Low-Z pickups and JFET buffers, HELP!!

[David King]

Maybe you should consider wrapping another 6-7K of wire on each pickup. There must be a reason the rest of us do it that way. Sorry, couldn't resist.

[David Schwab]

Maybe you should consider wrapping another 6-7K of wire on each pickup. There must be a reason the rest of us do it that way. Sorry, couldn't resist.

Well back when Les Paul did it he had to use a transformer... and that was about 1100 turns of 30AWG! Now we have semiconductors.

It's all what you are going after. I have one of my pickups that's 8K, and it sounds like any other 8K pickup. It's a nice sounding pickup, but there's nothing special about it. In parallel it sounds like a Ric pickup.

My 4K pickups have a much winder frequency range of any 8K pickup!

If we all wound 7K pickups, we never wound have had that wonderful moment of hearing that Stanley Clarke tone for the first time!

[radii]

David,

I know this is off topic, but please share ALL of your Alembic pickup knowledge with us ...

[Biarnel]

Sooooooooooo....
I have to admit, it was my fault. I totally screwed up the J201 layout, and I wonder how I managed to hear the bass thru the amp.

Well, now I have my stratoblaster, with no 68k resistor on the input, as David said, hooked to the pickup. After that, an Artec onboard 3way eq.
The battery is shared, switched off by the jack.
(should I use 2 batteries? I hope not!)

The bass is pretty hum-free and very nice sounding, Except when near a fluorescent light. 2 meters away, no buzz.
Is it normal?
Pickup cavity is shielded/grounded, control cavity is shielded, stratoblaster is shielded and grounded.
The coils are not yet shielded... as I wrote in a thread here, I thought it was a nice thing sound-wise. It seems I was wrong (and David told me so..).

[Joe Gwinn]

Maybe I made a mistake with the J201's pins.
How may I identify the S, G, D pins?
I assumed the G was the central, but..

Not necessarily. With any device, get the datasheet, and look at the pinout diagram. No other approach is reliable.

[Joe Gwinn]

Sooooooooooo....
I have to admit, it was my fault. I totally screwed up the J201 layout, and I wonder how I managed to hear the bass thru the amp.

Most JFETS will sort-of work up side down, and there is an amplifier configuration for each of the three possible arrangements of a 3-terminal amplifying device. One always gets gain.

[David Schwab]

David,

I know this is off topic, but please share ALL of your Alembic pickup knowledge with us ...

Well from what I've read the current stacked pickups consist of bobbins made from copper clad printed circuit board. The top bobbin has a ceramic magnet as the core. The bottom coil has an corian spacer the same size as the magnet.

They wind about 1500 turns of 40 gauge wire on each coil. They wind them in opposite directions. I think they have the two coils in series. The original Series I basses had a central dummy coil that was actively summed with the signals from the pickups. Before that they had a dummy coil for each pickup wired in series and placed inside the control cavity.

After the two coils are wired up, they are placed in a copper braid mesh for shielding, and then epoxy'd into the cover.

It's a very simple pickup design by good ol' Rick Turner. I think that man has done more for "boutique" basses than people realize. (like pretty much inventing them)

I have yet to have an Alembic pickup to examine, but I've played a bunch of the basses.

I've made 'Blaster based buffers for a customer that put some Alembic pickups in a bass and he said that worked real well. Apparently Alembic sells cosmetic seconds of their pickups pretty damn cheap.

Quote from Rick Turner from the MIMF forum. Notice he invented the Suhr dummy coil system here?

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.

Here's the Alembic Factory Tour

This is Tony and he will be assembling, winding, wiring, testing and casting the pickups for the various models of instruments. He starts with cutting the copper clad phenolic board that is used in making the "bobbin" for the stacked hum canceling pickup. He will assemble the parts so that there is a piece of board then the magnet another piece of board then a corian dummy core then the final copper clad board. This will form the bobbin for the copper wire to be wound on. There are an equal number of turns on the top and bottom wound in opposite direction to create the hum-canceling effect. The pickup is tested for continuity, this is to make sure no breaks have occurred in the winding and sealing process.

Tony now has completed shielded the pickup up in a copper wire mesh cage. He has wired them with a shielded coaxial cable and attached the mini- plug containing gold plated contacts. He will test them again for continuity before placing them in the pre-stamped plastic shell and casting them in epoxy. They will receive another test for microphonics, then placed into inventory.

[radii]

Thanks David

Printed circuit board as a bobbin ? I don't understand why and how they would be using it. Maybe just leftover-thrash recycling ? Strange ...

With such a low-impedance coils, the pre-amps and general hum-suppression must be quite good.

I own an Alembic bass (Mark King model from the mid 80's ), the typical Stanley Clarke sound has eluded me however
His sound was and still is truly awesome I think (listening to Silly Putty right now )
How the low-impedance coil influences his sound however, I'm not certain. There seems to be a good amount of midrange, but then again it might be high-mids . I just can't tell ....

By the way, am I the only one to think, that he peaked creatively at the beginning of his career ?

[David Schwab]

Thanks David

Printed circuit board as a bobbin ? I don't understand why and how they would be using it. Maybe just leftover-thrash recycling ? Strange ...

Well the copper on the PCB would work as extra shielding. It's actually a good material to use. I use it all the time, especially the non copper clad perf board. They used to use acrylic plastic.

With such a low-impedance coils, the pre-amps and general hum-suppression must be quite good.

My experience is by the time you boost the signal up they hum as well as high impedance coils... though they are smaller which helps.

They achieve their noise cancellation though shielding and the dummy coil.

I own an Alembic bass (Mark King model from the mid 80's ), the typical Stanley Clarke sound has eluded me however
His sound was and still is truly awesome I think (listening to Silly Putty right now )

Well it's more than the bass for sure! I used to play Rickenbackers, and I never got them to sound like Chris Squire or Paul McCartney!

But for the Stanley tone you need the same strings (brand new set of Rotos), an Alembic preamp, and his fingers! I think he has the filters wide open, but I don't know how he has the resonance set.

On Silly Putty he has his action really high. It was so high that he said he had a hard time playing it. You can hear him make a small flub in the beginning. He likes high action for slapping to get a cleaner tone with more lows. And don't forget the Clarke bass is a short scale. The King model is a long scale.

Every now and then I can get the Stanley tone if I pluck really hard and roll back the top end on my bass with a low pass filter to give that woody snap. Alembic filters have a ceiling on the highs. You never hear the total range of the pickups. I've read they feel it's not all that musically useful.

How the low-impedance coil influences his sound however, I'm not certain. There seems to be a good amount of midrange, but then again it might be high-mids . I just can't tell ....

Low impedance coils have a wider frequency response, especially in the high end. They are also very flat. The resonant peak that occurs before the frequency starts to drop off is much higher than with high impedance pickups, so it can be pretty much out of hearing range. So you don't get that upper midrange hump that most pickups have.

This was Alembic's idea with using low pass filters. By rolling the cutoff frequency down a bit, and inducing a peak with the Q switch, you are kind of simulating a high impedance pickup. I say "kind of" because I think that's a but too simplistic, but it does simulate a load on the pickup.

You hear more mids and highs because they are more present, and the lows are not as accentuated as on Hi-Z pickups. I get more of a low end presence by making low Z humbuckers rather than the single coils.

Here's my latest design using neo magnets. Neo Bridge

By the way, am I the only one to think, that he peaked creatively at the beginning of his career ?

I think the newness wore off, as well as the whole fusion scene. People have to make a living though, and he's done very well doing sound tracks. But that raw energy is gone. I last saw him live for the School Days tour. That was good stuff!

Now Mark King is another killer bassist! He gets a very different tone too. Those really light gauge strings.

Speaking of legends, I saw Robert Fripp & the League of Crafty Guitarists last Thursday. It was a great show! It was mostly the League playing, while Fripp sat there, but he did some great soundscapes and played along with them on some tunes. He looks like a grandfather now. Crimson will be touring nest year.

[radii]

Ahh, Mark King !

I just watched a few Level 42 clips on YouTube, and I'm not certain what to think. I used to love the guy, about 15 years ago ...
Now however, I find his playing, especially current footage with him soloing, to be quite annoying. The older stuff is still pretty cool however ( nostalgia ?). I give him total credit for doing his own thing more then 25 !! years ago, singing and playing at the same time, writing songs, fronting a band etc. I guess I was just hoping for more of a deep pocket in his playing, a little older and a little wiser maybee

He definitely got his best sound in my opinion when he played the Alembic

http://www.youtube.com/watch?v=sS9NIDOtoYw


It has somehow got that "hollowness" in the high-end, similar to Stanley Clarke's sound.

To bring it back on subject, Low-Z pickups with a buffer, seem to be the way to go

[David Schwab]

It has somehow got that "hollowness" in the high-end, similar to Stanley Clarke's sound.

To bring it back on subject, Low-Z pickups with a buffer, seem to be the way to go

I have some live mark King track, "Mr. Pink" with a solo at the beginning. I think he sounds pretty hot! I'll have to check out that video link tomorrow.

I love that hollow Clarke tone. I got a little of that in my new pickup...

Check out this track. I started with the neck pickup, then switched to both (when the guitar "solo" comes in), and then to the bridge. The bridge pickup is my new one with neo magnets. Kind of gets that hollow snarl.

Bass Head

[radii]

Just to clarify, the Youtube footage is what I consider his good playing/sound. The machine-gun slapping is in another video. You can't miss it if you youtube him ...

Your neck pickup sounds surprisingly good for slapping, and yes, albeit a little thin for my taste ( I prefer both pu's on almost ALL the time anyway ), the neck pickup has some of that " bell " sound to it.
My Alembic Mark King Model doesn't sound anything like it. Go figure ...
And I am not SUCH a horrible player Maybe really thin strings, 030 - 090 ?

Tonight, I will hopefully have the chance to play an Alembic Series II bass from the late 70's. I'll see if the Series II electronics alone are really worth about 10'000.- $

I have always thought that true stereo would be cool, but then again I really like both pickups in series. Hey, I'm a simple man with simple needs

[frank.clarke]

FETs vary a lot, you may have to fiddle with drain resistor values. J201 have lots of gain usually.