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Output Impedance Of Variax- Matching To Amps


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#1 markhughes2000

markhughes2000

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Posted 25 March 2014 - 05:57 AM

Please forgive me for the length of this but I am trying to put a s much detail into my problem as poss

 

 I have a Variax 500 with EMG passive mag pickups fitted.

 

I have had this problem for a while but have recently fitted a set of Graphtec saddles to and I think they have made a slight improvement to general variax tone. My initial thoughts were it was much better on acoustic and 12 strings but I have got used to the sound now so it is difficult to be subjective.

 

Background info

 

  • I have set the string volume level in line with the mag pickup volumes.
  • This was done using the line 6 spider jam amp
  • I turned the output level for spank2 up to match the lester bridge and it did not seem to alter the quack sound as long as the individual mix of the pickups were set right.
  • Ive read that the Variax is a low impedance and classed as an active device.( O/P Z from TL082 is very low  though a 475 ohm resitor
  • I understand  Pick ups Z  range from 6k to 15K

 

If I connect the guitar via the ¼ inch jack I get different  results depending on which amp/effects it is connected to.

 

I am comparing the spank2 position of my mags ( which is not especially quacky by the way) which I assume is about 3-4k ohms (a shorted pole on humbucker in parallel with the middle pick up) -with the Variax spank position2

 

I am confused about the inconstancies in tone depending on which load is presented to the guitar

 

  1. Connect direct in to a Dynacord  powermate line in jack  impedance  >10kohms
  • Variax levels are louder than mag pickups –
  • mag pickups sound flat as they are passive ( as expected need to boost treble and gain for good sound)
  • Variax sounds bright on all models almost as if they are preamped
  • spank 2 sounds like the real thing much better than mag
  1. Connect into Laney Valve amp Hi sens input
    •  Vax spank2 quack is better than my mag version but Vax volume is the same as mags now!
  1. Connect to Line 6 spiderjam amp  guitar input or Aux input
    • Volume levels are the same but variax tone (spank2 quack is lesst)
    • Mags don’t sound as pure
    • Actually clean sound is muddy ( think this is just the amp sound)
  1. Connect to Boss GT3 effects pedal I/P Z 1Mohm o/p through the PA
    • Mags sound great on my favourite clean patch ‘Teletwang’ spank2 -nice and “bottally”but when switch to variax spank2 it doesn’t sound as bright as if it were limiting. It sounds less crisp and sounds exactly like the mags with the vol pot down 25% -
  1. Connect to Line6 XT live via VDI- I/P Z N/A
  • Variax Sounds bright and tone not attenuated (as expected)– sounds better through PA with o/p in direct mode
  • Cant get a decent clean tone out of the mags –and noisy if both inputs are used anyway
  • After many hours of playing around sounds go to heap of junk when using a guitar amp even with o/p selector changed  -need to go back to Boss pedal
  1. Connect Guitar through Line 6 XTLive jack input input Z 1 Mohm
    • Cant find a patch were Mags sound as clean is as Boss pedal
    • Switch to Variax spank2 is not as good as mags spank2

So I am frustrated that when using the valve amp/ PA  and the VDI  I can really appreciate the pure variax tones but they appear to be supressed when going into the input jacks of both my effects boxes! and then on to an amp. This limits my use of the Variax sounds live and nearly always revert to the mags unless I want a special low noise overdrive or special tuning acoustic sound ( which is better DI through PA)

 

I have a couple of theories to why this may be happening but would welcome your input or any body elses thoughts whos had similar problems getting a nice clean sound for the vax

  • Variax string volume is maybe still too high as indicated when plugged into mixer amp and this is overloading effects pedals. If I turn it to lower than the mags will it solve problem?
  • Variax jack output presents a much lower impedance ( <500ohms) than the magnetic pickups and if it is put into a high 1Mohm input the mismatch is more noticeable than a 10K mixer i/p.
  • The guitar effects box inputs are normally expecting a passive pick up input from a magnetic coil and so provide preamp and boost whereas the Vax active o/p from an Op amp is somehow  being limited or mismatched by this input circuit
  • Will changing the order of the effects  present the guitar with a different load. i.e instead of compressor first  put eq Ive noticed it is not so dominant on other patches
  • The Mag sound I have through the BOSS teletwang patch using spank 2 is unique (not quite true spank2) and so I would perhaps need to taylor another patch to emulate it with the vax strat model but saying that if I put my strat copy through the patch it sounds brighter and more bottlier still!than any of them
  • Whats  going on Line6?

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