Talk me out of/into a VOX AC30 (and some dB discussion)

Discussion in 'Amp Central Station' started by Polderpatat, May 22, 2019.

  1. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    Interesting looking at db measurements with a 4w amp.

    Speaker efficiency is measured at 1w 1 meter.
    A 93db rating is a low efficiency speaker, and a 103db rating is high efficiency.
    That is a 1 watt signal sent into the tested speaker, producing 93db or 103db at a distance of 1 meter from the speaker.

    Puts some perspective on your 65db cleans for Here Comes my Girl etc.
    Amps are supposed to be rated at clipping, or at the highest clean output, where it just starts to distort. So an AC4 should put out 4w of clean power, or maybe 3w to be sure it's really clean.
    65db kind of suggests the AC4 can't even put out 1w of clean power.

    A lot will vary in the testing method, but one thing I really wonder is what people mean when they say "loud"?
    Also of course rated clean output can vary.
    I have not compared the two amps side by side but I've been told an AC30 is of comparable volume to a 50w Marshall. Likely the AC30 would have efficient Blues and the Marshall would have less efficient speakers.

    WRT some claims that an AC30 is awfully bright and hard to dial in lower volume tones, while others claim an AC30 is easy to dial in lower volume tones, the speakers play a huge role including the age of the same model speakers.

    A fresh alnico Blue is harsh and strident, while a well used Blue is fat and sweet.
    New amps in shops are likely to come with new speakers that are still harsh and strident, until they've been played fairly loud for 30-40 hours.

    I suspect amps are often judged based on the speakers.
     
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  2. bo

    bo Friend of Leo's

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    Doesn't the new 1x12 variant (Top Boost channel only) have a master volume? If so that would be a consideration. The AC15 would be the other. There are plenty of Vox variants out there. As for the classic style AC30, yes they "can" get ice picky. You have to get used to the EQ controls, which can be infuriatingly interactive (I love how some try to sell that as a feature). They're very loud and not good for typical home use. When you get home from a gig in the wee hours (likely after having been told to turn down all night...) and have to haul it inside you're suddenly reminded why it has THREE handles on top. As mentioned earlier, I'm one of those people that let mine go.
     
  3. Doctorx33

    Doctorx33 Tele-Afflicted

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    I don't gig anymore. I have an AC30CC2. I don't play clean, I don't do chime. I use an attenuator when I dime the amp. It also has a master volume which works pretty well, but I still prefer the attenuator.

    As far as the blues vs the wharfdales, I don't think one is better than the other, they are just different. The wharfdales actually have a better low end.
     
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  4. gusfinley

    gusfinley Tele-Holic

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    Which AC15 model was this? A modern AC15 with top boost or classic EF86 AC15 circuit?


    This is a great testimonial to the AC4C1-12! I would really like to get one, but already have a DIY AC4 top boost / EF86 and a AC4C1-BL that I converted to a handwired circuit and spare parts to build another. Have you removed the C20 bright cap on your AC4C1-12?
     
  5. Polderpatat

    Polderpatat TDPRI Member

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    Yes but the AMT is very loud, even for 50W solid state, the power amp never distorts even with full volume, the dB ranges are just at what volume I feel comfortable, not to loud to deafen me over time, but enough to fill the room.
     
    Last edited: May 23, 2019
  6. Polderpatat

    Polderpatat TDPRI Member

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    It is an alternative for the electrovoice speaker thatw as put in old mesa thiele cabs, you can find a lot on forums about the speaker in that context :)
     
  7. Norris Vulcan

    Norris Vulcan Tele-Holic

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    I have an AC30.
    I use it mostly at home, for clean sounds and pedals.
    I use an Attenuator :cool:
     
  8. Sean Mac

    Sean Mac Tele-Meister Ad Free Member

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    The output transformers are interesting to compare...

    output transformers.JPG

    on the left is a Drake 784 139 50W Marshall and the right is a new steves025uk JMI AC30.

    They are close to identical in size :)
     
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  9. Lawdawg

    Lawdawg Tele-Meister

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    @telemnemonics hit the nail on the head with the post regarding the relationship between tube amp wattage and clean headroom.

    Yes an AC30 is probably too much amp for most housing arrangements, but if you're not playing out a lot and aren't looking to crank it into tube distortion it's really not necessarily impractical especially since the OP is interested in clean tones.

    My two amps are a SF Twin and a Hayseed 30 (an AC30 clone) -- both of which are famously loud amps. That said, I've got a big basement to play in, I don't run them full blast, don't need to lug them to gigs anymore, so they suit me just fine and sound glorious. Full disclosure -- both of these amps have a master volume which I view as a useful feature and not a bug. Contrary to popular belief, you don't need to run a Twin or AC30 wide open to get some fantastic tones.
     
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  10. Mad Kiwi

    Mad Kiwi Friend of Leo's

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    Actually from other posts you've mentioned this in, I meant to ask you about that.

    Given you've said (from memory) the brightcap is in for low volume playing, do you think I need to if I most often play with gain and volume between 11.00 and 2.00 o clock on the dial?
     
    Last edited: May 23, 2019
  11. gusfinley

    gusfinley Tele-Holic

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    Its hard for me to say what you might like. All I know is that removing the bright cap makes the amp's tone stay relatively the same at all volumes - instead of dumping more highs into a top boost circuit (especially if played through with a tele). I played my AC4C1-BL for about 10 minutes, then searched for a schematic to see what was wrong with it and found the bright cap. I ripped it out and was much happier with the tone. I played it side-by-side with my Pathinder 15 -> AC4 conversion into a panning pedal and they sounded very similar.

    If you're keen with electronics and have a 100pf cap on hand (or can easily get one), it'll only cost you some time.
     
  12. OldDude2

    OldDude2 Tele-Meister

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    Gus - I have an AC4C1-12 CAN YOU elaborate more?
     
  13. Nickfl

    Nickfl Tele-Afflicted

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    FWIW, I've found those smartphone db meter apps to be questionably accurate. I tried one on my last phone (a Samsung) and it seemed to max out at about 90db and only registered that high when I put it three feet away from a cranked vibrolux reverb, which was certainly producing a much higher volume than that. For comparison, I used an actual db meter to measure my AC4c1 once before I sold it and I was easily getting readings over 100db (though this was with the meter pretty close to the amp as I recall). I could never get the smartphone app to register anything over 100db. I haven't tried with my current phone, but I suspect it depends greatly on the quality of your phone mic and how well the app works with it...
     
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  14. TokyoPortrait

    TokyoPortrait Tele-Holic

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    Hi. Thanks for the info.

    So, I don"t know much about this kind of stuff. For future reference, should I (we) measure dB at 1m? I measured it at 2m, since that was what the OP did. Any idea if that 1m will make a difference?

    I see. 65dB was what I got at a setting that I was thinking wold be indisputably clean. What I personally still would consider clean but with character (rich or complex or full or meaty or developing, if any of that makes sense*), was averaging more around 73 - 75dB. Don't know how much difference that extra 8 - 10dB make.

    I'll add my testing 'method' was anything but rigorous. Just an app - who knows how accurate? But, same app as OP, so maybe comparable in that regard. Phone on a box on a chair directly on level and in line with the speaker cone, mic hole facing the cab.

    And yes, like clean, what does loud mean? Yesterday, I felt like the amp was noticeably quieter than I remember it being the last time I had it cranked, which was months ago with the old, original values in it. But yeah, my 'feeling' doesn't really mean anything concrete.

    Thanks.

    Pax/
    Dean
    * man, words just ain't enough...
     
  15. TokyoPortrait

    TokyoPortrait Tele-Holic

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    Lordy, back again.

    So, I just found this. Vox AC30 at 6:14 and Twin at 8:05.



    Is this what people mean by clean? And, in case it's a different question, is this clean at clipping / just where it starts to distort?

    I know this all sounds dumb / should be obvious / etc.,* but as I stated yesterday, the more I think about this, the more I hear and the more I doubt.

    Thanks.

    Pax/
    Dean
    * or maybe not, if this is a place you always dial right on past...
     
  16. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    Interesting stuff.
    I guess measuring the db from a distance of 1 meter would be most comparable to some sort of standard, but here we're discussing more of a general sense of loud and clean and home, all of which vary from one player to the next.

    For me I find even my two AC30 based amps run out of clean headroom at home.

    I don't know where the hell people get this idea that our home is a prison where we are not free to play electric guitar. Crazy.
    Have a conversation with the loved ones!
    Tell them: I love playing electric guitar!
    Ask them when they will tolerate doing the thing that I love!
    Or when will they be away?
    If the loved ones will not tolerate what I love, what am I doing there?

    My rant isn't directed at you here, just in general.

    Measured db has use in the discussion too, I think it's interesting and would be curious to know what you get at 1m.
     
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  17. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

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    Hard to really tell from the playing, the Vox sounded less clean than the Twin, which almost sounded like the Strat mic'd with no amp.
    Odd comparison of amps, volume was up and down from one amp to another, he set the controls by looks rather than sound.

    I guess those were all clean sounds, but he didn't really play the amp sounds, more kept zipping around on the guitar so the tone was all a series of note attacks, seldom the sound of the amp ringing out.

    I agree though that clean is not well defined.
     
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  18. TokyoPortrait

    TokyoPortrait Tele-Holic

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    Hi. In truth, same with the AC4. But, that might be because it doesn't really have much :) But I find that a strength. I can get juicy goodness at relativley low volumes.

    Depends to some degree where you live I suspect. I shudder to think of the protocols and social responsibility ethics breaches I commit living here in Japan and playing loud at home. I live on the edge of rural, backed on one side by a small field and then a golf course and I'm also a fair distance from the neighbours on the other three (10m or more from my study where I play). So, I'm lucky. My AC4HW was too loud for the guy I bought it from, as he lives in an apartment.

    Oh, & don't worry. I wasn't taking it that way as I was reading it.

    Me too. I'll try again soon. Home today with a dodgy knee. But, I still have work to do. So it might not be for a few hours. Oh well...

    Laters.

    Pax/
    Dean
     
  19. Rob77

    Rob77 Tele-Meister

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    Personally I've owned 2 types of AC30's - JMI & Handwired, and played and recorded with the Standard CC models All I can say is that they ALL sound, feel and perform differently.
    For the clean chimey sound my JMI wins hands down, but is fussy with pedals. The handwired took pedals really well and was my main gigging amp before I decided to sacrifice tone for my back.
    The standard CC models were impressive and took my pedals well, but preferred the HW.
    Yes they are heavy, and if you want to turn it up to the sweet spot, yes too loud for home.
    I also use an AC15HW and can say theres less headroom than the 30, but its all subjective on how loud you want to play. For carting around to gigs, the AC15 honestly doesn't feel that much lighter.
    All great amps and have their uses. Wish you all the best!
     
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  20. TokyoPortrait

    TokyoPortrait Tele-Holic

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    Hi.

    Not a new vid, but you could try asking in the comments.

    And, I reckon for that kind of clean, my AC4HW1 won't be loud enough for you. But, see my next post for the caveat.

    Pax/
    Dean
     
    Last edited: May 24, 2019
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