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pickup hieght

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Chambers, Jan 31, 2003.

  1. Chambers

    Chambers Guest

    can someone tell me why , when you install a pickup, does it ahve to be raised a certain height from he strings? because of frequency? or tone or what? also, can someone tell me the difference between analog and digital pedals? pros, cons...it woudl be a big help, thanks
     
  2. decay-o-caster

    decay-o-caster Member

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    A couple of quick and dirty answers before the knowledgeable folks chime in -

    You adjust the pickup height to get the best tone and to help balance the output of the other pickups and the relative output of the bass vs. treble strings (the bass strings output more, usually). Closer to the strings, generally, the stronger/louder the output. Farther from the strings = quieter. So since your bridge pickup tends to see less string vibration (because it's next to the bridge, the strings move smaller distances due to the geometry of the whole mess), you might have it closer to the strings, while your neck pickup would want to be farther away so when you switch pickups, the neck pickup volume doesn't jump too loud.

    But too close to the strings, the pickup magnets can actually dampen the strings and drag them out of tune. So you can't just raise 'em till the strings just barely clear. Evidently, this is a big problem on Strats.

    A digital pedal "translates" your analog signal into a bunch of 1s and 0s and processes them, then "translates" the processed 1s and 0s back to wave forms. This can (but doesn't necessarily) sound kind of dry and clinical, not the sort of messy, warm sound you get from messing with wave forms in the first place.

    Now Unquiet will give you the real answers! ;)
     
  3. Chambers

    Chambers Guest

    alright, thanks alot man, that was really helpful
     
  4. LSchefman

    LSchefman Member

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    I'll add a little to DOC's post.

    I don't know squat about pickup heights, I usually leave em where the factory sets em (hey, what do I know, they sound good there to me).

    Digital gear has a few essential problems to overcome. The signal from your guitar is analog. So the digital gear must use Analog-to-Digital (A/D) converters to make the signal into the ones and zeros. You are starting with an analog stage, and converting to those ones and zeros, but the ones and zeros must be "approximated" because ones and zeros create "steps" or quantization.

    Instead of a smooth sine waveform, for example, in the digital world it's a staircase, with little zigzags.

    The higher the bit rate, the closer to a wave it appears to be, and the higher the sample rate, the better the frequency response on the high end, but remember it's still an approximation.

    Then we take this approximated waveform, and convert it into the analog world again so your amp can play it back. A Digtal-to-Analog (D/A) converter does this chore.

    So your signal has to contend with not only the quality of the analog circuitry, it also must contend with the conversion and the digital algorithms that change the sound. In something inexpensive like a pedal, the circuitry may not be all that great, and there is another issue: All digital gear has "clocking" issues. The better the clock, the better the digital stuff can handle the approximation and reconstruction of the signal. If the clocking isn't accurate, or "jitters", the signal is further compromised.

    That's why a lot of digital stuff does indeed sound sterile. It's dealing with a whole lot of things that analog stuff doesn't have to contend with.

    Still, I prefer digital for time based things like delays. The algorithms can be more powerful in the digital world, and when they are, you can have incredible stuff happening.

    IMHO, digital gear is a lot less successful when it tries to accomplish distortion stuff.

    I hope this helps a little. I also hope I'm not leaving anything important out. But if I am, Unquiet will soon be along to straighten me out. ;)
     
  5. Chambers

    Chambers Guest

    thanks alot , that explains alot of things, but another question, what companies make anolog pedals? and which analog to digital pedals would u consider dealing with heavy metal?
     
  6. John Phillips

    John Phillips Member

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    The pickup height thing is easy - as DOC said, closer = louder (and usually fatter-sounding). Too close and - especially a with single-coil, direct-magnet (ie the "polepiece" is itself the magnet), neck-position pickup, you can create a 'false node' in the string, which can actually make it sound out of tune. Strat neck pickups are the biggest offenders.

    Digital vs. analog. Analog is cool, digital is not. :p OK, maybe it isn't that simple...

    Les said most of it. Digital processing can do very powerful things that analog can't, more cleanly and with less background noise. But it can sound too clean and characterless sometimes.

    There's another thing - in a lot of digital effects, the direct portion of the signal (eg the un-delayed note in a delay pedal) remains analog; only the 'effect' portion is digital. Most simple digital delays, and delay-based effects (chorus, flanging etc) are like this. They sound very different (to me) from the ones where everything goes through the digital processing - all digital-modeling effects are like this AFAIK, and IMO sound bad. Somehow the digital nature of the direct signal kills the natural warmth and 'tone'. I find the difference most noticeable if the 'digitization' occurs before any tone-shaping or especially overdrive stages; less bad if used at the recording and mixing stage - and I prefer digital to analog these days for the actual recording process (but I don't have access to really high-end analog).
     
  7. PerryR

    PerryR Supporting Member

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    Hey Les, your entire post on AD/DA should be in a FAQ! Very easy to understand, good analogy's and spot on info.
     
  8. PerryR

    PerryR Supporting Member

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    Hey John,

    I wish all digital pedal effects were like that. At least any with a mix control, delays, verbs, chorus etc... I really have never seen a digital effect (in a pedal) that didn't digitize the whole signal. I think many of the digital delays and verbs could be substantially better if they maintained an anolog dry signal and used an anolog mix stage. The Line 6 DL4 would be a stellar effect to employ that idea.
     
  9. John Phillips

    John Phillips Member

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    Perry, I'm reasonably sure the Ibanez Echomachine (digital delay emulating an analog) does not digitize the direct signal. I'm basing this on my ears (if you set the 'echo level' to zero, I can't hear any difference whether the pedal is on or off) and more tellingly that if you look at the latency - I recorded the pedal output in parallel with a dry signal that didn't go through it - there is none. This would indicate that the direct signal does remain analog; the Line6, which started me on this whole investigation, to find out why it screwed up the sound, has clear latency even when the pedal is switched off (in non-true-bypass mode), and on the direct notes when it is on.

    On the basis of the Ibanez, I would expect most simple delays (I must borrow some to test...), eg the Boss DD3, probably do not digitize the direct signal; there is actually no point, it would complicate the circuitry more than necessary since there is no control over the direct sound at all, not even a mix control (unlike on the Line6) - only a level for the delayed sound.
     
  10. PerryR

    PerryR Supporting Member

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    Hey John,

    Well right on! That must explain why the Ibanez echo machine sounds good....to my ears anyway. I wonder about the Holy Grail, or Digitech Digiverb. Thanx for the info, and I would be very inetersted in your findings on any other pedals that you discover a lack of Latency problems.

    The DL4 is such a great effect, I am really surprised they didn't opt for and anolog dry signal. I mean they went the extra mile for true bypass.....doesn't make a whole lot of sense.

    I thought just the opposite, I figured that keeping the whole signal digital was an easier design, omitting the anolog mix stage.

    Good info John, thanx!
     
  11. JPF

    JPF Member

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    You guys are amazing. Really. Even my 13-year old son understands now why his digital OD pedal sounds "buzzy". Now he won't settle for less than running through my Austone. Thanks, guys;)

    One dumb question of my own:

    Do active pickups (EMG SAs, in this particular case) convert the analogue to digital and back again? What's the trick behind their being so quiet?

    Please help, I need to stay 1 step ahead of my sons in these matters:)
     
  12. John Phillips

    John Phillips Member

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    They're purely analog. They are low impedance (winding picks up less interference), low magnetic-strength (which means they can be set very close to the strings without affecting them), hum-cancelling pickups - even though they look like single coils. The low windings and magnet stength would normally make them very low output, but they also contain an active preamp which not only amplifies the signal to 'normal' passive pickup levels or above, but buffers it and makes it pretty much immune to the loading too.

    This is a really good system - it sounds like it cures all known guitar pickup problems at one go (including removing the need to ground the strings, which is a shock hazard), but the actual tone is just a little too modern and hi-tech for some players (including me) - I prefer slightly more warmth and 'rawness'.
     
  13. JPF

    JPF Member

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    Thanks, John. I agree with you that they lack warmth. They're good for recording, as they're extremely quiet, but lack that warmth, especially when run through my Koch Multitone, which is pretty "modern" sounding to begin with.

    I suppose I have good reason to add another Stratocaster to my harem...
     
  14. Chambers

    Chambers Guest

    JPF, that was a really good question, I have emg's of my own and I've always wondered that exactly question, but i never remembered to ask it, thanks alot.
     
  15. JohnnyL

    JohnnyL Member

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    I have used it for many years and have tested it at zero settings. There is no change in the sound of the guitar whether on or off. I would prefer to own an anolog delay but I don't. However, the DD3 does a good job IMO.

    Peace,
    J
     
  16. PerryR

    PerryR Supporting Member

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    Hey John,

    Can you elaborate a little on how you look for latency. I see you record the source in parallel with the effect (mix low to test the dry portion), and then do you listen for phase cancelation or is there some type of software.....I've nevr tried this and I would like to.

    Thanx!
     
  17. John Phillips

    John Phillips Member

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    I recorded the two paths into my computer as a stereo track, then looked at the waveform analyser in Cubase. At maximum resolution, not only can you see the latency, you can measure it from the timescale.

    Neither the Boss DM2 or the Ibanez Echomachine has any detectable latency on the un-delayed notes (even analog can introduce phase shifts, so I thought I'd check the DM2 as a 'control'). I'm hopefully going to be borrowing a DD3 and a DD5 this weekend to try.

    The Line6 DL4 has about 1.5mS - which doesn't sound a lot, but it completely screws up the sound if you mix the unit in parallel with the dry signal, unless it is set to 100% effect - not always what you want, since then you have to adjust the FX mix on the amp to control the effect level for different patches, and you can't use the loop sampler (since its maximum mix setting still has the full dry signal). The result is a horrible thin, comb-filtered sound. Guess what - I don't own the DL4 any more... this was one of the major factors.
     
  18. PerryR

    PerryR Supporting Member

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    Hey John,

    Much appreciated. That seems like a simple process.

    I have a stereo digital recorder. Split the signal with my whirlwind buffered splitter, one split (A) goes straight to the input pre of channel A, The other split (B) goes through the device under test and then to input pre of channel B.

    Now, I guess you would not use a sine wave as the source, but instead actually play guitar for the source. Do you use more single note stuff or chords or does it seem to even matter?

    Thanx
     
  19. John Phillips

    John Phillips Member

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    It shouldn't matter what you play. For simple latency tests all you need is a note; I just muted the strings, hit record, then played a single note. The transient at the start of the note is quite steep and obvious. If you then place the marker line over them you can see if they are exactly coincident or not - but you do need a fairly big horizontal resolution to see it.
     

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