HD800 is super easy to power when you place it next to the HE6.
I wasn't talking about powering the HD800 but to find a proper amp (coloration, etc). But I want pure FIDELITY so the O2/ODAC is the perfect choice for me if I ever buy an HD800 again.
HD800 is super easy to power when you place it next to the HE6.
I think if I ever do buy another pair of expensive headphones it'll be the HD 800. I'm a bit concerned that they'd be overly bright compared to the HD 650. Reports do seem to suggest that to be the case. I also might need to buy another amp which I'd be loathe to do.
This is my Mayflower O2+ODAC. I just put in a couple of hours of listening last night, using it to drive the 90 dB/mW Hifiman HE-560. I was satisfied at the 3-4 o'clock position on the volume knob, and I listen loud.
For exceptionally quiet tracks, the volume may have to be turned up higher.
How does it sound? Like the track being played through the sound signature of the headphone. Bass is present and has impact.
A tip for driving less sensitive headphones (90 dB/mW range): The gain settings have to be optimized.
The common mistake when trying to drive a less sensitive headphone with the O2 is to switch to high gain, and if the source output voltage exceeds a certain amount (see below), and the amp is going to clip and sound harsh or broken.
To get the most output on AC power (which is the only option for an O2+ODAC anyway), 7 divided by the output of your source is the optimum gain. If the number exceeds 7, it's going to clip eventually as the volume gets turned up. For example:
FiiO X5 - 1.5 V output, the optimum gain on the O2 would be 7/1.5=4.6666 which translates to a practical gain of 4 or 4.5.
Most DACs output at 2V, so 7/2 = 3.5 optimal gain.
The default gain settings for 2.5 and 6.5 were made to account for both battery and AC usage with a variety of source input voltages:
2-2.5V desktop DACs (use 2.5 gain)
.5-.7V portable sources (use 6.5 gain)
This is to the best of my understanding. Hopefully JDS or Mayflower will let me know if something isn't right.
Hope this helps!
Yup, the high gain setting is not for low sensitivity headphones, but rather for quiet sources using the line in. Using the high gain with the ODAC will clip if your source is also set to maximum volume and you are listening to a song that is close to the max level. Given that I only need to be at the 3 O'clock position with both my HD600s and K702's I can't imagine what would ever need more than 50% of the ODAC's output (unless you are listening to some incredibly quiet high DR stuff).
Yup, the high gain setting is not for low sensitivity headphones, but rather for quiet sources using the line in. Using the high gain with the ODAC will clip if your source is also set to maximum volume and you are listening to a song that is close to the max level. Given that I only need to be at the 3 O'clock position with both my HD600s and K702's I can't imagine what would ever need more than 50% of the ODAC's output (unless you are listening to some incredibly quiet high DR stuff).
The 6.5x gain was there for sources with 1 Vrms (on AC power) or below. 2.5x for anything else up to around 2.5 Vrms. This is to accomodate a wide range of sources. I believe most of the complaint about O2 clipping and not sounding right is due to source/gain mismatch.
I have a DX90 @ 1.7 Vrms and O2 at 2.5x gain drives my T1 very well with the volume knob between 1 to 3 o'clock position.
I have an O2+ODAC coming from JDS Labs with 1x and 3.5x gain. HE-6 is not of my wish list so I got myself covered on the DAC/Amp part for a long time. I hope
not a surprise really. more than half the people I talk to that are already into audio, so more than half of a very precise population target, have no clue about how to use gain settings and go with the usual moaaaarrrrr is better idea that leads to really messed up things. like clipping when it shouldn't, or people crying over the very huge channel imbalance while using sensitive IEMs on high gain or simply the fact that the volume level is harder to set...
I'm very sure a lot of the dissatisfied users with the O2 were themselves the cause of the problem. that and those who expect an amp to sound "different". those guys will never like anything transparent obviously.
I think that having the X1 gain is a good start for 90% of headphones/IEMs. then 2.5 or 6times the gain should be picked in accordance to our harder to drive headphone.
that way I see very little reason to be dissatisfied.
To get the most output on AC power (which is the only option for an O2+ODAC anyway), 7 divided by the output of your source is the optimum gain. If the number exceeds 7, it's going to clip eventually as the volume gets turned up. For example:
FiiO X5 - 1.5 V output, the optimum gain on the O2 would be 7/1.5=4.6666 which translates to a practical gain of 4 or 4.5.
Most DACs output at 2V, so 7/2 = 3.5 optimal gain.
The default gain settings for 2.5 and 6.5 were made to account for both battery and AC usage with a variety of source input voltages:
2-2.5V desktop DACs (use 2.5 gain)
.5-.7V portable sources (use 6.5 gain)
This is to the best of my understanding. Hopefully JDS or Mayflower will let me know if something isn't right.
Hope this helps!
The common mistake when trying to drive a less sensitive headphone with the O2 is to switch to high gain, and if the source output voltage exceeds a certain amount (see below), and the amp is going to clip and sound harsh or broken.
To get the most output on AC power (which is the only option for an O2+ODAC anyway), 7 divided by the output of your source is the optimum gain. If the number exceeds 7, it's going to clip eventually as the volume gets turned up. For example:
FiiO X5 - 1.5 V output, the optimum gain on the O2 would be 7/1.5=4.6666 which translates to a practical gain of 4 or 4.5.
Most DACs output at 2V, so 7/2 = 3.5 optimal gain.
The default gain settings for 2.5 and 6.5 were made to account for both battery and AC usage with a variety of source input voltages:
2-2.5V desktop DACs (use 2.5 gain)
.5-.7V portable sources (use 6.5 gain)
This is to the best of my understanding. Hopefully JDS or Mayflower will let me know if something isn't right.
Hope this helps!
Best summary I've seen in a long time.
Default gain of our custom O2+ODACs is 1.0/3.5x, which is optimal as long as the O2+ODAC is driven by its own DAC. It makes sense to increase gain only if you plan to listen from from a weaker external source, or if the majority of your music is recorded well below 0dB.
Best summary I've seen in a long time.
Default gain of our custom O2+ODACs is 1.0/3.5x, which is optimal as long as the O2+ODAC is driven by its own DAC. It makes sense to increase gain only if you plan to listen from from a weaker external source, or if the majority of your music is recorded well below 0dB.
Actually, this is a bit confusing. The O2 has very unusual clipping behavior and clips *only* based on the level of the input. The O2's volume control has no effect at all on clipping behavior.
I wonder if anyone ever tried to replicate the measures posted online in terms of power output.
One thing which struck me, is how an amp rated for 630+mW on 33 ohms, which would require over 130mA of RMS (assuming power figures in the most noted web sites are RMS) current, would work with the original NJM4556AD current stage opamp, which is rated at 70mA peak.
We've replicated every test and verified each specification by published NwAvGuy on Objective2 and ODAC. All measurements are legitimate, if not slightly conservative.
Objective2 uses two, parallel NJM4556 ICs per channel. Available current handling is doubled to 2*70 = 140mA.
We've replicated every test and verified each specification by published NwAvGuy on Objective2 and ODAC. All measurements are legitimate, if not slightly conservative.
Objective2 uses two, parallel NJM4556 ICs per channel. Available current handling is doubled to 2*70 = 140mA.
I see, thanks. I finally been able to find a schematic which is bigger than 200x200 pixels
So it is 630mW peak on 33 ohms, right?
Hello there John.
Is there a plan to make a much more portable O2? Is that even possible with the license and present design?
Also, is there an existing portable amp out there whose design is based or similar to the O2 and ODAC?
Cheers.