It depends how you would like to hear them.
like a speaker with good imaging and a cohesive sound.
Thanks a lot!
sounds like some work or extra money. maybe one day then
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Hey TwoEars - sorry for the much delayed reply!
First, just to briefly clarify "OTL" refers to a tube amp without output transformers (or - output transformer-less). SET refers to "single ended triode" tube amps, which means it is using a triode tube type and is not a differential or push-pull amplifier. Most of the commonly discussed OTL headphone amps are SET designs - such as the crack, woo 3, woo 2, dark voices, etc. These amps almost all use a 6as7(g) or 6080 tube, in series with high uf caps, as an alternative to output transformers. It is a pretty clever design where - in order to lower the output impedance enough to run high impedance headphones - the signal is actually pulled off the cathode of the tube, rather than the annode. The 6as7(g)/6080/7236/5998 family is really the only option if you want to accomplish this, so that's what all of the above-referenced amps use. Still, the resulting output impedance is a bit on the high side. When implemented well, OTL's tend to produce a full and pleasing sound (with high impedance phones - low impedance will sound anemic and flabby), but there is also going to be some bloom to the bass and likely roll off in the sub-bass.
The original zana deux was/is also an OTL, but of a different and costlier design with lower ouput impedance (and I would say objectively better sounding - very fast, detailed and dynamic). I greatly enjoyed listening to this amp at CanJam, and a family friend had brought an unblemished vinyl copy of HDS701 (see: http://www.tnt-audio.com/sorgenti/vta_method_e.html ) along that we played on craig's system. It was one of the best sounding setups I heard all day. Of the cheaper OTL's, crack comes the closest to an original zana to my ears, but contrary to what some others have suggested in the crack thread, I do not think even a hotrodded crack truly rivals a zana. The new zana deux se, by contrast, uses output transformers, and I have not heard that.
The mainline is a highly regulated, c4s loaded, single gain stage, SET amp, with output transformers, and a big step up in all respects from the crack to my ears - notwithstanding that crack is a good sounding amp in its own right with hd800's. In short, mainline is more refined and detailed, faster, more dynamic, transients much cleaner, and bass far tighter and with greater impact. Trebles are beautifully extended but never strident, which makes it a perfect match for hd800's to my ears - better than a Zana to me (which, like crack, can occasionally manifest some treble sharpness), but reasonable minds can certainly differ once you're in the realm of these sorts of flagship products. As to the trebles and general sound signature, failed engineer discusses the same thing in his post a dozen or so pages back in reference to the ECP L-2 which is very similar under the hood to the mainline. To the best of my recollection, there was nothing I heard at CanJam that I liked as well with hd800's as the mainline (including the zana, WA5, and the $7k TTVJ 307A). I confess I have not heard the zana se, balancing act, or DNA products. If you'd care to read more of my ramblings about the mainline, I've posted some impressions in post nos. 43 and 48 here: http://www.head-fi.org/t/662240/mainline-new-bottlehead-premium-headphone-amp/30 Loquah has also written an exhaustive comparison of his impressions of the bottlehead mainline, crack and s.e.x. here: http://www.head-fi.org/t/683012/bottlehead-amplifier-discussion-comparison-thread-crack-sex-mainline
Great post! Thanks a lot for the input!
Now I'm tempted to build a mainline! I've heard that it's labor intensive but pretty easy and with good instructions so should be doable. Maybe I'll make it an autumn/winter project.
One (stupid) question about the mainline though - what's up with those tubes on the sides? Is that metal around the tubes? To make them heat up better? Doesn't look very appealing to me, you want to see that tube glow right?
Once again thanks for a great post.
Bought a pair of Sennheiser HD800 yesterday! :) I haven't used them very much but I'm very happy with the sound. Right now I'm running them through my Schiit Vali and a HRT musicstreamer II DAc. I know the chain is not very good but for me this is a journey which just started with the headphones. As of now I think it sounds great though and I'm very happy. I have a bottlehead Crack as well which I just have to get some new tubes for and then I'll use that one!
They had a pair of Audeze LCD 2 in the store as well. At first I was def. set on getting them, tried them on and instantly felt the rubbed against the top of my head. If a few minutes of use would do that then I don't see myself wearing them for hours on end as I've done with my HD650.
As of now I don't find the treble really harsh eiter, I thought I was a treble sensitive guy since I sometimes find the treble at live concerts to hurt my ears a bit but these headphones seems good and I don't feel annoyed at all! :)
Quick update on Vali vs Crack. My point goes to the latter.
Much smoother sound, more liquid and not as harsh sounding (I did not think the Vali was that harsh but compared to this it is). The soundstage is also a lot better on the Crack vs the Vali. Overall thus far the sound is a lot more enjoyable from the Crack.
Maybe I shouldn't have generalized the dismissal of the comparison between the two. But no matter what one uses to drive the HD800, it can never be made to sound thick enough to compare with planars. Given the way the drivers are designed and built, there's just too much difference to make the comparison compete for purchase decision. I buy both. They're not like a comparison or competition between the T1 and HD800.
That's just my personal take on the matter. Planars sound fun. HD800 is reference. Again, just my own interpretation. Peace guys.
Ha.. I've done it many times
Hey! Thanks! :)
For the power-tube I'm using a Sylvana 6AS7G tube and a 12AU7WA for the input. Nothing expensive or fancy!
After a few more hours of playing music they have loosened up considerably, the treble has calmed down more and the phones do get more and more enjoyable to listen to.
I have sn: 26458!