Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Electric guitar amp speaker rounding

  1. Mar 9, 2005 #1
    I figure electric guitar playing physics people might know how to answer this.

    Can speaker rounding be achieved at lower volume levels, without going to a low power amp?

    I have a 60 watt combo with one 12" speaker rated at 70 watts. It can get pretty loud when I try to get that nice full roundness. It's a modeller so I can get some decent sounds at lower volume, but I want to get rounding at volumes that won't disturb the neighbors.

    Is this possible? Or is true rounding only achieved if the speaker is driven?
     
  2. jcsd
  3. Mar 9, 2005 #2

    brewnog

    User Avatar
    Science Advisor
    Gold Member

    Hmm, good question!

    I'll say that I'm not the most qualified person to answer this, but I'll offer the following:

    You really do need to drive a speaker hard to get rounding. You could use an attenuator to 'soak up' the power so that you can crank the amp up, but I think people only tend to do this with nice big tube amps (and I'm guessing you're using solid state). The problem with attenuators is the more you put into it, the worse the tone output gets.

    You could also try an isolation cabinet, which has the effect of putting your hi-fi in a wardrobe, if you know what I mean.

    You can get one of those nice valve pedals, so you're getting some nice sweet valviness before you've even gone through the pre-amp.

    I use an 80W Marshall Combo, solid state. It stays pretty consistent throughout the whole range of volumes, especially on the 'crunch' channel, but being solid state (and none of your fancy digital modelling) it lacks the warmth of a valve amp. I'd trade it in any day for a much, much smaller valve amp.
     
  4. Mar 9, 2005 #3

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    This is a perennial problem for guitarists, and it unfortunately has no real solution.

    The "roundness" or warmth you seek in your tone comes from both the amplifier itself and the speaker. Neither device is linear, and both color your sound.

    The color from an amplifier is largley due to a tube preamp. Since you say you're using a modeller, I assume your amp is totally solid-state. As a result, there's no color to be found at all -- besides the modelling effects, your amp is probably a very, very linear device. That means that most of the warmth you like at high volumes is probably coming from the speaker itself, and there's frankly no way to get it on your amp without those volumes.

    brewnog makes an excellent suggestion -- you can buy a 12AX-7 tube in a pedal, and put that before your amp, or in its effects loop, and it might give you the warmth you seek. Your only other option is probably to look for a new amp that suits your tastes better.

    Keep in mind that 60 watts is pretty huge! Most amps that have high output power are designed to sound best at high volumes, since that is their intended operation. You shouldn't use a stage-worthy stack at practicing volumes and expect it to sound that great -- almost none of them will. You might want to look into a small 15W head or combo that's really designed for practice in mind.

    - Warren
     
  5. Mar 9, 2005 #4
    It does have a valve in the preamp. It's a Behringer AC112 This does work to get a nice warmth, reducing the clipping of pure solid state.

    Instead of a cabinet, wonder what putting a blanket over just the front of the cabinet would do? Probably too muffled.
     
  6. Mar 9, 2005 #5
    Sorry about leaving out the preamp tube in my description. I actually get some pretty decent tone at low volume, (I also turn the cabinet toward a wall, which seems to help reduce the volume projected.), but I was wondering if maybe tweaking the master volume could effect speaker rounding or if you really have to drive the speaker to higher volumes.
     
  7. Mar 9, 2005 #6
    Just curious, cause i don't know since i almost exclusively play acoustic, But what is speaker rounding anyways?
     
  8. Mar 9, 2005 #7

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    It's hard to say, Artman, because it's impossible for you to tell us exactly what it is about the tone that you like. It's quite possible that the tone color you're seeking is caused non-linearities in the speaker itself -- if so, it's not possible to obtain that color (on that amp) without loud volumes.

    - Warren
     
  9. Mar 9, 2005 #8

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    "Clipping" is the name given to exceeding a solid state amplifier's power capability. If you turn up the volume too far, the amplifier can't handle it, and the tops and bottoms of the waveform get cut off, as if you used a pair of scissors on them. A solid-state amp is not graceful at high volumes -- it can produce nice clean linear speaker output up to a certain volume (voltage), but it cannot go even a bit further. It's a brick wall. It sounds nasty, and no one likes it.

    The analogous phenomenon in a tube amp is called by a number of names, including "rounding." The tube fails much more gracefully at high volumes -- its power capability gradually tops out, and its output gently slopes off, rounding off the tops of the waveform, but not brutally clipping them. It sounds magical, and everyone loves it. It's distortion caused by surpassing the amp's capability, just like clipping, but it's responsible for every full, rich sound from Hendrix and Cream to garbage like Jet.

    - Warren
     
  10. Mar 9, 2005 #9
    As chroot said in his post several things effect how an electric guitar amplifier sounds. The preamp (effects, reverb, drive levels), whether it's solid state (transistor) or valve (vacuum tubes), the cabinet, the power amp, and the speaker. There are other factors such as the room, but just confining ourselves to the combo amplifier.

    Speaker rounding is a fullness that happens when the speaker gets pushed. It's not really distortion, more of a fullness. I think a good example of a clean speaker rounding can be heard in early beatles songs such as "I Want To Hold Your Hand," right in those first couple of chords.
     
  11. Mar 9, 2005 #10
    I always thought rounding was part of that, but more of just the speaker coming into its own, such as in the early Beatles and some Motown type guitar work. That is what I am trying to get anyway. Just at the threshold of distortion.
     
  12. Mar 9, 2005 #11

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Well, yes, speakers are non-linear devices with gradually sloping power limits (unless you hit the mechanical excursion limit, of course), so they perform their own kind of waveform rounding.

    Speakers always seem to sound best when they smell worst -- i.e. when the voice coils are so hot they're slightly melting the adhesive. :smile:

    - Warren
     
  13. Mar 9, 2005 #12

    brewnog

    User Avatar
    Science Advisor
    Gold Member

    Yup, a number of artists actually liked to physically damage their speaker cones before recording, to get their desired tone. I think T-Rex did this quite a lot; they used to poke pens through the cones in recording sessions.

    Very little, seriously. Also, the suggestion of turning the amp towards the wall will probably just annoy the neighbours, and isn't really addressing the problem!

    I've seen plans to make an attentuator somewhere, pester/pressure/bribe me and I might try and find the link.


    I'd love to be able to swap my 80W Marshall for a 30W Orange, any takers? :smile:
     
  14. Mar 9, 2005 #13
    My Behringer is really a very sweet sounding amp. It does sound good played quiet, just not fully rounded. I do have a little 15 watt Fender Rumble that is a solid state bass amp that I use for my bass and as a practice or small room guitar amp. It sounds okay played soft, but not as good as my Behringer.

    They both sound better than my Gorilla GG-60. :yuck: That was over powered, harsh and just never seemed to round out.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Electric guitar amp speaker rounding
  1. Guitar Songs (Replies: 17)

  2. Ultimate Guitar Amp (Replies: 20)

Loading...