Signal paths - bass/treble controls w... Log Out | Topics | Search
Moderators | Register | Edit Profile

Alembic Club » Alembic Basses & Guitars » Archive 2006 » Archive through February 09, 2006 » Signal paths - bass/treble controls with Q's & filters « Previous Next »

Author Message
terryc
Junior
Username: terryc

Post Number: 48
Registered: 11-2004
Posted on Monday, January 23, 2006 - 6:12 am:   Edit Post

Having looked at 'Factory to Customer' forum there a few basses with mutiple tone shaping controls so here is my question to all and the people at Alembic.
Does the signal path go from the PU's to the bass & treble controls then to the Q controls/switches and tone filters or is it the other way around and does it affect the tone in either wiring arrangement.
Could a switch be used so you can select either bass/treble controls or the Q/filter arrangement or both on at once, series or parallel(I bet that will be noticed to anyone deciding on their next custom!!!!)
Trouble is it may begin to look like a strip on a mixing desk!!
Thoughts anyone????
davehouck
Moderator
Username: davehouck

Post Number: 3047
Registered: 5-2002
Posted on Monday, January 23, 2006 - 7:37 am:   Edit Post

I seems to me that the choice of signal path would affect the tone. However, I've only had one cup of coffee this morning and it's hard for me to visualize the shapes of the frequency curves.

For instance, if the filter is first and you back it off a bit and then the filter is followed by the treble control which you then boost, then depending on where the filter is set, you would be boosting frequencies that are being rolled off. (If I remember correctly, the roll off is 8dB per octave.) In the opposite configuration, you would be rolling off frequencies that had been boosted. I think in those two examples the shapes of the resulting curves would be different.

If I remember correctly, the East Meets West setup has the filter first and then the bass and treble controls. But my memory is not highly reliable.

My guess is that on a custom order you could have it routed either way; and it would also be my guess that if you wanted a switch added to change the routing, that would be possible.
terryc
Junior
Username: terryc

Post Number: 49
Registered: 11-2004
Posted on Monday, January 23, 2006 - 8:54 am:   Edit Post

Obviously you own one of these basses with the said configuration..do you think it is overkill to have so many control options..bass & treble AND the filters..it sounds like by your explanation that it is lose one lot gain another..I suppose the circuit switching would be useful.
davehouck
Moderator
Username: davehouck

Post Number: 3048
Registered: 5-2002
Posted on Monday, January 23, 2006 - 10:12 am:   Edit Post

I have a bass with Europa controls, but not one with East Meets West controls. Whether it is "overkill" or not depends on each individual's preferences; and it can also depend on how that individual intends to use the instrument. For instance, for a bass that is primarily going to be used on stage, it might be more practical to have the quick change switches of a Europa; but for studio work it may be more useful to dial in a more precise tone with the bass and treble controls instead of switches.

After my first post I had a second cup of coffee and thought about it some more and decided that I have no idea how much difference there would be having the bass and treble controls before the filter rather than after. The series/parallel switch could be interesting; but I have no idea how useful it would actually be. And the either/or switch might be useful; however if the bass and treble controls are at 0 (middle, no boost or cut) then they are essentially off, and if the filter is all the way open with no Q switch boost then it is essentially off. The either/or switch would then just reduce to one flip of a switch a choice of two settings that might otherwise take two or three movements to complete.
adriaan
Senior Member
Username: adriaan

Post Number: 720
Registered: 6-2002
Posted on Monday, January 23, 2006 - 10:16 am:   Edit Post

It would seem to make even more sense (at least to me) if the two would work in parallel, and the two signals were blended after the fact. But then why is there no blend pot?

As there is little point in being able to boost frequencies that have already been cut, and also that the filter can be used more in the sense of a colour additive, I would guess that the bass/treble controls come before the filter.

Anyway, EMW is different from the Europa/Rogue packages in that it has cut/boost pots instead of switches, so it is more flexible. On the other hand, I'm not sure whether it uses the single preamp that we associate with the Epic/Orion package, or the dual preamp that you get with a Europa/Rogue.

Ah, questions, questions ...
gare
Advanced Member
Username: gare

Post Number: 323
Registered: 11-2003
Posted on Monday, January 23, 2006 - 10:27 am:   Edit Post

Terry
No, it's not overkill. I have an Excel with the EMW electronical pkg. It's actually quiet handy..used judiciously.
Set your sound using the filter and Q switch, tweak it more with the amp. Then use the active treble and bass controls to make adjustments on the fly as needed without loosing your original sound. In small increments of course, otherwise it has the tendency to overdrive most preamps.
Gary
keith_h
Advanced Member
Username: keith_h

Post Number: 316
Registered: 2-2005
Posted on Monday, January 23, 2006 - 1:21 pm:   Edit Post

I also have the EMW package in my fretless Orion and love it. Like Gary I set my tone controls to the mid-point detent and then adjust the filter to the sound I want. After this I adjust the bass and treble controls to get the overall tone I require for a song. Yes, it is quite easy to overdrive the rig's preamp by turning everything all the way up.

I took a look inside and see one pot for the volume. There is a pot on the filter but it has been taped over. I assume it is a volume control but has been set to the appropriate level for the preamp in the bass. In any event tape means don't touch so I will leave it alone.

I can't tell whether the tone or filter comes first as all of the wiring goes to the preamp board.

Keith
bob
Senior Member
Username: bob

Post Number: 566
Registered: 11-2002
Posted on Monday, January 23, 2006 - 2:51 pm:   Edit Post

For the electronics we're discussing here, I don't believe it matters whether the tone controls are applied before or after the filter. For any given frequency, boosting by X and then cutting by X gets you back to the same place as doing them in the reverse order. If the filter were more of a brick wall, then it would be different, but I'm pretty convinced in this case the changes are simply additive.
-Bob
bigredbass
Senior Member
Username: bigredbass

Post Number: 582
Registered: 9-2002
Posted on Monday, January 23, 2006 - 3:19 pm:   Edit Post

Here's where my being pretty ignorant electronically as to what goes on 'under the hood' comes in handy.

If I dialed in a tone with the bass and treble cut/boost, THEN ran it through the Q . . .

. . . it just seems like that would sound different than setting a tone with the Q and tweaking it with bass and treble cut/boost. . .

. . . since in each case I was dealing with a different tone where I handed it off from one to the other.

If I ran a bass through a rack to a parametric THEN through a SuperFilter, I KNOW it would sound different than running it through the SuperFilter, THEN thru the parametric.

Or is it just me?

J o e y

(Message edited by bigredbass on January 23, 2006)
gare
Advanced Member
Username: gare

Post Number: 324
Registered: 11-2003
Posted on Monday, January 23, 2006 - 3:22 pm:   Edit Post

Keith
I saw the tape in mine too..aren't you dying to peek underneath it ?

I'll have to go along with Bob, at least the perceived effect is additive.
gare
Advanced Member
Username: gare

Post Number: 325
Registered: 11-2003
Posted on Monday, January 23, 2006 - 3:36 pm:   Edit Post

Its not just you Joey.
If it runs thru the filter first, which is basically at low pass filter. Once set, it would restrict the 'program material' to a certain frequency range. At that point the active controls can not boost or affect frequencies already removed by the filter at it's cutoff freq.. IE: if you set up for a low thumpy sound by setting the cutoff low, the treble control would only act like a 'presence' control since most of the highs have been filtered out.
Dat make sense ?
G
davehouck
Moderator
Username: davehouck

Post Number: 3054
Registered: 5-2002
Posted on Monday, January 23, 2006 - 6:06 pm:   Edit Post

But Gare; Bob's arguement seems to make sense also. In your example if you reverse the ciruit so that the treble control is first followed by the filter which is as you said "once set", isn't the treble control still going to "act like a presence"? <g>. Both Bob's and Joey's arguements seem to make sense to me!

Why is there tape on the trim pots???
keurosix
Junior
Username: keurosix

Post Number: 21
Registered: 10-2005
Posted on Monday, January 23, 2006 - 7:47 pm:   Edit Post

2 Cents:
I have to agree with Bob. Both Q filter and Bass & Treble controls affect the final sound regardless of order because the output is mono. There would be no way to separate the different controls from the signal path without ripping and tearing (ouch!), so they are in effect working "interactively". It would be nice to be able to insert one before the other or vicea versa, but that would only be possible after the signal exits the guitar, like in Joey's comparison. However, the Bass and Treble control could be looked at as "broad" overall sound controllers, and the Q filter could be seen as a "fine-tuning" enhancer, or "Character" control. The effect is similar to Series 1 or Signature electronics where 2 filters work together to enhance the overall sound. Example: A "broad" (high filter setting to allow more freq through) low-boosted Bass Q filter combined with a tighter (low filter setting for a mid range peak) highly boosted Treble Q filter setting. For this custom circuit, you actually would get 3 variables with the Bass & Treble acting as 2 "Broad" sound modifiers, and the Q filter acting as a fine-tuning enhancer. Hummm..
Maybe I WILL consider this for my next custom order!
Kris
bob
Senior Member
Username: bob

Post Number: 567
Registered: 11-2002
Posted on Monday, January 23, 2006 - 9:46 pm:   Edit Post

The filter does not "remove" frequencies above the "cutoff" setting - it just rolls them off at some fixed slope (12 dB per octave for the low pass on the instrument, I think). Meanwhile, a typical shelving tone control (ignoring the slope where it kicks in) cuts or boost everything above/below some fixed point, by a fixed number of dB, often by a max of about 8-10 dB or so.

So you just take the two curves, for the filter and tone control effects, and for any given frequency, add up the two values to figure out what the resulting output will be. The order doesn't matter.

Now... I will grant that in reality, you may hear some differences if you take a signal that is already down 24 dB, and try to boost it by 8 dB (for example), rather than boosting it first and then rolling it off with the filter. But this is only relevant if noise/distortion/low signal losses/etc. are creeping into the picture. And in practical terms for these instruments, the filter slope is really only relevant for a very small number of octaves anyway, so we aren't losing that much. We discussed this in the process of designing the circuit for my custom, and the bass/treble pots are the very last thing before the output jack.

It may also be worth noting that this is really only relevant for a treble control anyway, given that the usual bass control will operate well below the lowest cutoff frequency of the filter. And in the treble region, the sharp Q spike you can get with the filter is likely to dominate your tone anyway (though again, a treble control will still raise or lower that and everything around it).

I'm not quite sure I understand the comment, "because the output is mono". That isn't what determines whether the effects are simply additive. However, in practical design terms, it is certainly simpler to apply bass/treble switches or pots, after summing the output from the two pickups and possibly filters. This way you only have one signal to modify, though of course if you wanted separate bass/treble controls for each pickup, you would need extra circuitry and could it before or after the filters.

Why is there tape on the trim pots???
the_8_string_king
Member
Username: the_8_string_king

Post Number: 71
Registered: 9-2005
Posted on Monday, January 23, 2006 - 11:42 pm:   Edit Post

My custom Europa has 6 tone controls per pickup; each pickup has a filter, a 4/8/12 db Q switch, another toggle that chooses between filter off/filter on without Q/filter on with Q, bass and treble knobs (+/- 12 d) and a mid-range "quick change" toggle (+/- 6 db).

I'm frankly ignorant of most the technicalities. But I do know from experience that for me, these controls are worth having, and are not overkill. They work extraordinarily well.

The treble boost works when the filter has the treble filtered out; but it isn't as strong as it would be without the filter.

The fact is that it IS sometimes useful to use the treble boost while the filter and Q are emphasized elsewhere. The filter is the primary tone control. I'll often use it (and the Q) in say the lower mid range... so I CAN'T (simultaneously) use it in the treble range.

Having a stereo bass with individual processing, and where each pickup has an eq AND a versatile filter and Q system is the ultimate.

It works VERY well, clean sound, quiet, and very efficient.

As one of those people you mentioned with "multiple tone-shaping options", I thought I'd give you my input. If you're interested in further input, I have some pretty cool ideas as far as having a simple and compact but extremely versatile combination eq and filter/Q system -based on my custom and my Elan with Europa electronics.
terryc
Junior
Username: terryc

Post Number: 50
Registered: 11-2004
Posted on Tuesday, January 24, 2006 - 1:05 am:   Edit Post

Phew!!!..looks like a pretty complicated thread here!!..
I wonder if Alembic use a mid range control for even further tone modification then there is your amp to contend with!
I was told by Mr Wickersham(mentioned in another thread) that all is needed with his circuits is a good quality power amp with only a gain control and a equally good quality speaker cab. I agree as I set everything flat on my amp and just use the controls on my bass and I only have vol, pan, filters x2 and single Q switches...I wonder what it would be like with all those combinations.
Well I could go the other way..imagine if there was on control which did it all.
Has Alembic ever made a bass with one PU vol & tone and Alembic 'Precision' if you will all humour me please(I didn't mention the F word)
adriaan
Senior Member
Username: adriaan

Post Number: 722
Registered: 6-2002
Posted on Tuesday, January 24, 2006 - 1:22 am:   Edit Post

Not sure if they were done in any big numbers, but I seem to remember pictures of Persuaders with a single split p/u, and the low-pass filter. Also, the early Distillates made for the Japanese market had a single AXY - but with with the low-pass filter plus the quick tone switches ...
keith_h
Advanced Member
Username: keith_h

Post Number: 317
Registered: 2-2005
Posted on Tuesday, January 24, 2006 - 4:01 am:   Edit Post

Dave,
"Why is there tape on the trim pots???"

There is only tape on one trim pot. Inside the cavity there is a preamp with an exposed pot. This one adjusts the maximum volume.

The filter that is added by EMW also has a trim pot but it is taped over. This filter is wired to the preamp board. I really don't know what it is for. I assume it controls the output of the filter
and has been set to a level appropriate for the preamp.

Keith
gare
Advanced Member
Username: gare

Post Number: 326
Registered: 11-2003
Posted on Tuesday, January 24, 2006 - 7:24 am:   Edit Post

Dave/guys
ALL these arguements make sense.
I could have choose my wording better, instead of 'restrict' or 'remove' a better word would be 'attenuate'. which is really what the filter does at whatever the slope is designed for, 6/12/24 db's. I'm by no means an electronics expert, my experience comes from messing around with synths and building a modular synth (a work in progress).
The previous lenghty thread about instrument frequency range and filters explains it alot better.
I don't really know the order of the filter and active controls in these setups, it may be pararell, but it is additive, prehaps Mica or Val could shed more light on this.
I wonder if the tape in there is like the tag on a mattress..
bigredbass
Senior Member
Username: bigredbass

Post Number: 591
Registered: 9-2002
Posted on Tuesday, January 24, 2006 - 8:43 am:   Edit Post

I'm surprised about the tape as well . . . most everything around here goes straight to hard disc.

J o e y
adriaan
Senior Member
Username: adriaan

Post Number: 727
Registered: 6-2002
Posted on Tuesday, January 24, 2006 - 8:59 am:   Edit Post

Okay, I laughed. Out loud, even. Good one, Joey!
mica
Moderator
Username: mica

Post Number: 2998
Registered: 6-2000
Posted on Tuesday, January 24, 2006 - 11:36 am:   Edit Post

When you're multiplying, it doesn't matter which one comes first, 5x2=10 and 2x5=10. So the short answer is it doesn't matter which function comes first in our circuit since the functions act to multiply eachother.

In the case of the EMW electronics, since we use our standard modules to build them, there's a preamp on both the filter and the bass/treble module. We turn one down all the way (unity gain) and place the little dot over its trimpot to suggest you use the other trimpot when adjusting the gain of the system.
gare
Advanced Member
Username: gare

Post Number: 328
Registered: 11-2003
Posted on Tuesday, January 24, 2006 - 1:35 pm:   Edit Post

Thanks for the clarification Ms.Mica.

I work with a few people who could take that equation and come up with a different conclusion..I've developed a bad disc in my neck from constantly shaking my head !
kmh364
Senior Member
Username: kmh364

Post Number: 1664
Registered: 9-2003
Posted on Tuesday, January 24, 2006 - 2:44 pm:   Edit Post

Wow! Good thing only one stage contributes gain! EMW electronics can overdrive just about anything out there with only one gain stage...crank-up the other one and fuzz-bass yourself silly! LOL!

Other than re-attaching a loose modular connector and replacing the OEM battery upon initial delivery of the "Son of EMW" Orion, I haven't ventured beyond the brass cavity plate(s). Thanks to the other EMW owners for the primer.

Thanks for the clarification, Mica. This thread was working itself up into a fine lather.
bigredbass
Senior Member
Username: bigredbass

Post Number: 593
Registered: 9-2002
Posted on Tuesday, January 24, 2006 - 3:47 pm:   Edit Post

5 x 2 . . . anyway, what's an EMW? Where'd the tape come from? I'm SO confused . . .

J o e y
kmh364
Senior Member
Username: kmh364

Post Number: 1665
Registered: 9-2003
Posted on Tuesday, January 24, 2006 - 3:59 pm:   Edit Post

LOL!
keith_h
Advanced Member
Username: keith_h

Post Number: 318
Registered: 2-2005
Posted on Tuesday, January 24, 2006 - 6:30 pm:   Edit Post

Joey,
Just think analog. No slipped disks that way. Right Gary?

Keith
bigredbass
Senior Member
Username: bigredbass

Post Number: 594
Registered: 9-2002
Posted on Tuesday, January 24, 2006 - 7:23 pm:   Edit Post

E lectro M agnetically W arped? The truth!?!

The truth?!?!? You can't HANDLE the truth!

But I've got the tape.


J o e y
bob
Senior Member
Username: bob

Post Number: 568
Registered: 11-2002
Posted on Tuesday, January 24, 2006 - 10:05 pm:   Edit Post

But the tape has gaps...
terryc
Member
Username: terryc

Post Number: 51
Registered: 11-2004
Posted on Wednesday, January 25, 2006 - 12:45 am:   Edit Post

what tape??? what EMW, which control do I turn now..too much to take in..may have to go back to F Precision...aarghh!!!!!!!!!!!!!!!!!!!!
losing it over this thread..pass me the Prozac
gare
Advanced Member
Username: gare

Post Number: 329
Registered: 11-2003
Posted on Wednesday, January 25, 2006 - 6:10 am:   Edit Post

Yer confused ?
I think 5 x 2 is a nomial size, comes from an-alog.
Lets take that tape, cut er into lil pieces, toss it in the air, paste it back together..might sound ok.
Good point Keith..I'll use that one next time I cant make chiropractor appointment.
I vote for Joeys terminology..has a nice ring to it.
It's early, no caffine yet..think I'm going to rip out all the stuff in my bass's control cavity and run straight from the pickups to the amp, which I'll modify to just have a volume control..I'm feelin a need to simpilfy my life lately.

Gary
kmh364
Senior Member
Username: kmh364

Post Number: 1666
Registered: 9-2003
Posted on Wednesday, January 25, 2006 - 6:10 am:   Edit Post

Just my two cents:

I have both EMW and Series (I) electronics and an SF-2.

Getting back to the question as to whether the relative complexity of Alembic tone-shaping controls (i.e., filters) is/are overkill is a matter of perspective.

If you are from the "set it and forget it" crowd, then Alembics are not for you. Depending on the electronics package, Alembics are amongst the most versatile instruments out there tonally. That flexibility comes with a price: repeatability of settings on any Alembic (with the possible exception of the Europa switches) is frustratingly difficult at best.

Passive stuff (of which I mostly own) is easy...volume off or all the way up and tone controls wide open (unless you need a jazz guitar tone). On a Strat, for example, your "real" tone control is the 5-position p/u selector, LOL! Since attenuating volume on a passive instrument loads the p/u's, frequency response suffers, so I don't bother. Yes, I know you can add a cap (or a blaster), but bear with me here, LOL! Passive tone controls with their subtractive effects are equally useless to me. A passive instrument sounds as good as it gets with everything wide open...tweek knobs and the sound goes downhill from there. They are easy to operate though, LOL!

Bottom line of my diatribe: You gotta give something to get something! Alembics are superior, IMHO, to just about anything out there. The BUT is that you gotta love to tweek knobs in order to find that holy grail tone(s) on an Alembic. Add to this that active filters do not necessarily behave in a manner that is intuitive can be very frustrating. Anybody that owns a Series or has a SF-2 knows what I mean, LOL! The plus in all this is that it's hard to get a bad tone out of an Alembic. Finding "the" tone or tones that you need or want, however, can be frustrating and duplicating same can be an exercise in futility.

I'd add that Alemic's active stuff allows you to set and forget your amp (once you adjust for the room) and then you can go silly and controll everything directly from the instument. On passive stuff, the tone shaping on the instrument is sheisse, so I have to continually tweek the amp in order to get the sound(s) I need.

Cheers,

Kevin
davehouck
Moderator
Username: davehouck

Post Number: 3064
Registered: 5-2002
Posted on Wednesday, January 25, 2006 - 7:39 am:   Edit Post

I'm guessing the tape is mil-spec.
terryc
Member
Username: terryc

Post Number: 53
Registered: 11-2004
Posted on Thursday, January 26, 2006 - 2:42 am:   Edit Post

Kevin
All makes sense to me..passive does suck..a bad compromise at the best of times and it is an apprenticeship learning all the tone functions on an Alembic but once learned they are a joy to use..I cannot vouch for the guitar side but the basses(their forte) are the dogs gonads.
Alembics are quiet(electronically), sound great, play great and look the biz..but at a cost but you pay for what you get
terryc
Member
Username: terryc

Post Number: 54
Registered: 11-2004
Posted on Thursday, January 26, 2006 - 2:43 am:   Edit Post

whoa..I have jumped from junior to member..me at the tender age of 48
george_wright
Member
Username: george_wright

Post Number: 58
Registered: 3-2005
Posted on Thursday, January 26, 2006 - 10:41 am:   Edit Post

Dude! I was a junior at 61!
terryc
Member
Username: terryc

Post Number: 59
Registered: 11-2004
Posted on Tuesday, January 31, 2006 - 6:48 am:   Edit Post

Ah yes George..with age comes wisdom, cheap bike insurance & crap eyesight..once left my reading glasses at home and couldn't see notes on manuscript..had to borrow a pair from lady in the audience..should increase the rastral size on the printer but then you end up with 20 pages of bass stave for a three minute song.

Right..any conclusions on this signal path thing then or just use our ears which is really the best way!!!!
keith_h
Advanced Member
Username: keith_h

Post Number: 324
Registered: 2-2005
Posted on Tuesday, January 31, 2006 - 7:09 am:   Edit Post

Based on Mica'a update on the 24th it doesn't make any difference as both sets of controls are multiplicive.

Keith

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