Cryogenic treatment of guitars warning

[Rick Turner]

Terry,

I'd suggest a Strat pickup and a humbucker without cover. Maybe even have one of the other folks here do the tests for more rigor to the method.

Basically, the pickups should be tested untreated at a known temperature, then treated, then tested again at the same temperature. Then we should actually know something.

OH, might not be a bad idea to listen before and after, too, in the same guitar with fresh strings and exact same strings to pickup distance for a reasonably fair subjective test.

Down the road there could be other tests including double blind playing and listening sessions, but for now, I think pure measurements may tell us something.

I do think that bit about the permeability of austenitic vs. martensitic steel deserves more attention, particularly as it is well accepted that cryo treatment aids in the transition from "A" to "M".

Did I hear someone questioning whether changes in the material could possibly affect magnetic properties? Well, the answer is clearly "yes".

[big_teee]

I volunteer to make a Strat Single coil.
I can send it to Salvarsan to test, if he wants to test it.
Maybe someone else could provide the Humbucker.
Let me know.
I have some of those plastic bobbin strat pickups I can rewind, and you can slip the magnets in and out for testing.
Or I can make the standard Fender Forbon type?
T

[Rick Turner]

Now we're getting somewhere. Thanks.

BTW, it might also do something to Tele bridge pickup bottom plates...

[Rick Turner]

Let's keep it as utterly normal as possible...Forbon for the Strat...and wind it to '58 specs. Let's see if this whole thing does anything at all to classic designs where we all have a pretty good idea of what it is "supposed" to sound like. That's for the more subjective side of the testing, and it doesn't impact objective testing one way or another.

It would be nice if Frank Falbo, who was deeply involved in the SD Zephyr project, would chime in. Of anyone who posts here, he's got more experience with cryo treating pickups than anyone else. Of course there were so many differences with the Zephyrs (which, by the way, I think sound just great) that we can hardly pull out the cryo part of that pickup formula/equation. But Frank may just have experience with before and after cryo on those pickups, and that could be valid.

I guess the next frontier would be 99.999 pure copper and linear crystal copper...

Think I'll duck and cover now...

[salvarsan]

...Instead I'm met with fanaticism. People with more faith than brains. So the bottom line from my perspective is either prove me wrong, default to my position or choose to fly in the face of science and just "believe".

It shouldn't need to be said that the magnetic properties of pickup parts influence the sound the most. Not sure what you thought you wrote, but it looked a lot like saying "no it isn't; no it's not" without offering any proof or directions to supporting information, contrarianism, in a word.

I do the research for a workable hypothesis, model it when I can, and try to point in a useful direction. That's why I give search terms instead of scientific DOI links. Different eyes find different gems. They are there if you want to find them.

And one more thing. salvarsan, I have something you don't. I'm willing to be wrong for the sake of learning the truth. Even embarrassed. Maybe just tell me why you know what you do about it, as I have done. If your information is more recent I would be delighted read updated news on the subject if you can provide it.

I have inquisitiveness, interest in the details, and scientific literacy. Before you ask where the picture came from, consider that I may be the only one in the world stupid enough to do ab initio molecular orbital models of the drug Salvarsan (Frickin waste of computation but there it is).

Callaham Guitars and Frank Falbo (lead engineer on Seymour Duncan's Zephyr) have, as a result of their own experiences in pickup production, said that cryo treating pickup parts makes audible changes in sound, not huge ones but incremental and desirable ones. Why would they lie about something so minor?

Curiosity compelled me to find a working hypothesis about the effects of cryo treatments on guitar pickups. Well, I've put one out here and suggested a cheap way to test it objectively (i.e., test eqpt. not ears). It's obviously incomplete so anyone with an idea can jump in.

You might join the party by finding out thermal expansion coefficients for iron-cobalt (FeCo) alloys and nickel-aluminum (NiAl) alloys since they are what may plausibly fracture and reform in AlNiCo when cryo treated. If the coefficients are too different, cryo treatment may embrittle alnico and would be easily testable ... with a hammer. God, I love scientific empiricism when it needs only crude tools.

...or you might come up with a simple disproof.

To the search terms previously mentioned, add "cementite magnetic properties" and "steel permeability tables". scholar.google.com is a better engine if scientific docs don't glaze your eyes; even so, the abstracts are often good enough. This is significant because the carbon in iron is partly bound as cementite instead of entirely precipitated or solvated elemental carbon. To read the lit, a small amount of it (cementite) hardens the magnetic properties of iron well out of proportion to its weight fraction. How do you test it? Wrap a coil around it and measure inductance. LCR meters are getting cheaper.

[The Dude]

I'm not trying to stir up this shit storm any more than it already is, but I thought I should point out that we've migrated from deep freezing an entire guitar as the OP described initially to now only cryo treating the pickups- an entirely different argument, IMO.

An interesting experiment nonetheless, and I'll eagerly await the results.

[salvarsan]

So what does this experiment cost, and how much time, and does the ride home effect the parts?

It's not rocket surgery. Shipping might inflate the round trip to $20 with the turnaround ~ 1 week.

HB Slugs and strat magnet poles are cheap and abundant.

The test jig is nothing more than 1.5 inches of plastic soda straw with a couple hundred winds around it. I made one to separate out some A5 and A8 rods mixed together. Works like a charm.

The meter is the Extech LCR tester that a lot of folks here have. That one works even better than a charm.

Test the inductance of each piece before and after treatment.

I recommend treating and testing parts because the inductance changes are easier to see in isolation than in a finished pickup. Cheaper, too.

[Rick Turner]

But, Salvarsan, Chuck did offer "proof"! As a knife maker (not a pickup maker). And ten year old, selectively-chosen, un-cited "information". And then he hid behind the excuse of a paywall re. any up-to-date information.

Right there...that steel permeability bit...austenite vs. martensite...that's at least one place to start looking. A physical change to steel that makes a magnetic difference. And Gibson-style humbuckers have steel in very critical places...all the polepieces and steel coupling bar.

We have no idea what this might mean for AlNiCo, but more research turns up positive results with solid carbide milling cutters and router bits.

There's stuff we don't understand...yet.

Now let's get down to business.

And if the world is flat, then so be it. I like the Mercator projection just fine...but past this point, there be dragons...

[Rick Turner]

Dude, this is a pickup maker's forum, so it's only natural that we'd narrow our focus. If the moderators want to separate this out as a different thread, that would be fine, but here we are, and it's just now getting interesting.

BTW, I'm happy to pay for treating full pickups, pickup parts, or whatever for this experiment. Salvarsan, I understand your "separate out the bits", and I do not disagree, but why not do it all and also do the bits. I'd like to see what happens to a copper wire coil, too...or is that against the rules here? The golden eared hi-end hi-fi crowd seems to think there's something going on there, and they don't deal with anywhere near the length of wire that we do in a pickup coil. Develop a current in half a mile of magnet wire and see what happens. Hell, they claim results in phono pickup cartridge coils that have less wire in them than I cut off and throw away in an hour of winding.

[salvarsan]

I think doing entire pickups might be better as there would be something familiar to which to listen AND test "scientifically". I think we're interested in any potential change in the copper wire as well.

BTW, no change in copper alloys? :

Increase in MRR for EDM through cryogenic treatment

.

Excellent catch!!

For a direct link to the PDF, search on the article title "Study of the Effect of Cryogenic Treatment ofTool Electrodes during Electro Discharge Machining".

They said that resistivity decreased 5-6% and thermal conductivity increased for beryllium-copper wire.

[salvarsan]

Here's an interesting one re. permeability of austenitic vs. martesitic stainless steel:

Carpenter Technical Articles - Magnetic Properties of Stainless Steels

The type 400 magnetic steels are interesting but you need to remember that their average permeability is roughly 1/5 that of soft steel (1010 or 1018).

There's a reason why the Zephyr pickup poles have 430 stainless with a pure nickel core -- delivering enough field to the guitar strings. Neither the stainless nor the nickel will magnetize permanently, as do soft steels.

I'm tired now so someone else will need to figure out how a low BH hysteresis affects the pickup signal.

[Rick Turner]

Mike, re. your earlier comment about matching turns not DCR, with my trusty CoWeCo winder, I can nail the turns exactly and I can match coil DCR to +/- 1% @ 8500 turns of #44 wire. So I do. The key is in careful tensioning and buying wire from a good source. It kind of blows my mind that they can actually draw miles and miles of the stuff without breaking it and that it can be so consistent with over a mile of wire in one of my humbuckers.

[salvarsan]

BTW, I'm happy to pay for treating full pickups, pickup parts, or whatever for this experiment. Salvarsan, I understand your "separate out the bits", and I do not disagree, but why not do it all and also do the bits.

If it turns out that the improvements are irritatingly minor, then no salable pickups have been lost.

I'd like to see what happens to a copper wire coil, too...or is that against the rules here? The golden eared hi-end hi-fi crowd seems to think there's something going on there, and they don't deal with anywhere near the length of wire that we do in a pickup coil. Develop a current in half a mile of magnet wire and see what happens.

The cork-sniffing poseurs should limit their cork-sniffage to wines. 4% lower resistance over a couple thou feet of wire should be audible.

The thing to be cautious about is that though the magnets, steel poles, and wire may change individually by only 2-4%, the combined changes are what may be audible.

The pickup DCR reading needs to be accompanied by a temperature reading so the before/after resistances can be normalized to 68F.

[Rick Turner]

Fully understood, fully agreed.

What I've learned in lutherie (hands on with the process of building close to 5,000 instruments now...) is that we're all fighting for that last 2-4%. That's where the magic is. That's the Stradavari zone, to put it into violin terms.

And worst case, we wind up with an open coil situation and we lose a few...a very few coils. Big f-ing deal. I've cut away more than my share of dead coils and rewound. Love to make wigs out of scrap magnet wire...

[Rick Turner]

BTW, some of the best of the worst of the high-end high-fi weirdness is the love of expensive power cords. Which then plug into wall sockets and go to many feet of Romex before hitting the circuit breakers.

Balanced and filtered AC power conditioners I can understand. $300.00 power cords I cannot. Then there's the wacko with the magic lacquer and the guy with magic wooden knobs...

On the other hand, inverted cone gear mounting might just work.

Choose your battles well.