[The Speaker Guy]

Are standard line levels sufficient for achieving max volumes on headphones? That is, can a unity gain amp be used by itself, in conjunction with a passive volume control, to achieve suitable loudness?

I don't have a particular headphone in mind; I currently use generic cheapies. I'm looking to upgrade.

Whatever circuit would have its offset nulled, of course.

What are your thoughts?

 

[jnewman]

Quote:

Originally Posted by The Speaker Guy Are standard line levels sufficient for achieving max volumes on headphones? That is, can a unity gain amp be used by itself, in conjunction with a passive volume control, to achieve suitable loudness? I don't have a particular headphone in mind; I currently use generic cheapies. I'm looking to upgrade. Whatever circuit would have its offset nulled, of course. What are your thoughts?

Standard gain in a headphone amp is between 3 and 5. Plug a pair of headphones in to the "line out" (NOT headphone out) on a CD player and you'll see how loud line level is - an alright listening level for low-impedance cheapie phones, but most nice pairs of cans won't be loud enough.

 

[Earwax]

Take a look at the Szekeres Amp -- I believe that's the type of amp you are talking about (gain of 1). It's supposed to be good for low impedance headphones that don't need much voltage gain.

 

[amb]

With low impedance phones (such as Grados, ~32 ohms) unity gain is usually sufficient. However with high impedance phones (e.g., Sennheiser HD600/650, ~300 ohms) a voltage gain of 5 or so is good. Even higher impedance phones (e.g., old Beyer Dynamic ~600 ohm) may need even higher gain. This is assuming you have a volume control pot or stepped attenuator at the input of the amp, such that you get comfortable listening levels when the knob is about mid-way up.

So, there is no "one size fits all" answer. If you intend to make one amp work with a variety of headphone types, a volume control plus a gain switch would be a good idea.

 

[rickcr42]

depends on what preceeds the "amp" and what the final drive requirements of the headphones are.Voltage drive,current drive-both important


a unity gain buffer or voltage follower stage is more than adequate if it is used after a line stage (preamplifier) or if following a CD/DVD player (needs a volume pot) which usually outputs 2 volts or better but if used after a low gain device such as a portable source then it will need some help to provide good volume levels.

if used on the tape record outputs of a preamplifier , again a gain stage or "full" headphone amp will be required as these outputs come from the input selector and before the volume control or any gain stages.
For most this is a desireable place to tap the signal for heaphone listening because it adds nothing to the signal going to the amp but if your line stage is good enough the unity gain option is a good one.Think of this connection as a simple source selector.

BTW-the "amp" then becomes a headphone driver instead of a headphone amp