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mmolteratx
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#241
+ and - with AC usually refers to phase and the wave's position relative to the relative zero axis.
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Arby911
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#242
Speaker + - is to help wire in phase, nothing more.
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mmolteratx
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#243
Quote by Arby911
Speaker + - is to help wire in phase, nothing more.


Yea, on my phone right now but that's what I was trying to say and for some reason couldn't articulate it. If you wire the speakers out of phase, they'll largely cancel each other out and you aren't left with much other than the slight differences between the two speakers.
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Dave_Mc
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#244


EDIT: wait hang on a minute you only have high school physics? from the first sentence/paragraph of your original post it sounded like you had a phd or something
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Last edited by Dave_Mc at Dec 30, 2012,
R45VT
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#245
Quote by dietermoreno

If Class D amp has no better frequency efficiency response than Class A amp, then why do the classes exist? Money making scam for amp merchants to scam you into blowing all of your money?


Buddy you have a lot to learn.

Audio is completely different than other applications. Its all about signal reproduction and low crossover noise.

Class "A" is very inefficient. Best signal reproduction.

Class "B" more efficient, more noise to the point its not used in audio.

And so on.....

the classes are there for reason. How old are you?
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CECamps
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#246
Quote by dietermoreno
My physics teacher has failed me then because this is what he told me. Maybe he was lying to me to make the discussion simpler for my understanding.


I can't speculate on your physics teacher's intent, but if he told you that a standard audio waveform is pulsating DC then I'm not sure if he should be teaching physics. Audio waveforms are AC.

Quote by dietermoreno
I have never heard of + and - AC? Do you mean there is an oscillation circuit in the speaker set to the 60Hz AC frequency that splits the AC positive wavepeaks into + DC and splits the AC negative wavepeaks into - DC and the speaker leads are + or - DC?


No, that's not what I'm saying at all. What I'm saying is that the speaker's voice coil, which is "housed" in the speaker's magnet and connected to the speaker's cone, is pushed outward and pulled inward by the AC current delivered to it. The physics of it are as basic as it gets in terms of electromagnetism. Think of the voice coil as an electromagnet with constantly varying polarity due to the changes in current flow direction which come courtesy of the AC waveform being delivered to it. The back and forth motion this causes makes the speaker cone generate sound waves. It's a transducer, transforming electrical energy into acoustic energy.

A speaker is a very simple device, and even a quick Google search can get you all the info you'd ever need to know about them.


Quote by dietermoreno
Well so more to the point of this thread, everything I was saying about frequency efficiency response as the cause for the amp to sound bad at low volumes is mostly or at least partially correct, right?


Performance at any volume is subject to how accurately delivered the audio waveform is, yes.


Quote by dietermoreno
If Class D amp has no better frequency efficiency response than Class A amp, then why do the classes exist? Money making scam for amp merchants to scam you into blowing all of your money?


The amplifier class is most closely connected with power efficiency. But varying classes have uses in all sorts of applications. Going back to the class D amplifier, since it generates a square wave it is great for pulse generators--particularly since it is theoretically 100% efficient.
Last edited by CECamps at Dec 30, 2012,
Cathbard
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Join date: Oct 2009
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#247
The class of an amp describes it's electrical function, it has nothing to do with grade or quality per se.
A, B, A/B and C are types of analog amplifiers. Class D is digital (sort of).
Class A amplifies the whole signal in one element.
Class B operates on 50% of the signal (you use two back to back to amplify the whole waveform).
Class A/B is like class B but there is some overlap between the two halves to minimise on crossover distortion.
Class C amplifies less than 50% of the signal, it isn't used for audio.
Class D is digital. It works by switching high power MOSFET's.

Class D is becoming very popular in bass amps and PA systems because it can produce massive power in a tiny, cheap package and both of those applications need lots of power.


I've oversimplified class D a bit. If you want to know more read this:
http://en.wikipedia.org/wiki/Electronic_amplifier#Class_D
As you can see, they are a totally different concept to A, B and C.
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Last edited by Cathbard at Dec 30, 2012,
TNfootballfan62
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#248
Quote by dietermoreno
I have encountered the same misconception with my friends who are musicians, so I joined this forum to give my 2 cents to give a better explanation more in depth explaining the electrical engineering concepts and physics concepts as they apply to the electrical engineering concepts so that everyone can understand this with the aid of Wikipedia to look up terms that they don't understand:


In the future, don't lead off posts from this position of authority, when you don't seem to have degrees or an education in either physics or electrical engineering. It's disingenuous, and gives way too much credence to a lot of incorrect information.
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AcousticMirror
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#249
You should really get your money back from your physics professor because he seems to be edison in disguise and does not understand how alternating current actually works.
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R45VT
Doesn't speak guitar
Join date: Dec 2009
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#250
Quote by AcousticMirror
You should really get your money back from your physics professor because he seems to be edison in disguise and does not understand how alternating current actually works.


Tesla FTW.
Quote by DeathByDestroyr
See, it's important that people clarify when they say "metal", because I pretty much always assume they are a Cannibal Corpse fanboi.
Arby911
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#251
Quote by R45VT
Tesla FTW.


Indeed! Tesla was a better scientist, inventor, intellectual etc..

Edison was better at sales, stealing shit and marketing.

Both of them were far smarter than I am.
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R45VT
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#252
Quote by Arby911
Indeed! Tesla was a better scientist, inventor, intellectual etc..

Edison was better at sales, stealing shit and marketing.

Both of them were far smarter than I am.


x10. Most people don't have a clue who he is and what he did. Sure Edison had the light bulb but if we had it his way we would have sub power stations every block or two.
Quote by DeathByDestroyr
See, it's important that people clarify when they say "metal", because I pretty much always assume they are a Cannibal Corpse fanboi.
Cathbard
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#253
Radio too. Marconi was using Tesla's patents to do what he did. The court eventually ruled in favour of Tesla.
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DeathByDestroyr
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#254
Quote by Arby911
Both of them were far smarter than I am.

It's not really so much a matter of intellect, as it is timing and ambition. Someone was bound to put some of those together, and as far as I see, could just as easily have been many of us, given a similiar environment.



Ya'll are funner than this Nikola fellow anyways, he just doesn't have much to say now days.
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Last edited by DeathByDestroyr at Dec 30, 2012,
R45VT
Doesn't speak guitar
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#255
Quote by Cathbard
Radio too. Marconi was using Tesla's patents to do what he did. The court eventually ruled in favour of Tesla.


Yup


And Tesla died broke didn't he? Gave up his patents for WestingHouse to succeed.
Quote by DeathByDestroyr
See, it's important that people clarify when they say "metal", because I pretty much always assume they are a Cannibal Corpse fanboi.
mmolteratx
UG God
Join date: Sep 2008
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#257
Quote by R45VT
Yup


And Tesla died broke didn't he? Gave up his patents for WestingHouse to succeed.


Yes. And according to that link in the last post, the ruins of Wardenclyffe Tower are for sale. $1.6 million. Tempted.
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cdr_salamander
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#258
I wouldn't quote that dude in my sig if he wasn't worth quoting. Smart fella.
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gumbilicious
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#259
Quote by dietermoreno
If Class D amp has no better frequency efficiency response than Class A amp, then why do the classes exist? Money making scam for amp merchants to scam you into blowing all of your money?


afaik each class of amplification is another way of implementing an amplification circuit. efficiency is just an evaluation of the implementation. a higher class does not necessarily mean a higher efficiency, and some amplification classes have some serious tradeoff with fidelity and efficiency (class C for example).
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#261
I must admit I have not read all 259 replies to this topic but, you would be amazed at the sounds I can get out of a Mustang I and a valve jr. through my Mesa 2x12 with Force 12's and a couple of pedals. I don't even power up the 60 Supersonic head unless I'm at a gig
Maineguitarist
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#262
Whelp, my brain hurt after reading. That's a good indication that I learned some pertanent information. Thankks mans
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#263
Thank you so much for posting this.
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Ian_the_fox
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#264
Just wanted to post this here:


Played an open mic today doing lead guitar over a friend's acoustic, had my JCA running with volume at 1 with some delay in the loop, mic'd up. Some guy complimented me and said I had the best lead tone he had ever heard. No joke.

Next person who says it's impossible to get a good sound out of any 100w tube amp at a low volume I am going to personally track down and slap them upside their head.
tubetime86
I don't even play guitar.
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#265
Quote by Ian_the_fox
Just wanted to post this here:


Played an open mic today doing lead guitar over a friend's acoustic, had my JCA running with volume at 1 with some delay in the loop, mic'd up. Some guy complimented me and said I had the best lead tone he had ever heard. No joke.

Next person who says it's impossible to get a good sound out of any 100w tube amp at a low volume I am going to personally track down and slap them upside their head.

Got a time machine?
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Arab_Philosofer
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#266
Quote by darkwolf291
It's well known that Edison stole and patented a bunch of Tesla's, among others, intentions.

Edison was a bastard, he tried to conglomerate cinema right from the beginning. He actually hired goons to destroy equipment and assault early filmmakers during their filming endeavors. Can't deny his intelligence of course.
Phoenix V
Registered MUser
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#267
Craig

Thank you

Thank you

Thank you

The amount of misinformation about low volume and tone is enormous.

This is a great respository of information on this topic. Everyone should read.
'It takes 100 guitar players to change a light. One to change the light and 99 to stand around pointing, saying..."Yeah man, look...I can do that too"...'

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jakey333
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#269
I really enjoyed reading this. I run a Hiwatt 100w DR103 at all times, and people say that's just about the loudest 100watter amp in the world.

It can be if you need it to be but....

Thing is, it's totally clean, so I can get great tones out of it due to the headroom, even at 3 and 4 on the volume controls.
Adrian Curran
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#270
My experience in recent times has been one of being told by the sound engineer to turn away down. So in small/medium sized venues were you are being miced up through a PA it seems to be a waste of time and money having a high powered amp. Although, we are guitar players so what makes sense is not always what guides us!