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Gene Cafe: Hearing the Cracks
Well, just got my refund on the auto stethoscope I experimented with last week to try to hear cracks better.

When I fist got my Gene Cafe off Ebay it had a large crack in exhaust. Tim Skaling sent me a new one. It turned out to be the new design allowing easy hook-up to flexible dryer vent to go out window. The con is it is harder to hear cracks. In good weather, outside, it is easy to hear cracks because this extra plumbing is not installed.

Talked to someone and they report success with a simple plexiglass baffle that you insert across and in front of open space as the GC roasts. Says it magnifies cracks.
Yesterday I used a cardboard cut-out and made a metal one and a plexiglass one to use outside this weekend or next week.

If anyone has tried this or has other ideas would appreciate more info. Wanted to try John's medical stethoscope idea but was afraid it would melt my neighbors steth rubber.
I have the same model and would be interested in any progress you make with hearing the cracks. You may be interested in the thread "Amplified cracks etc." Seems to be on the same general topic.
You did not tell us the result of putting a cardboard baffle across the front of the roaster space?
Barrie (San Diego, CA)
"So much to learn, so little time."
Hottop 2K+., Artisan, Jura Capresso ENA 3 (i.e. espresso).


gene wrote:

... success with a simple plexiglass baffle that you insert across and in front of open space as the GC roasts. Says it magnifies cracks...

Before finally moving on to a quieter roaster, I used a Gene Cafe with a stethoscope for a few months. For me, having to use a stethoscope to hear the subtle sounds of the roasting process took the enjoyment out of roasting.

However, I find the above suggestion very interesting. It is a similar to an idea that I was considering, but never got around to trying. I had considered modifying/replacing the round removable cover on the side of the large chaff collector. It seems to me that this large side opening might provide an easy location to experiment with the idea of a thin metal resonating baffle to amplify cracks.
Ciel... seeking Heaven in my cup with ................................................................................................................. EXPOBAR Brewtus II - MAZZER Mini E - MAHLK�NIG Vario - GeneCafe - RAF-1 Extreme (Modified B-2 HOTTOP) - BellaTaiwan XJ-101

Had a number of folks suggesting this saying it made a diff to them. I could not tell an ounce of difference.
To me it was common sense that one made of light metal would amplify better than paper. Not so. I tried both after being disappointed with paper.

Just got off the back patio from roasting. I don't mind sending you the metal baffle if you send me your address to gecounts at gmail dot com.

The only time I ever used it was when temp gets in 30's. Sometimes I'll insert it into place to help chamber stay hotter while roasting outside in a packing box.
Have the packing box engineered so exhaust is out top with a cardboard flap to check progress of roast in chamber. I don't need the baffle.
And I asked the following question on another forum re "at what frequency or decibel does a roasting bean crack":

In winter when I drop dryer vent hooked up to my GeneCafe Roaster and routed out utility room window I can't hear cracks. Have tried a stethoscope, baffles fitted to roast chamber to amplify cracks. Nothing works.

Someone mentioned noise canceling headphones but others say they don't work for this application.

If someone knows at what decibel or frequency range the cracks occur one could approach a headphone company.

Would appreciate comments.

So far interesting comments. Allon out in eastern VA had hooked his roaster into Apple app and result was some nice spectragraphs.
There is an answer out there somewhere.
Well decibel (DB) is a unit for comparing the level (amplitude) of a sound, and varies, greatly, depending on how close the mesuring device is located to the source. Frequency is probably the answer you want. I believe another post on this forum puts it near 12KHz..
No oil on my beans...
...I think the simple, inexpensive, approach might be this:
1) Acoustic guitar pick-up/pre-amp/eq = $12.00 (ebay China)
2) Guitar headphone amp = $15.00 (several places)
3) Headphones

Of course if you happen to have a Fishman laying around, use that.

Placing the pick-up would be interesting...hummm..
No oil on my beans...
oldgearhead wrote: " ... I believe another post on this forum puts it near 12KHz ... "

Yes, that was me. In the thread "Amplified cracks etc." I posted a link to a recording I did of a Gene Cafe roast, and the results of some preliminary experimentation where I found that equalizing out all frequencies except a band centred at 12KHz gave a good indication of 1C, both audibly (ie through headphones) and visually (eg through a spectral display such as in the PC/Mac software VLC or the iPhone/iPad app SpectrumView).

Barrie has also played around with this recording and also found 12Khz to be about right, for this particular example (would need to experiment more to see how well it generalizes).

I was hoping to find a Mac/PC program, or iOS app, that would do the filtering in real time with a simple set up. Haven't had any luck yet, probably the computation involved is a bit heavy.

So I think a simple analogue chain along the lines of oldgerhead's suggestion would be suitable. My thought was a cheap mic into an amplifier (T-amp, amp app on an iPhone using a USB mic into the camera adaptor, guitar h/phone amp as suggested, ...), into an equalizer (old ones are pretty cheap at an audio junk shop or ebay), then headphone out for audio. Need to think more about what can be done for visualization.
I know this is a very old thread but I wanted to add a few points for those like myself new to the site. Unless you have better ears than myself you will need some sort of sound amplification in order to hear cracks. But, I will say that a simple cheap stethoscope works just fine. Two issues...if you place the stethoscope close to the drum its safer due to heat issues that can melt the diaphragm of the stethoscope at the exhaust. The problem is you will need to train your ear. There are many sounds from the motor, bean on bean, bean on metal and the chaff collector. I would spend some time listening to the machine run with a stethoscope. Once you know and recognize normal sounds a forth will appear...duller similar to popcorn popping but more subtle. I missed it on my first two batches. Takes awhile to train your ear but its certainly possible to hear them at the drum.

With that said, at the exhaust lowers ambient sound and magnifies the cracks. The problem is heat. Keep the stethoscope close but not in direct line of exhaust is IMO the best way to hear cracks on the Gene. Hope this helps.
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