Rewards (??!!?) of Minimizing Eddy Current Losses

[fieldwrangler]

Folks -

So, I made 2 versions of these sidewinders I've been working on, quite similar except that one used a laminated core and one a solid core. Measured inductances and ac resistances (with the Extech) were quite similar at 120hz, divergent (as expected) at 1k.

The irony is that the laminated core device is SO sensitive to cable capacitance! The solid core displays a much more gentle effect in these tests.

It doesn't seem to be just that "there's more up there to hear." I suppose these eddy current effects appear as resistance in series with the reactive elements, and this laminated thing just has a higher Q. (Is this true?)

Anyway, it's so extreme that I'm actually hesitant about sending these laminated things out into the world, and I'm not fond of onboard buffers...

Bob Palmieri

[Jessica1988]

I can't help you and I expect you to get a satisfactory answer.Good luck..

[CRU JONES]

Folks -

So, I made 2 versions of these sidewinders I've been working on, quite similar except that one used a laminated core and one a solid core. Measured inductances and ac resistances (with the Extech) were quite similar at 120hz, divergent (as expected) at 1k.

The irony is that the laminated core device is SO sensitive to cable capacitance! The solid core displays a much more gentle effect in these tests.

It doesn't seem to be just that "there's more up there to hear." I suppose these eddy current effects appear as resistance in series with the reactive elements, and this laminated thing just has a higher Q. (Is this true?)

Anyway, it's so extreme that I'm actually hesitant about sending these laminated things out into the world, and I'm not fond of onboard buffers...

Bob Palmieri

Bob,

Eddy currents will linearize phase and dampen transient response. That is very interesting to hear. I would expect the cable capacitance to be because of the dampIng effects. I would love to hear sound samples, as you posted before! Keep up the good work!
Ethan

[fieldwrangler]

Bob,

Eddy currents will linearize phase and dampen transient response. That is very interesting to hear. I would expect the cable capacitance to be because of the dampIng effects. I would love to hear sound samples, as you posted before! Keep up the good work!
Ethan

Well... the transients are indeed smoother sounding on the solid core (which I put in the bridge position.)

Linearize the phase... didn't know from that.

I have a bunch of gigs at the moment but next week I'll put together an insert box to allow comparison of different capacitance values (or maybe just collect some patch cords & measure their lengths & capacitances) plug straight into the tweed Deluxe and post some clips by the end of the week.

Bob Palmieri

[FunkyKikuchiyo]

Interesting idea. I remember back when Lace Sensors were around, I always found cable quality to make a much larger difference with those than with other pickups, and I never quite worked out why. With some pickups the difference would be small, but with the lace sensors (among other pickups, namely modern uncovered humbuckers) the difference would be considerable. I always assumed it was an aural illusion, but perhaps there is more to it. Hmmm....

[David Schwab]

That's interesting. I guess the more highs you have, the more you hear it when the resonant peak is altered?

I tried out some magnetic stainless steel laminated blades for a pickup and found them to be too harsh sounding in the mids for that design. I liked the tone better when I switched to a solid 1018 blade. Of course I changed two things, so it's hard to tell which changed the tone more. They might have also worked better with a different winding.

I'm going to experiment with the laminated blades again, since I still have some of it left.

[CRU JONES]

Well... the transients are indeed smoother sounding on the solid core (which I put in the bridge position.)

Linearize the phase... didn't know from that.

I have a bunch of gigs at the moment but next week I'll put together an insert box to allow comparison of different capacitance values (or maybe just collect some patch cords & measure their lengths & capacitances) plug straight into the tweed Deluxe and post some clips by the end of the week.

Bob Palmieri

Bob,

Hold on a minute! The phase linearization that I stated above appears to depend on damping factor at resonance. I am browsing through my measurements of neck pickups trying to find the nicest sounding/worst phase response neck pickup and am noticing that the phase gets worse on highly damped pickups as eddy currents are increased. I think it is safe to say, that in your "laminated" pickup, the pickup is under-damped. I am guessing that at some damping factor the transition occurs where eddy's go from "helping Phase response" to "hurting phase response". Bringing up phase response may not even be the issue... but it is curious

Don't worry about the sound samples! I'm swamped too! I would really like to post some sound samples of some neck pickups in the thread about "clarity". I think Joe Gwinn might be onto something as all my pickups have gnarly phase response at 3kHz.

Ethan

[CRU JONES]

That's interesting. I guess the more highs you have, the more you hear it when the resonant peak is altered?

I tried out some magnetic stainless steel laminated blades for a pickup and found them to be too harsh sounding in the mids for that design. I liked the tone better when I switched to a solid 1018 blade. Of course I changed two things, so it's hard to tell which changed the tone more. They might have also worked better with a different winding.

I'm going to experiment with the laminated blades again, since I still have some of it left.

Or maybe three things. permeability of 1018 will be much lower than a transformer lamination, electrical conductivity will be much higher than a transformer lamination, and thickness must also play a part in eddy losses. Someone else may be able to elude what thickness could have to do with it. If you look at something like a power transformer, the laminations are stacked to go with the direction of the magnetic field and perpendicular to the magnetic field. in a "blade" humbucker, the laminations are perpendicular to the magnetic field and in the direction of the eddy currents. Not that that is bad, just an observation

[David Schwab]

Or maybe three things. permeability of 1018 will be much lower than a transformer lamination, electrical conductivity will be much higher than a transformer lamination, and thickness must also play a part in eddy losses. Someone else may be able to elude what thickness could have to do with it. If you look at something like a power transformer, the laminations are stacked to go with the direction of the magnetic field and perpendicular to the magnetic field. in a "blade" humbucker, the laminations are perpendicular to the magnetic field and in the direction of the eddy currents. Not that that is bad, just an observation

I wasn't using a transformer lamination. I would have liked to try that, but haven't found a source for that material. I was actually using type 430 stainless steel that I laminated myself. I was using two .025" thick pieces to form a 1/16" blade. No doubt the steel itself sounded very different from the 1018.

[CRU JONES]

I wasn't using a transformer lamination. I would have liked to try that, but haven't found a source for that material. I was actually using type 430 stainless steel that I laminated myself. I was using two .025" thick pieces to form a 1/16" blade. No doubt the steel itself sounded very different from the 1018.

David! Sorry! I'll read more carefully I have an incomplete data sheet that has the relative permeabilities. Relative permeability of 1018 = 529 and 430 stainless as 409... So, the opposite of what I was thinking.

The "I" from an "EI" transformer would probably work good for a blade I have a pile that are a good size, but have yet to do anything with them yet.

Ethan

[dai h.]

post #2 is some sort of (creepy) spambot:

Base caliber injectors? - Page 2 - Dodge Caliber SRT-4 Forums

[Joe Gwinn]

post #2 is some sort of (creepy) spambot:

Base caliber injectors? - Page 2 - Dodge Caliber SRT-4 Forums

The eyes appear to have been enlarged using Photoshop. To the point of looking slightly unreal.

[David Schwab]

post #2 is some sort of (creepy) spambot:

Base caliber injectors? - Page 2 - Dodge Caliber SRT-4 Forums

You know, I was thinking the same thing, but I did go and check to see if she made any posts, other than those kind of comments. And there was this one:

http://music-electronics-forum.com/t27607/#post239938

So I don't think it's a spam bot.

Maybe she just replies in similar ways? Seems kind of out of place at the Dodge forum.

So that is odd.

[David Schwab]

The eyes appear to have been enlarged using Photoshop. To the point of looking slightly unreal.

You will notice that her pupils line up with the corners of her mouth, so I don't think they were enlarged. Makeup will do wonders for the size of the eyes.



(I come from a family of artists so you learn this stuff at some point)

[dai h.]

You know, I was thinking the same thing, but I did go and check to see if she made any posts, other than those kind of comments. And there was this one:

http://music-electronics-forum.com/t27607/#post239938

So I don't think it's a spam bot.

Maybe she just replies in similar ways? Seems kind of out of place at the Dodge forum.

So that is odd.

I saw that and that was puzzling (since that post does appear to come from a human). Maybe the first one (with addition of the female face pic) is "real" to "get past the defences"? And also, I don't understand where the payoff is (there is usually a spam link somewhere in the sig or profile)--unless early post links have been disabled or something. The bot replies seem to be typically written with a vagueness where well-meaning responders reply or seem to end up thinking of the oddliness as "innocent newbie confusion" and don't notice the spam links (which survive in the posts and/or sig/profile, etc.).