Change of pickups Log Out | Topics | Search
Moderators | Register | Edit Profile

Alembic Club » Alembic Basses & Guitars » Archive: 2003 » Archive through March 15, 2003 » Change of pickups « Previous Next »

Author Message
Malachiah (yekcko)
New
Username: yekcko

Post Number: 6
Registered: 12-2002
Posted on Sunday, February 16, 2003 - 2:06 am:   Edit Post

1:Has anyone put different pickups other than Alembics on their bass?
2:can this even be done?
3:does Alembic make more than one style pickup for a 5 string rogue?
James L. Martin (malthumb)
Member
Username: malthumb

Post Number: 55
Registered: 5-2002
Posted on Sunday, February 16, 2003 - 4:13 pm:   Edit Post

I once bought a Series I where someone had swapped out the pickups for EMGs. I had the circuit restored by Alembic. It does show , however that it is possible, though I can't imagine why.
Mica Wickersham (mica)
Moderator
Username: mica

Post Number: 692
Registered: 6-2000
Posted on Monday, February 17, 2003 - 9:10 am:   Edit Post

We don't have any experience in installing other makers pickups in our basses, and like James, we've seen it done before.

We only make one pickup style for each of our basses because we dn't actually use the pickups as tone controls. The frequency response is very wide and the only thing a different pickup will accomplish is to restrict what the electronics have to work with.

This is much different from most builders' approach to pickups and electronics, but then again, most builders don't make their own pickups and electronics.

The Rogue can be fitted with an extra-wide aperture pickup, the FatBoy. We don't use this on the standard model because the pickup is so big, it takes some of the beautiful wood away. This pickup is the one on the Excel bass and the same shape as you see on the Mark King models. It offers the widest frequency response because it uses the widest magnet (same one as the Series I/II).
Joey Wilson (bigredbass)
Junior
Username: bigredbass

Post Number: 49
Registered: 9-2002
Posted on Monday, February 17, 2003 - 9:36 pm:   Edit Post

..while we're on the subject ...

Mica:

Are the FatBoys the same size as AXY5/6's ? Could I retrofit them into my 5-string Spoiler? Any problem with them and the Spoiler circuitry?

Thanks,

Joey Wilson
Valentino Villevieille (valvil)
Moderator
Username: valvil

Post Number: 68
Registered: 7-2002
Posted on Monday, February 17, 2003 - 11:21 pm:   Edit Post

Joey,

I believe the answers to your questions are yes, yes and no; I have 4 string AXY fat boys, but i've seen them on 5 & 6 strings Excels too. Rami has a bunch of 'em in the showcase section. I swapped regular AXYs for Fat Boys in my signature myself, and it was very easy; I also have them on a custom Rogue ( AXY shape too); I can't see a problem with fitting them on a Spoiler. Personally I love 'em.

Valentino
Michael Walker (rockandroller)
Junior
Username: rockandroller

Post Number: 27
Registered: 11-2002
Posted on Tuesday, February 18, 2003 - 3:58 am:   Edit Post

Mica: what do you mean when you say that the FatBoy "offers the widest frequency response because it uses the widest magnet (same one as the Series I/II)"??

My (admittedly rather vague) understanding of pickups is that they are mainly considered 'inductors', so low-frequency response is pretty much to DC, but high-frequency response gets choked off as the inductance rises...

Ergo, my interpretation of what you just said is that Fatboys actually have extended high-frequency response compared to the AXYs. (somehow the larger magnet permits you to use lower-impedance wire, and thus gain more high end?)

Is this correct?

My gleanings from the web site had led me to believe that the larger magnetic aperture merely allows the pickup to "sample" a greater patch of string harmonics - resulting in a more "complex" tone, not neccessarily extended frequency response.

If you could clarify this, it will help me greatly in my ponderings (I will make a separate post to ilustrate why!)

Alfredo (kayo)
New
Username: kayo

Post Number: 8
Registered: 10-2002
Posted on Tuesday, February 18, 2003 - 8:52 am:   Edit Post

There so much technical data being discussed here..... great to always fortify my understanding of the complexitites involved in what all has gone into the design of an Alembic.

Just a quick comment... why would ANYONE EVER want to put EMG's in an Alembic???? Isn't that kind of like going from a luxury Mansion to a trailer home? My Steinberger bass has EMG's (I only own it for portability... I can take it everywhere, the bus, the plane...) and it has decent action.. aside from that those EMG's really suck.
Dino Monoxelos (dean_m)
Member
Username: dean_m

Post Number: 65
Registered: 7-2002
Posted on Tuesday, February 18, 2003 - 11:27 am:   Edit Post

Valentino,

You mentioned you replaced your AXYs with Fatboys and had no problems? Did you notice a difference in tone and if so how much between the AXYs and the Fatboys. I might consider doing this to my Elan 5 string if it makes a significant difference. I was and still am considering sending her back to Alembic to have the quick tone switches installed. I'm just real reluctant to ship my baby cross country.
Has anyone else done this modification?!? If so please chime in!!

Thanks,
Dino
Valentino Villevieille (valvil)
Moderator
Username: valvil

Post Number: 69
Registered: 7-2002
Posted on Tuesday, February 18, 2003 - 12:13 pm:   Edit Post

Dino,

I guess the best way I can describe the sound I get from Fat boys is that tonally they are not really much different from the regular ones, but they give you a much hotter signal, resulting in a bigger sound; if you want to get a fat, saturated sound or even a somewhat distorted sound, it's easier to accomplish with the Fat Boys. I'd call it Alembic sound squared. Stoney may also have some feedback for you, since I believe he got some himself for one of his basses after he & I discussed them last year.

Valentino
Malachiah (yekcko)
New
Username: yekcko

Post Number: 7
Registered: 12-2002
Posted on Wednesday, February 19, 2003 - 12:41 pm:   Edit Post

Can anyone suggest the best strings to use on my five string Rogue, and also give me suggestions on setting up my strings for the lowest action possible without fret noise, My rouge has two trust rods adj wich makes adj my neck a real challange. Could use some help!

Thanks

(Message edited by yekcko on February 19, 2003)
Valentino Villevieille (valvil)
Moderator
Username: valvil

Post Number: 73
Registered: 7-2002
Posted on Wednesday, February 19, 2003 - 1:13 pm:   Edit Post

Hello Malachiah,

adjusting the truss rods is less complicated than you may think. When you turn them clockwise you tighten them and you get more back bow. Loosening the truss rods gives you more forward bow ; generally you do not need to tighten or loosen them much, a quarter turn will do the trick often enough. Be careful that you do not loosen them too much, or they won't have any purchase at all. It is easy to tell when they have gotten too loose as you won't feel any resistance when turning them; if that happens just tighten them back until you feel them 'bite' again.

There are several variables that determine how low you can set the action on your bass. The truss rod adjustment is one. The height of the bridge is another, your touch ( do you pluck/pick in a heavy style?) is a third and string tension is a fourth. Also, when you make adjustments to the set-up of your bass you generally need to reintonate it by adjusting the bridge saddles. Mainly it's a matter of trial and error. if you feel uncomfortable doing it yourself, find a good luthier in your area and have him set it up. Also keep in mind that if you you live in an area with dramatic shifts in humidity, you might need to readjust the bass from time to time to keep it just like you want it.

There's a bunch of good strings out there, however my favorites by far are Thomastik strings. I like both the Jazz Flats and the Jazz Roundwounds; they are quite expensive, about twice as most other makers, but they are worth it, they give you a huge tone and they are the only Electric bass strings I know of that wrap their core in silk. However due to their low tension, sometimes you need to have a neck heat bended ( nowhere near as scary as it sounds) so that you do not end up with a back bow which makes the whole bass buzz ( as I did). Other strings I like are Elixir strings and DR low rider strings. But everyone has a different taste, so a lot depends on how YOU like your bass to sound. Do you like it bright, very deep or in between?

It might be easier to give you suggestions if you can tell us what you like soundwise , how you play and how is your Rogue set-up at the moment.

Valentino
Malachiah (yekcko)
New
Username: yekcko

Post Number: 8
Registered: 12-2002
Posted on Thursday, February 20, 2003 - 6:05 am:   Edit Post

Valvi, Thanks much! yes I do live in a climate nightmare,,, Minnesota,,also, I like a Warm sound, I play gospel, so the bass must cut through the mix, I have never tried strings other that roundwounds, what kind of sound do flats give???....BTW...please comment on heat bended, what is it, how it happens, etc.....Thanks much for you respones, it helps alot!!!

Valentino Villevieille (valvil)
Moderator
Username: valvil

Post Number: 77
Registered: 7-2002
Posted on Thursday, February 20, 2003 - 9:22 pm:   Edit Post

You're welcome my friend,

If you like a warm sound then you very likely will appreciate flatwound strings, particularly Thomastiks. Their roundwounds are also fairly warm, yet they have some brightness in them too.

Heat bending the neck is something I've had done to one of my babies, but I couldn't really tell you exactly what the technique is. I guess it should not be too dissimilar from the techniques used in making the sides of acoustic instruments. I dropped it off at Alembic on a Friday and picked it up the following Monday. What I think they do is use a combination of heat ( maybe steam??) and clamps to bend the neck a little more so that it will be in the correct position when light tension strings are put on. Generally speaking, I believe that over 95 % of the bass strings out there have tensions that are fairly similar, so that even when you change gauge, no matter who made your bass, all you need to do to get the neck properly set up, is to adjust the truss rod(s) a bit. Thomastiks, as I said above, have soooo much less tension than your average string that often you do not have enough room with the rods to adjust the neck properly. Mica told me that it is something they have experienced several times before with other clients who switched to Thomastiks. Infact, I took her suggestion, so that when I commissioned my newest bass I brought a new set of Thomastiks to Alembic so that the bass could be fitted with them right at the factory. I don't believe you could find many companies that would encourage you to do that, and that's one of the many small things that in my opinion sets them apart from everyone else.

Anyways, in short, unless you plan to use Thomastiks I doubt you'll ever have to worry about having your neck go through the heat bending procedure.

Mica can most likely give you more details on heat bending necks.

By the way, you might want to re-read my previous post since I realized I had the truss rod adjustment tips reversed; it's now corrected. Sorry about that.

Valentino
Joey Wilson (bigredbass)
Junior
Username: bigredbass

Post Number: 50
Registered: 9-2002
Posted on Friday, February 21, 2003 - 11:06 pm:   Edit Post

M(y):

Like VV said, adjusting your truss rods is learned easily on your ALEMBIC. I taught myself, so believe me, you can too. A couple of tips from my self-imposed semester:

A GREAT resource is Dan Erlewine's book, GUITAR PLAYER REPAIR GUIDE, ISBN 0-87930-291-7. Most mall stores have it/can get it, or try the guitar makers' supply houses like Stewart-MacDonald or Luthiers' Mercantile. Dan really takes the mystery out of it. And he's able to make the technical theory very understandable.

ALEMBICs are very easy, with the pre-radiused bridge and the adjustable nut. With the BigRedBass, I've found I adjust the lowside truss rod separately from the high side, almost as if it were two separate basses. This is understandable as the big E and B certainly have much more tension than the G and D. And the neck-thru eliminates the neck joint.

A lot depends on how much you can feel, and your playing style. A very low action demands a very deft touch. As I learned, I got to where I could feel when the relief, height, etc., were where they needed to be for me. You'll do the same.

Of course, do this with new strings, and set your intonation/bridge saddle lengths AFTER you're finished.

I agree with VV in that the Thomastiks are very fine. The guages may seem a little strange, but they are terrific feeling and sounding strings. And, as VV said, neck re-heats are very rare for ALEMBICs.

Best of Luck,

Joey Wilson
Malachiah (yekcko)
Junior
Username: yekcko

Post Number: 13
Registered: 12-2002
Posted on Sunday, February 23, 2003 - 6:40 pm:   Edit Post

Joey and Valvi, I think you very much for your help, I seem to remember someone a while back telling that I should adj both trust rods at the same time the same amount of turns on a bass that has two trust rods, I dont know how true that is but???? BTW, is it possible that strings with taper ends will give me a little action close to the neck???

Peace and Blessings!
Valentino Villevieille (valvil)
Moderator
Username: valvil

Post Number: 81
Registered: 7-2002
Posted on Sunday, February 23, 2003 - 7:12 pm:   Edit Post

Malachiah,

generally speaking, yes you should adjust both rods at the same time, and by a similar amount (but not necessarily identical), as long as the neck is not twisted ( rare on a high end bass). As I said earlier, it depends on the tension of the strings you use and other variables. . You want to wait a few minutes ( 15 or more) after you make the adjustment, to let the neck settle, before you decide weather you like the result or not. Start with small adjustments, and see what you get. You can always mark the orgiginal position of the rods in some way, so that you can go back to the old setting if you don't like the results.

For further reference on mantaining your Alembic bass, and truss rod adjustments, check out this link. http://www.alembic.com/support/care.html

Sorry but I don't know what to tell you about the taper end question.

Valentino
Joey Wilson (bigredbass)
Member
Username: bigredbass

Post Number: 52
Registered: 9-2002
Posted on Wednesday, February 26, 2003 - 10:05 pm:   Edit Post

(M)y:

The taper-end (AKA superwound, exposed-core, etc.) WILL lower your action. How much will vary by how 'tapered' the string is at the bridge saddle. I remember the original Superwounds from James Howe really were just the core wire at that point. Most makers these days will have one wrap at that point.

But like most things in life, this 'cuts both ways':

First, this type of string can feel a lot more loose under your fret hand. And second, they can be very difficult when it comes to adjusting your string lengths at the saddles to intonate properly.

How LOW do you want your action? REALLY low?

Over time, I've come to a VERY low action. Read this check list to see what it required:

I had to learn to play very lightly, and let the volume knobs do the work. If you're really flailing at strings, stop right here.

I had to find one brand and guage of string and stay with it (Thomastiks for me), because for action we're speaking of clearances in the thousands of an inch making a difference. Still buying different strings every time you put new ones on? Stop right here. Or be prepared to re-tune all of your adjustments to cope with a different set of strings each time.

Be prepared to study and put some time in on this. There is a subtle and complex inter-relationship between nut height, neck relief, and bridge height that is gradually learned. These three values change in corresponding fashion; rarely will a change in one not affect the other two, all the while assuming that all of the frets are the same height. This isn't rocket science. But until you can learn this for yourself, be prepared to make LOTS of trips to a guitar tech.
If you're not willing to invest this time, stop right here.

BUT . . . . as I said earlier, ALEMBICs are about the easiest basses for anyone teaching themselves to adjust their necks. On MOST basses, you'd have to unbolt the neck to adjust the truss rod, and also adjust the down-angle of the neck by shimming the neck pocket. The bridge would be generic and you'd have to adjust the bridge heights separately. And if the nut was wrong, you'd have to replace it.

ALEMBICs skip all these unpleasantries. The nut is adjustable, the radius of the bridge saddles is already matched to the fingerboard curvature, and the neck is already set at the right angle.

Listen, if I taught ME to do this, ANYBODY can do it. It gives me lots of pride that I've done it, and I get a real buzz when my friends comment on how EASY the BigRedBass plays.

When you begin, I can't repeat VV's advice enough: Start with SMALL adjustments. In this business, a LITTLE goes a LONG way!

Best Regards,

Joey Wilson
Paul Lindemans (palembic)
Advanced Member
Username: palembic

Post Number: 280
Registered: 9-2002
Posted on Thursday, February 27, 2003 - 1:46 am:   Edit Post

Brothers and Sisters,
Malachiah,

what brother Joey and Moder Valentino (LOL ...moder sounds as "mother" too!) say is SO true!
Being on this board for about 7 months now (I'm from the post-yahoo-era) learned me a LOT about my bassplaying.
I say "bassplaying" in purpose and not Alembic because in my opinion it passes beyond the brand name what happens here. Things I learned here I can use as well in handling my Fender JB, as a Stagg or Hondo or Suyawacko whatever.
However ...playing an Alembic helps a lot in "bass"playing.
Let make myself clear: before meeting the people here " I hit the strings and played".
Now it's about "how can I adjust my guitar so I can get the sound that's really me".
That's a completely different concept... it's about "being Alembicious" as a bass-player.
And believe me: you can be that with a Warwick (as proves brother Dino) too!
Only: with an Alembic is easier.

The texts of Joey (and Valentino, and Michael, and Bob, and ...well the whole family here) made me change "in full consiousness" change strings from d' Addario to DR.
Oh man-oh man ... it just didn't work for me. I couldn't get the strings "right" for me. So i went back to ...d'Addario. It took me 3 (three) months (MONTHS) "to go there and back again" (I read definitely to much Tolkien these days).
The result however is that Bonnie never felt better with the d'Addario's.
Now I'm gonna make the change to Thomastik as soon as I can spend the money and give it another try again.
I will be with trial and error (oh man .... what errors!!) but I guess I wil be manage the job with more comfort and work on it with more focus and so quicker!

Listen: Alembicians are "tweakers".
They like to do "BOM" on their basses but it has to be a "BOM" with an "edge", a "BOM" with an "attitude". We like to have control and the "BOM" has to be produced under OUR conditions.

Alembic guitars and basses allow you to plunge even in the physics of your guitar (the neck-setting) when you want to create YOUR "BOM". It's not difficult but it takes time to get acustomed to that fact.
Now if you have F.i. a bass with Europa or Series electronics, you plunge into a large world of electronically shaped "BOMS".
Can you imagine the brothers and sisters adding TO THAT a F1-X or F2-B and a SF-2 also from Alembic??
You can shape a "BOM" into a "PIN" !
AUGH!!

Paul
gale barchus (gbarchus)
Junior
Username: gbarchus

Post Number: 26
Registered: 6-2002
Posted on Thursday, February 27, 2003 - 7:13 pm:   Edit Post

Paul,

Have you tried the d'addario CHROME flatwounds? They're stainless steel (meaning, not nickel) and the tension is higher than thomastic. Use the 100 E-string set (not 105). They're definitely not as warm sounding. I use them in Japan since I cannot get the thomastics. Some people hate them.

I tried the thomastics on my alembic 20th anniversary and couldn't get the neck adjusted with the truss rods completely loosened. But I love their feel and sound on my Fenders, especially my fretless.

Gale
Paul Lindemans (palembic)
Advanced Member
Username: palembic

Post Number: 282
Registered: 9-2002
Posted on Friday, February 28, 2003 - 12:01 am:   Edit Post

Hi Gale,

how are you brother in the (really FAR) East?
Good to hear from you! I DO use the 'd Addario Chrome flatwounds on my Fender JB. Even further: I use the 100's. I use them for the work with the Big_band I'm playing in. Untilk know I'm happy with those.
So you consider the Thomastik "flatwounds" to be "warmer" if I read your message well? I will try them.
The "problems" -well, not really problems but a report of how I manage to find out the DR's weren't working- were for Bonnie, my SII-5string and for that bass I use roundwounds.
I'm gonna try the Thomastik what must be not THAT problem because hey are EU-brand. Brother Mikey promised me a set of Elixirs 5 to try too! I sended him the DR-set I didn't use (by buying 2 sets I could heve a serious discount on that moment in the shop).
Keep me posted on your string experience!

Paul

BTW: I'll check some stores over here if I can find the Thomastics: price, gauges etc ... . Please let me know what you want. I know for shure that we can work something out so that I can send you some sets if you like.

(Message edited by palembic on February 28, 2003)
Werner Witzel (thebass)
New
Username: thebass

Post Number: 1
Registered: 3-2003
Posted on Wednesday, March 05, 2003 - 9:23 am:   Edit Post

Hello Alembic-Club,

since this is my 1st posting here allow me to introduce myself first. I am 40 years old and work as an electrical engineer and live nearby Cologne, Germany. I've been playing bass for 25+ years as an amateur musician in several local bands. Since I recently bought my 1st Alembic Mark King Signature I know that non of my 20+ previous owned basses has the sound and tonal flexibility of my MK Std (not to mention the fine craftmans wood work).

Regarding Alembic PUs: I always though that the Alembic PUs are low impedance type with a resonance frequency much higher (> 20kHz) than all other PU brands on the market. The special Alembic sound is also a result of the active electronics which is basically a state variable filter by which you are able to modify the resonance frequency (the Wah-Wah effect you hear when you turn the filter frequency pot). The PUs itself have no noticable soundcolor at all because the resonance frequency is too high to have any effect on the tone. In fact the Alembic circuit and PUs emulate the resonance curve of other PU brands but with the important advantage that you are able to change the resonance by the simple turn of a knob.

Thus a PU replacement of the Alembic makes no sense to me because the limited transmission characteristics of other PUs would only limit the tonal flexibility of the circuit.

Werner
Russ Carreiro (zappahead)
New
Username: zappahead

Post Number: 5
Registered: 10-2002
Posted on Wednesday, March 05, 2003 - 9:37 am:   Edit Post

I personally would see no reason for what I do to change the pickups in an Alembic. I think though, that personal preference always takes precedent over everything else. Its easy for me or you to say that its a waste, but if someone has used a brand for a long time or has latched onto a brand that they feel is "their" sound then I guess I would see their point.

I do, however, think that my answer would change depending on whether you are talking about a guitar or a bass also. I am no expert on either, I am a guitar player though, and I know of many guitarists who really just want a certain brand or a certain sound or voicing that they are used to or familiar with. I could see them wanting to change to another PU other than Alembic simply because its very hard to find any other maker of guitars who has access to all of the tone woods and expertise that Alembic has in making custom instruments. I could see them wanting the Alembic look and style and wonderfull craftsmanship, but with their own PUs that they are used to.

That being said, I like the Alembic sound and if I wanted voiced pickups or a PU brand that Im in love with, I would probably just buy another brand of guitar because I do agree that its a waste to take apart an Alembic.
Michael Walker (rockandroller)
Junior
Username: rockandroller

Post Number: 38
Registered: 11-2002
Posted on Wednesday, March 05, 2003 - 2:58 pm:   Edit Post

maybe the series pickups are Lo-Z, but the AXYs are pretty much normal impedance (i have one that measures about 8.4K ohms)

Subjectively, it sounds 'clearer' than most other pickups, and its faraday cage shielding gives it superlative noise rejection!

I have been experimenting with the AXY & filter in a 'test instrument' ( different pickup placements, heavy-duty noise testing, etc) - to help with my eventual custom order decisions, and in the course of this I played around with several other pickups in conjunction with the Q-filter. None sounded anywhere near as good as the Alembic one!
Bob Novy (bob)
Junior
Username: bob

Post Number: 26
Registered: 11-2002
Posted on Wednesday, March 05, 2003 - 4:03 pm:   Edit Post

Michael - as long as you're set up to experiment, and thinking about what to do for your custom, you should try to get your hands on a FatBoy. Same physical size as an AXY, but with a much wider aperture, and quite a few people feel they sound better.
Paul Lindemans (palembic)
Advanced Member
Username: palembic

Post Number: 293
Registered: 9-2002
Posted on Thursday, March 06, 2003 - 12:45 am:   Edit Post

Hi guys,

and in the middle of this high-technical and serious wabble I'd like to welcome a new member from my side of the pond, welcome Werner.
I like your explanation but to be honest: you are related with Bob, Joey and Michael and a few others: when they write something in a thread I immediately feels the urge to print it out, tit are really things to learn about but otherwise it doesn't seem readable to me.
;-)

Paul
Werner Witzel (thebass)
New
Username: thebass

Post Number: 2
Registered: 3-2003
Posted on Thursday, March 06, 2003 - 1:10 pm:   Edit Post

To Michael:

Sorry for using the term Low-Z as a synonym for high resonance. I didn't measure the PUs impedance (I am playing too much on my new beauty to have time enough to rip it apart ;-). The important property of the PUs is their high resonance frequency to catch every harmonic from the string. Above their resonance all PUs have a roll-off of 12dB/Oct.

To Paul:

Thanks for welcome and sorry for writing too much tech stuff here. My only excuse is my profession as an EE eng which has become second nature to me. But my passion is the bass. I don't know why but it seems to me that the connection between engineering and music is very likely. Many of my engineering collegues are musicians.

now back to bass play mode again

Werner
Joey Wilson (bigredbass)
Member
Username: bigredbass

Post Number: 56
Registered: 9-2002
Posted on Thursday, March 06, 2003 - 9:51 pm:   Edit Post

WW-

TERRIFIC to have you with us.

My favorite quote from Mica reminds us that ". . .
ALEMBIC was started by an engineer (Ron, her father) and an artist (her mother Susan). .", so
you should feel right at home. And if you're like me, when I play my ALEMBIC, that quote is confirmed by my hands and ears every time I do so.

Joey Wilson
Paul Lindemans (palembic)
Advanced Member
Username: palembic

Post Number: 298
Registered: 9-2002
Posted on Tuesday, March 11, 2003 - 11:59 pm:   Edit Post

Tag Werner,

no apologies brother. I envy people lik eyou who can actually explain what is going on electronically. Understanding is the way to mastering. Alas I REALLY have no technical mind and not quick in understanding.
Example:

Above their resonance all PUs have a roll-off of 12dB/Oct.

I don't have the faintest clue what that sentence means.
I want to learn but I guess you all have to learn to write Palembic-english = using twice the space to explain something than you should use to a normal bass-player.
LOL

Paul

BTW: I KNEW Joey would like you Werner!
Werner Witzel (thebass)
New
Username: thebass

Post Number: 3
Registered: 3-2003
Posted on Thursday, March 13, 2003 - 10:17 am:   Edit Post

Hi Paul,

Ok, so hereís the short story:
12dB/Oct roll off means that the output voltage of the Pickup drops by 12dB each Octave above the Pickups resonance frequency (the frequency where it has the highest output voltage).

No clue ? Ok, here is the long story:

A pickup (PU) mainly consists of the the magnets surrounded by a coil of mostly copper wire. Some PUs use silver wire because of the slightly reduced ohmic resistance of the wire, but that is very unlikely. This coil has an inductance (called L) which is measured in Henrys. But thatís only half the business because it neglects that the coil is non an ideal coil. The windings of the coil also have a capacitance (called C) which is measured in Farad. More likely you will see the capacitance value is expressed in micro (equals 10^-6) or nano (equals 10^-9) Farads because one Farad is a very huge capacitance. But it gets even more complicated. The resistance of the wire is not zero (unless it would be superconductive, which would require Alembics cooled down by liquid nitrogen and would make playing a bit uncomfortable). This resistance (called R) is measured in Ohms and is a series resistance to the inductance from above. If you consider all this you are able to substitute a PU with its equivalent circuit (only electrically of course) that looks like this:
figure 1
Well we are almost there but again there is a bit more. A PU is not a quite unit, right ? If you hold the PU near a plucked string you can measure a signal voltage between itís terminals. So there is also a signal voltage source which is in series to the coil wire (represented by the Inductance L and its Resistance R). Ok, letís redraw the circuit diagram:
figure 2
The signal from the strings is represented by the little circle with the wave inside and the PU is represented by its Inductance L, its Resistance R and the Capacity C between the windings.

Ok, now that you now what is the equivalent circuit of the PU what can you do with it ?

The signal from the strings in the above picture is considered as ideal which means that there is no distortion, no filtering or whatever. But this signal is only theorethically available because we need a PU (with given R, L and C) to get the signal from the strings. So if you now the values of R, L and C in the circuit above, you can calculate how the PU affects the sound from the strings. Ok, ok I know there is much more which forms the sound but lets concentrate on the electrical characteristics of the PU.

Ok, so how does it sound ?

Any Inductance L also has a Resistance (called XL) which is dependant on the frequency of the signal voltage. It doubles each octave, e.g. the Resistance at 200Hz is twice the Resistance at 100Hz. And again at 400Hz its twice as large as at 200Hz. To express this in a compressed form technicians express this with logarithmic values called decibel or "dB". A value of 6dB per Octave simply means that "something" (in this case the Resistance of L) gets doubled if the signal frequency gets doubled too. If you see something like "minus 6dB per Octave" this means that something is half of its original value if the frequency is doubled.

The capacitance C behaves exactly the opposite as an Inductance: it divides its Resistance (called XC) by two each time the frequency gets doubled.

Pooh, much math, eh ? Donít give up, we are almost there.

Look at the circuit diagram again: The Inductance L and the Capacitance C form a voltage divider from the signal voltage (coming from the strings) to the output terminals of the PU. As the signal frequency inreases, the Resistance value of L gets larger and larger and the resistance value of C becomes smaller and smaller. This results in a voltage divider which is dependant by the frequency of the signal voltage e.g. by the frequency of the strings. In this case it acts like a low pass filter. Because the inductance L causes the output voltage to decrease by 6dB/Oct (divided by two with each freqeuncy doubling) and the capacitance C does the same as well you can simply add both which results in ? Correct, 12dB/Oct. It still a lowpass but the signal decreases twice as fast as a simple lowpass. Since there are two frequency dependant components (L and C) this is called a second-order low pass with 12dB/Octave roll off.

Since the resistance of L increases with the frequency and the resistance of C decreases with the frequncy there must be a very special frequency when the resistance values of L and C are equal. This frequency is called resonance frequency (called f0). At this frequency the PU has its highest signal voltage output, it can even be larger than the input voltage ! (To understand how this is possible you need to get into complex number mathemathics but then I will be killed by all board members.) At the moment itís enough to know that above the resonance frequency the output voltage of the PU will decrease by 12dB/Oktave e.g. gets quartered by frequency doubling. The filter curve of the PU now looks like this:
figure 3

So what do you have now ?

By knowing the values of L and C you are able to calculate how the PU affects your sound. You know at which resonance frequency you will get the highest output, which basically means the PU will "colour" the sound with a filter curve. The resonace frequency of normal PUs is in the range of several kilo Hertz which you can hear very good.

The resonance frequency of low impedance Pus (like the Alembics) is very high, in the range of several ten kilo Hertz which is almost outside the audible range. The Alembic Q-Filter simulates the effect of the resonance frequency were Q is a value that determines the amplification rate at the resonance frequency. The higher Q the the higher the curve at the resonance and the more you can hear the filtering effect.

When you now change the filter frequency by turning the Q-Filter you can simulate almost any filter curve of any PU on the market which is why the Alembic PUs and Q-Filter are so flexible and versatile.


I apologise for the long story, lots of electronics and physics. I promise Iíll be more carefully next time wasting bandwith with tech stuff ;-)


Werner

Michael Walker (rockandroller)
Junior
Username: rockandroller

Post Number: 43
Registered: 11-2002
Posted on Thursday, March 13, 2003 - 10:57 am:   Edit Post

great post, Werner!

I noticed some time ago that even rather 'bright' pickups like EMGs have a resonance "spec" listed at about 4.5 Khz.

Which somewhat explains why an Alembic with the filter set to about half, still sounds "clearer" than most anything else with its tone control on full, and also why turning the Alembic filter up FULL results in a tone thats almost impossibly brite (because we are all so used to listening to those muddy Fender pickups....)

(Message edited by rockandroller on March 13, 2003)
Joey Wilson (bigredbass)
Member
Username: bigredbass

Post Number: 70
Registered: 9-2002
Posted on Thursday, March 13, 2003 - 10:11 pm:   Edit Post

Well, Paul, you were right!

Thank You, Werner. I've NEVER understood resonant frequency, vis-a-vis pickups, until reading your post.

I would like to explain myself a bit. The reason I value these discussions (including my friend Bob Novy) is that I always wanted to know WHY.

I got taken to cleaners early on, when well meaning friends said I just had to use an XYZ bass or an ABC amp," . . . because that's what so & so uses !" Of course I sounded terrible. I made myself a vow to educate myself, because the sound I heard in my head was going to come from other products. And those other products were built by professionals who all had to obey the same laws of physics as everyone else. Once I at least began to understand the language, I made progress in leaps and bounds.

--Adjusting my action was nothing like the WRONG things most people told me.

--The way to make a loud, clean, bass rig was NOTHING like most people told me.

And on and on. But when I began to ask professionals questions where they could see I was trying to be informed, the heavens opened up, and I'm in their debt. This process is repeated over and over in this forum, and the Wickershams have made themselves graciously available way beyond what most do. But there are lots of good people out there who have helped me.

Since my ears were that worrisome to me in that I could hear way too much, getting the technical hurdles out of the way allowed me to just play.
I sounded better, so I sounded better.

Joey
Paul Lindemans (palembic)
Advanced Member
Username: palembic

Post Number: 310
Registered: 9-2002
Posted on Friday, March 14, 2003 - 1:54 am:   Edit Post

***sigh***
it's "printing time" again.
So you have to be patient friends, it can take some days before I've wrestled through that Werner piece.

Topics | Last Day | Last Week | Tree View | Search | Help/Instructions | Program Credits Administration