What is it?

The Tymkrs Bulkhead 1/8" to 1/4" module is a pre-assembled 1U (Intellijel) / 21HP Eurorack module that improves cable management allowing you to route signals from the front of your synthesizer to the inside of your case, and back again! This works with both TS and TRS jacks.

Tymkrs Bulkhead 1/8" to 1/4" module includes four 1/8" jacks on the front of the module and four 1/4" at the back of the module.

The topmost 1/8" along with the topmost 1/4" form 'channel 1". Similarly, there are 1/8" 1/4" pairs for channels 2, 3, and 4.

What kind of functionality does it have and what are some of its use cases?

Each channel pair is normally lifted from the module's shared ground. If you require a channel to not be ground lifted, there is a solder point for each channel. Solder bridging a channel's ground lift pads connects that channel's shield pins to the shared module ground.

All of the ring pins are lifted, only tip and shield are connected. This is to protect 1/4" balanced inputs from the shorted ring/shield nature of the unbalanced patch cables used for eurorack.

In the most basic use-case, a channel can operate as an isolated passthrough between the 1/8" and 1/4" jack on any channel. Simply plug something in channel 1's 1/8" jack, and something into channel 1's 1/4". Those two devices will now be connected to each other, and to nothing else.

However, to make the module more flexible, we have included a multiple bus. Here is how it works:

• If something is patched to the 1/8" jack of channel 1, but nothing is patched into the 1/4" jack of channel 1: The 1/8" jack is now connected to the passive multiple bus.

• Similarly, if something is patched to the 1/4" of channel 1, but nothing is patched into the 1/8" jack of channel 1: The 1/4" jack is now connected to the passive multiple bus.

One basic use-case could be that you presently do not have anything patched into the back of the module. You could patch a clock source to any of the four front channels (for this example we will assume channel 1). The clock signal would now be available on the other three front jacks. The clock signal would also be available on the back jacks of those three channels. If you were to patch something to the back jack of channel 1, channel one would become an isolated passthrough and the clock would no longer be available on the multiple bus.

Another example use-case could be that you patch the clock source to the back 1/4" jack of channel 4. The clock signal would now be available (via the multiple bus) on the 1/8" jacks for channel's 1, 2, and 3.

But, if you were to patch something to channel 4's 1/8", channel 4 becomes an isolated passthrough. This of course means that the multiple bus is now open to be used in a new way by the other three channels.

In its simplest implementation, this module can help tidy up getting traditionally 1/4" connections safely converted to eurorack patch cables. The bonus adaptive mult'ing functionality could be utilized for all sorts of novel splitting, switching, and bussing tricks keeping the module useful over time as your case changes.

Why did you make it?

We initially created the Tymkrs Eurorack Bulkhead Module which allowed for routing of signals from outside our modular set up to inside for cable control. We heard from multiple people that they'd like an option that patched 1/8" to 1/4" and so we did just that! Tymkrs 4hp Bulkhead 1/8" to 1/4". Then we heard that folks might like a 1U version. So we did that for both the Tymkrs 1U Eurorack Bulkhead Module and for this!

I wanted my synthesizer to look nice and neat, but the midi source and audio output were on the front of the eurorack case and needed to go to behind the synthesizer to the rest of my studio. I got tired of running cables from the front of the synthesizer to the back - around the side. So here we are - cable management!

If you have two or more modules, this could also create a wormhole within your synthesizer and help clean up your live case. By patching the back of one bulkhead to another bulkhead, you could create a hidden patch between two parts of your case.

Contents of the Bulkhead 1/8" to 1/4" Module:

• Assembled 1U Bulkhead 1/8" to 1/4" Eurorack Module

Dimensions

• Face Plate Board (21HP x 1U - Intellijel): 4.1875 x 1.5625 x 0.062in (106.3625 x 39.6875 x 1.6mm)
• Depth: 1.625 in (41.275mm)