This is a quick build log of Bottlehead Crack OTL tube amplifier with some pictures and little stories. I bought the Crack (and its Speedball upgrade) after I got my hands on a pair of Massdrop x Sennheiser HD 6XX Headphones. I waited until Black Friday to grab it from their website for 15% off.
- Bottlehead Crack Schematic
- Bottlehead Amps For Sale
- Bottlehead Crack Rosewood Burl
- Audio Asylum
- Bottlehead Crack Speedball
Bottlehead Crack First Impression
Build Impressions
Last weekend was so much fun as I took the time to build the Bottlehead Crack -- two of them! It's been a while since I last did DIY work. The last amp I built was the Exstata electrostatic amp, and I remembered how the whole experience was so exhausting, that I discarded my plans for the Audiosector gainclone project (http://www.audiosector.com/lm3875.shtml) and told myself I will never ever do DIY again.
I don't know if it was a combination of long absence from DIY or the Crack being relatively a fun project that makes me go straight into building the second amp, right after I finished building the first. One of the reason that I loathe building DIY amps is in the casework, and when me and Lieven talked about building these amps, I agreed because I know all the components for the case is supplied and with the holes already cut. The only skill that you need to learn to be able to finish the amplifier is quite simply, soldering, and that's something that I'm already quite comfortable with.
Before the Crack, I've built a tube amp with point to point wiring before and I think it's a lot more fun than soldering components into plain PCBs. Of course the design needs to be simple enough for point to point, otherwise it would be quite a nightmare to build. The problem with point to point, however, is when it comes to joining four or five different wires together as you'd need some serious helping hand tools to hold all the cables together simultaneously. With the Crack this is not needed, as Bottlehead uses terminal strips that serves as meeting point for the cables and components. This simplifies the soldering a great deal as you can mount the cables and components into the terminals first, freeing your hand to do the soldering later. The supplied PDF manual for assembly also comes with step-by-step pictures, so you can always refer to the pictures if anything is unclear.
The first build was just an okay build. I had everything soldered well, but I wanted to do something better for the second build; something that would look more like a Woo Audio amp wiring. So I took my time on the second build, carefully planning the routing of the cables and cutting the hookup cables to exact milimeter lengths to come up with a very clean wiring layout. Well, lucky Lieven, because the second build is going to him. Still I was happy with how the second amp turn out to be much cleaner than the first amp.
There are some sections on the build manual that I thought can be done better, but overall I think I'd give the build manual a solid 9/10. I love the fact that they included a high quality, solid core hookup wire with a high heat resistant (teflon?). The solid core wire makes doing the wiring a lot more simple, and the heat resistant sleeving almost very rarely burns. The top aluminum plate comes with the holes perfectly cut (bravo!), but the aluminum surface is too soft that it's really easy to scratch it (perhaps try harder grade aluminum?). Also the transformer cover comes with some amount of rust, but I suppose that's because it comes unpainted (so you can choose the paint color yourself).
You can pay the Bottlehead guys to build the amp for you for a reasonable price if you don't want to do DIY, but even with the added build fee ($150) and the new price on the kit ($279), I still think that the Crack gives you a solid value for the money (I believe the new price and the build fee would come out to about $430). When we bought our amps, it was still under the old pricing, and since we bought three amps, we get a 10% discount that brought the price of each kit to just a tad under $200. For $200, the sound that I get with the Crack is quite a steal as I'd happily take this amp to go head-to-head with the Woo6.
Sound Impressions
Dark, weighty lows and full mids, good soundstage width, PHENOMENAL depth, clean, grainless, black background. With no music playing, the volume knob at max, and using a Superlux HD661 and Shure 1840 (both relatively sensitive headphones), noise level is almost non-existant, in fact cleaner than many commercial amps. I don't know what else should I ask for. The mids are clear up to the upper and mid bass, though low bass section is not so detailed. Micro details are okay (this is what you get with the more expensive amps), but I'm not so bothered as the background is very black and every instrument is very distinct already. With better capacitors, silver wiring, or even a stepped attenuator, it's gonna be easy to get better technicalities but I won't really bother as I'm enjoying the sound very much as it is. The Speedball upgrade reportedly brings an even lower noise floor, but I can't imagine it being lower than it already is right now. The stock Crack build, with stock tubes and components already have one of the lowest noise, the blackest background I've heard on any amps. My friend Drew who bought the Crack together with me and L also bought the Speedball, so I'd wait until his build is finished then I'll do a comparison between the non-Speedball to the Speedball equipped.
Overall I'm very happy with the sound. For $200, the sound that we get almost feels like we robbed Bottlehead for this amp.
I've tried the amp mostly with dynamic headphones with good result:
Sennheiser HD580/650/800
Superlux HD661/662
Shure SRH1840
Alessandro MS-Pro
I tried it with the orthodynamic Hifiman HE-400 and HE-500 and got distortions with both. Not surprising, OTL designs on which the Crack is based on are usually low at power but gives you beautiful sound. I had no problems with the low impedance dynamics (MS-Pro, Superlux, Shure).
Ordering Woes
Bottlehead Crack Schematic
I don't know if we got unlucky with Bottlehead, but the ordering process was such a nightmare to me and L that we both said this is going to be our last Bottlehead order (obviously, after listening to the amp, I'm taking those words back). It took us roughly 2 months of phone calls and emails, both from me and L, before we can get a shipping confimation. Many emails were unanswered, and it was hard to reach them over the phone as well due to the time zone difference. And even after more than a month, they still haven't been able to track the paypal payment I sent to them (I ended up having to send them a screenshot of my paypal to prove the payment was made on day 1). I don't know what happened there, but I do hope that it would be easier the next time.
The package arrived mostly well, but we had some small dents on the edges wood panels (ugh). I'm still thinking if I should ask them to send me extra panels so I can finish the amp with a pristine case work. I think they also missed shipping the bottlehead badges to us.
Unofficial pictures coming up right after this post.
Bottlehead's Crack OTL page can be found here: http://www.bottlehead.com/store.php?crn=224&rn=442&action=show_detail
Bottlehead Crack First Impression
Build Impressions
Last weekend was so much fun as I took the time to build the Bottlehead Crack -- two of them! It's been a while since I last did DIY work. The last amp I built was the Exstata electrostatic amp, and I remembered how the whole experience was so exhausting, that I discarded my plans for the Audiosector gainclone project (http://www.audiosector.com/lm3875.shtml) and told myself I will never ever do DIY again.
I don't know if it was a combination of long absence from DIY or the Crack being relatively a fun project that makes me go straight into building the second amp, right after I finished building the first. One of the reason that I loathe building DIY amps is in the casework, and when me and Lieven talked about building these amps, I agreed because I know all the components for the case is supplied and with the holes already cut. The only skill that you need to learn to be able to finish the amplifier is quite simply, soldering, and that's something that I'm already quite comfortable with.
Before the Crack, I've built a tube amp with point to point wiring before and I think it's a lot more fun than soldering components into plain PCBs. Of course the design needs to be simple enough for point to point, otherwise it would be quite a nightmare to build. The problem with point to point, however, is when it comes to joining four or five different wires together as you'd need some serious helping hand tools to hold all the cables together simultaneously. With the Crack this is not needed, as Bottlehead uses terminal strips that serves as meeting point for the cables and components. This simplifies the soldering a great deal as you can mount the cables and components into the terminals first, freeing your hand to do the soldering later. The supplied PDF manual for assembly also comes with step-by-step pictures, so you can always refer to the pictures if anything is unclear.
The first build was just an okay build. I had everything soldered well, but I wanted to do something better for the second build; something that would look more like a Woo Audio amp wiring. So I took my time on the second build, carefully planning the routing of the cables and cutting the hookup cables to exact milimeter lengths to come up with a very clean wiring layout. Well, lucky Lieven, because the second build is going to him. Still I was happy with how the second amp turn out to be much cleaner than the first amp.
Bottlehead Amps For Sale
There are some sections on the build manual that I thought can be done better, but overall I think I'd give the build manual a solid 9/10. I love the fact that they included a high quality, solid core hookup wire with a high heat resistant (teflon?). The solid core wire makes doing the wiring a lot more simple, and the heat resistant sleeving almost very rarely burns. The top aluminum plate comes with the holes perfectly cut (bravo!), but the aluminum surface is too soft that it's really easy to scratch it (perhaps try harder grade aluminum?). Also the transformer cover comes with some amount of rust, but I suppose that's because it comes unpainted (so you can choose the paint color yourself).
You can pay the Bottlehead guys to build the amp for you for a reasonable price if you don't want to do DIY, but even with the added build fee ($150) and the new price on the kit ($279), I still think that the Crack gives you a solid value for the money (I believe the new price and the build fee would come out to about $430). When we bought our amps, it was still under the old pricing, and since we bought three amps, we get a 10% discount that brought the price of each kit to just a tad under $200. For $200, the sound that I get with the Crack is quite a steal as I'd happily take this amp to go head-to-head with the Woo6.
Sound Impressions
Bottlehead Crack Rosewood Burl
Dark, weighty lows and full mids, good soundstage width, PHENOMENAL depth, clean, grainless, black background. With no music playing, the volume knob at max, and using a Superlux HD661 and Shure 1840 (both relatively sensitive headphones), noise level is almost non-existant, in fact cleaner than many commercial amps. I don't know what else should I ask for. The mids are clear up to the upper and mid bass, though low bass section is not so detailed. Micro details are okay (this is what you get with the more expensive amps), but I'm not so bothered as the background is very black and every instrument is very distinct already. With better capacitors, silver wiring, or even a stepped attenuator, it's gonna be easy to get better technicalities but I won't really bother as I'm enjoying the sound very much as it is. The Speedball upgrade reportedly brings an even lower noise floor, but I can't imagine it being lower than it already is right now. The stock Crack build, with stock tubes and components already have one of the lowest noise, the blackest background I've heard on any amps. My friend Drew who bought the Crack together with me and L also bought the Speedball, so I'd wait until his build is finished then I'll do a comparison between the non-Speedball to the Speedball equipped.
Overall I'm very happy with the sound. For $200, the sound that we get almost feels like we robbed Bottlehead for this amp.
I've tried the amp mostly with dynamic headphones with good result:
Sennheiser HD580/650/800
Audio Asylum
Superlux HD661/662
Shure SRH1840
Bottlehead Crack Speedball
Alessandro MS-Pro
I tried it with the orthodynamic Hifiman HE-400 and HE-500 and got distortions with both. Not surprising, OTL designs on which the Crack is based on are usually low at power but gives you beautiful sound. I had no problems with the low impedance dynamics (MS-Pro, Superlux, Shure).
Ordering Woes
I don't know if we got unlucky with Bottlehead, but the ordering process was such a nightmare to me and L that we both said this is going to be our last Bottlehead order (obviously, after listening to the amp, I'm taking those words back). It took us roughly 2 months of phone calls and emails, both from me and L, before we can get a shipping confimation. Many emails were unanswered, and it was hard to reach them over the phone as well due to the time zone difference. And even after more than a month, they still haven't been able to track the paypal payment I sent to them (I ended up having to send them a screenshot of my paypal to prove the payment was made on day 1). I don't know what happened there, but I do hope that it would be easier the next time.
The package arrived mostly well, but we had some small dents on the edges wood panels (ugh). I'm still thinking if I should ask them to send me extra panels so I can finish the amp with a pristine case work. I think they also missed shipping the bottlehead badges to us.
Unofficial pictures coming up right after this post.
Bottlehead's Crack OTL page can be found here: http://www.bottlehead.com/store.php?crn=224&rn=442&action=show_detail