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Post by dalethorn on Jan 27, 2012 18:38:03 GMT
The Objective2 is a small (4-1/4 x 3-1/4 x 1-1/8 inches excluding projections) headphone amp, normally sold as a kit I presume, by JDS Labs (designed by 'NwAvGuy'). It's a beautiful piece of gear and sounds very, very good. The first headphone I tried it with is a German Maestro 8.35D which is fairly efficient and 35 ohms, and with my strongest material it didn't distort even a little as far as I could hear. My ultimate test for dynamics, despite it not being the very best original recorded quality, is Jimmy Smith's Basin Street Blues (HDTracks FLAC format) where mass horn crescendos at 10 and 14 seconds into the track will stress-test any headphone and amp. I also have a Chesky FLAC track, Wonjung Kim - Girl From Guatemala, which has some major dynamics. That one played well. My stress-test tracks for bass are Afro Celt Sound System - Inion Daughter, Donald Fagen - Morph The Cat, and Pink Floyd - Speak To Me. The bass was as good as I've ever heard.
With this amp everything is on the front panel. AC input (see below), power switch, miniplug headphone output, LED power indicator, volume control, high/low gain switch, and miniplug line input. I'm using a genuine FiiO right-angle LOD cable to connect to Apple i-devices, and based on my experience using the Apple composite A/V cable with another headphone amp, I'd say the short (2-1/2 inch) FiiO cable does not compromise the sound quality.
One thing I haven't done is try to get to the batteries. I assumed I would be able to easily swap them and charge them externally, but it appears that the only way to do that is to remove the 4 screws on the back panel and then replace the batteries and the panel after the swap. Not very convenient. And there is a danger factor with this amp. All of the AC adapters I've ever had (and that's a lot!) are AC to DC, but this amp requires an AC to AC adapter to charge the internal batteries if you don't want to swap them as described.
Running tests with another headphone, the Sennheiser HD-800, I almost forgot how good that headphone sounds. A headphone this good shouldn't live in the closet, especially if you have a really good headphone amp to drive it with. The following are a few tracks I used for testing that will reveal various problems in headphones and amplifiers:
David Chesky/Wonjung Kim - Girl From Guatemala - 96k FLAC: The bass of the 800 often gets less than enthusiastic response from users. Listening with this amp - Mmmmm, good. It still won't satisfy most bass mavens, but if you're not a basshead, it's marvelous. The extreme highs here with very loud xylophone(?) impacts on the high notes are not only clean and clear, but the tonal colors are vibrant and detailed and you hear things that just get smeared or distorted etc. with less than a good quality headphone amp, or most run-of-the-mill headphones. Note: This a a very low-volume track even accounting for the huge dynamics, so I had to use maximum volume on low gain for a decent and fairly loud play. No problems at all. No background noise. So I took the kit into a central room in the house where I could close the door and shut out 99 percent of the daytime noise. Then I put the amp on high gain and ran the volume to maximum and still no amp noise. For just a second I hit 'play' to a music track and BLAST! - I turned that one down really fast! There is no noise apparently.
Cat Stevens - Morning Has Broken - CD rip to 320k CBR MP3: This is my main test for "How does it sound in general?", and everything was right. Balance, tone, everything.
Clark Terry - Sugar Blues - 96k FLAC: Another low-volume track played at maximum volume on low gain. The horn blasts here in the last parts of the track have a real edge to them. With this amp and the HD-800, the edges had a certain tonal quality. Does that seem like a peculiar thing to say? With the other headphone the edges were just edgy.
Scarlatti/Kipnis - Sonata in E - 96k FLAC: A very low-volume track played at maximum volume, on high gain this time. Lots of transient detail with the harpsichord's plucked strings - sounds really good.
Tony Bennett - I Left My Heart In San Francisco - CD rip to 320k MP3: This track's sibilants have sibilants, if you get what I mean. The sibilants have a life of their own, like echo effects that reverberate off into space somewhere. You probably can't say "Sssssssssssssss..." as strongly as the sibilants on this track. Yet they're not irritating played fairly loud, even if somewhat unmusical.
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chris1967
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Post by chris1967 on Jan 27, 2012 18:50:09 GMT
I got this amp from JDSlabs assembled...
It is absolutely fantastic, lots of power, and very very neutral clean sound. No exaggeration is any frequency...
I used it with all my phones and it is very happy even with my Q701's, at low gain,... i find it adequate for the Sennheiser HD800 with pot position at 11oclock for normal listening...(also on low gain)... i think that the designer recommendation is to stay with low gain since it sounds better and only go high for the most difficult headphones... I believe the HD800's are not so difficult to drive.
A very good little amp in general.
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Deleted
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Post by Deleted on Jan 27, 2012 18:55:40 GMT
The Objective2... headphone amp, by JDS Labs a.k.a. 'NwAvGuy'. JDS labs is not NwAvGuy (my evil twin). JDS labs, just like Epiphany Acoustics (Mike might remember this guy) and others simply sell the 'open source' design in kit or built form. There is nothing much wrong with the design, but then again a lot of amps are designed pretty well. His design is based on the fact that with cheap (non-audiophile) components an amp can be made that cannot be told apart from much more (equally well) designed amps in any blind listening tests. If you feel you can hear differences between the O2 and any other Low Ohmic headphone amplifier that meets minimum requirements you should take up his challenge... could be lucrative... nobody has come forward though.
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Post by dalethorn on Jan 28, 2012 3:02:15 GMT
Thanks solderdude, I hope I got it right this time.
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Deleted
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Post by Deleted on Jan 28, 2012 7:12:02 GMT
yes..
If there is one thing that I would change it would be the power supply part. Especially the charging part. It consists of a simple resistor that constantly applies a charging current (14mA) that is not shut down on a full charge. Since this current is about 1/20th of the capacity (300mA/h) I personally wouldn't leave it on constant mains voltage. NiMH batteries are sensitive to overcharging and 14mA is too much as a trickle current for 9V batteries. Overcharging and thus shortened lifespan of the batteries is a real thing (depending on battery type/brand)
The diodes in series with the 12V and 9V add resistance to the power supply part including the MOSFET's which act as a switch (low Ohmic) not as a regulator. He 'solves' it by adding 220uF caps which indeed lowers the impedance from the power supply but not all. Another thing that aids in his defence is the use of opamps which have a good PSSR, meaning garbage on the powersupply rails is greatly attenuated (70 to 90 dB) so shouldn't affect the output signal much.
The internal resistance is not close to 0 Ohm... Alex wouldn't like that, personally I wouldn't too in certain circumstances. How much of this is audible is appearant from the reviews he gets. No-one complaints yet....
For a portable design (it was intended for portable use) the power supply circuit is good enough as it wouldn't be left on powered externally for weeks. If you are going to use it as desktop amp I would remove the batteries or wait for his ODA design.
Also the gain switch configuration I would have done slightly different as would the PCB design (minor gripes, nothing actually flawed there)
A thing I would have added is DC protection (he does in the ODA) but this complicates the design and draws extra power so from a portable Amp standpoint I understand why he omitted it. Most amps do not have DC protection by the way.
Another thing I would change is something NwAvGuy absolutely hates and because it is his design I won't mention it.
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Post by dalethorn on Jan 28, 2012 7:56:43 GMT
Anything that runs on batteries I run it on batteries. For one thing the sound should be cleaner with no connection to mains. Then when the thing runs down just recharge the batteries. For many things I have I can swap the batteries, which I prefer. This amp will not be convenient for that. I did swap the batteries tonight but it took awhile, unscrewing the screws and removing the guts. I won't do that again any time soon. People leave their laptop computers plugged in all the time, and it kills the batteries eventually. That's where I learned to economize.
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Deleted
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Post by Deleted on Jan 28, 2012 8:02:15 GMT
Wot ! Next to no headphone damping factor ?
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Post by jmwreck on Jan 28, 2012 10:55:52 GMT
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mrarroyo
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Post by mrarroyo on Jan 28, 2012 14:05:47 GMT
That O2 amp is larger that what I expected.
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Deleted
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Post by Deleted on Jan 28, 2012 14:21:34 GMT
People leave their laptop computers plugged in all the time, and it kills the batteries eventually. That's where I learned to economize. These batteries die for another reason. Laptop batteries are (info) Lithium (just like many batteries in phones and DAP's). The problem with Lithium is they age quite fast. Much faster than NiCd and NIMH (including LSD type). The Lithium batteries loose their properties within 2 to 5 years, regardless if they are being used or not. They should be 'stored' with 75% charge if not used. NiCd works longer (but needs to be charged regularly) and should be stored topped off and recharged as soon as it was depleted. NiMH has a shorter lifespan than NiCd but still much longer than Litium. NiMH can be recharged even when only a certain percentage is used. They have higher leakage (especially the higher capacity) and should be charged regularly. LSD batteries hold their charge longer but have lower capacity. I recommend these types especially the 'eneloop' (Sanyo) they hold their charge for many months even upto a year. great for cameras and stuff that isn't used for longer periods and needs to be ready for action when needed without having to recharge before usage. NiMH (and LSD) can be damaged when overcharged. This can happen when the trickle charge is higher than the self discharge. (info) Litium has its own 'record' of what goes in and out (current wise) and can't overcharge.
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Post by billyray on Jan 28, 2012 19:09:58 GMT
I also have an assembled version from JDS labs. Used with Grados (325is), AKG K701, B&W P5 and Shure SE115 (in ears)
I also have a Neco Soundlabs portable and to be honest they do sound pretty similar. However, the O2 seems to be improving with use, so may not yet be hearing it at its best.
Using a phono to 3.5mm lead I have driven it using a Cyrus CD6S player against a GS Solo. The Solo beats it on overall sound, providing a richer more complete sound when provided with a good source. However, when shown an iPod, I think the O2 is my preference.
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xerxes
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Post by xerxes on Jan 28, 2012 21:13:18 GMT
I got a few sets of Sanyo Eneloop batteries and they are much better than standard NiMH batteries, especially for things, like torches and my camera that I only use infrequently. With standard NiMH batteries there would sometimes be no charge left when I came to use them. Also, you can improve the charge storage time of standard NiMH batteries by storing them in the freezer, they self discharge at a slower rate at lower temperatures. They should be kept dry and returned to room temperature before use. I think it works for NiCd as well: www.greenbatteries.com/batterymyths.html#Freezer
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Deleted
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Post by Deleted on Jan 29, 2012 14:47:42 GMT
Owwwww... I can't wait for people to start posting on NwAvGuy's blog that the sonic aspects of his amp can be easily improved by changing opamps, power supplies or components (caps, resistors). That will be the day.... he designed it sub-optimal in that case ;D. I am afraid he either won't 'approve' these post entrries (so won't post it) or makes mincemeat of it. I am sure there will be plenty of this talk on other forums though. Funny thing is FIRST he claimes there are no sonic differences between amps that perform within certain minimal specs (so measurements MAY be different but too small to notice), but after his O2 came out ONLY his design seems to be 'the best' amp and the rest sounds and measures poorly. Some contrary talk can be 'detected'. I do admit on being on the same page as NwAvGuy, for 99% of it though. The Eneloops are GREAT. I have LOTS of other LSD types from Varta, Voltcraft, Ansmann and others but none of them even come close to these Sanyo's. Oh before one wonders... because I am Dutch and drugs policy is notorious in our country... LSD stands for Low Self Discharge ;D
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Post by dalethorn on Jan 29, 2012 14:56:44 GMT
I was surprised mine sounded as good as it did. Maybe I just got lucky. Who determines the quality control anyway? I never heard of a top quality product that was made by just throwing any old parts together. It seems like, if two different companies manufactured these from their own parts, they would sound different. Is the spec for each part so precise that it will always come out perfect?
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Deleted
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Post by Deleted on Jan 29, 2012 15:05:17 GMT
Acc to NwAvGuy this shouldn't be the case (sounding different). I agree with him on this but can fully understand why many people would disagree. The differences in specs of the parts (even if different manufacturers are used) shouldn't be leading to measurable nor perceivable differences. Yes .. again ... many will disagree.. Personally I haven't seen any evidence other than subjective reports or not too scientifically sound 'AB' comparisons. The quality control will be the same guy who soldered it together and put a set of phones on it to test for workings. I severely doubt each device get's individual test reports. The O2 was meant to be a cheap ($30.-) amount of parts performing well in portable applications. It was never meant to be a serious 'high-end' amp. neither are C'Moys but they are certainly sold as such, even by Grado. The O2 can be viewed as a technically better implemetation of a C'Moy. Don't tell him though... Perhaps his next design (ODA) will have more expensive parts. at least the ODA has protection which is certainly recommended with DC coupled amps that can provide lots of power. It was the main issue I find lacking on the O2.
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funk1969
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Post by funk1969 on Feb 1, 2012 17:02:16 GMT
I will skip this amplifier. The hype surrounding it was interesting though...
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Zombie_X
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Post by Zombie_X on Feb 16, 2012 2:14:07 GMT
You know I said I would take the challenge and he never replied, he just ignores me now. He probably thought no one would ever take him up on it. An another note I am working an building my own units, one with audiophile grade parts, and the other with lower grade ones. We'll see how them compare. The Objective2... headphone amp, by JDS Labs a.k.a. 'NwAvGuy'. JDS labs is not NwAvGuy (my evil twin). JDS labs, just like Epiphany Acoustics (Mike might remember this guy) and others simply sell the 'open source' design in kit or built form. There is nothing much wrong with the design, but then again a lot of amps are designed pretty well. His design is based on the fact that with cheap (non-audiophile) components an amp can be made that cannot be told apart from much more (equally well) designed amps in any blind listening tests. If you feel you can hear differences between the O2 and any other Low Ohmic headphone amplifier that meets minimum requirements you should take up his challenge... could be lucrative... nobody has come forward though.
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Deleted
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Post by Deleted on Feb 16, 2012 6:23:41 GMT
I say ... publically take him up on his challenge in one of the forums he is active in. ABI forum for instance or perhaps via Tyll... wouldn't use Jude's site before you do, however, I suggest you build the 2 versions and use a switch and someone else to operate that switch in the circumstances he 'dictates' or set the conditions you like to do the test. The guy is SWAMPED in e-mails so might be the reason he does not react or he is 'chicking' ;D
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xerxes
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Post by xerxes on Feb 16, 2012 12:42:26 GMT
Just been have a look around NwAvGuy's site, the ODA with optional 24/96 USB DAC sounds interesting. I have no real use for portable amps, if I do want music on the move, I'm happy to use the output direct from my phone or MP3 player and not stress too much about the sound quality.
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Post by pete on Mar 19, 2012 23:57:01 GMT
Owwwww... I can't wait for people to start posting on NwAvGuy's blog that the sonic aspects of his amp can be easily improved by changing opamps, power supplies or components (caps, resistors). That will be the day.... he designed it sub-optimal in that case ;D. I am afraid he either won't 'approve' these post entrries (so won't post it) or makes mincemeat of it. ;D I dont think that will ever happen because the NwAvguy blog is completely sensored by him, thats why there are no negative comments on his blog about his amp. I am sure there must have been plenty of comments from people with problems or disagreements by now, but as you said they wont make it on the blog as he just wont approve them, so for all his "objective" take on the audio world, his blog only shows comments that he wants us all to see He may be an audio engineer & quick to point out that nobody else can do what he does (what? is he telling me Burson & other makes cant do anything good or cant measure anything like he does, LOL), & I bet many people who dont understand what all those charts mean probably just trust what he says, but he is just somebody who has made what is essentially a cmoy amp but with a clever way of hyping it up to make us all believe this is the only amp we will ever need to buy, we can forget about any other amps they are all rubbish, flawed designs or simply not needed, but whats this? I hear he is designing a desktop amp with an uprated PSU, why? didnt he just tell us all that the O2 sounded the same as $1000+ benchmark DAC? in that case an uprated PSU is going to make no difference, pllleeease surely people see right through all this BS.
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Post by pete on Mar 19, 2012 23:58:23 GMT
I will skip this amplifier. The hype surrounding it was interesting though... I think you hit the nail on the head & summed this up perfectly.
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Deleted
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Post by Deleted on Mar 20, 2012 5:01:19 GMT
Pete Are you claiming that all amplifiers that meet certain minimum specifications don't necessarily sound the same ? Regards Alex
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Post by dalethorn on Mar 20, 2012 5:26:53 GMT
The O2 amp I bought assembled from JDS Labs was a pretty good deal for $140 USD, and sounded great with the Sennheiser HD800. That said though, removing critical posts for such a low-priced amp is bad. I think in a case like this where the posts aren't offensive, just critical, he should put those into a hidden page and provide a link for hifi sites like this. That way he can keep his hype page "clean" and still do a reasonable service for sites like this. Personally I don't care what anyone says if they're being critical nitpicking the sound like some of the zoo postings I see elsewhere. What I do have a problem with is removing posts that point out specific faults that people need to be aware of.
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Deleted
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Post by Deleted on Mar 20, 2012 6:09:58 GMT
But it doesn't have any faults... it's PERFECT ! so doesn't have to remove posts. He just doesn't have to approve them for showing up in his blog. This is one of the few things that bother me. Funny thing to me is: On his blog (and the other place) he used to burn down a lot of equipment for being below par. Everything with a higher output resistance for instance is bad per definition. I do concur with most of his findings and theories though. Suddenly he is 'challenged' to design something himself. He did and immediatly it's the best thing out there. in fact it is a portable 2 stage Grado RA1 (C'Moy) with a rather good solution to avoid a virtual ground. Of course every brand out there does the same really. Stating their products are better ... that is. Most don't even have a blog or forum and only post positive testimonials. ;D
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Deleted
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Post by Deleted on Mar 20, 2012 6:17:52 GMT
What we need here, is for Frans C.H.Amp and this one to do the rounds of a few RG reviewers. I know which one I would have my money on as being the best value packed and AT LEAST the same performance ! Alex
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