[kyoshiro]

we could probably make it a riser card and just get a bigger enclosure while still having the batteries in place.

 

[kiertijai]

I apologize if this question has been asked,  I have followed this thread for some time
and would like to know the performance of O2 amplifier comparing to the AMB mini3 amplifier

 

[stv014]

Quote:

I apologize if this question has been asked,  I have followed this thread for some time
and would like to know the performance of O2 amplifier comparing to the AMB mini3 amplifier

 
These measurements are from the NwAvGuy site.
 

[size=small]Measurement[/size]	FiiO E11	[size=small]O2[/size]	[size=small]FiiO E9[/size]	[size=small]AMB Mini3[/size]
[size=small]Frequency Response[/size]	+/- 0.1 dB A	[size=small]+/- 0.1 dB A[/size]	[size=small]+/- 0.1 dB A[/size]	[size=small]+/- 0.1 dB A[/size]
[size=small]THD 1 Khz 150 Ohms[/size]	0.004% A	[size=small]0.0016% A[/size]	[size=small]0.005% A[/size]	[size=small]0.002% A[/size]
[size=small]THD 1 Khz 15 Ohms[/size]	0.011% B	[size=small]0.0023% A[/size]	[size=small]0.037% C[/size]	[size=small]0.017% B[/size]
[size=small]THD 20 hz 15 Ohms[/size]	0.017% B	[size=small]0.0023% A[/size]	[size=small]0.05% Good[/size]	[size=small]0.01% B[/size]
[size=small]THD 20 Khz 15 Ohms[/size]	0.011% B	[size=small]0.010% A[/size]	[size=small]0.003% A[/size]	[size=small]0.45% F[/size]
[size=small]IMD CCIF 15 Ohms[/size]	0.002% A	[size=small]0.001% A[/size]	[size=small]0.05% C[/size]	[size=small]0.043% D[/size]
[size=small]IMD SMPTE[/size]	0.0079% A	[size=small]0.002% A[/size]	[size=small]0.002% A[/size]	[size=small]0.009% B[/size]
[size=small]Noise A-Wtd[/size]	-101.3 dBu B	[size=small]-114 dBu A[/size]	[size=small]-94.7 dBu C[/size]	[size=small]-103.2 dBu B[/size]
[size=small]Max Output 15 Ohms[/size]	63 mW B	[size=small]337 mW A[/size]	[size=small]1067 mW A[/size]	[size=small]104 mW A[/size]
[size=small]Max Output 33 Ohms[/size]	101 mW C	[size=small]613 mW A[/size]	[size=small]883 mW A[/size]	[size=small]98 mW C[/size]
[size=small]Max Output 150 Ohms[/size]	52 mW C	[size=small]355 mW A[/size]	[size=small]317 mW A[/size]	[size=small]38 mW C[/size]
[size=small]Output Impedance[/size]	0.5 Ohms A	[size=small]0.54 Ohms A[/size]	[size=small]10 Ohms C[/size]	[size=small]0.9 Ohms A[/size]
[size=small]Crosstalk 15 Ohms[/size]	48 dB B	[size=small]65 dB A[/size]	[size=small]63 dB A[/size]	[size=small]40 dB C[/size]
[size=small]Channel Balance[/size]	1.1 dB B	[size=small]0.6 dB A[/size]	[size=small]1.8 dB C[/size]	[size=small]1.14 dB B[/size]
Battery Life	~10 hours	~8 hrs / ~30 hrs	AC Only	~5 hours

 
Note: the maximum power of the O2 is specified for AC operation. When using batteries, the power output into 150 Ohms is reduced to 180-200 mW (depending on the battery voltage); the 15 and 33 Ohm maximum power values do not change as much, because these are current limited.
 

 

[kiertijai]

@stv014,   thanks so much for the info.
soundwise which is better? or which genre of music the O2 or mini3 are more appropriate
it seems like the O2 has more driving power so it can drive more difficult headphone, I think
it should be able to drive the HD800, LCD2 , T1   but it may not be able to drive the HE6, is that correct?

 

[mikeaj]

Right, O2 is larger and heavier, and part of that is because of using two 8.4V batteries rather than one like the Mini3 uses.  They're not really comparable in that sense.  So of course the O2 can output more power.
 
People report using HD 800, LCD2, T1, etc. with O2, and this can also be told by looking at the measurements at InnerFidelity.  Check out the data sheets and the power needed to reach 90 dB SPL and the impedance for a given headphone.  You need 100 times more power to reach 110 dB SPL as compared to 90 dB SPL, and 110 dB SPL peaks is about as loud as most people will listen for very quiet music with a lot of dynamic range (some may listen a little bit louder than that).  e.g. if headphones are 33 ohms and need 2 mW for 90 dB SPL, they will need 200 mW for 110 dB SPL so the O2 and E9 and many others can do, but some smaller portable amps may not be able to do.
 
For those kinds of volumes, HE-6 needs more power than something like O2 can provide.

 

[wje]

Quote:

Hey Wayne,  be sure to measure the voltage out of your new adapter because 13 volt might not be enough.
 
Nwavguy explain it in the "Using the O2, Power jack" section. The O2 expect at least 14 volts and not more then 20. The 12 volt 200 mah from the BOM is actually putting out about 14 volts as per NwAvGuy. Also it need at least 200 mah min.
 
To be safe I went with the 16 volts 400 mah like many other did.

Being that my current Radio Shack adapter is within my 30-day return windown and tops out at a 13V AC setting, I think I'm going to exchange it today for their next level up model - the one that can do 18V or 22V AC.  I'll keep it on the 18V AC setting.  It's also capable of delivering 1,000mA, if required. 
 
 

 

[Willakan]

 
Quote:

@stv014,   thanks so much for the info.
soundwise which is better? or which genre of music the O2 or mini3 are more appropriate
 

The O2 reproduces the input signal, but louder, with no perceivable colouration. It is your headphones which will decide the appropriateness of your setup for different genres.

 

[sonitus mirus]

 
Just received my JDS Labs-built O2 last night.  I plan on using this amp to replace my Headroom Micro Amp that I am currently using in my office.  I already yanked the batteries out, as I am only going to use this with AC power anyway.
 
The build quality is generally very good, however, after pulling out the batteries, I noticed that a leg of the through hole resistor on the back left of the PCB (when viewed from the front) was extremely close to  the fastening screw for the back panel.  I just left that screw out to be safe, as I did not want to short the resister to the case.
 
It runs cool, and it sounds good with my typical source of 320 mp3 (MOG) or Q9 Ogg Vorbis (Spotify) subscription music service tracks from my Squeezebox Touch.  I have been using the SB's internal DAC, which does a fairly good job for the source quality being used, but I'm not able to keep the volume at a fixed level (100%) like I was with my Micro Amp using the low gain setting.  The O2 amp is simply way too loud for my ears using the easy-to-drive ATH-M50s (38Ω 99dB) without significantly lowering the volume on the SB Touch. 
 
I have been on a quest for new headphones to use at work, and I suppose that I will have to make sure these are not overly efficient.  I need a closed design at work, and I know the Denon's do not isolate enough (have D5000's), and I did not prefer the Beyer DT-770 (250Ω) over the M50s on a 2 week trial a few weeks back.  The Fischer Audio 003 is what I want to try, but they are impossible to find in stock from any site I feel comfortable with making a purchase.  I looked into the AKG K550, but AKG does not have the bass impact I crave.
 
Anyway, the O2 is an amp, and it shouldn't change the sound, just make it louder.  That said, there are 2 things that I noticed in my very short audition between my Micro Amp and the O2.  I seem to enjoy the classic rock genre more with the O2 setup.  I used the crossfeed with the Micro Amp, so that may be the difference I believe I hear.  Also, the lower frequencies with the O2 seem to cut off more immediately, without as much resonance, if that makes any sense.  Listening to a BASS-heavy track from Deadmau5, when there is no bass present, it is absolutely gone with the O2, but with the Micro Amp, each deep note seemed to carry over a bit more into the next.  It appeared to be a tad bit sloppier before, where it sounds more precise now. 
 
These are all very small differences that I probably cannot possibly notice outside my own imagination, and I have no way to properly ABX anything in my office.  Just going by the objective numbers, and having listened for a while now, I am keeping the O2 in my office and retiring the Micro Amp for now.
 
 
 
 

 

[maverickronin]

Quote:

I have been on a quest for new headphones to use at work, and I suppose that I will have to make sure these are not overly efficient.  I need a closed design at work, and I know the Denon's do not isolate enough (have D5000's), and I did not prefer the Beyer DT-770 (250Ω) over the M50s on a 2 week trial a few weeks back.  The Fischer Audio 003 is what I want to try, but they are impossible to find in stock from any site I feel comfortable with making a purchase.  I looked into the AKG K550, but AKG does not have the bass impact I crave.

 
The Audio Technica W1000x are probably worth a look.  They don't have a ton of isolation but they sure beat the Denons in that area.  If you're up for a little DIY modded T50RPs sound really great too.

 

[mikeaj]

 
Quote:

It runs cool, and it sounds good with my typical source of 320 mp3 (MOG) or Q9 Ogg Vorbis (Spotify) subscription music service tracks from my Squeezebox Touch.  I have been using the SB's internal DAC, which does a fairly good job for the source quality being used, but I'm not able to keep the volume at a fixed level (100%) like I was with my Micro Amp using the low gain setting.  The O2 amp is simply way too loud for my ears using the easy-to-drive ATH-M50s (38Ω 99dB) without significantly lowering the volume on the SB Touch. 
 
I have been on a quest for new headphones to use at work, and I suppose that I will have to make sure these are not overly efficient.

 
Consider opening up the case and removing (snipping out) R19 and R23, which are around the gain switch area.  You needn't actually desolder them, just break the connection.  The leads are thin, so this is not difficult:

 
That will drop the high gain setting (switch in) from 6.5x to 1x.  The low gain is default at 2.5x.  This should help with the volume being too high.

 

[Willakan]

The JDS Labs front panel looks very nice: if I have need of another O2 I'll think I'll cough up as opposed to DIYing it.
I wouldn't bother with keeping the screw out: the proximity of the screw thread and the resistor lead is a known potential issue and JDS Labs have excellent quality control AFAIK, so the lead will have been clipped so it can never quite come into contact.
 
+1 on clipping the High Gain setting resistors: you couldn't use high gain with the Squeezebox Touch anyway, as its 2.06V outputs would result in the input stage clipping (high gain is just for MP3 players and low-voltage sources rather than more volume). The O2 makes a lovely unity-gain buffer, and if you ever need more volume it's just a button press away.

 

[sonitus mirus]

Great information, and I will consider it.  I have found that it is easier to adjust the volume with the Squeezebox.  The screen is always on anyway when the music is playing, and there is no mechanical movement and wear over time as there would be using the amp's volume knob.  I like good sound quality, but I am certainly not going for critical listening.  The only thing I don't like is having to re-adjust the amp volume when I shut it off and back on, as I normally turn the volume all the way down before shutting off an amp or removing the headphones.  I'll get used to it, I'm sure.
 
Thanks again!

 

[Twinster]

+1 on removing (cutting) the High gain resistors. I got mine set with 1x & 3x. As for a good set of headphone for work I personnaly use the Beyerdynamic DT1350 but also eyeing the Sony MDR-Z1000 if you don't mind on-ear headphone.
 
For Fisher Audio Headphone try Dimitri. He will take care of you. 

 
 
[size=medium] Dimitri Trush 
President/Manager,  
Musica Acoustics 
trush@musicaacoustics.com
tel +81 422 38-7452
fax +81(0)422-38-7457
skype: musicaacoustics
www.musicaacoustics.com
www.musicaacoustics.jp
[/size]
[size=medium]

[/size]


Quote:

 
Just received my JDS Labs-built O2 last night.  I plan on using this amp to replace my Headroom Micro Amp that I am currently using in my office.  I already yanked the batteries out, as I am only going to use this with AC power anyway.
 
The build quality is generally very good, however, after pulling out the batteries, I noticed that a leg of the through hole resistor on the back left of the PCB (when viewed from the front) was extremely close to  the fastening screw for the back panel.  I just left that screw out to be safe, as I did not want to short the resister to the case.
 
It runs cool, and it sounds good with my typical source of 320 mp3 (MOG) or Q9 Ogg Vorbis (Spotify) subscription music service tracks from my Squeezebox Touch.  I have been using the SB's internal DAC, which does a fairly good job for the source quality being used, but I'm not able to keep the volume at a fixed level (100%) like I was with my Micro Amp using the low gain setting.  The O2 amp is simply way too loud for my ears using the easy-to-drive ATH-M50s (38Ω 99dB) without significantly lowering the volume on the SB Touch. 
 
I have been on a quest for new headphones to use at work, and I suppose that I will have to make sure these are not overly efficient.  I need a closed design at work, and I know the Denon's do not isolate enough (have D5000's), and I did not prefer the Beyer DT-770 (250Ω) over the M50s on a 2 week trial a few weeks back.  The Fischer Audio 003 is what I want to try, but they are impossible to find in stock from any site I feel comfortable with making a purchase.  I looked into the AKG K550, but AKG does not have the bass impact I crave.
 
Anyway, the O2 is an amp, and it shouldn't change the sound, just make it louder.  That said, there are 2 things that I noticed in my very short audition between my Micro Amp and the O2.  I seem to enjoy the classic rock genre more with the O2 setup.  I used the crossfeed with the Micro Amp, so that may be the difference I believe I hear.  Also, the lower frequencies with the O2 seem to cut off more immediately, without as much resonance, if that makes any sense.  Listening to a BASS-heavy track from Deadmau5, when there is no bass present, it is absolutely gone with the O2, but with the Micro Amp, each deep note seemed to carry over a bit more into the next.  It appeared to be a tad bit sloppier before, where it sounds more precise now. 
 
These are all very small differences that I probably cannot possibly notice outside my own imagination, and I have no way to properly ABX anything in my office.  Just going by the objective numbers, and having listened for a while now, I am keeping the O2 in my office and retiring the Micro Amp for now.
 
 
 
 

 

 

[DarknightDK]

Quote:

Also, the lower frequencies with the O2 seem to cut off more immediately, without as much resonance, if that makes any sense.  Listening to a BASS-heavy track from Deadmau5, when there is no bass present, it is absolutely gone with the O2, but with the Micro Amp, each deep note seemed to carry over a bit more into the next.  It appeared to be a tad bit sloppier before, where it sounds more precise now. 
 
These are all very small differences that I probably cannot possibly notice outside my own imagination, and I have no way to properly ABX anything in my office.  Just going by the objective numbers, and having listened for a while now, I am keeping the O2 in my office and retiring the Micro Amp for now.
 

These are my observation of the O2 as well. The bass does not go as deep, but very tight and punchy. There is not much extension of lower bass notes. Hope this changes after burn-in (right now its probably sitting at 40 hours). However, the O2 is very enjoyable with great PRaT. Will post more impressions of the O2 after some extensive listening.
 

 

[stv014]

Quote:

There is not much extension of lower bass notes.

 
It does not seem to lack extension (due to the low output impedance, it should stay flat enough with a headphone load as well), the roll-off is insignificant at audible frequencies. Although more bass is not added, either.