Assume you have a volume control with a couple fixed positions. From the fully-turned-up position (no attenuation) to the next lower position it might only be a 1 dB difference, but from the 3rd to last to the 2nd to last position the difference could be 10 dB.
So you turn up from silence: wow, huge volume increase with each step. But these get smaller and smaller...

Quote

An amp whose volume control progresses to a low attenuation state with very little rotation of its knob can make the amp seem more powerful. This is one of the oldest tricks in the book going back to the beginnings of mass market radio in the 1920s and 1930s.

Perhaps I'm misunderstanding what you mean by attenuation in the above context. Based on what you're saying there is more signal with less rotation of the knob, but it sounds like the opposite. Apologies if I misunderstood your meaning.

But if the volume knobs of amps are different, and the gain, that also means that different preamps can sound different just because of the implementation of the volume controls and the gain of the preamp? Correct?

So if someone does claim adding a preamp made an audible change, then it isn't really so far-fetched given the variables above. But not because of any inherent secret sauce, but more because of changes in loudness from preamp to preamp.

Quote from: saratoga on 2014-10-17 19:29:39

Quote from: Rich B on 2014-10-17 19:14:56

Why don't you read what I write instead of making assumptions about you think I wrote? It's also getting annoying! You just come crashing in and start stirring the pot. Why can't you stay away from my threads?

Because what you write tends to incomprehensible.  Your statement above about different volumes sounding different . . . are we supposed to assume that you didn't realize that volume control could make something sound more or less loud?

It was said earlier that different volume controls have different attenuation and different amps have different gains. So based on this I assume that comparing preamps at specific volumes will be invalidated based on the these two things.

I'm just trying to understand this. I don't appreciate the badgering.

Quote from: Rich B on 2014-10-17 18:08:10

Quote

An amp whose volume control progresses to a low attenuation state with very little rotation of its knob can make the amp seem more powerful. This is one of the oldest tricks in the book going back to the beginnings of mass market radio in the 1920s and 1930s.

Perhaps I'm misunderstanding what you mean by attenuation in the above context. Based on what you're saying there is more signal with less rotation of the knob, but it sounds like the opposite. Apologies if I misunderstood your meaning.

I'm thinking you've got the idea - there is a greater increase for a given amount of rotation at low volumes then there is at high volumes.

Quote

But if the volume knobs of amps are different, and the gain, that also means that different preamps can sound different just because of the implementation of the volume controls and the gain of the preamp? Correct?

Right, which is why to do a listening test right, you measure the outputs of the UUTs with a voltmeter and match that for the same inputs. You ignore the volume control setting required. 

Now you get why knowledgeable people frown when people start talking about volume control settings - they can and often do mean nothing in terms of actual performance.

Quote

So if someone does claim adding a preamp made an audible change, then it isn't really so far-fetched given the variables above. But not because of any inherent secret sauce, but more because of changes in loudness from preamp to preamp.

Exactly!

Since audiophiles generally don't match levels precisely, their comparisons are pretty much guaranteed to involve audible differneces. But the cause  of the difference has nothing to do with inherent sound quality - its all about their poor level matching.

Add in the long switching delays, and everything is pretty much guaranteed to sound different, even two identical copies of the same make and model of equipment.

So if you have an amp that isn't playing loud, that means it has more current available. The louder you play, the less current you have available until you reach a point where you exceed the available current and the amp clips?

Just out of curiosity, what makes you think that

And are you familiar with Ohm's Law and the relationship between voltage, current and power?

Do you know how a traditional, linear, non-regulated power supply works? Are you familiar with what a capacitor does?

Are you familiar with what a capacitor does?

Quote

Just out of curiosity, what makes you think that

?

Well, Arnyk said that if you reduce SPL by 6 dB that it doubles the effectiveness an amp driving low impedance loads.

Quote

Do you know how a traditional, linear, non-regulated power supply works? Are you familiar with what a capacitor does?

I don't think so, but why are you asking? Are you saying what I said above was wrong?

Arnyk, you mentioned a while ago in the thread that amps that aren't playing that loud can more easily handle low impedance loads.

So if you have an amp that isn't playing loud, that means it has more current available. The louder you play, the less current you have available until you reach a point where you exceed the available current and the amp clips?

If you think about the question, the answer is reasonably obvious. The amp does not have "current available" it has potential, or reserve, that isn't being called upon. Playing at low volume means you're further from the limit. A low impedance load demands more current for any given volta

?

Remember that simply not running an amp at such a high wattage dramatically improves its ability to power low impedance loads.

Reducing the SPL by 6 dB roughly doubles the ability of an amp to drive low impedance loads. IOW an amp that can drive a 6 ohm speaker to a certain peak voltage can drive a 3 ohm speaker to half that voltage. This is important because very few people actually push their equipment anywhere near its maximum capacity, and if they do most only do so very infrequently.

As a rule speakers have highly variable impedance curves so whether the amp actually sees the low impedance segments of the speaker's impedance curve critically depends on the distribution of frequencies versus power in the music

Quote

?

This is what Arnold said in the audible clipping thread :

Thinking of it as "current available" isn't the best way. Can you fill a 40-gallon bathtub from a 50-gallon tank? Yes. Would a 500-gallon tank help? No! If the bathtub were 100 gallons instead, however, the former just won't do.

So basically, if you are clipping, lowering the volume helps. I would not read too much into that...

My understanding is that the current is determined by the impedance of the speaker, but also varies depending on the voltages applied.

My understanding is that the current is determined by the impedance of the speaker, but also varies depending on the voltages applied.

At a lower voltage, less current is required and at a higher voltage, more current will be required.

So by lowering the voltage, you kind of give the amp breathing space and more headroom to handle low impedance dips.

Vaguely.

I don't think so, but why are you asking? Are you saying what I said above was wrong?

There is no "required". You are not "asking" or "demanding" current. If you put more pressure in a water pipe, more water will flow through it per unit of time. You don't "ask" or "demand" more water.

No. The amp doesn't need "breathing space", and the headroom will be constant.

It is totally OK not to have a degree in electronics, but when you don't understand something, your way of communicating that is to question what you have been told. I hope you can understand our frustration with that. Disagreeing is OK if you actually know what you are talking about, and can explain why - but it is a rather ineffective way to deal with not understanding.

Quote

So basically, if you are clipping, lowering the volume helps. I would not read too much into that...

But that's not what he said. He said not running the amp at a high wattage dramatically improves its ability to power low impedance loads. No clipping was mentioned in that post.

Then instead of required, I could use the word "needed"?

That's my way of processing the information. You might not like it, but that's how I do things.

This is worst possible question you could ask. The point of this task is not memorization. Rather, the goal is that you integrate what you are being told into some sort of working model of how things work. Either do that or do not bother.

The assumption here is that you are understanding what is being said in previous posts and applying it to subsequent posts. If you just take each post in isolation, then you are learning nothing, and simply wasting everyone's time (not the least your own).

The way you want to think about this will not work.

So how am I supposed to learn if I'm getting contradictory information?