a few general amp questions...

general questions, comments and ideas about recording, audio, music, etc.
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frank
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a few general amp questions...

Post by frank » Sat Nov 20, 2004 4:45 pm

...guitar amps that is. some of the questions aren't really related, may have come up before(couldn't find 'em in a search though), and may just plain sound dumb...but maybe they will spark smarter questions/answers

here goes:

-so what is the difference between "tube" watts and "solid state" watts? I mean why does a 15watt tube amp crank out what seems like more volume than a SS amp?

-how does one blow speakers and/or melt down an amp? playing too loud, or with too much bass, or both? I mean, theoretically if I play guitar through a small bass amp cranked, I can't hurt it right? or can any amp be pushed to the point of self destruction?

-how do I determine the output of a solid state head that I have? it has absolutely no lables/info in or on the amp. can I use a multimeter?

-if my guitar pickup's output is really low and just turning up the amp adds a ton of hiss, what should I do? will boosting with an EQ pedal just boost the noise too?
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Scodiddly
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Re: a few general amp questions...

Post by Scodiddly » Sun Nov 21, 2004 6:01 am

1. A tube amp will still sound OK/musical when cranked up into distortion, while a solid-state amp will sound nasty.

2. Blowing speakers is the most common failure, although there are other possible "too-loud" failures. Assuming the components are reasonably well matched for power-handling (so the speaker doesn't jump out of the box on the first power chord!), overheating is the usual problem. Speaker coils can overheat and gradually come apart, tubes can overheat, and tube output transformers can overheat.

3. W = V^2 / R, so if you measure the output voltage while feeding an 8-ohm speaker, you'll get pretty close to an accurate reading. I.E. you measure 10 volts, so 10^2 = 100, and 100/8 = 12.5 watts. There are all sorts of issues with peak-to-peak vs. average vs. rms voltage readings, but you'll be close enough for most purposes.

4. Maybe. If the amp's input is too noisy for a very weak pickup (and you might look into why that pickup is weak...), then an EQ or maybe a boost pedal with quieter circuits will be able to bring up the level without adding much hiss.

frank
takin' a dinner break
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Joined: Mon Jun 02, 2003 10:26 am
Location: Brooklyn, NY

Re: a few general amp questions...

Post by frank » Sun Nov 21, 2004 8:10 am

awesome! scodiddly...you always come through.

thanks,

frank
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jajjguy
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Re: a few general amp questions...

Post by jajjguy » Sun Nov 21, 2004 4:45 pm

frank wrote:-if my guitar pickup's output is really low and just turning up the amp adds a ton of hiss, what should I do? will boosting with an EQ pedal just boost the noise too?
there are pedals made just for this, such as the zvex super hard on, or the klon centaur.

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ryangobie
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Re: a few general amp questions...

Post by ryangobie » Sun Nov 21, 2004 4:49 pm

i remembered reading this on the geofex site...up on the tube amp FAQ

Are Tube Amps louder than solid state amps of the same power?
No. However they do SOUND louder. Let me explain.

Some excellent scientific work on tube preamplifiers and their distortion products has turned up the mechanism for this. When tubes are driven outside their linear region, for the first 12db or so of overdrive the harmonics that they produce trick the human ear into thinking that the sounds are getting louder, when in fact the sound is getting progressively more distorted.

It is this acoustic trick that can make tube amps sound up to 12db louder than they actually are compared to a perfect, undistorted amplifier. A solid state amplifier of the same power as a tube amp may distort at the same signal level as the tube amp, but the distortions are not subtle, and we hear them as distortion, not as a slightly louder sound. A solid state amplifier of much greater power would remain undistorted at higher levels, and the tube amp would sound comparably loud to the larger solid state amp.

They sound larger than they are.
weeeee

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