Alumitone whistling

[the great waldo]

Hi All

I had a customer in yesterday who has an 8 string guitar with alumitone pickups that whistle. Has anyone had similar problems and is it wise to wax the pickups. I've got a set in another guitar in for a setup and I must say the insides from what I can see look a bit fragile. Any opinions ?

Cheers

Andrew

[Stratz]

I have no experience with Alumitone pickups but I've dealt with Lace before and the customer service was very good. Lace may even be a member here.
I'd contact Lace customer service and describe the issue. Tell them youre a pickup builder and see what they say about wax potting.

Phone: (714) 898-2776
Email: Info@LaceMusic.com

Business Hours
Monday - Friday 9am to 5pm PST
Saturday - Closed
Sunday - Closed

[madzub]

the primary, that is the aluminium frame, picks up physical vibration easily, like when you tap on it with a pick it's very loud. so probably under high gain the frame is vibrating against the body or a screw, or it could be the secondary is vibrating against the primary. tighten it down, use rubber tubing around the screws, waxing could help to secure all parts.

[Dave R. -Turnbull-]

Hey there, first post. The alumitones use Barium Titonate. They are built with a ceramic magnet with copper tape as the upper conductive surface -lead soldered- from there a layer of Barium Titonate and capped with another layer of copper tape -lead soldered- with a piece of fridge magnet material. These if I recall are sent to a 1.8 milihenry <--(?) inductor choke. The only coils that would need waxing exist in the choke. Waxing the frame would most likely cause damage to the Barium Titonate. If they are whistling the conductive surfaces have most likely separated somewhere and general vibrations must be causing them to whistle. Do they continue to whistle when adding pressure to the underside of the magnets?

[Mike Sulzer]

What is the Barium Titonate for?

Hey there, first post. The alumitones use Barium Titonate. They are built with a ceramic magnet with copper tape as the upper conductive surface -lead soldered- from there a layer of Barium Titonate and capped with another layer of copper tape -lead soldered- with a piece of fridge magnet material. These if I recall are sent to a 1.8 milihenry <--(?) inductor choke. The only coils that would need waxing exist in the choke. Waxing the frame would most likely cause damage to the Barium Titonate. If they are whistling the conductive surfaces have most likely separated somewhere and general vibrations must be causing them to whistle. Do they continue to whistle when adding pressure to the underside of the magnets?

[Dave R. -Turnbull-]

What is the Barium Titonate for?

https://www.youtube.com/watch?v=rpmtztt5W08

The original Lace Sensors also use Barium Titonate. When looking at the diagram of the sensors you can see they have numerous pieces of what appears to be fridge magnet strips. Between these strips is Barium Titonate. Attached is a pic taken at NAMM -Lace booth- of the world famous Lace Sensor pickup as a display model.



Barium Titonate is really incredible stuff!!! You can make an acoustic bridge into a pickup if you want.... Make a guitar neck a giant pickup.... so long as you are able to maintain constant pressure... All these suggestions are purely hypothetical of course, but plausible.

[David Schwab]

Barium Titonate would be a piezo electric material. Lace Sensors do not have this. I've taken them apart. They do use rubberized ceramic magnets. Then they have the steel combs which are the pole pieces. That's about it.

Regarding the Alumitones, the frame is the primary winding. They tend to be microphonic. The small copper coils are a current transformer to step up the output. We have had many threads on these pickups.

Obviously you can't wax pot the frame. But if you could paint some epoxy on the underside it might firm things up enough to stop the squealing.

[the great waldo]

Barium Titonate would be a piezo electric material. Lace Sensors do not have this. I've taken them apart. They do use rubberized ceramic magnets. Then they have the steel combs which are the pole pieces. That's about it.

Regarding the Alumitones, the frame is the primary winding. They tend to be microphonic. The small copper coils are a current transformer to step up the output. We have had many threads on these pickups.

Obviously you can't wax pot the frame. But if you could paint some epoxy on the underside it might firm things up enough to stop the squealing.

Hi David

Thanks for the info. The customer hasn't got back to me with the guitar, but I do have another guitar with alumitone pups in at the moment so i'll check out if they whistle.

Cheers

Andrew

[Joe Gwinn]

Regarding the Alumitones, the frame is the primary winding. They tend to be microphonic. The small copper coils are a current transformer to step up the output. We have had many threads on these pickups.

Obviously you can't wax pot the frame. But if you could paint some epoxy on the underside it might firm things up enough to stop the squealing.

You can pot the frame in a two-part soft urethane rubber that would be goopy enough to have the same damping effect as wax.

Or, clamp the frame against a bit of sorbothane rubber: McMaster-Carr

[fieldwrangler]

I've been wondering if I should try encasing the single-turn units I've been working with around here in maybe some thickish (1/16"?) clear sleeve that could go on like shrink - anyone have any knowledge or experience of such a material?

One reason for the desire to surround the element is that someone complained about how it sounded when they hit it with their pick...

Bob Palmieri

[bbsailor]

I've been wondering if I should try encasing the single-turn units I've been working with around here in maybe some thickish (1/16"?) clear sleeve that could go on like shrink - anyone have any knowledge or experience of such a material?

One reason for the desire to surround the element is that someone complained about how it sounded when they hit it with their pick...

Bob Palmieri

Bob and all,

Lace designed the Alumitone pickups to fit into the footprints of legacy pickup footprints. High gain amps and loose parts can cause microphonics in any type of transducer, voltage-based through the more modern current-based types. The key is to dampen any microphonics, typically due to loose parts, such as the "C-shaped" laminated cores going through the aluminum frame and coil bobbins. The key is to get it to ring and try various damping techniques to quiet it. Since this is a new technology, trial and error and sharing knowledge is the most efficient solution.

Here is an observation about the potential for these type of pickups and the benefits to building guitars without the need to rout a hole for the pickups in line with the strings tension on the body. A typical current based pickup can use a current transformer that occupies about 1 cubic inch with the string loop being only as tall as the wire thickness and magnet. This 1 cubic inch space is not in line with the string path. This means that the neck can be better coupled to the body with only a 1 cubic inch hole to accommodate the current transformer and the string loop and magnet bonded together in a variety of ways to eliminate potential microphonics , such as using heat shrink tubing or some type of caulking.

A good current transformer to try is the Prem Magnetics SPCT-251 (2000 turn secondary) that has a user installed primary opening to fit up to AWG 6 square copper wire. This wire is about .1620" square and about 30 microohms per inch. Using a total of 8 inches of AWG 6 square wire for the string loop will produce a calculated output impedance of 2000 squared or 4,000,000 times 30 X 8 or 240 microohms for an output impedance of 960 ohms plus a few hundred ohms for leakage inductance. Making a good low resistance joint in the string loop is key to maximizing the output of this type of pickup. Adding some type of soft epoxy or caulking where the string loop wire goes through the current transformer would also be good to experiment with. Preventing the string loop wire from vibrating against the magnet should also be done. With this type of pickup, using an on-guitar volume pot of about 15K to 25K ohms would be appropriate. Grounding the string loop and grounding the transformer metal frame can also help reduce noise. This should produce a wider bandwidth, low noise pickup and allow for better mechanical neck and string coupling to the body because there are no traditional pickup holes needed. Only time will tell if the early adopters of this concept hear any difference. However, this is something to think about in the evolution of the guitar.

Joseph J. Rogowski

[fieldwrangler]

In fact, I also believe in eliminating the need to route big holes right next to the neck joint.

However, sometimes a big hole in the string path, such as we see when carving out swimming pools in Strat bodies, can actually help some axes.

Bob p