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snwcmpr
03/20/2019 4:17 AM
Eth Yirg Nat Idido Gr1 today.

snwcmpr
03/18/2019 8:15 AM
1 lb roasted lasts a week. I can taste the flavor increase to peak, then drop after. Still very good, but interesting to follow the wave of flavor rise and fall.

snwcmpr
03/11/2019 4:10 PM
Roasted Panama Gesha Esmeralda yesterday. Yummy.

Beebee74
03/11/2019 3:10 PM
I seem to have lost any roasting touch I thought I had. Very frustrated to be wasting time and money. I’m hoping someone can provide some insight on roasting at high altitude. I’m at 4400ft. Thank

aicardo
03/07/2019 8:50 AM
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First crack on Gene Cafe
RA5040
Hi - I'm very new to roasting and like others on this forum I am having great trouble trying to hear first crack. I've looked through the forum but I haven't come across any suggestions that have worked for me (at least not yet).

I have recorded my last roast, attached. The recording is truncated so that it starts at 12mins and ends at just past 14mins. My microphone is a good one (Blue Yeti Pro) and I used Audacity to do the recording so that I could view the track both during and after the roast.

I can hear, I think, a few cracks (0:26, 0:36, 0:47, 1:07, 1:11, 1:21, 2:01, 2:07 from start of file - so 12:26, 12:36 etc., from start of roast). I've tried applying various filters, removing noise etc., but I haven't found anything that really helps.

I would really appreciate it if someone who is used to hearing first crack could listen to the recording to see if you can hear 1st crack clearly or not.

BTW, the coffee is a Colombian Supremo. I ended the roast at 15mins based on color and smell. I was aiming for a medium roast, which I think I've achieved.

But I would really like to be able to detect first crack!!

Thanks

Robert
RA5040 attached the following file:
columbia_supremo_180616_-_truncated.zip [8.28MB / 14 Downloads]
 
RA5040
I've applied a high pass filter at 8KHz and amplified the signal and the cracking is easy to hear. If there was some way of doing this is real-time it would be great!

This article https://asa.scitation.org/doi/10.1121/1.4874355 shows that most of the drum/bean noise is below about 7KHz so even though the loudest 1st crack will be at 800Hz, there seems to be a second peak above 8KHz ... which is also true of 2nd crack, so filtering out the signal below 8KHz should be fairly effective.

Has anyone done this though software (or hardware)?

Robert
RA5040 attached the following file:
 
renatoa
I would shorten the roast.
Imo, all the recipes that originates from 2-3 initial Gene roasters advices are too slow compared to the "perfect" roast as described by Jim Schulman in a post, based on his studies in industrial roasting.
You should achieve 175-200C at minute 4 and 232-245C at minute 8, according to his recipe.
To make this happen easier is recommended to lower the quantity, down to 220 grams, at least for the first tests.
 
CharcoalRoaster
When I roasted on my GC for a number of years I found that utilizing the e-stop method of preheating for at least 9-10 minutes improved my roast times.

As far as hearing FC I had to put my ear pretty much right near the roast chamber and even then it was difficult. I went mostly by sight and smell when roasting on the GC.
 
RA5040
Thanks renatoa ... I'll certainly have a look at Jim Schulman's roast profile. I don't imagine that shortening the roast time would help to hear 1st crack though (unless the quicker roast results in louder 1st cracks?).

CharcoalRoaster ... I take it that the e-stop is emergency stop? So you preheat to what, 200C/390F say, then emergency stop, add the beans and restart the roast at say 175C/350F? Actually this is what I did, more or less (Preheat to 200/390; beans in; 175/350 for 4 mins; then 245/470 to end roast. It still took 15 mins for a Medium roast (I'm lucky to have a spectrophotometer that I normally use for printer and display calibration: so I checked the coffee color using this device and the reading gave me an SCAA "Medium" roast color, based on the Hunter Lab color index: https://hunterlabdotcom.files.wordpress.com/2014/03/14-03-01-03-hcci-and-scaa-coffee-standards.jpg)

I've found some software from Apple that may well do the job for 1st crack (and 2nd too, although I wouldn't want to go that far normally). It's called "AU Lab" and it's available here: https://www.apple.com/ie/itunes/mastered-for-itunes/

It's very powerful: you can stack multiple filters, equalizer etc onto the output, and you can set the microphone as input and headphones as output. Of course it does require a Mac, but there's probably the equivalent for Windows and Linux.

What's also very nice is that it's also possible to record the audio using Audacity ... so useful visually during the roast and for analysis later.

I'll give it a go this afternoon and report back.

Cheers

Robert
 
RA5040
Well I roasted an Ethiopia Yirgachefe with microphone, AU Lab, Audacity .... and failed to detect first crack (might have heard one or two around 13mins). Woe is me!

But the roast does seem pretty good: Medium Roast as per SCAA.

I preheated to 200/390 then dropped the temperature to 175/350 and put in the beans. After 4 mins I put the temperature up to 200/390 (I had intended to put it to 245/470). I realized my mistake at around 8 mins and put the temperature up to 245/470 at that point. 230/445 was reached at about 10:30 mins. I e-stopped the roast at 15:30 mins and cooled the coffee with a colander/fan.

I'll have a look at the Audacity recording ... but it could be that I am placing the microphone in the wrong place (it was about 1ft from the drum, with the drum cover down. Any advice?

Robert
 
JackH
Here is an old post from 2012 with a similar problem hearing cracks on the Gene Cafe:

https://forum.hom...rowstart=0

I am not sure if it was solved but maybe it will give you some ideas.
---Jack

KKTO Roaster.
 
renatoa
I would not drop temperature at all, you already lose a lot of heat by opening the cylinder.
Load as fast as you can, at the maximum temperature beans are allowed to have contact.
Just think that in a commercial roaster the beans are dumped in a 200C hot air mass, inside a heavy metal drum, having such inertia that the temperature stay above 150C some 2-3 minutes until TP without any external additional heat !
Gene loading is a lukewarm bath compared to a sauna the beans can afford, and seems liking...
 
RA5040
JackH wrote:

Here is an old post from 2012 with a similar problem hearing cracks on the Gene Cafe:

https://forum.hom...rowstart=0

I am not sure if it was solved but maybe it will give you some ideas.


Thanks Jack ... I hadn't seen that post so I'll trawl through it ... hopefully some good ideas there :)

Robert
 
RA5040
renatoa wrote:

I would not drop temperature at all, you already lose a lot of heat by opening the cylinder.
Load as fast as you can, at the maximum temperature beans are allowed to have contact.
Just think that in a commercial roaster the beans are dumped in a 200C hot air mass, inside a heavy metal drum, having such inertia that the temperature stay above 150C some 2-3 minutes until TP without any external additional heat !
Gene loading is a lukewarm bath compared to a sauna the beans can afford, and seems liking...


OK ... I'll try that: heat up to 200C, dump the beans in, heat for 4 mins at 200C and then up to 245C.

Cheers,

Robert
 
RA5040
OK, well I'm making some progress :)

I roasted another batch of Colombian Supremo, only 220gms this time. I roasted outside with no chaff collector. The Gene was on a concrete floor.

I was able to clearly hear 1st crack. I let the roast go on to see if I could hear 2nd crack, which, again, I was clearly able to hear (also getting a bit smoky).

I also filtered to headset using AU Lab with a high-pass filter and the cracks were even easier to hear.

The Gene is a whole lot quieter outside on a concrete floor, so the acoustics in my shed are not good for hearing the cracks (I had the roaster on a wooden table and the walls are also wood).

I don't know what effect leaving the chaff collector off has, but I'll put it on for my next roast (in a week or two) and I'll report back here in case it may be helpful to others.

I also took your advice (on preheating and weight) and roasted as follows:
Preheat at 200C and dumped the beans in quickly, leaving temp at 200C
Waited 1 min after 200C reached (at 2:48) then increased temp to 245C
1st crack started at 11:45 (at 240C) and ended fully by 14:40
2nd crack started at around 15:10
Ended the roast 30secs into 2nd crack at 15:40

Using my spectrophotometer, this gave me a Dark to Moderately Dark roast (Full City+ to Vienna).

Cheers

Robert
 
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