Ok. This aught to be a good one...

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Ok. This aught to be a good one...

Postby ssrythm » Mon Feb 04, 2008 8:03 pm

Please try to explain to me, as if I were a child, how amplification works in regard to pre-amp, amp, etc. I've been reading about jerry amps and reading everyones responses, and I have realized that I am absolutely clueless about amplification. I play Bobby through a Boogie DC50 using an AD200 and a UE400, and I really don't know why other than Bob used the FX units and I liked the way the Boogie sounded for a small, easy to tote amp. I'm always just turnin knobs and f'n around with everything trying to get tone that sounds good to me, yet by the time I get there, I think I'm just setteling cause I'm tired of f'n with it. I think its cause I don't understand why something is doing what its doing, and before screwing with effects of any kind, I need to understand how to get the most and various tones out of the amp. So, WTF? What is the preamp? How does it relate to the amp section? Why would you run a seperate amp like a macintosh? Someone please break it down in idiot terms from a-b-c...z; using Bob's rig as a reference whilst breaking this down for me would be a huge, appreciated, bonus. Thanks in advance, E
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Postby strumminsix » Mon Feb 04, 2008 8:29 pm

Here is the basics:
Guitar input > first gain stage of the preamp tube >
tonestack which basically cuts your signal >
secondary gain stages from subsequent preamp tubes >
an FX loop if your amp has it >
Reverb & tremolo if your amp has it >
-------end of preamp---------
phase inverter (first part of poweramp but a preamptube) >
poweramp tubes > output transformer > speaker

The Mesa tonestack is slightly diff than Fende or vox whereby it cascades meaning the higher you have the bass cranked the less impact the mids and high knobs will have, etc... and so on down the line.

UE400 Ibanez multiFX unit which allows you to run FX in any order with a loop which is assignable in a spot. This allows you to run some FX before the preamp and some after the preamp. Or you can run a tuner first and run everything before the preamp like Jerry did.

AD200 Delay unit. Last piece of your chain.

I'm not sure I understand the question though so I hope this helps.

Basically it sounds like you are confused with all the cool gear you've got.

Are you looking for gear101 or help setting up your rig?

As far as order here is what I'd do assuming you don't have a loop:
Guitar > tuner > wah > UE400 for the FX in the order on the box > AD200 > amp input
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Postby ssrythm » Wed Feb 06, 2008 11:47 am

SS, you helped me get my configuration straight last year, and the rig sounds good. I can't even figure out how to ask the question I'm so equipment illeterate. Ok, what is a pre amp and how does it differ from the power amp. Obviously a pre amp is amplification before something, but what? Why? Is there an amplification 101 site or book that you can lead me to?
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Postby strumminsix » Wed Feb 06, 2008 12:20 pm

ssrythm wrote:SS, you helped me get my configuration straight last year, and the rig sounds good. I can't even figure out how to ask the question I'm so equipment illeterate. Ok, what is a pre amp and how does it differ from the power amp. Obviously a pre amp is amplification before something, but what? Why? Is there an amplification 101 site or book that you can lead me to?


Glad to help. This might help.... Over simplified:
A preamp shapes the signal
A powermap boosts the signal for speakers

The preamp does boost but only because it the signal is being cut too and that it has to hit the poweramp at a certain level which is higher than instrument.

Here is still simplified but more techy:
Guitar input > preamp's first gain stage (pre tube) >
Treble knob (which actually cuts) >
Middle knob (which actually cuts) >
Bass knob (which actually cuts) >
second gain stage (pre tube)>
loops or reverb or tremolo (pre tube)>
----end of preamp---- start of poweramp ------
> Phase inverter (pre tube - splits the signal to the tubes) >
poweramp tubes boosts the signal>
output transformer sends to speakers
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Postby waldo041 » Wed Feb 06, 2008 12:50 pm

Pre Amp = Before Amplification

pre amp - can either be tube or transitor based

amplifier - can be either tube or transitor based.

a combo amp has both a preamplifier and an amplifer.

a hybrid combo is either a transitor preamp and tube amp. or tube preamp and transitor amplifier ala jerry garcia.

transitor based is often called solid state and it's tone is often limited to it's circuit design.

tube based tone can be shaped by the circuit AND the tubes. tubes will sound different from brand to brand and tube to tube.

also speaker play a big part because they project both and is ultimately the end product that everyone hears. there tone is also different brand to brand and moodel to model.


HTH.

peace,
waldo
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Postby Mick » Fri Feb 08, 2008 7:46 am

I saw this question and thought "there must be something on the net with an easy to understand explanation, but within 5 minutes of looking, I didn't find anything that I thought gave the basics in plain english. I am not an amplification expert either, but I will add a few things that Waldo and SS didn't mention that it took me a while to figure out, real basic stuff so feel free to ignore if you are already down the road.

Difference between gain and volume: in an amplification device, the gain is the signal strength going into the device, the volume is the signal strength going out. This will be important in a minute.

"Shape" of the signal: If you had a "perfect guitar" and plucked a string, the resultant signal would essentially be a sin wave. Nice and smooth and round, up and down with frequency of say 440 cycles per second (the A most people tune to). This signal would sound like an A, but would be very dull sounding and not very pleasing to the ear. The easiest shape to understand is the "distorted" shape, or "crunch". This would be a signal that instead of being nice and rounded, it would be more square in the tops and bottoms, almost looking like this (on its side I guess):

[
]
[
]
[
]
[
]
[
]

As opposed to this:

(
)
(
)
(
)
(
)


Both still being at 440 cycles per second, so either way you have the A frequency, but the two signals have markedly different tones. The rounded one looks more or less like what you would get from your "clean channel", the squarish one is more like what you would or could get from an "SCG" channel.

Anyway, there are many ways to get that distorted or crunchy sound. Back in the 50s and maybe 60s, what people would do is load up their amplifier with so much gain, that it couldn't output all of the signal as volume due to the limits of the device. What would happen then, is that the tops and bottoms of the wave would get chopped off, often called "clipping". This works great, but the downside is that it only works at extremely high volumes on your amplifier, and if you live in an apartment, this might make you somewhat unpopular with your neighbors. Another way to get that sound is to "shape" the wave with a pre-amplifier. How that works is the circuit in the pre-amp is desiged and/or set to have a low volume capacity, so you run higher gain into it, the pre-amp clips the signal because it doesn't have the volume capacity to transmit the entire signal, then that clipped signal goes to your main amplification circuit and viola: you have a clipped (distorted) signal at volume levels that are more tolerable for the average living room.

The SCG channel is another way to get the same effect and many others. Well, kinda the same way, it is a pre-amplifier of sorts, just in the same box as your main amplification ciruit, but it can be a seperate device too, just most guitar amps nowadays have one built in. SCG stands for Synchronous Cascading Gain. I doubt I remember enough of my basic electronics courses from college to do even a passable job explaining the math, but the concept is that the device generates harmonic waves to the input signal and selectively adds them (based on your knob settings) to the output signal such that they cancel out or exaggerate parts of the signal to change its tone.

I hope some of this helps.

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Postby I'm on the Bozo Bus » Fri Feb 08, 2008 8:39 am

Good job Mick....
You did what I fiond difficult to do. I am self-taught and if you asked me to play a Dmsus7(add your own suffex to this example) I wouldn't have a clue as to what to play, however if I saw it, or perhaps even heard it, I would say... "Doh.. oh that chord!".

I "Hear" how my amp works and I know what the effects will do in a certain order, I know what my amps will do depending on those effects, my playing style, etc... however explaining why it changes or sounds different is a mystery.
You dumbed it down perfectly,
Thanks and
PEACE,
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Postby Mick » Fri Feb 08, 2008 9:01 am

"Dumbed it down"? Actually, that is near the limits of my understanding. You posted some stuff to me a few days ago about shaping the signal that I still haven't gotten to think about sufficiently to really understand it. I have only been playing for about 1 1/2 years, so I really haven't spent much time fussing over tone all that much. D minor suspended seventh? Well, I know what a D minor would be, I would have to look in a book to figure out what to do to make the suspended 7th version, so you are way ahead of me on both counts!

I started playing when an old guitar and amplifier got dumped at my house, I think because my wife's family has trouble telling the difference between our house and a garbage dump, not that I blame them. When I first started screwing with the guitar, I thought the amp was broken as I had the hardest time getting it to make any kind of sound that I liked (not knowing how to play guitar made that all that much more challenging). After a while, I realized that the amp wasn't broken, I just didn't know how to use it. Once I got the basics above figured out, a few basic tones I like are easy, like a mostly-clean little reverb tone or a crunchy metal-like tone depending on the music and the mood. I haven't gone down the road of effects loops and the likes as of yet.

Anyway, thanks for the kind words!

Mick
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Postby cunamara » Fri Feb 08, 2008 6:26 pm

A D minor sus 7 doesn't exist, so don't worry about it. In a sus chord, the 4th tone replaces the 3rd (you figure this out by counting up from the root of the chord- D E F G A B C D):

D minor: D F A

D major: D F# A

D sus: D G A

In the open position, the chords are voiced:

D minor: D A D F

D major: D A D F#

D sus: D A D G

In both cases, you can see that the sus chord has no 3rd and thus is neither major nor minor.

The 7th of any D chord is C which would replace the second D note (the one on the 2nd string). It could be added to any of these chords.

Of course, this doesn't help at all in the discussion of amplification and I am sorry for the topic drift. To get back to the topic at hand, as others have said, basically your guitar puts out a weak signal. This goes into the preamp which boosts the signal a bit and also includes the adjustments for treble/mid/bass. From the preamp the signal may go through an effects loop (none of my amps are new enough for this, so they all go between the guitar and the preamp) and in any case goes to the power amp, which is what drives the speakers.
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Postby ssrythm » Fri Feb 08, 2008 10:06 pm

Thanks Mick! ...and SS But that is exactly what I'm talking about! I can understand that somewhat!
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Postby chinacat503 » Fri Feb 08, 2008 11:06 pm

actually a chord can be sus2 or sus4 - when the third note of the scale is replaced by either the second or fourth note, suspending the chord between major and minor
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Postby shakedown_04092 » Sat Feb 09, 2008 7:55 am

chinacat503 wrote:actually a chord can be sus2 or sus4 - when the third note of the scale is replaced by either the second or fourth note, suspending the chord between major and minor


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Postby shakedown_04092 » Sat Feb 09, 2008 7:56 am

cunamara wrote:The 7th of any D chord is C which would replace the second D note (the one on the 2nd string). It could be added to any of these chords.


:?: Don't you mean C#?
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Postby bucketorain » Sat Feb 09, 2008 8:42 am

I have a question, i have a Fender Blues Deluxe, would this have a built in Pre-Amp, i'm really not sure....? If not, would there be any reason to get a rack mount pre-amp for it?
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Postby strumminsix » Sat Feb 09, 2008 11:58 am

ssrythm wrote:Thanks Mick! ...and SS But that is exactly what I'm talking about! I can understand that somewhat!


Awesome!

bucketorain wrote:I have a question, i have a Fender Blues Deluxe, would this have a built in Pre-Amp, i'm really not sure....? If not, would there be any reason to get a rack mount pre-amp for it?


Yes. All combos have pre-amps unless they specifically state they are a poweramp combo.
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