[milkweg]

Friend of mine read an article that said it just boosts the volume but I thought it was for better impedance matching? I was using the high gain setting on my LunchboxPro because my DT990pro are 250ohm headphones but today I tried the low gain setting and they actually sound smoother on that setting. On high gain there seemed to be a bit of bloat in the bottom end and the highs sounded brighter. What exactly does the amp do internally when you switch between hi and lo?

 

[Jdogg]

X2

 

[kbug]

x3

 

[Sovkiller]

The gain switches usually set different levels of gain, as the name says, in the amplifier, and you can achieve that by different methods, not sure what is used in that particular case, and without getting too much into technical details that I'm not very familiar with...Depending on the headphone to feed you select one or another.

But IMO the gain has more impact on the sensitivity of the headphone than on the impedance as such...for different impedance usually designers use impedance matching circuits/steps/devices or whatever they decided to use, sometimes transformers, other times small resistive networks, etc...

 

[cegras]

I think a definition of gain vs volume, and what each one is, is in order. Anyone up for it?

 

[PhaedrusX]

in simplistic terms, the gain switch basically amplifies the incoming signal from your source, and is usually described as a multiplication of that input signal (2X, 5X, etc.). the higher the gain, the higher the ratio of power (usually measured as voltage) from source to amp, with more volume being the end result. so essentially, your friend is not wrong, and volume control is the biggest reason for having a gain switch on an amp.

 

[kbug]

Quote:

Originally Posted by cegras /img/forum/go_quote.gif I think a definition of gain vs volume, and what each one is, is in order. Anyone up for it?

Good question. I have the same doubt. I notice the sound is louder when you switch from low gain to high gain. How does it compare to increasing the volumn in low gain?

 

[cegras]

I think I may understand it now.

Gain multiplies the input signal, and volume controls the final output signal somewhere along the way.

But volume relies on gain as the "base." This way, for high impedance headphones that need more of a voltage swing, high gain is good because the input signal will have a larger voltage difference between the top and bottom peaks.

Am I on the right track?

 

[MatthewK]

At first I was using the lowest gain setting with my HD650's after receiving the LD MK IV SE in the mail a few months ago. I read somewhere that "lowest gain = best quality" and I don't mind cranking the volume knob up high. I was a little disappointed with the bass quality, so I contacted David at LD.

It only took him two emails to figure out the problem. He suggested I change it to the highest gain for HD650 headphones. There was a huge difference after I changed the gain setting. Bass was absolutely solid and the overall sound quality was raised quite significantly to my ears. HD650's are voltage hungry so that probably has something to do with it. From what I gathered in David's email, gain doesn't equal only an increase in volume like I originally thought.

 

[kbug]

Hmm, interesting...

 

[nikongod]

Quote:

Originally Posted by cegras /img/forum/go_quote.gif I think a definition of gain vs volume, and what each one is, is in order. Anyone up for it?

They dont exactly compare so smoothly.

What we are REALLY concerned with is the voltage (or current, but they are locked together for any 1 given headphone) output of the amp, this will dictate the volume.

The topic of gain pops up, because pretty much every commercial product here has it.

If we were to volume match with a proper sound level meter the same headphone on 2 amps 1 with gain of 2 (for example) and 1 with gain of 10 (again a nice number) and then measure the voltage output of the amp we would see they are (drumroll please!) the same! The position of the volume control may be different, and this causes many people lots of confusion.

On the amp with the gain of 10 the volume control would be around 9'oclock
on the amp with gain of 2 it would be around 12.
Many people (incorectly) correlate the position of the volume control with power, it is simply not the case as seen above: we have verified that both power and sound levels are the same.

Now why this REALLY matters, and gain controls are awesome:
Odds are good that my example of 9'oclock and noon are a little louder than you may listen with these hypothetical amps (I hope so for the sake of your ears unless you have a particularly weak source) so we will now say that with gain of 10 you listen down like 1 hour on a clock face above "off" and with gain of 2 you listen 3 hours higher.

Potentiometers dont "track" perfectly (there is some mismatch), and are especially bad at the lowest volume they can muster. If you have ever heard one side louder than the other at very low volume and then it comes equal as you turn it up you have heard this.
We just saw where the high-gain amp had the pot: down low in the mismatched parts.
By reducing the gain you can use a more "matched" section of the pot.

Now you get smart on me and say you have a stepped attenuator and matching is very good even at low levels. Thats cool, steppers are pimp!
What is important here is that many steppers offer better control in the middle and max of their range IE: the first 3 or4 steps are BIG, and then they are smaller after that. This is important if you want to have good control over the volume of differently recorded/mixed music. If you normally listen on the first step or 2, you may find yourself choosing between too quiet or blast.

Having said all of that, a general recommendation if you have gain control:
use whatever gain allows you to spin the pot to middle or so. Dont fear the higher side of the pot, there is still plenty of music beyond the middle of its spin. by doing this you will be in a well matched section and have good control over widely varying music selections. Nice!

 

[tintin47]

That was a beautiful explanation, Nikongod. Couldn't have said it better myself and haven't seen it put better anywhere either.

 

[Max F]

Three questions:

I know that higher gain amplifies the signal, does it also amplify the noise?

Does having the volume at the lower end of the dial (higher attenuation) change the sound?

Does gain have anything to do with impedance of the headphones (the above explanation only explain added gain based on the sensitivity of the headphone - i.e., how loud it can go at a given voltage)?

 

[terriblepaulz]

On my amp, my "gain" switch is actually an attenuator on the input, with the "highest" gain setting being the least attenuation (0 db), along with -10, -20, and -30 db settings. At least that's how the builder explained it to me.

 

[milkweg]

OK, thanks for the explanations from everyone. Much appreciated and now I have a better understanding of what it does.