Compressed sounding pickups

[David Schwab]

I'm assuming that your ceramic magnet has the poles on the flat surfaces, which I think some people have gotten confused about.

One thing to try would be to stick a thin piece of steel to the bottom of the magnet. This is how the Burns Tri-Sonics are made. It's a coil wound on a ceramic magnet with a steel plate on the bottom. The steel plate will increase the inductance and should warm up the tone of the pickup. It will also increase the output. Some of my first tries at making a pickup were very similar with the coils wound right on a ceramic magnet.

Regarding what DiMarzio is saying about the PAF swell, don't forget that they are using alnico magnets for the PAFs. Ceramic magnets are stronger and give a brighter tone that wont have that soft alnico tone.

Another thing to try would be a thin neo magnet with the poles on the flat faces. Neos tend to have more low end than ceramics, which can sound thin, but have that brighter tone like a ceramic.

[CRU JONES]

LVS,
You using the square ceramic magnets then right? I think your pickup suffers from having a high magnetic field gradient. my feeling is the magnetic field may only be strong localized to your magnet. the magnetic field gradient is determined by the size of the working air gap of your magnetic circuit. In your case you really don't have a magnetic circuit other than your magnet, which is small. I think it would be worth a try to put a "booster plate" on the bottom of your coil. Now your magnetic circuit would have a larger working air gap and the flux will be spread through a larger section of your coil.

Let us know how your project is going, I think it is interesting! :-)
Ethan

[David King]

I've had exactly the same experience when trying to wind this type of pickup (in an attempt to approximate a Lane Poor pu). I think it's the nature of ceramic magnets (the Chinese ones at least), they tend to scoop out the midrange leaving highs and lows behind. To me the sound is "constipated" but a lot of guys (bass players) love that sound. I can take it on a bass but I'd really dislike it on a guitar I think. Try shortening some A2 rods by 1/2 and wrapping them with 5500 turns of 43. Wrap up the whole thing in copper tape to shield it, you'll like it I think but you may need to re-magnetize it every few years due to the short aspect ratio. Still well worth the effort, the lower field strength works well with being close to the strings.

[LVS]

I don't know how deep you are into winding pickups

Not very deep. I've (re)wound somewhere between 20-30 pickups and over a long period, which isn't much but got me past the stage of too much tension, weird shaped coils, warped bobbins etc. 43 I still break occasionally, 42 is no problem.

My goal in pickup making is not producing batches of consistent and good sounding stuff, so I'm not a "maker", but rather, I grab occasions like this one - adding a second pickup to a old Framus - to try to build something that sounds nice and preferably somewhat personal and if it doesn't, okay, that was school money.

Anyway, thanks for all the answers so far. At this forum I'm interested in the comments of experienced makers as well as in the more scientific discussions, which in their sometimes ex-cathedra style produce a nice contrast.

Back to the pickup : For the moment I'm gonna stay with a ceramic magnet at least for a while. A steel bottom plate like suggested is certainly an option to put into the pipeline.

[RedHouse]

I'm not sure what causes pickups to be compressed or not, but the Rickenbacker Hi Gain pickups are quite compressed, especially the modern ones. They are like 14k with 44 gauge formvar and a ceramic magnet on the bottom of the coil. I like the older hi-gains more myself...they were like 9k - 10k and don't compress quite so much, though of course they are brighter sounding.

So maybe the ceramic magnet contributes to the compression since your pickup and the Ric hi-gains do also?

Greg

+1

[soundmasterg]

I'm assuming that your ceramic magnet has the poles on the flat surfaces, which I think some people have gotten confused about.

One thing to try would be to stick a thin piece of steel to the bottom of the magnet. This is how the Burns Tri-Sonics are made. It's a coil wound on a ceramic magnet with a steel plate on the bottom. The steel plate will increase the inductance and should warm up the tone of the pickup. It will also increase the output. Some of my first tries at making a pickup were very similar with the coils wound right on a ceramic magnet.

Regarding what DiMarzio is saying about the PAF swell, don't forget that they are using alnico magnets for the PAFs. Ceramic magnets are stronger and give a brighter tone that wont have that soft alnico tone.

Another thing to try would be a thin neo magnet with the poles on the flat faces. Neos tend to have more low end than ceramics, which can sound thin, but have that brighter tone like a ceramic.

Maybe that is how the new ones are made, but the vintage Burns Tri Sonics were made differently. Adrian Turner from Adeson pickups explained it to me this way in an email several years back >>

"Regarding the coils - all early European pickups (Hofner / Framus / Hoyer etc..) were built this way. The coil is wound on a removeable chassis - and then completely wrapped in a special armature winding tape (takes ages to learn this - they are ridiculously delicate!). The whole thing is pulled tight - just like lacing up your boots. The magnets are vintage ceramic (similar to Alnico 2). They have been out of production since the early seventies - I have to have them custom made - and they cost a fortune!!! The coils are then placed arround the bar magnets (the holes in the chrome top covers are purely aesthetic). The whole thing is then glued solid to prevent the brass top covers from causing howling. This is exactly how they were made 40 years ago - and they sound great!!!
" .....

Greg

[David Schwab]

Maybe that is how the new ones are made, but the vintage Burns Tri Sonics were made differently. Adrian Turner from Adeson pickups explained it to me this way in an email several years back >>

"Regarding the coils - all early European pickups (Hofner / Framus / Hoyer etc..) were built this way. The coil is wound on a removeable chassis - and then completely wrapped in a special armature winding tape (takes ages to learn this - they are ridiculously delicate!). The whole thing is pulled tight - just like lacing up your boots. The magnets are vintage ceramic (similar to Alnico 2). They have been out of production since the early seventies - I have to have them custom made - and they cost a fortune!!! The coils are then placed arround the bar magnets (the holes in the chrome top covers are purely aesthetic). The whole thing is then glued solid to prevent the brass top covers from causing howling. This is exactly how they were made 40 years ago - and they sound great!!!
" .....

Greg

That's what I said, and it was from Adeson that I got the info. The coils are placed around the ceramic magnets. The bottom plate is steel. I didn't bother to explain that the coils had no bobbins, the point was that there are no steel pole pieces. Just the magnet and coil.

A lot of the cheap ceramic magnets you find on cheap Strat pickups are weak enough to be like alnico 2.

[LVS]

Here's a drawing of the current incarnation. I suppose this way is the lowest I can achieve, and the distance to the strings is now some 5mm (0.2"). Which is rather good I think.



The bottom plate is a rectangular L-shaped piece of hard aluminum. I can't measure thickness right now cause the pickup is mounted, but it's about 1mm (0.04").

The top plate is a piece of electronic circuit board with the copper layer on the outside.

I glued the magnet with 2-component epoxy, but this wouldn't stick solidly to the aluminum. I then drilled a lot of tiny holes through the aluminum and reamed them at the outside, to give the epoxy a better grip. That worked, but then the epoxy wouldn't stick to the ferrite very well, though I had cleaned the surface of the magnet thoroughly. So to make sure the structure would not come apart I eventually added two copper screws to hold everything together, and which also provide a ground connection for the copper layer on top : the pickup is screwed against the cavity and since the cavity is coated with a conductive shield, the top and bottom of the pickup become part of that shield too.

Compared to previous attempts the sound has improved. It's still bright but less piercing than the original pickup at the neck (thanks to eddy currents? Or is this magnet different?). Loading the pickups with a varying resistance, I played a bit with the resonance peak, to get an idea about pot values. I might try capacitor shunts too, but that's for later.

There is still a little bit of "compression", but not like before. Output level is a tad stronger than the neck pickup, and compared to the bridge pickup of my Höfner Strat, a little weaker. The distance to the bridge is about the same as with a Strat.

The bridge pickup is a little more sensitive to hum than the neck one, but that didn't come as a surprise since it has larger area x turns. Together in series they buck hum and still sound quite bright.

I tried a thin steel plate under the pickup also. It made a slight difference, but I didn't spend enough time with this to give a reliable description of what the difference actually is.

At high gain the bridge pickup tends to squeal. Possible causes I can think of are, it isn't potted, or the aluminum isn't stiff enough or maybe a too resonant material, who knows. The pickup sits tight and solid against the body surface though and I can't lift it with my fingers. Mounting it with additional double sided tape under it didn't change anything. But the squeal is not a real problem, since I'm not into high gain.

Anyway, I'm gonna skip potting it and directly go to the next thing : make the same structure with a steel bottom plate instead of an aluminum one. In my metal scrapbox I found an L-shaped piece of chrome plated steel of 0.5mm (0.02") thickness that appears to be stiff enough.

By the way, I was trawling Youtube two days ago looking for sound samples of Tri-Sonics and found someone playing a Strat with Adesons. It sure sounded good but he also mentioned having an active boost on board.

[Mike Sulzer]

With aluminum below and copper above you have a lot of eddy currents. That is, the resonant peak is damped, and there could be some loss of signal in the mid-range. The pickup should sound less bright than a similar pickup without so much highly conductive metal. Not sure if this could be interpreted as "compressed", but it certainly does affect the sound.

For example, the steel cores of a humbucker have a definite effect on the response, both audible and measurable. But steel is a lot less conductive than either copper or aluminum. It is also highly magnetic, that is, has a high permeability, which helps reduce the eddy currents by forcing them to flow in a thinner layer at the surface of the cylinder. There is also a significant difference between a brass base plate and a so-called nickel-silver one. And of course, taking off the cover makes a difference.

So all the metal could contribute toward a more dull sound.

[soundmasterg]

That's what I said, and it was from Adeson that I got the info. The coils are placed around the ceramic magnets. The bottom plate is steel. I didn't bother to explain that the coils had no bobbins, the point was that there are no steel pole pieces. Just the magnet and coil.

A lot of the cheap ceramic magnets you find on cheap Strat pickups are weak enough to be like alnico 2.

Thanks David....I guess I misunderstood what you were getting at there.

Greg

[bea]

Yes . Purpose was to make a match for the neck pickup (which is original - the guitar is a Framus Junior 6 from the seventies), having approximatily 4400 turns of 42awg around a ceramic bar magnet, thus internally resembling a lipstick.

According to Framus, the Junior 6 is a very very low cost guitar with one single coil PU. It roughly resembles a Fender jaguar with one single coil pickup which itself looks like a strat pickup clone. Or Do You mean the standard 6 which is an SG clone with two pickups?

Seriously: if You are not a collector but want to make musik with such an instrument, You would not give it vintage correct pickups resempling the crap from German standerd production Framus used in their low cost instruments (which, for those who do not know often have extremly good necks made from beech multiplex). Those guitars will probably become great with high quality PUs resembling the P90, PAF, Strat, Tele,... according to the musical needs.

And if You want to wire the pickups in order to keep the optical impression i would not adapt the concepts of low cost pickups but those of the famous archetypes of the respecting guitar.

[LeonWhite]

Just One more compression comment . . .

Has anyone else heard this effect (granted it's not compression in the true sense as noted above) on '60-'63 strats? As I'm in LA I can go to guitar center's big vintage store-in-store, and if you play a dozen of those strats in original condition, you'll hear this effect clearly. Not to mention you can play over 150,000 dollars 'list' of vintage guitars in one hour.

-L

[Corona Blue]

Pickups that are very weak (comparatively speaking) tend to sound compressed to me. Also, if they are very OVER wound they'll compress and/or induce clipping further down the line of amplification.

I've found dynamics/envelope to be most influenced by form factor, specifically how the magnetic field is managed with the magnets and ferromagnetic materials. Magnets as slugs sound more percussive to me than steel slugs with magnets underneath. Ceramics sound sharper, etc. People better versed in the pedigree of alnico can specify how the different types behave. Blades have a whole different character... you get the idea.

Oh, and I understood your use of the word "compressed" to mean that it has a limited and dry sounding dynamic range, not that it is actually compressed... as peskywinnets pointed out, compression doesn't happen in passive devices... well, not really. I guess you could call some of the loading in the coil to be a type of compression, but I'll let Mike or Joe or one of those guys address that before I make a fool of myself.

^^This^^


Each magnetic alloy reacts differently to the flux of the steel strings. Gauss level of the magnet comes into play as well. As an example: The field of A2 seems to collapse when given high amplitude flux within the field (especially with a steel string). And as amplitude falls off, the field begins to re-establish and the AC voltage comes up. Sonically, this resembles the workings of a voltage limiting amplifier. (attack, compression, release). We call it pickup "bloom."

Then there's wire guage, TPL, tension, phase of the moon, sunspots, mood of your girlfriend...

[Mike Sulzer]

^^This^^


Each magnetic alloy reacts differently to the flux of the steel strings. Gauss level of the magnet comes into play as well. As an example: The field of A2 seems to collapse when given high amplitude flux within the field (especially with a steel string). And as amplitude falls off, the field begins to re-establish and the AC voltage comes up. Sonically, this resembles the workings of a voltage limiting amplifier. (attack, compression, release). We call it pickup "bloom."

A vibrating guitar string does not cause the magnetic field to collapse.

[Corona Blue]

A vibrating guitar string does not cause the magnetic field to collapse.

Ok... but it seems something is happening to create the perceived compression effect in say an A2 loaded humbucker. I can substitute an A3, A5 or Ceramic bar in the same pickup and the effect is less pronounced. I would think most of us here have experienced this first hand.