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The Sound of Silence (or First Crack...)
cdrake39
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Posted on 11/04/2020 12:17 PM
I attempted to post this yesterday, but was unsuccessful. So I apologize in advance if it gets posted twice somehow!

Anywho, I recently finished my roaster build and discovered that it is pretty difficult to hear FC with the cyclone chaff collector attached. After doing some digging, I see that this is a fairly common issue. Since my hearing isn't the best, I started looking into ways to detect the sound of FC by other means. Based on some previous posts I read in this forum, FC has a sound frequency around 12 kHz. So I download a spectral analyzer on my phone (Spectroid) and taped a mic to the exhaust of my cyclone and recorded the sounds. The screen shots in the image below illustrate my findings.

The first screenshot is my baseline (well before any cracks took place). The second photo is at a BT of 195C and the remaining screenshots with red dots are at BT temps > 200C. I did notice some very subtle changes in the plot (faint pink lines against the purple) that seem to correspond well with FC temps. If there was a way to remove the background noise from the fan, it may make deciphering when FC starts a little simpler. Does anyone know of any apps that are capable of filtering that background noise? Or any suggestions on a better way to go about this? Thanks in advance for your feedback!

Side note - I did come across a program called RoastLearner that tracks the sound of FC using a cheap USB mic and plots it in real time in Artisan. Unfortunately the code/scripts are outdated and I was unable to get it up and running.
cdrake39 attached the following image:
20201103_210604.jpg
 
renatoa
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Posted on 11/04/2020 12:31 PM
https://www.home-...50601.html
 
cdrake39
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Posted on 11/04/2020 12:44 PM

Quote

renatoa wrote:

https://www.home-...50601.html


Thanks renatoa. I saw that link, but couldn't see any conclusion in there regarding the detection of FC using audio cues. There is mention of the RoastLearner program that I referred to in my original post - if I was savvy w/ Python I would try and get that running but unfortunately that isn't the case. I reached out to the developer 'luma' on HRO as he is a member here, hoping he replies back.
 
Anot
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Posted on 11/08/2020 9:30 AM
Interesting idea. I had, unsurprisingly as our systems are very similair, also problem hearing first crack.

As mentioned in my thread I found another solution, basically making my top cap a bit loose so that some air passes out and this makes first crack easy to hear for me. The downside is that some "roasty air" obviously passes into my kitchen, but this is not a concern for me as the majority of the air still passes through the cyclone chaff. Incidentally it makes it easier to smell the roast which can be a powerful tool. I understand this solution cant be used in your case but it got me thinking. As it is evident that just a small opening is enough I think the same effect could be achieved by making a snippet in a rubber gasket for some connection after the roast chamber. The snippet opening could be lined up with the opening of the clamp (where the thread is) and pointed towards where you stand to reduce muffling and direct the sound. I dont think the resulting hole would be big enough to let chaff through, though it will likely get clogged after a while but the occasional poke with a steel wire should clear it up. Not ideal - but maybe worth testing if you have extra gaskets?
 
cdrake39
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Posted on 11/08/2020 8:04 PM

Quote

Anot wrote:

Interesting idea. I had, unsurprisingly as our systems are very similair, also problem hearing first crack.

As mentioned in my thread I found another solution, basically making my top cap a bit loose so that some air passes out and this makes first crack easy to hear for me. The downside is that some "roasty air" obviously passes into my kitchen, but this is not a concern for me as the majority of the air still passes through the cyclone chaff. Incidentally it makes it easier to smell the roast which can be a powerful tool. I understand this solution cant be used in your case but it got me thinking. As it is evident that just a small opening is enough I think the same effect could be achieved by making a snippet in a rubber gasket for some connection after the roast chamber. The snippet opening could be lined up with the opening of the clamp (where the thread is) and pointed towards where you stand to reduce muffling and direct the sound. I dont think the resulting hole would be big enough to let chaff through, though it will likely get clogged after a while but the occasional poke with a steel wire should clear it up. Not ideal - but maybe worth testing if you have extra gaskets?


Hmmm interesting idea! I'll be setting up in the garage soon so even if some chaff gets through it's not a huge deal. Appreciate the feedback.
 
baldheadracing
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Posted on 11/11/2020 8:55 PM
FYI, despite that thread on Home-Barista not being updated for a couple of years, a project is still ongoing. The goal is to develop acoustical tracking tied into Artisan (the software, not the roaster). Sorry, my mind switched off in the Zoom call when it was discussed last month so I don't remember many details. IIRC, the issue currently is microphones. They are collecting data of cell phones recording the sounds to see how that hardware will work.

Myself, I just auto-set FC to be at 392F(200C) and dry end at 300F(149C). Those are the numbers that work on my roaster/BT probes/greens preferences. Doing this seemed weird at first, but I found out that arbitrarily assigning first crack is what some well-known roasters using Lorings do, e.g., Tim Wendelboe. (Loring roasters are incredibly loud; earplugs are needed.) In addition, oOn my roaster I try not to make any adjustments from a minute or so before FC, so the actual sounds of FC don't drive any actions on my part.
 
cdrake39
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Posted on 11/11/2020 10:18 PM

Quote

baldheadracing wrote:

FYI, despite that thread on Home-Barista not being updated for a couple of years, a project is still ongoing. The goal is to develop acoustical tracking tied into Artisan (the software, not the roaster). Sorry, my mind switched off in the Zoom call when it was discussed last month so I don't remember many details. IIRC, the issue currently is microphones. They are collecting data of cell phones recording the sounds to see how that hardware will work.

Myself, I just auto-set FC to be at 392F(200C) and dry end at 300F(149C). Those are the numbers that work on my roaster/BT probes/greens preferences. Doing this seemed weird at first, but I found out that arbitrarily assigning first crack is what some well-known roasters using Lorings do, e.g., Tim Wendelboe. (Loring roasters are incredibly loud; earplugs are needed.) In addition, oOn my roaster I try not to make any adjustments from a minute or so before FC, so the actual sounds of FC don't drive any actions on my part.


Good to hear! Is there a timeline on the implementation of that? Would be very interested to learn more. Also, good to see another Canadian on the forum - hopefully your weather is better than here in Edmonton.

That seems like a good strategy, and something I may have to do until I sort out the acoustics side of things. I did make a notch in the gasket of my RC to let some air escape as suggested by Anot, but I haven't roasted since doing that.
 
renatoa
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Posted on 11/12/2020 2:04 AM
You can detect the FC start even better than acoustically watching the flick near usual FC temperature.
This is how it works for me, the flick start about 15 seconds before any crack, which are very audible on my machines. I give more credit to flick though.
 
cdrake39
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Posted on 11/17/2020 10:58 PM
So I did some more recording on another roast tonight (Guatemalan)
Oddly enough I didn't hear FC until 210C (maybe my BT thermocouple is being influenced too much by the airflow).. But the YouTube video below shows the results. Some clear blips during FC, followed by about 30s of no signature, then more blips that may be the start of SC?

Note: I trimmed a lot of the background noise before FC occurred. In the actual roast it occurred around 9:27 @ 210C

FC START @ 0:37
FC END @ 2:47
SC START? @ 3:20

Edited by cdrake39 on 11/17/2020 11:15 PM
 
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