Q701 with O2 Question - Page 2

Quote:

Originally Posted by MrMateoHead 

I don't think it is a "myth". But I do think that the O2 can do about 500-700 mWs at 60 Ohms. That should be more than enough, under most, but not all listening conditions. See my Innerfidelity specs posted above.

 

The next step would be to seek an amp of 1 watt or more, but this wouldn't add a lot of loudness given the large expense (with the exception of 2 amps I can think of).

I own a pair of Q701s, I can drive them with an iPod, an iPad, a FiiO E17, a note book computer, none of these are known for outputting massive amounts of power.

They aren't that power hungry, 20, 30, 40, 50 milliWatts @ 62 Ohms is enough to drive them to any sane volume.

The OP probably thinks we are crazy, he seems to be fine with his O2.  See his last couple of posts.

Quote:

Originally Posted by Chris J 

 

 

A linear or log pot has nothing to do with this.

Obviously have a different definition of "proportional"

Quote:

Originally Posted by jimmers 

Obviously have a different definition of "proportional"

Position of volume control is directly proportional to how much voltage the Headphone amp is outputting.

9 o'clock:   low output voltage

12 o'clock, more output voltage

3 o'clock, even more output voltage.

sure, most of your sensitive range is at the low end with a linear pot. Not good.

sure a poor log pot is preferred to a linear pot (i.e. a "poor log pot" which does not follow the logarithmic scale very well)

sure, a superior log pot is preferred to a poor log pot

Not sure what your definition of proportional is????????????

Quote:

Originally Posted by Chris J 

 

I own a pair of Q701s, I can drive them with an iPod, an iPad, a FiiO E17, a note book computer, none of these are known for outputting massive amounts of power.

They aren't that power hungry, 20, 30, 40, 50 milliWatts @ 62 Ohms is enough to drive them to any sane volume.

 

The OP probably thinks we are crazy, he seems to be fine with his O2.  See his last couple of posts.

You are basically correct, because 50 milliwatts would take the 701s to about 105 dB, in theory. Considering that so much music is horribly compressed these days, I am sure they are loud enough.

But just because you "can drive" a headphone with something, it doesn't mean it is "efficient". I am making my judgement based on how the 701s compare to other headphones, and frankly, they have sucky efficiency, and require a lot of power by comparison. That common devices can still drive them is a testamant to the fact that, in most cases, audiophiles claiming you need an amp to "properly" drive them is BS.

Anyway, I just said that he would be find "under most conditions". My computer with a 1V source was barely cutting it for high dynamic range recordings and movies through my Orthos. Only more power would overcome that. The O2 makes it possible for me to enjoy 90% of whatever source material I have to listen to, and that is the major reason I bought it.

Quote:

Originally Posted by Chris J 

Position of volume control is directly proportional to how much voltage the Headphone amp is outputting.

 

Not sure what your definition of proportional is????????????

y = kx where k is a constant, y is proportional to x

in this case " voltage the Headphone amp is outputting" = k(angular rotation of control)

65 Ohms with 105db SPL/mW is sensitive IMO.

If something can drive the HD650 well, it can definitely drive these.

Quote:

Originally Posted by proton007 

65 Ohms with 105db SPL/mW is sensitive IMO.

If something can drive the HD650 well, it can definitely drive these.

The 300 ohm impedance of the 650 means that it relies on a decent voltage swing to deliver power, while the 701 is more dependent on the low output impedance of an amp - i,e. ability to provide high current. This means that an amp with a high output impedance may be perfect for the 650, but will not cut it for the 701.

Quote:

Originally Posted by PleasantSounds 

 

The 300 ohm impedance of the 650 means that it relies on a decent voltage swing to deliver power, while the 701 is more dependent on the low output impedance of an amp - i,e. ability to provide high current. This means that an amp with a high output impedance may be perfect for the 650, but will not cut it for the 701.

Agreed.

A quick calculation will suggest that the 701 needs ~150mW of power to hit 115dB  peaks, going by 105db/V.

Usually, power rating reduces with the increase in impedance, because amps are primarily a voltage source.

Something that can provide even 80mW at 300 Ohms (or higher) should be able to provide 150mW at 65 Ohms.

Quote:

Originally Posted by Chris J 


This is a circular argument (no pun intended).
I assume you have no idea how electrinics works.
No more discussion on my part.

my sentiments entirely, except I would have used the word "electronics". I admit I have no idea how electrinics works

Slightly different setup, X-Fi going into an A9 FiiO amp and I have similar results. However there is a difference here, I was using 880's direct to X-fi with no problems for the longest time. I could get good volume out of it direct but not exactly slamming loud. But I noticed that 0 to 50% volume worked normal, but 50% to 100% it barely changed.

With my E9 in the loop, that 50% to 100% makes a huge diff now

With loud sources and ones that use a lot of dynamic compression like 90% of the crap they produce these days, the Amp isn't going to do much more than give you another 10db to play with.

But on dynamic source material like acoustic, movie, and classical, it gives you the head room for some truly wonderful experiences.

If you want to know what I mean by Dynamic, put on the 1812 overture with report. Turn it up to a comfortable listening volume. If you can let the song play out without touching the volume control and without distorting, then you have a dynamic set up. If you have to keep tweaking volume, or it gets so loud it distorts, you don't.
 

Quote:

Originally Posted by Chris J 

 

I own a pair of Q701s, I can drive them with an iPod, an iPad, a FiiO E17, a note book computer, none of these are known for outputting massive amounts of power.

They aren't that power hungry, 20, 30, 40, 50 milliWatts @ 62 Ohms is enough to drive them to any sane volume.

 

The OP probably thinks we are crazy, he seems to be fine with his O2.  See his last couple of posts.

I THOUGHT this was true. I bought the Q701's for both gaming and music. While my X-Fi-Gamer,Astro Mix Amp (without chat mixed in/and my Sony MP3 player could drive the Q701's to a decent volume level I failed to appreciate how much they DO need and amp to sound their best. 

I got by without an amp for about a year. I was afraid that an amp would do nothing more than make them louder so I put off investing in one. Once I had the disposable scratch I went for it. I built myself a custom Objective 2 because I wanted to be sure that the amp was not coloring the sound.

RESULT: After much careful AB testing I have found that:

1. It is best to set the sound card output to less than 50% to prevent clipping and distortion coming from the sound card output.

2. Either Gain setting of the O2 is enough but I find that the x 6.0 gain to be the best setting for less than 50% from the sound card and less than 50% from the O2.

3. The end result is most noticeable in the power hungry low frequencies. Without an amp the low bass is flabby, weak and uncontrolled. With an amp it has punch and depth and does not distort the low or mids as much.

It is not night and day mind you. It's not like No amp = crap, Amp = utter bliss.

But IMO one should not buy the Q701's without getting an amp.

Before I got the O2 I found the Q701's inadequate for Rap/Hip Hop, or say DnB. After getting the Amp I find them to perform beautifully with everything I throw at them. 

Please take my opinion as one who does not like to spend money where it is not needed. I do not own 50 pairs of headphone and 20 amps. I wanted to spend the cash on just one good setup and to only do it once. I wanted one setup for Movies Music and Gaming.

After completing a long careful process I feel that I have arrived.

I have: Astro Mixamp, X-fi Extreme Gamer (only thing I might upgrade), Q701's, O2 amp.

I am Very Very happy.

Amen Heretic. You sound like me.