Hello all, I have some questions involving headphone amplifier power and relation to volume control.
A little background: I am building a tubelab SE-II, which supports 45, 2A3, or 300B output tubes. My goal is to build a headphone amplifier out of this circuit. When gathering opinions on what output tubes I should get, everyone said go 45, because they have less output power, and the wattage of 2A3's and 300B's (about 3.5w and 8w respectively), would blow out my drivers and my ears.
But here's the thing... There are tons of tube amps out there that output 5+ watts of power into headphones, including the ampsandsound Mogwai SE I have, and I've never had a problem at all with "blowing out my headphones". I also confirmed with Justin of ampsandsound that there are no resistive networks, and that the full output power of the taps are put into the headphones, but volume control is used to attenuate to the listener's desired level. So I don't quite understand the worry from folks about blowing out my headphones with more powerful tubes. Maybe they assumed that I wouldn't be using volume control in my amp?
Anyway, Here are my questions:
1. If a headphone amp has the capability to dump 5w into headphones, would the headphones only receive all 5w if the volume pot was set to max volume? That would explain amps that can output many watts, but don't damage headphones.
2. If yes to the previous question... what's the point of having a headphone amp that can put 5w into headphones only to have it reduced significantly by a volume pot?
3. Is there any detriment to sound quality from using only a partial amount of the input signal (from turning down the volume pot)?
4. Does this mean most headphone amps can be made to output MUCH less than 5w and still be able to drive "hard-to-drive" headphones, with the only side effect being that the volume knob has to be turned up higher?
I'd appreciate any input on this. I am new to diy audio projects, and there are still some gaps in my knowledge.
A little background: I am building a tubelab SE-II, which supports 45, 2A3, or 300B output tubes. My goal is to build a headphone amplifier out of this circuit. When gathering opinions on what output tubes I should get, everyone said go 45, because they have less output power, and the wattage of 2A3's and 300B's (about 3.5w and 8w respectively), would blow out my drivers and my ears.
But here's the thing... There are tons of tube amps out there that output 5+ watts of power into headphones, including the ampsandsound Mogwai SE I have, and I've never had a problem at all with "blowing out my headphones". I also confirmed with Justin of ampsandsound that there are no resistive networks, and that the full output power of the taps are put into the headphones, but volume control is used to attenuate to the listener's desired level. So I don't quite understand the worry from folks about blowing out my headphones with more powerful tubes. Maybe they assumed that I wouldn't be using volume control in my amp?
Anyway, Here are my questions:
1. If a headphone amp has the capability to dump 5w into headphones, would the headphones only receive all 5w if the volume pot was set to max volume? That would explain amps that can output many watts, but don't damage headphones.
2. If yes to the previous question... what's the point of having a headphone amp that can put 5w into headphones only to have it reduced significantly by a volume pot?
3. Is there any detriment to sound quality from using only a partial amount of the input signal (from turning down the volume pot)?
4. Does this mean most headphone amps can be made to output MUCH less than 5w and still be able to drive "hard-to-drive" headphones, with the only side effect being that the volume knob has to be turned up higher?
I'd appreciate any input on this. I am new to diy audio projects, and there are still some gaps in my knowledge.
The volume control adjusts the overall voltage gain, by varying its own attenuation of the signal.
This is relative to the signal level at the input, so the volume control does not determine the absolute
output level. It just increases or decreases the input level.
It's hard to believe that anyone would ever want 5W into any headphones, at least more than once.
This is relative to the signal level at the input, so the volume control does not determine the absolute
output level. It just increases or decreases the input level.
It's hard to believe that anyone would ever want 5W into any headphones, at least more than once.
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Ok, I think I see. If I understand you correctly, an amp outputs it's maximum amount of power when the input signal meets the amp's input sensitivity voltage? So then, if the volume control limits that voltage, the amp is not producing it's maximum wattage into the headphones, because the input voltage is less.
Yes, if you use a digital source, which has a defined maximum peak level, then you can calculate
the total combined gain necessary in the preamp and amplifier to reach the maximum amplifier output.
Then if there is enough gain, the volume control's range will allow reaching full amplifier output, when
it is set either at maximum, or somewhat below that.
..
the total combined gain necessary in the preamp and amplifier to reach the maximum amplifier output.
Then if there is enough gain, the volume control's range will allow reaching full amplifier output, when
it is set either at maximum, or somewhat below that.
..
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Gotcha! I understand now! So (just thinking out loud here for my own benefit), with something like the Mogwai SE (3-6 watts depending on tubes), there's nobody that's actually running it anywhere near that maximum wattage. I can barely get past 9 or 10 o'clock with mine on most headphones before it becomes too loud. So really, when a headphone amp advertises that much wattage, it's mostly for show, as nobody will listen nearly loud enough to where the volume pot is at maximum.
So that means I should be able to use 2A3's or 300B's in my headphone amp, as long as I have volume control on the amp to tone down the input voltage.
So that means I should be able to use 2A3's or 300B's in my headphone amp, as long as I have volume control on the amp to tone down the input voltage.
Yes, I doubt that anyone would ever want to run headphones that loud.
This amp has no feedback, so its gain is not well controlled with parts variations.
A lot of unused gain (it's all, or mostly, after the volume control) just increases the noise level.
This amp has no feedback, so its gain is not well controlled with parts variations.
A lot of unused gain (it's all, or mostly, after the volume control) just increases the noise level.
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