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

[Sea Chief]

The OP doesn't seem to have a clue how things work.

Please answer these questions.

1) The pickups in a guitar convert the wiggling of the strings into an electrical signal. If you just connect a cable from your guitar to a speaker cabinet, why doesn't it make any noise ?

2) In a guitar amplifier, the Input jack is connected to a couple of resistors, then it is connected to a tube. Why is it done this way ? What does the tube do t the signal ?

I don't care to reply to mildly angry sarcasm dressed as helpful questions, thanks.

SC

[loudthud]

The OP doesn't seem to have a clue how things work.

Please answer these questions.

1) The pickups in a guitar convert the wiggling of the strings into an electrical signal. If you just connect a cable from your guitar to a speaker cabinet, why doesn't it make any noise ?

2) In a guitar amplifier, the Input jack is connected to a couple of resistors, then it is connected to a tube. Why is it done this way ? What does the tube do t the signal ?

[Sea Chief]

The above is just one example. Different pre amps have different clipped waveform characteristics. But always different from the power amp and almost never symmetrical like power tube clipping.

Hi Chuck, I'm still not able to grasp the preamp to power amp though. Irrespective of any distortion characteristics of different settings.

So in effect since HH's stating that my amp only has a Volume control in the preamp, I've gone back a step. I'm back to re-evaluating how an amp works.

So my innitial asking about introducing an MV.. is far in advance of where my understanding is now. That is IF my thinking of there being a similarity between my hifi two-box setup, & a guitar amp, has validity: I don't know whether using this as a reference is a valid learning 'tool'.

That said, your diagram chimes with using an amp with two knobs one Vol & another MV: I only recently had my Music Man 4-10, so remember the results from the two knobs interacting, even if I didn't know how an amp works (realising this only just now).

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).

But again thanks for trying to help- I'm unfortunately off on an unintentional trajectory though presently, trying to get the idea of a single Volume knob residing in the preamp, not as I had resolutely had it placed in my head for 35 years, that being at 'the end of the path' in the (end) of the power amp, before the spkrs.

Thanks, SC

[Chuck H]

The above is just one example. Different pre amps have different clipped waveform characteristics. But always different from the power amp and almost never symmetrical like power tube clipping.

[Chuck H]

Ok... Let us try another graphic.

[Sea Chief]

This isn't to say I've got it now, at all though. I'm for the first time ever, looking at my (two boxes) hifi amps wondering what the heck is actually going on!

A path you see, in the literal sense has a beginning & end, a line. It seems in the case of an amp, the path goes forward.. from preamp to power amp (the boxes digram DOES show this path L to R after all).. then instead of "exiting" in a linear way RHS, it instead sort of doubles-back into the preamp.

This is now how my head is having to consider things. And tbh it's not possible for me at this juncture, to visualise it, or make logical sense of this U-turn (& likely totally wrong way of considering it anyway). I wonder if anyone can put themselves in my shoes here. How, I'm thinking of things wrongly.

Thanks, SC

[Sea Chief]

A preamp volume controls the signal volume (or level) to all following amp stages including the power amp.
Should be obvious, no?
All non-master volume amps only have preamp volume.

Hi HH.

Ok this is obviously the crux of why I haven't been able to grasp things so far. When there's this 'signal path' I visualise a beginning/in & end/out: beginning being guitar in, then along a chain of preamp xyz, then to the power amp stage, then ultimately OUT after this. Left to right.

The two box diagram suggests this 'lineage/ linkage' too, so had just always assumed the 2nd box Vol.. is always there (& may be called Vol if there's one, or MV if there's ALSO one added into the preamp) .. & the added preamp Vol can be introduced (as MV) in either Vol guise, or Gain guise. That is what I had learnt from the thread. But with huge complications, because this doesn't seem to be right all along.

Last night I then quizzically look at my hifi preamp & poweramp. And it clicks that the Vol knob os on the preamp & not the poweramp: I had thought you see there was no correlation between a SS hifi amp, & Tube guitar amp. So it seems there has been all along.

Ok I've now got to re-evaluate & consider this single Vol on the preamp, & split it from the power amp, in my head. At the moment.. because the above was locked into how I perceived things.. it isn't registering. I can't visualise it. It still seems illogical.

Thanks, SC

[g1]

Yes they did maybe not you. And Gain stages, have been repeatedly said to be in the preamp section g1.

Don't tell me, now you're suggesting they reside in the power section..?

SC

No, you yourself said it in post #55, now you claim someone else said it.
Stop mis-representing what people said, use direct quotes.

[Dave H]

Sorry, but this is new info for me. I cannot imagine how an amp cannot have a power amp volume control, but only a preamp one.

Why not? The volume control could be located at any point along the signal path.

[Helmholtz]

I cannot imagine how an amp cannot have a power amp volume control, but only a preamp one.

A preamp volume controls the signal volume (or level) to all following amp stages including the power amp.
Should be obvious, no?
All non-master volume amps only have preamp volume.

[Sea Chief]

Can you not just twiddle with the knows to determine what you like?
do you need to understand it to use it or can you use it and then understand it? I am the latter always have been just fiddle till it sounds right.
Nosaj

I'm just trying to understand it, but yes I could just twiddle knobs, but this has been decades of not understanding the interaction between a Vol & a MV, always wondering what the difference is, why there are two, why sometimes one seems to be called a Gain knob.

I never knew it would be so hard to get the basics of though. The frustrating thing is everyone else seems to find it incredibly simple. The very idea seemingly just landed on me at this late stage, that a non-master Vol amp only has a preamp vol.. has utterly fried my head. I think I have to give up now.

Thanks, SC

[Sea Chief]

No one said this, stop mis-quoting what people said. And reference the posts you are referring to.

Yes they did maybe not you. And Gain stages, have been repeatedly said to be in the preamp section g1.

Don't tell me, now you're suggesting they reside in the power section..?

SC

[Sea Chief]

Exactly!



No, as that would be a Master Volume, which an AC30 doesn't have.

Just read my posts. I'm fed up of repeating myself over and over.

Sorry, but this is new info for me. I cannot imagine how an amp cannot have a power amp volume control, but only a preamp one. This doesn't make any logical sense to me. I always thought if an amp had only one Vol, then it has to be the main power section IE where all the preamp & prior stages are ultimately fed into.

Surely you can see why I think this is simply logical. And so you surprised me saying my amp has only preamp volume. I find this a really strange concept (& tbh I cannot get my head around it), & have never even considered it before your post.

If you are repeating yourself it's only because I haven't understood it. Obviously.

SC

[g1]

One person says my Gain knob on my Randall should be considered like a MV. Next I'm told Gain things are preamp based.

No one said this, stop mis-quoting what people said. And reference the posts you are referring to.

[nosaj]

Can you not just twiddle with the knows to determine what you like?
do you need to understand it to use it or can you use it and then understand it? I am the latter always have been just fiddle till it sounds right.
Nosaj