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Do tube DIs buffer (colour) the unbalanced output?

Discussion in 'Amps, Mics & Pickups [DB]' started by jar240, May 27, 2005.


  1. jar240

    jar240 Supporting Member

    Hey folks, do all the decent tube DIs (Avalon, Demeter, etc.) buffer the 1/4" unbalanced output, or are the INs and OUTs merely connected in parallel?

    I was surprised I couldn't find blocks diagram for the Demeter and Avalon products on their repective websites.

    Thanks,
    Chris
     
  2. I can't speak from experience with Avalon or Demeter (I wish!) but in all DI's I've dealt with the 1/4" output is just a parallel connection off the input - it's signal doesn't go through any of the electronics. Otherwise musicians wouldn't consent to it being put in their signal-chain.
     
  3. PB+J

    PB+J

    Mar 9, 2000
    arlington va
    The Avalon U5 is not a tube DI, it's all solid state

    I'm not sure I understand your question--is it possible to buffer a 1/4 inch output? I thought it was only possible if the 1/4 inch was a TRS jack. I thought you needed three contact points for a buffered output, but I may be wrong

    I can't hear any coloration when I use the 1/4 out to drive a power amp--or rather , I can't hear any difference in sound between the 1/4 and the line out
     
  4. jar240

    jar240 Supporting Member

    I sit corrected! ;-)

    Every effect pedal that doesn't incorporate true, mechanically-latched, bypass switching (about 90% of them out there) have buffered input, and they're unbalanced. In those cases, colouring the sound is bad (i.e. buffering is referred to as tone suck). With a tube DI, I'd want the colouring, since it's typically the addition of harmonic content.

    I've found this tube DI review that's just stellar, and answers my question exactly:

    http://emusician.com/tutorials/emusic_direct_action/

    In summary, 7 out of the 8 tube DIs tested buffer the input; only 1 out of the 8 tested had it's unbalanced output wired in parallel with the input.

    I was bothered to see on one of the BBE non-tube DIs, that you dial the effect in only for the XLR balanced out, while the unbalanced output (to your amp) remains unchanged. Who would want that? They should at least put a switch on there to have the option! ;-)

    I think I'm going to find me a Demeter tube pre...

    Thanks,
    Chris
     
  5. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    Thanks for providing the link to that article, Chris! Unfortunately, it doesn't make my current decision - Aguilar or Demeter - any easier! Do I prefer the minimalist "audiophile" signal path of the Aggie, or the added gain stage (and hence, added flexibility) of the Dem?

    Decisions, decisions...

    Tom.
     
  6. jar240

    jar240 Supporting Member

    Just get both: Bass -> Aguilar -> Demeter, and voila, best of both worlds! It lets you colour both inside and outside the lines! ;)

    I'm playing more live shows than doing studio work, so I'd prefer the Demeter. Let me ask you Tom... I play both upright and electric basses, and use effects at several gigs. I'd be using the Demeter as a tube colour stage at the beginning of the chain, but because I'm using effects, I'd still have to use the actual DI out in my iAMP 800C, or only the uneffected sound will be sent FOH. I have a true bypass loop switcher that switches all the effects out of the circuit so only the clean tone gets through when the effects are off.

    Are there any tube pres in the ~$500 price range and Demeter DI size that give me a TRUE tube stage (i.e., none of the disgusting transistor peaking) and allow me to overdrive the input a little?

    Thanks,
    Chris
     
  7. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    I'm still learning this myself, but Max Valentino might be the man to talk to.

    Tom.
     
  8. PB+J

    PB+J

    Mar 9, 2000
    arlington va
    Nothing at all against any of the other units, which i'm sure are excellent, but it's hard to go wrong with the avalon--it does everything the demeter does, for example, but the tone presets are extremely effective and give you the flexibility to use it as a preamp. It can drive the PA and a power amp at the same time. it has two balanced xlr outs and one 1/4 inch unbalanced out. I was a tube purist till I tried the avalon--there's nothing "solid state sounding" about the tone

    the downside of the avalon compared to the demeter and the aggie is, it seems to me, that the avalon is bigger and the input impedance is three meg ohms instead of 20 and 12. Not sure it makes a big difference