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class A power amps and how they work?

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Nigel: I was referring to the guitarists habit of driving every amplifier into distortion mode. If they do this with a class A transistor amp, I'm sure they wouldn't like the sound.

You don't drive transistors amps, of any type, in to distortion :D

I didn't ask my friend about songs made with a class A transistor guitar amp, as you said, there are none. He will reply with a list of songs made with class A valve amps. However, if cracken says he does not wish to examine some class A guitar sounds, I will stop this apparently intrusive and unwelcome contribution.

I just don't see the point in it?, it's a valve amp - the fact it's class A makes no difference, it's got no relevence at all.

But if you want to find class A valve amps, look for 3W or 5W examples - there are numerous ones using an EL84 in single ended output - any push-pull ones will be much higher outputs.
 
They do sound VASTLY different from Class AB when overdriven.

For one class A valve amps don't sag as total current draw is always constant unlike Class AB. Second off you don't have crossover distortion in a Class A design either. Furthermore, it's much easier to saturate an output transformer on a Class A design than it is on a Class AB design. If it's a perfectly center biased Class A amp you don't have any asymmetry in the output...there's a myriad of factors at work here.

audioguru said:
Distortion is high frequency harmonics. But most guitar musicians are deaf to high frequencies.

I beg to differ. Care to elaborate?
 
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Nigel, I don't care if you see any point to this. I am not trying to help an ancient audioplile understand rock and roll. I'm trying to help cracken build his background knowledge about guitar amplifiers before he spends time and money building something without knowing what to expect out of it.

The reply I got about class A musicians is thus:
Jimmy Page (Led Zeppelin), first three albums
Neil Young, everything he plays every time he plugs in
Brian May (Queen) Only plays a stack of Vox AC-30's
Billy Gibbons (ZZ Top), likes the old Aloha's (made in the supro factory)

Now, cracken can either realize that he has heard class A amps, go listen to some of this music, or ignore me. I only hope Nigel ignores me.
 
Brian May (Queen) Only plays a stack of Vox AC-30's

AC30s ARE NOT Class A. Here's a great article from Randall Aiken that illustrates this.

**broken link removed**
 
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Most people with normal hearing cannot stand the severe distortion produced by those old geezer electric guitar players.
The deaf old geezers cannot hear the distortion they produced.

Their amplifiers were overdriven so they could hear anything.
 
So you assume that all of us rock n' rollers here are "old geezers"?
 
So you assume that all of us rock n' rollers here are "old geezers"?
Definitely!
The Beatles (I know they were not rock but were pop instead) were on TV a couple of nights ago. The picture was in black and white, the distortion was awful and the frequency response stopped at only 3kHz. I heard it the same on my AM radio about 47 years ago (!).
 
Definitely!
The Beatles (I know they were not rock but were pop instead) were on TV a couple of nights ago. The picture was in black and white, the distortion was awful and the frequency response stopped at only 3kHz. I heard it the same on my AM radio about 47 years ago (!).

Well I guess if you consider age 30 to be "old geezer" you would be correct.

Now...you think ALL of the distortion on that recording was because of the guitar amps?
 
A few minutes ago I heard the first recording of a human voice. It was horrible. Just grunts, groans and squeaks. In the 1960's the recordings were not much better.
In the 1960s I worked for Philips when they invented cassette tape. Then they made it much better. It produced fantastically clear and wideband recordings. But guitar recordings still sounded awful.
 
There's tone reproduction and then there's tone creation. Guitar amplifiers fall under the "creation" category while PA equipment, studio recording rigs and stereo systems fall under the "reproduction" category.

Obviously with equipment that's made to reproduce you want things to be as pure and transparent as possible. However, with gear made to create a sound, it's up to the individual player as to what they like.

Listen to this recently done AC/DC tone...very pleasant raw all valve guitar tone...and it's plenty distorted. ;)

YouTube - AC/DC Hail Caesar live from MADRID 1996 HQ
 
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AC/DC tone:
I hear square-waves from the over-driven guitar amps and screaming from the "singers". It is noise, not music.
 
AC/DC tone:
I hear square-waves from the over-driven guitar amps and screaming from the "singers". It is noise, not music.

That's kinda funny how you can supposedly hear stuff that isn't even there. I guess your ears must be better than any scope on the market. ;)

At the level at which they're overdriving those amps they're not even close to full on square waves. Moreover...at what frequency can you supposedly hear square waves?

You really must not be a guitar player if you perceive that as "noise".
 
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I am not a guitar player. I like listening to non-distorted live and recorded acoustic guitars, not the severely distorted square-waves from over-driven electric guitar amplifiers.
But I noticed that the recording you posted cut high frequencies above about 4kHz so it sounds like a lousy AM radio.
 
I am not a guitar player. I like listening to non-distorted live and recorded acoustic guitars, not the severely distorted square-waves from over-driven electric guitar amplifiers.
But I noticed that the recording you posted cut high frequencies above about 4kHz so it sounds like a lousy AM radio.

Thank YouTube compression for that. Moreover, guitar speakers only work within the 70Hz - 5kHz range anyway...which is more than the usable pass band for guitar frequencies (82.41Hz - 1.32kHz at the fundamentals, leaving plenty of room for upper harmonics).

Not to sound rude, but the OP started this thread in regards to wanting to build a guitar amplifier capable of obtaining overdrive. If you're not a guitar player and/or don't like "that sound", then what are you doing on this thread? It's not "noise"...it's just a different sound. Different strokes for different folks...some like it some don't. We like it...you obviously don't. And while that's not a bad thing, we do find it rather insulting when people who don't like that sound come onto a forum and trash what we like just because they personally don't like it. While we're not into the "clean acoustic guitar sound", out of respect for those who do like the "too clean, perfect and mellow sounding" stuff we wouldn't come on here trashing that.

You don't have to like it...but that doesn't mean come on here and show disrespect towards those who DO like it.

For the record some of us are quite younger than you...which hardly qualifies us all as "old geezers". ;)
 
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It is obvious that you are deaf to the high frequency harmonics of sound that is produced by severe distortion.
I am old but some "electric guitar music" is older than me. It sounds awful today because I can still hear high audio frequencies and my high quality speakers produce them.
Your "70Hz to only 5kHz" is the awful muffled sound of an old AM radio. Normal people hear frequencies up to 20kHz.
Old geezers and you cannot hear the high audio frequency harmonics called fuzz.
 
It is obvious that you are deaf to the high frequency harmonics of sound that is produced by severe distortion.

I have no idea where you got that from. If you re-read my post -

Jon Wilder said:
Moreover, guitar speakers only work within the 70Hz - 5kHz range anyway...which is more than the usable pass band for guitar frequencies (82.41Hz - 1.32kHz at the fundamentals, leaving plenty of room for upper harmonics).

That is to state that the normal frequency range that a guitar speaker itself is designed to work in is between 70Hz - 5kHz. This had nothing to do with my hearing, but everything to do with the frequency pass band that the speaker itself responds to at the -3dB (half power) points. It's a 12" speaker...what more do you want from it? Look at the frequency response specs for a typical Celestion guitar speaker sometime. ;)

The reason I don't hear the "fuzz" is because I know how to properly tailor the voicing an overdrive circuit. A well voiced overdrive circuit for guitar does not distort all frequencies within the pass band the same amount. The proper way to do it is to shelve the highs and lows early on in the circuit to keep them from getting clipped and focus on overdriving the midrange area of the spectrum. This keeps things nice and smooth in the highs yet nice, tight and punchy in the lows.

audioguru said:
Your "70Hz to only 5kHz" is the awful muffled sound of an old AM radio. Normal people hear frequencies up to 20kHz.

Not if the frequencies aren't there in the first place. Or in the case of building an overdrive circuit you may wanna shelve out the high highs again to keep them nice and clean while everything else below that gets clipped.

Rock guitar is a very mid-range sound. Add those upper highs to it and it's not a usable sound. The sound of rock is a "powerful" sound. It's supposed to sound "big and full" more than it is to sound "loud". It's a sound that hits you...all about impact and sounding "big and full"...not "clean and chimey". As such most of us rock guitarists are actually quite sparing on the highs to keep those upper frequencies from becoming overbearing, which keeps things sounding nice, big and smooth rather than harsh and tinny.

I know you're a hi-fi enthusiast...however in the world of electric blues and rock and roll, guitar and hi-fi do not mix. They never did. It's a completely different world. You may not like it...and as such you may not fully understand it. But it is what it is, it's the sound we like, and that's that. Furthermore, not every instrument in a band is supposed to cover the entire audible frequency spectrum in a flat nature. If they all did we'd have one hell of a time trying to place each one in the mix.

For the record we humans don't even hear flat and the frequency pass band that our ears respond to changes with volume, becoming less sensitive to lows and highs at lower volumes (Fletcher/Munson curve).
 
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You mentioned a Celestion speaker for rock guitar music. Did you see its horrible frequency response?
Nothing below 100Hz.
A null at about 1.5kHz.
A peak from 2kHz to 5kHz then a sharp drop above so that all the important high frequencies are missing.

It makes a sound like a muffled buzzer, especially when its amplifier is clipping. [/b]Real[/b] music has no distortion and has wideband frequencies.

Maybe you have never heard a recording of a symphony orchestra. It should have no distortion and have wide bandwidth. If your amplifier and speakers are good then it sounds the same as live.

An amplifier with distortion has a difficult time trying to sort out the frequencies and makes millions of harmonics that cause FUZZ.
A modern low distortion amplifier has no harmonics that are caused by distortion and has a wide bandwidth to produce the harmonics of the music. The high frequencies of the music "sizzle".
 

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You mentioned a Celestion speaker for rock guitar music. Did you see its horrible frequency response?
Nothing below 100Hz.
A null at about 1.5kHz.
A peak from 2kHz to 5kHz then a sharp drop above so that all the important high frequencies are missing.

It makes a sound like a muffled buzzer, especially when its amplifier is clipping. [/b]Real[/b] music has no distortion and has wideband frequencies.

You're focusing on ONE INSTRUMENT. When you hear music as a whole, it encompasses an entire band. The band as a whole will cover the entire spectrum. But each instrument alone by itself will not...and you wouldn't want them to.

I used to run sound for a living...and like most sound engineers you end up having to pull certain frequency bands out of certain instruments (like shelving 80Hz and below out of guitar and vocals because there's nothing down in that range that's usable to those instruments) in order to place them in the mix where they belong. Drums are mainly sub low frequencies and high frequencies. Bass guitar the same. Guitar and vocals fit in the mid band with vocals extending into the high pass band. Together as a whole they will encompass the entire spectrum.

If each instrument covered the entire 20Hz-20kHz spectrum, you'd have instruments burying each other in the mix. The fact that they DON'T cover the entire spectrum in the mix is what allows the human ear to discern one from the other when they're played together. ;)

audioguru said:
Maybe you have never heard a recording of a symphony orchestra. It should have no distortion and have wide bandwidth. If your amplifier and speakers are good then it sounds the same as live.

Again..this is the "big picture"...not just one instrument in the orchestra. And even then you have certain instruments that cover only a certain pass band. Cellos are lower in frequency range than violas and violins. Upright bass is lower than everything else. Alto and soprano saxophone cover mids and highs whereas tenor and baritone sax cover the lows and low mids.

audioguru said:
An amplifier with distortion has a difficult time trying to sort out the frequencies and makes millions of harmonics that cause FUZZ.
A modern low distortion amplifier has no harmonics that are caused by distortion and has a wide bandwidth to produce the harmonics of the music. The high frequencies of the music "sizzle".

It's all in how you voice the overdrive and what frequencies receive more clipping than others. This is something that non-musicians could ever understand.

In regards to Celestions and their "horrible frequency response"...that is the sound of rock. "Horrible" is subjective...it's an opinion. It may very well be horrible for the music you listen to, but for rock they are the speaker to go with. Again...different strokes for different folks. ;)
 
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In regards to Celestions and their "horrible frequency response"...that is the sound of rock. "Horrible" is subjective...it's an opinion. It may very well be horrible for the music you listen to, but for rock they are the speaker to go with. Again...different strokes for different folks. ;)
Correct.
Horrible sound is horrible. But severely distorted "rock sound" is worse.
 
Correct.
Horrible sound is horrible. But severely distorted "rock sound" is worse.

And again that is your opinion. I'm sure there are many others that would beg to differ. "Horrible" is a human derived thing. It cannot be proven...it is a matter of opinion. Just because you think something is horrible does not constitute it as fact that it's horrible. ;)
 
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