Rev5 seed producing ~13dB higher noise floor

Has anyone noticed a significant increase in noise floor in rev5 daisy seed compared to rev4? I measured around ~13dB higher peak and ~7dB higher RMS.

The flashed program is just writing the output buffer to 0.

It doesn’t sound like a lot but the difference is very noticeable when amplified (with a guitar amp). I know there is a change in the audio codec in rev5, but the noise floor chart in the data sheet is not updated.

Is it this problem specific to the unit I have or is it a universal problem? Has anyone found a way to reduce the noise floor problem in rev5?

1 Like

To address your question, I feel some Daisy-History is necessary, but the short-version is that the difference in noise floor is related to the codec installed on the board.

The original release of Daisy Seed (rev4) had the AK4556 codec installed. The AKM factory that manufactured that codec burned down due to a fire in 2020. Unfortunately, the end result was the part being discontinued, with no plans of continuing to manufacture it.

In order to keep Daisy alive despite this, and to be able to continue manufacturing Daisy Seeds throughout the chip-shortage, we redesigned the board to be hardware compatible with the existing Daisy, but with a more readily available codec. This is the WM8731 that is installed on the Rev5 Daisy Seed.

During this period, there weren’t many components that would fit all of the requirements (voltage, size, availability, compatibility, etc.) required for the Daisy Seed. The WM8731 checked those boxes, and we had actually done a revision of the Daisy Seed with this codec prior to the kickstarter.

The relevant specs that differ with respect to the output noise floor are the SNR (signal to noise ratio). The WM8731 has a specified range of 95dB to 100dB, while the AK4556 has a specified range of 98dB to 106dB. So at a minimum there may be a 3dB difference in SNR performance, but at its maximum there can be up to 11dB (spec’d) difference. In practice, there are other factors that have an effect on the noise (for better and worse) of these ICs; things like the actual devices’ sensitivity to external noise, etc.

We are aware of some of its deficiencies, especially when boosting guitar level signals to the ranges needed. The last of the original “Petal” breakout boards shipped with the last of the Rev4 Seeds, and we decided to discontinue it at that point because we felt it didn’t live up to the quality we like to ensure. We are currently working on a few newer pieces of hardware designed specifically for effects pedal development. At least one of these should be available in the next few months.

As would seem to become an ongoing theme, the WM8731 has also been marked end-of-life, and is now an obsolete part. So we are currently working on a revised version of the Daisy Seed that has another different codec: the PCM3060.

If you’ve used the PatchSM, or have had the Seed2 DFM (another upcoming release) on your radar, you will already be familiar with this codec. Spec-for-spec, it is a lot better than the WM8731, and the AK4556 in the configuration that is used in the redesign (e.g single-ended outputs vs. differential on the other dev boards).

8 Likes

Thanks for giving us the short version and the details - it’s very useful to have that all in one place!

2 Likes

This is very helpful to understand. I’m pretty sure this is the background “noise” I’m hearing on my seed based guitar pedal designs. Good to know it’s not something specific I’m doing on the PCB. Also, happy to hear that a future iteration of the seed will likely solve this issue too! Thank you for this post!

2 Likes

Hi,

I just encountered the same issue, a Rev4 Daisy died for an unknown reason, and I replaced it with a Rev5 in a guitar pedal build similar to the Petal and Terrarium designs. The noise floor on the guitar input is now completely unacceptable.

Do you have any news regarding a release date for a new Seed with a better codec and/or a specific hardware ? (even though, as many others I have designed and manufactured my PCBs around the Seed design)

I just ordered 6 extra Daisy Seeds from Modular Square to build a batch of pedals prior to discovering this issue, if it’s the Rev5 I’ll simply have to cancel the order / send them back…

Hello!

The Daisy Seed will still be available in the future so you do not have to redesign your PCBs. That said, I currently don’t have an estimated date as to when the switch to the PCM3060 codec will happen.

And I recommend contacting Modular Square to check if they’re Rev5.

We’ll keep you all posted with the switch. Thank you for your understanding and the wait.

Thanks for your answer Takumi,

I’ll stay on alert for the next generation of Seeds then, I can still prototype my guitar effects with the Rev5s as long as I know that a fix is coming somewhere down the line, and it might be a good excuse for me to start using the Daisy for Eurorack (which I imagine is much less sensitive to these kind of issues).

Modular Square indeed had Rev5 boards, but I can return them so that’s not too much of an issue.

Thanks!

Hi made extensive tests last winter to get to the bottom of this…

And i also found the Seed 2 which was included in the Q-Bit modules way less noisy than the Rev 5 we could buy at that time…
Here a few graphs, i also have audio recordings of like 10 modules that all show the same pattern.
All recording made with UAD Apollo hardware at the line inputs without any effects

Aurora - very clean, the best of the test

Nautilus - still much cleaner than the Patch

Nautilus

Patch - Worst, especially with the OLED running

cardME - this is our module, based on Petal but with significant efforts to reduce noise
4 layer boards, thick hand routing, shielding , sections in the PCB for each module
It took 11 tries to get there.

cardME

And the best one…48 db gain on the Seed 2 module compared to Patch running Rev 5

All of these are with the Seed running a 2 in 2 out programm, once it is in boot mode it dropped to 95 db.
Yes, I am VERY much looking forward to the new codec.

1 Like

Following up on this codec topic:
Is there a spreadsheet, document or web page with a matrix showing which hardware product and revision uses which codec? I think these are the 3 used:
AKM: AK4556 EOL
Wolfson/Cirrus: WM8731 EOL
TI/Burr Brown: PCM3060 active

Here is what I have, please correct any errors.

Product / Codec

Seed V4 / AKM4556
Seed V5 / WM8731
Seed 2 DFM / PCM3060
Patch SM V4 / WM8731 or PCM3060 ?
Patch.Init() / Uses Patch SM codec
Patch / Uses Seed codec + external codec WM8731 or PCM3060 ? (quad audio)

Thanks for reading,
Mike
(first post)

Welcome Mike -
The libDaisy source code shows which codecs are used for each board.

@tele_player Thanks - I did some review and came up with this:

Product / Codec
Seed V4 / AKM4556
Seed V5 / WM8731
Seed 2 DFM / PCM3060
Patch SM V4 / PCM3060
Patch.Init() / Patch SM codec (PCM3060)
Patch / Seed codec + external codec AK4556 << quad audio >>

-Mike

2 Likes