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Audere Pre - Blend seems wierd

Discussion in 'Pickups & Electronics [BG]' started by joelb79, Jul 17, 2007.


  1. joelb79

    joelb79

    Mar 22, 2006
    Lansing, Michigan
    I have had two audere preamps in the last 1/2 year and I've noticed something about them when doing some wiring modification. My center dent is quieter with both pickups connected than I would expect.

    When I blend to the neck or bridge solo, the output is WAY louder, enough of a change to cause a hard clip if I'm riding the light blended 50/50. Passive electronics make a phase cancel volume change when blending between pickups, but always seem to make the treble and bass louder. The audere seems to go quieter when blended in the middle regardless.

    I wanted to do some experimenting with the preamp to see what makes it work like that and i've discovered something very interesting, when you unhook the bridge pickup and blend to the neck 100%, blending backwards causes a volume drop on the neck. Meaning, output drops when going to the center regardless of what else is going on.

    On a normal blend pot, you do not have a signal drop when blending to the middle position. On the audere, it seems to taper anywhere from 6-10db going from the neck to the center dent. I am not sure if this was by design to balance the pickups.

    To further experiment, I decided to wire both the neck and bridge to the neck input and see if the bass sounded better. I should record a reference track and use the waveform to make a better determination on this, but I can notice a HUGE difference in both pickups connected to the neck from both pickups run individually.

    I'm now not sure I agree with audere's active blend circuit anymore. I think the traditional way of using 250k pots and feeding a passive blend into an active pre works better.

    I asked Dave about this pre-sale because i noticed it with an older audere and dave answered with this:

    I would be interested in the mod. I love these preamps because they are modifiable, but to limit the volume when blended in the middle is limiting to my tone.

    Both pickups connected to the neck input sounds GREAT. Both pickups connected normally blended center sounds quiet and different.

    Interesting isn't it?
     
  2. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    Interesting cause I had someone ask me to run a similar check on the findings of a blend not that long ago. Given I’m a trial and error guy, I can do that and describe the result. If they want some theoretical explanation for the results they’ll have to go to someone like David.

    I’m not sure if I’m understanding exactly what you did and what you’re results were but maybe you’ll understand mine (I definitely am not clear on the part about both pups connected in one place other than like basically wiring both pups together functioning as one to where there’s no separation, so you’re not blending anything).

    Per request, I simply removed the bridge pup out from under the strings so it didn’t read them, did a pan from the lone pickup to both pickups, and the load of the extra pickup effected the sound proportionate to the mix in the blend. In addition:

    Easier to discern than describe but was clear that tone becomes gradually less defined to blatantly dull sounding at the detent relative to the full 100/0 setting. It struck me that there seemed to be a progressive lowering of volume from 100/0 to the detent as well but that was uncertain. Anything to me that is questionable I throw out. Either it exists or it doesn't. There are too many things that jack with your ears (primarily your head) to give the benefit of the doubt in the other direction.

    I wish I'd paid more attention to the down side when the read pup would be mixing in with the non-read pup but I only ran it down a couple times cause that wasn't my focus as I didn't percieve that to be part of your question. The volume obviously tapered to nothing but In recall the tone seemed very dull throughout and overall volume significantly lower than I'd expect.


    This was a passive setup but I’ve noticed the same kind of thing with preamps. I don’t use onboard controls any more and when I did I favored two volumes but I don’t remember that kind weirdness with them, but I don’t have much faith in my memory.

    It’s interesting David said “most” preamps but that jives with my experience cuase it's been all of them - but I’ve never had an active blend either. I thought the whole point of one was to resolve that issue. I think that’s what the EMG’s all about but I’ve only had the controls not the systems cause I don’t want to be stuck using EMGs - or actives (whatever it actually is - they say EMGs only but I haven’t had one to find out) with any pre.
     
  3. joelb79

    joelb79

    Mar 22, 2006
    Lansing, Michigan
    I never noticed it when my bass was vol vol tone. There was a distinct difference. Not a volume drop but a phase issue that any two pickup bass is going to have. Thats why you sound more scoped when you blend both together. The mids from the neck are out of phase with the bridge.

    When I have both pickups connected to the neck input of the audere and blend from center to neck, the volume increases. It seems to me that the only time the volume should drop on the neck is when blended towards the bridge.
     
  4. Jeff Moote

    Jeff Moote Supporting Member

    Oct 11, 2001
    Beamsville, ON, Canada
    No, this is incorrect. See the image below: the first plot is what you're describing with each pickup volume dropping off only on the opposite half of the blend. What the Audere does is doing is shown in the second plot. The third (excuse my crappy curves) is how a traditional passive blend works, showing why only about 10% of the rotation on either side of half actually works.. the rest is basically 95% one pickup or the other.

    All plots are normalized to the fact that audio is actually a log function (i.e. they show what you hear, not the actual signal). This also explains the phenomenon with the passive pickups since linear pots are often used for blends and you end up with a linear plot (like the second one) before normalizing to log scale, so what you hear is the 3rd plot.

    Blendpots.

    For what it's worth, I didn't experience the volume drop with the 3ZB so perhaps you have some issues with yours and/or the way it works with the pickups.
     
  5. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    I used to think I preferred two volumes to a blend because the blend didn't seem very intuitive to me, in the sense that it didn't really seem to make sense the way it worked. In fact I thought it graduated from 100%-0% going in each direction (like the above drawings imply). So I thought at the detent it was just a 50/50 mix of each pup - cause that's what it sounded like from rotatig it. Either that or as Joel mention they seemed to jump in output as soon as you moved off the detent. On the other hand the response you get from controlling two seperate volume pots is pretty obvious.

    I'm guessing that if I sent up another experiment where I could A/B two volumes and a blend, the blend would sound comparatively dull in tone and lacking output. From the experiment and JM's post, what I was attributing to inuitive control was more likely a quality of sound issue.
     
  6. joelb79

    joelb79

    Mar 22, 2006
    Lansing, Michigan
    I can tell you this after much experimentation:

    If both pickups are connected to either the neck or bridge input together, the sound is louder when blended towards the neck or bridge (respectively). The volume goes down SIGNIFICANTLY when blended center.

    If both pickups are connected to their respective inputs, the volume is quieter when blended center.

    Hence my reason for thinking that something funny is going on with the blend. You synopsis is right on what the pot actually does, its a nice linear transition in volume, however I find that its quieter for both pickups with in the center than it is when blended in either direction.

    I'm going to rewire my bass, Vol-Vol-Tone-Bass/Treb using an OBP-1 and dual 9v batteries. I'm not jiving with the Audere anymore. The Z-modes are not useful for me, I just use the Mid-Z. I'd much prefer a passive bass if possible as well, so I will incorporate a SPDT switch on the tone pot for a preamp bypass.

    I might just bite the bullet and get a sadowsky pre, but i'm undecided at this time. The difference is around 75$.
     
  7. The Penguin

    The Penguin duplicate account violation Banned

    Jun 21, 2006
    I'm not pelagic
    Can you give an example of who does this? Every blend pot I've ever checked with a meter (which is a bunch) has ranged from minimum to maximum resistance in just half the sweep.
     
  8. The Penguin

    The Penguin duplicate account violation Banned

    Jun 21, 2006
    I'm not pelagic
    That does sound like it's wired like Jeff's second drawing. If you look at the Audere site he kinda admits to doing this
    http://www.audereaudio.com/FAQ_ActiveMixing.htm
    and since the preamp only has a dual pot for blend and mid this seems likely. I don't consider that an acceptable way to blend pickups. Bartolini's active blend is both full on at center detent as is every other one I can think of.
     
  9. joelb79

    joelb79

    Mar 22, 2006
    Lansing, Michigan
    And he goes into saying that you can do a 100% balance by modifying the 3ZB. I think that is what I'm effectively doing by wiring both the neck and bridge to one input. Let me tell you, it REALLY opens up the sound of the bass.

    Unfortunately for me, this still means I'm going to an Aguilar OBP-1 for a more passive sounding bass with eq options.
     
  10. ibz

    ibz

    Apr 14, 2005
    Columbus, OH
    Wait how exactly does the blend pot's function change when you wire it this way?
     
  11. Aarix

    Aarix

    May 19, 2006
    Raleigh, NC
    I do notice a teeny volume dip. I don't think it's 6db though... It's mostly noticeable on mine going from center to neck, probably because that pickup is a little too high. I've never noticed it before.

    I get a similar, but slightly less noticable effect from the Bartolini NTMB in my Lakland.

    If you had both pickups 100% at the center, you'd expect a volume bump summing them together (3db I think).

    Personally I think it's a small price to pay compared to dealing with passive blends or vol/vol configs which in my experience amount to little more than on-off switches. There's a whole spectrum of usable tones in the Audere. I don't find myself panning from center all the way to either side with a buffered pre anyway.
     
  12. The Penguin

    The Penguin duplicate account violation Banned

    Jun 21, 2006
    I'm not pelagic
    There's a drop in volume when 2 pickups are at 100% since they are wired in parallel, in series you would get more volume. This is why the Bart in your Lakland has a small drop. Using the wrong kind of blend just makes it worse.
     
  13. Audere

    Audere Supporting Member Commercial User

    Apr 7, 2005
    South Beach, OR
    Owner: Audere Audio
    The center is slightly lower in volume - less than 2 dB of voltage - flat with frequency.

    If you are getting a big drop like 10 dB then you probably are having a phasing issue with the pickups.
    In theory, out of phase they would drop completely out.
    In practice, the 2 pickups are sensing different things from the strings.

    FWIW I have seen single coil pickups where out of phase they had around 10 dB of noise reduction.

    So invert the 2 leads on only 1 of the pickups. It will either be better or worse and I think you will notice.

    Some pickups have different magnetic field sensing shapes and therefore different cancellation in the center.

    The phase response though the preamp is equal for both inputs and you can get cancellation of signals out of phase.
     
  14. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    So 2 dB shouldn't even be noticeable correct? Unless the dullness of tone that typically appears at the detent also makes it seem more dramatic than it actually is, higher frequencies dropping out/whatever.

    "flat with frequency" I assume means with controls set no boost/no cut. If so, how that's that 2 dB figure change with boost/cut in bands thrown into the mix?
     
  15. Audere

    Audere Supporting Member Commercial User

    Apr 7, 2005
    South Beach, OR
    Owner: Audere Audio
    By flat with frequency - all the audio frequencies are changed by the same level as the balance control is moved.

    It would have been easy to create a system where the center would be X down at low frequencies and the reduction would have increased to Y down at higher frequencies. In reality this will always happen for some technical reasons but in our case it is an insignificant change (i.e. less than 0.1 dB)

    Assuming in phase input signals:
    Tone controls variations have no effect at all.
    Z-Mode variations also have no effect.

    But if his reduction is due to cancellation of out of phase input signals then Tone controls and Z-Mode variations could be significant from a user’s prospective.
     
  16. joelb79

    joelb79

    Mar 22, 2006
    Lansing, Michigan
    Phase was not reversed.

    FWIW - I hooked the pickups up right and the change was not as abrupt as I was describing it. It is more along the lines of 2DbV.

    Dave - Does the vol-vol models function like this, meaning both on is -2BdV? Or would I just be dealing with the natural phase cancellation sound of the two J pickups?
     
  17. Audere

    Audere Supporting Member Commercial User

    Apr 7, 2005
    South Beach, OR
    Owner: Audere Audio
    On the Vol, Vol setup the level in the center (i.e. both vols maxed) increases to +1.7 dBV - flat with frequency... when compared to either PU maxed and the other PU at 0.
     
  18. The Penguin

    The Penguin duplicate account violation Banned

    Jun 21, 2006
    I'm not pelagic
    How do you get a boost when other pickups show a cut when both are on full in parallel?
     
  19. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    So let me see if I'm getting this. At the detent with a blend you get a -2dB drop but with V/V you get +1.7dB with both volumes maxed?

    Which translates in getting roughly the same increase in "volume" using V/V as loss in using a blend at the detent?
     
  20. joelb79

    joelb79

    Mar 22, 2006
    Lansing, Michigan
    Yeah, the problem for me was that center was 2db quieter than blending to any pickup, and for me the volume difference meant changing more than just my balance to make neck or bridge blends work. I would say once I get 1/2 the way towards either bridge or neck, i need to make a volume/eq change, which was not the case when running a passive bass.

    My solution in this is to go with a vol-vol Audere hopefully. This means loosing 3-band EQ to keep the tone control, but i'm finding the mid is not as useful for my playing style with a Jazz bass.
     

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