[cel4145]

couldnt seem to take the front panel off together with the knob, im pretty sure i need to remove it first

yep, looks like an allen key is what i need. thank you very much

You don't have to take the knob off to get to the battery. The faceplate will just come off with the board as you slide it out.

 

[adamlr]

Quote:

You don't have to take the knob off to get to the battery. The faceplate will just come off with the board as you slide it out.

your not the first to tell me this, but i tried removing the front panel, and it wouldnt budge. i tried removing the back panel aswell but one of the screws wouldnt give...
 
is there something i should be doing? is there more to it than just unscrewing the screws?

 

[cel4145]

Then maybe you should take off the knob since you are having problems (you need a small non-metric hex key). That way you don't accidentally yank the knob and its connection to the board when you pull the cover off. I changed out my front plate, and there was a touch of hot glue holding it to the board. With the plate glued to the board, it has to pull straight out, not at an angle or off kilter in someway.

 

[miceblue]

Quote:

 

and as for the second part of your post, im given to understand that for maximum fidelity, you want to control volume with your amp, not your source. having your source on 100% will deliver the maximum quality, and if its on less, you could be delivering like, 12 bits of digital audio to your amp, as opposed to 16 bits, if the volume was at 100%. granted, i have no idea if this is true, even if it is, i dont know how audible the difference will be and ofcourse, im in no way an authority on these issues.

 
That's the same impression that I got from reading other posts about this subject. If you have a 16 bit dac and your files are 16bit, lowering the volume in windows lower your dynamic range / quality of the output. You want to control the volume via the amp. The other bit that I gleemed from this is that if you set the dac to 24 bit and your audio files are 16 bit, you can lower the volume in windows up to a point w/o effecting dynamic range since the dac will take the 16 bit file and upconvert it to 24 and fill in the missing 8bit with just 0s so you can change the volume in windows and all you're losing is 8bits worth of 0s.

Hm I see. Thanks for the clarification.
 
I still don't really like that that happens though. With my Retina MacBook Pro on max volume, the O2 set to as low of volume as possible at 1.0x gain, they are super loud for me with the K 701....which basically renders the O2 useless for the M-100 if the O2's potentiometer is at the 7:30 position (yes there's channel imbalance) for the K 701 even at 1.0x gain. With this kind of listening, I can't physically lower the volume with the amp any more or else I will get a really noticeable channel imbalance. All of this seems unreasonable to me.
 
The creator of the O2 did point out "guilty free" source volume control with the ODAC's 24-bit USB interface and gave a brief sentence or two about the loss of resolution and whatnot. The question is, can you guys actually hear it? I notice no significant increase in sound quality, if any, with the source on max volume, super-limited volume control with the amp versus low volume on source, very diverse volume control with the amp.

 

[adamlr]

Quote:

Then maybe you should take off the knob since you are having problems (you need a small non-metric hex key). That way you don't accidentally yank the knob and its connection to the board when you pull the cover off. I changed out my front plate, and there was a touch of hot glue holding it to the board. With the plate glued to the board, it has to pull straight out, not at an angle or off kilter in someway.

actually, the plate came loose pretty easily, it felt like it was entirely loose, and the only thing that was holding it back was the volume knob. unfortunately, i dont have an allen key thats small enough, which is really ironic, as i ordered a full set of them off ebay a couple of months ago on a whim, and just yesterday i sent the guy an email, cause they haven't arrived yet >_<
 
looks like the batteries will remain inside for the time being. i just want to take them out so as to make the O2 a "desktop amp" and use the mains to power it, without any batteries to worry about. supposedly you can leave it plugged in for decades and it wont damage the batteries at all, but im skeptical, and want to remove them just in case anyway.

 

[adamlr]

Quote:

Hm I see. Thanks for the clarification.
 
I still don't really like that that happens though. With my Retina MacBook Pro on max volume, the O2 set to as low of volume as possible at 1.0x gain, they are super loud for me with the K 701....which basically renders the O2 useless for the M-100 if the O2's potentiometer is at the 7:30 position (yes there's channel imbalance) for the K 701 even at 1.0x gain. With this kind of listening, I can't physically lower the volume with the amp any more or else I will get a really noticeable channel imbalance. All of this seems unreasonable to me.
 
The creator of the O2 did point out "guilty free" source volume control with the ODAC's 24-bit USB interface and gave a brief sentence or two about the loss of resolution and whatnot. The question is, can you guys actually hear it? I notice no significant increase in sound quality, if any, with the source on max volume, super-limited volume control with the amp versus low volume on source, very diverse volume control with the amp.

hmmm, thats bad news i guess... but no, i doubt many people can really hear a difference. infact, if you look on youtube, you can find a video by ethan winer that shows you cant really hear any effect on quality untill you get as low as 8-10 bits, so i guess it really isnt such a big issue using digital volume control. i would greatly appreciate it if you pm me a link to the forbidden blog with that brief sentence, or atleast tell me which article it was in, id really like to read it. 
 
then again, if even *1 is too much for the m-100, perhaps theres no use snipping my O2, as ill likely have to use digital volume control anyway...
 
by the way, pardon my newbe question, but how is *1 gain even possible? wouldnt *1 give you the same value you were multiplying in first place? i think ive got something very wrong...
 
edit: forgot to add that i have no idea what im talking about, everything i have written is in my very humble opinion, if anyone can hear a difference between 24bit audio and otherwise then i wish him the best of luck with it, and in no way am i trying to pick a fight with anyone, or question their believes or anything of the sort.

 

[MrEleventy]

Quote:

Hm I see. Thanks for the clarification.
 
I still don't really like that that happens though. With my Retina MacBook Pro on max volume, the O2 set to as low of volume as possible at 1.0x gain, they are super loud for me with the K 701....which basically renders the O2 useless for the M-100 if the O2's potentiometer is at the 7:30 position (yes there's channel imbalance) for the K 701 even at 1.0x gain. With this kind of listening, I can't physically lower the volume with the amp any more or else I will get a really noticeable channel imbalance. All of this seems unreasonable to me.
 
The creator of the O2 did point out "guilty free" source volume control with the ODAC's 24-bit USB interface and gave a brief sentence or two about the loss of resolution and whatnot. The question is, can you guys actually hear it? I notice no significant increase in sound quality, if any, with the source on max volume, super-limited volume control with the amp versus low volume on source, very diverse volume control with the amp.

 
My current setup is E17 LO > O2 > M80s, looking at the specs, it's not too far off from the M-100s (28.5 ohms vs 32 ohms, 105db vs 103db), what I do, since all 99% of my files are 16 bit anyways, I set my E17 to run at 24bit and lower the volume by about 25% and that gives me more wiggle room on the O2. I don't know the exact math but doing my own fuzzy math, I figure since 16 to 24 is about 66.7%, I can throw away 33% before losing "quality". I actually don't notice a difference at 50% but my OCD goes off and I crank it back up. 

 
P.S. My O2 is still on the defaulted 2.5x/6.5x, FWIW.

 

[adamlr]

Quote:

 
My current setup is E17 LO > O2 > M80s, looking at the specs, it's not too far off from the M-100s (28.5 ohms vs 32 ohms, 105db vs 103db), what I do, since all 99% of my files are 16 bit anyways, I set my E17 to run at 24bit and lower the volume by about 25% and that gives me more wiggle room on the O2. I don't know the exact math but doing my own fuzzy math, I figure since 16 to 24 is about 66.7%, I can throw away 33% before losing "quality". I actually don't notice a difference at 50% but my OCD goes off and I crank it back up. 

 
P.S. My O2 is still on the defaulted 2.5x/6.5x, FWIW.

this sounds good to me, as im probably going to get the m-100s and im hoping not to have to mess around with the insides of my O2. what i dont undestand is this: my setup is laptop>odac>O2>headphones. so infact, no matter what bit depth i set my odac to, the original files are still being sent through my laptop, so if i lower the volume on my computer, less than the full quality is being sent to the odac, which i assume will compensate by a higher amount of "fake" bits, and not actually solving the volume control issue, no?
 
and in the hopes of getting an answer, ill quote myself:
by the way, pardon my newbe question, but how is *1 gain even possible? wouldnt *1 give you the same value you were multiplying in first place? i think ive got something very wrong...

 

[cel4145]

looks like the batteries will remain inside for the time being. i just want to take them out so as to make the O2 a "desktop amp" and use the mains to power it, without any batteries to worry about. supposedly you can leave it plugged in for decades and it wont damage the batteries at all, but im skeptical, and want to remove them just in case anyway.

These are the same ones. $9 to replace if you wear them out.

 

[shadow419]

*1 is unity gain. It's also called a buffer at this point since your not increasing the voltage, but you can still provide more power through increased current capability

 

[adamlr]

Quote:

These are the same ones. $9 to replace if you wear them out.

 
thank you, but im not worried about wearing them out, im worried that with time, constantly being plugged in and charging, theyll die and damage the amp, not necessarily the most reasonable fear, but id still rather just take them out, leave the amp plugged in, and forget about it.
 
Quote:

*1 is unity gain. It's also called a buffer at this point since your not increasing the voltage, but you can still provide more power through increased current capability

thank you, so i was half right? *1 does infact mean that your left with the same voltage, i guess thats why its called "unity gain"? so, *1 gain means that you only add current? and this still sounds the same? doesnt it react differently to your headphones specs as opposed to "regular" gain?

 

[miceblue]

Quote:

Quote:

Hm I see. Thanks for the clarification.
 
I still don't really like that that happens though. With my Retina MacBook Pro on max volume, the O2 set to as low of volume as possible at 1.0x gain, they are super loud for me with the K 701....which basically renders the O2 useless for the M-100 if the O2's potentiometer is at the 7:30 position (yes there's channel imbalance) for the K 701 even at 1.0x gain. With this kind of listening, I can't physically lower the volume with the amp any more or else I will get a really noticeable channel imbalance. All of this seems unreasonable to me.
 
The creator of the O2 did point out "guilty free" source volume control with the ODAC's 24-bit USB interface and gave a brief sentence or two about the loss of resolution and whatnot. The question is, can you guys actually hear it? I notice no significant increase in sound quality, if any, with the source on max volume, super-limited volume control with the amp versus low volume on source, very diverse volume control with the amp.

 
My current setup is E17 LO > O2 > M80s, looking at the specs, it's not too far off from the M-100s (28.5 ohms vs 32 ohms, 105db vs 103db), what I do, since all 99% of my files are 16 bit anyways, I set my E17 to run at 24bit and lower the volume by about 25% and that gives me more wiggle room on the O2. I don't know the exact math but doing my own fuzzy math, I figure since 16 to 24 is about 66.7%, I can throw away 33% before losing "quality". I actually don't notice a difference at 50% but my OCD goes off and I crank it back up. 

 
P.S. My O2 is still on the defaulted 2.5x/6.5x, FWIW.

Ah okay, 75% volume sounds reasonable. With the 2.5x gain I can hear the background hiss of the O2 though (I posted this in a previous post here), so that's why I keep to the 1.0x; that plus John of JDS Labs recommended the 2.5x/1.0x for low-volume listening.

 

[lorriman]

Hm I see. Thanks for the clarification.

I still don't really like that that happens though. With my Retina MacBook Pro on max volume, the O2 set to as low of volume as possible at 1.0x gain, they are super loud for me with the K 701....which basically renders the O2 useless for the M-100 if the O2's potentiometer is at the 7:30 position (yes there's channel imbalance) for the K 701 even at 1.0x gain. With this kind of listening, I can't physically lower the volume with the amp any more or else I will get a really noticeable channel imbalance. All of this seems unreasonable to me.

The creator of the O2 did point out "guilty free" source volume control with the ODAC's 24-bit USB interface and gave a brief sentence or two about the loss of resolution and whatnot. The question is, can you guys actually hear it? I notice no significant increase in sound quality, if any, with the source on max volume, super-limited volume control with the amp versus low volume on source, very diverse volume control with the amp.

There's a further complication in that there may be a difference between XP and Vista/7. the suggestion I'e seen is that XP is affected by the 16bit volume issue (necessitating max source volume) but Vista/7 aren't. Apparently XP had an infamous sound system that would do this bit-stripping, as I've seen it called, but Vista/7 aren't affected. It would be good to get a clarification of that. Perhaps it's because Vista/7 default to 24 bit, or perhaps they talk to the amp circuit directly somehow. However, the ODAC horrifyingly defaults to 16bit on my Vista computer which I didn't know for some time, so perhaps not the former. Of course, this could be entirely bogus: in that all 3 OS's are affected equally.

In any case, I tried XP at 16bit mode and reduced source volume to a minimum using my O2 to amplify: I didn't hear much difference. But I would have to repeat that test to be sure of my claim there which I can't do at the moment.

The main things is that most modern sound cards can be easily switched to 24bit mode on Windows which means you can turn the source way down, with all the advantages that brings (and one disadvantage). I would be surprised if there were not some way of verifying that on your MAC, or changing it. (The disadvantage is that some forms of noise can be made inaudible by turning the volume to max on the source and turned down on the amp/O2. )

 

[MrEleventy]

Quote:

this sounds good to me, as im probably going to get the m-100s and im hoping not to have to mess around with the insides of my O2. what i dont undestand is this: my setup is laptop>odac>O2>headphones. so infact, no matter what bit depth i set my odac to, the original files are still being sent through my laptop, so if i lower the volume on my computer, less than the full quality is being sent to the odac, which i assume will compensate by a higher amount of "fake" bits, and not actually solving the volume control issue, no?

 
Volume adjustment is post conversion. It gets adjusted right before going out the 3.5mm jack.
 
Quote:

Ah okay, 75% volume sounds reasonable. With the 2.5x gain I can hear the background hiss of the O2 though (I posted this in a previous post here), so that's why I keep to the 1.0x; that plus John of JDS Labs recommended the 2.5x/1.0x for low-volume listening.

 
That's weird. I don't get a hiss with either gain on mine. My O2 isn't a JDS Labs though. Built by a Head-Fier.

 

[adamlr]

Quote:

 
Volume adjustment is post conversion. It gets adjusted right before going out the 3.5mm jack.
 

i still dont get it, if you adjust the volume on the computer, then youv degraded the sound BEFORE it even reaches your dac. unless the digital volume control is somehow controlling your dacs volume?? i went on "the blog that must not be named" and read up on the odac. he says you can control volume digitaly without loosing fidelity, but he doesnt explain why its possible, just gives the same explanations as given here...