I also like the way my HD-600's sound with it. I love the way my 600 ohm Beyer DT 880's sound with this amp. I have a Bottlehead Crack + Speedball.Uses output transformers to work with a wide range of headphones. It’s a different design to the Crack as the S.E.X. The next step in the Bottlehead range is called the Single Ended eXperimenter kit (or S.E.X. After thoroughly enjoying the Crack for over a year, I decided it was time to enjoy the next step up in the Bottlehead range for both a challenge and a new step towards audio nirvana. I don't listen to it much.Some time ago I built the Bottlehead Crack amplifier and reviewed both the build process and the resulting sound.Has a lot more wires than the Crack (partly due to having two output transformers) so it’s a slightly more complex build, but it’s still fairly simple point-to-point wiring with no circuit boards or finicky micro components.The Bottlehead Crack OTL Headphone. In addition, of the three kits I purchased, not one included all the parts (and given that a kit is just a box. Subtotal 464.00.Bottlehead designers appear to be engaged in a contest to see who can cram the most components into the smallest possible space, and hide solder joints behind other components so it’s impossible to get a soldering iron on them.The top of the main power transformer and the brackets on the plate chokes (the things on either side of the transformer) needed thorough sanding to remove the varnish that they are coated with during production. Required a lot of careful preparation. I love the Art Deco period and I thought that style would match the vintage tubeyness of the S.E.X.To achieve the vintage look I decided to paint some of the visible metal parts and my fiancée convinced me to anodise (rather than paint) the aluminium chassis plate – thanks Lisa! PaintingPainting the metal elements of the S.E.X. Was going to take only a tiny bit longer than the Crack… oops! CustomisationHaving built the Crack completely stock in all ways except for staining the wooden base, I decided I would express myself a little more in this amp.
You can see a dark patch on the top left corner of the front piece (the transformer bell) which is some of the left-over varnish that I failed to fully remove.It’s worth adding at this time that masking the plastic parts on the plate chokes is VERY difficult. This image was actually before the first, failed attempt. Having failed once, I stripped all parts bake to 100% bare metal before starting again.In this image you can see the metal parts all sanded and masked for painting. Despite fairly thorough sanding, there were small patches of varnish left on the metal and the varnish reacted with the etch primer to create a crinkled look that would have really messed with the final paint finish. AnodisingI was worried that the anodising was going to be expensive and possibly time consuming. The paint issue was solved by changing paint brands and actually led to a fortuitous change of colour from off-white to cream which better suited my desired colour scheme. I dealt with the dust by lightly sanding the blemished coat and lightly respraying. The only other issues I had were keeping dust out of the fresh paint job and paint quality issues. AssemblySo far everything I’ve discussed I did on my own, but I actually bought the kit with 2 friends (1 kit each) and we agreed to build them together.The first stage of building was a night of assembly where we screwed all of the components to the chassis plate in preparation for a separate wiring and soldering adventure.The assembly stage of the S.E.X. The finished product perfectly matched the sample Jimmy at Riga had showed me and was a perfect match for my design idea. Before you think Riga did a bad job, please read on because their work was wonderful!I don’t fully understand why, but for some reason, the colour on the chassis plate became uniform over the next few days and went more brown than yellow (as I had wanted). I had ordered the bronze colour, but expected something much more brown, much less yellow, and much more consistent in colour. I delivered to them a simple aluminium plate (as seen to the left) and received back a strangely mottled looking brassy coloured plate. I can highly recommend this approach!The first step in the wiring of the S.E.X. This turned out to be a great move because we were able to fold up the cardboard at the end of the night and easily dispose of all the little wire and insulation off-cuts we’d created. It’s not hard as such, but it IS time consuming so please allow plenty of time and some breaks to ensure an enjoyable build process if you decide to buy and make the S.E.X.To do the work, we setup a table with a sheet of thick cardboard to catch any solder drips and prevent damage to the table we were using. We allowed a day and an evening to do the wiring and soldering, but we should have split it over 2 days. Best way to learn excel for macWe all chose 8 ohm wiring because it suits most common bookshelf / desktop speakers and also will work with most headphones, except the most power hungry orthodynamics out there. Lower impedance wiring means a quieter amp, but with less power so it all depends on your usage. You can choose from 4, 8, 16 or 32 ohm loads and should make the decision based on the speakers you will drive with the amp (if you will ever use speakers), or on the power vs noise ratio you are after. At this time we also had to decide on the impedance we were wiring the S.E.X. The biggest challenges in the wiring process are confirming the right parts are used the right ways, especially for the directional components like capacitors and diodes, and also soldering in cramped spaces as the circuit nears completion.In all cases, the instructions are extremely clear and every written instruction is accompanied by a clear picture of the connections being made. For each wire or terminal, there are numbered terminals to connect each end to. You can see the numbers written on the chassis plate in the image to the left and the wiring process is as simple as following Bottlehead’s brilliant and clear instructions. It’s a great idea for those wanting all options, but not necessary in my case.Once the chokes and transformers were all installed we were ready for the hardcore wiring and soldering. Bottlehead Amplifier Manual Never OnceEven though mine’s not bad, if I had my time again there are some things I would do differently to ensure a much neater finished product.Although the measurements in the instruction manual never once left us short of cable, it sometimes seemed to be too much cable. Wire Lengths and PathsBecause the finished product becomes an organised mess of wires and components (see left), it’s important to focus on tidiness as you progress the build. This makes the build slightly more fiddly because stripping and preparing the multi-core shielded wire takes a little more care and time, but it has it’s benefits because the shielding prevents noise creeping into the wire itself takes up less space in a circuit where real estate is in relatively high demand. Uses a mixture of single core and multi-core wire. Hook-Up WireUnlike the Crack, which used single core wires throughout, the S.E.X. With patience, care and attention there’s really nowhere to go wrong. Again I would manually check and plan the path and length for each wire before I cut it.As you can see in the image to the right, the S.E.X. In short, if I were to build the S.E.X.
0 Comments
Leave a Reply. |
AuthorKenneth ArchivesCategories |