Vox AC30/ 6 (TBX). Add an MV ?

[nosaj]

I think this thread has run it's course. Seachief if you have questions we can recommend some books for you to read.
nosaj

[Greg Robinson]

Input gain stages

What the hell do you think the tubes ARE?

signal chains

How the signal flows through the amp. Much like water through a pipe.

then the multiplying by 10 (why 10??)

What do you think amplifiers DO? You do realise they take a signal and amplify it right? 10 was an arbitrary choice, as you have already been told. Each gain stage will amplify by some amount, dependant on the design of the circuit. I chose 10 for my example because it's an easy number.

the whole guitar volume thing mystery (100mV if strings hit hard,

Again, an arbitrary, but not unrealistic number. A guitar will put out some volume. The volume can be represented as a voltage. I chose, for the example, that number to be 100mV.

but a far higher 2v if they're not seemingly being hit at all).

You MUST be taking the piss right? Not once in my diagrams was 2V mentioned. AND btw smartarse, if the strings are not being hit then the level is 0V.

I'm only trying to understand why a vol is on the preamp,

Well we've all done our best to try and explain that to you, but as it turns out, we tried to teach you multiplication tables before you understood the basics of addition like 1+1=2.

what a gain knob is relative to a vol knob.

Gain and volume are different names for the same control. Typically on a non master volume amp, this control is called volume. Often (but not always) on a master volume amp this is relabeled gain for clarity - to avoid having two controls both labelled volume.

[Sea Chief]

Try answering him with short coherent sentences for the Love of Jeebus. All this blabbering is not helpful.

edit: part of your post that I deleted was the majority of the post. Really only two sentences stand out as a good answer.

Ok 2nd post, apologies I missed that yourself wrote the one earlier (which contained 'noise floor': Gonz I've never in my life heard of this term- so I mean how can this 'noise floor' unknown, do anything other than further confuse me?

This is what I'm trying to explain: I appreciate the explanations & replies, but feel -overwhelmed- with a sudden shedload of unknowns like sag, headroom, (squared off) waves, oscilloscopes, terms like noise floor, voltage dividers, Input gain stages, signal chains; then the multiplying by 10 (why 10??), the whole guitar volume thing mystery (100mV if strings hit hard, but a far higher 2v if they're not seemingly being hit at all).. all pretty much in one go.

I'm only trying to understand why a vol is on the preamp, instead of fundamentally on the power amp (before it exits to the spkrs), & what a gain knob is relative to a vol knob. And lastly what an MV is. IE my Gain knob (Randall RD5) sounds like a super-saturated distortion -effect- affair, bearing zero resemblence to my Vol knob on my Ac30 or my Twin Reverb: why is this?

Thanks, SC

[DrGonz78]

Hi Greg,

Yes, I turn the knob on my hifi & the volume goes up. Or..
Yes, I turn the knob on my guitar valve amp, & the volume goes goes up.

SC

Try answering him with short coherent sentences for the Love of Jeebus. All this blabbering is not helpful.

edit: part of your post that I deleted was the majority of the post. Really only two sentences stand out as a good answer.

[loudthud]

As to how the MV -only- affects the power amp section in your diagram.. this is WAY in advance of where my understanding is. I haven't on god's earth got a clue as to why or how an MV can affect just the power amp, if it's placed before it (& if that's where your diagram suggests it is placed).

You don't seem to understand signal flow. Do you expect the signal to go backwards through the Master Volume and affect the Preamp ? Do you know what a Voltage Divider is ?

Are you refusing to answer the questions because you don't know the answers ?

Are you one of these AI Robots that just posts stuff to get a reaction from people.

A voltage divider? No, I have never heard of these two words in conjunction with each other.

It has been suggested that Sea Chief has some pathological need to be helped and paid attention to. He pretends not to understand so he can get more attention. This makes him feel whole somehow and the more someone tries to explain something to him, the more he doesn't understand.

Sea Chief, please seek help from medical professionals in your location.

[Sea Chief]

Apologies, I'm doing my best to contain my exasperation.

Seachief, do you understand how a potentiometer functions as a volume control? Do you understand that it is a voltage divider? That the guitar signal is a (varying/AC) voltage?
Ignore everything else for now. Can you just answer those three questions please.

Again, I have never heard of "the guitar signal is a (varying/AC) voltage".

I was asking about Master Volume, so guitar signal hasn't been in discussion, until you mentioned it. I wasn't expecting guitar signal to be relevant to the volume controls on my amp whatsoever tbh. Guitar signal seems, to be alot of what you're talking of, within explanations I'm hugely confused about: meaning I am -more- confused with it's inclusion wondering why this is suddenly being talked about.

Furthermore "varying/ AC voltage" has never been mentioned on the thread either. Certainly not with "guitar signal is a.." preceeding it.

Thanks, SC

[Sea Chief]

Apologies, I'm doing my best to contain my exasperation.

Seachief, do you understand how a potentiometer functions as a volume control? Do you understand that it is a voltage divider? That the guitar signal is a (varying/AC) voltage?
Ignore everything else for now. Can you just answer those three questions please.

A voltage divider? No, I have never heard of these two words in conjunction with each other.

Surely, if this is a fundamental component of understanding any of this, then I might have been told this-? Especially if i say that I'm right back at step 1, trying to understand *how a Volume on a preamp affects the power amp (& why it's located here & not just before the 'exit' to the speakers). I have stated this is where I'm at, countless times now. I just cannot be expected to understand any of the diagrams, see any relevance to any of them, certainly not a step onward & being capable of -comparing- one to another... IF... I say as clearly as I possibly possibly can, that I'm right back *here at step 1. Can I?

Thanks, SC

[Sea Chief]

So you’re essentially complaining about the fact that you are receiving too much help? I give up.

But you haven't helped gonzo!! That's your FIRST post on the thread!!

Strewth alive.

SC

[Sea Chief]

Ok, back to the very most basic thing.
DO YOU UNDERSTAND HOW A VOLUME CONTROL WORKS?
That was the whole thing I was trying to show you with my diagrams.
If you don't, this whole discussion has been rather pointless.

Hi Greg,

how to answer this? How do you mean? I'm tempted to answer thus..

Yes, I turn the knob on my hifi & the volume goes up. Or..
Yes, I turn the knob on my guitar valve amp, & the volume goes goes up.

Or am I to ask you: which volume are you referring to, the one on my guitar, or the the one on my amp?
Or am I to ask you: what amp Vol control are you referring to- the Gain knob, the Volume knob, or the Master Volume knob-?

If I asked this to my friend, who bizarrely has no interest in amps despite being in a band for decades & collecting electrics including a rickenbacker 360.. he'd say "how do you mean? Yes I twiddle this knob near the strings, or there's a Vol knob on my amplifier".

I'm the same, IE How do you mean-? Can you rephrase your question maybe?

SC

[Greg Robinson]

Apologies, I'm doing my best to contain my exasperation.

Seachief, do you understand how a potentiometer functions as a volume control? Do you understand that it is a voltage divider? That the guitar signal is a (varying/AC) voltage?
Ignore everything else for now. Can you just answer those three questions please.

[DrGonz78]

So you’re essentially complaining about the fact that you are receiving too much help? I give up.

[Sea Chief]

.. INPUT signal it can handle is 1.5V because 1.5x10=15V. So if you were to feed 2V into that stage..

Hi Greg, ok 99% of your recent big post (which has this ^ section in it) I can't understand. Apologies again.

But I am sensing that perhaps you are attempting to explain the interaction with an amp vol (I'm guessing at vol 10, although av=10 is still not clear to me, because you explain this 10 figure in other ways besides amp volume 10 in this big post above).. & guitar vol.

Now, this section I've highlighted above, can you tell me: when you say "feed 2v into" are you here talking about the -guitar volume knob-?? "Feeding" hasn't been used before, so I have to consider what is feeding. To then get a picture of what your trying to put forward as an example here.

You put a figure of 100mV on the diagram, which when I asked what this arbitray (to me) figure was, someone answered that "it is the voltage of hitting the strings". But the figure of 1.5v, or 2v as mentioned above, are so far in excess of 100mv, that I cannot rationally equate it to having any connection to both your 1.5v, & 2v "input" figures above. So these two figures.... to me are a mystery not only as to their numerical figures, but also as to what they represent.

Thanks, SC

[Greg Robinson]

Ok, back to the very most basic thing.
DO YOU UNDERSTAND HOW A VOLUME CONTROL WORKS?
That was the whole thing I was trying to show you with my diagrams.
If you don't, this whole discussion has been rather pointless.

[Sea Chief]

Do you mean diagram A and diagram B?

Or are you referring to the different boxes (that represent amplification stages) within diagram A?

Hi pdf, no I cannot compare diagram A to diagram B, because I cannot get past 1/3rd of the way into diagram A. I am effectively stuck part-way along diagram A.

I'm stuck specifically at: a white box, with Input Gain Stage as the first 3 words. This 15v is completely meaningless to me (& that's after two people have tried explaining it). You see 'headroom' is a concept about 2 light years ahead, if I'm still trying to figure how a preamp contains the volume control. On my amp. Both my amps in fact. I'm still stuck back here. At this ridiculously early point. HH landed this on me, last week- & I'm currently trying to get to grips with it.

So I can't possibly consider boxes containing 'headroom 15v', "noise-floors" (wtf?), oscilloscopes (I have no idea what these do), &, if I'm stuck so early on with diagram A which contains entirely new & mostly meaningless aspects to me, how I'm meant to 'compare' one diagram to another. Let alone then consider adding MV into the mix, or do sums to determine something.

I've said where I am in terms of understanding, & asked if the distortion aspect can just be sidelined for now. But with respect for the efforts, I'm then deluged not only with the whole gamut of distortion facets, but ontop, entirely new terms hitherto not once mentioned on the whole thread (headroom for eg).

I do have an extremely vague notion, that Greg is talking about the interaction between the guitar volume control, & the amp volume control. But this is light years ahead of where I've said I am. Also, I've never, once actually been in a situation wherby I can turn an amp to 10 & dial down the guitar volume, & consider headroom characteristics from simply experiencing it. Whenever I do turn an amp up towards 5-6, then dial a guitar volume down, the treble evaporates, so I have no choice but immediately dial it up again: I have asked why this is, & shown how to add a cap or something, but it's made no difference: the treble dissapears whenever I turn down the guitar vol. So in effect, I will never need to know this guitar vol + amp vol interaction, because (for another infathomable reason) the two simply do not work if the treble goes awol. Whatever the 'cleanliness' of the sound.

I think maybe Greg is possibly assuming that I can dial an amp to 10, then have a useable guitar situation whereby I can dial it down & hear different things: then possibly use a diagram to consider what is actually happening. But again, this is all to do with distortion aspects it seems. I'm still WAY BACK on the volume control placement !!

Thanks, SC

[DrGonz78]

I just think of it as there is a noise floor. This is the non-audible level, silence and hum. So the floor represents 0 volts and that is with no signal applied. Headroom is what you have before it reaches clipping. (Did we say 15v is the max power?)Think of it as a limiter if you record or listen to music. It’s a form of compression that occurs when you run out of headroom. The truest sense of what is distortion occurs when this happens. So if have 30 volts of power supplied then I have 30 volts before clipping. Say it just that simple and think about it before thinking about it.