VOX AC30-6 Normal / Bass / Treble (non top boost versions)

Discussion in 'Amp Central Station' started by HF1600ie, Sep 21, 2021.

  1. HF1600ie

    HF1600ie Tele-Meister

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    Hi,
    As we all know, these JMI era "non top boost models" are usually featured in the recent AC30 versions which incorporate them in a channel which they more recently call the "normal" channel.

    But we all know that there were 3 versions of non top boost models (After 1960) - the AC30N (Normal), the AC30B (Bass) and the AC30T (Treble). Generally speaking, they all shared almost everything in the circuit, same structure, and only had different capacitors (or resistors) in specific places of the preamp, everything else equal. Those changes defined each of the versions "tone".

    But also, and for more variety in tone, each of this Bass/Normal/Treble versions had two inputs to choose - the "normal" and the "brilliant" input. If I´m not wrong, this last one later on received the extra gain stage (the brilliance unit) to create what we know as the "Top Boost" channel.


    In the recent versions, VOX seems to have chosen the AC30 Normal version in its "normal input" to be the flagship of the "non top boost" models. They didn´t pick any of the other configurations for this purpose.
    But, instead of PI coupling caps of 47nF/150nF, they went 100nF all-around at the PI.
    They still use a 47nF V1 cap, but for added flexbility, Vox recently added a 220pF bright capacitor in the volume pot (either wich a 330K resistor or not) or variants on this which is an idea from the AC30 Treble (330K/220pF).

    So, my question is :

    How close is this to the AC30N brilliant channel which didn´t have any bright cap in the volume pot? I mean, having a 500pF coupling capacitor in V1 without a bright cap "versus" the 47nF plus a 220pF bright capacitor in the volume pot will make them close in tone? It seems like VOX wanted to find a way to get a warm and spikey tone at the same time...instead of doing it the old way with the brilliant channel of the AC30N. So, how accurate are VOX recent choices on this to represent the old non top boost tones?

    - Which, from all 6 options (Bass/normal/Treble plus Normal or brilliant input from each) represents better the Vox AC30 tone from that 60s era ? I speak of Beatles, Shadows, Surf music, etc. Which configuration would you choose ?
    I seem to hear bright AC30 here and there but also warm/darker AC30 tones... which also seem to fit well in the mix and have their place too.


    Thanks !!!
     
    Last edited: Sep 21, 2021
  2. milocj

    milocj Friend of Leo's Ad Free Member

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    I have a 1962 that still has it's original cone Blues. I'm pretty sure mine is a normal version and for me the normal channel on the high input is my favorite spot. The brilliant seems to lose too much bass/mids.

    I actually like the vibrato channel quite a bit, too, but the volume needs to be run quite a bit higher to match the volume of the normal.

    I've built up a too-boost module for the amp and just haven't felt the need enough to actually wire it in.
     
  3. HF1600ie

    HF1600ie Tele-Meister

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    OK, good input ! That´s the relatively "darker" AC30N tone I am talking about. The AC30N in its normal channel (high input) is one of the references.

    I don´t seem to see that much appraisal over the AC30Bass and AC30Treble versions. Eventually, the AC30Bass in its Brilliant input could be interesting. I´ve head complaints over the AC30 Treble being just too excessively bright.

    The Brilliance module which is applied in the middle of the AC30N Brilliant channel path may have been created due to limitations on the Brilliant channel alone ? Maybe lack of warmth and compression?

    I wonder if the AC30N Brilliant channel (alone) gets the appreciation of others and how wide was its application in the 60s ?
     
    Last edited: Sep 22, 2021
  4. HF1600ie

    HF1600ie Tele-Meister

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    Hi, any other inputs?
    I´m trying to "voice" my AC30CCH (head) properly in the normal channel (my favourite) and suggestions are more than welcome.
    Thanks
     
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