[Baird GoW]

Can someone explain gain and what it does in simple terms? And how to know what your gain should be on diff headphones?

 

[swayne]

A gain

Sorry, couldn't resist.

It's been answered. Try here.

Steven.

 

[DennyL]

Gain is simply the ratio of the output voltage divided by the input voltage, and doesn't say anything about impedance or power delivery. It is usually expressed in decibels.

 

[billybob_jcv]

As far as the appropriate gain for different headphones, you want to look at the specs for sensitivity and impedance. Sensitivity is how loud (measured as sound pressure level or SPL) the 'phones are at a specific distance from the driver and a specific input wattage. Impedance is the load the 'phones present to the amplifier, measured in Ohms. So, a "easy to drive" 'phone will have a high sensitivity and low impedance (eg, Sensitivity = 110 dB SPL/mW, Impedance = 32 Ohms), and a "hard to drive" 'phone will have a low sensitivity and high impedance (eg, Sensitivity = 89 dB SPL/mW, Impedance = 300 Ohms). Hard to drive 'phones probably need a high-gain amp, easy to drive 'phones probably need a low-gain amp. One way to find out the appropriate amp gain is to contact the amp manufacturer, tell them what 'phones you have and ask them to recommend a gain setting.

 

[Baird GoW]

Quote:

Originally Posted by billybob_jcv /img/forum/go_quote.gif As far as the appropriate gain for different headphones, you want to look at the specs for sensitivity and impedance. Sensitivity is how loud (measured as sound pressure level or SPL) the 'phones are at a specific distance from the driver and a specific input wattage. Impedance is the load the 'phones present to the amplifier, measured in Ohms. So, a "easy to drive" 'phone will have a high sensitivity and low impedance (eg, Sensitivity = 110 dB SPL/mW, Impedance = 32 Ohms), and a "hard to drive" 'phone will have a low sensitivity and high impedance (eg, Sensitivity = 89 dB SPL/mW, Impedance = 300 Ohms). Hard to drive 'phones probably need a high-gain amp, easy to drive 'phones probably need a low-gain amp. One way to find out the appropriate amp gain is to contact the amp manufacturer, tell them what 'phones you have and ask them to recommend a gain setting.

Perfect thank you, only thing else id like to know is if I can I get an example of a high and low gain portable amp. and what they say that will make it obvious to me there low or high gain like your sensitivity and impetence examples above.
wow you were a great help. thanks if we could give rep I would have.

 

[billybob_jcv]

FYI, I think amp gain is typically expressed as either dB or as a simple multiplier. So, 0 dB = unity gain = 1. That's why some amps say they have a gain of "18 dB", while others will say they have a gain of "5" without specifying the units. (I don't know whether 18 db = gain of 5 - I just picked those 2 numbers at random - someone else can do the math...)

As far as an example, here's what BioScienceGeek says in his ebay ads:

Quote:

Having an amp tweaked to match your gear can make the difference between hiss/distortion and an enjoyable listening experience. The ultra-low noise characteristics of the OPA2227 means noise that normally accompanies high gain is not a major issue. However, using too low a gain for your gear means your headphones will sound weak; too high a gain setting and your phones may distort. Dual gain allows user to boost "fold amplification" to obtain the most robust sound and broadest soundstage from high-impedance or difficult-to-drive headphones and then to drop gain down to accommodate high-sensitivity earphones. The control is an easily-accessible jumper on the amp board. This option is useful for those who have a wide variety of headphones but don't want to buy an amp tailored for each. Best of all, with my amps, when you let me know what types of phones you'll be using, I can set up the dual gain feature of this amp to provide you with two gain settings suitable for your range of gear or applications.

I'm not advocating his amps (although they do appear to be one of the nicer CMoy implementations) - I've never heard the BSG amp. However, that sounds like a pretty sensible approach to me.

Here's what a Stereophile review of an RSA Hornet says:
Stereophile: Ray Samuels Audio Emmeline The Hornet headphone amplifier

Quote:

The Hornet's maximum voltage gains, with its volume control set to its maximum, were 5.6dB, 12.7dB, and 20.8dB with the rear-panel switch set to its Low, Medium, and High positions, respectively.

Also, don't forget that the volume pot is really a gain control...