We use the same DC Power Connectors that are used by countless pedal makers all over the world. There is nothing special about them. They usually require a DC Power Plug with a barrel having Ø 5.1mm external diameter and Ø 2.1mm inner diameter. These connectors have 10mm internal depth, so, of course, they fit well any DC Power Plug with a barrel longer than 10mm. The “BOSS standard” DC plugs have a 10mm short-barrel. We chose to solder these connectors on the main circuit board, recessed behind the 2mm thick enclosure wall. Therefore, a DC Power Plug with a 12mm long barrel is needed for good electrical connection.
Why do we mount the DC Power Connector recessed on the main board?
The Hammond enclosures have tapered walls that are 2mm thick. Since the DC Power Connectors are recessed behind the enclosure walls, that thickness adds up and prevents a 10mm short-barrel to fully enter the DC Power Connector.
We don’t want to use wires throughout our builds to connect the potentiometers, switches, and other big parts to the board. This may allow flexible assembly but it creates a lot of mess inside. Moreover, we want to avoid future failures derived from wire snaps. For this reason alone, we do not want to use a DC Power Connector that can be mounted directly on the enclosure wall and further connected with wires to the board. We wouldn’t even have enough room to fit such connectors in our MINI’s. And they look really ugly with their protuberances outside the enclosure. This may be ignored on large size pedals, but again, not on the MINI’s.
Furthermore, if we would want to make square holes through CNC machining to take the DC Power Connector through the enclosure instead of having them recessed 2mm inside behind the enclosure wall, we would not be able to assemble the pedal altogether. We do like all the parts to stay rigid in a strong and compact assembly. Some of these big parts pierce the enclosure on multiple sides through precisely positioned tight holes and they permit a single direction of movement in the 3D space – from bottom to the top face. There is simply not enough free space inside, in between so many holes, to make a lateral assembly move that would permit a DC Power Connector to pass through the enclosure wall.
On the other hand, we don’t want to drill large holes in front of the DC Power Connectors as others do, just to fit the plug’s plastic jacket through the enclosure wall. Some manufacturers go that way but those large holes exposing the connector inside look ugly and often are large enough to allow dust inside. We chose not to do it, for the following reasons.
Our enclosures come beautifully pre-paint by Hammond with a rough black powder coating and we CNC-machine them after printing the white markings. If we would drill larger holes just to fit the plug’s plastic jacket passing through the enclosure that would also leave the aluminum exposed, risking a shortage. Of course, we cannot re-coat the inside of the holes that we drill. Such holes would be even larger if we would want to fit a larger plastic isolation ring instead. They would look even uglier, especially on the MINI pedals.
The aluminum enclosure is connected to the circuit’s ground and negative power polarity, for electromagnetic shielding purpose. So we drill these small-diameter holes which we fit with a plastic ring to avoid possible shortages since the plugs carry the positive polarity on the outside of the barrel. The isolation rings are tight enough to hug the plug’s barrel and they add to the rigidity of the whole ensemble. We did this on purpose. If you accidentally step on the plug, the internal connector might still be protected by the strength of the enclosure. We think this is a good practical design choice and the smaller holes look better.
Is a 10mm short-barrel DC Power Plug totally not usable?
That is not really the case. The fact is that they might be used quite well, also due to the snug fit of the plastic isolation ring. That may keep a 10mm barrel plug well in place most of the time, also depending on the design of the barrel tip.
However, since a short-barrel plug cannot be fully inserted onto the recessed DC Power Connector due to the thickness of the enclosure, this may sometimes result in a fragile electric contact between the barrel’s outer side and the contact blade inside the connector. Such an insertion may become loose and interrupt the powering of the pedal. Mechanical shocks may also move the short-barrel plug and disconnect the power intermittently.
Hence, a DC Power Plug with a 12mm long barrel is needed for a good electrical connection inside the recessed DC Power Connector.
How do we notify users on the requirement for DC Power Plugs with 12mm long barrel?
In product presentations, manuals, and technical specifications present in product pages, we do advise to power our pedals with center negative DC Power Plugs having Ø 5.1mm external diameter, Ø 2.1mm inner diameter, 12mm long barrel. Manuals also advise users on using only good filtered and regulated power supplies and highlight the need of keeping the DC power voltage within specified limits. Additionally, we have compiled a set of relevant technical information in the CompIQ 101 present in every compressor’s presentation page and as a blog post.
Where to get power leads with DC Power Plugs with a 12mm long barrel?
Some high-quality power sources such as those made by Voodoo Labs or Cioks already come with power leads having longer barrel plugs. There are many replacement options for DC power cables fitted with longer barrel DC Power Plug e.g., Voodoo Labs, Cioks, MXR, EBS, etc. eBay is a rich source for very cheap such leads – just look for the ones with a longer barrel. Tech and music shops near your location may offer such leads or separate plugs as well.
If you don’t want to purchase a new power cable you can trim 2 mm from the plastic jacket of a DC Power Plug with a 10mm short barrel.
Since the DC Power Plug’s isolation jacket is usually made from a rubbery plastic, it is very easy to trim a couple of millimeters out of it to expose a longer barrel. We recommend this simple adjustment which works just fine and it takes less than a minute to do it. This way, the 12mm long barrel passes through the 2mm thick enclosure wall and can be fully inserted into the recessed DC Power Connector.