a charlie christian replica: believing my ears or theory?

[frenchy]

Good morning everyone and cheers from the north of the france!

As i just start building two projects right now (a full rosewood stratocaster and a Les paul Junior with a CC in neck position - cf model of Lennon) i decide to stop burning money in pickups For the stratocaster pickups, it is not realy difficult to find magnets. But for the building of a charlie christian replica....i would say: no comment.
I already have the 38 gauges wire but, after having browsed every suppliers website, apart for the 400dollars commands, no one is able to get me magnets at the expected dimensions.
Someone that have big audience in France (JP Bourgeois) developed an interesting theory on what makes a charlie christian sound so special. For him, the main reason came from "the great length of strings that is immersed in the magnetic field" (Gibson "Charlie Christian"). If we agree, it means that without long magnets bars, i will never have the sound of this famous pickup.
On the other side, the sound of the lollar CC is so similar that i could not say, on a blind test, wich one is authentic (yes, i am deaf, no joking). I assume lollar use 38gauges, but no other information can be found on the winding, the (potential) pattern, etc.

My question is simple: do i must believe our JpBourgeois - no long magnets no cc sound?
Must i believe my poor ears and start building a cc on the dimensions of a P90 (good point: a dangerous routing operation can be avoid)?

Here a child's drawing - mine actually- that present something, a pickup i guess :-)
Do you think that could give something (i mean pleasant)

[FunkyKikuchiyo]

I'm not an expert on the CC pickups so I won't pretend to be, but one thing that jumped out at me is what Mr. Bourgeois said. I don't see how those long magnets could NOT affect the sound, but if the argument is that it creates an "aperture" for the string that is the whole length of the argument, I just don't think that is plausible. Those magnets were so long because it was needed to make it strong enough, so I can't imagine you're getting much magnetic pull through the top of the instrument - especially since those pickups were generally on archtops where the bridges keep the strings relatively far from the top as compared to a solid body, zero neck angle like a Fender. The meaningful magnetization of the string is most likely entirely determined by the blade itself, and the magnet's contribution is as a part of the electrical circuit and for its specific gauss/bh curve/etc, and not for its magnetic geometry.

But, that's just my gut feeling. I very well could be wrong.

[salvarsan]

The meaningful magnetization of the string is most likely entirely determined by the blade itself, and the magnet's contribution is as a part of the electrical circuit and for its specific gauss/bh curve/etc, and not for its magnetic geometry.

Sounds right to me, too.

You must put enough magnetic field on the strings so that the coil can sense the strings.
An Alnico 5 bar may be too strong, so partially demagnetizing it will give the timbre you want..

[jason lollar]

you can go on youtube and find a comparison of mine with a model using the large magnets and there is alot more similarities than differences. Those old magnets , those are so far away from the strings and from the business end of the attached pole piece I really doubt they sense much of anything down there about 1-3/4" away from the strings.

[Mike Sulzer]

you can go on youtube and find a comparison of mine with a model using the large magnets and there is alot more similarities than differences. Those old magnets , those are so far away from the strings and from the business end of the attached pole piece I really doubt they sense much of anything down there about 1-3/4" away from the strings.

That makes a lot of sense. In fact, you could say that magnets do not sense the changing magnetic field from the strings, the coil does. The magnet has one essential function: 1) magnetizing the strings, and two peripheral functions: 2) increasing the changing field from the strings by channeling it through the coil, because of its permeability, and 3) changing the inductance of the coil and its losses, and thus the properties of the circuit, due to its permeability and conductivity. Magnets inside of the coil are potentially more efective at 2 and 3 than magnets outside the coil, and magnets far away do less than those close. However, a really large chunk of high permeability material, even away from the coil might have some effect.

So you want to get the strength of the field right at the strings, and you want to find some way to get the circuit properties of the coil the same as the original. This can get complicated, but I do not think you need the original magnets if you are willing to do some experimenting.

[nekodensha]

Frenchy, as I understand it those massive cobalt-steel magnets on the original Charlie Christian pickups were used simply because no more powerful magnetic material was commercially available until the end of World War Two, when Alnico started to become widely commerically available.

I respect J-P Bourgeois' extensive knowledge, his website has helped me a lot. But as far as I can tell, the CC pickup's clarity seems to be determined by the coil's overall design and the narrowness of the aperture, more so than those enormous magnets.

Well, if using the original cobalt magnets, you will probably develop impressive routing skills just to fit them, and maybe some weightlifting expertise too, if playing standing up for any length of time. But you already have some essential ingredients for this recipe, the wire and the coil form. Surely alnico can also give you results just as good with far fewer difficulties involved in getting there.

[David Schwab]

I think a better way to do it, instead of using the alnico as the core of the coil and sticking the poles on top, would be to make a steel core in the shape of the original, and stick the alnico on the bottom like one half of a P-90. That would simulate the steel loading on the original as far as the poles, and the way the magnet was connected.

[Mike Sulzer]

I think a better way to do it, instead of using the alnico as the core of the coil and sticking the poles on top, would be to make a steel core in the shape of the original, and stick the alnico on the bottom like one half of a P-90. That would simulate the steel loading on the original as far as the poles, and the way the magnet was connected.

I do not think you have any reasonable expectation that it will sound like the original if you do not get the field strength at the strings and the coil inductance and Q the same as the original. If you can get hold of such measurements, then you can use a steel core like the original and enough steel or other magnetic material behind the coil to get the right inductance, etc. You can then add neo magnets to get the right field strength. (The neo magnets have low permeability and will act pretty just as a source of field strength.)

[jason lollar]

I always considered using a steel blade for the core like the originals was an essential part of the design.
The original magnets for the archtop version of that pickup were about off the top of my head 3.5 X 1 X .125 - there were two of them so they are not that heavy. The lap steels had 7 X 1.5 X .25 two pieces so those wre alot heavier

[StarryNight]

These guys seem to be making them: Charlie Christian Pickups - CC Pickups

[frenchy]

Good morning everyone and thanks for the time you give by answering to my question. I found the right forum, finally (few answers has been gave on the French forum lutherie amateur, some on MyLesPaul).
Jason, for the “deaf” thing, it wasn’t metaphorical;-) Thanks for your reactions and glad to see that American pickup creators are so engaged toward a community like the one gathered here on this forum. It is far from being trivial.
FunkyKikuchiyo, thanks for the clear and simple manner you have to give your answer: it really helps people like me who do not have scientific skills that fit to conception of pickup.
salvarsan, thanks for the demagnetization idea. Regarding what has been said here, I think I’ll rather use Alnico 2 magnet 
nekodansha, JpBourgois is a great expert that I could not criticize as I do not have the competences that would legitimate it. The Problem is that on French forums, I think, persons who do have those competences do not dare to express deviant ideas. I do not say that the Bourgois hypothese is wrong, but I am disappointed to see that ideas that you guys share here is in a state of scarcity in the words of French luthiers. So thanks for expressing a franc point of view.

StarryNight , here is a comparaison between the Jason Lollar CC and the one made by the guys from ccpickups. If we cannot believe the sound that came from youtube, we can trust the opinion (even if it is just an opinion) of the luthier Daniel Slaman that concludes the sounds of the two pickups are not that different. In other words, as you guys said, the magnets and their position cant explain what makes the Charlie Christian sounds so special. Rather, since it is the only common denominator - the pickups share those characteristics – the “blade” and 38awg
‪Daniel Slaman on Charlie Christian pickups; CC Pickups versus Lollar Pickups‬‏ - YouTube

Mike & David, I will use your design ideas!! Taking the magnet away from the string, using blade magnetized by an alnico 2 humbucker bar, without having to destroy 1/3 of the acajou of the LP: it sounds really great to me
What do you think of this: (I am not sure the use of MU-metal could be interesting here. I just wanted to constraint magnetism to the sole blade

[jason lollar]

the comparison in the video is indeed the UK made repro- thats why i posted it

[Possum]

These pickups have always fascinated me. One of our jam hosts has a '37 CC guitar and I just love that sound. Part of the sound is from the guitar itself, its basically a plywood type build, the back is totally FLAT. He told me he tried the pickup in a different guitar and it just sounded bad and put it back where it belongs.

I bought a dead one off Ebay from an EH100 I think it was, I forget the exact number, but its the cheaper version without the diamond shape top, rest of it is the same. The magnets aren't like anything you can buy, they weren't alnico. The CC pickups used several versions of blades and those blades are very unique metallurgically. The wire I found inside isn't what I've read from any source, that was a surprise. You really have to take into account all the small details like the cross bracing on the magnets etc. etc. all have an effect on eddy currents etc.

I've had two customers who bought the UK replicas, neither one liked them and begged me to "fix" them, but I declined, not knowing enough about them at the time. The bobbins on those fall apart. I'm working on doing a work-alike version but never seem to have the time to get to it ;-) Making a full replica would be a bitch to do, there's alot of parts and getting the magnets and blade right could be a major chore, plus no one makes the right wire. Finding blade stock wasn't easy and really you won't find a match for those blades as they were made. I may be able to restore mine to functioning, the wire seems to be in good shape but probably the start solder joint is dead, may try to unwind and rewind it with the same wire and pray like hell it survives ;-) I'm hopefully doing some listening tests this weekend and see if its worth pursuing any further. Getting an original is nearly impossible anymore, this one I got a discount on since it was dead. I also have a rare lap steel version I've never seen anywhere before with a rounded top with creme binding and a split blade, very strange design...

[frenchy]

Hello,

thanks Possum for the info. I think I remember a story like the one you talk about here: users of ccpickups that asks for application of modifications on their new Charlie christian-like pickup..By the way, it's maybe you elsewhere on this forum :-)
But for the rest of what you are saying, it is realy pessimistic relating what I was looking for when i strated the thread: making a pickup that could give a sound close to the one of the charlie christian. Not like the Lollar one, because it suppose a level of competences that is far far far away from me, not like the ccpickups one because it is now obvious that searching for magnets with original dimensions is not the best thing to do.
I do know that the sound of a CC is a complex alchemy, but the recipe you evoke here cannot be follow by amateur like me: type of metal, composition of wire (i thought it was just plain enameled 38awg), etc.
So, as a part time pickup builder that wants to build just one CC pickup, what suggestions?
Thanks again !!

[FunkyKikuchiyo]

(i thought it was just plain enameled 38awg)

Easier said than done. I've never been able to find anything except 42 and 43 in plain enamel - it seems guitar pickup winders are the only ones who ever want this stuff, so that is all that is made. Some companies can do between 40-44 for you, but it'll mean a massive minimum order that would be beyond practicality for anyone here, except maybe Jason or Frank. Maybe there is some way to get a hold of the stuff, but I've never found a way. That 36-41 range is really hard to find anything. I spent a fair amount of time looking but I did give up a bit early (changed my mind about how much it really meant to me after listening to samples of other people's work) so you may find some stuff I couldn't ever come up with.

I'm not even positive it is 38 PE, given Possum's assessment; I'm not sure what he meant by that. He has often noted that PE insulation thicknesses can be all over the map, so I guess that's what he's referring to...? How are you Dave, by the way? I've been meaning to email!

If I was chasing the CC sound (more than I am now, anyway) I'd give up on a replica and do my best to get the vibe of one. So, switch to SPN and a more common magnet - Mike's idea on the neos is a good one and is pretty darn close to what I do with my own pickups.