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please explain gain settings???

post #1 of 16
10/12/05 at 3:01am
Thread Starter 
i dont understand what all the gain settings means, i know high gain settings are suited for higher impedance cans and low gain for low impedance. Amps like the go-vibe and zero audiocraft from ebay asks for the gain settings before order, and some amps have a gain switch. So what happens if i plug a low impedance can into an amp w/ a high gain setting or vise versa? Is there a performance difference if the gain settings of the amp doesn't match the headphone impedance? Would it affect the SQ at all?

What if i have 2 headphones w/ different impedance specs, would i need 2 different amps w/ matching gain setting?
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post #2 of 16
10/12/05 at 3:20am
Gain is basically the amplification multiplier. Say your feed 1V into an amp that has gain 11, you'd get 11V output

High imp cans are more voltage dependant than low imp cans, therefore having a high gain is beneficial. Another thing with high gain + low imp cans is that, you get very small control over the volume since turning the pot up a little might increase the volume by a great deal.

Powering a high imp can with a low gain amp would require you to turn the volume way up to get decent listening level. generally, a mid gain setting is ideal if the amp is not specifically designed to drive certain phone.
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post #3 of 16
10/12/05 at 6:33am
Thanks for your informative post kin0kin, I was wondering the same thing. So, how do you know what level of gain you need for your particular headphones? What is considered medium or high gain?
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post #4 of 16
10/12/05 at 8:14am
Dr Xin, who I tend to belleve says 'The amplification gain switch is mainly for very low-efficient headphones such as AKG 501 and for people suffering from hearing loss.'

Low-efficent is probably tied in with high impedance, but also I'm tempted to think Open 'phones are probably less-efficent than 'closed' ones.
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post #5 of 16
10/12/05 at 9:53am
Thank you kinokin for your explaination. Helpful.
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post #6 of 16
10/12/05 at 10:12am
BTW-a couple of "gain rules" :


1-if you are always at the very bottom of the volume control rotation when you listen to music your amp has too much gain.Dual volume control left/right tracking balance is the worst at the very beginning of the rotation plus most of the resistive element is directly in the signal path which being a high resistance has more noise than if this resistance were lower

2-conversely if you always have your volume control at or near maximum you do not have enough gain.Can be a monor annoyance or if you run out of rotation and still feel you need more volume for a good level,a real problem.
That or you are already deaf and it does not matter

tossing out numbers is one thing but actual use and the human/machine interface also important if only to lessen the aggravation factor
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post #7 of 16
10/12/05 at 10:36am
Quote:
Originally Posted by rickcr42
2-conversely if you always have your volume control at or near maximum you do not have enough gain.Can be a monor annoyance or if you run out of rotation and still feel you need more volume for a good level,a real problem.
That or you are already deaf and it does not matter
Actually on Xins site he says its more acceptable if you can reach a volume level thats satisfactory without using the gain switch, even if the knob is turned fully on.

I believe this is to save power. Max Volume without extra gain is obviously consuming less power than extra gain at a low volume. Plus gain itself might require extra power just in activation?
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post #8 of 16
10/12/05 at 12:56pm
Quote:
Actually on Xins site he says its more acceptable if you can reach a volume level thats satisfactory without using the gain switch, even if the knob is turned fully on.

I believe this is to save power. Max Volume without extra gain is obviously consuming less power than extra gain at a low volume. Plus gain itself might require extra power just in activation?
You are missing my point entirely.You will not have the same gain requirements for two very dissimiliar headphones so if you have a headphone amp that has a gain of X10 and try to use it with very sensitive headphones you will not be able to move the volume control at all without it going from barely heard to too loud with very little rotation.
This is known as a "twitchy" volume control and a sure sign of too much gain.

The other extrmeme is the too low gain where you must have the volume full wide open and even then you do not have enough real volume.This usually happens when you combine low output sources with low efficiency headphones combined with low gains.
The normal gain for my "Grado" amps is X2-X3 which will not drive an inefficient headphone to a good listening level unless the source already has a large voltage output.Portables do not so just not enough gain available for good volume.

Neither condition has anything at all to do with battery life or power consumption and everything to do with proper drive power with the system/headphones the amp is used with.System matchups are way more important than the individual parts
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post #9 of 16
10/12/05 at 1:14pm
You're talking about different headphones and I'm not. I'm just on about the amp. Its blatently obvious different headphones have different driving needs.

Its also blatently obvious the higher volume you have means you're using more power. You don't get more volume for free.

Battery life is nothing to do with any 'conditions', its a varying rate.





We're both right in what we say. We're saying different things. I'm a licensed Electrical Engineer btw...
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post #10 of 16
10/12/05 at 2:06pm
dude,did you even bother reading the thread topic ?

Quote:
please explain gain settings???
more to it than just X10 or X1 if you don't know what context to put those figures in.your post really has no relevance man.

Quote:
We're both right in what we say. We're saying different things. I'm a licensed Electrical Engineer btw...
I am a nail banger BTW but still know audio electronics just a bit
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post #11 of 16
10/12/05 at 2:47pm
Arse arse arse! I typed a long reply and it disappeared.

My main point was that I took two points from Dr Xins site on gain of the SM3. Nothing to disagree with you. Just agreeing you're right is not much help.

The Engineer comment was to show I'm not speaking out of my butt.
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post #12 of 16
10/12/05 at 2:53pm
Quote:
The Engineer comment was to show I'm not speaking out of my butt.
Nail banger comment to show I may be

cheers man
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post #13 of 16
10/12/05 at 3:01pm
(y)

No worries man....I'm not Australian! :P
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post #14 of 16
10/12/05 at 3:14pm
Quote:
Originally Posted by Alereon
Thanks for your informative post kin0kin, I was wondering the same thing. So, how do you know what level of gain you need for your particular headphones? What is considered medium or high gain?
looking at only impedance and disregarding sensitivity. I'd say gain of 6 is mid, and gain of 11 is high. That's usually what I use for my diy amps.

For low imp phones like more earphones, and IEMs, a gain of 2 is already more than enough to drive them to ear bleeding level. But the opamp's characteristics have to be taken into consideration when setting the gain. For example, you could set a gain of 2 for unity gain stable opamps like the opa627, but you would want to have around gain of 5 or more for opa637 in order for it to work with better stability. Additionally, the voltage gain isn't all that important for low imp cans, they are more current dependent.

You'd want around gain 11 or more for high imp cans, especially those that are really inefficient. otherwise, you might not be able to get adequate volume out of it. ( what's the point of an amplifier when it can't deliver enough juice to drive the phone right? )

Like mentioned earlier, you'd wanna set the gain at around 5-6 for a general purpose amp, it's pretty much the sweetspot - better stability, adequate amplification for most phones, doesn't suck up as much power. Anyway, if you want to go a little fancier, adding a dpdt switch along with 2 more resistors would allow you to switch the gain to accomodate more phones
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post #15 of 16
10/12/05 at 3:58pm
Now with all that said: how does the potentiometer play into this?

At a given gain (lets say 10) and using a 50k pot, I listen at the 10-12 o'
clock position (about 40-50%). If you go with a 20k or 10k pot, does this mean you would not be able to lower the volume as much, or perhaps be to loud even turned all the way down?
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