low powered, low impedance active boosted designs whether the effects of covers would be more apparent? I guess this was my question exactly - just couldn't get it out quite that clear. So, the question still stands... pete Quote Link to comment Share on other sites More sharing options...
SwedishLuthier Posted July 29, 2008 Report Share Posted July 29, 2008 Thanks for the Fender bucker pic Pete. That was an awful lot of wax in there... All mojo aside, it just goes to show what can be done if someone steps out of the box in terms of pickup size and style to create something special and different. See, that’s why I’m collecting data about “odd” pickups. To be able to expand beyond the more traditional designs. Quote Link to comment Share on other sites More sharing options...
WezV Posted July 29, 2008 Report Share Posted July 29, 2008 Thanks for the Fender bucker pic Pete. erm... its alright, but my names not pete Quote Link to comment Share on other sites More sharing options...
psw Posted July 29, 2008 Report Share Posted July 29, 2008 Thanks for the Fender bucker pic Pete. erm... its alright, but my names not pete See the power of the image, you do the hard yards to find the thread...I posted the picture!!! If you like we could change names, I named my son wes pete not wes Quote Link to comment Share on other sites More sharing options...
psw Posted July 29, 2008 Report Share Posted July 29, 2008 All mojo aside, it just goes to show what can be done if someone steps out of the box in terms of pickup size and style to create something special and different. See, that’s why I’m collecting data about “odd” pickups. To be able to expand beyond the more traditional designs. Yes, I can see that and since you are more likely to actually do it than I am more than happy to lend a hand. Eventually we may see magnetic pickups go completely for piezo modeling like line 6 you know...but for now~ I would encourage you to consider the heavily mojo influenced vintage classics like the FWRHB. On this guitar I am working on the big surprise was the tele SCN pickup. This uses side mid solarium colbolt magnets that seem to have considerable strength to focus the field and separate the stacked coils. It is a compact pickup, but boy does it have a warm creamy sound to it. I also liked the similar JB noiseless designs. I think lawrence had a big hand in both of these. Lace has created some really off the wall ideas (there are numerous makers in the Lace family) and many of these ideas can be found in the patents. Alumitones are just one of a number of wierd approches they have thought up over the years. Of course I am biased/obsessed...but the idea of a pickup sustainer driver has been something that I have been pushing for years... It recently came into being to an extent with the new moog guitar (I wonder if they had read the thread~) Another interesting thread that has been referred to is this discussion on active pickups... http://projectguitar.ibforums.com/index.ph...mp;#entry387117 I have been thinking that this kind of thing opens up more doors to a pickup designer. The question should arise as to what the intention is in a design. If you want a classic rock tone, we know how to get it and the classic designs are the easiest way to achieve it. If you want to get character and variation then playing with these (over winding, magnet structure, covers, etc) is probably the way to go. If you want something different, then look at some of the secoond tier classics like the filtertron and lipstick. EMG's are a classic sound to I would suggest. Novelty for novelties sake is a little much. How often do you hear people wanting to create clessic sounds by novel means...it seems to miss the point. The FWRHB is impressive because the designer set out to create a fender sound from an HB and achieved it. It did not come out as a strat sound in an HB format or anything, but it did capture the essence of the "fender sound" without falling into mimicry. But we all like a little novelty and mojo now and again. I'd like to build an HB format pickup with one side coil and one normal coil for instance...just cause I like the idea of the thing! pete Quote Link to comment Share on other sites More sharing options...
foil1more Posted August 2, 2008 Report Share Posted August 2, 2008 Oops, screw up. Yeah ferrous metals can effect. If can be picked up by a magnet, it can probably be made magnetic and that will affect the magnetic field of the pickups. Quote Link to comment Share on other sites More sharing options...
psw Posted August 2, 2008 Report Share Posted August 2, 2008 That's right, ferrous metals do have an effect and as was said, in a cover could completely isolate the strings from all of the magnetic field. However, since this thread has moved from covers to pickup designs...use of ferrous metals (or even magnets) can be used to alter the focus and direction of magnetic fields to beneficial effect. For instance, I have been impressed with a lot of the new noiseless stacked pickups that have been developed in recent times. Kinman uses a metal shield around the lower coil to isolate it along with other strategies. Fender Noiseless pickups have a central magnet between the top and bottom coils (instead of a magnet below or normal magnetized coils). I recently installed an SCN (designed by lawrence) pickup and these too have a central magnet between two coils in a stack, but also has powerful rare earth magnets in the outer edge to pull the field in quite dramatically...the sides of the pickups have the strongest attraction. Personally I have found all of these designs to be very good in both sound and noise canceling qualities. So, it you were to have a pickup with an open top but a ferrous outer edge to a cover, this may have some qualities that might benefit a pickup design. An eBow for instance uses coils with such an arrangement to allow the driver and pickup to be far closer without oscillation and to keep the coils tightly focussed on a point of the string. pete Quote Link to comment Share on other sites More sharing options...
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