[ProtegeManiac]

Though I wish I could clearly picture your Gundam analogy, I can only imagine the outer shell of a generic Gundam for now I watched Gundam 00 long time ago by my friend's recommendation, and I thought it was decent. I'll probably give seed and destiny a try when I get the time

Just think of how the cockpit controls look like where the one thing consistent through nearly all the different series is that there are throttles (as in on a plane) on either side of the pilot's seats (transformable mobile suits have an alternate joystick when in fighter form) that controls the arms and torso. If you remember the fight scenes, when the pilot gets angry or whatever and lunges forward you'll see his whole torso lunge forward as he moves both throttles forward (and then cut to the mobile suit moving forward), other times flying with the left (sheild) arm forward then the pilot suddenly throws the right throttle forward (and presumably moves the left throttle backward) and the suit is shown to suddenly swing the shield aside, torso twists, right arm thrusts forward with a sword (or spear or halberd, whatever each suit has), etc. Gentle push on throttle = gently reaching out; violently pushing throttle forward = act of violence by (usually the right) arm.

It's like a with a knob - twist right and you get max volume, twist left and you get nothing (or imbalance). Volume + and - buttons work differently - press one and the adjustment starts out gradually then goes faster as it realizes, albeit slowly, that you want to go all the way.

I still don't really understand question 4 though, how does lower-than-optimal? voltage on a DAC make lower gain on an amp better?

DAC output signal is input signal into amp that will be amplified. The lower the voltage of the input signal, given the same amp and headphone downstream, then the output in dB will be lower. If you have imbalance until 9:00 on the dial but that's too loud with one DAC, then a lower voltage input to the amp would make the final output lower, thus you can move the volume knob higher and get past the imbalance zone. This still depends on other factors however as 1.5V vs 2V might have appreciable differences on that amp and headphones, but not necessary 1.2V vs 1.5V.

So in a very simplistic sense, think of it as XY(Z) = A (note that this is an extremely simplistic representation) where

X = input signal voltage
Y = amp gain and power
Z = headphone sensitivity
A = actual output in dB

So basically, assuming the amp and headphone are constant:

Schiit Modi2 Uber : 1.5Y(Z) = A*
Fiio Q1 : 1.2Y(Z) = A**

A* > A** at the same volume setting until max, so you can now turn it up the point where there is no imbalance in the potentiometer but the resulting output will not be as loud as when using the 1.5V Modi2U.

That said, again, if the Modi2U at 1.5V is waaaaay too loud for you at the balanced signal point, going down to 1.2V might not be guaranteed fix.

----


One other thing though - are you sure you have this switch set to "Low?"

 

[RadioHamster]

Just think of how the cockpit controls look like where the one thing consistent through nearly all the different series is that there are throttles (as in on a plane) on either side of the pilot's seats (transformable mobile suits have an alternate joystick when in fighter form) that controls the arms and torso. If you remember the fight scenes, when the pilot gets angry or whatever and lunges forward you'll see his whole torso lunge forward as he moves both throttles forward (and then cut to the mobile suit moving forward), other times flying with the left (sheild) arm forward then the pilot suddenly throws the right throttle forward (and presumably moves the left throttle backward) and the suit is shown to suddenly swing the shield aside, torso twists, right arm thrusts forward with a sword (or spear or halberd, whatever each suit has), etc. Gentle push on throttle = gently reaching out; violently pushing throttle forward = act of violence by (usually the right) arm.

It's like a with a knob - twist right and you get max volume, twist left and you get nothing (or imbalance). Volume + and - buttons work differently - press one and the adjustment starts out gradually then goes faster as it realizes, albeit slowly, that you want to go all the way.

I did understand what you said, but now that I google'd a picture of Gundam cockpit, your description comes more vivid I just couldn't picture it clearly in my head since it was too long ago.

DAC output signal is input signal into amp that will be amplified. The lower the voltage of the input signal, given the same amp and headphone downstream, then the output in dB will be lower. If you have imbalance until 9:00 on the dial but that's too loud with one DAC, then a lower voltage input to the amp would make the final output lower, thus you can move the volume knob higher and get past the imbalance zone. This still depends on other factors however as 1.5V vs 2V might have appreciable differences on that amp and headphones, but not necessary 1.2V vs 1.5V.

So in a very simplistic sense, think of it as XY(Z) = A (note that this is an extremely simplistic representation) where

X = input signal voltage
Y = amp gain and power
Z = headphone sensitivity
A = actual output in dB

So basically, assuming the amp and headphone are constant:

Schiit Modi2 Uber : 1.5Y(Z) = A*
Fiio Q1 : 1.2Y(Z) = A**

A* > A** at the same volume setting until max, so you can now turn it up the point where there is no imbalance in the potentiometer but the resulting output will not be as loud as when using the 1.5V Modi2U.

That said, again, if the Modi2U at 1.5V is waaaaay too loud for you at the balanced signal point, going down to 1.2V might not be guaranteed fix.

Oh I see, I thought you were saying I have to go higher than 1.5V. But I do understand the basic concept of lower input voltage => lower output current.

One other thing though - are you sure you have this switch set to "Low?"

I have the gain on low setting. However, until my HD6xx arrives, I'm using my HD598 which only has output impedance of 50 ohms. I'm having to turn the knob almost all the way counter-clockwise

 

[castleofargh]

I have the gain on low setting. However, until my HD6xx arrives, I'm using my HD598 which only has output impedance of 50 ohms. I'm having to turn the knob almost all the way counter-clockwise

no big deal, but you want to use sensitivity in reference to the loudness you get for a given voltage or power, as it's exactly what the sensitivity measures. impedance serves other roles in the specs, like converting voltage value into power value or vice versa when we need it.

 

[RadioHamster]

no big deal, but you want to use sensitivity in reference to the loudness you get for a given voltage or power, as it's exactly what the sensitivity measures. impedance serves other roles in the specs, like converting voltage value into power value or vice versa when we need it.

Yup, I indeed heard that sensitivity is what matters in the end.

However, after reading that, I went to check the sensitivity of HD598 and HD6xx out of curiosity, and I found out HD598 has 100.71 dB SPL/mW and HD6xx has 103 dB SPL/mW. Does this mean HD6xx is easier to drive? Because that's contrary to what I've been hearing on this forum. Are there other factors to consider?

 

[castleofargh]

Yup, I indeed heard that sensitivity is what matters in the end.

However, after reading that, I went to check the sensitivity of HD598 and HD6xx out of curiosity, and I found out HD598 has 100.71 dB SPL/mW and HD6xx has 103 dB SPL/mW. Does this mean HD6xx is easier to drive? Because that's contrary to what I've been hearing on this forum. Are there other factors to consider?

hd650 is given at something like 102 or 103dB/V by Sennheiser
hd598 is given at 112dB/V
so if those values are what you'll get on your headphones, the 598 is going to sound about twice as loud subjectively(about +10dB) when fed with the same voltage output(where you turn the knob) at the amplifier.
it's important to check the units for sensitivity because sometimes we miss different units. and not just us, there are plenty of misquoted sensitivities on websites online.

about people discussing "hard to drive", good luck finding 10 people who have the same thing in mind when they tell you about how hard something is to drive. the very concept of easy to drive isn't clearly quantified, we don't have a rule where if a headphone is above 50ohm and can reach 110dBspl into less than 2V then it's "easy to drive". instead everybody's free to make their own reference and definition, even purely subjective ones.

 

[RadioHamster]

hd650 is given at something like 102 or 103dB/V by Sennheiser
hd598 is given at 112dB/V
so if those values are what you'll get on your headphones, the 598 is going to sound about twice as loud subjectively(about +10dB) when fed with the same voltage output(where you turn the knob) at the amplifier.
it's important to check the units for sensitivity because sometimes we miss different units. and not just us, there are plenty of misquoted sensitivities on websites online.

about people discussing "hard to drive", good luck finding 10 people who have the same thing in mind when they tell you about how hard something is to drive. the very concept of easy to drive isn't clearly quantified, we don't have a rule where if a headphone is above 50ohm and can reach 110dBspl into less than 2V then it's "easy to drive". instead everybody's free to make their own reference and definition, even purely subjective ones.

Oh, so I downloaded the spec sheet from Sennheiser and it states that it has sensitivity of 103 dB/V. It all makes sense now. There does seem to be quite a bit of misinformation running around the Internet, and it probably has something to do with Sennheiser not mentioning it anywhere other than on a single line on their spec sheet which is only half a page of their multi-language "instruction manual" (also with different unit of 1 Vrms). "Hard to drive" was a concept I didn't get at first, because it seemed like some made-up concept as it is indeed very subjective, but I got used to it from reading a lot on this forum

 

[tomb]

"Hard to drive" with regard to the Sennheiser HD580/600/650 family can be reduced to one thing: they're all 300 ohm impedance. That means a mismatch with typical portable amplifiers, phones, and small DAC-amps. 300 ohms means it needs more voltage than current, compared to the typical 32-ohm headphones that might be paired with portable equipment. Batteries like to provide more current than voltage. So, that headphone family gets the reputation of "hard to drive." The HD598, on the other hand, is a more manageable 50 ohms. The comparison is where the "hard to drive" reputation begins.*

However, any one headphone in that HD580/600/650 family is still far superior to the HD598 - assuming that you have a reasonable quality amplifier to drive it.

* There are always exceptions, but the explanation above is also why tube amps are often recommended for the HD580/600/650 - tubes often run at 100, 200, 300V or more. That said, Chu Moy invented the first CMoy headphone amplifier using an opamp and a 9V battery. The 9V battery under the right circumstances, can provide enough voltage swing to allow the Senn HD580/600/650 to sound pretty good. It sounds a lot better, however, if you build the CMoy to use 2 x 9V batteries.

 

[ProtegeManiac]

I have the gain on low setting. However, until my HD6xx arrives, I'm using my HD598 which only has output impedance of 50 ohms. I'm having to turn the knob almost all the way counter-clockwise

The key there isn't just low impedance, it also has higher sensitivity. That means it doesn't need as much power but the impedance puts it at the range where the Magni3 has a lot of power.

 

[RadioHamster]

"Hard to drive" with regard to the Sennheiser HD580/600/650 family can be reduced to one thing: they're all 300 ohm impedance. That means a mismatch with typical portable amplifiers, phones, and small DAC-amps. 300 ohms means it needs more voltage than current, compared to the typical 32-ohm headphones that might be paired with portable equipment. Batteries like to provide more current than voltage. So, that headphone family gets the reputation of "hard to drive." The HD598, on the other hand, is a more manageable 50 ohms. The comparison is where the "hard to drive" reputation begins.*

However, any one headphone in that HD580/600/650 family is still far superior to the HD598 - assuming that you have a reasonable quality amplifier to drive it.

* There are always exceptions, but the explanation above is also why tube amps are often recommended for the HD580/600/650 - tubes often run at 100, 200, 300V or more. That said, Chu Moy invented the first CMoy headphone amplifier using an opamp and a 9V battery. The 9V battery under the right circumstances, can provide enough voltage swing to allow the Senn HD580/600/650 to sound pretty good. It sounds a lot better, however, if you build the CMoy to use 2 x 9V batteries.

Yup, I got the impression that output impedance and being "hard to drive" are usually correlated. I read that tube amps go well with HD650 but didn't research exactly why. I thought it could be a placebo effect, but what you said kinda makes sense

 

[RadioHamster]

The key there isn't just low impedance, it also has higher sensitivity. That means it doesn't need as much power but the impedance puts it at the range where the Magni3 has a lot of power.

True, as catleofargh and tomb said, impedance and sensitivity both seem to matter for driving a headphone.