Vox AC15C1: Bright cap mod, yes or no?

Discussion in 'Amps and Cabs' started by Zacateca, Apr 9, 2015.

  1. Zacateca

    Zacateca Member

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    I have been debating this since I got the amp about a year ago. Since it does have a tone cut that works really well IMHO, is it really necessary to do the bright cap mod for it to take pedals? I am afraid that if I do I will lose the amps true character, and of course I donĀ“t want this to happen.
     
  2. plexirocker 68

    plexirocker 68 Member

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    Do it, it's a vast improvement
     
  3. sa1126

    sa1126 Member

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    I thought the amp sounded fantastic without it so I never did it to mine. YMMV. What issue are you having with the amp taking pedals?
     
  4. hacinador

    hacinador Member

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    I really hate Vox amps without a bright cap. An amp is dull sounding with its character lost. But its me, one can love it without a bright cap!

    You can try several values of bright cap that can be more pleasant for your ears. 50, 68, 82 or 100 pF can work better, it depends on your guitar, playing style, guitar cable, pick etc. It is very cheap mod, few values for trying cost about the same price as a set of strings...
     
  5. metropolis_4

    metropolis_4 Member

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    The question is - what problem are you trying to solve?

    I would say, if you're not sure it's really necessary, then it probably isn't.
     
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  6. Zacateca

    Zacateca Member

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    I am now using the normal channel exclusively and there is really no problem there. I want to be able to use the top boost channel. There is a considerable ammount of fizz whenever I put my distortion pedals in front, but it tends to diminish with the tone cut. I have not used it in a band context yet, so I don't know how it is going to respond at gig volumes. I read that at such volumes the bright cap gets bypassed but I did not have the chance to try it.
     
  7. DrainBamage

    DrainBamage Member

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    This might not help you as I haven't used pedals in 10 years but distortion pedals usuly sound better in a clean preamp like the normal channel.
     
  8. Trevorsnackson

    Trevorsnackson Member

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    Agreed. I use the normal channel and feel no need to do bright cap. Its takes pedals much better than the Top Boost channel IMHO. I haven't put a drive into it that didn't work.
     
  9. geek-mo

    geek-mo Supporting Member

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    Also good to note that the bright cap is primarily for lower volume playing. Turn that amp up and you won't notice the difference if if the bright cap is removed or not.

    Man, it's glorious to turn those amps up!

    :dude
     
  10. Zacateca

    Zacateca Member

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    I am not sure if the bright cap being bypassed depends on the channel volume or on the master volume. If you want just some break up tone, that is channel volume around 10 o'clock with my rig, will the bright cap be bypassed? That is my main concern
     
  11. radicool

    radicool Member

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    I got around this issue by using a 2-output volume pedal. One output is controlled by the pedal and one is always on, probably meant for a tuner. I run my pedal board from the always-on output into the normal channel. The other output goes into the top boost channel, and is controlled by the pedal, allowing me to use as much or as little top boost as I want at any time. It works very well, and it's cool to have both channels combined if I want.
     
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  12. hacinador

    hacinador Member

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    In some Voxs circuits a bright cap is never fully bypassed. Why? There is a resistor (can be a 220K or 330K value) in series with a volume pot. And why it's no bypassable? Because when you set your volume pot at max, there is still the resistor that 'cooperates' with a bright capacitor. You can jumper the resistor and then the volume pot losts an interaction with the bright cap when the volume is set at max. But it will change a behaviour of the circuit a little...

    The best way is to try several values of bright caps in your amp. You can also make something like a 'bright cap switcher' to switch between 2 or 3 values. So easy! I don't know why there's no manufacture doing it. It would be so great to have something similar to Matchless 6-way bass switch, but with treble capacitors instead of coupling caps :)
     
  13. e-flat

    e-flat Supporting Member

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    Based on this description, I'd say that you'd really appreciate the bright cap mod. I did it to my AC30 CC years ago because I had similar experiences with dirt boxes (fizzy, brittle) and I haven't regretted it for a second.
     
  14. Coldacre

    Coldacre Supporting Member

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    do it! get rid of it!! it's a HUGE improvement.

    I used my AC15C1 for 2 years with the bright cap on. the top boost channel was always harsh with overdrive pedals..... unless the amp was completely dimed. but it's not practical to play it at that volume all the time.

    it was with some trepidation that I snipped it off. I was concerned that I would lose some top end to the clean sound. well I worried for nothing. the amp sounded exactly the same, no loss of tone.
    there were two noticeably improvements:

    1. suddenly overdrive pedals sounded better on the top boost channel. much better. what a relief!

    2. the treble control became a lot more interactive. there was now a usable sweep from 12 o'clock to 3 o'clock. prior to this there just seemed to be two sounds with the treble control: not enough or too much. this was an added bonus.

    once I read up on the fact that the original AC15's from the late 50's never had a bright cap, I realized that they are completely superfluous to the amps circuit.


    snip it.
     
  15. Coldacre

    Coldacre Supporting Member

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    I'd wager a bet that most of the people voting no haven't tried the mod for themselves.
     
  16. Zacateca

    Zacateca Member

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    This is really interesting. I was thinking about the bright switch installation but I have no experience doing this kind of stuff. I am tempted to do the bright cap snip instead. Thanks everyone for your advice
     
  17. illini

    illini Member

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    It sounds like you would benefit from doing it. The bright cap is on the channel volume not on the Master volume, so overall volume isn't the issue, but rather how much you are driving the channel volume. If you are running the top boost clean then the bright cap will be in the circuit making overdrive pedals sound fizzy. If you are using the Top Boost channel for it's gain, and have the gain past noon then the bright cap will be out of the circuit, and not worth doing.

    I did it and have never looked back. Amp does loose a tab bit of presence or sparkle on the Top Boost channel, but can be added right back in with a roll back of the tone knob one notch.
     
  18. metropolis_4

    metropolis_4 Member

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    Interesting; I wonder if that's why I never understood the reason for the mod. The only way I ever use my AC15 is on the top boost channel with everything set right at noon. I must have always had the volume past that point where the bright cap is out of the circuit
     
  19. coldengray

    coldengray Supporting Member

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    I bought one of these and returned it because it was so incredibly bright it was cutting my head off. I considered the bright cap mod but just returned it. I remove(d) the bright cap from my vintage style Marshalls now.
     
  20. deluxe83

    deluxe83 Member

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    keep it the way it is. Voxes dont play well with every pedal. Get a bassman style circuit for that. Push a vox with a dirty boost, and let it shine at what it does well!
     

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