suhr and dummy coil...

[swt]

So what's the final conclusion?. Anybody tried to wind something that likes, works, or anything?. What about wire gauge, etc? Thanks a lot for any reply!

[BruceB]

I missed the previous discussion, and I have not tried to build one yet. However, I think it makes sense and could be useful for several applications.

For example, I would like to try something like this on my outboard reverb tank, since it picks up hum and radio signals when my band has performed in radio stations or near a powerful station.

I understand the design as an AM antenna coil (out of phase with the pickup coils) terminating to a resistance and/or capacitance pad. The pickup grounds are terminated to the same pad. Probably, the resistance is very small, like 10-20 ohms. The Suhr has adjustable pots to fine-tune the 'noise-canceling'. I would think these could be in series with the pickup and/or antenna grounds. Again, probably a low resistance.

The information I have read indicates you would NOT use RWRP setups with this approach. So, I would have to make some changes on my stock Fender pickup configurations.

The antenna coil may be difficult to make neatly and unobstrusive. It seems like I could experiment though with an old AM antenna from a transistor radio with a single pickup.

BruceB

[David Schwab]

For example, I would like to try something like this on my outboard reverb tank, since it picks up hum and radio signals when my band has performed in radio stations or near a powerful station.

Craig Anderton has a reverb tank setup that uses two sets of springs and is set up for hum cancelation.

Here's info, and the schematic too:

Hot Springs Reverb



.

[David Schwab]

Here's something interesting... I was reading the archives at www.mimf.com, and found this post about dummy coils by Rick Tuner from November, 2000:

Dummy coil area counts, too. You can enlarge the area picked up by the dummy coil and reduce the number of turns..... A series dummy coil made the same size as the perimeter of a control cavity and wound with fairly large wire might cancel a fair bit of hum with minimum effect on tone.....Just a thought.

Hmmmm, sound familiar? Seems like Turner invented Suhr's dummy coil!

[Mark Hammer]

I tried out a Suhr guitar with dummy coil at a recent trade show and was reasonably impressed. Of course standing right beside the power transformer in the amp introduced very audible hum, but when you realize what the gain of the amp was, it was not surprising or unreasonable hum.

The area thing is important in a couple of ways. First, it does allow for a modest number of turns to acquire sufficient hum to be useful for cancellation purposes. But beyond that, it accomplishes the neat trick of not being that much closer to one pickup than to any other. If the Strat was a two-pickup instrument like the old Alembics, with a dummy coil in the middle, that would be one thing. But when you have 3 pickups, just where do you put the coil so that it is equidistant? Suhr's solution, using the backplate, was brilliant: make it surround all of them!

[madialex]

I tried out a Suhr guitar with dummy coil at a recent trade show and was reasonably impressed. Of course standing right beside the power transformer in the amp introduced very audible hum, but when you realize what the gain of the amp was, it was not surprising or unreasonable hum.

The area thing is important in a couple of ways. First, it does allow for a modest number of turns to acquire sufficient hum to be useful for cancellation purposes. But beyond that, it accomplishes the neat trick of not being that much closer to one pickup than to any other. If the Strat was a two-pickup instrument like the old Alembics, with a dummy coil in the middle, that would be one thing. But when you have 3 pickups, just where do you put the coil so that it is equidistant? Suhr's solution, using the backplate, was brilliant: make it surround all of them!

I too have seen the whole system. It is made on the strats back plate which is slightly wider around to make up for the 1/4 inch coil. The coil I think is fairly low in resistance as it is very flat and only 1/4 inch wide and the whole backplate is covered by some black sprayed on material, maybe sheilding paint?? It also comes with a small PC board that has 2 or 3 very tiny trim pots to adjust the frequencys of each pickup to the noise signal generated therefore making them vitually noiseless. The one for the telecasters are made right in the guitar on the Suhr guitars. Pretty darn neat idea, my hats of to Mr. Surh.

[Mark Hammer]

And while it has been said many times over (on the old Ampage), it bears repeating: Even knocking 12db of hum level off, without changing the tone of single-coils that one has grown sentimentally attached to, and plans one's pick attack around, is, if not perfect, nevertheless a good thing.

[Joe Gwinn]

Here's something interesting... I was reading the archives at www.mimf.com, and found this post about dummy coils by Rick Tuner from November, 2000:



Hmmmm, sound familiar? Seems like Turner invented Suhr's dummy coil!

This might be worth some research. If one can legally establish a prior date at which the innovation was "anticipated", no patent.

Chilliachki filed what became application number US 2005/0204905 A1 on 14 March 2005, so it seems possible to likely that he was anticipated.

[David Schwab]

Well the post by Turner is dated and all, and obviously precedes Chilliachki's filing by 5 years!

I know if I had read that post, and there wasn't this patent, I'd be trying out ideas myself.

Could be parallel discovery... but that seems unlikely.

[madialex]

either way

He is getting 325.00 each for the system. Wish I could have been the one to come up with it.

[EtLa]

...

[Joe Gwinn]

Well the post by Turner is dated and all, and obviously precedes Chilliachki's filing by 5 years!

I know if I had read that post, and there wasn't this patent, I'd be trying out ideas myself.

Could be parallel discovery... but that seems unlikely.

I looked around the MIMF website, but could not find the posting you quoted. Where should I look?

I don't know if the USPTO accepts web dates or not, but if it's that long ago, five years, enough other sites will back the date up, perhaps sufficiently.

Parallel happens a lot, but in the US only the first to invent gets to patent the invention. In the rest of the world, it's first to file. In the entire world, if something has been publically known for five years, it cannot be patented, even by the true original inventor.

[jaysg]

He is getting 325.00 each for the system. Wish I could have been the one to come up with it.

I'd pay $80, which I think is fair. At an MSRP of $325, I'll wait until Steve A. comes out with a perfected design....

[David Schwab]

I looked around the MIMF website, but could not find the posting you quoted. Where should I look?

I don't know if the USPTO accepts web dates or not, but if it's that long ago, five years, enough other sites will back the date up, perhaps sufficiently.

Parallel happens a lot, but in the US only the first to invent gets to patent the invention. In the rest of the world, it's first to file. In the entire world, if something has been publically known for five years, it cannot be patented, even by the true original inventor.

Here's the whole post...

I'm going to try and find it again and submit the URL...

Rick Turner - 09:51am Nov 2, 2000
Resawing and Tonewoods
Jeez, I hate to come off like the old fart I am, but we did the dummy coil thing 30 years ago at Alembic. The pickups were relatively low impedance---1500 to 3000 turns of # 40, and at first, we series wired a dummy coil (wound the same physical size but with a plexi core)in series with each pickup. Then Ron Wickersham designed a preamp which could use a single smaller dummy coil and subtract the hum from each string pickup. On the classic Alembic preamp there are four trim pots: gain controls for each pickup and hum cancelling controls for each pickup. The closer the dummy coil is to the pickup coil, the more complete the hum cancellation will be; of course if it's so close that it's picking up the same string section read by the pickup, you'll get phase cancellation of signal. Dummy coil area counts, too. You can enlarge the area picked up by the dummy coil and reduce the number of turns..... A series dummy coil made the same size as the perimeter of a control cavity and wound with fairly large wire might cancel a fair bit of hum with minimum effect on tone.....Just a thought.

[EDIT] Here's the URL

Reinventing phantom ("dummy") coils to decrease hum in single coil pickups

[swt]

well this is an interesting reading...is it possible to get rid of the trimmers and just go for the dummy coil, for a partial but usable hum reduction??. i will experiment and research a little more...i have some old radio books 'round here...