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DIY Stompboxes => Building your own stompbox => Topic started by: will queue for free stuff on August 24, 2010, 07:19:13 PM

Title: Tailoring circuits to suit active pickups
Post by: will queue for free stuff on August 24, 2010, 07:19:13 PM
First of all, I just wanted to say thanks. There's a wealth of information here, thanks to everyone who has taken the time
to share their ideas. I've breadboarded half a dozen circuits at least, had a blast altering them, (nothing original I'm sure)  and gotten some really great results.........
well they sound good to me anyway.
There's one topic I haven't seen allot of information about.
Is there some way of tailoring a circuit to suit active pickups?
I have a Gibson w/ active EMG's and an 18 volt mod and a 20dB boost, and a Gibson w/ low output 59's.
I've noticed the EMG's beginning to clip, where the 59 model is fine.
How can I get the benefit of the active pickups? The only solution right now is to turn the volume on the guitar down, and, you know....... that just ain't right. :-\
I'm getting the clipping in most circuits I've tried, the only one I can remember that didn't was the buzz box. Then again, the fuzz is so extreme, maybe it clipped and I couldn't tell.
The input cap for the buzz box is a 10uF electrolytic. If a larger cap solves the problem, how do you avoid the sound becoming muddy?
Anybody have any ideas?   Thanks again.

Title: Re: Tailoring circuits to suit active pickups
Post by: alanlan on August 24, 2010, 07:37:29 PM
Well, 18 into 9 just won't go...  If you want to run your signal path at such high levels then it has to have the headroom to do it.  That excludes most commercially available pedals.  I'm not sure what the real benefit of active pick-ups is anyway other than being able to more heavily overdrive anything in its path or be able to driver longer cables etc.
I'd have the 59 pick-ups any day.
Title: Re: Tailoring circuits to suit active pickups
Post by: petemoore on August 24, 2010, 07:56:57 PM
  Yupp...had same scenario long ago [9v operation], Boss and Marshall Artist amp distortions chokeagged at the full on - 8 settings of EMG output. Very nasty rail-hit-tone, unmistakable, intractable.
  Turning down the only thing between the pickups and the next thing: guitar volume was deemed insufficient help, the guitar immediately abandon them.
  Maybe a coil [see AMZ labs notebook] as possible workaround, erm?
  The pickup exchange program at Lentines recieved the returned EMG's [within a couple hours of my toting them out of there] and I selected from behind the counter some high quality HB pickups [JB and another SD model, IIRC].
  For effects some [strongly] prefer working with a raw, untreated [except usual, passive V/T controls] mag/coil output.
Title: Re: Tailoring circuits to suit active pickups
Post by: Quackzed on August 24, 2010, 08:04:43 PM
you could build an "active pickup matcher". which in my mind would just be a volume control in between 2 jacks in a box.
that way you can keep your guitar on 10 and just dial down the max volume going into whatever is next... i'd guess that the actives can handle the volume cut without any tone loss or treble loss ...
Title: Re: Tailoring circuits to suit active pickups
Post by: petemoore on August 24, 2010, 08:16:57 PM
  Choose a resistor, put it on the volume out wiper or input of next thing.
  Trying it at 9v...can't you just jumper one of the battery clips ?
Title: Re: Tailoring circuits to suit active pickups
Post by: will queue for free stuff on August 24, 2010, 08:53:34 PM
Gil said;
Quote from: Quackzed on August 24, 2010, 08:04:43 PM
you could build an "active pickup matcher". which in my mind would just be a volume control in between 2 jacks in a box.
that way you can keep your guitar on 10 and just dial down the max volume going into whatever is next... I'd guess that the actives can handle the volume cut without any tone loss or treble loss ...
That's a great suggestion, I'll try that.
I see active pickups aren't all that popular, judging by the responces so far. I've found the "potential" amplitude of the AC signal provides room for
expression I haven't found elsewhere except maybe dimebuckers came close. The 18 volt mod, to my ears, adds to the warmth of the tone.
Pete said;
Quote from: petemoore on August 24, 2010, 08:16:57 PM
  Choose a resistor, put it on the volume out wiper or input of next thing.
  Trying it at 9v...can't you just jumper one of the battery clips ?
I'd really like to keep the 18v tone if I possibly can

Thanks for the quick responces.                                                              Craig
Title: Re: Tailoring circuits to suit active pickups
Post by: petemoore on August 24, 2010, 09:31:55 PM
  I love my EMG's just works out right for some, not for others.
  The input expects 'something', if what it gets is more than that, things can get ugly.
Title: Re: Tailoring circuits to suit active pickups
Post by: Paul Marossy on August 25, 2010, 10:13:04 AM
Quote from: alanlan on August 24, 2010, 07:37:29 PM
I'm not sure what the real benefit of active pick-ups is anyway other than being able to more heavily overdrive anything in its path or be able to driver longer cables etc.

Quieter, clearer, louder and less noisy than passive pickups.
Title: Re: Tailoring circuits to suit active pickups
Post by: ghostsauce on August 25, 2010, 10:25:58 AM
I've got an 81 in my warlock running on 18v and it sounds nowhere near as good as my prs with #7's.  But I think a lot of that is the guitar... maple bolt-on floatingtrem VS mahogany neck-thru stoptail bridge. PRS weighs about twice as much too XD.  The 81 sounds really really thin to me and I have to re-EQ like crazy to get it to sound right, so more often than not I just don't use it. More often than not, when I hear somebody playing with emgs I just don't care for the sound. Maybe I'm just getting old, but passive seems to win for me even for metal, and especially for rock.

Anyways, about the 18v into your pedals.. Uh... I've never noticed a difference. Am I that much of a guitar noob?  I did the 18v mod a few weeks ago and haven't really had the chance to play that much but it seemed better through my pedals than worse. Now I'm gonna have to go play around with it.
Title: Re: Tailoring circuits to suit active pickups
Post by: DougH on August 25, 2010, 10:30:56 AM
In general a lower impedance input on an effect should work better. For example, instead of the usual 1M shunt to ground, try something lower, maybe 22k or something. You will have to experiment.

If the effect depends on loading a passive pickup for its sound, like a fuzz face or rangemaster, you will need something that emulates a passive pickup on the input. Check Jack Orman's site for his "pickup simulator" which involves using an inductor and a couple resistors and caps.
Title: Re: Tailoring circuits to suit active pickups
Post by: Paul Marossy on August 25, 2010, 10:31:55 AM
Quote from: ghostsauce on August 25, 2010, 10:25:58 AM
Anyways, about the 18v into your pedals.. Uh... I've never noticed a difference. Am I that much of a guitar noob?

Those active EMG pickups are not putting 18V into your guitar pickups. Instead of maybe a 100mV PTP output like a regular passive pickup, it might be say 250-300mV PTP going into your guitar pedals. That's not going to be that much if a huge, dramatic difference. They just operate on 18V for the higher headroom, that's all.
Title: Re: Tailoring circuits to suit active pickups
Post by: Galego on August 25, 2010, 11:01:01 AM
As said (i think) EMG's at 18V aren't any louder than EMG's at 9v or lower at 27v. Just like a pedal doesn't get twice as loud or twice the gain if you run it above 9v.
Title: Re: Tailoring circuits to suit active pickups
Post by: ghostsauce on August 25, 2010, 11:15:14 AM
Gotcha. Yeah all I noticed was the added headroom, and it does sound a little warmer to my ears. I was really happy with the mod, being simple and is worth the battery snap & drain. After playing it for a little while just now I realized it wasn't bottlenecking after all.
Title: Re: Tailoring circuits to suit active pickups
Post by: will queue for free stuff on August 25, 2010, 05:26:47 PM
DougH said
Quote from: DougH on August 25, 2010, 10:30:56 AM
In general a lower impedance input on an effect should work better. For example, instead of the usual 1M shunt to ground, try something lower, maybe 22k or something. You will have to experiment.

If the effect depends on loading a passive pickup for its sound, like a fuzz face or rangemaster, you will need something that emulates a passive pickup on the input. Check Jack Orman's site for his "pickup simulator" which involves using an inductor and a couple resistors and caps.


Thanks for taking the time to post. That's a great suggestion, I'll check out AMZ.
Title: Re: Tailoring circuits to suit active pickups
Post by: will queue for free stuff on August 25, 2010, 05:59:45 PM
Just thought I'd post a link to Jack Orman's site, I think it's exactly what's needed.
Thanks again DougH.
http://www.muzique.com/lab/pickups.htm