Basses with dummy coils …

[ardgedee]

How expensive is a dummy coil?

In a sense, it's just a pickup without the magnet. Running with that premise, you could reasonably assume it would be cheaper than a pickup since there's no added material cost for the magnet (and metal core, if the magnet is under the pickup). On the other hand it would probably be more expensive since it would require a separate assembly line process from the pickups that get churned out in the thousands.

If a dummy coil has to be tuned specifically to the pickup it's paired with, that's even more expense. Quality Assurance is expensive.

 

[bucephylus]

Post 64

Oh. I see - you stepped in after that. Anyway, my response to post 64 is where you got confused.

I'm NOT confused.

But, I may have confused you, by quoting your Post 70. My Q's were more based on your Posts 52 and 53, which seemed to be implying that the Alembic circuit had an inherent noise issue. I do not agree with that assertion; so, I was questioning your broader statements.

 

[Scarysharkface]

So wait. Are Alembic Series basses not truly single coil either? Does their dummy coil sap part of the audio signal?

Their dummy coil is added, out of phase, to the active circuit. It's a brilliant concept (in so many ways) that works. It picks up the same interference as the single coil pickups, which is added to the signal out of phase to cancel said noise.

John

 

[micguy]

I'm NOT confused.

But, I may have confused you, by quoting your Post 70. My Q's were more based on your Posts 52 and 53, which seemed to be implying that the Alembic circuit had an inherent noise issue. I do not agree with that assertion; so, I was questioning your broader statements.

Summing two preamps, one of which has signal, and the other of which doesn't, will give you more hiss than a single preamp. That difference is 3dB if we assume that both preamps are fed with the same impedances, the noise is uncorrelated, and have similar gains. Whether or not the resultant noise is an "issue" depends on a lot of things (including the user's noise tolerance), but the topology does have that disadvantage. The post of mine that you mention is pretty clear, it discusses this disadvantage, which anyone familiar with low noise audio circuit design will understand, but it does not use the word "issue".

If you take an Alembic with this circuit, put the bass in a situation where there isn't a hum field (so that the hum cancellation isn't needed), and then you carefully excise the hum cancellation preamp, the noise level (whatever it is) will go down - every stage in an audio device has inherent noise. Whether or not that's an issue for the user I don't know, I'm just sharing my expertise, and discussing the pros and cons of various schemes.

 

[FugaziBomb]

I wouldn't want to put a dummy coil in any of my basses. There's already a dummy playing them.

 

[atquinn]

I wouldn't want to put a dummy coil in any of my basses. There's already a dummy playing them.

I resemble that remark

 

[hooky_marr]

These 8-microcoil J pickups from Lawing are pretty cool. I have some of his Strat pickups and they are super clean.

 

[Snert]

The Zexcoils aren't the same thing.

 

[bucephylus]

Summing two preamps, one of which has signal, and the other of which doesn't, will give you more hiss than a single preamp. That difference is 3dB if we assume that both preamps are fed with the same impedances, the noise is uncorrelated, and have similar gains. Whether or not the resultant noise is an "issue" depends on a lot of things (including the user's noise tolerance), but the topology does have that disadvantage. The post of mine that you mention is pretty clear, it discusses this disadvantage, which anyone familiar with low noise audio circuit design will understand, but it does not use the word "issue".

If you take an Alembic with this circuit, put the bass in a situation where there isn't a hum field (so that the hum cancellation isn't needed), and then you carefully excise the hum cancellation preamp, the noise level (whatever it is) will go down - every stage in an audio device has inherent noise. Whether or not that's an issue for the user I don't know, I'm just sharing my expertise, and discussing the pros and cons of various schemes.

I understand you have certain preamp experience; but, you are essentially implying that the Alembic circuit topology inherently has noise issues.

Since that behavior is not borne out by actual performance experience, it would seem that Ron Wickersham found some practical means to address the point of your concern. Since neither of us has the actual circuit diagram in front of us, further analytical discussion has limited value. This is possibly one reason that the Alembic circuit remains uncopied; years after the patents have expired, and possibly due to undocumented trade IP.

 

[Jerry Catanescu]

I used a dummy coil in a preamp of my own design, on a Strat-style guitar. It worked, of course. It's hard to tune for all situations though. You have one dummy, and 2 if not 3 working pickups. The spectral makeup of the noise picked up by the normal pickups changes with the pickup selection. If you adjust the preamp to optimize noise cancellation with the bridge pickup, it won't be optimal anymore when you use two pickups together, or when you use the neck pickup if a different model from the bridge. Or even if the same model, but angled slightly differently, so it picks up noise differently from the dummy.

Long story short, while the dummy worked, it was a complicated, finicky system, with imperfect results, so like everyone else, I eventually abandoned it and went with "noiseless" pickups.

 

[micguy]

I understand you have certain preamp experience; but, you are essentially implying that the Alembic circuit topology inherently has noise issues.

I'm saying it trades off 3 dB more noise (of the hiss variety) in exchange for summing in the cancellation signal. If I were having this discussion with some of the other Audio Engineers I used to work with, they'd be nodding their heads without any discussion - signal summation is audio 101 stuff - at this point, we'd move on to the next topic.

That doesn't mean it inherently has "noise issues" - it means it has a bit more hiss than if it didn't have the cancellation signal path. Given that hum in single coils is usually well above the hiss level, it's probably a good tradeoff.

If the preamp in question has really good circuitry in both paths, chances are it could be quieter than a lot of onboard active preamps, many of which trade off a bunch of hiss in exchange for long battery life - many onboard bass preamps use low power op amps, which aren't very quiet.

My point is... no matter where it ends up noise wise, it could be a bit quieter (hiss wise) without the cancellation path. That's an inherent tradeoff with that design. That's it - nothing more implied.

 

[micguy]

I used a dummy coil in a preamp of my own design, on a Strat-style guitar. It worked, of course. It's hard to tune for all situations though. You have one dummy, and 2 if not 3 working pickups. The spectral makeup of the noise picked up by the normal pickups changes with the pickup selection.

Hum cancellation only works well if the two things have not only the same amount of noise - the amplitudes and the phase shifts of each half need to be the same over frequency - you have to match things well for it to really work.

On interesting sort of exception - with 3 identical pickups, two of which are the same polarity, and the 3rd the opposite, you can get hum cancelling with the two of the same polarity in series, with that combination in parallel with the remaining pickup - the series combination has twice the voltage unloaded, but also twice the impedance - when they are all put together, the loading of the various impedances gives you complete cancellation. I've tried this - the hum cancellation worked very well, but the sound of that connection scheme wasn't appealing.

 

[DaveParker39]

Since the classic dummy coil setup is also *not* tonally transparent and is far more cumbersome to install than a set of pickups that are designed to be hum cancelling, there's just no need.

There are the more complex setups, like the ones manufactured by Illitch are perhaps more transparent, but a rather large undertaking to install and dial in in comparison to just buying a set of nice hum cancelling pickups.I have this setup in a Les Paul with P-90's. It's pretty transparent, if I had to do it again I'd probably buy stacked P-90's instead.

I guess the short answer is we've evolved past the need for dummy coils.

 

[bucephylus]

I'm saying it trades off 3 dB more noise (of the hiss variety) in exchange for summing in the cancellation signal. If I were having this discussion with some of the other Audio Engineers I used to work with, they'd be nodding their heads without any discussion - signal summation is audio 101 stuff - at this point, we'd move on to the next topic.

As previously stated, I understood your point. But, if it makes you feel better to make belittling comments to someone you don't know, then have at it.

I also understand that 2+2=4. So, if the Alembic circuit isn't returning 4, then it might suggest there is a different operational aspect in play; which was my point that neither of us is looking at the actual circuit topology.

My time at Xerox PARC taught me that not knowing something can be a strength; since it informs regarding where additional investigation is required. Folks I worked with at Bell Labs and Watson were similarly inclined. But, I have also learned that much of the rest of the world misses that point, views lack of knowledge as a weakness, and is quick to pounce.

It's all good. If you're not curious how Wickersham did it, then we can just agree to move on.

 

[Kindness]

Since the classic dummy coil setup is also *not* tonally transparent and is far more cumbersome to install than a set of pickups that are designed to be hum cancelling, there's just no need.

There are the more complex setups, like the ones manufactured by Illitch are perhaps more transparent, but a rather large undertaking to install and dial in in comparison to just buying a set of nice hum cancelling pickups.I have this setup in a Les Paul with P-90's. It's pretty transparent, if I had to do it again I'd probably buy stacked P-90's instead.

I guess the short answer is we've evolved past the need for dummy coils.

I have a bass with a single coil pickup and a dummy coil on a push pull switch. I mainly prefer the single coil tone (more than the noiseless version of the pickup), but there are times I want it to be dead silent and then I put in the dummy coil.

In that context, the dummy coil is the superior option.

 

[micguy]

As previously stated, I understood your point. But, if it makes you feel better to make belittling comments to someone you don't know, then have at it.

I also understand that 2+2=4. So, if the Alembic circuit isn't returning 4, then it might suggest there is a different operational aspect in play; which was my point that neither of us is looking at the actual circuit topology.

My time at Xerox PARC taught me that not knowing something can be a strength; since it informs regarding where additional investigation is required. Folks I worked with at Bell Labs and Watson were similarly inclined. But, I have also learned that much of the rest of the world misses that point, views lack of knowledge as a weakness, and is quick to pounce.

It's all good. If you're not curious how Wickersham did it, then we can just agree to move on.

You're trying to explain how to approach R&D to someone who did it for an entire career - from college to retirement.

Have a nice day.

 

[sikamikanico]

I think it's all been said here already, but in short, my sense is that dummy coils work best with active systems. Alembic of course is the prime example, but I believe this was done similarly on Musicman basses that used the feature. Also, the Audere preamp models with the dummy coil were, of course, active.

The alternative for passive basses is the Illitch/Suhr system. I cannot recall the details of the design, but the key is to use a large diameter dummy coil. As such, it doesn't change the tonal properties of the pickup when used together. But the large diameter is its downside - to implement it best, one would typically need to route their guitar/bass. But from everything I read and heard, it works well. The idea was well understood since at least the 70s, as per Rick Turner, but of course Alembic chose the active solution instead.

So why are they not more popular? Because they're complicated and expensive to execute well. Other hum cancelling designs work well. And to many single coil purists, a little hum is either not that much of a problem, or even part of the charm.

 

[lalo_garcia-maynez]

Bass player magazine did a review of the sterling bass (music man) in 1993. I still have the magazine somewhere!
They concluded that only alembic had been able to tackle the problem correctly !
And the sterling model too …
Alembic now suggests that you upgrade the electronics on series basses to eliminate noise on their series basses . These days (with the proliferation of cell phones , WiFi , and other wireless signals ) there are more things that can cause noise and interference. So yes old Alembic series basses can be noisy these days if you don't upgrade the electronics.

 

[bucephylus]

You're trying to explain how to approach R&D to someone who did it for an entire career - from college to retirement.

Have a nice day.

No. What I just told you was that the best R&D folks with whom I had the privilege of collaboration were curious about the things they didn't understand, as opposed to what they did understand.

I had no intent to insult your knowledge, for the simple reason that I don't know you. My sole point was that neither of us knows what circuit design is used in the Alembic preamp. So, debating that design seems somewhat uninformed. That's all.

 

[logdrum]

The best hum cancelling is to actually not care about the hum.

That is my secret on my jazz. Passive Jazz bass - burpee bridge pickup favored or reggae full on neck 80% bridge for darker and subtle low mid bump

Even though I have noiseless split coils, I am in a happy place with the above jazz setting.

For strats and P90 guitars, it's just there and does not bother me. I go 2 and 4 positions if I need less hum.

But this Fishman Fluence, it is mind boggling how great it sounds in a strat. I just got a CL strat (because I converted one to a Baritone and I need a free floater and I do not want to take my old start out) and it came with the system.