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dalethorn

Objective2 headphone amp

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The Objective2 is the 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 good.  I tried it with a German Maestro 8.35D headphone 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 test any headphone and amp well.  I also have a Chesky FLAC track, Wonjung Kim - Girl From Guatemala, which has some major dynamics.  Played that one well.  My bass stress-test tracks are Afro Celt Sound System - Inion Daughter, Donald Fagen - Morph The Cat, and Pink Floyd - Speak To Me.

 

The cleanliness of the sound can really be appreciated in the Girl From Guatemala track when the triangles and the extreme high notes of the xylophone(?) are played - the harmonics seem to go on out to infinity.  So far I haven't tested the high gain with a less efficient headphone like the Senn HD-800, but if there is any interest I can give that a spin.

 

Another 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 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.

 

I would have liked to compare this to my Cute Beyond amp by Firestone Audio, but since I'm using a 2-1/2 inch genuine FiiO right-angle LOD cable with the Objective2, and all I have with the Cute Beyond is an Apple composite audio/video cable, it wouldn't be fair (and I did try anyway and the O2 won that one).  The very high-tech LOD to twin RCA cable I got from Firestone does not work with the newer i-devices - 80 bucks down the drain with that cable.

Edited by dalethorn

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yup i have to agree this amp seem to have no problems with anything

but one weird thing is the highs seem very sharp at times

It does seem to have a tendency to tighten up things, but maybe emphasize at the same time. I noticed that mostly with the bass. I'm going to try to resolve the high frequencies thing today, so I'll be able to run some test tracks with the Senn 800, Shure 940 and Grado PS-500.

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Running tests with the Sennheiser HD-800, I almost forgot how good the HD-800 sounds. A headphone this good shouldn't live in the closet.

 

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 works. 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 decent 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! - 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.

 

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 some 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? Check it out...

 

Scarlatti/Kipnis - Sonata in E - 96k FLAC:

A low-volume track played at high gain and maximum volume, having 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.

 

Edited by dalethorn

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yup i have to agree this amp seem to have no problems with anything

but one weird thing is the highs seem very sharp at times

 

Can it be solve by rolling the opamps? Just purchased a fully assembled O2 from JDS Labs, arriving next week I hope. I'll probably be rolling the opamps.

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not too sure there are some other forums discussing tt

i do have the low power opamps on hand recommended by nwavguy himself

no time to play tho

busy cadding and researching for my sch work

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Running tests with the Sennheiser HD-800, I almost forgot how good the HD-800 sounds. A headphone this good shouldn't live in the closet.

 

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 works. 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 decent 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! - 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.

 

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 some 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? Check it out...

 

Scarlatti/Kipnis - Sonata in E - 96k FLAC:

A low-volume track played at high gain and maximum volume, having 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.

 

So Dale, would it be safe to say that the O2 is capable of driving high impedance HP well? How about the harder to drive low impedance cans? i'm really thinking of getting this as a portable.

 

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So Dale, would it be safe to say that the O2 is capable of driving high impedance HP well? How about the harder to drive low impedance cans? i'm really thinking of getting this as a portable.

I would say that since it drove the HD-800 well on the low gain setting, that other high impedance headphones should work well too. I can't say about the planar cans though - the LCD's and the HiMan models, since the high gain is not that much more than the low gain, maybe 10 db, dunno. Any other low impedance that are conventional headphones should work without a problem, unless it's something I never heard of. I pulled everything out of the closet by now to try with this amp - everything works as expected.

 

Well, almost. It did not exaggerate any sibilants or other high freq. artifacts with any of my headphones, but the sound of the DT-48A lost some of the warmth it had with the iPod or even my desktop running off of the sound card, and as a result it wasn't a good match. Supposedly the output impedance of the O2 is super low, and that may be the problem with the DT-48A.

 

Can it be solve by rolling the opamps? Just purchased a fully assembled O2 from JDS Labs, arriving next week I hope. I'll probably be rolling the opamps.

I'd make sure I could switch them back. Be sure to listen very closely first, then after swapping the opamps. This is a one-of-a-kind amp and it might not behave as you predict.

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I would say that since it drove the HD-800 well on the low gain setting, that other high impedance headphones should work well too. I can't say about the planar cans though - the LCD's and the HiMan models, since the high gain is not that much more than the low gain, maybe 10 db, dunno. Any other low impedance that are conventional headphones should work without a problem, unless it's something I never heard of. I pulled everything out of the closet by now to try with this amp - everything works as expected.

 

Well, almost. It did not exaggerate any sibilants or other high freq. artifacts with any of my headphones, but the sound of the DT-48A lost some of the warmth it had with the iPod or even my desktop running off of the sound card, and as a result it wasn't a good match. Supposedly the output impedance of the O2 is super low, and that may be the problem with the DT-48A.

 

This i suppose, can be a tell tale on the amp, what do you think? I think that is because the amp is neutral.

 

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This i suppose, can be a tell tale on the amp, what do you think? I think that is because the amp is neutral.

The amp does seem to be very neutral with normal headphones of all kinds, but I was not getting a neutral sound from the DT-48A. Even if I excuse whatever the iPod/iPad does with the DT-48 5 ohms, I think the O2 is still over-amping the DT-48A. I'll try some more tomorrow.

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The amp does seem to be very neutral with normal headphones of all kinds, but I was not getting a neutral sound from the DT-48A. Even if I excuse whatever the iPod/iPad does with the DT-48 5 ohms, I think the O2 is still over-amping the DT-48A. I'll try some more tomorrow.

You will probably need the 120 impedance adapter with that O2.

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You will probably need the 120 impedance adapter with that O2.

That 120 ohm adapter is legendary. What does it look like? In the 1970's I bought Beyer's adapter box - a beautiful little box about the size of the O2 amp.

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That 120 ohm adapter is legendary. What does it look like? In the 1970's I bought Beyer's adapter box - a beautiful little box about the size of the O2 amp.

I asked someone to make that with 2 pieces hi-grsde 120 ohms resistors soldered in series of the 1/4 " female adapter and added a 1 foot length of cable terminated with a 1/4 " male. You could make it yourself if you can get the mayeriials and a solder kit. It was done in an electrical store actually, cost me like US$25

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