Daisy Patch Hardware Mods

Eurorack
1

Hi there!

In another post regarding disabling the input normalization on the audio inputs , user shensly mentioned some simple mods that might be possible to change the hardware configuration of the Patch module itself. I myself have had a hard time chasing down some details on the patch’s PCB revisions and would like some help (such as the normaling resistors mentioned in the above post).

I should note that I do not currently own a Patch module, but I am trying to see if what I want to do is possible based on online resources and will order one as soon as I get more information.

For my application, I am wondering about disabling/shorting around the AC coupling on the AUDIO INPUTS so that I can use them for CV control. I have found a few threads about people trying this for the audio outputs, but not much on the audio inputs themselves. From the schematics, it looks like there isn’t a coupling cap on audio inputs 1 and 2, but there is on inputs 3 and 4. I recognize that this becomes a bit more complicated with the usage of the codec and its specific settings, so I am hoping someone can shed more light on how all of that works together and why the circuit paths look different.

My goal is to to make a sort of chord multi-oscillator with four v/oct CV inputs AND at least 1 extra CV input to change some sort of parameter about the oscillators (waveshape, detune, or something).

So this post has a few purposes: 1) to start a discussion about Patch mods people have tried, 2) to maybe help work out new mods that haven’t been attempted yet, 3) collect some more details on board revision details, and 4) (selfishly) help me figure if its possible to convert (any or all) the audio inputs to DC coupling.

Thanks!

2

First pair of inputs are connected to Daisy seed that has its own caps, while second one to external codec. AC-coupling caps on Seed are tiny and can be challenging to remove.

AK4556 (used on earlier revision of Seed and as Patch’s second codec) has a digital HPF which is enabled via pulled up pin.

3

Thanks for the response! This leads me to a few follow on questions…

  1. Is there any reason that modifying one pair (internal audio vs external audio) would be advantageous over the other, if the difficulty were equal? That is, if the AC caps on the seed were easy to remove, would the results be more or less the same? Does one of the codecs deal with DC better than the other?

I have beginner-intermediate knowledge here, so I am also trying to learn how to figure this sort of thing out in the future.

I ask because buying a new Seed is a lot cheaper than a whole new Patch, so if I were to botch it, there’s less damage done if I mod the Seed. Since the Seed can be replaced, that’s a $40 dollar mistake rather than a $300 one. Alternatively, I may want to keep a modded Seed and a factory Seed around and swap them out whenever I need.

  1. You mention that there are different versions of the Seed PCB around, are there various versions of the Patch too? If so, is there anywhere that has more details on that?

I would also like to remove the normalization, per the other post I mentioned above, but I cant find a full diagram or image of the rev6 board that was mentioned.

Thank you again for the help so far!