Writing a review after isn’t easy, so don’t shoot me if this review turns out short 😉 The Bottlehead Crack amplifiers arrived a little over two months after having ordered them on Bottlehead’s website. We ordered a couple of Cracks right before the price increase was announced (more on that later) so that probably explains the long waiting period. As Mike mentioned before in his Facebook notes, it wasn’t always easy communicating with Bottlehead, with emails getting lost/unanswered but a couple of phone calls and lots of emails later we got our DIY packages in the mail.

Bottlehead did forget to send us the logo badges we paid for and the wood of one of the casings was slightly damaged but we were to excited to complain about that and we decided to build them like that. The DIY Crack is a fairly easy to build amplifier, anyone having experience with soldering and a multimeter can surely build one himself. Bottlehead also includes a very detailed step-by-step manual making it almost impossible to screw up. If you don’t feel like building the amplifier yourself, you can always order a pre-assembled Crack from Bottlehead, at an extra cost of course.

Sennheiser HD6. Editor’s Note: An HD6. Don’t we have one already? One of the reason for this newer review is because I noticed that the Sennheiser HD6.

Anyway since Mike did the build on both our Cracks, I will let him talk more about the building process later. Like with every Bottlehead design all in- and outputs are located on top of the amplifier (even the power cable goes in on top).

That can be unhandy when you don’t have a lot of space or when your interconnects and power cable are rather unflexible. It doesn’t really bother me but I’ve seen a lot of people using L shaped plugs with the Bottlehead designs and other DIY’ers have changed the layout and put the connectors on the back and front. It’s a DIY project so if you have the skills you can do pretty much whatever you want. Some people like the look of the Crack and others hate it.

While I think its looks are basic and very cool, I have to admit that having all the cables on top will probably never make it win a beauty contest. Playbill Template Illustrator Brushes more. Looks do matter when buying an amplifier but in the end the sound it produces is more important, and that’s where the Crack really shines. I’ve only been using my beloved Sennheiser HD650 with the Bottlehead amp. I specifically bought the Crack for this headphone after seeing raving posts about this combination over and over.

Most of my other headphones have low impedance or are orthodynamic headphones and the Crack wasn’t developed with those in mind. I did try it briefly with the Hifiman HE-400 and while that worked, I didn’t really experience any distortion like Mike, it doesn’t really need the Crack and it also doesn’t do anything special to it. (only normal with the HE-400 not really needing any amping). I was very happy to notice the Crack was dead quiet with the stock tubes and with my replacement tubes (it doesn’t hum at all). The volume button, being a bit bulky, is smooth to turn and I never needed to turn it further as 10 o’ clock to get to my preferred listening level, so there is more than enough power left for you to play with. Even without any music playing, turning the volume pot was completely noiseless. I rather quickly replaced the stock Electro Harmonix input tube with one of my RCA clear top tubes.

The stock configuration is good but the RCA tube just gives the amplifier a bit more body and weightier bass. Overall the Crack is a very clean sounding amplifier picking up every detail the music has. Bass is deep, well defined and punchy, the mids are very natural and smooth and the treble is nice and sparkling. It is quite a different sound signature as my other OTL amplifier, the Lafigaro 339 (review coming later). This last one is overall warmer sounding, has even smoother mids, more rumble in the bass (but looser) and has less pronounced treble as the Crack.

Both sound great and if I would describe the 339 as “lush”, the Crack would be “clean”. In other words I could say the Crack is more transparent and colors the music less making it very enjoyable but also very non-fatiguing to listen to. I found myself listening for 6 straight hours to the Senn & Crack combo during work without even taking one break, that’s how hard it is to get off Crack (I just had to make one lame drug joke). Of course it’s easy to modify the sound somehow using different tubes. I tried the very popular Tung-Sol 6AS7G and the rare GEC 6AS7G brown base in combination with the RCA 12AU7 I rolled in earlier but after several listening session I kept going back to the stock Westinghouse branded 6080 Tung-Sol. Only needing one power tube and one input tube, tube rolling is one of the most fun things to do with the Crack, and you can easily tune the sound to your liking.

This basic version of the Crack doesn’t have the speedball upgrade and was available for $219 as a DIY kit. Getting this kind of sound for such a low price is simply amazing and an absolute bargain.

Nowadays the Crack is available for $279 (+27%) but it still is an extremely good deal if you can build it yourself. Bottlehead also offers a pre-built version of the Crack for a supplementary $150, making it $429 without shipping.

Unfortunately for those not having the time or knowledge to build it themselves, the Crack is getting close to the prices of amps like the WooAudio WA3($495) and the LaFigaro 339($550) which have a more professional look and an equal or better sound quality. Something to think about. In conclusion: if you are DIY’er looking for an OTL amp to power your high impedance headphones and prefer sound quality over looks (or just like the looks of the Crack like me), don’t look any further. The under $300 Crack is all you need and it will get you addicted for life. Next Page: Mike’s Impressions. I had said before that I found the K550 to be just a tad analytical sounding. After spending more time with it, I don’t think that is the case anymore.

It might be burn in, but more then likely, I am just getting used to the sound. I had planned on getting a MS2+ to go with it, but I am starting to think that the dacport LX would match the sound of the K550 better (I would love to hear your thoughts on that, yes, this post does relate to the crack, i just believe in a good origin story).

I was going to pair them with the asgard, but it is hard not to notice the way you rave about the crack. You had mentioned somewhere, that there was some noise when the K550 and the crack were paired but it was very minor. That is a bit of a concern to me because on some of my classical (MN orchestra’s Beethoven’s 7th per instance), the dynamic range is INSANE, and is frequently almost whisper quiet. If there is any noise, it will be heard. Do you have any thoughts? Would the crack still work, or would I be better with the asgard (or something)? Man, all these awesome reviews coming in, it is paradise in headfonia.

Chris, Checking for shorts, the easiest way is to inspect visually. If you see metal or solder tin touching, or very close, you can take a multimeter, switch to continuity tester and test if the two points are indeed shorted. Switching polarity of the diodes and caps, this is why after doing a few solder points, I always go back and double check things. On the diodes and caps, I think I re-checked their polarity orientation a million times. 😉 The best way to do the assembly is to do it very slowly. Fast assembly in my experience is very prone to errors, and troubleshooting would take much longer than the time you save.

I find their stuff to be good, but overpriced. You can get something equivalent that doesn’t need to be built, isn’t just a plate that sits on an open box, doesn’t take 2 months to arrive, and quite frankly is better looking for around the same price or less. You aren’t getting a nice headphone jack nor potentiometer and knob. The tube sockets aren’t that great. Slotted hardware is just blah. The placement of the power switch makes me reach past the tubes, hence I burn my arms on the tubes.

The transformer bell end cover isn’t coated with anything and gets hot, so it rusts. The only thing that prevents a person from making this kit themselves is that the power transformer is custom-wound by some manufacturer. I still doubt that with the numbers they’re getting that they cost a lot. Their Speedball is really way over-priced. $125 for a few PCBs, a few transistors, a few resistors, a few LEDs, some heat sinks and mounting kits, and standoffs and screws I could build and sell the same thing with a better PCB design for $50 and still make plenty of profitand not have it take 2 months to arrive. If a friend asked me if they should buy one, I would tell them no, and I would just offer to make them one for much less than they could buy it, including the labor. It wouldn’t be too hard to figure out the power transformer issue.

That Eros looks like a fun little kit. I think i like soldering to pcb's better than p2p. Cleaner, faster, easier. I've read some extreme exchanges at audio asylum in reagrds to circuit boards/ground plane design and proponents of p2p. They even have books on the subject. No doubt, p2p has both a circuit designer and a builder. Vintage Schwinn Stingray Serial Numbers. The builder can make or break the design with poor wiring/routing choices.

Just to give props, Aaron is a great builder. Matter of fact I'd use one of his builds without changing anything. His Reduction/Integration is quiet, and I love me a low noise floor. Now long ago I built a Coronet 2.

One thing common with many builders was a system hum, even with impedance to pre amp respected. My ModWright 70dB MC phono stage was quieter than the Hagerman build.

And it was a nice build. I wash my boards after assembly with 99% iso. No flux bridge is going to cause a low level circuit bleed over time. I even used the latest grounding scheme, which was to extend the tranny ground to the star ground. So IMO proper p2p can be as quiet as a well designed circuit board. Time wise, you can build these things pretty quick.

As you know, they have pictures in the manual which speeds the process versus looking and connecting per a schematic. You know what's odd.my phone number is 111-222-3333 and my address is 111 222 Street - zip code is 33333.good luck with that! This was my brothers first attempt and he cut the recess too deep. That's just some white insulating foam strips to raise it up a bit. Since then I've changed the white out to grey and it's not so obvious.

The purpose of this Crack is for me to get some stock voltages and wave forms from for comparison to my current Crack that is fairly well modded. The last modds made some definite improvements and I'm curious as to what the original is. Once I'm done with the testing I'm hoping to build what I want to call a BAC - Big **** Crack with a top plate of 10' x 12' so that there is room to stuff all the mods in without stacking them so close. Current tubes are a Tung Sol 5998 in place of the 6080 and an RCA 5963 in place of the 12AU7. I'll keep the stock tubes in or at least stick with 6080's and 12AU7's for testing. You know what's odd.my phone number is 111-222-3333 and my address is 111 222 Street - zip code is 33333.good luck with that! This was my brothers first attempt and he cut the recess too deep.

That's just some white insulating foam strips to raise it up a bit. Since then I've changed the white out to grey and it's not so obvious. The purpose of this Crack is for me to get some stock voltages and wave forms from for comparison to my current Crack that is fairly well modded. The last modds made some definite improvements and I'm curious as to what the original is.

Once I'm done with the testing I'm hoping to build what I want to call a BAC - Big **** Crack with a top plate of 10' x 12' so that there is room to stuff all the mods in without stacking them so close. Current tubes are a Tung Sol 5998 in place of the 6080 and an RCA 5963 in place of the 12AU7.

I'll keep the stock tubes in or at least stick with 6080's and 12AU7's for testing. Gotcha now!!! Your FICO score is going to tank in the next 3 days. At least i'm giving you a heads up unlike most credit card scammers. I'd love to see the pics of your big crack. Also, are those tubes that you found on your own or did you grab the idea from the BH forums? Those guys seem to really like only a few different tubes and are quite specific.

I've never tube rolled so i need a starting point. At this point, my starting point is STOCK! Build stock and use the stock tubes.

Sometimes you'll get an off balance one but until you listen to stock you don't know how much better (or worse) switching tubes around will be. There are a bunch of 12AU7 variants and some very nice 12AU7's. Just make sure you're using 12AU7 variants and don't use those from the other 12a series (12aT's, 12aX's, etc.). I have some favorites but I will never claim to have heard all of them.

Bottlehead has a thread on rolling tubes in the Crack - 79 pages to date. Also recently a review of tubes with graphs here: Metal Base 7236? Those are nice!

Video of a recent Crack build - very well done. Sounds like a real tattoo opportunity there, paisan!;- ) As an amusing aside -- some years ago we took a family trip 'out west' with my wife's college alumna association (she went to one of them snooty women's college out near a certain Massachusetts mountain from which the school took its name). The tour guide was a woman who, it turned out, was a retired school teacher from Reveah or Meffa or one of the other, similarly quaint and charming suburbs of Bahsten. To this day, I cannot see photographs of a certain well known National Park (National Monument) located in Utah without hearing her voice - and accent.

That place, of course, is called Aaaaaches National Monument. Utah even has it on their license plates!

Have I drifted just a wee tad off topic here latterly? Dreadfully sorry and all that, what?