dalethorn

Well, I'm having the Lehmann audio BCL amp with me now, i switched with a buddy my LDmk4SE, the DT48A seems to benefit somewhat, sound is fuller but rounder, details are abundant, black is black background. It is very good with the HD650, doesn't make that can fast or thin, but smooth. Sounds better on this amp than the Burson. Still nothing beats my Sansui Vintage receiver amp, which i bet can even drive the Hifiman HE6.

I remember the guy at headfonics who had the Shure 940 said the Lehmann did magic for the Shure, so I bet it also does magic for the DT-48A.

I should partially retract what I said about the O2 and the DT-48A - the amp doesn't make the sound too thin - it just seems that way when comparing to other headphones. The Shure definitely does not benefit from the O2 though. I still think the O2 is a great solid state amp, and based on some new tracks with amazing dynamics, the headphone will probably be the limiting factor. If you want a really super stress test for high frequencies, try The Girl From Guatemala by David Chesky (FLAC format) from HDTracks. I have some other great test tracks, but none that have the high freq. dynamics of this track. One listen and you'll see.

So what does the O2 do to the DT48A? Isn't the signature neutral on the O2? Is it just cold and lifeless? If it's that then it should be great for the A.imo unless the O2 is flawed.

Signature stays basically the same. Definitely not cold and lifeless. But the liquid-type sound I hear with my desktop computer and to a lesser extent the iPod, becomes slightly drier and thinner with the O2. The DT-48A just does not need that sort of control that works so well with the Senn 800 and the GMP 8.35D. I read the sensational short review of the Shure 940 by Amclaussen on headfonics, based on him using a Lehmann amp. I did not get a good result with the 940 on the O2. So maybe next I'll get one of those low-cost tube amps for around $250 and then I can use it with the DT-48A and the new Shure 1840.

listening to my o2 again

it seems to be a very analytical amp

thinking of ways to reduce the highs as it gets irritating after awhile

Here's my take on that from worst to best:

Shure 940: Too analytical, needs a tube amp probably.

Beyer DT-48A: Same as 940.

Grado PS-500: Not as bad as the previous two, but not perfect. Good with most tracks.

German Maestro 8.35D: Very good, since the bass balances the highs well.

Sennheiser 800: Awesome, a spectacular sound, a perfect match for the O2.

My best test track for highs (and it has scorching hot highs) is Girl From Guatemala by David Chesky, a FLAC track from HDTracks dot com. With the HD-800 the extreme triangles, xylophone, and other high-freq. percussions are delineated perfectly, with glorious tonal colors. The other headphones don't match up, but the GMP 8.35 shows what needs to happen - if you use a mid-range priced headphone, pick one with good solid bass and even a little warmth to balance out the highs.

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.

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.

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.

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.

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.

Well somebody has been busy with his Mission Objective2, lol. So when is the group buy?

I added a mini-review in the reviews section. I think this little amp is going to do just what 'NwAvGuy' said it would - compete with amps twice the price. I didn't shake it down yet with the big headphones - the 300 ohm Sennheisers, but I will tonight. This little amp is like a solid aluminum brick - love it. I'll get a better idea of any background noise levels at high gain, when it's really quiet late at night.

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.

y not make an LOD

I should learn to do that. I last saw my soldering iron 20 years ago. I should also get into recabling and get rich.

My O2 assembled arrived in a tiny Parcel Post box - it is so cute it's amazing. Tonight I will compare it to the Cute Beyond I bought last year. Listening now with the German Maestro 8.35D - sounds great, good gain. I need a longer LOD cable good quality that doesn't cost a fortune.

Probably you might want to consider velcro, lol

Mainly I was experimenting with the iPod dock output. Looking forward to getting a DAC someday that pulls the digital signal there. I'm skeptical that it can get the "real" USB output, but they say it can be done. How clean it is is questionable.

could recommend u the es7 but its not circumaural hehe

I love the look of several of the AT's but I've never owned one, even though I lived a long time on the same street where their headquarters is in Ohio. Maybe I'll get lucky one of these days and acquire one of those.

hahaha seems like ur ipod will hang by ur headphone

hehe playing with my O2 now

It was funny trying to handle that iPod hanging on a 2 inch cable.

I got the FiiO LOD cable. It has to be the smallest cable I've ever had. Just for fun I plugged the doc end into my iPod Touch, then I plugged the miniplug into the socket of my Vmoda V80 where the headphone cable detaches, and the sound was just like my headphone amp, except no volume control.

I want a fun headphone with good bass. Most importantly, brilliant mids. good soundstage. And play very well with orchestra music(violins) CLOSED HEADPHONES BTW

Try not to have headphones with a flat eq haha. I dislike them

I only run them using a ipod no amp

Circumaural

Thanks a lot I did consider the bose ae2. i really hope the headphones are comfortable

http://www.hifiheadphones.co.uk/forum/head...eview-dale.html

Check out this review I did last night.

hehehe its killing my pocket

been investing lots of money and time on diy stuff and expanding my gears

I sure understand. I was on Facebook tonight and someone mentioned a Objective2 fully assembled headphone amp for $144 USD, so I bought it. Then I was looking for a quality LOD cable and I had a choice for maybe $60 to $100 USD, or the FIIO right-angle LOD for $15. I ordered the FIIO cable. I hope it works. It's crazy when the cable costs as much as the amp.

Trying to conotrol the urge to try new phones. May end up wanting to buy new ones. So spending more time and resources on getting and listening new CD instead.

That's a really good idea. The music always comes first, so having a good collection, you appreciate new headphones much more.

Post the link here once you're done, too bad about the Nagras, my Nagras sound well extremely good

I added it in the reviews section. Hope you like it.

http://youtu.be/qYiit3YRnRg

I hope this link works - a quick review of my six main headphones. I probably need to revise this at some point to add more details. My plan is to add the Philips L1, Vmoda M100, and Shure 1840 when they become available.

Wow, great line up there, so did you manage the Nagra that was on sale?

No, and I really would have, but then I added up the costs and gave up. New earpads and headband would be a must, then, I would be looking at a recable. In fact, I still need to recable my DT-48A since the current cable is very cheap electrical wire, and very microphonic too. Since these new 'phones haven't arrived yet I'm still enjoying the PS-500 and DT-48A about equally. That reminds me - tonight I have to do the mass headphone video for Youtube.

No time for boredom here - new items on the way for me are Philips L1, Shure 1840, V-Moda M100, and a review sample of a German Maestro headphone.

The only Skullcandy Headphones worthy are the MixMasterMike, lousy headband though, the Aviators are 2nd but have a single tone bass.

The DT48A wins over all, just can't get them in any Headphones Store, Dale you did order your pair didn't you? Headphones stores mostly market consumer grade sub quality headphones, rarely true Audiophile equipment. The DT48A is a precision and professional instrument, the A denotes Audiometric class.

The DT-48A should be a simple thing to buy, just order from any Beyerdynamic source, but also order a set of oval earpads and make sure to get a stereo plug to wire onto the end of the cable. It looks so good with the red and blue earcups and that modern industrial design, that it's not just great for music, it's a collector's item that everyone would be jealous of. It has a lean sound, not a bit of fat on it, and when you play tracks that have real bass, you know right then that it's the real deal.