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July 18, 2011

Custom C7 Power Cable

If you're familiar with a standard IEC inlet, it has three separate connectors for hot, neutral and ground and is on nearly all audio equipment worth its salt, with a few exceptions of course. But we just can't be lucky enough that all equipment has an IEC three prong power inlet, can we?

Furutech gold IEC power inlet
Older equipment and certain newer universal disc players, among other things, have a C7 inlet. A C7 inlet does away with the safety ground connector, and is unpolarized, meaning that the hot and neutral is interchangeable as the cord can be aligned either way on the inlet. There are certain C7 connectors that are polarized which have a square end on one side and a circle on the other to ensure the hot and neutral go through the appropriate route.

Polarized C7 power cord
In my case, I'm currently building a Dynaco ST35 kit which combines the circuit ground with the chassis ground. When this is the case, there is a good chance for hum if attaching a preamp and amp on the same breaker if the circuit ground of each is attached to the safety ground of the power cords. Many of the forums I've visited recommend not attaching the chassis ground to the safety ground on the power connector to prevent hum on Dynacos. Please note that safety ground is called safety for a reason, if it's not connected and the circuit shorts to the chassis, it can be very unsafe.

I'm using a Shurter C7 inlet for my ST35, and it would be blasphemous for me to connect an ordinary C7 power cord to my tricked out new Dynaco ;)

Schurter C7 Power Inlet
So, what are the options for aftermarket C7 cables? PS Audio produces the 12 gauge Jewel power cord which is offered in a C7 configuration and runs ~$70-80 on the street, then there is the Audioquest NRG-1 power cord, which has a similar street price and comes in 16 gauge. Both are larger than the typical 18 gauge unshielded C7 power cord that comes with most equipment and are of course much more attractive.

In the interest of DIY, I chose to build my own. There are sparse few choices for a cable-end plug. Furutech offers a very attractive one, but at $45 as of this writing for a C7 plug is a little rich for my blood ;) It's also a little large for my purposes.

Furutech C7 power plug
Luckily, a builder in Japan offers a low cost C7 connector with solder connections that accept anything up to 16 gauge. These are floating around on that auction site if one searches for "C7 solder".

The power cord starts off a little differently than my other power cords. Rather than twist 10 gauge wires together in a spiral, I chose to use 16 gauge wire and braid it in a tri-braid configuration.

A bundle of 16 gauge silver plated copper in Teflon

Tribraided conductors
Then came the Teflon tape insulation, which covers the braided cable twice over.

Initial Teflon wrapping
A shield is then added over the top, which is connected to the source side ground via a soldered bus wire to create a floating shield.

Wrapped with a tinned copper mesh shield
The next step is two additional layers of Teflon are added to the top, over the braided mesh shielding.

Teflon wrapped 16 gauge power cord
Finally, the decorative techflex sleeving is added to the top, in this case both Chrome XC and black PET sleeving was employed to give a low-level shimmer. The low-cost Marinco 5266 is screwed down on one end and the C7 connector is soldered to the other. A piece of heatshrink is used as a strain relief, and in this case, the joint was bent at 90 degrees while the heatshrink was still hot for ample clearance behind the amp.

High quality DIY C7 power cord

Reverse shot detailing Techflex covering

The Fine Print:
The above steps detailing the creation of a power cord are for entertainment purposes only, and not to be performed under any circumstances. Please remember that attempting to use homemade power cords can be dangerous to you and/or your surroundings. The owner of this blog and all associated parties can not / will not be held responsible if you attempt the process posted below and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and DIY power cables can be a fire hazard. Please keep this in mind.

July 7, 2011

Steampunk Art & Design

I wouldn't necessarily call all of my electronics work my own creations; many of the amps and preamps were existing circuits or kits that I may have modified the parts list or made a few minor circuit changes. As enjoyable as it is to build them, it's preferable for me to stick with tried and true circuits created by the experts and not come up with new schematics of my own volition. There tends to be more enjoyment in the final presentation, the color scheme and the chassis work and even the way the inside looks. A number of people have told me that my builds have a Steampunk look to them. I'm familiar with the movement, and I wasn't even aware of the fact that my design choices tend to follow that look, but perhaps was subconsciously making the design decisions with Steampunk as an inspiration.

I suppose my designers manifesto is that I feel that amplifiers with older technology like vacuum tubes should have a vintage look and patina, even if they are being assembled in the 21st century. Vintage has a different look for different people, but I tend to think of copper and polished brass, gold plating, brown and copper hues with a crinkled / hammered texture, wood and metal grating and leather. These seem to be the same facets that find themselves in the psuedo-Victorian era Steampunk movement of design. I'm not sure that future projects will have the telltale brass gears and non-functional pipes that Steampunk gear tends to have, but I may think up other embellishments as time goes on.

I think that the main inspiration for vintage electronics was a company called Moth Audio that produced a number of designs from 1996 to 2007. There are many purveyors of audio gear that make really beautiful work, but in my minds eye, the aesthetics of Moth Audio gear is second to none. Craig Uthus was the head of Moth and at the time, the work was considered to be "retro-styled", the designs were highly distinctive and still highly sought after today. Craig's partner at Moth was Joel Marshall, a Hollywood prop designer, who designed the beautiful chassis you'll see below. 

Moth Audio NiteLite with 15E Radar Tube

Moth Audio Sphinx balanced line-out amp and phono preamp
I almost feel that these amplifiers belong in an exhibit somewhere. Perhaps someone out there could open up an audiophile museum one day, the cable section alone could take up a whole wing ;)

There is at least a few audio builders out there that fully embrace the Steampunk aesthetic; Aevil at Coppersteam Labs put together the best looking S-5 Electronics K-12G I've ever seen. I'd imagine there's more money invested in the copper than the amp itself, it's a real beauty that looks like it came right out of Bioshock.

AEvilMike's K-12G Amplifier 
I also found a lovely "effect-pedal" if you will made by Peter Groenewoud at Hilltree Productions called the Steampunk Doomsday Machine. The top features two 230V DC bulbs that carry the music signal and create the effect. Lots of wood, brass and copper in this Steampunk design. Peter will not share a schematic on this device as the 230V DC going across those lightbulbs is fairly dangerous.

Hilltree Productions Steampunk Doomsday Machine

Also, a new addition after the 2012 Bay Area HeadFi Meet was Frank Cooters amazing looking headphone amplifier. I don't know too many details about this one, but the glorious copper piping and top-plate and nicely figured hardwood really set this apart from other builds. Evidently all the work inside this beast is point-to-point, and Frank has a matching one that powers electrostats. In this photo it looks like someone has an Audeze LCD-2 headphone plugged in.

Frank Cooter's steampunk-styled headphone amp

In conclusion, I'm not sure that my builds are Steampunk. They may look like it to a certain degree, but it's nebulous where the line of vintage and Steampunk merge, intersect and share common facets. What do you think?

Looking for some steampunk-esq audio cables and equipment? Contact your friends at Zynsonix Audio.

July 2, 2011

The AMB Mini³ (Mini Cubed) Portable Headphone Amplifier

The AMB Mini³ is a cute little portable headphone amplifier designed by Ti Kan of AMB Laboratories in 2007. The size of the amplifier when completed is approximately the size of a pack of cigarettes, or perhaps a stack of credit cards ;) 

The AMB Mini3 Schematic

Available from the AMB Laboratories website is the PCB board, a few selected parts, and pre-drilled panels that fit the Hammond 1455C801 or1455C802 enclosure if you'd rather not make them yourself. I'm not a big fan of the unanodized rim around the FPE (Front Panel Express) panels so I'll be drilling them out myself, but if one doesn't have access to a drill press, the pre-made panels would save a lot of effort. 

Because of the size of the board, one has to mount some very miniscule parts, including 1/8 watt resistors and some SMD opamps. SMD stands for Surface Mount Device and means that the device or component is not through-hole, so it is soldered on the side of the PCB that it is mounted on. Most modern components are made by machines using SMDs, but when soldered by hand, care is required. As explained on the Curious Inventor website, solder flux is first placed on the component legs, then solder is added to the tip of the iron, then the solder is carefully added, please view the video here

AMB Mini³ PCB, the size of a credit card
Because of sizing constraints, one really can't drop in boutique resistors, capacitors or other such items, but one can manage a little bit of customization. I chose to replace the 1% metal film resistors with 5% carbon film as carbon films can tend to sound a little more natural. I purchased about 10x the amount of carbon films that I needed and measured them with the multimeter, keeping only the ones that fell within 1% and matching them on both the left and right sides. This is much more obsessive than one needs to be, but I like drawing out projects a little bit longer to get more enjoyment out of them ;) 

My populated AMB Mini³ Board

The Mini³ has a built in battery recharge circuit that runs off a wall adapter. The battery is a very tough fit in the Hammond case. I had to file down the batter contact pins, remove the battery wrapper, sand down the plastic around the battery AND file the top of the inside of the case and it all just barely fits. I chose the 9V CTA 325mAH NiMH rechargeable battery that was recommended, perhaps the latest models are a little larger than before. As you can see below, the fit is quite tight. I also re-snipped some of the soldered leads at the bottom of the PCB to ensure they wouldn't short to the case. 

I wanted to make my Mini³ unique, as there are many out there that have already been built by headphone enthusiasts on HeadWize and HeadFi, so I chose to dremel out a vent area (purely for aesthetics) and have the case powdercoated in a textured antique copper. AMB has a nice set of printouts that you can use to drill the holes in the front and back panels, I simply lined them up, taped them on and used the drill press to make the holes. The vent area was quite a bit more work, requiring four drill holes to be placed in the corners, a cutting disc to cut the area between them, and a metal file to de-burr and even up the cutout. 

Chassis Prep
Once this was complete, I trimmed a small piece of perforated metal and used a permanent adhesive to attach it in place. The grill area is colored with a bright copper powdercoat to provide an accent to the antique copper chassis.

Unit Front without panel on, input, output, LED and potentiometer

Unit back without panel on. LED, power inlet and battery

Completed Mini3 unit with brass hardware and aluminum knob

Antique copper textured powdercoat
One might wonder why I chose to build a solid state amplifier since nearly everything on the Zynsonix blog is tube-based. There are a couple of tube-based portable amplifiers out there. Todd the Vinyl Junkie developed one a few years ago and there's the DIY Oatley Electronics K272A for a mere $27 that people seem to like. I haven't tried either of the two units, but as tubes tend to be fragile and microphonic, I'd be a little concerned about them banging around in my pocket for extended periods of time, even with damper rings. The AMB Mini³ offers a nice warm sound without the tubes, so it is highly recommended in my book. 

The Fine Print:
Please remember that building circuits and performing circuit modifications can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. Please keep this in mind.