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…
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.
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.
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
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.
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.
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
I’ve been following this thread for a while now. I was experiencing the higher than expected baseline noise floor with the Rev5 seeds in my daisy seed guitar pedal design when simply doing a passthrough of the audio signal from input to output on the seed without doing any processing. It wasn’t terrible, but it was slightly audible.
I was excited to get my Rev7 Seed 1.2 with the new codec to see how it works. A few interesting things to report:
The good news, with the same setup, I’m pleased to report the background noise is completely gone when simply passing the signal through. Very exciting!
The bad news, if I simply add a second one of my guitar pedals to the signal chain (also rev7 seed doing a simple pass through) there is A LOT of background noise. Worse than when the Rev5 was alone. Stacking multiple pedals with the Rev5 seeds did not produce this same result. In fact, if I have a Rev7 first then a Rev5 the noise is also there, but if I have the Rev5 first and the Rev7 second, it isn’t there. It makes me think something about the new Rev7 seed output is interacting weirdly when another buffered input is behind it.
Anyone having similar issues, or have any ideas why this might be happening? My guitar pedal schematic input / output buffers are the exact same as they were designed for the Daisy Petal schematics if that makes any difference.
I setup the seed on a breadboard as shown in the attached image. The seed is being powered by 9v battery power, DGND and AGND are connected, I’m using a TRS stereo jack with Tip connected to the Audio In 1 pin, Ring connected to Audio In 2 pin, and Sleeve connected to GND. The Stereo TRS jack is connected to the stereo headphone jack on my iPhone. Finally I’ve connected my oscilloscope probe to the GND on the breadboard and to the Audio Out 1 on the seed.
I would have expected the same results with both measuring no signal since the audio is not playing.
Also, if I play audio through the input and connect headphones to the audio outputs on the seed it sounds just fine with out noise.
It really seems like something is behaving different electrically with the Seed Rev7 compared to the Rev5 when a High Z connection (like my oscilloscope or the input buffer on my next guitar pedal) is attached to the outputs, which seems to be causing the noise I’m hearing when stacking pedals with a Rev7 before another pedal.
Some of that is probably down to the codec changes that we were discussing earlier in the thread. Over the Seed generations, some of the passives on the audio IO have also been tweaked a bit here and there. That was mostly done to keep the Seeds as backwards compatible as possible, but there still may be some small differences.
That being said, it’s not recommended, especially when dealing with guitars, to directly connect to the Seed’s audio IO. Appropriate op-amp buffer circuits on the audio IO should help a lot to improve these issues.
Thanks for the response Takumi. Unfortunately, that’s the issue though. In my guitar pedal, I do have the op amps before and after the seed rev7, and that noise becomes audible. Doing the experiment without the seed was to try to figure out if I could rule out the actual guitar pedals being the issue.
Here is an experiment for you all to try. Take 2 of the Daisy Petal hardware (my guitar pedal uses the exact same op amps and signal chain) and put Rev7 seeds in them. If you connect a guitar to 1 and then to an amp, you will hear no noise in the signal. However, if you take 2 Daisy Petals and daisy chain them. So the signal goes from Guitar → Petal 1 → Petal 2 → Amp, my bet is you will get the same noisy signal I’m seeing. If you were to put Rev5 seeds in both of those Petal’s you would not.
It’s also not a ground loop, as I’ve done this powering all devices from batteries and the issue remains.
My current theory (and I’m no EE) is that this new Audio codec in the Rev7 seed is expecting the outputs to be loaded, and when they are loaded even just a little bit, the noise is gone, but the op-amps at the output and then input of the next pedal are actually preventing the outputs of the first seed in Petal 1 from being loaded enough, and that same noise we saw on just the seed by itself persists but is now amplified.
Ok, I took this a step further on the breadboard. With a single Rev7 seed playing a wav file with the audio output hooked up to the left side of this circuit I get no noise at point A and noise at point B (using either an oscilloscope or audio probe at those two locations on the schematic, the wav file audio is audible at both points just extra noisy at B)
The reason I did this on the breadboard is because the left side of the circuit is the same as the output op amp circuit in my guitar pedal (and the Daisy Petal), and the right side of this circuit is the same as the input op-amp buffer circuit of the second guitar pedal. Basically replicating the interface between the two.
The same exact circuit on the breadboard with a Rev5 seed has clear audio at both point A and B.
The Rev7 seed, clearly just doesn’t like this configuration for some reason. Hope this helps provide some insight into the behavior
I think I’m running into the same/similar issue with the Rev7 (though I don’t have buffered audio I/O set up yet, which is a significant variable I know…) Loud noise floor/white noise which goes away when the output of the Daisy passes through a passive DI connected to a low-z input on an audio interface, powered by battery and running the Seed Bypass example. Seems to have only become an issue in my circuits after upgrading from Rev4 to Rev7
I’m also running into this issue. I’m using opamp buffers for inputs and outputs. Switching back to Rev5 has solved my noise floor issue for now, but wondering if we can expect a newer revision to address this? Or some other workaround?
@AsaLPatterson While waiting for an official solution, just an FYI, I was able to work around the noise in my case by placing a transformer on the audio output. My testing was fairly limited (tried with my guitar amp, a Headrush, and the line-in on my interface and the noise was down to acceptable levels for those IMO), but mentioning in case you have any laying around and wanted to give that a go for your use case.
I was able to solve my noise issue by low passing the output of the Seed before it reached my output buffer, per a suggestion from another user. Hope this helps someone else!
I may have spoke too soon! (TLDR: I think the transformer was a red herring. But I did find some other interesting details on the symptom.)
After doing more investigation, there seems to be more variables at play in my situation to be useful to others. What I’m finding is that with my audio interface, the noise only occurs if the input gain connected to the Daisy is above a certain point. If I keep each channel gain right below that point, but then compensate with the master gain of the interface, I can juice the usable signal seemingly indefinitely without running into the noise. I’m not sure how to dig further into the implications of this, but it does seem to me like another case of the noise being dependent on the characteristics of whatever is connected immediately after to the Daisy.
As far as the transformer goes, I originally just grabbed a transformer I had laying around from a friend’s record player, so no part number and I don’t know the ratio. Likely a step down ratio, which probably masked the issue in my case because I had to apply makeup gain on my interface. I later tried with a 1:1 EI19 transformer and it actually made the noise worse! So… nevermind on that angle I think.
I was trying to figure out how important the matching of those 1 Meg-ohm resistors is in the low pass filter op-amp circuit above, and found this page on low pass and high pass filters useful, so adding it to the trail:
And there is a lot of generally interesting info at the main page:
