Greetings from the Lace Pickups team!

[lex@lacemusic]

That depends.

If it's advertising for a cage fight between Lex and Frank Falbo at Seymour Duncan, I wouldn't object.

Lex: welcome to the sandbox.

Remember Mark Hammer's advice on keeping AGI/Lace patent numbers handy.

I remember when the AGI released the TransSensor. I liked it, warts and all.
Still have a set of California Specials installed in another guitar, too, so you might say I like copper.

-The Immoderator

I dont think Frank works for SD anymore, i could be wrong, but i thought he was doing his own line of guitars?? Either way, i as well would not object to a cage fight. Haha

[lex@lacemusic]

Interesting. I think the essence of the difference is that the Joe Rogowski method adds series resistance, not shunt resistance, because the added winding is on a second set of cores that makes it a separate magnetic circuit.

Also, welcome to the forum Mr. Lace! I've seen a few DIY pickups inspired by the Alumitones, so the mojo is out there.

Thanks! Im excited to be here, and Mr. Lace is my boss... lol

[bbsailor]

Depending on the Alumitone, wire is either 46 or 47, and have either 4800, 6300, and 7400 turns on each bobbin. All depending on the model of course. And also, each pickup has a specific layout of magnets which helps shape the sound around the turns. I think in the near future, Jeff Lace and i are gonna do some experimenting with the Alumitones and trying to unleash all the capabilities these monsters are hiding. We currently are in the works of designing a Music Man based Alumitone, its gonna be beefy as shit! But the tone control will be like no other MM imitation, so we're excited to see how the players like them. Once some initial R&D starts, ill create a new thread and show updates and current progress. Should be lots of fun!

Lex,

The resistance of the twin loops in the alumium frame dictates, to a great extent, the overall tone of the pickup. Your strat type single coil uses the thinest string loops while the humbucker design has a lower string loop resistance because the alumium frame is wider. I calculate the resistance of the string loop in micro-ohms as it is too low to measure accurately. Note the where the "C-shaped" laminates are placed on the frame is where the two loops are effectivly in series. This preserves the humbucking characteristis of the primary string loop as well as the humbucking effect of using two smaller under-frame coils.

Here are some things to try with your current humbucking Alumitone frame design.

1. Try using two sets of "C-shaped" laminations under the frame for the reflected impedance voicing that I mentioned in previous posts.

2. Try putting a wider ser of "C-shaped" laminations on the wider portion, next to it's current location) with two sets of "C-shaped" cores on each side and on each of the two humbucking string loops.

3. Try wiring the coils in series/parallel combinations or add switching for voice changes.


Remember that the impedance of the output changes at a rate equal to the square of the turns ratio which is usually 1 to the number of turns on the secondary plus any leakage inductance which is higher in the Alumitone design or current transformer design than in a typical audio transformer. With 7400 turns the impedance is equal to the resistance of the alumium frame loop plus the Al (inductance value) of the "C-shaped" transformer lamination which can be about 2.5 micro henries per turn of the alumium frame through the lamination. The impedance of a 300 micohms frame is 16428 ohms plus adding the reactance of 2.5 uH at 1000 Hz of .0157 ohms (much higher than the frame resiatnce) or about 850K ohms divided in a quarter or about 212K ohms if the two coils are in parallel. The impedance should also be calculated for the lower range of guitar frequencies closer to 100 Hz for a more realistic expectation of the response especially when you may be changing the effective Al value with a reflected impedance change.

Yes, keep us posted about your Music Man Alumitone progress. There is a lot of room to do some very innovative tonal things with the Alumitone current transformer based design. I have some very innovative ways to wire two pickups out of phase to obtain a varitone-like tonal change with only a few parts.

Joseph Rogowski

[lex@lacemusic]

Lex,

The resistance of the twin loops in the alumium frame dictates, to a great extent, the overall tone of the pickup. Your strat type single coil uses the thinest string loops while the humbucker design has a lower string loop resistance because the alumium frame is wider. I calculate the resistance of the string loop in micro-ohms as it is too low to measure accurately. Note the where the "C-shaped" laminates are placed on the frame is where the two loops are effectivly in series. This preserves the humbucking characteristis of the primary string loop as well as the humbucking effect of using two smaller under-frame coils.

Here are some things to try with your current humbucking Alumitone frame design.

1. Try using two sets of "C-shaped" laminations under the frame for the reflected impedance voicing that I mentioned in previous posts.

2. Try putting a wider ser of "C-shaped" laminations on the wider portion, next to it's current location) with two sets of "C-shaped" cores on each side and on each of the two humbucking string loops.

3. Try wiring the coils in series/parallel combinations or add switching for voice changes.


Remember that the impedance of the output changes at a rate equal to the square of the turns ratio which is usually 1 to the number of turns on the secondary plus any leakage inductance which is higher in the Alumitone design or current transformer design than in a typical audio transformer. With 7400 turns the impedance is equal to the resistance of the alumium frame loop plus the Al (inductance value) of the "C-shaped" transformer lamination which can be about 2.5 micro henries per turn of the alumium frame through the lamination. The impedance of a 300 micohms frame is 16428 ohms plus adding the reactance of 2.5 uH at 1000 Hz of .0157 ohms (much higher than the frame resiatnce) or about 850K ohms divided in a quarter or about 212K ohms if the two coils are in parallel. The impedance should also be calculated for the lower range of guitar frequencies closer to 100 Hz for a more realistic expectation of the response espicially when you may be changing the effective Al value with a reflected impedance change.

Yes, keep us posted about your Music Man Alumitone progress. There is a lot of room to do some very innovative tonal things with the Alumitone current transformer based design. I have some very innovative ways to wire two pickups out of phase to obtain a varitone-like tonal change with only a few parts.

Joseph Rogowski

Im definitely going to be playing around with a dual secondary option as you've described. We have a couple prototypes around the shop, but they were built years and years ago, so i wanted to create some myself. I've only been working for Lace for a little over a year so im still learning as i go. And all your information is greatly helping with that! Im the production manager/ Alumitone Specialist/ and also do alot of forum work. So its a little difficult to find time to be messing around with all these different configurations, but i can assure you i plan on getting to it sooner rather than later. Jeff and I have discussed a few times about opening a Lace Custom shop, which im very excited about, but thatll all come in time. Mainly going to pertain to the players who want specific colors of Alumitones, and aesthetic things to the pickups, not so much directed at changing the tone. But I do wanna try and get some new production models made with a dual secondary setup.

As for the MM Alumitone, Im currently drawing it up on Illustrator/Rhino-File, so when the finished design is done, ill be sure to post it. Im excited to hear your response on the new design. Shouldn't take more than a few weeks to get all the dimensions down and accurate. Then once done, we'll be sending the file to get machined. THEN comes the fun stuff... creating a new secondary with just the right resistance to accurately mimic and improve on the MM tone.

[bbsailor]

Im definitely going to be playing around with a dual secondary option as you've described. We have a couple prototypes around the shop, but they were built years and years ago, so i wanted to create some myself. I've only been working for Lace for a little over a year so im still learning as i go. And all your information is greatly helping with that! Im the production manager/ Alumitone Specialist/ and also do alot of forum work. So its a little difficult to find time to be messing around with all these different configurations, but i can assure you i plan on getting to it sooner rather than later. Jeff and I have discussed a few times about opening a Lace Custom shop, which im very excited about, but thatll all come in time. Mainly going to pertain to the players who want specific colors of Alumitones, and aesthetic things to the pickups, not so much directed at changing the tone. But I do wanna try and get some new production models made with a dual secondary setup.

As for the MM Alumitone, Im currently drawing it up on Illustrator/Rhino-File, so when the finished design is done, ill be sure to post it. Im excited to hear your response on the new design. Shouldn't take more than a few weeks to get all the dimensions down and accurate. Then once done, we'll be sending the file to get machined. THEN comes the fun stuff... creating a new secondary with just the right resistance to accurately mimic and improve on the MM tone.

Lex,

Before you get too far in drawing up the final design, play with some options in placing a new arrangement of coils under the frame. The attached image shows the "C-shaped" laminations through the center of the side frame. Other options include placing two sets on the side frame rather than in the center or add another two sets on the side frame or one set on the center of one side and two sets on the other end of the frame for a variable tone alteration.

The advantage of using a pressed or cut alumium frame is that there is no joint that needs to be maintained. It's the interlocking "C-shaped" laminations that allows the frame to function like a single coil loop in a current transformer. However the length of the alumium frame in the Alumitone design puts less of the primary coil in the magnetic circuit than a U shaped loop going through an E-I frame like the Prem Magnetics SPCT-251 CT type. You may want to think about creative ways to put more of the Alumitone frame in the magnetic circuit by using a larger interlocking E-type core to improve the primary string loop coupling to the under coils. Obtain a few Prem Magnetics SPCT-251 CT and play with them and transfer these characteristics to the Alumitone and calculate the leakage inductance. When you use a pair of CTs on each end of the string loop there will be better coupling using E-I type cores with a longer U-shaped wire than the way the Alumitone does it with short center alumium frames section going through the "C-shaped" laminations. Optimizing the magnetic coupling is where the true opportunities exist for making a much more innovative and variable voicing addition to your design.

Let the fun begin!!!

Joseph Rogowski

[bbsailor]

Lex,

Here is another design tip that will help you squeeze the best frequency response from your unique Alumitone pickup shell. The shell uses alumium which is about .125" thick and the upper frequency harmonics of guitar strings go up to about the 7th harmonic. Since Alumitone pickups are current dependent the higher frequencies which contain subtle and delicate harmonics will be supressed by the eddy currents being generated the solid alumium shell primary string coils limiting the current of those higher, delicate frequencies and ultimately minimizing the magnetic transfer of these frequencies to the output coils underneath the frame. Higher frequencies tend to migrate to the outer portion of the coil wire thus Litz wire with individually insulated strands preserves the current at higher frequencies.

See this:http://thayer.dartmouth.edu/inductor/papers/litzj.pdf and this http://www.litzwire.com/nepdfs/Round_Litz_Catalog.pdf


Consider making a few prototype shells made up of about 10 to 12 .01" thick layers initially made flat and then bent into the typical Alumitone shell with the coils underneath. This will allow you to listen and measure for a difference in high frequency harmonics that should be more preserved and not be subject to eddy current attenuation of the thicker shells. A thickness of .01" should maintain a flat response up to 10Khz. Since the highest guitar frequency is 1312hz at the 24th fret of the high E string, you will preserve the typically lost range of guitar sounds well up and slightly beyond the 7th harmonic of the highest guitar fundamental note. You may even want to try making many thin layers or laminations out of copper, with lower resistance than aluminum, with a very thin paint insulation to insulate each layer to minimize eddy currents. These new pickups could then be called the "Lamitones" or "Litztones". Trademark hint!

Enjoy

Joseph Rogowski

[Possum]

I just speed read thru this, don't know if anyone mentioned it but the Alumatone is not a new idea at all. There was a guitar pickup back in the 30's? that used the same single turn with transformer idea. Maybe someone can dig the photo of that thing up, don't remember if it was patented, but I do remember seeing a photo of the original.....my memory is real vague on this but I know someone pointed this out before a couple years ago.....

some patents from old threads but not the ones I was looking for:

6897369 Alumatone patent

5,831,196 Khangov patent

[David Schwab]

hence... the birth of The Alumitone.

Or more precisely, the birth of the Transsensor, since that came first. I see Lace dropped those from its lineup.

[copperheadroads]

I dont think Frank works for SD anymore, i could be wrong, but i thought he was doing his own line of guitars?? Either way, i as well would not object to a cage fight. Haha

I thought Frank Left SD & is probably working on his own guitars & working on his "Intension Bridge Technology"
I hope he stays in the forums ,He's been a great asset to many forums .........
Also ... lex@lacemusic , Welcome to the forum

[bbsailor]

Thanks, Joseph, I think I see what you are doing now. You have described a system in which the second secondary is actually a separate inductor in series with the string loop. With the second secondary open you have an inductance in series with the string loop, and this inductance has a capacitance in parallel. This capacitance is the winding capacitance of the secondary multiplied by one million. Shorting the winding make the series impedance very small. From the point of view of the external circuit, I think this offers the same possibilities as putting circuit elements in series with the secondary of the unmodified system.

From your earlier description, it was not clear that the two secondaries have no mutual impedance as is the case for the system you have just described.

Mike,
The second coil, when open, causes the low impoedance string loop to have the inductance of the second coil lamination frame raise the impedance of the primary string loop. Then, when the second coil is shorted out or when a capacitor is placed across the second coil, the total impedance of the string loop changes and forms a tone equalization circuit that takes place in the low microohm low impedance string loop. You are correct in that the capacitance of the wire in the second coil also comes into play but the tonal change comes more from the reflected impedance change caused by the second coil and lamination set affecting the primary string loop impedance. Here is where thinking in terms of current and very low resistance plus all the factors that transformers, like leakage inductance, bring into this pickup design, and where tonal change opportunities exist that are not obvious at first glance. Think in terms of the calculated resistance of the string loop, plus the Al (inductance value) of that part of the string loop that goes through the secondary coil laminations. Some typical current transformers list the Al value as 2500nH or 2.5 uH per turn and this impedance is in series with the string loop primary.


Take two Triad CSE-187L CTs with "U-shaped" primary loops and join the primaries to form a continuous loop. Measure one CT with the Extech LCR at 1Khz and see that you read 890 ohms when the other CT is open. Then when the other second CT is shorted the other CT now reads 140 ohms. When a CSE-187L CT has its "U-shaped" primary leads bent to form a shorted loop, the secondary now reads 80 ohms.

The Prem Magnetics SPCT-251 is a 2000 turn CT that reads 8.5H at 1Khz and 35.99 K ohms with a Q of 1.489 with no primary turn added. With a square AWG 6 tight loop placed around the primay its impedance now reads 888.1 ohms at 1Khz, 145.51 mH with a Q of 1.030. The SPCT-251 uses a more efficient core with a higher AL value. Since off the shelf CTs are uses to higher read power levels, they design cores not to saturate. With guitar pickups the output current is in the low fractions of amps range and could use core types like those used in low level input transformers with impedance reflection changes being more extreme.

Additional thought. The measured Al value of the SPCT-251 at 1000Hz is 2.1uH per turn (8.5H divided by TR squared) but at 120 Hz it is about 5 uH per turn (20.5 divided by 4,000,000).
Typically, the frequency range of E-I type laminated frames is between 50Hz and about 400Hz while some toroid types are designed to operate in the 20Khz to several Mhz range. By choosing a core type and listening to various types provides a simple way to voice current-based type pickups. Bode plots also help visually document the effect. Surplus Sales of Nebraska has some Vitec 300/350 turn CTs available at a low price. These should work well with the Shure A95U series mic matching transformer with the primary option for 75 ohm (low range) center tap is done. The output impedance at 1Khz is about 43ohms with a primary string loop of about 250 uohms.

Joseph Rogowski

[lex@lacemusic]

I thought Frank Left SD & is probably working on his own guitars & working on his "Intension Bridge Technology"
I hope he stays in the forums ,He's been a great asset to many forums .........
Also ... lex@lacemusic , Welcome to the forum

Thanks! Excited to be here! Although, i dont get to spend as much time reading on here than id like. Building pickups and pickguards consumes my life these days!

But yea, i looked him up and it appears hes doing the bridge technology now, hope he chimes in on some future posts though! Would be cool to get a little info/insight from such an experienced pickup artist!

[David Schwab]

Falbo Guitars

Frank, if you are reading this; your guitars look very nice. But why are you still hammering in frets, and with a ball-peen hammer no less? Press them in man!

[rjb]

Acoustic Bridge Sidebar

Falbo Guitars

I watched the Intension Bridge vid and am not sure I clearly understand how the strings attach to the guitar!
Do you happen to know of a relevant patent?

[the great waldo]

Nothing wrong with using a hammer to seat frets. I've been using the same 8 oz stanley hammer for 30 years, broke the shaft 20 years ago and glued it back with titebond and it's still holding strong. It's horses for courses. It's nice to be able to but some tactile feeling into fretting a guitar. I suppose if I was making 10 guitars a day I would press them in, or maybe not, or I could always get a cnc machine to put them in. But then it kind of defeats the object of being a guitar maker and making something by hand the old fashioned way. Each guitar player plays differently and has a different feeling lets hope that stays that way. Just my thrupence worth.

Cheers

Andrew

Falbo Guitars

Frank, if you are reading this; your guitars look very nice. But why are you still hammering in frets, and with a ball-peen hammer no less? Press them in man!

[Steve A.]

Hey everyone! Just found this forum and am excited to get on here and start talking to fellow builders/designers about some rad pickups! Here at Lace we have a technology that no one can match, but that doesnt mean we dont like traditional pickups or helping out with information regarding our pickups and other pickups!

I bought a Lace Sensor Hot Gold set a few years ago and managed to lose the mounting hardware. Can you post what sort of screws I should look for: thread, length, type of head, type of metal? I have silicone tubing so I don't need that. I was going to take the set down to Ace Hdwr to figure out the thread but with you joining our forum I thought I would ask you instead.

BTW a lot of lap steel players over at the Steel Guitar Forum are starting to use your Alumitones. I see that there are 3 different X-Bars for 6 to 10 strings. You have the dimensions listed but I was wondering if the actual sensing area was less than that. An 8 string steel with 3/8" string spacing works out to 2.625" from the 1st to the 8th string. 10 strings usually have a narrower spacing so it would be around 3" from the 1st to the 10th string.

Thanks!

Steve Ahola