[ohcrapgorillas]

  Oh, yeah. I keep hearing about how great these sound on the Crack. There must be something to it. 

 
It definitely brings out a lot of energy in the music, the sound is more engaging and vibrant. And of course you get that lovely tube sense of space. I've noticed that it's fairly forgiving too despite being very very resolving, certain albums that I wasn't impressed with via O2>HD650 (i.e. Abattoir Blues by Nick Cave & the Bad Seeds or Wavering Radiant by Isis) are actually spectacular on the Crack>HD600.

 

[moriez]

 

 
My recently added Lyr is also really nice and close to my ears but in comparison I prefer the Crack. Why exactly I can't explain. 

Maybe because it's warmer, smoother?

 
I thought about it and the early conclusion is that it's not to do with warmer or smoother or anything like that. Maybe the tubes I'm using have a lot to do with it so more testing would be required. For lack of being able to put into words myself, the difference in what I'm hearing comes closest to what people refer to as PRaT. Specifically the ''toe tapability factor of the music''. This and this post also align with what I think PRaT is and a good read.

 

[shawtuw]

   
It definitely brings out a lot of energy in the music, the sound is more engaging and vibrant. And of course you get that lovely tube sense of space. I've noticed that it's fairly forgiving too despite being very very resolving, certain albums that I wasn't impressed with via O2>HD650 (i.e. Abattoir Blues by Nick Cave & the Bad Seeds or Wavering Radiant by Isis) are actually spectacular on the Crack>HD600.

 
That poor band Isis. How could they have known what would become of their name? lol.
 
On a more related note, I've got the HD-650 coming and I already own the HD-600. I'm running the O2+ODAC with the HD-600 and I absolutely LOVE the combination. I am also planning to get a hybrid or a full tube amp plus another ODAC, since I need another amp/DAC for my fiancee. She currently uses my AT-M50x's without an amp or DAC, but she really wants to have my HD-600's. So, I decided to get the HD-650's instead of getting another pair of HD-600's. I figure we will like both of the headphones, so we'll just switch off occasionally. I'm interested to see how each headphone pairs with the O2+ODAC and then with a hybrid amp + ODAC, or a tube amp + ODAC. If I get a hybrid it will probably be the Project Ember or Schiit Lyr 2. If I get a full tube amp it would probably be a Bottlehead Crack with Speedball or a Schiit Valhalla 2.

 

[ohcrapgorillas]

That poor band Isis. How could they have known what would become of their name? lol.

On a more related note, I've got the HD-650 coming and I already own the HD-600. I'm running the O2+ODAC with the HD-600 and I absolutely LOVE the combination. I am also planning to get a hybrid or a full tube amp plus another ODAC, since I need another amp/DAC for my fiancee. She currently uses my AT-M50x's without an amp or DAC, but she really wants to have my HD-600's. So, I decided to get the HD-650's instead of getting another pair of HD-600's. I figure we will like both of the headphones, so we'll just switch off occasionally. I'm interested to see how each headphone pairs with the O2+ODAC and then with a hybrid amp + ODAC, or a tube amp + ODAC. If I get a hybrid it will probably be the Project Ember or Schiit Lyr 2. If I get a full tube amp it would probably be a Bottlehead Crack with Speedball or a Schiit Valhalla 2.

All of those are solid choices for amps, but there's no substitute for the Crack. It really is just that good. Rarely does anything live up to its hype like the Crack does. I'm amazed amd wowed every time I turn it on and I've had it for months now. The synergy between it and the HD6x0 is really something else.

Edit: on second thought if you're going for planars or something in the future, I'd go Lyr. But if you're sticking with the Senns (personally my favorites below $1000), I can't recommend the Crack highly enough. Roll a 5998 into the power tube spot and a rca clear top into the preamp tube and the HD650 will sing with such energy and realism to vocals and strings that will make you lol at the suggestion of a veil. And with a genalex gold lion up front, the HD600 becomes rich and vibrant and just wonderful.

 

[shawtuw]

All of those are solid choices for amps, but there's no substitute for the Crack. It really is just that good. Rarely does anything live up to its hype like the Crack does. I'm amazed amd wowed every time I turn it on and I've had it for months now. The synergy between it and the HD6x0 is really something else.

Edit: on second thought if you're going for planars or something in the future, I'd go Lyr. But if you're sticking with the Senns (personally my favorites below $1000), I can't recommend the Crack highly enough. Roll a 5998 into the power tube spot and a rca clear top into the preamp tube and the HD650 will sing with such energy and realism to vocals and strings that will make you lol at the suggestion of a veil. And with a genalex gold lion up front, the HD600 becomes rich and vibrant and just wonderful.

 
I don't plan on buying any other headphones for quite a while after these HD-650's and I don't plan on ever getting rid of the HD-600's either. So, I will always have two headphones which would pair well with the Crack. I also like the idea of building the amp myself, as I enjoy that kind of thing. So, I will definitely give the crack a lot of consideration. Have you tried it with and without the speedball upgrade? Is it pretty good even without that? I would probably build it without the speedball upgrade first and then install that later on down the road. 

 

[ohcrapgorillas]

I don't plan on buying any other headphones for quite a while after these HD-650's and I don't plan on ever getting rid of the HD-600's either. So, I will always have two headphones which would pair well with the Crack. I also like the idea of building the amp myself, as I enjoy that kind of thing. So, I will definitely give the crack a lot of consideration. Have you tried it with and without the speedball upgrade? Is it pretty good even without that? I would probably build it without the speedball upgrade first and then install that later on down the road. 

I did the same, I have the Speedball but had the stock Crack for about a month. The stock Crack is very very good and a lot of fun, slightly bassy (all 6080 tubes are said to be slightly bassy, you can always drop a 6as7g in to flatten things out). Treble was a little soft, like a tssss would become a tshhh, but still very enjoyable. Speedball made the bass tighter, definitely cleared up the highs, and took the overall clarity and imaging to the next level. Then there's tube rolling...

 

[shawtuw]

I did the same, I have the Speedball but had the stock Crack for about a month. The stock Crack is very very good and a lot of fun, slightly bassy (all 6080 tubes are said to be slightly bassy, you can always drop a 6as7g in to flatten things out). Treble was a little soft, like a tssss would become a tshhh, but still very enjoyable. Speedball made the bass tighter, definitely cleared up the highs, and took the overall clarity and imaging to the next level. Then there's tube rolling...

 
Nice, well it sounds like it would be really nice once fully upgraded with good tubes and the process of upgrading sounds fun too. I've never heard an OTL tube amp, so I'm interested to hear the difference between that and SS. I've tried to find recordings of each or programs which simulate a tube amp, but I've never found anything useful. 

 

[DarthFader]

Is there a way to get the Bottlehead Crack pre-built other than buying a used one from someone? 

 

[moriez]

  Is there a way to get the Bottlehead Crack pre-built other than buying a used one from someone? 

 
Quite sure someone does. Your best bet is searching or asking in the Bottlehead forum.

 

[RedBull]

Buying from some trusty head fier i think is not bad idea either?
Some builds really are good looking.

 

[shawtuw]

  Is there a way to get the Bottlehead Crack pre-built other than buying a used one from someone? 

 
I think I'm going to go ahead and order one today or tomorrow. That way I can power my HD-600's or my new HD-650's (Which will arrive in 2 days!) with a quality tube amp plus a DAC of some kind while the other one is powered by the O2+ODAC. I've heard a lot about OTL tube amps with the HD-6x0's, but I've never heard one myself. I really hope it is a really noticeable difference and not extremely subtle or non-existent like some of the cables people get into. Each amp and DAC will be at one of our PC's. We both have desktop computers which I built. Both have similar specs and they sit side by side. If it's as good as people say then I bet my fiancee will want the Crack to be hooked up to her computer, lol. She's actually going to be building it with me. 

 
 
I haven't built a Crack yet, but from what I've seen it should be a reasonably simple device to build. I doubt it will take more than a couple nights to build it. It looks like you'll just need a multimeter, a soldering iron, and some solder. I think you also need to glue together the housing, so maybe you'd need some glue and clamps. I haven't payed much attention to the housing part of the amp. I completely understand if you don't have time to build it or if you're nervous about building it, but as long as you have attention to detail you should be fine. If you know for a fact that you're the kind of person who lacks attention to detail and who doesn't understand a lot of the instruction manuals that come with products which require assembly, then you should probably avoid building it yourself. Otherwise, I think building it offers a nice opportunity to learn more about amplifiers (Especially if you take the time to learn about how the circuit actually works). 
 
If it goes together easily enough I might be willing to build you one. You'd have to wait until I get mine together though. I'd want to be sure that it was done properly and that I wont make any mistakes. I do have a degree in Physics and a degree in Aviation Maintenance Technology (Which includes maintenance of onboard electrical systems), and my fiancee just finished her degree in Biomedical Equipment Technology. She did an internship at a major hospital where she had the chance to work with some serious equipment, including things like X-ray computed tomography machines, aka - "CT" machines. So, both of us have a decent understanding of how electronic devices work and how to test them. ie - we're not just random idiots who would be messing with an electrical device for the first time. Now that I've said that, I've pretty much guaranteed we'll screw it up btw, LOL. 

 

 

[DarthFader]

   
If it goes together easily enough I might be willing to build you one. You'd have to wait until I get mine together though. I'd want to be sure that it was done properly and that I wont make any mistakes. I do have a degree in Physics and a degree in Aviation Maintenance Technology (Which includes maintenance of onboard electrical systems), and my fiancee just finished her degree in Biomedical Equipment Technology. She did an internship at a major hospital where she had the chance to work with some serious equipment, including things like X-ray computed tomography machines, aka - "CT" machines. So, both of us have a decent understanding of how electronic devices work and how to test them. ie - we're not just random idiots who would be messing with an electrical device for the first time. Now that I've said that, I've pretty much guaranteed we'll screw it up btw, LOL. 

 

 
That's a very generous offer! Let me know how the project goes. I like to think I'm pretty detail-oriented but I have no experience with a soldering iron and it makes me nervous to think I could spend a few hundred bucks just to screw it up because I don't know what I'm doing. I like to learn. I like to learn less when my mistakes cost me money.

 

[greggie]

Tyll has a great article and video about building the Crack, with lots of explanation.  He really helps with the techniques needed and also gives a sense of the level of difficulty, or should I say, ease of the process.
 
http://www.innerfidelity.com/content/marvelously-addictive-bottlehead-crack

 

[shawtuw]

I've been ABing the HD-600 and HD-650 since my new HD-650 arrived and I'm coming away extremely impressed with both. All listening has been done with an O2+ODAC. When I get a tube amp and a new DAC I'll definitely update my impressions with that as well. I do want to note that the HD-650 was very dark sounding when it first arrived, with significantly rolled off treble and a very bass-heavy sound. During the AB testing right out of the box with my HD-600's there was no contest, the HD-600 was superior because the HD-650 was coloring the sound too much. This worried me a bit, but I believed that perhaps break-in would help and it did. Break-in has made a MASSIVE difference. The break-in on these was anything but subtle. The darkness was markedly reduced within just an hour or two of initial break-in. Several AB comparisons with the HD-600 throughout this initial break-in confirmed my suspicions that the top end was opening up. I actually do recall that my HD-600's did more or less the same thing when I first got them as well. Now the highs are much nicer and are just a bit rolled off and the sub-bass is more pronounced compared to the HD-600. 
 
My initial impressions are that the HD-650 is also a bit more resolving than the HD-600. At first they were not at all, but as they break in the difference has become noticeable. The HD-650 sounds more refined and resolving overall, even though it is not as neutral in its tonality. Once I have maybe 100 hours on them I'll be more certain about my conclusions, but so far I'm loving the HD-650's. Based on my fiancee's initial AB comparisons, she prefers the HD-650 over the HD-600 due to the fact that for her they place the vocals more forward than the HD-600. I think the vocals seem more forward because the treble is rolled off a bit compared with the HD-600. Since she focuses on vocals when she listens to music, she finds this to be a desirable characteristic. I don't think the HD-600's are bad for vocals though, it's just that their neutrality doesn't place them so forward. Before hearing the HD-650's, she still felt that the HD-600's were insanely good headphones (And they are!).
 
It's important to mention that these headphones have similar "voices" overall. You can tell they are siblings and my belief is that you like the sound of one you will still like the sound of the other. You might PREFER one, but it is unlikely that you'll hear the HD-650 and think it is absolute trash compared to the HD-600 or vice versa. Both are extremely competent and well designed headphones. If you could imagine two people in a choir singing in unison, the HD-600 is just a bit higher pitched and the HD-650 is a bit lower pitched, but they're singing the same song and man is it sweet! 

 
 
I can't really say which one I prefer, but I'm leaning toward the HD-650 right now. It could just be that they're new though. I like to think I'm not as susceptible to that (Just look at my reaction to the HE-400, lol), but with these it's hard to say because they're similar to my HD-600's. I love the neutral tonality of the HD-600, they just sound so incredibly natural. But I also love the refined, smooth, and yet resolving sound of the HD-650. The HD-650 is certainly natural sounding as well though, it just has a slightly more colored sound. I think the HD-650 is perhaps slightly more musical as well, it seems to get my head bobbing and my toe tapping a bit more. My thoughts on this are that it is due to the more defined low end and forward vocals in the music. I would say that for most people it makes sense to just pick one or the other depending upon your preferences. I don't think you can really go wrong with either at current prices. Luckily for me, my fiancee and I both love the design and sound of the HD-600 and HD-650, so we will be keeping both for sure!
 
The next step is to get a nice tube amplifier and DAC. I might actually try the HRT Music Streamer DAC after hearing some good things about it. 

 

[deaconblues]

I used to have a HD600 back in 2005.  I also bought a HD650 shortly afterwards and had both headphones for a while.  I sold both off to try a lot of other headphones, but I missed the Sennheiser sound, so bought an old used HD580.  Its drivers were failing with constant connectivity issues, so I ordered HD650 drivers for it.  The FrankenHD580 has been my most often used headphone for the past several years.
 
Last week, I saw a deal for a brand new HD600 which I simply couldn't resist.  I figured that I was probably gonna end up swapping my HD650 drivers into it, but at least I would have a nice shiny new headphone with a snug fit.  This was was an impulse buy triggered by a good deal, and I was getting ready for some buyers' remorse.  However, I'm very happy that my expectations were wrong.  I totally wasn't expecting the HD600 to impress me this much in it stock configuration, but when I tried it, I was blown away with how much more I liked the HD600 sound over the HD650 this time around. 
 
 I can think of a couple of reasons why it has given me such a different impression than before.  First of all, I have a much better amp than when I last had the HD600.  Back in the day, I was just rocking a Rio Karma and a CMOY.  This time around, I'm using the AMB γ1 DAC with M³ amp and σ11 power supply that I built about 5 years ago.  The HD600 sings so beautifully with my current setup.  The mids and treble sound so much crisper than on the HD650 drivers.  The HD650 drivers' bass, while still a notch more than the HD600, no longer seems that much better.  Now that I have a higher quality amp, the HD600 has a more commanding bass presence while also being tighter than how I remembered it.
 
The other factor which may have shifted my opinion to the HD600's favor is age.  Our ears' treble response gradually decreases as we age, and I am 10 years older than I was last time I directly compared the HD650 to the HD600.  Perhaps a possible slight drop at the high frequency end of my hearing has change my preference to the HD600.  The little bit of extra high end which once seemed unnecessary now balances out the sound for me, while the HD650 drivers actually seem a little muffled in comparison.  It's kind of like putting on a new pair of glasses for a prescription that has slightly changed.
 
It has been 10 years, but the HD600 has once again taken the top spot among my headphones.  Paired with my γ1 and M³, its balanced presentation sounds like perfection to my ears.  This time, I'm sure it will occupy a permanent place on my desk.