[439598]

Isnt the other function of those caps to reserve power for the amp?

once I have a replacement mc7912 ill record the output to see if theres any difference, and compare to digital waveform to see which is more accurate.

 

[JakeJack_2008]

No, the difference is unlikely to be noticed except under extreme conditions.

Thank you very much.
So, certainly teenagers with or without golden ears, or even audiophiles, would not hear any difference.

By the way, I have forgotten to mention my setup:
laptop (Windows 10) ----> ODAC ----> O2 ----> Beyerdynamic DT 880 (250 Ohm)



On another matter.
Last week I did replace two Tenergy 9V batteries in my JDS Labs O2 (Feb. 2013) amp.
I suppose that those batteries were installed by JDS Labs in late 2012 or early 2013.
After more than 5 (five) years of usage, the old batteries did not leak, were not corroded or rusty, etc.
and above all, surprisingly still performed 'quite' well.
Outside, the old batteries looked like new - very clean. Obviously I don't know how they changed inside,
over the period of 5 years .

 

[Zouka]

Has anyone upgraded from this to something else and found it to be a worthy upgrade?

I've been using the ODAC/O2 for years now and since I will be getting a Focal Clear soon I think I'm up for a DAC upgrade too.

 

[BenF]

Has anyone upgraded from this to something else and found it to be a worthy upgrade?

I've been using the ODAC/O2 for years now and since I will be getting a Focal Clear soon I think I'm up for a DAC upgrade too.

Oppo HA-2/HA-2SE has a DAC that sounds better to me.
I liked it with Elear, TH900MK2 and AB-1266.
O2 is unsurpassable though.

 

[Arkady Duntov]

I've been using the ODAC/O2 for years now and since I will be getting a Focal Clear soon I think I'm up for a DAC upgrade too.

May I ask why you find the ODAC to be insufficient?

 

[WilliamLeonhart]

I would say the m9xx, the Mojo or the iDSD Micro. Those were the first that proved to me the O2 ODAC wasn’t everything. What I remember was cleaner, overally more detailed sound, especially in the trebles. Also no more problems with ASIO buffers. That being said, these were still my first “proper” amp/DAC and I’m still using the ODAC for my computer speakers.

 

[raoultrifan]

I have the ODAC A revision, the first one and it's the noisiest from all the DACs I have. Not that I can actually hear that noise while listening to regular music, but when I get my O2 at max. gain and full volume (no music playing!) I can hear the noise with 16-ohms IEMs, but also with AKG K550 and Beats Solo2. In order of background noise from highest-to-lowest from the RCA output I got this: ODAC > ROLAND UA-M10 > ASUS Essence One MKii Muses > BURSON PLAY = ASUS U7 (Essence One and PLAY are heavily modded; U7 has a much lower output volume, so not the best way to compare it with the other DACs).

Also, my ODAC rev. A has a lot of noise around 500kHz, inaudible of course, but I don't care...it's still there and it shouldn't be. I strongly suggest you to get the ODAC rev. B or the OL version or the SDAC, so don't buy the ODAC rev. A.

 

[WilliamLeonhart]

I have the ODAC A revision, the first one and it's the noisiest from all the DACs I have. Not that I can actually hear that noise while listening to regular music, but when I get my O2 at max. gain and full volume (no music playing!) I can hear the noise with 16-ohms IEMs, but also with AKG K550 and Beats Solo2. In order of background noise from highest-to-lowest from the RCA output I got this: ODAC > ROLAND UA-M10 > ASUS Essence One MKii Muses > BURSON PLAY = ASUS U7 (Essence One and PLAY are heavily modded; U7 has a much lower output volume, so not the best way to compare it with the other DACs).

Also, my ODAC rev. A has a lot of noise around 500kHz, inaudible of course, but I don't care...it's still there and it shouldn't be. I strongly suggest you to get the ODAC rev. B or the OL version or the SDAC, so don't buy the ODAC rev. A.

That's right, the revB is much more refined.

It should also be noted that some O2 does suffer from clipping at high gains. I owned 3 different versions of it and the 2nd one, made by Mayflower, had that issue at 3.5x. Obviously 1.5x was more than enough for every headphones I used with the O2.

 

[raoultrifan]

I know about the clipping and this is occurring only when feeding it with loud music. Swapping the NJM2068 with a different op-amp might help a bit, though the output stage will start clipping soon as well. Everything is documented on O2's building "datasheet" and measurements. However, I still find it the cleanest amp I've ever heard and completely flat.

 

[MrMateoHead]

I know about the clipping and this is occurring only when feeding it with loud music. Swapping the NJM2068 with a different op-amp might help a bit, though the output stage will start clipping soon as well. Everything is documented on O2's building "datasheet" and measurements. However, I still find it the cleanest amp I've ever heard and completely flat.

Not to be defensive or anything, but are you sure the clipping your hear is from the O2 / ODAC and not the recording itself? The combo has always been revealing enough to make recorded clipping audible through a pair of sensitive headphones (like planars). Tons of my music, whether CD or not, clips. It is often audible if I listen for it. Like Beck, attached. I don't hate Mp3s because they "sound bad" - I hate them because when the album has no headroom Mp3s will push near-clipping into clipping. And then consumers PAY for it!

I don't think I ever heard noise from my ODAC that wasn't in the end indicative of a failed / failing ODAC unit. The Rev B is supposedly more reliable, I'm sure it sounds great.

 

[castleofargh]

Not to be defensive or anything, but are you sure the clipping your hear is from the O2 / ODAC and not the recording itself? The combo has always been revealing enough to make recorded clipping audible through a pair of sensitive headphones (like planars). Tons of my music, whether CD or not, clips. It is often audible if I listen for it. Like Beck, attached. I don't hate Mp3s because they "sound bad" - I hate them because when the album has no headroom Mp3s will push near-clipping into clipping. And then consumers PAY for it!

I don't think I ever heard noise from my ODAC that wasn't in the end indicative of a failed / failing ODAC unit. The Rev B is supposedly more reliable, I'm sure it sounds great.

it's a matter of signal input. originally the gain switch was for when the source was a super weak portable device with a line out at sometimes not even 0.5V. so you would multiply that by 3 or 6 with the gain setting and still be well within the maximum voltage the amp can output into whatever load. 6*0.5V that's 3V. of course the O2 can deal with that.
but if you have a DAC sending a signal at 2 or 3V and you still ask the amp to multiply that value by 3 or 6 times, now we might get in trouble. ^_^

but it was never intended in the design to use high gain and high voltage input at the same time. that just ends up being a misuse of a function for weak lines out.

 

[raoultrifan]

I think WilliamLeonhart was referring to the distortions made by high-gain use for the VAS opamp, NJM2068. This has been explained by the designer, so it's a limitation that can be resolved by using a NE5532, LM4562 or a similar opamp. However, for most of us a max. gain between 3-3.5X will suffice, so I don't really see this as being a limitation, but more a...specification.

Like I said it for several times, O2 is a great amplifier and given the very low noise and flat bandwidth I consider it a reference amplifier. I'm using the OPA1652 in VAS for now with MUSES8920 in output buffer and I'm enjoying every second of music out of it.

 

[WilliamLeonhart]

Did you hear a difference in sound signature when rolling op-amp though? I had both the 8920 and 8820 and I couldn’t hear any difference compared to the NJM at all. The Burson and the Sparko brought about just a tiny bit of change (could be my imagination). So I think nwAV didn’t design the O2 for opamp rolling. On the cMoy or the Burson Play for example, you’d hear it right away

 

[raoultrifan]

No, couldn't fell anything, after all it's damned flat line in bandwidth response (tested with sine and square wave signals).
The only advantage of the MUSES8920 in output stage would be lower DC-output, especially if you want to modify the high-pass filter (the trade-off resistor/cap). I think I posted some details and pics around this forum recently...just can't find this info now.

 

[439598]

got something new to try. I found replacing the 2068 for anything else never sounded right. The OPA1612 or LM49720/LM4562 preserve much more detail but they dont really sound good, its not obvious and you will probably like the extra detail at first (if you can hear it) but after a while its gets fatiguing. The best choice for U1 is actually nothing at all. with some solid core copper either link the input and outputs of the U1's socket or get a new turned pin socket and link the input and outputs pins and use that to 'roll' this little adapter like an op amp (dont link the power rails by accident, check the pinout carefully).

This removes all gain options. its more neutral and accurate than any op amp, the volume was slightly lower compared to 1X gain with an op amp. it was the complete opposite experience to rolling op amps, it sounded flat and boring at first, i was used to the subtle colouration of the op amps, but it just keeps growing on me.

for output stage the OPA1612 is untouchable, I have been listening for weeks now comparing over and over and Im totalyl confident in this. if you think the current is an issue I bought an R2R11 and prefer the O2 amp with OPA1612 in 90% of the time. the OPA1612 is cutting edge with those distortion levels, discreet designs can not compare in neutrality and detail