[shadow419]

Quote:

That doesn't make much sense. I use my O2 as a desktop amp also. Clipping the 2.5x would have given me unity gain for my ultra-sensitives and left me the option of playing from my mp3 player or HD650s (serious desktop headphones).

I've never seen a justification for clipping that 6.5x that adds up.

For some reason people have got this idea of clipping the 6.5x in to their heads (justified by the higher distortion at 6.5x) and encouraged others to do so too, but all it does is limit your options. That higher distortion isn't audible and is irrelevant.

 
Justification for clipping 6.5x gain that adds up:
 
1. You do not intend to use low voltage sources (<=1V) since your dac/soundcard outputs 2V+
2. You don't need gain for sensitive headphones, but enough voltage swing for higher z headphones
 
If you remove the 2.5X option you limit your voltage swing or risk clipping the input.

 

[thecansmancan]

hey all, quick question in regards to the O2. So i know the typical one is bought at JDS or some other such similar retailer. But while on eBay i stumbbled aross this. At $127 its a fair deal cheaper than its JDS counter part. I was curious, do you think there is any real SQ difference or build difference between the two? Anyone have any experience with this one? Thanks so much.

 

[shadow419]

Quote:

hey all, quick question in regards to the O2. So i know the typical one is bought at JDS or some other such similar retailer. But while on eBay i stumbbled aross this. At $127 its a fair deal cheaper than its JDS counter part. I was curious, do you think there is any real SQ difference or build difference between the two? Anyone have any experience with this one? Thanks so much.

He's a much smaller builder, but there are members here that use Mayflower Electronics O2's.  Do a search for Mayflower and I'm sure you'll find threads mentioning him.

 

[adamlr]

Quote:

That doesn't make much sense. I use my O2 as a desktop amp also. Clipping the 2.5x would have given me unity gain for my ultra-sensitives and left me the option of playing from my mp3 player or HD650s (serious desktop headphones).

I've never seen a justification for clipping that 6.5x that adds up.

For some reason people have got this idea of clipping the 6.5x in to their heads (justified by the higher distortion at 6.5x) and encouraged others to do so too, but all it does is limit your options. That higher distortion isn't audible and is irrelevant.

 
Quote:

 
1. You do not intend to use low voltage sources (<=1V) since your dac/soundcard outputs 2V+
 

i use an odac which outputs ~2V (dont remember exactly) and have no use for 6.5x gain. distortion doesnt enter into it. as i mentioned earlier, im not the golden ears type. my reason for wanting unity gain is not for sensitive iems, but for sensitive headphones (m-100: 32 ohm, sensitivity of 103 dB @ 1kHz 1mW).
 
my reasoning behind keeping 2.5x gain? im currently using dt 770s, 250 ohms. i eq rather heavily, dropping frequencies beyond 80hz by 8dB, and dropping frequencies beyond 250 hz by an additional 4 dB, sometimes i eq even more. with this configuration, together with dropping 3 dB of digital volume on foobar (because of a slight increase at ~80 hz that goes above the 0 line - just to be sure theres no clipping. perhaps unnecessary, but im not an expert, and this is my way of taking precautions), i was at ~11-12 oclock on the volume. 
i wasnt sure if unity gain would still be sufficient for the dt 770s, so i wanted to keep the option for having 2.5x, just in case, in order to still be able to use the 770s when i wanted to. now that i see unity gain is enough for them, this point is moot, but i had no way of knowing at the time.
 
when portable, i use iems streight from my phone. the O2, together with the Odac stay at home. i have no need for 6.5x gain at the moment, and as im starting college in june, i doubt very much ill be purchasing any new headphones in the next 4 years, and even if i do, it will probably be mad dogs, who dont need THAT much amplification, so i think im safe.
in fact, seeing as an odac is my source, i doubt ill need more than 2.5x gain for any future headphone, as i dont intend on getting any planar magnetics (except perhaps the mad dogs), or any "hard to drive" cans. 
 
edit: i wasnt encouraging anyone to do anything, i was simply thanking the participants of this thread that helped me understand which resistors to "clip" and assured me i wouldnt kill the amp while doing it. 

 

[mikeaj]

Quote:

hey all, quick question in regards to the O2. So i know the typical one is bought at JDS or some other such similar retailer. But while on eBay i stumbbled aross this. At $127 its a fair deal cheaper than its JDS counter part. I was curious, do you think there is any real SQ difference or build difference between the two? Anyone have any experience with this one? Thanks so much.

 
All the versions use the same PCB and same (or equivalent) parts.  The electric circuit is more or less almost identical, so you get almost identical performance.  The same enclosure is being used too, and it's fairly thick aluminum, though maybe not like you see on the expensive hi-fi gear.  All O2s are assembled and soldered by hand, no matter where they came from; there's always a chance of somebody making a sloppy joint or two, but that's not really a real concern to have.  As for the knobs and look of the front panel and so on, that's a matter of personal taste.
 
As mentioned earlier, Mayflower's just another builder out there, a good option if you want to save a bit of money.  On their website they have an even cheaper version that's missing the batteries—supply your own rechargeables, or just never use them as they're unnecessary if you keep the amp plugged in all the time.

 

[shadow419]

Clipping the input on the O2 isn't just about little more distortion using higher gain.  It sounds bad, really bad.  Having the volume pot in between the gain and output stage, instead of before the gain stage, is a design choice( or mistake depending on your view) the designer made.  When you don't have your gain set properly for your source voltage, and clip the input it sounds absolutely terrible.

 

[JakeJack_2008]

Thanx to all of You who advised me not to buy those fancy USB cables.
 
I've got the following question.
What should be a minimal distance between the ODAC & O2 and my laptop to avoid the USB-related  EMI/RFI?
(The USB cable - with the bottleneck  - which came from JDS Labs is 3 feet long.)
For instance, is it safe to use a 6-inch USB cable?

 

[mikeaj]

USB-related EMI?  If it's conducted in, then the length probably doesn't matter much.  If it's radiated in, I guess the ferrite bead could help?  The PCBs and internal electronics of the O2 and ODAC don't seem less prone to EMI issues than some others, supposedly.  I'm really not versed in boards, EMC, analog electronics, etc.  Maybe somebody else knows better.
 
Anyway, it's probably nothing to worry or even think about.  Try it and see.  If there were problems, you'd get something like hiss, hum, weird background sounds, etc., and not anything subtle like slightly skewing the balance or most aspects of sound quality.  So if you don't hear a problem, you probably don't need to think about it.  I think most people are better off using whatever works comfortably and dropping all the small audiophile misgivings and OCD tweakery concerns (not saying you're in that category, but I just don't think it's worth the energy in general, especially without any definitive testing to settle things once and for all).

 

[autoteleology]

I would say to just not worry about it unless it ends up being clearly audible and present. Worrying about tiny technical details that virtually never come into play is only going to interfere with your music enjoyment, probably even more so than the actual problems discussed could if they occurred.

 

[adydula]

One thing that keeps amazing me with the O2 is all the times I have adjusted the volume pot I never have once every heard an noise, clicks, pops or ticks...totally silent.
 
The background in silent....its the simple things...
 
Tom....lots of things bug me as well on these forums, lots of just plain silly'ness....but I don't get to hung up over it anymore...just not worth it.
 
I agree about its all 1's and 0's...and the use of a shielded cable...
 
I have used unshielded interconnects and a person I really respect told me I was asking for trouble.....I still have them but don't use them.
 
 
Alex

 

[thecansmancan]

Quote:

One thing that keeps amazing me with the O2 is all the times I have adjusted the volume pot I never have once every heard an noise, clicks, pops or ticks...totally silent.
 
The background in silent....its the simple things...
 
Tom....lots of things bug me as well on these forums, lots of just plain silly'ness....but I don't get to hung up over it anymore...just not worth it.
 
I agree about its all 1's and 0's...and the use of a shielded cable...
 
I have used unshielded interconnects and a person I really respect told me I was asking for trouble.....I still have them but don't use them.
 
 
Alex

Agreed, there is a lot of headphone jargon you have to wade through on here. Don't let it weight you down. Let us not forget, its all about the music and unless something is preventing you from enjoying it well then its and old case of "if it ain't broke, don't fix it."

 

[Shazb0t]

I'm looking for a short 3.5mm male to 3.5mm female cable that I can use so I don't have to keep unplugging and plugging in different headphones into the port on the o2.  I couldn't find one at some local stores or on monoprice, only long extension cables.  Is there a place that sells something short for this purpose?

 

[ProTofik]

Maybe you can get these to, or something similar:
 
Link 1
Link 2
 
I don't think you will find short 3.5mm to 3.5mm cable.

 

[mikeaj]

You could make one I guess, but you wouldn't be asking if you had the materials and desire to do that.

The really short stuff is usually M/M, intended for plugging in source to amp. There are quite a few options. e.g. FiiO L2 and L8, cheaper ones too

You could add a M/F 3.5mm adapter to that, which would be another inch and a half, or however long those are.

 

[Currawong]

You could simply buy a headphone double-adaptor.