Battou62
100+ Head-Fier
- Joined
- Mar 6, 2011
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Quote:
inb4 moved to SS
What is really impressive about this clairvoyant post is that it was post number 1337
inb4 moved to SS
I received my JDS Labs O2. I am using it with K501 and NuForce uDAC. I hear some distortion. Is it because of DAC or amp?
Try using the lower gain setting, if you are not already doing so. Also, the NuForce uDAC(2) is not very good in terms of distortion, and it cannot output a full scale signal without clipping. In this particular aspect, even a decent onboard audio chip is better.
Originally Posted by Willakan /img/forum/go_quote.gif
I think that people are reading too much into opamp rolling. Opamp rolling works on two principles:
1) That you know better than the designer/designer cut corners of some sort.
Originally Posted by Willakan /img/forum/go_quote.gif
There are engineers that believe lots of things. None of these things have ever been produced under controlled conditions. I wonder why.
I'm pretty sure modding the Fostex T50RP works on this principle, yes? In the case of the O2 corners were cut from a price perspective, if not, it'd be 'spec'd out' with AD8620, or the like...
Just a quick question so I wont have to read trough 90 pages... is this O2 really that good if I just want a powerful amp to amplify whats coming from the DAC with colorations, but with lots of authority and power? Would it be an improvement over the Little Dot Mk5 for AKG Q701's?
Yes, but maybe or maybe not by a significant or even audible amount. If you go by the spec listed for the Little Dot Mk5, it claims 0.05% THD+N into 300 ohms at 100mW (5.48V rms) with the standard 1 kHz test tone. Assuming that the O2 does similarly with 300 ohms as it does with 150 ohms and 600 ohms (a very reasonable assumption, considering the performance into 150 ohms and 600 ohms is very similar), it gets about 0.001% THD+N with the same test. It depends on the design, but most amplifiers will have a harder time putting the same amount of power into a lower impedance like the ~60 ohms of the Q701, so the distortion could well be significantly higher than 0.05% just for THD+N when driving the Q701. With real music, distortion is higher than for just a 1 kHz test tone, because of intermodulation products and so on.
100mW is actually a typical power input to a Q701 to play loudly, so that's not that much of a stretch. Into a load like that, O2 should get between 0.001 and 0.002% THD+N...for what that's worth. THD+N for a 1kHz input is just one benchmark out of many, so it's not particularly indicative of total performance, especially since the number alone doesn't tell you about whether the distortion is 3rd order harmonics, 2nd order, or what else. Many more tests are on the designer's blog for the O2, if you want to look yourself.
They don't list the output impedance for the Little Dot, but based on the listed output power at different loads, it would seem like it's probably not negligible. That would slightly alter the frequency response of those headphones and contribute to additional distortion when driving headphones as opposed to test resistors on the lab bench. Still, we have a very incomplete picture of the type of distortion and the overall performance characteristics of the Little Dot, so it's hard to say if these issues would actually be audibly worse and whether the O2 would actually be a real upgrade for those headphones. By the books, the specs indicate lower performance for the Little Dot, but the "how much" and "how" are not clear.
Are we forbidden to mention that blog or simply forbidden to link to it?